Patent Application
20140363428
The present invention relates to: a modified FcRn-binding domain having an enhanced affinity for the Fc Receptor neonatal (FcRn) at neutral pH; an antigen-binding molecule comprising said FcRn-binding domain, which has low immunogenicity, high stability and form only a few aggregates; a modified antigen-binding molecule having an increased FcRn-binding activity at neutral or acidic pH without an increased binding activity at neutral pH for a pre-existing anti-drug antibody; use of the antigen-binding molecules for improving antigen-binding molecule-mediated antigen uptake into cells; use of the antigen-binding molecules for reducing the plasma concentration of a specific antigen; use of the modified FcRn-binding domain for increasing the total number of antigens to which a single antigen-binding molecule can bind before its degradation; use of the modified FcRn-binding domain for improving pharmacokinetics of an antigen-binding molecule; methods for decreasing the binding activity for a pre-existing anti-drug antibody; and methods for producing said antigen-binding molecules.
Due to their high stability in plasma and few side effects, an increasing number of antibodies are being used as pharmaceuticals. A conventional antibody targeting a soluble antigen binds the antigen in the plasma of the patient after injection and then stably persists in the form of an antibody-antigen complex until degradation. While a typical antibody has generally a long half-life (1-3 weeks), an antigen has a relatively short half-life of less than one day. An antigen in complex with an antibody therefore has a significantly longer half-life than the antigen alone. Consequently, the antigen concentration tends to increase after the injection of a conventional antibody. Such cases have been reported for antibodies targeting various soluble antigens, such as IL-6 (J Immunotoxicol. 2005, 3, 131-9. (NPL 1)), beta amyloid (MAbs. 2010 September-October; 2(5):576-88 (NPL 2)), MCP-1 (ARTHRITIS & RHEUMATISM 2006, 54, 2387-92 (NPL 3)), hepcidin (AAPS J. 2010, 12(4):646-57. (NPL 4)) and sIL-6 receptor (Blood. 2008 Nov. 15; 112(10):3959-64. (NPL 5)). Reports have described an approximately 10 to 1000-fold increase (depending of the antigen) of total plasma antigen concentration from the baseline upon antibody administration.
As such an increase of the total plasma antigen concentration is not desired, strategies for removing the antigen by a therapeutic antibody have been developed. One of these strategies is to dispose the antigen rapidly using a pH-dependent antigen binding antibody that has increased binding affinity to the neonatal Fc receptor for IgG (FcRn) (see e.g. PCT application no. PCT/JP2011/001888 (PTL 1)). The FcRn is a protein found in the membrane of many cells. An antibody with increased binding activity to FcRn at neutral pH will bind FcRn on the cell surface, whereby the receptor with the antibody is internalized into the cells in a vesicle. As the pH in the interior of the vesicle is gradually decreased, the antigen will dissociate from the pH-dependent antigen binding antibody, owing to its low affinity in acidic pH. The dissociated antigen is then degraded while the FcRn and bound antibody are recycled back to the surface of the cells before degradation. Accordingly, a pH-dependent antigen binding antibody having increased binding activity to FcRn at neutral pH can be used to remove an antigen from plasma and decrease its concentration in plasma.
Previous studies have also demonstrated that Fc-engineering to increase the binding affinity to FcRn at acidic pH can also improve the endosomal recycling efficiency and the pharmacokinetics of the antibody. For example, M252Y/S254T/T256E (YTE) variant (J Biol Chem, 2006, 281:23514-23524. (NPL 6)), M428L/N434S (LS) variant (Nat Biotechnol, 2010 28:157-159. (NPL 7)), T250Q/M428L (J Immunol. 2006, 176(1):346-56. (NPL 8)) and N434H variant (Clinical Pharmacology & Therapeutics (2011) 89(2):283-290. (NPL 9)) showed improvement in half-life relative to native IgG1.
However, such substitutions have also the risk of altering properties of the antibody that are important for the development of a therapeutic antibody such as the antibody's stability, immunogenicity, aggregation behavior and binding affinity for pre-existing antibodies (e.g. rheumatoid factor). It is therefore the main objective of the present invention to provide a modified FcRn-binding domain which not only enhances the clearance of an antibody but also meets the criteria for developing a therapeutic antigen-binding molecule. These developability criteria are in particular high stability, low immunogenicity, low percentage of aggregates, and low binding affinity for pre-existing anti-drug antibodies (ADA).
Prior art documents related to the present invention are shown below. All documents cited in this specification are incorporated herein by reference.
The present invention was conceived in view of the circumstances described above. An objective of the present invention is to provide a modified FcRn-binding domain which has an enhanced affinity for the FcRn at neutral pH; an antigen-binding molecule comprising said FcRn-binding domain, wherein said antigen-binding molecule has low immunogenicity, high stability and forms only few aggregates; a modified antigen-binding molecule having an increased FcRn-binding activity at neutral or acidic pH without an increased binding activity at neutral pH for a pre-existing anti-drug antibody; use of the antigen-binding molecules for improving antigen-binding molecule-mediated antigen uptake into cells; use of the antigen-binding molecule for reducing the plasma concentration of a specific antigen; use of the modified FcRn-binding domain for increasing the total number of antigens to which a single antigen-binding molecule can bind before its degradation; use of the modified FcRn-binding domain for improving pharmacokinetics of an antigen-binding molecule; and methods for producing said antigen-binding molecules.
The present inventors conducted dedicated studies on modified FcRn-binding domains which have an enhanced affinity for FcRn at neutral pH and on antigen-binding molecules comprising said FcRn-binding domain which have low immunogenicity, high stability and form only few aggregates. As a result, the present inventors discovered that substitutions at specific positions of the FcRn-binding domain increases the affinity for the FcRn at neutral pH without substantially increasing the immunogenicity, without substantially decreasing the stability and/or without substantially increasing the ratio of high molecular weight species.
Furthermore, the present inventors conducted dedicated studies on modified FcRn-binding domains with an enhanced affinity for FcRn at neutral pH or acidic pH but without a significantly increased binding activity for a pre-existing anti-drug antibody and on antigen-binding molecules comprising such an FcRn-binding domain. As a result, the present inventors discovered that substitutions at specific positions of the FcRn-binding domain decrease the affinity for a pre-existing anti-drug antibody at neutral pH without substantially decreasing the FcRn-binding activity.
Specifically, the present invention relates to:
[1] An antigen-binding molecule comprising a modified FcRn-binding domain, wherein the modified FcRn-binding domain comprises an amino acid substitution at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436, wherein the numbers indicate the position of the substitution according to the EU numbering.
[2] The antigen-binding molecule according to [1], wherein the FcRn-binding domain has
a) an amino acid substitution of the amino acid at position EU252 and EU434; and
b) an amino acid substitution at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258, EU286, EU387, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436.
[3] The antigen-binding molecule according to [1] or [2], wherein the modified FcRn-binding domain comprises
at position EU238 an aspartic acid,
at position EU250 a valine,
at position EU252 a tyrosine,
at position EU254 a threonine,
at position EU255 a leucine,
at position EU256 a glutamic acid,
at position EU258 an aspartic acid or an isoleucine,
at position EU286 a glutamic acid,
at position EU307 a glutamine,
at position EU308 a proline,
at position EU309 a glutamic acid,
at position EU311 an alanine or a histidine,
at position EU315 an aspartic acid,
at position EU428 an isoleucine,
at position EU433 an alanine, a lysine, a proline, an arginine, or a serine,
at position EU434 a tyrosine, or a tryptophan, and/or
at position EU436 an isoleucine, a leucine, a valine, a threonine, or a phenylalanine.
[4] The antigen-binding molecule according to [2], wherein the FcRn-binding domain comprises an amino acid substitution of an amino acid at one or more position combinations selected from the group consisting of
[5] The antigen-binding molecule according to [4], wherein the FcRn-binding domain comprises:
a) at position EU252 a tyrosine, at position EU315 an aspartic acid, and at position EU434 a tyrosine; or
b) at position EU252 a tyrosine, at position EU434 a tyrosine, and at position EU436 an isoleucine; or
c) at position EU252 a tyrosine, at position EU434 a tyrosine, and at position EU436 a leucine; or
d) at position EU252 a tyrosine, at position EU434 a tyrosine, and at position EU436 a valine; or
e) at position EU252 a tyrosine, at position EU254 a threonine, at position EU434 a tyrosine, and at position EU436 an isoleucine.
[6] The antigen-binding molecule according to [2], wherein the FcRn-binding domain comprises an amino acid substitution at three or more positions, wherein the three or more positions are one of the combinations of the group consisting of
[7] The antigen-binding molecule according to [6], wherein the FcRn-binding domain comprises:
a) at position EU252 a tyrosine, at position EU286 a glutamic acid, at position EU307 a glutamine, at position EU311 an alanine and at position EU434 a tyrosine; or
b) at position EU252 a tyrosine, at position EU254 a threonine, at position EU286 a glutamic acid, at position EU307 a glutamine, at position EU311 an alanine and at position EU434 a tyrosine; or
c) at position EU252 a tyrosine, at position EU307 a glutamine, at position EU311 an alanine, at position EU434 a tyrosine and at position 436 an isoleucine; or
d) at position EU252 a tyrosine, at position EU254 a threonine, at position EU286 a glutamic acid, at position EU307 a glutamine, at position EU311 an alanine, at position EU434 a tyrosine and at position EU436 an isoleucine; or
e) at position EU250 a valine, at position EU252 a tyrosine, at position EU254 a threonine, at position EU308 a proline, at position EU434 a tyrosine and at position EU436 a valine; or
f) at position EU250 a valine, at position EU252 a tyrosine, at position EU307 a glutamine, at position EU311 an alanine, at position EU434 a tyrosine and at position EU436 a valine; or
g) at position EU252 a tyrosine, at position EU307 a glutamine, at position EU311 an alanine, at position EU434 a tyrosine and at position EU436 a valine; or
h) at position EU250 a valine, at position EU252 a tyrosine, at position EU308 a proline, and at position EU434 a tyrosine; or
i) at position EU250 a valine, at position EU252 a tyrosine, at position EU307 a glutamine, at position EU308 a proline, at position EU311 an alanine, and at position EU434 a tyrosine.
[8] The antigen-binding molecule according to [2], wherein the FcRn-binding domain comprises an amino acid substitution at three or more positions wherein the three or more positions are one of the combinations of the group consisting of
[9] The antigen-binding molecule according to [8], wherein the FcRn-binding domain comprises:
a) at position EU252 a tyrosine, at position EU286 a glutamic acid, at position EU307 a glutamine, at position EU311 an alanine, at position EU434 a tyrosine, and at position EU436 a valine; or
b) at position EU250 a valine, at position EU252 a tyrosine, at position EU307 a glutamine, at position EU308 proline, at position EU311 an alanine, at position EU434 a tyrosine, and at position EU436 a valine; or
c) at position EU250 a valine, at position EU252 a tyrosine, at position EU286 a glutamic acid, at position EU307 a glutamine, at position EU308 proline, at position EU311 an alanine, at position EU434 a tyrosine, and at position EU436 a valine; or
d) at position EU250 a valine, at position EU252 a tyrosine, at position EU286 a glutamic acid, at position EU307 a glutamine, at position EU308 proline, at position EU311 an alanine, at position EU434 a tyrosine, and at position EU436 a valine.
[10] The antigen-binding molecule according to [2], wherein the FcRn-binding domain comprises an amino acid substitution at three or more positions wherein the three or more positions are one of the combinations of the group consisting of:
[11] The antigen-binding molecule according to [10], wherein the FcRn-binding domain comprises:
a) at position EU307 a glutamine, at position EU311 a histidine and at position EU434 a tyrosine; or
b) at position EU307 a glutamine, at position EU309 a glutamic acid, at position EU311 an alanine and at position EU434 a tyrosine; or
c) at position EU307 a glutamine, at position EU309 a glutamic acid, at position EU311 an histidine and at position EU434 a tyrosine; or
d) at position EU250 a valine; at position EU252 a tyrosine, at position EU434 a tyrosine and at position EU436 a valine.
[12] The antigen-binding molecule according to any one of [1] to [11], wherein the ratio of high molecular weight species is less than 2%.
[13] The antigen-binding molecule according to any one of [1] to [12], wherein antigen-binding molecule comprises an antigen-binding domain having
a) a lower binding activity for the antigen at pH 5.5-6.5 than at pH 7-8 or
b) a “calcium concentration-dependent binding” activity for the antigen.
[14] The antigen-binding molecule according to any one of [1] to [5], wherein the binding activity of said binding molecule for the FcRn at pH 7 is 50-150 nM, Tm is higher than 63.0 degrees C., and Epibase score is less than 250.
[15]. The antigen-binding molecule according to any one of [1] to [3] and [6] to [7], and wherein the binding activity of said binding molecule for FcRn at pH 7 is 15-50 nM, Tm is higher than 60 degrees C., and Epibase score is less than 500.
[16] The antigen-binding molecule according to any one of [1] to [3] and [8] to [9], and wherein the binding activity of said the binding molecule for FcRn at pH 7 is stronger than 15 nM, Tm is higher than 57.5 degrees C., and Epibase score is less than 500.
[17] The antigen-binding molecule according to any one of [1] to [3], wherein the FcRn-binding domain comprises an amino acid substitution
a) at the positions EU238, EU255 and/or EU258, and
b) at three or more positions, wherein the three or more positions are one of the combinations set forth in Tables 4 to 7.
[18] The antigen-binding molecule according to any one of [1] to [17], wherein
a) at the position EU257 of the FcRn-binding domain the amino acid is not an amino acid selected from the group consisting of alanine, valine, isoleucine, leucine, and threonine, and/or
b) at the position EU252 of the FcRn-binding domain the amino acid is not tryptophan.
[19] The antigen-binding molecule according to any one of [1] to [18], wherein the antigen-binding molecule has a binding activity for a pre-existing anti-drug antibody that is not significantly increased as compared to the binding affinity of a control antibody comprising an intact FcRn-binding domain.
[20] The antigen-binding molecule according to [19], wherein the FcRn binding domain further comprises an amino acid substitution at one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
[21] The antigen-binding molecule according to [20], wherein the FcRn binding domain comprises one or more amino acid substitutions selected from the group consisting of
at position EU387 an arginine,
at position EU422 a glutamic acid, an arginine, or a serine, an aspartic acid, a lysine, a threonine or a glutamine;
at position EU424 a glutamic acid or an arginine, a lysine, or an asparagine;
at position EU426 an aspartic acid, a glutamine, an alanine, or a tyrosine;
at position EU433 an aspartic acid;
at position EU436 a threonine;
at position EU438 a glutamic acid, an arginine, a serine, or a lysine; and
at position EU440 a glutamic acid, aspartic acid or a glutamine.
[22] The antigen-binding molecule according to any one of [1] to [21], wherein the modified FcRn binding domain comprises three or more substitutions, wherein the three or more substitutions are one of the combinations set forth in Tables 12 to 13.
[23] The antigen-binding molecule according to any one of [1] to [22], wherein the modified FcRn-binding domain comprises three or more substitutions, wherein the three or more substitutions are one of the combinations set forth in Tables 14 to 15.
[24] The antigen-binding molecule according to any one of [20] to [23], wherein the FcRn-binding domain comprises:
a) at position EU252 a tyrosine, at position EU387 an arginine, at position EU434 a tyrosine, and at position EU436 a valine; or
b) at position EU252 a tyrosine, at position EU422 a glutamic acid, at position EU434 a tyrosine, and at position EU436 a valine; or
c) at position EU252 a tyrosine, at position EU422 an arginine, at position EU434 a tyrosine, and at position EU436 a valine; or
d) at position EU252 a tyrosine, at position EU422 a serine, at position EU434 a tyrosine, and at position EU436 a valine; or
e) at position EU252 a tyrosine, at position EU424 a glutamic acid, at position EU434 a tyrosine, and at position EU436 a valine; or
f) at position EU252 a tyrosine, at position EU424 an arginine, at position EU434 a tyrosine, and at position EU436 a valine; or
g) at position EU252 a tyrosine, at position EU434 a tyrosine, at position EU436 a valine, and at position EU438 a glutamic acid; or
h) at position EU252 a tyrosine, at position EU434 a tyrosine, at position EU436 a valine, and at position EU438 an arginine; or
i) at position EU252 a tyrosine, at position EU434 a tyrosine, at position EU436 a valine, and at position EU438 a serine; or
j) at position EU252 a tyrosine, at position EU434 a tyrosine, at position EU436 a valine, and at position EU440 a glutamic acid.
[25] The antigen-binding molecule according to any one of [1] to [24], wherein the antigen-binding molecule is an antibody.
[26] Use of the antigen-binding molecule according to any one of [1] to [25] for improving antigen-binding molecule-mediated antigen uptake into cells.
[27] Use of the antigen-binding molecule according to any one of [1] to [25] for reducing the plasma concentration of a specific antigen, wherein the antigen-binding molecule comprises an antigen-binding domain which can bind said antigen.
[28] A method for improving the pharmacokinetics of an antigen-binding molecule, comprising the step of introducing an amino acid substitution into an FcRn-binding domain of said antigen-binding molecules at one or more of the positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436.
[29] A method for delaying the elimination of an antigen-binding molecule in a subject, comprising the step of introducing an amino acid substitution into an FcRn-binding domain of said antigen-binding molecule at one or more of the positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258 EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436.
[30] A method of prolonging the plasma retention time of an antigen-binding molecule, comprising the step of introducing an amino acid substitution into an FcRn-binding domain of said antigen-binding molecule at one or more of the positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258 EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436.
[31] A method for increasing the plasma antigen-elimination rate of an antigen-binding molecule, comprising the step of introducing an amino acid substitution into an FcRn-binding domain of said antigen-binding molecule at one or more of the positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258 EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436.
[32] A method for increasing the ability of an antigen-binding molecule to eliminate plasma antigen, comprising the step of introducing an amino acid substitution into an FcRn-binding domain of said antigen-binding molecule at one or more of the positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258 EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436.
[33] The method according to any one of [28] to [32], wherein further an amino acid substitution at position EU256 into the FcRn binding domain is introduced.
[34] The method according to any one of [28] to [33], wherein the method further comprises a step of introducing into the FcRn-binding domain an amino acid substitution at one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
[35] A method for producing antigen-binding molecules according to any one of [1] to
[25], which comprises the steps of
(a) selecting a parent FcRn-binding domain and altering the parent FcRn by introducing an amino acid substitution at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258 EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436;
(b) selecting an antigen-binding domain of an antigen-binding molecule and altering at least one amino acid in the antigen-binding domain in order to get a pH-dependent antigen-binding domain or a calcium-ion dependent antigen-binding domain;
(c) obtaining a gene encoding an antigen-binding molecule in which the human FcRn-binding domain and the antigen-binding domain prepared in (a) and (b) are linked and
(d) producing an antigen-binding molecule using the gene prepared in (c).
[36] The method according to [35], wherein in step a) further an amino acid substitution at position EU256 into the FcRn binding domain is introduced.
[37] The method according to any one of [35] to [36], wherein the method further comprises a step of introducing into the FcRn-binding domain an amino acid substitution at one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
[38] An antigen-binding molecule comprising a modified FcRn binding domain, wherein the modified FcRn binding domain comprises an amino acid substitution at one or more of the positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440, wherein the binding affinity of said antigen-binding molecule for a pre-existing anti-drug antibody (ADA) at a neutral pH is not significantly increased as compared to the binding affinity of antigen-binding molecule comprising an intact FcRn binding domain.
[39]. The antigen-binding molecule according to [38] wherein the antigen-binding molecule further has an increased binding affinity for an FcRn in the neutral or acidic pH ranges.
[40] The antigen-binding molecule according to [38] or [39], wherein the amino acid substituting one or more of the positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440 is selected from the group consisting of
a) at position EU387 an arginine;
b) at position EU422 a glutamic acid, an arginine, a serine, aspartic acid, lysine, threonine, or glutamine;
c) at position EU424 a glutamic acid, an arginine, a lysine, or asparagines;
d) at position EU426 an aspartic acid, a glutamine, an alanine, or a tyrosine;
e) at position EU433 an aspartic acid
f) at position EU436 a threonine
g) at position EU438 a glutamic acid, an arginine, a serine, or a lysine; and
h) at position EU440 a glutamic acid, an aspartic acid, or a glutamine.
[41] The antigen-binding molecule according to any one of [38] to [40], wherein the modified FcRn binding domain comprises an amino acid substitution at one or more positions or one of the combinations set forth in Table 10.
[42] The antigen-binding molecule according to any one of [38] to [40], wherein the modified FcRn binding domain comprises any one of the amino acid substitution or substitution combinations set forth in Table 11.
[43] The antigen-binding molecule according to any one of [39] to [42], wherein the modified FcRn binding domain further comprises an amino acid substitution at one or more positions of the FcRn binding domain selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU434, and EU436, wherein said substitutions confer an increase in FcRn binding activity in the neutral pH or acidic pH range.
[44] The antigen-binding molecule according to any one of [39] to [43], wherein the modified FcRn binding domain comprises amino acid substitutions at the FcRn binding domain positions
[45] The antigen-binding molecule according to [44], wherein the modified FcRn binding domain comprises amino acid substitutions
ii) a) M434H; b) M252Y/S254T/T256E; c) M428L/N434S; or d) T250Q and M428L (EU numbering).
[46] The antigen-binding molecule according to [45], wherein the modified FcRn binding domain comprises three or more amino acid substitutions wherein the three or more substitutions are one of the combinations set forth in Tables 13 and 15.
[47] The antigen-binding molecule according to any one of [39] to [42] wherein the modified FcRn binding domain comprises substitutions
a) at one or more of the positions selected from the group consisting of EU387, EU422, EU424, EU438, EU440, EU433, or at two or more positions wherein the two positions are one of the combinations of the group consisting of EU422/EU424, and EU438/EU440; and
b) two or more positions wherein the two positions are one of the combinations set forth in Table 9.
[48] The antigen-binding molecule according to [47], wherein the modified FcRn binding domain comprises three or more the amino acid substitutions wherein the three or more the amino acid substitutions are one of the combinations set forth in Tables 12 or 14.
[49] The antigen-binding molecule of any one of [39] to [48] wherein said antigen-binding molecule comprises a pH-dependent antigen-binding domain or a calcium ion-dependent antigen-binding domain.
[50] A method for decreasing the binding activity for a pre-existing ADA of an antigen-binding molecule comprising an FcRn binding domain having an increased binding activity for an FcRn at neutral or acidic pH and an increased binding activity for a pre-existing ADA at a neutral pH, said method comprising the steps of
a) providing an antigen-binding molecule with an FcRn binding domain having an increased binding activity for FcRn at neutral or acidic pH and an increased binding activity for a pre-existing ADA at a neutral pH; and
b) substituting an amino acid in the FcRn binding domain at one or more of the positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440 to yield an antigen-binding molecule with a modified FcRn binding domain.
[51] The method according to [50], wherein step b) comprises substituting an amino acid at three or more positions wherein the three or more positions are one of the combinations set forth in Table 10.
[52] The method according to [50], wherein step b) comprises introducing three or more the amino acid substitutions into the FcRn-binding domain wherein the three or more the amino acid substitutions are one of the combinations set forth in Table 11.
[53] A method for increasing the total number of antigens to which a single antigen-binding molecule can bind without significantly increasing the binding activity for a pre-existing ADA at neutral pH as compared to a parent antibody, said method comprising the steps of
a) providing an antigen-binding molecule comprising a parent FcRn binding domain,
b) altering the parent FcRn binding domain of step a) by substituting an amino acid in the amino acid sequence of the parent FcRn binding domain at one or more of the positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436; and
c) altering the modified FcRn-binding domain of step b) by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
[54] A method for facilitating the extracellular release of an antigen-free antigen-binding molecule taken up into cells in an antigen-bound form without significantly increasing the binding activity of said antigen-binding molecule for a pre-existing ADA at neutral pH as compared to a parent antibody, comprising the steps of
a) providing an antigen-binding molecule comprising a parent FcRn-binding domain,
b) altering the parent FcRn binding domain by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436, and EU428; and
c) altering the modified FcRn-binding domain of step b) by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
[55] A method for increasing the ability of an antigen-binding molecule to eliminate plasma antigen without significantly increasing the binding activity for pre-existing ADA at neutral pH compared to parent antibody, said method comprising the steps of
a) providing an antigen-binding molecule comprising a parent FcRn-binding domain,
b) altering the parent FcRn binding domain by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436, and EU428; and
c) altering the modified FcRn-binding domain of step b) by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
[56] A method for improving the pharmacokinetics of an antigen-binding molecule without significantly increasing the binding activity for a pre-existing ADA at neutral pH as compared to a parent antibody, said method comprising the steps of
a) providing an antigen-binding molecule comprising a parent FcRn-binding domain,
b) altering the parent FcRn-binding domain by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436; and
c) altering the modified FcRn-binding domain of step b) by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
[57] A method for reducing total or free antigen plasma concentration without significantly increasing the binding activity for a pre-existing ADA at neutral pH as compared to a parent antibody, said method comprising the steps of
a) providing an antigen-binding molecule comprising a parent FcRn-binding domain, wherein the antigen-binding molecule comprises an antigen-binding domain which can bind said antigen,
b) altering the parent FcRn-binding domain by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258 EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436; and
c) altering the modified FcRn-binding domain of step b) by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
[58] A method for producing an antigen-binding molecule comprising an FcRn binding domain having an increased binding activity for an FcRn at neutral or acidic pH and a decreased binding activity for an pre-existing ADA at neutral pH, said method comprising the steps of
(a) providing an FcRn binding domain having an increased binding activity for an FcRn at neutral or acidic pH ranges and pre-existing ADA at neutral pH ranges,
(b) substituting an amino acid at one or more of the positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440,
(c) selecting an antigen-binding domain of an antigen-binding molecule and altering at least one amino acid in the antigen-binding domain in order to get a pH-dependent antigen-binding domain, or selecting an calcium-ion dependent antigen-binding domain;
(d) obtaining a gene encoding an antigen-binding molecule in which the human FcRn-binding domain and the antigen-binding domain prepared in (a) and (b) are linked and
(e) producing an antigen-binding molecule using the gene prepared in (c), wherein said antigen-binding molecule produced has an increased binding activity for an FcRn at neutral or acidic pH and a decreased binding activity for an endogenous ADA at neutral pH as compared to a parent antigen-binding domain having an intact FcRn binding domain.
[59] The method according to [58], wherein the FcRn binding domain having an increased binding activity for FcRn and pre-existing ADA at neutral or acidic pH ranges and for pre-existing ADA in the neutral pH ranges comprises an amino acid substitution at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436.
[60] The method according to any one of [53] to [57], wherein the amino acid substitution introduced in step a) are at three or more positions wherein said three or more positions are one of the combinations set forth in Tables 4 to 7.
[61] The method according to any one of [53] to [60], wherein the amino acid substitutions introduced in step b) are at three or more positions wherein said three or more positions are one of the combinations set forth in Table 10.
Before the present materials and methods are described, it should be understood that these descriptions are merely illustrative only and not intended to be limiting. It should also be understood that the present invention is not limited to the particular sizes, shapes, dimensions, materials, methodologies, protocols, etc. described herein, as these may vary in accordance with routine experimentation and/or optimization. The terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope of the present invention that will be limited only by the appended claims. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. In case of conflict, the present specification, including definitions, will control.
The disclosure of each publication, patent or patent application mentioned in this specification is specifically incorporated by reference herein in its entirety. However, nothing herein is to be construed as an admission that the invention is not entitled to antedate such disclosure by virtue or prior invention.
The words “a”, “an”, and “the” as used herein mean “at least one” unless otherwise specifically indicated.
Studies described in the WO/2011/122011 have demonstrated that antigen-binding molecules (e.g. anti-IL6 receptor antibody) with increased binding to FcRn at pH7.4 are capable of eliminating antigen from plasma and decreasing the total antigen concentration in plasma, and that therefore, the efficiency of antigen elimination can be improved by pH-dependent antigen binding (bind to antigen within plasma at pH7.4 and dissociate the antigen within acidic endosome at pH6.0) or by ionized calcium concentration-dependent antigen binding (bind to antigen within plasma at high ionized calcium concentration and dissociate the antigen within the endosome at low ionized calcium concentration) (see
The present invention provides novel amino acid substitutions in the FcRn-binding domain that increase FcRn binding activity of an antigen-binding molecule in the acidic and neutral pH ranges, wherein the FcRn-binding activity in the neutral pH range is stronger than the one of an intact IgG or an antigen-binding molecule comprising an intact FcRn-binding domain (e.g. stronger than 3200 nM). The modified antigen-binding molecules can reduce the total antigen concentration in plasma after its administration more than a control antigen-binding molecule comprising the same antigen-binding domain but an intact human IgG FcRn-binding domain.
Fc receptors are proteins on the surface of immune cells such as natural killer cells, macrophages, neutrophils and mast cells. They bind to the Fc (Fragment, crystallizable) region of antibodies that are attached to infected cells or invading pathogens and stimulate phagocytic or cytotoxic cells to destroy microbes, or infected cells by antibody-mediated phagocytosis or antibody-dependent cell-mediated cytotoxicity.
There are several different types of Fc receptors, which are classified based on the type of antibody that they recognize. Herein, the term “FcRn” refers to the neonatal Fc receptor that binds IgG, is similar in structure to MHC class I protein and that, in humans, is encoded by the FCGRT gene.
The term “FcRn binding domain” as used herein refers to a protein domain that directly or indirectly binds to the FcRn. Preferably the FcRn is a mammalian FcRn, more preferably, a human FcRn. An FcRn binding domain binding directly to an FcRn is an antibody Fc region. Meanwhile, regions capable of binding to a polypeptide such as albumin or IgG, which has human FcRn-binding activity, can indirectly bind to human FcRn via albumin, IgG, or such. Thus, such a human FcRn-binding region may be a region that binds to a polypeptide having human FcRn-binding activity.
The term “Fc region” or “Fc region of an antigen-binding molecule” as used herein refers to an FcRn-binding domain that directly binds to FcRn, preferably to a mammalian FcRn, more preferably to a human FcRn. In particular, an Fc region is an Fc region of an antibody. Preferably, the Fc region is a mammalian Fc region, more preferably a human Fc region. In particular, the Fc region of the invention is an Fc region comprising the second and third constant domain of a human immunoglobulin (CH2 and CH3), more preferably the hinge, CH2 and CH3. Preferably, the immunoglobulin is an IgG. Preferably, the Fc region is an Fc region of human IgG1.
The present invention provides an antigen-binding molecule having a modified FcRn-binding domain wherein said antigen-binding molecule has an increased FcRn-binding activity in a neutral pH range as compared to an antigen-binding molecule having an intact FcRn-binding domain.
In particular, the present invention provides an antigen-binding molecule having a modified FcRn-binding domain with an amino acid substitution in an FcRn-binding domain at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258 EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436. The antigen-binding molecule of the present invention may also comprise substitutions at additional positions. For example, the antigen-binding molecule may comprise a substitution at position EU256 in addition to a substitution at the one or more positions mentioned above. Preferably, the amino acid at position EU256 is substituted with a glutamic acid.
The term “binding affinity” or “binding activity” refers to the strength of non-covalent interaction between two substances as measured by the dissociation constant (KD) of the complex formed by the two substances, unless expressly defined otherwise. A binding protein (or “ligand”) may, for example, have a KD of less than 10−5, 10−6, 10−7 or 10−8 M for a particular target molecule, e.g. the FcRn. Higher affinity binding of a binding ligand to a target a first pH range relative to a target at a second pH range can be indicated by a smaller numerical value KD for binding the target at the first pH range than the numerical value KD for binding the target at the second pH range. Differences in binding affinity can be at least 1.5, 2, 3, 4, 5, 10, 15, 20, 50, 70, 80, 100, 500, or 1000 fold. Binding affinity can be determined by a variety of methods including surface plasmon resonance, equilibrium dialysis, equilibrium binding, gel filtration, ELISA, or spectroscopy (e.g., using a fluorescence assay).
An increased binding affinity of an FcRn-binding domain for FcRn at a pH range corresponds to a measured increase of the FcRn-binding affinity as compared to the FcRn-binding affinity measured for an intact FcRn-binding domain. Differences in binding affinity of KD (intact)/KD (variant) is at least 1.5, 2, 3, 4, 5, 10, 15, 20, 50, 70, 80, 100, 500, or 1000 fold. An increased binding affinity of an FcRn-binding domain for FcRn can be in the acidic or neutral pH ranges.
The term “antigen-binding molecule comprising an intact FcRn binding domain” refers to an antigen-binding molecule comprising an unmodified FcRn-binding domain. The term “intact IgG FcRn-binding domain” as used herein refers to an unmodified FcRn-binding domain of a human IgG. In particular, the FcRn-binding domain is the FcRn-binding domain of an intact human IgG. Preferably, an intact FcRn-binding domain is an intact Fc region. The term “antibody comprising an intact Fc region” refers to an antibody comprising an unmodified Fc region. The antibody from which the unmodified Fc region originates is preferably an IgG. More preferably, it is a human IgG1, IgG2, IgG3 or IgG4, still more preferably, a human IgG1. In a particularly preferred embodiment of the present invention an antibody comprising an intact Fc region is an antibody comprising an unmodified Fc region. An antibody comprising an intact Fc region can be an intact human IgG.
The term “intact IgG” as used herein refers to an unmodified IgG and is not limited to a specific class of IgG. This means that human IgG1, IgG2, IgG3, IgG4 or their allotypic variants can be used as “intact human IgG” as long as it can bind to the human FcRn in the acidic pH range. Preferably, “intact IgG” is a human IgG1. Preferably, an intact IgG is an IgG which comprises a wild type Fc region.
In the context of the present invention, an increased FcRn-binding activity of antigen-binding molecule in the neutral pH ranges is preferably stronger than KD 3.2 micromolar. Preferably, the increased FcRn-binding activity in the neutral pH range is stronger than 700 nanomolar, more preferably stronger than 500 nanomolar and most preferably, stronger than 150 nanomolar.
An increased FcRn-binding activity of antigen-binding molecule of the present invention in the acidic pH ranges is generally an FcRn-binding activity in the range of about 2-fold to about 100-fold stronger than the FcRn-binding activity of an intact IgG. Preferably, the increased FcRn-binding activity of antigen-binding molecule in the acidic pH ranges is at least 10-fold stronger than the FcRn-binding activity of an intact IgG. More preferably, the increased FcRn-binding activity of an antigen-binding molecule of the present invention in the acidic pH range is at least 20-fold stronger than the FcRn-binding activity of an intact IgG.
The terms “neutral pH range” and “neutral pH” as used herein, typically refer to pH 6.7 to pH 10.0, preferably any pH value within pH 7.0 to pH 8.0, examples of which include pH 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, and 8.0. A particularly preferred acidic pH value is pH 7.4, which approximates plasma (blood) pH in vivo.
The terms “acidic pH range” and “acidic pH” as used herein, typically refer to pH 4.0 to pH 6.5, preferably to any pH value within pH 5.5 to pH 6.5, examples of which include pH 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, and 6.5. A particularly preferred acidic pH value ranges from pH 5.8 to pH 6.0, which approximates the pH in early endosome in vivo.
The amino acid positions referred to in this application, such as e.g. “EU387” or “position 387”, are, unless otherwise indicated, numbered according to a scheme called the EU numbering system (Kabat, E. A., T. T. Wu, H. M. Perry, K. S. Gottesman, C. Foeler. 1991. Sequences of Proteins of Immunological Interest. No. 91-3242 U.S. Public Health Services, National Institutes of Health, Bethesda) and refer to positions in an FcRn-binding domain, in particular in an Fc region. In a similar fashion, substitutions are indicated as for example “EU387R” or “EU440E”, wherein the number given after “EU” indicates the position of the substitution according the EU numbering, and the letter after the number is the substituted amino acid given in the one letter code. Substitutions may also be written as (amino acid 1)-position-(amino acid 2) whereby the first amino acid is the substituted amino acid and the second amino acid is the substituting amino acid at the specified position.
The terms “substitution” and “substitution of an amino acid” as used herein refer to a replacement of an amino acid in an amino acid sequence with another one, wherein the latter is different from the replaced amino acid. Methods for replacing an amino acid are well known to the skilled in the art and include, but are not limited to, mutations of the nucleotide sequence encoding the amino acid sequence.
More particularly, a substitution of an amino acid in an FcRn-binding domain refers to a replacement of an amino acid in reference to the amino acid sequence of a parent FcRn-binding domain. A modified FcRn-binding domain already having the desired substitutions is also included in the FcRn-binding domain of the present invention.
A parent FcRn-binding domain is an FcRn-binding domain having at the position EU238 an proline, at position EU250 a threonine, at position EU252 a methionine, at position EU254 a serine, at position EU255 an arginine, at position EU256 a threonine, at position EU258 a glutamic acid, at position EU286 an asparagine, at position EU307 a threonine, at position EU308 a valine, at position EU309 a leucine, at position EU311 a glutamine, at position EU315 an asparagine, at position EU387 a proline, at position EU422 a valine, at position EU424 a serine, at position EU426 a serine, at position EU428 a methionine, at position EU433 a histidine, at position EU434 an asparagine, at position EU436 a tyrosine, at position EU438 a glutamine, and at position EU440 a serine and no or low affinity for FcRn at neutral pH (weaker than 3200 nM). The parent FcRn-binding domain may comprise substitutions at other positions but preferably, the parent FcRn-binding domain is unmodified. Preferably, the parent FcRn binding domain is an Fc region (parent Fc region). Preferably, the parent Fc region is derived from a mammalian antibody; more preferably, the parent Fc region is the Fc region of a human antibody. An Fc region of a human antibody is herein referred to as a human Fc region.
A parent Fc region is, preferably an intact Fc region, more preferably a human intact Fc region. Preferably, the parent Fc region is the Fc region of an IgG, more preferably of a human IgG. Even more preferably, a parent Fc region is a human Fc region comprising the wild type hinge, wildtype CH2 and wildtype CH3 domain. In the context of the present invention, the term parent antibody refers to an antibody comprising a parent Fc region.
Parent antigen-binding molecules include, but are not limited to, receptor proteins (membrane-bound receptors and soluble receptors), antibodies that recognize a membrane antigen such as cell surface markers, and antibodies that recognize a soluble antigen such as cytokines
The term “parent antigen-binding molecule” as used herein refers to an antigen-binding molecule having a parent FcRn-binding domain. The origin of “parent antigen-binding molecule” is not limited and it may be obtained from any organism: of non-human animals or human. Preferably, the organism is selected from the group consisting of mouse, rat, guinea pig, hamster, gerbil, cat, rabbit, dog, goat, sheep, cow, horse, camel, and non-human primate. In another embodiment, “parent antigen-binding molecule” can also be obtained from cynomolgus monkey, marmoset, rhesus monkey, chimpanzee or human. The parent IgG may be a naturally occurring IgG, or a variant or engineered version of a naturally occurring IgG. Parent IgG may refer to the polypeptide itself, compositions that comprise the parent IgG, or the amino acid sequence that encodes it. It should be noted that “parent IgG” includes known commercial, recombinantly produced IgG as outlined below. Preferably, “parent IgG” is obtained from human IgG1 but not limited to a specific subclass of IgG. This means that human IgG1, IgG2, IgG3, or IgG4 can be appropriately used as “parent IgG”. In the a similar manner, any subclass of IgGs from any organisms described hereinbefore can be preferably used as “parent IgG”. Example of variant or engineered version of a naturally occurring IgG is described in Curr Opin Biotechnol. 2009 December; 20(6): 685-91, Curr Opin Immunol. 2008 August; 20(4): 460-70, Protein Eng Des Sel. 2010 April; 23(4): 195-202, WO 2009/086320, WO 2008/092117, WO 2007/041635 and WO 2006/105338, but not limited thereto.
An FcRn-binding domain or Fc region of the present invention may comprise a substitution at two or more positions which is herein referred to as a “combination” of substitutions. For example an Fc region defined by the combination “EU424/EU434/EU436” is an Fc region that comprises a substitution at the positions EU424, EU434 and EU436.
The substituting amino acid (the amino acid with which the amino acid in the parent FcRn-binding domain is substituted) may be any amino acid unless specifically mentioned herein, including but not limited to the group consisting of: alanine (Ala, A), arginine (arg, R), asparagines (asn, N), aspartic acid (asp, D), cysteine, (cys, C), glutamic acid (glu, E), glutamine (gln, Q), glycine (gly, G), histidine (his, H), isoleucine (ile, I), leucine (leu, L), lysine (lys, K), methionine (met, M), phenylalanine (phe, F), proline (pro, P), serine (ser, S), threonine (thr, T), tryptophan (trp, W), tyrosine (tyr, Y), and valine (val, V). Preferably, the substituting amino acid at any one of the positions EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440 is selected from the group consisting of: alanine (Ala, A), arginine (arg, R), glutamic acid (glu, E), glutamine (gln, Q), aspartic acid (asp, D), serine (ser, S), threonine (thr, T), tyrosine (tyr, Y), and lysine (lys, K).
In a preferred embodiment of the present invention, the antigen-binding molecule of the present invention has a modified FcRn-binding domain comprising an amino acid substitution with an amino acid different from the substituted one
a) at position EU252 and EU434, and
b) at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436.
The substituting amino acid may be any amino acid unless specifically mentioned herein. Preferred substituting amino acids for the positions EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436 are shown in Table 1.
Preferably, the modified FcRn-binding domain of the present invention comprises at least one of amino acids substitutions set forth in Table 1. It is possible to use the FcRn-binding domains without any alteration as long as they already have at least one of the above given amino acids at the specified position and said FcRn-binding domain has human FcRn-binding activity in the acidic and neutral pH ranges, whereby the FcRn-binding activity in the neutral pH ranges is increased.
In a preferred embodiment, the modified antigen-binding molecule of the present invention comprises a modification at three or more positions in the FcRn-binding domain, wherein the three or more positions are one of the combinations set forth in Tables 2, 4 to 7.
In a more preferred embodiment, the antigen-binding molecule of the present invention comprises three or more amino acid substitutions in a FcRn-binding domain, wherein the three or more substitutions are one of the combinations set forth in Tables 3, 12, 14, and 17 to 20.
Engineering an FcRn-binding domain by introducing substitutions may reduce the stability of the antigen-binding molecule (WO/2007/092772). Stability of a drug protein is critical for manufacturing pharmaceuticals, because proteins with poor stability tend to easily aggregate during storage. Therefore reduced stability caused by substitutions in the Fc region would make the development of a stable formulation difficult (WO2007/092772).
In addition, purity of a drug protein with regard to monomer species and high molecular weight species is also important for pharmaceutical development. Wild type IgG1 after protein A purification does not contain a significant amount of high molecular weight species, but engineering an FcRn-binding domain by introducing substitutions may result in a larger amount of high molecular weight species. In such a case, high molecular weight species need to be removed from bulk drug substances by a purification process which may be difficult in the development of the purification process.
Moreover, immunogenicity of a protein pharmaceutical in human is important, since the presence of anti-drug antibodies would result in clearance of the drug from the body and thus loss of therapeutic efficacy (IDrugs 2009; 12:233-7.). When substitutions are introduced into a wild type Fc domain (such as IgG1 Fc domain), the modified sequence becomes a non-human sequence. Such a modified sequence could be presented by MHC class II and therefore could be immunogenic in human patients.
Proteins will not be developed as a drug if they comprise Fc variants that exhibit poor stability and purity, and poor immunogenicity would hinder clinical development. It is therefore an objective of the present invention to improve the FcRn binding affinity at pH7.4 without
losing significant stability;
increasing the amount of high molecular weight species ratio, and
increasing the risk of immunogenicity (risk of anti-drug antibody formation)
Therefore, the present invention also provides an antigen-binding molecule comprising an amino acid substitution in the FcRn-binding domain at the positions EU252, EU434, EU307 and EU311, having a binding activity for the FcRn at pH 7 of more than 15 nM, a melting temperature Tm of 57.5 degrees C. or higher, an HMW of less than 2% and a low immunogenicity wherein a low immunogenicity is equivalent to a score of less than 500 determined with Epibase (Lonza).
Preferably, an antigen-binding molecule comprising an amino acid substitution in the FcRn-binding domain at four or more positions, wherein the four or more positions are one of the combinations of the group consisting of
b) EU252/EU434/EU307/EU311/EU436 in combination with one or more positions selected from the group consisting of EU286, EU308, and EU428.
The preferred combinations are set forth in Table 4.
Particular preferred are combinations a), g), h) and i) of Table 4.
In an even more preferred embodiment, the modified FcRn-binding domain comprises:
a) at position EU252 a tyrosine, at position EU286 a glutamic acid, at position EU307 a glutamine, at position EU311 an alanine, at position EU434 a tyrosine, and at position EU436 a valine; or
b) at position EU250 a valine, at position EU252 a tyrosine, at position EU307 a glutamine, at position EU308 a proline, at position EU311 an alanine, at position EU434 a tyrosine, and at position EU436 a valine; or
c) at position EU250 a valine, at position EU252 a tyrosine, at position EU286 a glutamic acid, at position EU307 a glutamine, at position EU308 proline, at position EU311 an alanine, at position EU434 a tyrosine, and at position EU436 a valine; or
d) at position EU250 a valine, at position EU252 a tyrosine, at position EU286 a glutamic acid, at position EU307 a glutamine, at position EU308 proline, at position EU311 an alanine, at position EU434 a tyrosine, and at position EU436 a valine.
The present invention also provides an antigen-binding molecule comprising an amino acid substitution in the FcRn-binding domain at three or more positions, wherein said three or more positions are one of the combinations of the group consisting of a) EU252/EU434/EU307/EU311; and b) EU252/EU434/EU308; wherein the FcRn-binding activity of said antigen-binding molecule at neutral pH is 15 to 50 nM, the Tm is higher than 60 degrees C., an HMW of less than 2% and wherein the antigen-binding molecule has a low immunogenicity whereby a low immunogenicity is equivalent to a score of less than 500 determined with Epibase (Lonza).
In a preferred embodiment, the amino acid substitutions are at four or more positions wherein the four or more positions are one of the combinations set forth in Table 5.
More preferred is an antigen-binding molecule comprising four or more amino acid substitutions wherein the four or more substitutions are one of the combinations of the group consisting of:
a) at position EU252 a tyrosine, at position EU286 a glutamic acid, at position EU307 a glutamine, at position EU311 an alanine and at position EU434 a tyrosine;
b) at position EU252 a tyrosine, at position EU254 a threonine, at position EU286 a glutamic acid, at position EU307 a glutamine, at position EU311 an alanine and at position EU434 a tyrosine;
c) at position EU252 a tyrosine, at position EU307 a glutamine, at position EU311 an alanine, at position EU434 a tyrosine and at position 436 an isoleucine;
d) at position EU252 a tyrosine, at position EU254 a threonine, at position EU286 a glutamic acid, at position EU307 a glutamine, at position EU311 an alanine, at position EU434 a tyrosine and at position EU436 an isoleucine;
e) at position EU250 a valine, at position EU252 a tyrosine, at position EU254 a threonine, at position EU308 a proline, at position EU434 a tyrosine and at position EU436 a valine;
f) at position EU250 a valine, at position EU252 a tyrosine, at position EU307 a glutamine, at position EU311 an alanine, at position EU434 a tyrosine and at position EU436 a valine;
g) at position EU252 a tyrosine, at position EU307 a glutamine, at position EU311 an alanine, at position EU434 a tyrosine and at position EU436 a valine;
h) at position EU250 a valine, at position EU252 a tyrosine, at position EU308 a proline, and at position EU434 a tyrosine; and
i) at position EU250 a valine, at position EU252 a tyrosine, at position 307 a glutamine, at position EU308 a proline, at position EU311 an alanine, and at position EU434 a tyrosine.
The present invention also provides an antigen-binding molecule comprising an amino acid substitution in the FcRn-binding domain
a) at the positions EU252/EU434; and
b) at position EU436 and/or at position EU254 and/or at position EU315; and having an FcRn-binding activity at pH 7 of 50 to 150 nM, a Tm higher than 63 degrees C., an HMW of less than 2% and a very low immunogenicity, wherein a very low immunogenicity is defined as a score of less than 250 determined with Epibase (Lonza).
Preferably, the amino acid substitutions are at three or more positions, wherein the three or more positions are one of the combinations set forth in Table 6.
In a more preferred embodiment, the modified antigen-binding molecule comprises three or more amino acid substitutions wherein the three or more substitutions are one of the combinations of the group consisting of:
a) at position EU252 a tyrosine, at position EU315 an aspartic acid, and at position EU434 a tyrosine;
b) at position EU252 a tyrosine, at position EU434 a tyrosine, and at position EU436 an isoleucine;
c) at position EU252 a tyrosine, at position EU434 a tyrosine, and at position EU436 a leucine;
d) at position EU252 a tyrosine, at position EU434 a tyrosine, and at position EU436 a valine; and
e) at position EU252 a tyrosine, at position EU254 a threonine, at position EU434 a tyrosine, and at position EU436 an isoleucine.
The present invention further provides an antigen-binding molecule that comprises an amino acid substitution in the FcRn-binding domain at three or more positions, wherein the three or more positions are one of the combinations set forth in Table 7. Said modified antigen-binding molecules have a binding activity for the FcRn at pH 7 of 150 to 700 nM, a Tm of higher than 66.5 degrees C., an HMW of less than 2% and a very low immunogenicity, wherein a very low immunogenicity is defined as a score of less than 250 determined with Epibase (Lonza).
Preferably, the modified antigen-binding molecules comprise three or more substitutions wherein the three or more substations are one of the combinations of the group consisting of
a) at position EU307 a glutamine, at position EU311 a histidine, and at position EU434 a tyrosine;
b) at position EU307 a glutamine, at position EU309 a glutamic acid, at position EU311 an alanine, at position EU434 a tyrosine;
c) at position EU307 a glutamine, at position EU309 a glutamic acid, at position EU311 a histidine, at position EU434 a tyrosine; or
d) at position EU250 a valine, at position EU252 a tyrosine, at position EU434 a tyrosine, at position EU436 a valine.
Substitutions of amino acids in an antibody can yield negative consequences, for example an increase in the immunogenicity of the therapeutic antibody which, in turn, can result in a cytokine storm and/or production of anti-drug antibodies (ADAs). Since ADAs can influence the efficacy and pharmacokinetics of therapeutic antibodies and sometimes lead to serious side effects, the clinical utility and efficacy of the therapeutic antibodies can be limited. Many factors influence the immunogenicity of therapeutic antibodies, and the presence of effector T-cell epitopes is one of the factors. Likewise, the presence of pre-existing antibodies against a therapeutic antibody can also be problematic. An example of such pre-existing antibody is the rheumatoid factor (RF), an auto-antibody (an antibody directed against a self protein) against the Fc portion of an antibody (i.e. IgG). The rheumatoid factor is found in particular in patients suffering of systemic lupus erythematosus (SLE) or rheumatoid arthritis. In arthritis patients, RF and IgG join to form immune complexes that contribute to the disease process. Recently, it was reported that a humanized anti-CD4 IgG1 antibody having an Asn434H is mutation elicited significant rheumatoid factor binding (Clin Pharmacol Ther. 2011 February; 89(2):283-90 (NPL 9)). Detailed studies have confirmed that the Asn434His mutation in the human IgG1 increased the binding of rheumatoid factor to the Fc region of the antibody compared to the parent human IgG1.
RF is a polyclonal auto-antibody against human IgG, and the epitope of the RF in the sequence of the human IgG varies among the clones, but the RF epitope seems to be located in the CH2/CH3 interface region as well as CH3 domain which could overlap with the FcRn binding epitope. Therefore, mutations to increase the binding affinity to FcRn at neutral pH might also increase the binding affinity to specific clone of RF.
Accordingly, it is preferable to increase the FcRn binding affinity at neutral and/or acidic pH without also increasing the binding affinity of the therapeutic antibody for a pre-existing antibody in the plasma at neutral pH.
Therefore, present invention also provides antigen-binding molecules comprising a modified FcRn-binding domain (preferably a modified Fc region), whereby the binding activity for a pre-existing ADA at a neutral pH is not significantly increased as compared to the binding affinity of an antigen-binding molecule comprising a wild type Fc region. The modified FcRn-binding domain (modified Fc region) preferably comprises an amino acid substitution at one or more of the positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
The above described substitutions are preferably introduced in an FcRn-binding domain or Fc region of an antigen-binding molecule that has increased affinity for the FcRn at neutral or acidic pH whereby said modified FcRn-binding domain or Fc region has an increased binding activity for a pre-existing ADA at neutral pH. The effect of the substitutions is a decrease of the binding activity for the pre-existing ADA. Therefore, in a preferred embodiment, a modified FcRn-binding domain or a modified Fc region of the present invention has a decreased binding activity to a pre-existing ADA as compared to an FcRn binding domain or an Fc region that has an increased binding activity to the FcRn at neutral or acidic pH, and an increased binding activity to the pre-existing anti-drug antibody in the neutral pH ranges. Preferably, an antigen-binding molecule having an increased binding activity at neutral pH for the FcRn and a pre-existing ADA are the antigen-binding molecules comprising an amino acid substitution at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436 as described above. It may also comprise a substitution at position EU256 in addition to a substitution at the one or more positions mentioned above. Preferably, the amino acid at position EU256 is substituted with a glutamic acid.
Therefore, the present invention also provides antigen-binding molecules comprising a modified Fc region which has an increased affinity for FcRn at neutral or acidic pH whereby the affinity for a pre-existing anti-drug antibody (ADA) at a neutral pH is not significantly increased compared to the binding affinity of antigen-binding molecule comprising a wild type Fc region. In a preferred embodiment, the present invention provides an antigen-binding molecule comprising a modified Fc region with an increased affinity for FcRn at neutral or acidic pH which comprises an amino acid substitution at one or more of the positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
Preferably, the antigen-binding molecule comprising a modified Fc region with an increased affinity for FcRn at neutral or acidic pH, whereby the binding activity at neutral pH for a pre-existing ADA is not significantly increased as compared to a control antigen-binding molecule, wherein the modified Fc region comprises an amino acid substitution at one or more of the positions selected from the substitutions as shown in Table 8.
The term “anti-drug antibody” and “ADA” as used herein refers to an endogenous antibody that has binding affinity for an epitope located on a therapeutic antibody and is thus capable of binding said therapeutic antibody. The term “pre-existing anti-drug antibody” and “pre-existing ADA” as used herein refers to an anti-drug antibody that is present and detectable in the blood of a patient prior to the administration of the therapeutic antibody to the patient. Preferably, the pre-existing ADA is a human antibody. In a particularly preferred embodiment, the pre-existing ADA is the rheumatoid factor, a polyclonal or monoclonal autoantibody against the Fc region of human IgG antibody. The epitopes of rheumatoid factor are located in the CH2/CH3 interface region as well as the CH3 domain but can vary among clones.
An antigen-binding molecule comprising an FcRn-binding domain region (or an Fc region) that has an increased affinity for FcRn at neutral or acidic pH and for a pre-existing anti-drug antibody at neutral pH is an antigen-binding molecule comprising an FcRn-binding domain (or an Fc region) that was modified to increase the binding affinity of the FcRn-binding domain (or Fc region) of an antigen-binding molecule for FcRn as compared to an antibody comprising an intact FcRn-binding domain (or intact Fc region). Modifications contemplated include, but are not limited to, substitutions of the amino acids in the amino acid sequence of the Fc portion of an antigen-binding domain. The antigen-binding molecule comprising an FcRn-binding domain or an Fc region, which has an increased binding activity for a) a pre-existing ADA in a neutral pH range and for FcRn at neutral (in case of an antigen-binding molecule of interest having an increased FcRn-binding activity at a neutral pH) or acidic pH (in case of an antigen-binding molecule of interest having an increased FcRn-binding activity at an acidic pH) is referred herein as “Reference Antibody”. A “Reference Antibody” is preferably the modified antigen-binding molecule before substituting an amino acid at one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440, more preferably before introducing any one of the substitutions set for in Table 8. A “Reference Antibody” may be an antigen-binding molecule comprising an amino acid substitution in an FcRn-binding domain at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258 EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436.
An example for a “Reference Antibody” having an increased FcRn-binding activity in the neutral pH ranges is an antigen-binding molecule comprising an Fc region with increased affinity for FcRn in the neutral pH ranges and having increased affinity for a pre-existing ADA at neutral pH comprising an amino acid substitution in the Fc region at
a) positions EU252 and EU434; and
b) one or more positions selected from the group consisting of EU238, EU250, EU254, EU255, EU256, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, and EU436.
More preferably, the antigen-binding molecule comprising an Fc region with increased affinity for FcRn in the neutral pH ranges and having increased affinity for a pre-existing ADA at neutral pH ranges comprises one of the combinations set forth in Table 9.
An example for a “Reference Antibody” having an increased FcRn-binding activity in the acidic pH ranges is an antigen-binding molecule comprising an Fc region with increased affinity for FcRn in the acidic pH ranges and having increased affinity for a pre-existing ADA at neutral pH ranges preferably comprise a substitution
i) at position EU434, or
ii) at two or more positions, wherein the two or more positions are one of the combinations of the group consisting of a) EU252/EU254/EU256; b) EU428/EU434; and c) EU250/EU428.
Preferably, the antigen-binding molecule comprising an Fc region with increased affinity at acidic pH ranges and having increased affinity for a pre-existing ADA at neutral pH comprises
i) the substitutions M434H; or
ii) one of the combinations of the group consisting of a) M252Y/S254T/T256E; b) M428L/N434S; and c) T250Q and M428L (EU numbering).
Preferably, the antigen-binding molecule comprising an Fc region which comprises one of the following substitutions or combinations a) M252Y/S254T/T256E, b) M428L/N434S or c) T250Q and M428L or d) M434H (EU numbering) has an increased binding activity to the FcRn at acidic pH without increasing the binding activity in the neutral pH ranges.
The binding activity of an Fc region of antigen-binding molecule for a pre-existing anti-drug antibody is expressed in the present application as an electrochemiluminescence (ECL) response at neutral pH; however, there are other suitable methods for determining the binding activity for a pre-existing ADA known to the skilled in the art. An ECL assay is for example described in Moxness et al (Clin Chem, 2005, 51:1983-85) and in the EXAMPLES of the present invention. Conditions used in the assay for determining the binding activity for a pre-existing ADA can be appropriately selected by those skilled in the art, and thus are not particularly limited.
An increased or higher binding affinity for a pre-existing ADA is increased as compared to the binding affinity for the pre-existing ADA of a Control Antigen-binding Molecule.
The term “Control Antigen-binding Molecule” as used herein refers to an antigen-binding molecule comprising an intact human Fc region, preferably an antibody or antibody derivative comprising an intact human Fc region.
The binding affinity for a pre-existing ADA may be assessed at any temperature from 10 degrees Celsius to 50 degrees Celsius. Preferably, a temperature at from 15 degrees Celsius to 40 degrees Celsius is employed in order to determine the binding affinity between human Fc region and human pre-existing ADA. More preferably, any temperature at from 20 degrees Celsius to 35 degrees Celsius, like any one of 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, and 35 degrees C. is employed in order to determine the binding affinity between human Fc region and human pre-existing ADA. Preferably, the temperature is between 20 and 25 degrees C., more preferably at 25 degrees C. In a preferred embodiment, the interaction between human pre-existing ADA and human Fc region is measured at pH 7.4 (or pH7.0) and at 25 degrees C.
In the context of the present invention, the term “an increased binding affinity for a pre-existing ADA” refers to a measured increase in binding affinity (i.e., KD) of an antigen-binding molecule of the present invention for a pre-existing ADA as compared to the binding affinity measured of a Control Antigen-binding Molecule for the pre-existing ADA. Such an increase in binding affinity for a pre-existing ADA can be observed in an individual patient or in a patient group.
The terms “patients” and “patient” as used herein, are not particularly limited and include all human beings who suffer from a disease and to whom in the course of a treatment a therapeutic antigen-binding molecule is administered. Preferably, a patient is a person suffering from an autoimmune disease. More preferably, a patient is a person suffering from an arthritic disease or systemic lupus erythematosus (SLE). Arthritic diseases include in particular rheumatoid arthritis.
In the context of the present invention, a significant increase of the binding activity for a pre-existing ADA in an individual patient corresponds to a measured increase of at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60% of the binding activity for a pre-existing ADA of a therapeutic antigen-binding molecule (i.e. a therapeutic antibody) comprising a modified Fc region in a patient as compared to the binding affinity for the pre-existing ADA of a Control Antigen-binding Molecule. Preferably the increase is at least 20%, more preferably the increase is at least 30%, even more preferably, it is at least 40% and most preferably the increase is at least 50% of the binding activity of a antigen-binding molecule comprising a modified Fc region as compared to the binding affinity for the pre-existing ADA of a control antigen-binding molecule. Alternatively, a significant increase in the binding activity of an antigen-binding molecule for a pre-existing ADA in a patient is preferably an ECL response to the antigen-binding molecule of more than 250, preferably to an ECL of at least 500, more preferably to an ECL of at least 1000, most preferably to an ECL of at least 2000. More preferably, the increase is an increase as compared with the ECL response of a Control Antigen-binding Molecule of less than 500 (preferably of less than 250). Preferred ranges between an the binding activity for a pre-existing ADA of the Control Antigen-binding Molecule and that of an antigen-binding molecule with a modified Fc region are in particular ECL responses from less than 250 to at least 250, from less than 250 to at least 500, from less than 500 to 500 or more, from less than 500 to 1000 or more, and from less than 500 to at least 2000.
The increase in the binding activity for a pre-existing ADA may also correspond to a measured increase in the portion of patients in a patient population having an ECL response of at least 500 (preferably at least 250) to an the antigen-binding molecule with an increased binding activity to a) the FcRn at neutral or acidic pH and b) an pre-existing ADA at neutral pH as compared to the portion of patients having an ECL response of at least 500 (preferably at least 250) at neutral pH to a control antigen-binding molecule. A “significant” increase in the portion of patients in a patient population is preferably an increase of at least 10%, at least 20%, at least 30%, at least 40%, at least 50% patients having a ECL response of the therapeutic antigen-binding molecule comprising a modified Fc region to the rheumatoid factor at neutral pH of 500 or less (preferably of 250 or more) compared to the portion of patients having an ECL response to a Control Antigen-binding Molecule. Preferably the increase is at least 20%, more preferably at least 30%, even more preferably, it is at least 40% and most preferably it is 50% or more.
In the context of the present invention, a decrease in the binding affinity for a pre-existing ADA refers to a measured decrease in binding activity (i.e., KD or ECL response) as compared to the binding activity measured for a Reference Antibody, Such a decrease of binding affinity for a pre-existing ADA can be observed in an individual patient or in a patient group. The decrease of the affinity of a therapeutic antigen-binding molecule for a pre-existing ADA at neutral pH in an individual patient refers to a measured decrease at neutral pH in the binding activity as compared to the binding activity measured for a Reference Antibody for the pre-existing ADA at neutral pH in said patient. Preferably, a significant decrease in an individual patient is a measured decrease at neutral pH of at least 10%, at least 20%, at least 30%, at least 40%, at least 50% in the binding activity of the modified antigen-binding molecule for a pre-existing ADA as compared to the binding activity of a Reference Antibody for a pre-existing ADA at neutral pH. More preferably, the decrease is at least 30%, even more preferably, it is 40% and most preferably it is 50% or more as compared to a Reference antibody.
Alternatively, the significant decrease in an individual patient of a modified antigen-binding molecule's binding activity for a pre-existing ADA may be measured as a decrease of the ECL response of said antigen-binding molecule as compared with the ECL response of a Reference Antibody from an ECL response of 500 or more, (preferably, from an ECL of 1000 or more, most preferably from an ECL of 2000 or more), to less than 500, preferably of less than 250. Preferred decreases are from an ECL response of 500 or more to an ECL response of less than 500, more preferably from at least 250 to less than 250, even more preferably from at least 500 to less than 250. Preferred ranges are, in particular, from at least 250 to less than 250, from at least 500 to less than 250, from at least 1000 to less than 250, from at least 2000 to less than 250, from at least 500 to less than 500, from at least 1000 to less than 500, and from at least 2000 to less than 500.
The decrease may also be a decrease in the percentage of patients in a patient population that has an increased binding of their pre-existing ADA to the modified antigen-binding molecule in neutral pH ranges. In other words, the decrease may be measured as a decrease of the percentage of people having an ECL response of their pre-existing ADA to a modified antigen-binding molecule as compared to the ECL response to a Reference Antibody. Preferably, a decrease may be a decrease of at least 10%, at least 20%, at least 30%, at least 40%, at least 50% in the portion of patients in a patient population in which the therapeutic antigen-binding molecule has an increased binding activity to a pre-existing ADA as compared to the portion of patients having an increased binding activity of the Reference antibody to the pre-existing ADA, wherein the increased binding is expressed as an ECL response of 500 or more, preferably 250 or more. Preferably the decrease is at least 20%, more preferably the decrease is at least 30%, even more preferably, it is 40% and most preferably it is 50% or more.
In a preferred embodiment, a therapeutic antigen-binding molecule of the present invention has low binding activity for a pre-existing ADA at a neutral pH. In particular, the binding activity of a modified antigen-binding molecule of the present invention for a pre-existing ADA at a neutral pH is preferably significantly decreased compared to the binding activity of a Reference Antibody for a pre-existing ADA at neutral pH. More preferably, the binding activity of a modified antigen-binding molecule of the present invention for a pre-existing ADA at a neutral pH is not significantly increased as compared to the binding affinity of a Control Antigen-binding Molecule (has about the same binding activity for a pre-existing ADA as Control Antigen-binding Molecule). A low binding activity or baseline affinity for a pre-existing ADA is preferably an ECL response of less than 500 in a individual patient. Preferably, a ECL response is less than 250. In a patient population, a low binding activity for a pre-existing ADA is an ECL response of less than 500 in 90% of the patients in the patient population, more preferably in 95% of the patients, most preferably in 98% of the patients.
In a more preferred embodiment, the antigen-binding molecule comprising a modified FcRn-binding domain with an increased affinity for FcRn at neutral or acidic pH, wherein the binding activity at neutral pH for a pre-existing ADA is not significantly increased as compared to a control antigen-binding molecule, whereby the modified FcRn-binding domain of the present invention comprises a substitution at one or more of the positions or combinations set forth in Table 10.
In a more preferred embodiment, the antigen-binding molecule of the present invention comprises a modified FcRn-binding domain having one or more of the substitutions or combinations set forth in Table 11.
In a preferred embodiment, the antigen-binding molecule comprising a modified FcRn-binding domain with a) an increased affinity for FcRn at neutral or acidic pH b) a binding affinity for a pre-existing ADA at neutral pH which is not significantly increased compared to a Control Antigen-binding Molecule, said antigen-binding molecule comprises any one of the combinations of substitutions set forth in Table 12.
Also preferably, an antigen-binding molecule having an increased FcRn binding activity at neutral pH ranges and a binding affinity for a pre-existing ADA at neutral pH that is not significantly increased as compared to an antigen-binding molecule comprising a wild type Fc region comprises an amino acid substitution in an FcRn-binding domain at
a) one or more of the positions selected from the group consisting: EU387, EU422, EU424, EU438, EU440, EU433, or b) at two or more positions, wherein the two or more positions are the combination EU422/EU424; or EU438/EU440. More preferably, the substitutions are selected from among the substitutions set forth in Table 11.
Even more preferably, an FcRn-binding domain of an antigen-binding molecule having an increased binding activity for the FcRn at neutral pH ranges and a binding affinity for a pre-existing ADA at neutral pH that is not significantly increased as compared to an antigen-binding molecule comprising a wild type Fc region comprising any one of the substitution combinations set forth in Table 12. In particular, preferred modified antigen-binding molecules having an increased FcRn-binding activity in neutral pH ranges whereby the binding affinity at neutral pH for a pre-existing ADA is not significantly increased comprises three or more substitutions in the FcRn-binding domain, wherein the three or more substitutions are any one of the combinations no. (2) to (26) and (28) to (59) set forth in Table 12.
The present invention also provides an antigen-binding molecule having an increased binding activity for the FcRn at acidic pH ranges and a binding affinity for a pre-existing ADA at neutral pH that is not significantly increased as compared to a Control Antigen-binding Molecule, comprising an amino acid substitution at a) position EU424 or b) position EU438/EU440.
More preferably, the substitutions are selected among a) EU424N and EU438R/EU440E.
Preferably, an FcRn-binding domain of an antigen-binding molecule that has an increased binding activity for the FcRn at acidic pH ranges and a binding affinity for a pre-existing ADA at neutral pH that is not significantly increased as compared to a Control Antigen-binding Molecule, comprises one of the substitution combinations set forth in Table 13. More preferably, the antigen-binding molecule having an increased FcRn-binding activity in the acidic pH ranges whereby the binding affinity for a pre-existing ADA at neutral pH that is not significantly increased as compared to a Control Antigen-binding Molecule, comprises any one of the substitution combinations no. (13) to (28) set forth in Table 13.
In addition to a substitution at any one of the positions EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440, the Fc region of the present invention may also comprise further substitution of an amino acid at one or more of the following positions: EU248, EU249, EU250, EU251, EU252, EU253, EU254, EU255, EU256, EU257, EU305, EU306, EU307, EU308, EU309, EU310, EU311, EU312, EU313, EU314, EU342, EU343, EU344, EU345, EU346, EU347, EU348, EU349, EU350, EU351, EU352, EU380, EU381, EU382, EU383, EU384, EU385, EU386, EU388, EU414, EU415, EU416, EU417, EU418, EU419, EU420, EU421, EU423, EU425, EU427, EU428, EU429, EU430, EU431, EU432, EU433, EU434, EU435, EU436, EU437, EU441, EU442, EU443, and EU444.
Substituting an Fc region at any one of these positions may reduce the binding affinity for a pre-existing ADA, in particular for the rheumatoid factor, without negatively affecting the binding affinity for FcRn.
Furthermore, the methods of the present invention may further comprise the step of substituting the Fc region of the antigen-binding molecule as described above at one or more of the following positions:
EU248, EU249, EU250, EU251, EU252, EU253, EU254, EU255, EU256, EU257, EU305, EU306, EU307, EU308, EU309, EU310, EU311, EU312, EU313, EU314, EU342, EU343, EU344, EU345, EU346, EU347, EU348, EU349, EU350, EU351, EU352, EU380, EU381, EU382, EU383, EU384, EU385, EU386, EU388, EU414, EU415, EU416, EU417, EU418, EU419, EU420, EU421, EU423, EU425, EU427, EU428, EU429, EU430, EU431, EU432, EU433, EU434, EU435, EU436, EU437, EU441, EU442, EU443, and EU444.
Binding to Fc gamma receptors or complement proteins may also cause undesired effects (e.g. inappropriate platelet activation). A modified antigen-binding molecule that does not bind effector receptors such as Fc gamma RIIa receptor is safer and/or more effective. Therefore, in a preferred embodiment, the modified antigen-binding molecules of the present invention additionally have a weak binding activity for an effector receptor or do not bind to an effector receptor. Examples of an effector receptor include but are not limited to activating Fc gamma receptors, in particular Fc gamma receptor I, Fc gamma receptor II and Fc gamma receptor III. Fc gamma receptor I includes Fc gamma receptor Ia, Fc gamma receptor Ib, and Fc gamma receptor Ic, and subtypes thereof. Fc gamma receptor II includes Fc gamma receptor IIa (which has two allotypes R131 and H131) and Fc gamma receptor IIb. Fc gamma receptor III includes Fc gamma receptor IIIa (which has two allotypes: V158 and F158) and Fc gamma receptor IIIb (which has two allotypes: Fc gamma IIIb-NA1 and Fc gamma IIIb-NA2). Antibodies that have a weak binding activity for effector receptors or do not bind to them are for examples antibodies comprising a silent Fc region or antibodies without an Fc region (e.g. Fab, F(ab)′2, scFv, sc(Fv)2, diabodies).
Examples for Fc regions having a weak or no binding activity for effector receptors are e.g. described in Strohl et al. (Current Opinion in Biotechnology (2009) 20(6), 685-691). In particular it describes for example deglycosylated Fc regions (N297A, N297Q), and examples of a silent Fc region, which are Fc regions engineered for silenced (or immunosuppressive) effector functionality (IgG1-L234A/L235A, IgG1-H268Q/A330S/P331S, IgG1-C226S/C229S, IgG1-C226S/C229S/E233P/L234V/L235A, IgG1-L234F/L235E/P331S, IgG2-V234A/G237A, IgG2-H268QN309L/A330S/A331S, IgG4-L235A/G237A/E318A, IgG4-L236E). WO2008/092117 discloses antibodies comprising silent Fc regions that comprise the substitutions G236R/L328R, L235G/G236R, N325A/L328R, or N325L/L328R (positions according to the EU numbering system). Furthermore, WO 2000/042072 discloses antibodies comprising silent Fc regions which comprise substitutions at one or more of the positions EU233, EU234, EU235, and EU237. WO 2009/011941 discloses antibodies comprising silent Fc regions which comprise deletion of residues from EU231 to EU238. Davis et al (Journal of Rheumatology (2007) 34(11): 2204-2210) discloses antibodies comprising silent Fc regions which comprise the substitutions C220S/C226S/C229S/P238S. Shields et al (Journal of Biological Chemistry (2001) 276 (9), 6591-6604) discloses antibodies comprising silent Fc regions which comprise the substitution D265A.
The term “weak binding for effector receptors” refers to a binding activity that is 95% or less, preferably 90% or less, 85% or less, 80% or less, 75% or less, more preferably 70% or less, 65% or less, 60% or less, 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1% or less of the binding activity of an intact IgG (or an antibody comprising an intact Fc region) for the effector receptor. The binding activity to an Fc gamma R preferably reduced by a factor of at least about 10 fold or more, about 50-fold or more, about 100-fold or more as compared with the binding activity of an intact IgG (or an antibody comprising an intact Fc region) for the effector receptor.
A silent Fc region is a modified Fc region comprising one or more amino acid substitutions, insertions, additions and/or deletions which reduce the binding for an effector receptor as compared to an intact Fc region. The binding activity for an effector receptor may be so much reduced that the Fc region does not bind an effector receptor anymore. Examples of a silent Fc region include but are not limited to Fc regions which comprise an amino acid substitution at one or more of the positions selected from the group consisting of: EU234, EU235, EU236, EU237, EU238, EU239, EU265, EU266, EU267, EU269, EU270, EU271, EU295, EU296, EU297, EU298, EU300, EU324, EU325, EU327, EU328, EU329, EU331, and EU332.
In particular, a silent Fc region has a substitution at one or more the positions selected from the group consisting of EU234, EU235, EU236, EU237, EU238, EU239, EU265, EU266, EU267, EU269, EU270, EU271, EU295, EU296, EU297, EU298, EU300, EU324, EU325, EU327, EU328, EU329, EU331, and EU332 with an amino acid selected from the list below. Preferably, a silent Fc region has a substitution at one or more positions selected from the group consisting of EU235, EU237, EU238, EU239, EU270, EU298, EU325, and EU329 with an amino acid selected from the list below. The amino acid at position EU234 is preferably replaced with one of an amino acid selected from the group consisting of: Ala, Arg, Asn, Asp, Gln, Glu, Gly, His, Lys, Met, Phe, Pro, Ser, and Thr.
The amino acid at position EU235 is preferably replaced with one of an amino acid selected from the group consisting of: Ala, Asn, Asp, Gln, Glu, Gly, His, Ile, Lys, Met, Pro, Ser, Thr, Val and Arg.
The amino acid at position EU236 is preferably replaced with one of an amino acid selected from the group consisting of: Arg, Asn, Gln, His, Leu, Lys, Met, Phe, Pro and Tyr.
The amino acid at position EU237 is preferably replaced with one of an amino acid selected from the group consisting of: Ala, Asn, Asp, Gln, Glu, His, Ile, Leu, Lys, Met, Pro, Ser, Thr, Val, Tyr and Arg.
The amino acid at position EU238 is preferably replaced with one of an amino acid selected from the group consisting of: Ala, Asn, Gln, Glu, Gly, His, Ile, Lys, Thr, Trp and Arg.
The amino acid at position EU239 is preferably replaced with one of an amino acid selected from the group consisting of: Gln, His, Lys, Phe, Pro, Trp, Tyr and Arg.
The amino acid at position EU265 is preferably replaced with one of an amino acid selected from the group consisting of: Ala, Arg, Asn, Gln, Gly, His, Ile, Leu, Lys, Met, Phe, Ser, Thr, Trp, Tyr and Val.
The amino acid at position EU266 is preferably replaced with one of an amino acid selected from the group consisting of: Ala, Arg, Asn, Asp, Gln, Glu, Gly, His, Lys, Phe, Pro, Ser, Thr, Trp and Tyr.
The amino acid at position EU267 is preferably replaced with one of an amino acid selected from the group consisting of: Arg, His, Lys, Phe, Pro, Trp and Tyr.
The amino acid at position EU269 is preferably replaced with one of an amino acid selected from the group consisting of: Ala, Arg, Asn, Gln, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, Tyr and Val.
The amino acid at position EU270 is preferably replaced with one of an amino acid selected from the group consisting of: Ala, Arg, Asn, Gln, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, Tyr and Val.
The amino acid at position EU271 is preferably replaced with one of an amino acid selected from the group consisting of: Arg, His, Phe, Ser, Thr, Trp and Tyr.
The amino acid at position EU295 is preferably replaced with one of an amino acid selected from the group consisting of: Arg, Asn, Asp, Gly, His, Phe, Ser, Trp and Tyr.
The amino acid at position EU296 is preferably replaced with one of an amino acid selected from the group consisting of: Arg, Gly, Lys and Pro.
The amino acid at position EU297 is preferably replaced with Ala,
The amino acid at position EU298 is preferably replaced with one of an amino acid selected from the group consisting of: Arg, Gly, Lys, Pro, Trp and Tyr.
The amino acid at position EU300 is preferably replaced with one of an amino acid selected from the group consisting of: Arg, Lys and Pro.
The amino acid at position EU324 is preferably replaced with Lys or Pro.
The amino acid at position EU325 is preferably replaced with one of an amino acid selected from the group consisting of: Ala, Arg, Gly, His, Ile, Lys, Phe, Pro, Thr, Trp, Tyr, and Val.
The amino acid at position EU327 is preferably replaced with one of an amino acid selected from the group consisting of: Arg, Gln, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, Tyr and Val.
The amino acid at position EU328 is preferably replaced with one of an amino acid selected from the group consisting of: Arg, Asn, Gly, His, Lys and Pro.
The amino acid at position EU329 is preferably replaced with one of an amino acid selected from the group consisting of: Asn, Asp, Gln, Glu, Gly, His, Ile, Leu, Lys, Met, Phe, Ser, Thr, Trp, Tyr, Val and Arg.
The amino acid at position EU330 is preferably replaced with Pro or Ser.
The amino acid at position EU331 is preferably replaced with one of an amino acid selected from the group consisting of: Arg, Gly and Lys.
The amino acid at position EU332 is preferably replaced with one of an amino acid selected from the group consisting of: Arg, Lys and Pro.
Preferably, a silent Fc region comprises a substitution at position EU235 with Lys or Arg, EU237 with Lys or Arg, EU238 with Lys or Arg, EU239 with Lys or Arg, EU270 with Phe, EU298 with Gly, EU325 with Gly or EU329 with Lys or Arg. More preferably, a silent Fc region comprises a substitution at position EU235 with arginine and at position EU239 with lysine. More preferably, it comprises the substitutions L235R/S239K.
Furthermore, the modified antigen-binding molecules of the present invention are preferably deglycosylated. More preferably, the modified antigen-binding molecule of the present invention comprises a mutation at a heavy chain glycosylation site to prevent glycosylation at the site such as e.g. described in WO2005/03175. Thus, in a preferred embodiment of the present invention, the modified aglycosyl antigen-binding molecules are prepared by modifying the heavy chain glycosylation site, i.e., introducing the substitution N297Q or N297A (position according to EU numbering system), and expressing the protein in an appropriate host cell. For introducing a substitution a method as described in the EXAMPLES can be used.
In a specific embodiment of the present invention, the modified antigen-binding molecules of the present invention thereof have a weak binding activity for a complement protein or do not bind to a complement protein. Preferably, the complement protein is C1q. A weak binding activity for a complement protein is preferably a binding activity for a complement protein which is reduced by a factor of about 10 fold or more, about 50-fold or more, about 100-fold or more as compared to the binding activity for a complement protein of an intact IgG or an antibody comprising an intact Fc region. The binding activity of an Fc region for a complement protein can be reduced by modification of the amino acid sequence such as amino acid substitutions, insertions, additions and/or deletions
In a preferred embodiment of the present invention, the antigen-binding molecule has an increased FcRn-binding affinity in the acidic or neutral pH and has a weak or no binding activity for an effector receptor and/or a complement protein. Preferably, such an antigen-binding molecule comprises a substitution in the FcRn-binding domain at
a) one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436, and
b) at one or more positions selected from the group consisting of: EU234, EU235, EU236, EU237, EU238, EU239, EU265, EU266, EU267, EU269, EU270, EU271, EU295, EU296, EU297 EU298, EU300, EU324, EU325, EU327, EU328, EU329, EU331, and EU332 (according to the EU numbering system). More preferably, the modified antigen-binding molecule of the present invention having a reduced or no binding activity for effector receptors and/or complement proteins comprises one or more substitutions in the Fc regions selected from the group consisting of a substitution at position EU235 with Lys or Arg, at position EU237 with Lys or Arg, at position EU238 with Lys or Arg, at position EU239 with Lys or Arg, at position EU270 with Phe, EU298 with Gly, at position EU325 with Gly and at position EU329 with Lys or Arg. Even more preferably, it comprises a substitution in the Fc region at position EU235 with Arg and at position EU239 with Lys. And even more preferably, it comprises the substitution combination L235R/S239K in the Fc region.
Preferably, such antigen-binding molecules have also no significantly increased binding activity for a pre-existing ADA. Therefore, the antigen-binding molecule of the present invention having a reduced or no binding activity for effector receptor(s) and/or complement proteins further comprises an amino acid substitutions at c) one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440. In a more preferred embodiment of the present invention, the modified antigen-binding molecules comprise three or more amino acid substitutions in the FcRn-binding domain, wherein the three or more substitutions are one of the combinations set forth in Tables 14 and 15.
Furthermore, the antigen-binding molecule of the present invention comprises in addition to the modifications described above, at the position EU257 of the FcRn-binding domain not an amino acid selected from the group consisting of: alanine, valine, isoleucine, leucine, and threonine,
and/or at the position EU252 of the FcRn-binding domain not a tryptophan. In other words, the preferred antigen-binding molecule of the present invention comprises in addition to any of the modifications described above at positions EU257 an alanine, a valine, an isoleucine, aleucine, a threonine, an arginine, an asparagine, an aspartic acid, a cysteine, a glutamic acid, a glutamine, a glycine, a histidine, a lysine, a methione, a phenylalanine, a proline, a serine, a tryptophan, or a tyrosine, and at position EU252 an arginine, an asparagine, an aspartic acid, a cysteine, a glutamic acid, a glutamine, a glycine, a histidine, a lysine, a methione, a phenylalanine, a proline, a serine, or a tyrosine
Also preferred is a modified FcRn-binding domain which comprises in addition to the substitutions at any one of the herein mentioned positions or combinations of positions, at position EU239 a lysine and/or at position EU270 a phenylalanine.
The antigen-binding molecules of the present invention are not particularly limited, as long as they include an antigen-binding domain having a binding activity specific to a target antigen and an FcRn-binding domain of the present invention. Preferred antigen-binding domains comprise, for example, domains having an antigen-binding region of an antibody. The antigen-binding region of an antibody comprises, for example, CDRs. The antigen-binding region of an antibody may contain all six CDRs from the whole antibody, or one, two, or more CDRs. The antigen-binding region of antibody comprise amino acid deletions, substitutions, additions, and/or insertions, or it may comprise a portion of CDR.
On the other hand, antigen-binding molecules of the present invention include antigen-binding molecules that have an antagonistic activity (antagonistic antigen-binding molecules), antigen-binding molecules that have an agonistic activity (agonistic antigen-binding molecule), and molecules having cytotoxicity. In a preferred embodiment, the antigen-binding molecules are antagonistic antigen-binding molecules, in particular, antagonistic antigen-binding molecules that recognize an antigen such as a receptor or cytokine.
The antigen-binding molecule of the present invention is preferably an antibody. The antibodies preferred in the context of the present invention include, for example, IgG antibodies. When the antibody to be used is an IgG antibody, the type of IgG is not particularly limited; thus, the IgG may belong to any isotype (subclass) such as IgG1, IgG2, IgG3, or IgG4. For a human IgG1, IgG2, IgG3, or IgG4 constant region, gene polymorphisms (allotypes) are described in “Sequences of proteins of immunological interest, NIH Publication No. 91-3242”. These allotypes can also be used for constant region in this application. Especially, for human IgG1, both of the amino acids Asp-Glu-Leu (DEL) and Glu-Glu-Met (EEM) can be used for residues in 356-358 in EU numbering. Similarly, for human immunoglobulin kappa constant region, gene polymorphisms (allotypes) are described in “Sequences of proteins of immunological interest, NIH Publication No. 91-3242”. These allotypes can also be used for constant region in this application. Furthermore, the antigen-binding molecules of the present invention may include antibody constant region, and amino acid mutations may be introduced into the constant region. Amino acid mutations to be introduced include, for example, those potentiate or impair the binding to Fcgamma receptor (Proc Natl Acad Sci USA. 2006 Mar. 14; 103(11): 4005-10), but are not limited to these examples. Alternatively, it is also possible to alter the pH-dependent binding by selecting an appropriate constant region such as of IgG2 (WO09125825).
When an antigen-binding molecule of the present invention is an antibody, the antibody may be derived from any animal, such as a mouse, human, rat, rabbit, goat, or camel. Preferably, the antibody is a human antibody. Furthermore, the antibody may be an altered antibody, for example, a chimeric antibody, and in particular, an altered antibody that comprises an amino acid substitution in the sequence of a humanized antibody, etc. The category of antibodies contemplated by the present invention also include bispecific antibodies, antibody modification products linked with various molecules, and polypeptides that comprise antibody fragments (particularly immunogenic and/or immunoreactive antibody fragments). In a preferred embodiment, the antigen-binding molecule is a monoclonal antibody.
“Chimeric antibodies” are antibodies prepared by combining sequences derived from different animals. Specifically, a chimeric antibody includes, for example, antibodies having heavy and light chain variable (V) regions from a mouse antibody and heavy and light chain constant (C) regions from a human antibody. Methods for generating chimeric antibodies are known. In the case of a human-mouse chimeric antibody, for example, a DNA encoding an antibody V region may be linked to a DNA encoding a human antibody C region; this can be inserted into an expression vector and introduced into a host to produce the chimeric antibody.
“Humanized antibodies”, also referred to as reshaped human antibodies, are known in the art as antibodies in which complementarity determining regions (CDRs) of an antibody derived from a nonhuman mammal, for example, a mouse, are transplanted into the CDRs of a human antibody. Methods for identifying CDRs are known (Kabat et al., Sequence of Proteins of Immunological Interest (1987), National Institute of Health, Bethesda, Md.; Chothia et al., Nature (1989) 342: 877). General genetic recombination technologies suitable for this purpose are also known (see European Patent Application EP 125023; and WO 96/02576). Humanized antibodies can be produced by known methods, for example, the CDR of a mouse antibody can be determined, and a DNA encoding an antibody in which the CDR is linked to the framework region (FR) of a human antibody is obtained. Humanized antibodies can then be produced using a system that uses conventional expression vectors. Such DNAs can be synthesized by PCR, using as primers several oligonucleotides prepared to have portions that overlap with the end regions of both the CDR and FR (see the method described in WO 98/13388). Human antibody FRs linked via CDRs are selected such that the CDRs form a suitable antigen binding site. If required, amino acids in the FRs of an antibody variable region may be altered so that the CDRs of the reshaped human antibody can form a suitable antigen binding site (Sato et al., Cancer Res. (1993) 53: 10.01-6). Amino acid residues in the FRs that can be altered include portions that directly bind to an antigen via non-covalent bonds (Amit et al., Science (1986) 233: 747-53), portions that influence or have an effect on the CDR structure (Chothia et al., J. Mol. Biol. (1987) 196: 901-17), and portions involved in VH-VL interactions (EP 239400).
When the antigen-binding molecules of the present invention are chimeric antibodies or humanized antibodies, the constant regions of these antibodies are preferably derived from human antibodies. For example, C-gamma1, C-gamma2, C-gamma3, and C-gamma4 can be used for the H chain, while C-kappa and C-lambda can be used for the L chain. Moreover, if required, amino acid mutations may be introduced into the human antibody C region to enhance or lower the binding to Fc-gamma receptor or to improve antibody stability or productivity. A chimeric antibody of the present invention preferably includes a variable region of an antibody derived from a nonhuman mammal and a constant region derived from a human antibody. Meanwhile, a humanized antibody preferably includes CDRs of an antibody derived from a nonhuman mammal and FRs and C regions derived from a human antibody. The constant regions derived from human antibodies preferably include a human FcRn-binding region. Such antibodies include, for example, IgGs (IgG1, IgG2, IgG3, and IgG4). The constant regions used for the humanized antibodies of the present invention may be constant regions of antibodies of any isotype. A constant region derived from human IgG1 is preferably used, though it is not limited thereto. The FRs derived from a human antibody, which are used for the humanized antibodies, are not particularly limited either, and may be derived from an antibody of any isotype.
The term “bispecific antibody” as used herein refers to an antibody that has, in the same antibody molecule, variable regions that recognize different epitopes. A bispecific antibody may be an antibody that recognizes two or more different antigens, or an antibody that recognizes two or more different epitopes on a same antigen.
Furthermore, polypeptides including antibody fragments may be, for example, scFv-Fc (WO 2005/037989), dAb-Fc, and Fc fusion proteins. Antibody fragments in such polypeptides can be for example Fab fragments, F(ab′)2 fragments, scFvs (Nat. Biotechnol. 2005 September; 23(9): 1126-36), domain antibodies (dAbs) (WO 2004/058821, WO 2003/002609), Fc region can be used as a human FcRn-binding domain when a molecule includes an Fc region. Alternatively, an FcRn-binding domain may be fused to these molecules.
Further, antigen-binding molecules that are applicable to the present invention can be or can comprise antibody-like molecules (e.g. a fusion protein of an Fc region of the present invention with an antibody-like molecule). An antibody-like molecule (scaffold molecule, peptide molecule) is a molecule that can exhibit functions by binding to a target molecule (Current Opinion in Biotechnology (2006) 17: 653-658; Current Opinion in Biotechnology (2007) 18: 1-10; Current Opinion in Structural Biology (1997) 7: 463-469; Protein Science (2006) 15: 14-27), and includes, for example, DARPins (WO 2002/020565), Affibody (WO 1995/001937), Avimer (WO 2004/044011; WO 2005/040229), and Adnectin (WO 2002/032925). If these antibody-like molecules can bind to target molecules in a pH-dependent or calcium-dependent manner and/or have human FcRn-binding activity in the neutral pH range, it is possible to facilitate antigen uptake into cells by antigen-binding molecules, facilitate the reduction of plasma antigen concentration by administering antigen-binding molecules, and improve pharmacokinetics of the antigen-binding molecules, and increase the number of antigens to which a single antigen-binding molecule can bind.
Furthermore, the antigen-binding molecule can be a protein resulting from fusion between an FcRn-binding domain of the present invention and a receptor protein that binds to a target including a ligand, and includes, for example, TNFR-Fc fusion proteins, IL1R-Fc fusion proteins, VEGFR-Fc fusion proteins, and CTLA4-Fc fusion proteins (Nat Med. 2003, January; 9(1): 47-52; BioDrugs. (2006) 20(3): 151-60). If these receptor-FcRn-binding domain fusion proteins bind to a target molecule including a ligand in a pH-dependent or calcium-dependent manner in addition to having FcRn-binding activity in the neutral pH range, it is possible to facilitate antigen uptake into cells by antigen-binding molecules, facilitate the reduction of plasma antigen concentration by administering antigen-binding molecules, and improve pharmacokinetics of the antigen-binding molecules, and increase the number of antigens to which a single antigen-binding molecule can bind. A receptor protein is appropriately designed and modified so as to include a binding domain of the receptor protein to a target including a ligand. As referred to the examples hereinbefore (i.e. TNFR-Fc fusion proteins, IL1R-Fc fusion proteins, VEGFR-Fc fusion proteins and CTLA4-Fc fusion proteins) a soluble receptor molecule comprising an extracellular domain of those receptor proteins that is required for binding to those targets including ligands is particularly preferred. Such designed and modified receptor molecules are referred to as artificial receptors in the present invention. Methods for designing and modifying a receptor molecule to construct an artificial receptor molecule are known and indeed conventional in the art.
Furthermore, the antibodies of the present invention can have modified sugar chains. Antibodies with modified sugar chains include, for example, antibodies with modified glycosylation (WO 99/54342), antibodies that are deficient in fucose that is added to the sugar chain (WO 00/61739; WO 02/31140; WO 2006/067847; WO2006/067913), and antibodies having sugar chains with bisecting GlcNAc (WO 02/79255).
According to the Journal of Immunology (2009) 182: 7663-7671, the human FcRn-binding activity of intact human IgG1 in the acidic pH range (pH 6.0) is KD 1.7 micromolar (microM), while in the neutral pH range the activity is almost undetectable. Thus, in a preferred embodiment, the antigen-binding molecule of the present invention includes antigen-binding molecules whose human FcRn-binding activity in the acidic pH range is stronger than KD 1.7 micromolar and is identical or stronger in the neutral pH range than that of intact human IgG. In a more preferred embodiment its binding activity for a pre-existing ADA in the neutral pH ranges is not significantly increased compared to intact IgG1. The above KD values are determined by the method described in the Journal of Immunology (2009) 182: 7663-7671 (by immobilizing the antigen-binding molecule onto a chip and loading human FcRn as an analyte).
Dissociation constant (KD) can be used as a value of human FcRn-binding activity. However, the human FcRn-binding activity of intact human IgG has little human FcRn-binding activity in the neutral pH range (pH 7.4). Accordingly, it is often difficult to calculate the activity as KD. Methods for assessing whether the human FcRn-binding activity is higher than that of intact human IgG at pH 7.4 include assessment methods by comparing the intensities of Biacore response after loading analytes at the same concentration. Specifically, when the response after loading a human FcRn chip immobilized with an antigen-binding molecule at pH 7.4 is stronger than the response after loading human FcRn onto a chip immobilized with intact human IgG at pH 7.4, the human FcRn-binding activity of the antigen-binding molecule is judged to be higher than that of intact human IgG at pH 7.4.
In the context of the present invention, pH 7.0 can be used as the neutral pH range. Using pH 7.0 as a neutral pH can facilitate weak interaction between human FcRn and FcRn-binding domain. As a temperature employed in the assay condition, a binding affinity may be assessed at any temperature from 10 degrees Celsius to 50 degrees Celsius. Preferably, a temperature ranging from 15 degrees Celsius to 40 degrees Celsius is employed in order to determine the binding affinity between human FcRn-binding domain and human FcRn. More preferably, any temperature ranging from 20 degrees Celsius to 35 degrees Celsius, like any one of 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, and 35 degrees C. is also employed in order to determine the binding affinity between human FcRn-binding domain and human FcRn. A temperature at 25 degrees C. described in EXAMPLE 5 of WO2011/122011 is one example for the embodiment of this invention. In a preferred embodiment, an interaction between human FcRn and FcRn-binding domain can be measured at pH 7.0 and at 25 degrees C. as described in EXAMPLE 5 of WO2011/122011. Binding affinity of antigen-binding molecule to human FcRn can be measured by Biacore as described in EXAMPLE 5 of WO2011/122011.
Preferably the binding affinity at neutral pH ranges is measured at pH 7.4, which is close to in vivo plasma (blood) pH. pH 7.0 can be used as an alternative to pH 7.4 when it is difficult to assess the binding affinity between human FcRn-binding domain and human FcRn due its low affinity at pH 7.4. Preferably the binding affinity at acidic pH ranges is measured at pH 6.0, which is close to the pH in early endosome in vivo. As a temperature employed in the assay condition, a binding affinity between human FcRn-binding domain and human FcRn may be assessed at any temperature from 10 degrees C. to 50 degrees C. Preferably, a temperature from 15 degrees C. to 40 degrees C. is employed in order to determine the binding affinity between human FcRn-binding domain and human FcRn. More preferably, any temperature at from 20 degrees C. to 35 degrees C., like any one of 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, and 35 degrees C. is also employed in order to determine the binding affinity between human FcRn-binding domain and human FcRn. A temperature at 25 degrees C. is described for example in Example 5 of WO2011/122011 and in the EXAMPLES of this invention.
An intact human IgG1, IgG2, IgG3 or IgG4 is preferably used as the reference intact human IgG to be compared with the antigen-binding molecules for their human FcRn binding activity or in vivo activity. Preferably, an antigen-binding molecule that comprises the same antigen-binding domain as the antigen-binding molecule of the interest and an intact human IgG Fc region as a human FcRn-binding domain is used as reference. More preferably, an intact human IgG1 is used as reference intact human IgG for comparing its human FcRn binding activity or in vivo activity with the human FcRn binding activity or in vivo activity of an antigen-binding molecule of the present invention.
Conditions used in the assay for the antigen-binding or human FcRn-binding activity other than pH can be appropriately selected by those skilled in the art, and the conditions are not particularly limited. For example, the conditions of using MES buffer at 37 degrees C. as described in WO 2009/125825 may be used to determine the activity. In another embodiment, Na-phosphate buffer at 25 degrees C. as described in Example 4 or 5 of WO2011/122011 may be used to determine the activity. Meanwhile, the antigen-binding activity and human FcRn-binding activity of antigen-binding molecule can be determined by methods known to those skilled in the art, for example, using Biacore (GE Healthcare) or such. When the antigen is a soluble antigen, the activity of an antigen-binding molecule to bind to the soluble antigen can be determined by loading the antigen as an analyte onto a chip immobilized with the antigen-binding molecule. Alternatively, when the antigen is a membrane-type antigen, the activity of the antigen-binding molecule to bind to the membrane-type antigen can be determined by loading the antigen-binding molecule as an analyte onto an antigen-immobilized chip. The human FcRn-binding activity of an antigen-binding molecule can be determined by loading human FcRn or the antigen-binding molecule as an analyte onto a chip immobilized with the antigen-binding molecule or human FcRn, respectively.
The present invention provides an antigen-binding molecule of the present invention that comprises an antigen-binding domain and a human Fc region having an increased FcRn-binding activity in the neutral pH ranges. Preferably, its binding activity for a pre-existing ADA in the neutral pH ranges is not significantly increased. The FcRn-binding activity of such antigen-binding molecule in the neutral pH ranges is preferably stronger than KD 3.2 micromolar. More preferably, the FcRn-binding activity in the neutral pH range is stronger than 700 nanomolar, even more preferably stronger than 500 nanomolar and most preferably, stronger than 150 nanomolar. Preferably, the antigen-binding molecule has an increased human FcRn-binding activity in the neutral pH ranges and an antigen-binding activity that is lower in the acidic pH range than in the neutral pH range or that is lower at a low calcium concentration than at a high calcium concentration condition. Preferably, binding activity of such an antigen-binding molecule for a pre-existing ADA in the neutral pH ranges is not significantly increased. The present invention also provides an antigen-binding molecule of the present invention that comprises an antigen-binding domain and a human FcRn-binding domain, wherein its human FcRn-binding activity is increased in the neutral pH ranges, further wherein the human FcRn-binding activity in the neutral pH ranges is 28-fold stronger than that of an intact human IgG, more preferably, the human FcRn-binding activity in the neutral pH ranges is 38-fold stronger than that of an intact human IgG. Preferably, binding activity of such an antigen-binding molecule for a pre-existing ADA in the neutral pH ranges is not significantly increased. The antigen-binding molecule of the present invention with an increased FcRn-binding activity in the neutral pH ranges. Preferably a binding activity for a pre-existing ADA in the neutral pH ranges that is not significantly increased preferably, has human FcRn-binding activity at pH 7.0 and at 25 degrees C. which is 28-fold stronger, preferably 38-fold stronger, than intact human IgG than intact human IgG. Alternatively, the human FcRn-binding activity of the antigen-binding molecule with an increased FcRn binding activity at pH 7.0 and at 25 degrees C. is preferably stronger than KD 3.2 micromolar. More preferably, the FcRn-binding activity in at pH 7.0 and at 25 degrees Celsius is stronger than 700 nanomolar, more preferably stronger than 500 nanomolar and most preferably, stronger than 150 nanomolar.
The present invention provides an antigen-binding molecule of the present invention, comprising an antigen-binding domain and a human Fc region of the present invention, with an increased FcRn-binding activity in the acidic pH ranges and a binding activity for a pre-existing ADA in the neutral pH ranges that is not significantly increased. The present invention also provides an antigen-binding molecule of the present invention comprising an antigen-binding domain and a human FcRn-binding domain having an increased human FcRn-binding activity in the acidic pH range and a binding activity for a pre-existing ADA in the neutral pH ranges that is not significantly increased as compared to the binding activity for a pre-existing ADA of an intact IgG, wherein the human FcRn-binding activity in the acidic pH ranges is in the range of about 2-fold to about 100-fold stronger than the human FcRn-binding activity of an intact human IgG. Preferably, the human FcRn-binding activity of antigen-binding molecule of the present invention in the acidic pH ranges is at least 10-fold stronger than the FcRn-binding activity of an intact human IgG, more preferably, the human FcRn-binding activity in the acidic pH ranges is at least 20-fold stronger than that of an intact human IgG. The antigen-binding molecule of the present invention with an increased FcRn-binding activity in the acidic pH ranges whereby its binding activity for a pre-existing ADA in the neutral pH ranges is not significantly increased has human FcRn-binding activity at pH 6.0 and at 25 degrees C. which is 10-fold stronger, preferably 20-fold stronger, than intact human IgG.
The antigen-binding molecules of the present invention may have an increased FcRn-binding activity in the neutral pH ranges as well as an antigen-binding activity in the acidic pH range that is lower than the antigen-binding activity in the neutral pH range or an antigen-binding activity at a low calcium concentration that is lower than the antigen-binding activity at a high calcium concentration condition. Specific examples of such antigen-binding molecules include those that have a higher binding activity for human FcRn at pH 7.4 than an intact Ig, and whose antigen-binding activity is lower at pH 5.8 than at pH 7.4 which are presumed to be the in vivo pH of the early endosome and plasma, respectively. An antigen-binding molecule whose antigen-binding activity is lower at pH 5.8 than at pH 7.4 can also be referred to as an antigen-binding molecule whose antigen-binding activity is stronger at pH 7.4 than at pH 5.8. The value of KD (pH 5.8)/KD (pH 7.4), which is a ratio of dissociation constant (KD) against an antigen at pH 5.8 and pH 7.4, is 1.5, 2, 3, 4, 5, 10, 15, 20, 50, 70, 80, 100, 500, 1000 or 10,000 preferably 2 or greater, more preferably 10 or greater, and still more preferably 40 or greater. The upper limit of the KD (pH 5.8)/KD (pH 7.4) value is not particularly limited, and may be any value, for example, 400, 1,000, or 10,000, as long as production is possible using the technologies of those skilled in the art. Also preferred are antigen-binding molecules of the present invention that have an increased FcRn-binding activity in the acidic pH ranges, as well as a lower antigen-binding activity in the acidic pH range than that in the neutral pH range or a lower antigen-binding activity at a low calcium concentration than that at a high calcium concentration. Preferably, binding activity of such an antigen-binding molecule for a pre-existing ADA in the neutral pH ranges is not significantly increased. Specific examples of such antigen-binding molecules include those that have a higher binding activity for human FcRn at pH 5.8 to pH 6.0 than an IgG, which is presumed to be the in vivo pH of the early endosome and whose antigen-binding activity is lower at pH 5.8 than at pH 7.4. An antigen-binding molecule whose antigen-binding activity is lower at pH 5.8 than at pH 7.4 can also be referred to as an antigen-binding molecule whose antigen-binding activity is weaker at pH 5.8 than at pH 7.4. Preferably, an antigen-binding molecule having an increased binding activity for FcRn in the acidic pH ranges has stronger FcRn-binding activity than intact human IgG in the neutral pH range.
The modified FcRn-binding domains of the present invention are applicable to any antigen-binding molecules, regardless of the type of target antigen.
An antigen-binding molecule of the present invention may have other properties. For example, it may be an agonistic or antagonistic antigen-binding molecule, provided that it has a) the requisite increased human FcRn-binding activity neutral pH ranges, or b) an increased human FcRn-binding activity for in the acidic ranges and its binding activity for a pre-existing ADA is not significantly increased. Preferably, the antigen-binding activity of such an antigen-binding molecule is lower in the acidic pH range than in the neutral pH range. Preferred antigen-binding molecules of the present invention include, for example, antagonistic antigen-binding molecules. Such an antagonistic antigen-binding molecule is typically an antigen-binding molecule that inhibits receptor-mediated intracellular signaling by blocking the binding between ligand (agonist) and receptor.
Meanwhile, an antigen-binding molecule of the present invention may recognize any antigen. Specific antigens recognized by an antigen-binding molecule of the present invention include, for example, the above-described receptor proteins (membrane-bound receptors and soluble receptors), membrane antigens such as cell-surface markers, and soluble antigens such as cytokines Such antigens include, for example, the antigens described below.
Antigen-binding molecules of the present invention comprising an antigen-binding domain can utilize a difference of pH as an environmental difference between plasma and endosome for differential binding affinity of an antigen binding molecule to an antigen at plasma and endosome (strong binding at plasma and weak binding at endosome). Since environmental difference between plasma and endosome is not limited to a difference of pH, pH dependent binding property on binding of an antigen-binding molecule to an antigen can be substituted by utilizing other factors whose concentration is different within the plasma and the endosome, such as for example the ionized calcium concentration. Such factor may also be used to generate an antibody that binds to the antigen within plasma but dissociates the antigen within endosome. Therefore, the present invention also includes an antigen-binding molecule comprising a human FcRn-binding domain, whose human FcRn-binding activity is increased in the neutral pH ranges and whose antigen-binding activity in the endosome is lower as compared to the plasma. Preferably, the binding activity of these antigen-binding molecules in the neutral pH ranges for a pre-existing ADA is not significantly increased. The human FcRn-binding activity of such an antigen-binding molecule is in the plasma stronger than that of intact human IgG, and further the antigen-binding domain of such an antigen-binding molecule has a lower affinity for the antigen inside the endosome than in the plasma. Preferably, the antigen-binding domain is an antigen-binding domain whose antigen-binding activity in the acidic pH range is lower than that in the neutral pH range (pH-dependent antigen-binding domain) or an antigen-binding domain whose antigen-binding activity is lower with a low calcium concentration than under a high calcium concentration condition (calcium-concentration-dependent antigen-binding domain). The present invention also includes an antigen-binding molecule with a human FcRn-binding domain, which has an increased human FcRn-binding activity in the acidic pH ranges, and said antigen-binding molecule further comprises an antigen-binding domain which has a lower affinity for the antigen inside the endosome than in the plasma, such that the human FcRn-binding activity of the antigen-binding molecule in the endosome is stronger than that of intact human IgG, and the antigen-binding activity of the antigen-binding molecule in the endosome is stronger than in the plasma. Preferably, the binding activity of these antigen-binding molecules in the neutral pH ranges for a pre-existing ADA is not significantly increased. Preferably, the antigen-binding domain is an antigen-binding domain whose antigen-binding activity in the acidic pH range is lower than that in the neutral pH range (pH-dependent antigen-binding domain) or an antigen-binding domain whose antigen-binding activity is lower with a low calcium concentration than under a high calcium concentration condition (calcium-concentration-dependent antigen-binding domain).
The antigen-binding molecules of the present invention facilitate antigen uptake into cells, in particular when the antigen-binding molecules of the present invention comprising an antigen-binding domain that is a pH-dependent antigen-binding domain or a calcium-concentration-dependent antigen-binding domain. The antigen-binding molecules are easily dissociated from the antigen in the endosome, and then released to the outside of the cell by binding to human FcRn. The antigen-binding molecules of the present invention are presumed to bind easily to an antigen in the plasma again. Thus, for example, when the antigen-binding molecule of the present invention is a neutralizing antigen-binding molecule, reduction of the plasma antigen concentration can be facilitated by administering the molecule.
Preferably, the antigen-binding domain of the antigen-binding molecule has a decreased affinity for the antigen at an acidic pH or at low calcium ion concentration. More preferably, the antigen-binding domain is a pH-dependent antigen-binding domain or a ionized calcium concentration dependent antigen-binding domain described herein.
A) pH-Dependent Antigen-Binding Domain,
Furthermore, the antigen-binding molecule of the present invention comprises preferably a pH-dependent antigen-binding domain whose antigen-binding activity in the acidic pH range is lower than that in the neutral pH range. Said antigen-binding molecule has preferably a lower antigen-binding activity in the acidic pH range than in the neutral pH range. The binding activity ratio is not limited, provided that the antigen-binding activity is lower in the acidic pH range than in the neutral pH range. In a preferred embodiment, the antigen-binding molecules of the present invention include antigen-binding molecules whose antigen-binding activity at pH 7.4 is twice or higher than that at pH 5.8, preferably the antigen-binding activity at pH 7.4 is ten times or higher than that at pH 5.8. In a still more preferred embodiment, the antigen-binding molecules of the present invention include antigen-binding molecules whose antigen-binding activity at pH 7.4 is 40 times or higher than that at pH 5.8.
Specific examples of antigen-binding molecules of the present invention include the embodiments described in WO 2009/125825. In a preferred embodiment, the antigen-binding molecule of the present invention comprising a pH-dependent antigen-binding domain has an antigen-binding activity at pH 5.8 that is lower than that at pH 7.4, wherein the value of KD (pH5.8)/KD (pH7.4), which is a ratio of KD for the antigen at pH 5.8 and that at pH 7.4, is preferably 2 or greater, more preferably 10 or greater, and still more preferably 40 or greater. The upper limit of the KD (pH5.8)/KD (pH7.4) value is not particularly limited, and may be any value, for example, 400, 1,000, or 10,000, as long as production is possible using the technologies of those skilled in the art.
In another preferred embodiment, the antigen-binding molecule of the present invention whose antigen-binding activity at pH 5.8 is lower than that at pH 7.4, has a value of KD (pH5.8)/KD (pH7.4), which is a ratio of the KD for the antigen at pH 5.8 and the KD for the antigen at pH 7.4, that is 2 or greater, more preferably 5 or greater, even more preferably 10 or greater, and still more preferably 30 or greater. The upper limit of the KD (pH5.8)/KD (pH7.4) value is not particularly limited, and may be any value, for example, 50, 100, or 200, provided that the production is possible using the technologies of those skilled in the art.
Conditions other than the pH at which the antigen-binding activity, binding activity for a pre-existing ADA and human FcRn-binding activity are measured can be appropriately selected by those skilled in the art, and such conditions are not particularly limited; however, the measurements can be carried out, for example, under conditions of MES buffer and at 37 degrees C., as described in the Examples. Furthermore, the antigen-binding activity of an antigen-binding molecule can be determined by methods known to those skilled in the art, for example, using Biacore T100 (GE Healthcare) or the like, as described in the Examples.
Methods for reducing (impairing) the antigen-binding activity of an antigen-binding molecule in the acidic pH range to less than that the antigen-binding activity in the neutral pH range (methods for conferring the pH-dependent binding ability) are not particularly limited and suitable methods are known to the skilled in the art. WO 2009/125825, for example, describes methods for reducing (impairing) the antigen-binding activity in the acidic pH range to less than that in the neutral pH range by substituting histidine for an amino acid in the antigen-binding domain or inserting histidine into the antigen-binding domain. It is further known that an antibody can be conferred with a pH-dependent antigen-binding activity by substituting histidine for an amino acid in the antibody (FEBS Letter (1992) 309(1): 85-88). Other suitable methods include methods for substituting non-natural amino acids for amino acids in the antigen-binding domain or inserting non-natural amino acids into the antigen-binding domain. It is known that pKa can be artificially adjusted by using non-natural amino acids (Angew. Chem. Int. Ed. 2005, 44, 34; Chem Soc Rev. 2004 Sep. 10, 33 (7): 422-30; Amino Acids. (1999) 16(3-4): 345-79). Any non-natural amino acid may be used in context of the present invention. In fact, it is possible to use non-natural amino acids known to those skilled in the art.
In a preferred embodiment, the antigen-binding molecule of the present invention comprising an antigen-binding domain with an antigen-binding activity that is lower in the acidic pH range than that in the neutral pH range, includes antigen-binding molecules in which at least one amino acid in the antigen-binding molecule is replaced with histidine or a non-natural amino acid, and/or in which at least one histidine or a non-natural amino acid has been inserted. The site into which the histidine or non-natural amino acid mutation is introduced is not particularly limited and may be any site deemed suitable by those of skilled in the art, provided that the resultant antigen-binding activity in the acidic pH range is weaker than that in the neutral pH range (the KD (in the acidic pH range)/KD (in the neutral pH range) value is greater or the kd (in the acidic pH range)/kd (in the neutral pH range) value is greater) as compared to before substitution. Examples include variable regions and CDRs of an antibody in the case the antigen-binding molecule is an antibody. The number of amino acids to be replaced with histidine or non-natural amino acid and the number of amino acids to be inserted can be appropriately determined by those skilled in the art. One amino acid may be replaced with histidine or non-natural amino acid, or one amino acid may be inserted, or two or more amino acids may be replaced with histidine or non-natural amino acids, or two or more amino acids may be inserted. Moreover, apart from the substitutions of histidine or non-natural amino acid or insertion of histidine or of non-natural amino acid, deletion, addition, insertion, and/or substitution and such of other amino acids may also be simultaneously carried out. Substitutions of histidine or non-natural amino acid or insertion of histidine or of non-natural amino acid may be carried out at random using a method such as histidine scanning, which uses histidine instead of alanine in alanine scanning which is known to those skilled in the art. Antigen-binding molecules whose KD (pH5.8)/KD (pH7.4) or kd (pH5.8)/kd (pH7.4) is increased as compared to before mutation can be selected from antigen-binding molecules into which histidine or non-natural amino acid mutation has been introduced at random.
Preferably, the binding activity of the antigen-binding domain at neutral pH (i.e. pH7.4) is maintained. When the antigen-binding activity of an antigen-binding molecule before histidine or non-natural amino acid mutation is set as 100%, the antigen-binding activity of the antigen-binding molecule at pH7.4 after histidine or non-natural amino acid mutation is at least 10% or more, preferably 50% or more, more preferably 80% or more, and still more preferably 90% or more. The antigen-binding activity at pH 7.4 after histidine or non-natural amino acid mutation may be stronger than the antigen-binding activity at pH 7.4 before histidine or non-natural amino acid mutation. When the antigen-binding activity of the antigen-binding molecule is decreased due to substitution or insertion of histidine or non-natural amino acid, the antigen-binding activity may be adjusted by introducing substitution, deletion, addition, and/or insertion and such of one or more amino acids into the antigen-binding molecule so that the antigen-binding activity becomes equivalent to that before histidine substitution or insertion.
In the context of present invention, when the antigen-binding molecule is an antibody, possible sites of histidine or non-natural amino acid substitution include, for example, CDR sequences and sequences responsible for the CDR structure of an antibody, including, for example, the sites described in WO 2009/125825.
Furthermore, the present invention provides antigen-binding molecules having substitution of histidine or a non-natural amino acid for at least one amino acid at one of the following sites
Heavy chain: H27, H31, H32, H33, H35, H50, H58, H59, H61, H62, H63, H64, H65, H99, H100b, and H102
Light chain: L24, L27, L28, L32, L53, L54, L56, L90, L92, and L94
H32, H61, L53, L90, and L94 of these alteration sites, are presumed to be highly general alteration sites. The amino acid positions are shown according to Kabat numbering (Kabat et al., Sequences of Immunological Interest. 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991)). The Kabat numbering system is generally used when referring to a residue in the variable domain (approximately residues 1-107 of the light chain and residues 1-113 of the heavy chain). Specifically preferred combinations of sites for histidine or non-natural amino acid substitutions include, for example, the combination of H27, H31, and H35; the combination of H27, H31, H32, H35, H58, H62, and H102; the combination of L32 and L53; and the combination of L28, L32, and L53. Furthermore, preferred combinations of substitutions sites in the heavy and light chains include, for example, the combination of H27, H31, L32, and L53.
When the antigen is an IL-6 receptor (for example, human IL-6 receptor), preferred alteration sites include but are not particularly limited to the following:
Heavy chain: H27, H31, H32, H35, H50, H58, H61, H62, H63, H64, H65, H100b, and H102
Light chain: L24, L27, L28, L32, L53, L56, L90, L92, and L94
Specifically preferred combinations of sites for histidine or non-natural amino acid substitution include, for example, the combination of H27, H31, and H35; the combination of H27, H31, H32, H35, H58, H62, and H102; the combination of L32 and L53; and the combination of L28, L32, and L53. Furthermore, preferred combinations of substitution sites in the heavy and light chains include, for example, the combination of H27, H31, L32, and L53.
Histidine or non-natural amino acids can be substituted at one or more of the positions mentioned above.
Alternatively, the antigen-binding molecule of the present invention may comprise an antibody constant region that was altered so that the antigen-binding activity at pH 5.8 is lower than that at pH 7.4. Methods for altering antibody constant regions contained in the antigen-binding molecules are known and indeed conventional to the skilled in the art. Specific examples of antibody constant regions after alteration include the constant regions described in the Examples in WO 2009/125825 (SEQ ID NOs: 11, 12, 13, and 14).
Meanwhile, methods for altering an antibody constant region include, for example, methods for assessing various constant region isotypes (IgG1, IgG2, IgG3, and IgG4) and selecting isotypes that reduce the antigen-binding activity in the acidic pH range (increase the dissociation rate in the acidic pH range) are known. Such methods also include methods for reducing the antigen-binding activity in the acidic pH range (increasing the dissociation rate in the acidic pH range) by introducing amino acid substitutions into the amino acid sequences of wild-type isotypes (amino acid sequences of wild type IgG1, IgG2, IgG3, or IgG4). The sequence of hinge region in the antibody constant region is considerably different among isotypes (IgG1, IgG2, IgG3, and IgG4), and the difference in the hinge region amino acid sequence has a great impact on the antigen-binding activity. Thus, it is possible to select an appropriate isotype to reduce the antigen-binding activity in the acidic pH range (increase the dissociation rate in the acidic pH range) depending on the type of antigen or epitope. Furthermore, since the difference in the hinge region amino acid sequence has a great impact on the antigen-binding activity, preferred amino acid substitution sites in the amino acid sequences of wild type isotypes are presumed to be within the hinge region.
The above-described methods can be used to produce antigen-binding molecules whose antigen-binding activity in the acidic pH range is reduced (weakened) to less than that in the neutral pH range (antigen-binding molecules that bind in a pH-dependent manner) by amino acid substitution or insertion from antigen-binding molecules that do not have such property. Other methods include methods for directly obtaining antigen-binding molecules having the above-described property. For example, antibodies having a desired property of interest may be directly selected by screening using the pH-dependent antigen binding as an indicator from antibodies obtained by immunizing animals (mice, rats, hamsters, rabbits, human immunoglobulin-transgenic mice, human immunoglobulin-transgenic rats, human immunoglobulin-transgenic rabbits, llamas, camels, etc.) with an antigen. Antibodies can be generated by hybridoma technology or B-cell cloning technology (Bernasconi et al, Science (2002) 298, 2199-2202; WO2008/081008) which are methods known to those skilled in the art, but not limited thereto. Alternatively, antibodies that have the property of interest may be directly selected by screening using the pH-dependent antigen binding as an indicator from a library of presenting antigen-binding domain in vitro. Such library includes human naive library, immunized library from non-human animal and human, semi-synthetic library and synthetic library which are libraries known to those skilled in the art (Methods Mol Biol. 2002; 178: 87-100; J Immunol Methods. 2004 June; 289(1-2): 65-80; and Expert Opin Biol Ther. 2007 May; 7(5): 763-79), but not limited thereto. However, the methods are not particularly limited to these examples.
In another preferred embodiment, the antigen-binding molecule of the present invention comprises a calcium-ion dependent antigen-binding domain. The antigen-binding activity of such an antigen-binding molecule depends of the calcium concentration, whereby the antigen-binding activity at a low calcium concentration is lower than that at a high calcium concentration.
Preferably, the antigen-binding activity includes the antigen-binding activity at an ionized calcium concentration of 0.5 to 10 micromolar. More preferable ionized calcium concentrations include the ionized calcium concentration in the early endosome in vivo. Specifically, the antigen-binding activity includes the activity at 1 to 5 micromolar. Meanwhile, the antigen-binding activity of an antigen-binding molecule at a high calcium concentration is not particularly limited, provided that it is the antigen-binding activity at an ionized calcium concentration of 100 micromolar to 10 mM. Preferably, the antigen-binding activity includes the antigen-binding activity at an ionized calcium concentration of 200 micromolar to 5 mM. Preferably, a low calcium concentration is an ionized calcium concentration of 0.1 to 30 micromolar, and a high calcium concentration is an ionized calcium concentration of 100 micromolar to 10 mM.
Preferably, the low calcium concentration is an intraendosomal concentration of ionized calcium, and the high calcium concentration is a plasma concentration of ionized calcium. More specifically, the antigen-binding molecules comprising said calcium-dependent antigen-binding domain include antigen-binding molecules whose antigen-binding activity at the ionized calcium concentration in the early endosome in vivo (a low calcium concentration of such as 1 to 5 micromolar) is lower than that at the ionized calcium concentration in plasma in vivo (a high calcium concentration of such as 0.5 to 2.5 mM).
With respect to the antigen-binding activity of an antigen-binding molecule whose antigen-binding activity at a low calcium concentration is lower than that at a high calcium concentration, there is no limitation on this difference in the antigen-binding activity, provided that the antigen-binding activity at a low calcium concentration is lower than that at a high calcium concentration. It is even acceptable that the antigen-binding activity of an antigen-binding molecule is only slightly lower under a low calcium concentration condition.
In a preferred embodiment, for an antigen-binding molecule of the present invention whose antigen-binding activity at a low calcium concentration (low Ca) is lower than that at a high calcium concentration (high Cal), the value of KD (low Ca)/KD (high Ca), which is the KD ratio between low and high calcium concentration, is 2 or more, preferably the value of KD (low Ca)/KD (high Ca) is 10 or more, and more preferably the value of KD (low Ca)/KD (high Ca) is 40 or more. The upper limit of the KD (low Ca)/KD (high Ca) value is not particularly limited, and may be any value such as 400, 1,000, and 10,000 provided that it can be produced by techniques known to those skilled in the art.
In another preferred embodiment, for an antigen-binding molecule comprising a calcium-dependent antigen-binding domain whose antigen-binding activity at a low calcium concentration is lower than that at a high calcium concentration, the value of kd (low Ca)/kd (high Ca), which is the ratio of kd for an antigen between a low calcium concentration condition and pH 7.4, is 2 or more, preferably the value of kd (low Ca)/kd (high Ca) is 5 or more, more preferably the value of kd (low Ca)/kd (high Ca) is 10 or more, and still more preferably the value of kd (low Ca)/kd (high Ca) is 30 or more. The upper limit of kd (low Ca)/kd (high Ca) value is not particularly limited, and may be any value such as 50, 100, and 200 as long as it can be produced by techniques known to those skilled in the art.
The antigen-binding activity of an antigen-binding molecule can be determined by methods known to those skilled in the art. Appropriate conditions besides ionized calcium concentration can be selected by those skilled in the art. The antigen-binding activity of an antigen-binding molecule can be assessed by using KD (dissociation constant), apparent KD (apparent dissociation constant), dissociation rate kd (dissociation rate), apparent kd (apparent dissociation: apparent dissociation rate), or the like. They can be determined by methods known to those skilled in the art, for example, using Biacore (GE Healthcare), Scatchard plot, FACS, or such.
Antigen-binding molecules to be screened by the screening method of the present invention may be any antigen-binding molecules. It is possible to screen, for example, antigen-binding molecules having a natural sequence or antigen-binding molecules having an amino acid sequence with a substitution. Antigen-binding molecules comprising a calcium-ion dependent antigen-binding domain to be screened by the screening method of the present invention may be prepared by any methods. It is possible to use, for example, preexisting antibodies, preexisting libraries (phage libraries, etc.), and antibodies and libraries prepared from B cells of immunized animals or hybridomas prepared by immunizing animals, antibodies or libraries obtained by introducing amino acids capable of chelating calcium (for example, aspartic acid or glutamic acid) or non-natural amino acid mutations into such antibodies or libraries (libraries with high content of non-natural amino acids or amino acids capable of chelating calcium (for example, aspartic acid or glutamic acid), libraries introduced with non-natural amino acid mutations or mutations with amino acids capable of chelating calcium (for example, aspartic acid or glutamic acid) at specific sites, or such), or the like.
An antigen-binding molecule whose antigen-binding activity under a low calcium concentration condition is lower than that under a high calcium concentration condition can be readily screened, identified and isolated using methods conventional in the art (see e.g. PCT application no. PCT/JP2011/077619. Examples of such screening methods include the step of assaying for an antigen-binding molecule having at least one function selected from:
(i) the function to promote uptake of an antigen into cells;
(ii) the function to bind to an antigen two or more times;
(iii) the function to promote reduction of the plasma antigen concentration; and
(iv) the function of superior plasma retention.
Specifically, the present invention provides methods of screening for an antigen-binding molecule comprising a calcium-ion dependent antigen-binding domain, which comprises the steps of:
(a) determining the antigen-binding activity of an antigen-binding molecule under a low calcium concentration condition;
(b) determining the antigen-binding activity of the antigen-binding molecule under a high calcium concentration condition; and
(c) selecting an antigen-binding molecule whose antigen-binding activity under the low calcium concentration condition is lower than that under the high calcium concentration condition.
A method for producing an antigen-binding molecule with a calcium-ion dependent antigen-binding domain is for example a method comprising the steps of:
(a) determining the antigen-binding activity of an antigen-binding molecule under a low calcium concentration condition;
(b) determining the antigen-binding activity of the antigen-binding molecule under a high calcium concentration condition; and
(c) selecting an antigen-binding molecule whose antigen-binding activity under the low calcium concentration condition is lower than that under the high calcium concentration condition.
Another method of producing an antigen-binding molecule with a calcium-ion dependent antigen-binding domain is the method comprising the steps of:
(a) contacting an antigen with an antigen-binding molecule or a library of antigen-binding molecules under a high calcium concentration condition;
(b) obtaining an antigen-binding molecule that bound to the antigen in step (a);
(c) allowing the antigen-binding molecule obtained in step (b) to stand under a low calcium concentration condition;
(d) obtaining an antigen-binding molecule whose antigen-binding activity in step (c) is lower than the activity for the selection in step (b);
(e) obtaining a gene encoding the antigen-binding molecule obtained in step (d); and
(f) producing the antigen-binding molecule using the gene obtained in step (e).
Steps (a) to (e) may be repeated two or more times. Thus, the present invention provides the methods further comprising the step of repeating steps (a) to (e) two or more times in the above-described methods. The number of repetitions of steps (a) to (e) is not particularly limited; however, the number is generally ten or less.
Antigen-binding molecules that are used in the production methods of the present invention may be prepared by any conventional method. For example, it is possible to use pre-existing antibodies, pre-existing libraries (phage libraries and the like), antibodies and libraries that are prepared from hybridomas obtained by immunizing animals or from B cells of immunized animals, antibodies and libraries prepared by introducing histidine or non-natural amino acid mutations into the above-described antibodies and libraries (libraries with high content of histidine or non-natural amino acid, libraries introduced with histidine or non-natural amino acid at specific sites, and the like), and such.
Further methods to screen such calcium-ion dependent antigen-binding molecules or calcium-ion dependent antigen-binding domains are described in the PCT application no. PCT/JP2011/077619.
Antigens that are recognized by antigen-binding molecules of the present invention, such as the antibodies of the present invention, are not particularly limited. Such antigen-binding molecules of the present invention may recognize any antigen. Specific examples of an antigen that is recognized by the antigen-binding molecule of the present invention include but are not limited to: 17-IA, 4-1 BB, 4Dc, 6-keto-PGF1a, 8-iso-PGF2a, 8-oxo-dG, A1 Adenosine Receptor, A33, ACE, ACE-2, Activin, Activin A, Activin AB, Activin B, Activin C, Activin RIA, Activin RIA ALK-2, Activin RIB ALK-4, Activin RIIA, Activin RIIB, ADAM, ADAM10, ADAM12, ADAM15, ADAM17/TACE, ADAMS, ADAM9, ADAMTS, ADAMTS4, ADAMTS5, Addressins, adiponectin, ADP ribosyl cyclase-1, aFGF, AGE, ALCAM, ALK, ALK-1, ALK-7, allergen, alpha1-antichemotrypsin, alpha1-antitrypsin, alpha-synuclein, alpha-V/beta-1 antagonist, aminin, amylin, amyloid beta, amyloid immunoglobulin heavy chain variable region. amyloid immunoglobulin light chain variable region, Androgen, ANG, angiotensinogen, Angiopoietin ligand-2, anti-Id, antithrombin III, Anthrax, APAF-1, APE, APJ, apo A1, apo serum amyloid A, Apo-SAA, APP, APRIL, AR, ARC, ART, Artemin, ASPARTIC, Atrial natriuretic factor, Atrial natriuretic peptide, atrial natriuretic peptides A, atrial natriuretic peptides B, atrial natriuretic peptides C, av/b3 integrin, Axl, B7-1, B7-2, B7-H, BACE, BACE-1, Bacillus anthracis protective antigen, Bad, BAFF, BAFF-R, Bag-1, BAK, Bax, BCA-1, BCAM, Bcl, BCMA, BDNF, b-ECGF, beta-2-microglobulin, betalactamase, bFGF, BID, Bik, BIM, BLC, BL-CAM, BLK, B-lymphocyte Stimulator (BIyS), BMP, BMP-2 (BMP-2a), BMP-3 (Osteogenin), BMP-4 (BMP-2b), BMP-5, BMP-6 (Vgr-1), BMP-7 (OP-1), BMP-8 (BMP-8a), BMPR, BMPR-IA (ALK-3), BMPR-IB (ALK-6), BMPR-II (BRK-3), BMPs, BOK, Bombesin, Bone-derived neurotrophic factor, bovine growth hormone, BPDE, BPDE-DNA, BRK-2, BTC, B-lymphocyte cell adhesion molecule, C10, C1-inhibitor, C1q, C3, C3a, C4, C5, C5a (complement 5a), CA125, CAD-8, Cadherin-3, Calcitonin, cAMP, Carbonic anhydrase-IX, carcinoembryonic antigen (CEA), carcinoma-associated antigen, Cardiotrophin-1, Cathepsin A, Cathepsin B, Cathepsin C/DPPI, Cathepsin D, Cathepsin E, Cathepsin H, Cathepsin L, Cathepsin O, Cathepsin S, Cathepsin V, Cathepsin X/Z/P, CBL, CCI, CCK2, CCL, CCL1/1-309, CCL11/Eotaxin, CCL12/MCP-5, CCL13/MCP-4, CCL14/HCC-1, CCL15/HCC-2, CCL16/HCC-4, CCL17/TARC, CCL18/PARC, CCL19/ELC, CCL2/MCP-1, CCL20/MIP-3-alpha, CCL21/SLC, CCL22/MDC, CCL23/MPIF-1, CCL24/Eotaxin-2, CCL25/TECK, CCL26/Eotaxin-3, CCL27/CTACK, CCL28/MEC, CCL3/M1P-1-alpha, CCL3L1/LD-78-beta, CCL4/MIP-1-beta, CCL5/RANTES, CCL6/C10, CCL7/MCP-3, CCL8/MCP-2, CCL9/10/MTP-1-gamma, CCR, CCR1, CCR10, CCR2, CCR3, CCR4, CCR5, CCR6, CCR7, CCR8, CCR9, CD1, CD10, CD105, CD11a, CD11b, CD11c, CD123, CD13, CD137, CD138, CD14, CD140a, CD146, CD147, CD148, CD15, CD152, CD16, CD164, CD18, CD19, CD2, CD20, CD21, CD22, CD23, CD25, CD26, CD27L, CD28, CD29, CD3, CD30, CD30L, CD32, CD33 (p67 proteins), CD34, CD37, CD38, CD3E, CD4, CD40, CD40L, CD44, CD45, CD46, CD49a, CD49b, CD5, CD51, CD52, CD54, CD55, CD56, CD6, CD61, CD64, CD66e, CD7, CD70, CD74, CD8, CD80 (B7-1), CD89, CD95, CD105, CD158a, CEA, CEACAM5, CFTR, cGMP, CGRP receptor, CINC, CKb8-1, Claudin 18, CLC, Clostridium botulinum toxin, Clostridium difficile toxin, Clostridium perfringens toxin, c-Met, CMV, CMV UL, CNTF, CNTN-1, complement factor 3 (C3), complement factor D, corticosteroid-binding globulin, Colony stimulating factor-1 receptor, COX, C-Ret, CRG-2, CRTH2, CT-1, CTACK, CTGF, CTLA-4, CX3CL1/Fractalkine, CX3CR1, CXCL, CXCL1/Gro-alpha, CXCL10, CXCL11/1-TAC, CXCL12/SDF-1-alpha/beta, CXCL13/BCA-1, CXCL14/BRAK, CXCL15/Lungkine CXCL16, CXCL16, CXCL2/Gro-beta CXCL3/Gro-gamma, CXCL3, CXCL4/PF4, CXCL5/ENA-78, CXCL6/GCP-2, CXCL7/NAP-2, CXCL8/IL-8, CXCL9/Mig, CXCL10/IP-10, CXCR, CXCR1, CXCR2, CXCR3, CXCR4, CXCR5, CXCR6, cystatin C, cytokeratin tumor-associated antigen, DAN, DCC, DcR3, DC-SIGN, Decay accelerating factor, Delta-like protein ligand 4, des(1-3)-IGF-1 (brain IGF-1), Dhh, DHICA oxidase, Dickkopf-1, digoxin, Dipeptidyl peptidase IV, DK1, DNAM-1, Dnase, Dpp, DPPIV/CD26, Dtk, ECAD, EDA, EDA-A1, EDA-A2, EDAR, EGF, EGFR (ErbB-1), EGF like domain containing protein 7, Elastase, elastin, EMA, EMMPRIN, ENA, ENA-78, Endosialin, endothelin receptor, endotoxin, Enkephalinase, eNOS, Eot, Eotaxin, Eotaxin-2, eotaxini, EpCAM, Ephrin B2/EphB4, Epha2 tyrosine kinase receptor, epidermal growth factor receptor (EGFR), ErbB2 receptor, ErbB3 tyrosine kinase receptor, ERCC, erythropoietin (EPO), Erythropoietin receptor, E-selectin, ET-1, Exodus-2, F protein of RSV, F10, F11, F12, F13, F5, F9, Factor Ia, Factor IX, Factor Xa, Factor VII, factor VIII, Factor VIIIc, Fas, FcalphaR, FcepsilonRI, FcgammaIIb, FcgammaRI, FcgammaRIIa, FcgammaRIIIa, FcgammaRIIIb, FcRn, FEN-1, Ferritin, FGF, FGF-19, FGF-2, FGF-2 receptor, FGF-3, FGF-8, FGF-acidic, FGF-basic, FGFR, FGFR-3, Fibrin, fibroblast activation protein (FAP), fibroblast growth factor, fibroblast growth factor-10, fibronectin, FL, FLIP, Flt-3, FLT3 ligand, Folate receptor, follicle stimulating hormone (FSH), Fractalkine (CX3C), free heavy chain, free light chain, FZD1, FZD10, FZD2, FZD3, FZD4, FZD5, FZD6, FZD7, FZD8, FZD9, G250, Gas 6, GCP-2, GCSF, G-CSF, G-CSF receptor, GD2, GD3, GDF, GDF-1, GDF-15 (MIC-1), GDF-3 (Vgr-2), GDF-5 (BMP-14/CDMP-1), GDF-6 (BMP-13/CDMP-2), GDF-7 (BMP-12/CDMP-3), GDF-8 (Myostatin), GDF-9, GDNF, Gelsolin, GFAP, GF-CSF, GFR-alpha1, GFR-alpha2, GFR-alpha3, GF-beta1, gH envelope glycoprotein, GITR, Glucagon, Glucagon receptor, Glucagon-like peptide 1 receptor, Glut 4, Glutamate carboxypeptidase II, glycoprotein hormone receptors, glycoprotein IIb/IIIa (GP IIb/IIIa), Glypican-3, GM-CSF, GM-CSF receptor, gp130, gp140, gp72, granulocyte-CSF (G-CSF), GRO/MGSA, Growth hormone releasing factor, GRO-beta, GRO-gamma, H. pylori, Hapten (NP-cap or NIP-cap), HB-EGF, HCC, HCC 1, HCMV gB envelope glycoprotein, HCMV UL, Hemopoietic growth factor (HGF), Hep B gp120, heparanase, heparin cofactor II, hepatic growth factor, Bacillus anthracis protective antigen, Hepatitis C virus E2 glycoprotein, Hepatitis E, Hepcidin, Her1, Her2/neu (ErbB-2), Her3 (ErbB-3), Her4 (ErbB-4), herpes simplex virus (HSV) gB glycoprotein, HGF, HGFA, High molecular weight melanoma-associated antigen (HMW-MAA), HIV envelope proteins such as GP120, HIV MIB gp120 V3 loop, HLA, HLA-DR, HM1.24, HMFG PEM, HMGB-1, HRG, Hrk, HSP47, Hsp90, HSV gD glycoprotein, human cardiac myosin, human cytomegalovirus (HCMV), human growth hormone (hGH), human serum albumin, human tissue-type plasminogen activator (t-PA), Huntingtin, HVEM, IAP, ICAM, ICAM-1, ICAM-3, ICE, ICOS, IFN-alpha, IFN-beta, IFN-gamma, IgA, IgA receptor, IgE, IGF, IGF binding proteins, IGF-1, IGF-1R, IGF-2, IGFBP, IGFR, IL, IL-1, IL-10, IL-10 receptors, IL-11, IL-11 receptors, IL-12, IL-12 receptors, IL-13, IL-13 receptors, IL-15, IL-15 receptors, IL-16, IL-16 receptors, IL-17, IL-17 receptors, IL-18 (IGIF), IL-18 receptors, IL-1alpha, IL-1beta, IL-1 receptors, IL-2, IL-2 receptors, IL-20, IL-20 receptors, IL-21, IL-21 receptors, IL-23, IL-23 receptors, IL-2 receptors, IL-3, IL-3 receptors, IL-31, IL-31 receptors, IL-3 receptors, IL-4, IL-4 receptors IL-5, IL-5 receptors, IL-6, IL-6 receptors, IL-7, IL-7 receptors, IL-8, IL-8 receptors, IL-9, IL-9 receptors, immunoglobulin immune complex, immunoglobulins, INF-alpha, INF-alpha receptors, INF-beta, INF-beta receptors, INF-gamma, INF-gamma receptors, IFN type-I, IFN type-I receptor, influenza, inhibin, Inhibin alpha, Inhibin beta, iNOS, insulin, Insulin A-chain, Insulin B-chain, Insulin-like growth factor 1, insulin-like growth factor 2, insulin-like growth factor binding proteins, integrin, integrin alpha2, integrin alpha3, integrin alpha4, integrin alpha4/beta1, integrin alpha-V/beta-3, integrin alpha-V/beta-6, integrin alpha4/beta7, integrin alpha5/beta1, integrin alpha5/beta3, integrin alpha5/beta6, integrin alpha-delta (alphaV), integrin alpha-theta, integrin beta1, integrin beta2, integrin beta3(GPIIb-IIIa), IP-10, I-TAC, JE, kalliklein, Kallikrein 11, Kallikrein 12, Kallikrein 14, Kallikrein 15, Kallikrein 2, Kallikrein 5, Kallikrein 6, Kallikrein L1, Kallikrein L2, Kallikrein L3, Kallikrein L4, kallistatin, KC, KDR, Keratinocyte Growth Factor (KGF), Keratinocyte Growth Factor-2 (KGF-2), KGF, killer immunoglobulin-like receptor, kit ligand (KL), Kit tyrosine kinase, laminin 5, LAMP, LAPP (Amylin, islet-amyloid polypeptide), LAP (TGF-1), latency associated peptide, Latent TGF-1, Latent TGF-1 bp1, LBP, LDGF, LDL, LDL receptor, LECT2, Lefty, Leptin, leutinizing hormone (LH), Lewis-Y antigen, Lewis-Y related antigen, LFA-1, LFA-3, LFA-3 receptors, Lfo, LIF, LIGHT, lipoproteins, LIX, LKN, Lptn, L-Selectin, LT-a, LT-b, LTB4, LTBP-1, Lung surfactant, Luteinizing hormone, Lymphotactin, Lymphotoxin Beta Receptor, Lysosphingolipid receptor, Mac-1, macrophage-CSF (M-CSF), MAdCAM, MAG, MAP2, MARC, maspin, MCAM, MCK-2, MCP, MCP-1, MCP-2, MCP-3, MCP-4, MCP-I (MCAF), M-CSF, MDC, MDC (67 a.a.), MDC (69 a.a.), megsin, Mer, MET tyrosine kinase receptor family, METALLOPROTEASES, Membrane glycoprotein OX2, Mesothelin, MGDF receptor, MGMT, MHC(HLA-DR), microbial protein, MIF, MIG, MIP, MIP-1 alpha, MIP-1 beta, MIP-3 alpha, MIP-3 beta, MIP-4, MK, MMAC1, MMP, MMP-1, MMP-10, MMP-11, MMP-12, MMP-13, MMP-14, MMP-15, MMP-2, MMP-24, MMP-3, MMP-7, MMP-8, MMP-9, monocyte attractant protein, monocyte colony inhibitory factor, mouse gonadotropin-associated peptide, MPIF, Mpo, MSK, MSP, MUC-16, MUC18, mucin (Mud), Muellerian-inhibiting substance, Mug, MuSK, Myelin associated glycoprotein, myeloid progenitor inhibitor factor-1 (MPIF-I), NAIP, Nanobody, NAP, NAP-2, NCA 90, NCAD, N-Cadherin, NCAM, Neprilysin, Neural cell adhesion molecule, neroserpin, Neuronal growth factor (NGF), Neurotrophin-3, Neurotrophin-4, Neurotrophin-6, Neuropilin 1, Neurturin, NGF-beta, NGFR, NKG20, N-methionyl human growth hormone, nNOS, NO, Nogo-A, Nogo receptor, non-structural protein type 3 (NS3) from the hepatitis C virus, NOS, Npn, NRG-3, NT, NT-3, NT-4, NTN, OB, OGG1, Oncostatin M, OP-2, OPG, OPN, OSM, OSM receptors, osteoinductive factors, osteopontin, OX40L, OX40R, oxidized LDL, p150, p95, PADPr, parathyroid hormone, PARC, PARP, PBR, PBSF, PCAD, P-Cadherin, PCNA, PCSK9, PDGF, PDGF receptor, PDGF-AA, PDGF-AB, PDGF-BB, PDGF-D, PDK-1, PECAM, PEDF, PEM, PF-4, PGE, PGF, PGI2, PGD2, PIGF, PIN, PLA2, Placenta growth factor, placental alkaline phosphatase (PLAP), placental lactogen, plasminogen activator inhibitor-1, platelet-growth factor, plgR, PLP, poly glycol chains of different size (e.g. PEG-20, PEG-30, PEG40), PP14, prekallikrein, prion protein, procalcitonin, Programmed cell death protein 1, proinsulin, prolactin, Proprotein convertase PC9, prorelaxin, prostate specific membrane antigen (PSMA), Protein A, Protein C, Protein D, Protein S, Protein Z, PS, PSA, PSCA, PsmAr, PTEN, PTHrp, Ptk, PTN, P-selectin glycoprotein ligand-1, R51, RAGE, RANK, RANKL, RANTES, relaxin, Relaxin A-chain, Relaxin B-chain, renin, respiratory syncytial virus (RSV) F, Ret, reticulon 4, Rheumatoid factors, RLI P76, RPA2, RPK-1, RSK, RSV Fgp, S100, RON-8, SCF/KL, SCGF, Sclerostin, SDF-1, SDF1 alpha, SDF1 beta, SERINE, Serum Amyloid P, Serum albumin, sFRP-3, Shh, Shiga like toxin II, SIGIRR, SK-1, SLAM, SLPI, SMAC, SMDF, SMOH, SOD, SPARC, sphingosine 1-phosphate receptor 1, Staphylococcal lipoteichoic acid, Stat, STEAP, STEAP-II, stem cell factor (SCF), streptokinase, superoxide dismutase, syndecan-1, TACE, TACI, TAG-72 (tumor-associated glycoprotein-72), TARC, TB, TCA-3, T-cell receptor alpha/beta, TdT, TECK, TEM1, TEM5, TEM7, TEM8, Tenascin, TERT, testicular PLAP-like alkaline phosphatase, TfR, TGF, TGF-alpha, TGF-beta, TGF-beta Pan Specific, TGF-beta RII, TGF-beta RIIb, TGF-beta RIII, TGF-beta R1 (ALK-5), TGF-beta1, TGF-beta2, TGF-beta3, TGF-beta4, TGF-beta5, TGF-I, Thrombin, thrombopoietin (TPO), Thymic stromal lymphoprotein receptor, Thymus Ck-1, thyroid stimulating hormone (TSH), thyroxine, thyroxine-binding globulin, Tie, TIMP, TIQ, Tissue Factor, tissue factor protease inhibitor, tissue factor protein, TMEFF2, Tmpo, TMPRSS2, TNF receptor I, TNF receptor II, TNF-alpha, TNF-beta, TNF-beta2, TNFc, TNF-RI, TNF-RII, TNFRSF10A (TRAIL R1Apo-2/DR4), TNFRSF10B (TRAIL R2 DR5/KILLER/TRICK-2A/TRICK-B), TNFRSF10C (TRAIL R3DcR1/LIT/TRID), TNFRSF10D (TRAIL R4DcR2/TRUNDD), TNFRSF11A (RANK ODF R/TRANCE R), TNFRSF11B (OPG OCIF/TR1), TNFRSF12 (TWEAK R FN14), TNFRSF12A, TNFRSF13B (TAL1), TNFRSF13C (BAFF R), TNFRSF14 (HVEM ATAR/HveA/LIGHT R/TR2), TNFRSF16 (NGFR p75NTR), TNFRSF17 (BCMA), TNFRSF18 (GITR AITR), TNFRSF19 (TROY TAJ/TRADE), TNFRSF19L (RELT), TNFRSF1A (TNF R1CD120a/p55-60), TNFRSF1B (TNF RIICD120b/p75-80), TNFRSF21 (DR6), TNFRSF22 (DcTRAIL R2TNFRH2), TNFRSF25 (DR3Apo-3/LARD/TR-3/TRAMP/WSL-1), TNFRSF26 (TNFRH3), TNFRSF3 (LTbR TNF RIII/TNFC R), TNFRSF4 (OX40 ACT35/TXGP1R), TNFRSF5 (CD40 p50), TNFRSF6 (Fas Apo-1/APT1/CD95), TNFRSF6B (DcR3M68/TR6), TNFRSF7 (CD27), TNFRSF8 (CD30), TNFRSF9 (4-1 BB CD137/ILA), TNFRST23 (DcTRAIL R1 TNFRH1), TNFSF10 (TRAIL Apo-2 Ligand/TL2), TNFSF11 (TRANCE/RANK Ligand ODF/OPG Ligand), TNFSF12 (TWEAK Apo-3 Ligand/DR3Ligand), TNFSF13 (APRIL TALL2), TNFSF13B (BAFF BLYS/TALL1/THANK/TNFSF20), TNFSF14 (LIGHT HVEM Ligand/LTg), TNFSF15 (TL1A/VEGI), TNFSF18 (GITR Ligand AITR Ligand/TL6), TNFSF1A (TNF-a Conectin/DIF/TNFSF2), TNFSF1B (TNF-b LTa/TNFSF1), TNFSF3 (LTb TNFC/p33), TNFSF4 (OX40 Ligand gp34/TXGP1), TNFSF5 (CD40 Ligand CD154/gp39/HIGM1/IMD3/TRAP), TNFSF6 (Fas Ligand Apo-1 Ligand/APT1 Ligand), TNFSF7 (CD27 Ligand CD70), TNFSF8 (CD30 Ligand CD153), TNFSF9 (4-1 BB Ligand CD137 Ligand), TNF-alpha, TNF-beta, TNIL-1, toxic metabolite, TP-1, t-PA, Tpo, TRAIL, TRAIL R, TRAIL-R1, TRAIL-R2, TRANCE, transferrin receptor, transforming growth factors (TGF) such as TGF-alpha and TGF-beta, Transmembrane glycoprotein NMB, Transthyretin, TRF, Trk, TROP-2, Trophoblast glycoprotein, TSG, TSLP, Tumor Necrosis Factor (TNF), tumor-associated antigen CA 125, tumor-associated antigen expressing Lewis Y related carbohydrate, TWEAK, TXB2, Ung, uPAR, uPAR-1, Urokinase, VAP-1, vascular endothelial growth factor (VEGF), vaspin, VCAM, VCAM-1, VECAD, VE-Cadherin, VE-Cadherin-2, VEFGR-1 (flt-1), VEFGR-2, VEGF receptor (VEGFR), VEGFR-3 (flt-4), VEGI, VIM, Viral antigens, VitB12 receptor, Vitronectin receptor, VLA, VLA-1, VLA-4, VNR integrin, von Willebrand Factor (vWF), WIF-1, WNT1, WNT10A, WNT10B, WNT11, WNT16, WNT2, WNT2B/13, WNT3, WNT3A, WNT4, WNT5A, WNT5B, WNT6, WNT7A, WNT7B, WNT8A, WNT8B, WNT9A, WNT9B, XCL1, XCL2/SCM-1-beta, XCL1/Lymphotactin, XCR1, XEDAR, XIAP, XPD, HMGB1, IgA, Aa, CD81, CD97, CD98, DDR1, DKK1, EREG, Hsp90, IL-17/IL-17R, IL-20/IL-20R, oxidized LDL, PCSK9, prekallikrein, RON, TMEM16F, SOD1, Chromogranin A, Chromogranin B, tau, VAP1, High molecular weight kininogen, IL-31, IL-31R, Nav1.1, Nav1.2, Nav1.3, Nav1.4, Nav1.5, Nav1.6, Nav1.7, Nav1.8, Nav1.9, EPCR, C1, C1q, C1r, C1s, C2, C2a, C2b, C3, C3a, C3b, C4, C4a, C4b, C5, C5a, C5b, C6, C7, C8, C9, factor B, factor D, factor H, properdin, sclerostin, fibrinogen, fibrin, prothrombin, thrombin, tissue factor, factor V, factor Va, factor VII, factor VIIa, factor VIII, factor VIIIa, factor IX, factor IXa, factor X, factor Xa, factor XI, factor XIa, factor XII, factor XIIa, factor XIII, factor XIIIa, TFPI, antithrombin III, EPCR, thrombomodulin, TAPI, tPA, plasminogen, plasmin, PAI-1, PAI-2, GPC3, Syndecan-1, Syndecan-2, Syndecan-3, Syndecan-4, LPA, SIP.
Antigen binding molecules described in present invention are capable of reducing total antigen concentration of the above-described antigens in plasma. Antigen binding molecules described in present invention are also capable of eliminating virus, bacteria, and fungus from plasma by binding to structural components of virus, bacteria and fungus. Particularly, F protein of RSV, Staphylococcal lipoteichoic acid, Clostridium difficile toxin, Shiga like toxin II, Bacillus anthracis protective antigen and Hepatitis C virus E2 glycoprotein can be used as a structural components of virus, bacteria and fungus.
The present invention also provides many uses of the antigen-binding molecules of the present invention as described above.
Thus, the present invention provides the use of the modified antigen-binding molecules of the present invention for improving the antigen-binding molecule-mediated antigen uptake into cells. Furthermore, the present invention also provides methods for improving antigen-binding molecule-mediated antigen uptake into cells comprising altering an antigen-binding molecule comprising a parent FcRn-binding domain, by substituting an amino acid in the parent FcRn-binding domain at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436 and thereby increasing the FcRn-binding activity at neutral pH as compared to an antigen-binding molecule having an intact FcRn-binding domain.
Herein, the term “antigen uptake into cells” mediated by an antigen-binding molecule means that antigens are taken up into cells by endocytosis. Meanwhile, herein, the term “facilitate the uptake into cells” means that the rate of intracellular uptake of antigen-binding molecule bound to an antigen in plasma is enhanced, and/or the quantity of recycling of uptaken antigen to the plasma is reduced. This means that the rate of uptake into cells is facilitated as compared to the antigen-binding molecule before the modification of the FcRn-binding domain and thus before increasing the human FcRn-binding activity of the antigen-binding molecule in the neutral pH range, or before increasing the human FcRn-binding activity and reducing the antigen-binding activity (binding ability) of the antigen-binding molecule in the acidic pH range to less than its antigen-binding activity in the neutral pH range. The rate is improved preferably as compared to intact IgG, and more preferably as compared to intact human IgG. Thus, in the present invention, whether antigen uptake into cells is facilitated by an antigen-binding molecule can be assessed based on an increase in the rate of antigen uptake into cells. The rate of antigen uptake into cells can be calculated, for example, by monitoring over time reduction in the antigen concentration in the culture medium containing human FcRn-expressing cells after adding the antigen and antigen-binding molecule to the medium, or monitoring over time the amount of antigen uptake into human FcRn-expressing cells. Using methods of the present invention for facilitating the rate of antigen-binding molecule-mediated antigen uptake into cells, for example, the rate of antigen elimination from the plasma can be enhanced by administering antigen-binding molecules of the present invention. Thus, whether antigen-binding molecule-mediated antigen uptake into cells is facilitated can also be assessed, for example, by testing whether the rate of antigen elimination from the plasma is accelerated or whether the total antigen concentration in plasma is reduced by administering an antigen-binding molecule of the present invention.
Herein, the term “total antigen concentration in plasma” means the sum of antigen-binding molecule bound antigen and non-bound antigen concentration, or “free antigen concentration in plasma” which is antigen-binding molecule non-bound antigen concentration. Various methods to measure “total antigen concentration in plasma” and “free antigen concentration in plasma” are well known in the art as described hereinafter.
The present invention also provides use of the antigen-binding molecule of the present invention for increasing the total number of antigens to which a single antigen-binding molecule can bind before its degradation. The present invention also provides methods for increasing the number of antigens to which a single antigen-binding molecule can bind, by using an antigen-binding molecule of the present invention. Specifically, the present invention provides methods for increasing the total number of antigens to which a single antigen-binding molecule can bind, by substituting an amino acid in the parent FcRn-binding domain of said antigen-binding molecule at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436 and thereby increasing the FcRn-binding activity at neutral pH as compared to an antigen-binding molecule having an intact FcRn-binding domain.
A “conventional antibody” can usually bind only one or two antigens before it is degraded in the endosome. An antigen-binding molecule of the present invention can increase the number of cycles achieved until the antigen-binding molecule is degraded, whereby each cycle consists of: binding of an antigen to the antigen-binding molecule in plasma, intracellular uptake of the antigen-binding molecule bound to the antigen, and dissociation from the antigen in the endosome, followed by return of the antigen-binding molecule to the plasma. This means that the number of cycles is increased as compared to the antigen-binding molecule before the modification of the FcRn-binding domain and thus before increasing the human FcRn-binding activity of the antigen-binding molecule in the neutral pH or acidic range, or before increasing the human FcRn-binding activity and reducing the antigen-binding activity (binding ability) of the antigen-binding molecule in the acidic pH range to less than its antigen-binding activity in the neutral pH range. Thus, whether the number of cycles is increased can be assessed by testing whether the above-described “intracellular uptake is facilitated” or whether the “pharmacokinetics is improved” as described below.
The present invention also provides for the use of the antigen-binding molecules of the present invention for improving the antigen-removal from the blood in mammals, i.e. in humans. In particular, the present invention provides the use of the antigen-binding molecule of the present invention for reducing the plasma concentration of a specific antigen, wherein the antigen-binding molecule comprises an antigen-binding domain which can bind said antigen. The present invention also provides a method for reducing the plasma concentration of a specific antigen, wherein the antigen-binding molecule comprises an antigen-binding domain which can bind said antigen, by substituting an amino acid in a parent FcRn-binding domain at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436 and thereby increasing the FcRn-binding activity at neutral pH as compared to an antigen-binding molecule having an intact FcRn-binding domain.
The present invention also provides the use of the antigen-binding molecules of the present invention for facilitating the extracellular release of antigen-free antigen-binding molecule taken up into cells in an antigen-bound form. More specifically, the present invention provides methods for facilitating the extracellular release of antigen-free antigen-binding molecule taken up into cells in an antigen-bound form without significantly increasing the binding activity for a pre-existing ADA at neutral pH compared to parent antibody, by substituting an amino acid in the parent FcRn-binding domain at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436 and thereby increasing the FcRn-binding activity at neutral pH as compared to an antigen-binding molecule having an intact FcRn-binding domain
Herein, the “extracellular release of antigen-free antigen-binding molecule taken up into cells in an antigen-bound form” does not necessarily mean that all of the antigen-binding molecules bound to antigen taken up into cells are released in an antigen-free form outside of the cell. It is acceptable that the proportion of antigen-binding molecules released in an antigen-free form to the outside of the cell is increased as compared to before the modification of the FcRn-binding domain and thus before reducing the antigen-binding activity of the antigen-binding molecule in the acidic pH range to less than that in the neutral pH range and increasing the human FcRn-binding activity in the neutral pH range. The antigen-binding molecule released to the outside of the cell preferably retains the antigen-binding activity.
The present invention also provides the use of an FcRn-binding domain of the present invention for increasing the ability of the antigen-binding molecule to eliminate plasma antigen. In the present invention, “methods for increasing the ability to eliminate plasma antigen” is synonymous to “methods for augmenting the ability of an antigen-binding molecule to eliminate antigen from plasma”. More specifically, the present invention provides methods for increasing the ability of an antigen-binding molecule to eliminate plasma antigen by substituting an amino acid in the parent FcRn-binding domain at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436 and thereby increasing the FcRn-binding activity at neutral and/or acidic pH as compared to an antigen-binding molecule having an intact FcRn-binding domain.
Herein, the term “ability to eliminate plasma antigen” means the ability to remove antigen from the plasma when antigen-binding molecules are administered or secreted in vivo. Thus, “increase in the ability of antigen-binding molecule to eliminate plasma antigen” herein means that the rate of antigen elimination from the plasma is accelerated upon administration of the antigen-binding molecule as compared to before the modification of the FcRn-binding domain and thus before increasing the human FcRn-binding activity of the antigen-binding molecule in the neutral pH range or before increasing the human FcRn-binding activity and simultaneously reducing its antigen-binding activity in the acidic pH range to less than that in the neutral pH range. The increase in the activity of an antigen-binding molecule to eliminate antigen from the plasma can be assessed, for example, by administering a soluble antigen and an antigen-binding molecule in vivo, and measuring the concentration of the soluble antigen in plasma after administration. When the concentration of soluble antigen in plasma after administration of the soluble antigen and modified antigen-binding molecule is reduced, the ability of antigen-binding molecule to eliminate plasma antigen can be judged to be increased. A form of soluble antigen can be antigen-binding molecule bound antigen or antigen-binding molecule non-bound antigen whose concentration can be determined as “antigen-binding molecule bound antigen concentration in plasma” and “antigen-binding molecule non-bound antigen concentration in plasma” respectively. The latter is synonymous to “free antigen concentration in plasma”. Since “total antigen concentration in plasma” means the sum of antigen-binding molecule bound antigen and non-bound antigen concentration, or “free antigen concentration in plasma” which is antigen-binding molecule non-bound antigen concentration, the concentration of soluble antigen can be determined as “total antigen concentration in plasma”. Various methods for measuring “total antigen concentration in plasma” or “free antigen concentration in plasma” are well known in the art as described hereinafter.
The present invention also provides the use of the FcRn-binding domain of the present invention for improving the pharmacokinetics of antigen-binding molecules. More specifically, the present invention provides methods for improving the pharmacokinetics of the antigen-binding molecule by substituting an amino acid in the parent FcRn-binding domain at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436 and thereby increasing the FcRn-binding activity at neutral and/or acidic pH as compared to an antigen-binding molecule having an intact FcRn-binding domain.
Herein, the terms “enhancement of pharmacokinetics”, “improvement of pharmacokinetics”, and “superior pharmacokinetics” can be restated as “enhancement of plasma (blood) retention”, “improvement of plasma (blood) retention”, “superior plasma (blood) retention”, and “prolonged plasma (blood) retention”. These terms are used herein as synonyms.
Improving the pharmacokinetics particularly encompasses:
(1) a delayed elimination: prolonging the time between administration and elimination of the antigen-binding molecules from plasma as compared to a Control Antigen-binding Molecule (e.g. antigen-binding molecules having an intact FcRn-binding domain); and/or
(2) prolonging the plasma retention time of the antigen-binding molecules, preferably in a form in which the antibody or antibody derivative can bind to its antigen after administration of the Antigen-binding molecules as compared to the plasma retention time of a Control Antigen-binding Molecule (e.g. antigen-binding molecules having an intact FcRn-binding domain); and/or
(3) shortening the period during which the antigen is free (not bound to an antigen-binding molecule in the body) between administration and elimination of the antigen-binding molecules as compared to a Control Antigen-binding Molecule (prolonging of the period between administration and elimination during which the antigen-binding molecules is bound to its antigen in the body of a subject as compared to a control antigen-binding molecules (e.g. antigen-binding molecules having an intact FcRn-binding domain); and/or
(4) increasing the ratio of antigen bound to an antigen-binding molecules vs. total antigen in the body as compared to the ratio of antigen bound to a Control Antigen-binding Molecule (e.g. antigen-binding molecules having an intact FcRn-binding domain) before degradation of the antibody (increasing the number of binding events of the antigen-binding molecules with its antigen between administration and degradation of the antibody or antibody derivative as compared to the number of binding events of a control antigen-binding molecules between administration and degradation).
(5) reducing plasma total or free antigen concentration after the administration of the antigen-binding molecules compared to the plasma total or free antigen concentration after the administration of a Control Antigen-binding Molecule (e.g. antigen-binding molecules having an intact FcRn-binding domain).
The present invention also provides a method for delaying the elimination of an antigen-binding molecule in a subject, comprising the step of introducing a modification into a FcRn-binding domain of said antigen-binding molecule at one or more of the positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436.
The term “improvement of pharmacokinetics” as used herein refers not only to prolongation of the period between administration of the antigen-binding molecule to a subject (humans, or non-human animals such as mice, rats, monkeys, rabbits, and dogs) and elimination from the plasma (for example, until the antigen-binding molecule is degraded intracellularly or the like and cannot return to the plasma) to, but also to the prolongation of the plasma retention of the antigen-binding molecule in a form that allows antigen binding (for example, in an antigen-free form of the antigen-binding molecule) during the period from administration until degradation of the antigen-binding molecule.
Therefore, the present invention also provides a method of prolonging the plasma retention time of an antigen-binding molecule, comprising the step of introducing a modification into a FcRn-binding domain of said antigen-binding molecule at one or more of the positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436. Intact human IgG can bind to FcRn from non-human animals. For example, administration to mice is preferably used to confirm the property of the antigen-binding molecule of the invention since intact human IgG can bind to mouse FcRn stronger than to human FcRn (Int Immunol. 2001 December; 13(12): 1551-9). As another example, mouse in which its native FcRn genes are disrupted and a transgene for human FcRn gene is harbored to be expressed (Methods Mol Biol. 2010; 602: 93-104) can also be preferably used to be administered in order to confirm the property of the antigen-binding molecule of the invention described hereinafter. Specifically, “improvement of pharmacokinetics” also includes prolongation of the period between administration and degradation of the antigen-binding molecule during which it is not bound to an antigen (the antigen-free form of antigen-binding molecule). The antigen-binding molecule in plasma cannot bind to a new antigen when the antigen-binding molecule has already bound to an antigen. Thus, the longer the period during which the antigen-binding molecule is not bound to an antigen, the longer is the period during which it has the potential to bind to a new antigen (the higher the chance of binding to another antigen). In other words, more antigens are bound during a shorter period of time. Therefore, the plasma concentration of the antigen-free form of antigen-binding molecule can be increased and the total period during which antigen is bound to the antigen-binding molecule can be prolonged by accelerating the antigen elimination from the plasma by administration of the modified antigen-binding molecule.
Specifically, herein “improvement of the pharmacokinetics of antigen-binding molecule” includes the improvement of a pharmacokinetic parameter of the antigen-free form of the antigen-binding molecule (any of prolongation of the half-life in plasma, prolongation of mean retention time in plasma, and impairment of plasma clearance), prolongation of the period during which the antigen is bound to the antigen-binding molecule after administration of the modified antigen-binding molecule, and acceleration of antigen-binding molecule-mediated antigen elimination from the plasma.
The improvement of pharmacokinetics of antigen-binding molecule can be assessed by determining any one of the parameters, half-life in plasma, mean plasma retention time, and plasma clearance for the antigen-binding molecule or the antigen-free form thereof (“Pharmacokinetics: Enshu ni yoru Rikai (Understanding through practice)” Nanzando). For example, the plasma concentration of the antigen-binding molecule or antigen-free form thereof is determined after administration of the antigen-binding molecule to mice, rats, monkeys, rabbits, dogs, or humans. Then, each parameter is determined. When the plasma half-life or mean plasma retention time is prolonged, the pharmacokinetics of the antigen-binding molecule can be judged to be improved. The parameters can be determined by methods known to those skilled in the art. The parameters can be appropriately assessed, for example, by non-compartmental analysis using the pharmacokinetics analysis software WinNonlin (Pharsight) according to the appended instruction manual. The plasma concentration of antigen-free antigen-binding molecule can be determined by methods known to those skilled in the art, for example, using the assay method described in Clin Pharmacol. 2008 April; 48(4): 406-17.
Herein, the term “improvement of pharmacokinetics” also includes prolongation of the period that an antigen is bound to an antigen-binding molecule after administration of the antigen-binding molecule. Whether the period that antigen is bound to the antigen-binding molecule after administration of the antigen-binding molecule is prolonged can be assessed by determining the plasma concentration of free antigen. The prolongation can be judged based on the determined plasma concentration of free antigen or the time period required for an increase in the ratio of free antigen concentration to the total antigen concentration.
The present invention also provides the use of the antigen-binding molecules of the present invention for reducing total or free antigen plasma concentration of a specific antigen, wherein the antigen-binding molecule comprises an antigen-binding domain which can bind said antigen. More specifically, the present invention provides methods for reducing total or free antigen plasma concentration, said method comprising the steps of:
a) providing an antigen-binding molecule comprising a parent FcRn-binding domain, wherein the antigen-binding molecule comprises an antigen-binding domain which can bind said antigen,
b) substituting an amino acid in the parent FcRn-binding domain at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436 and thereby increasing the FcRn-binding activity at neutral pH as compared to an antigen-binding molecule having an intact FcRn-binding domain.
Moreover, the present invention provides, comprising the step of introducing a modification into an FcRn-binding domain of said antigen-binding molecule at one or more of the positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436. The term “antigen-elimination rate” as used herein refers to the number of antigens that an antigen-binding molecule can remove from the plasma in the time between administration and elimination (i.e. degradation) of the antibody or antibody derivative.
The plasma concentration of free antigen not bound to the antigen-binding molecule or the ratio of free antigen concentration to the total concentration can be determined by methods known to those skilled in the art, for example, by the method described in Pharm Res. 2006 January; 23 (1): 95-103. Alternatively, when an antigen exhibits a particular function in vivo, whether the antigen is bound to an antigen-binding molecule that neutralizes the antigen function (antagonistic molecule) can be assessed by testing whether the antigen function is neutralized. Whether the antigen function is neutralized can be assessed by assaying an in vivo marker that reflects the antigen function. Whether the antigen is bound to an antigen-binding molecule that activates the antigen function (agonistic molecule) can be assessed by assaying an in vivo marker that reflects the antigen function.
Determination of the plasma concentration of free antigen and ratio of the amount of free antigen in plasma to the amount of total antigen in plasma, in vivo marker assay, and such measurements are not particularly limited; however, the assays are preferably carried out after a certain period of time has passed after administration of the antigen-binding molecule. In the present invention, the period after administration of the antigen-binding molecule is not particularly limited; those skilled in the art can determine the appropriate period depending on the properties and the like of the administered antigen-binding molecule. Such periods include, for example, one day after administration of the antigen-binding molecule, three days after administration of the antigen-binding molecule, seven days after administration of the antigen-binding molecule, 14 days after administration of the antigen-binding molecule, and 28 days after administration of the antigen-binding molecule. Herein, the term “plasma antigen concentration” means either “total antigen concentration in plasma” which is the sum of antigen-binding molecule bound antigen and non-bound antigen concentration or “free antigen concentration in plasma” which is antigen-binding molecule non-bound antigen concentration.
Total antigen concentration in plasma can be lowered by administration of antigen-binding molecule of the present invention by 2-fold, 5-fold, 10-fold, 20-fold, 50-fold, 100-fold, 200-fold, 500-fold, 1,000-fold, or even higher compared to the administration of a reference antigen-binding molecule comprising the intact human IgG Fc region as a human FcRn-binding domain or compared to when antigen-binding domain molecule of the present invention is not administered.
Molar antigen/antigen-binding molecule ratio can be calculated as shown below;
value A: Molar antigen concentration at each time point
value B: Molar antigen-binding molecule concentration at each time point
value C: Molar antigen concentration per molar antigen-binding molecule concentration (molar antigen/antigen-binding molecule ratio) at each time point
C=A/B.
Smaller value C indicates higher efficiency of antigen elimination per antigen-binding molecule whereas higher value C indicates lower efficiency of antigen elimination per antigen-binding molecule.
Molar antigen/antigen-binding molecule ratio can be lowered by administration of antigen-binding molecule of present invention by 2-fold, 5-fold, 10-fold, 20-fold, 50-fold, 100-fold, 200-fold, 500-fold, 1,000-fold, or even higher as compared to the administration of a reference antigen-binding molecule comprising the intact human IgG Fc region as a human FcRn-binding domain.
Herein, an intact human IgG1, IgG2, IgG3 or IgG4 is preferably used as the intact human IgG for a purpose of a reference intact human IgG to be compared with the antigen-binding molecules for their human FcRn binding activity or in vivo activity. Preferably, a reference antigen-binding molecule comprising the same antigen-binding domain as an antigen-binding molecule of the interest and intact human IgG Fc region as a human FcRn-binding domain can be appropriately used. More preferably, an intact human IgG1 is used for a purpose of a reference intact human IgG to be compared with the antigen-binding molecules for their human FcRn binding activity or in vivo activity.
Reduction of total antigen concentration in plasma or molar antigen/antibody ratio can be assessed as described in Examples 6, 8, and 13 of WO2011/122011. More specifically, using human FcRn transgenic mouse line 32 or line 276 (Jackson Laboratories, Methods Mol Biol. (2010) 602: 93-104.), they can be assessed by either antigen-antibody co-injection model or steady-state antigen infusion model when the antigen-binding molecule of interest does not cross-react with the mouse counterpart antigen. When antigen-binding molecule cross-react with mouse counterpart, they can be assessed by simply injecting antigen-binding molecule to human FcRn transgenic mouse line 32 or line 276 (Jackson Laboratories). In the co-injection model, a mixture of antigen-binding molecule and antigen is administered to the mouse. In the steady-state antigen infusion model, an infusion pump containing an antigen solution is implanted to the mouse to achieve a constant plasma antigen concentration, and then the antigen-binding molecule is injected to the mouse. The same dosage is used for all administered test antigen-binding molecules. Total antigen concentration in plasma, free antigen concentration in plasma and plasma antigen-binding molecule concentration is measured at an appropriate time point using methods known to those skilled in the art.
Total or free antigen concentration in plasma and molar antigen/antigen-binding molecule ratio can be measured at 2, 4, 7, 14, 28, 56, or 84 days after administration to evaluate the long-term effect of the present invention. In other words, a long term plasma antigen concentration is determined by measuring total or free antigen concentration in plasma and molar antigen/antigen-binding molecule ratio at 2, 4, 7, 14, 28, 56, or 84 days after administration of an antigen-binding molecule in order to evaluate the property of the antigen-binding molecule of the present invention. Whether the reduction of plasma antigen concentration or molar antigen/antigen-binding molecule ratio is achieved by antigen-binding molecule described in the present invention can be determined by the evaluation of the reduction at any one or more of the time points described above.
Total or free antigen concentration in plasma and molar antigen/antigen-binding molecule ratio can be measured at 15 min, 1, 2, 4, 8, 12, or 24 hours after administration to evaluate the short-term effect of the present invention. In other words, a short term plasma antigen concentration is determined by measuring total or free antigen concentration in plasma and molar antigen/antigen-binding molecule ratio at 15 min, 1, 2, 4, 8, 12, or 24 hours after administration of an antigen-binding molecule in order to evaluate the property of the antigen-binding molecule of the present invention.
More specifically, those antigen-binding molecules having a long term effect on activity for eliminating antigen in plasma as described in the present invention have human FcRn-binding activity at pH 7.0 and 25 degrees C. within a range of 28-fold to 440-fold stronger than intact human IgG1or KD within a range of 3.0 micromolar to 0.2 micromolar. Preferably, the KD is within a range of 700 nanomolar to 0.2 nanomolar, more preferably, the KD is within a range of 500 nanomolar to 3.5 nanomolar, more preferably, within a range of 150 nanomolar to 3.5 nanomolar. A long term plasma antigen concentration is determined by measuring total or free antigen concentration in plasma and molar antigen/antigen-binding molecule ratio at 2, 4, 7, 14, 28, 56, or 84 days after administration of an antigen-binding molecule in order to evaluate the long term effect of the antigen-binding molecule of the present invention on activity for eliminating antigen in plasma. Whether the reduction of plasma antigen concentration or molar antigen/antigen-binding molecule ratio is achieved by antigen-binding molecule described in the present invention can be determined by the evaluation of the reduction at any one or more of the time points described above.
Still more specifically, those antigen-binding molecules having a short term effect on for eliminating antigen in plasma as described in the present invention have human FcRn-binding activity at pH 7.0 and at 25 degrees Celsius 440-fold stronger than intact human IgG or KD stronger than 0.2 micromolar, preferably stronger than 700 nanomolar, more preferably stronger than 500 nanomolar, most preferably, stronger than 150 nanomolar. A short term plasma antigen concentration is determined by measuring total or free antigen concentration in plasma and molar antigen/antigen-binding molecule ratio at 15 min, 1, 2, 4, 8, 12, or 24 hours after administration of an antigen-binding molecule in order to evaluate the short term effect of the antigen-binding molecule of the present invention on activity for eliminating antigen in plasma.
Route of administration of an antigen-binding molecule of the present invention can be selected from intradermal, intravenous, intravitreal, subcutaneous, intraperitoneal, parenteral and intramuscular injection.
In the context of the present invention, improvement of pharmacokinetics in human is preferred. When the plasma retention in human is difficult to determine, it may be predicted based on the plasma retention in mice (for example, normal mice, human antigen-expressing transgenic mice, human FcRn-expressing transgenic mice) or monkeys (for example, cynomolgus monkeys).
Herein the term “reducing the antigen-binding activity of an antigen-binding molecule in the acidic pH range to less than that in the neutral pH range” means that the antigen-binding activity of the antigen-binding molecule at pH 4.0 to pH 6.5 is impaired as compared to its antigen-binding activity at pH 6.7 to pH 10.0. Preferably, the above phrase means that the antigen-binding activity of an antigen-binding molecule at pH 5.5 to pH 6.5 is impaired as compared to that at pH 7.0 to pH 8.0, more preferably means that its antigen-binding activity at the early endosomal pH is impaired as compared to its antigen-binding activity at the plasma pH in vivo. Specifically, the antigen-binding activity of an antigen-binding molecule at pH 5.8 to pH 6.0 is impaired as compared to the antigen-binding activity of the antigen-binding molecule at pH 7.4. Herein the term “reducing the antigen-binding activity of an antigen-binding molecule in the neutral pH range to less than that in the acidic pH range” means that the antigen-binding activity of the antigen-binding molecule at pH 6.7 to pH 10.0 is impaired as compared to its antigen-binding activity at pH 4.0 to pH 6.5. Preferably, the above phrase means that the antigen-binding activity of an antigen-binding molecule at pH 7.0 to pH 8.0 is impaired as compared to that at pH 5.5 to pH 6.5, more preferably means that its antigen-binding activity at the plasma pH in vivo is impaired as compared to its antigen-binding activity at the early endosomal pH. Specifically, the antigen-binding activity of an antigen-binding molecule at pH 7.4 is impaired as compared to the antigen-binding activity of the antigen-binding molecule at pH 5.8 to pH 6.0.
Meanwhile, herein the expression “reducing the antigen-binding activity of an antigen-binding molecule in the acidic pH range to less than that in the neutral pH range” is also expressed as “increasing the antigen-binding activity of an antigen-binding molecule in the neutral pH range to more than that in the acidic pH range”. Specifically, in the present invention, it is possible to increase the ratio of antigen binding activity of an antigen-binding molecule between acidic and neutral pH ranges. For example, the value of KD (pH 5.8)/KD (pH 7.4) is increased in an embodiment described below. The ratio of antigen-binding activity of an antigen-binding molecule between acidic and neutral pH ranges can be increased, for example, by reducing its antigen-binding activity in the acidic pH range, increasing its antigen-binding activity in the neutral pH range, or both. The expression “reducing the antigen-binding activity of an antigen-binding molecule in the neutral pH range to less than that in the acidic pH range” is also expressed as “increasing the antigen-binding activity of an antigen-binding molecule in the acidic pH range to more than that in the neutral pH range”. Specifically, in the present invention, it is possible to increase the ratio of antigen binding activity of an antigen-binding molecule between acidic and neutral pH ranges. For example, the value of KD (pH7.4)/KD (pH 5.8) is increased in an embodiment described below. The ratio of antigen-binding activity of an antigen-binding molecule between acidic and neutral pH ranges can be increased, for example, by reducing its antigen-binding activity in the neutral pH range, increasing its antigen-binding activity in the acidic pH range, or both.
The term “reducing the antigen-binding activity (binding ability) at low calcium-ion concentrations to less than its antigen-binding activity at high calcium-ion concentration” as used herein refers to decreasing the binding affinity of the antigen-binding domain for the antigen at a low calcium-ion concentration compared with the binding affinity for the antigen of said antigen-binding domain at a high calcium-ion concentration. The low calcium concentration is preferably 0.5 to 10 micromolar, more preferably 0.1 to 30 micromolar of ionized calcium, and the high calcium concentration is 100 micromolar to 10 mM, more preferably 200 micromolar to 5 mM of ionized calcium.
Herein, the expression “impairing the antigen-binding activity in the acidic pH range as compared to that in the neutral pH range” is sometimes used instead of “reducing the antigen-binding activity in the acidic pH range to less than that in the neutral pH range”.
Herein, the human FcRn-binding activity in the acidic pH range means the human FcRn-binding activity at pH 4.0 to pH 6.5, preferably the human FcRn-binding activity at pH 5.5 to pH 6.5, and particularly preferably the human FcRn-binding activity at pH 5.8 to pH 6.0, which is comparable to the in vivo early endosomal pH. Meanwhile, herein the human FcRn-binding activity in the neutral pH range means the human FcRn-binding activity at pH 6.7 to pH 10.0, preferably the human FcRn-binding activity at pH 7.0 to pH 8.0, and particularly preferably the human FcRn-binding activity at pH 7.4, which is comparable to the in vivo plasma pH.
Although the antigen-binding molecule and uses of the present invention are not limited to any particular theory, the relationship between the reduction (impairment) of the antigen-binding ability of antigen-binding molecule in the acidic pH range to less than that in the neutral pH range and/or the increase (enhancement) of the human FcRn-binding activity in the neutral pH range and the increase in the number of antigens to which a single antigen-binding molecule can bind, due to facilitation of uptake of antigen-binding molecules into cells, and the enhancement of antigen elimination from the plasma can be explained as follows.
For example, when the antigen-binding molecule is an antibody that binds to a membrane antigen, the antibody administered into the body binds to the antigen and then is taken up via internalization into endosomes in the cells together with the antigen while the antibody is kept bound to the antigen. Then, the antibody translocates to lysosomes while the antibody is kept bound to the antigen, and the antibody is degraded by the lysosome together with the antigen. The internalization-mediated elimination from the plasma is called antigen-dependent elimination, and such elimination has been reported with numerous antibody molecules (Drug Discov Today. 2006 January; 11(1-2): 81-8). When a single molecule of IgG antibody binds to antigens in a divalent manner, the single antibody molecule is internalized while the antibody is kept bound to the two antigen molecules, and degraded in the lysosome. Accordingly, in the case of typical antibodies, one molecule of IgG antibody cannot bind to three or more molecules of antigen. For example, a single IgG antibody molecule having a neutralizing activity cannot neutralize three or more antigen molecules.
The relatively prolonged retention (slow elimination) of IgG molecules in the plasma is due to the function of human FcRn which is known as a salvage receptor of IgG molecules. When taken up into endosomes via pinocytosis, IgG molecules bind to human FcRn expressed in the endosomes under the acidic condition in the endosomes. While IgG molecules that did not bind to human FcRn transfer to lysosomes where they are degraded, IgG molecules that are bound to human FcRn translocate to the cell surface and return again in the plasma by dissociating from human FcRn under the neutral condition in the plasma.
Alternatively, when the antigen-binding molecule is an antibody that binds to a soluble antigen, the antibody administered into the body binds to the antigen and then is taken up into cells while the antibody is kept bound to the antigen. Many antibodies taken up into cells are released to the outside of the cell via FcRn. However, since the antibodies are released to the outside of the cell, with the antibodies kept bound to antigens, the antibodies cannot bind to antigens again. Thus, similar to antibodies that bind to membrane antigens, in the case of typical antibodies, one molecule of IgG antibody cannot bind to three or more antigen molecules.
pH-dependent antigen-binding antibodies that strongly bind to an antigen under the neutral conditions in plasma but dissociate from the antigen under acidic conditions in the endosome (i.e., antibodies that bind under neutral conditions but dissociate under acidic conditions) can dissociate from the antigen in the endosome. Such pH-dependent antigen-binding antibodies can bind to antigens again when they are recycled to the plasma by FcRn after antigen dissociation; thus, each antibody can repeatedly bind to a number of antigens. Furthermore, the antigen bound to the antigen-binding molecule is dissociated in the endosome and not recycled to the plasma. This facilitates the antigen-binding molecule-mediated antigen uptake into cells. Thus, the administration of an antigen-binding molecule can enhance the antigen elimination and thereby reduces the plasma antigen concentration.
A calcium concentration-dependent antigen-binding antibody, which strongly binds to an antigen under a high calcium concentration condition in plasma, and dissociates from the antigen under a low calcium concentration condition in the endosome, can dissociate from the antigen within the endosome. The calcium concentration-dependent antigen-binding antibody can bind to an antigen again when recycled to plasma via FcRn after antigen dissociation. Thus, such a single antibody can repeatedly bind to multiple antigens. Meanwhile, an antigen bound to the antigen-binding molecule is not recycled to plasma because the antigen dissociates in the endosome, and thus, the antigen-binding molecule promotes uptake of the antigen into cells. The administration of the antigen-binding molecule promotes the elimination of an antigen, and this allows a decrease in the antigen concentration in plasma.
The antigen-binding molecule-mediated antigen uptake into cells can be further facilitated by conferring the human FcRn-binding activity under neutral conditions (pH 7.4) to an antibody that binds to an antigen in a pH-dependent manner (binds under neutral conditions but dissociates under acidic conditions). Thus, the administration of an antigen-binding molecule can enhance the antigen elimination and thereby reduces the plasma antigen concentration. Normally, both antibody and antigen-antibody complex are taken up into cells by non-specific endocytosis, and then transported to the cell surface by binding to FcRn under acidic conditions in the endosome. The antibody and antigen-antibody complex are recycled to the plasma via dissociation from FcRn under the neutral condition on cell surface. Thus, when an antibody that exhibits sufficient pH dependency in antigen binding (binds under neutral conditions but dissociates under acidic conditions) binds to the antigen in the plasma and then is dissociated from the bound antigen in the endosome, the antigen elimination rate is presumed to be equal to the rate of antigen uptake into cells via non-specific endocytosis. On the other hand, when the pH dependency is insufficient, the antigen that did not dissociate in the endosome is also recycled to the plasma. Meanwhile, when the pH dependency is sufficient, the rate-determining step in the antigen elimination is the uptake into cells by non-specific endocytosis. Some of FcRn is presumed to be localized on the cell surface because FcRn transports antibodies from the endosome to the cell surface.
The present inventors presumed that IgG-type immunoglobulins, which are one of antigen-binding molecules, typically have little FcRn-binding ability in the neutral pH range, but those that exhibit FcRn-binding ability in the neutral pH range could bind to FcRn on the cell surface and thus are taken up into cells in an FcRn-dependent manner by binding to cell-surface FcRn. The rate of FcRn-mediated uptake into cells is more rapid than the rate of uptake into cells by non-specific endocytosis. Thus, the rate of antigen elimination can be further accelerated by conferring FcRn-binding ability in the neutral pH range. Specifically, an antigen-binding molecule having FcRn-binding ability in the neutral pH range transports an antigen into cells more rapidly than the typical (intact human) IgG-type immunoglobulin, and then the antigen-binding molecule is dissociated from the antigen in the endosome. The antigen-binding molecule is recycled to the cell surface or plasma, and again binds to another antigen and is taken up into cells via FcRn. The rate of this cycle can be accelerated by improving FcRn-binding ability in the neutral pH range, thereby accelerating the rate of antigen elimination from the plasma. Furthermore, the efficiency can be further improved by reducing the antigen-binding activity of an antigen-binding molecule in the acidic pH range to less than that in the neutral pH range. In addition, the number of antigens to which a single antigen-binding molecule can bind is presumed to increase with an increasing number of cycles achieved by a single antigen-binding molecule. The antigen-binding molecule of the present invention comprises an antigen-binding domain and an FcRn-binding domain. Since the FcRn-binding domain does not affect antigen binding, or in view of the mechanism described above, facilitation of the antigen-binding molecule-mediated antigen uptake into cells can be expected regardless of the type of antigen, and as a result increases the antigen elimination rate by reducing the antigen-binding activity of an antigen-binding molecule in the acidic pH range (binding ability) to less than that in the neutral pH range and/or increasing its FcRn-binding activity at the plasma pH.
In all forgoing uses the antigen-binding molecules of the present invention may also comprise a substitution at position EU256 in addition to a substitution at the mentioned one or more positions. Preferably, the amino acid at position EU256 is substituted with a glutamic acid. Furthermore, all foregoing methods of use may also comprise a substitution at position EU256 in addition to a substitution at the one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436, whereby the amino acid at position EU256 is preferably substituted with a glutamic acid.
In a preferred embodiment of all foregoing uses and methods, the FcRn-binding region is an Fc region in more preferably, it is a human Fc region.
Moreover, the substitution in the amino acid sequence of the parent FcRn-binding domain for increasing the FcRn-binding activity at neutral or acidic pH are preferably at position EU252 and EU434 and one at one or more positions selected from the group consisting of EU238, EU250, EU254, EU255, EU256, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, and EU436. More preferably, the substitutions are at three or more positions wherein said three or more positions are one of the combinations set forth in Tables 2, and 4 to 7. Even more preferably, the substitutions are one of the combinations set forth in Table 3
Furthermore, the foregoing methods of use may additionally comprise a step introducing an amino acid substitution at one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440, and thereby decreasing an increased binding activity for a pre-existing ADA. Preferably, the substitutions are combinations selected from Table 11.
In addition, the forgoing methods of use may also comprise an additional step of introducing in an amino acid substitution in an FcRn-binding domain at one or more positions selected from the group consisting of EU234, EU235, EU236, EU237, EU238, EU239, EU265, EU266, EU267, EU269, EU270, EU271, EU295, EU296, EU297 EU298, EU300, EU324, EU325, EU327, EU328, EU329, EU331, and EU332 (according to the EU numbering system). Preferably, the substitutions L235R/S239K are introduced. Preferably, the substitutions are combinations selected from Table 14.
The antigen-binding molecule of all foregoing uses and method of uses may comprise a pH-dependent antigen-binding domain or a calcium ion-dependent antigen-binding domain. The antigen uptake into cells mediated by the antigen-binding molecules of the present invention is further improved by reducing the antigen-binding activity (binding ability) in the acidic pH range of the above-described antigen-binding molecule to less than its antigen-binding activity in the neutral pH range. Also preferred is the further improvement of the antigen uptake into cells by reducing the antigen-binding activity (binding ability) of the antigen-binding molecule of the present invention at low calcium-ion concentration (i.e. at 0.5 to 10 micromolar.) to less than its antigen-binding activity at high calcium-ion concentration (i.e. 100 micromolar to 10 mM), for example by replacing the antigen-binding domain of the antigen-binding molecule with an ionized calcium-concentration dependent antigen-binding domain. Alternatively, the parent antigen-binding molecule already comprises an ionized calcium-concentration dependent antigen-binding domain. Methods for reducing the antigen-binding activity (binding ability) in the acidic pH range by altering at least one amino acid in the antigen-binding domain of the above-described antigen-binding molecule are described above. Preferably, the antigen-binding domain is altered by substituting histidine for at least one amino acid or inserting at least one histidine into the antigen-binding domain of the above-described antigen-binding molecule which facilitates antigen uptake into cells.
Clearance of modified antigen-binding molecule that has an increased FcRn-binding activity at neutral or acidic pH can be decreased when these modifications increase the antigen-binding molecule's affinity for a pre-existing ADA, e.g. the rheumatoid factor. This means by further modifying such an antibody and thereby decreasing the affinity for a pre-existing ADA, the number of cycles can be increased compared to the antigen-binding molecule before the second modification, and thus before the affinity for a pre-existing ADA was decreased.
Those antigen-binding molecules of the present invention whose affinity for a pre-existing anti-drug antibody is not significantly increased at a neutral pH as compared to a wild type Fc region, in particular those that comprise in the FcRn binding domain an amino acid substitution at one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440, are particularly useful as therapeutic antibodies for treating human patients suffering from an autoimmune disease, transplant rejections (graft-vs.-host disease), other inflammatory diseases and allergic diseases.
An autoimmune disease is an illness that occurs when body tissue is attacked by its own immune system. Examples of autoimmune diseases contemplated herein include systemic lupus erythematosus, lupus nephritis, pemphigoid, pemphigus, dermatomyositis, autoimmune hepatitis, Sjogren syndrome, Hashimoto thyroiditis, rheumatoid arthritis, juvenile (type 1) diabetes, polymyositis, scleroderma, Addison disease, Coeliac disease, Guillain-Barre syndrome, dilated cardiomyopathy, mixed connective tissue disease, Wegener's granulomatosis, anti-phospholipid antibody syndrome, vitiligo, pernicious anemia, glomerulonephritis, and pulmonary fibrosis. Myasthenia gravis, Graves' disease, idiopathic thrombocytopenia purpura, hemolytic anemia, diabetes mellitus, inflammatory bowel disease, Crohn's disease, ulcerative colitis, multiple sclerosis, psoriasis, and drug-induced autoimmune diseases, e.g., drug-induced lupus. Preferably, the autoimmune disease is systemic lupus erythematosus or Lupus nephritis. Transplant rejection include graft-versus-host disease is a process in which a transplant recipient's immune system attacks the transplanted organ or tissue. Other inflammatory and allergic diseases include atherosclerosis and hay fever.
An increased binding affinity for a pre-existing ADA can reduce the clinical utility and efficacy of a therapeutic antibody. As such the utility of a therapeutic antibody can be limited by the pre-existing ADAs, since these ADA can influence their efficacy and pharmacokinetics (e.g. degradation rate). Sometimes this binding can lead to serious side effects. Furthermore, the present invention provides a method for decreasing the binding activity at neutral pH for a pre-existing ADA of antigen-binding domain comprising an Fc region with an increased binding activity for FcRn at neutral or acidic pH and an increased binding activity for a pre-existing ADA at neutral pH.
The present invention also provides the use of the antigen-binding molecules of the present invention comprising a modified FcRn-binding domain for decreasing the binding activity for a pre-existing ADA at neutral pH of an antigen-binding molecule that has an increased affinity for FcRn at neutral or acidic pH and an increased binding activity for a pre-existing ADA.
In particular, the present invention provides a method for decreasing the binding activity at neutral pH for a pre-existing ADA of an Fc region of an antigen-binding molecule that has an increased binding activity for FcRn at neutral or acidic pH, said method comprising
a) providing a Fc region having an increased binding activity for FcRn at neutral or acidic pH and for a pre-existing ADA at neutral pH and
b) substituting an amino acid at one or more of the positions selected from the group consisting of: EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440. The preferred Fc region in step a) is a human Fc region. Preferably, the Fc region having an increased binding activity for FcRn at neutral or acidic pH ranges and for pre-existing ADA in the neutral pH ranges comprises a substitution of an amino acid at one or more positions selected from the group consisting of: EU238, EU250, EU252, EU254, EU255, EU256, EU258 EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436. More preferably, it comprises a substitution at the positions at any one of the combinations of positions selected from Table 2 and 4 to 7. Even more preferably, it comprises any one of the substitutions or combinations of substitutions set forth in any one of Tables 3 and 17 to 20.
Preferably, step b) comprises substituting an amino acid at any one of the positions in Table 8. More preferably, step b) comprises introducing one of the substitutions or combinations selected from Table 11.
Also preferably, the antigen-binding molecule comprises additionally a pH-dependent antigen-binding domain or a calcium ion-dependent antigen-binding domain.
Moreover, the present invention provides a method for decreasing the binding activity for a pre-existing ADA of an antigen-binding molecule that comprises an Fc region having an increased binding activity for FcRn at neutral pH, said method comprising the steps of:
a) providing an antigen-binding molecule comprising a Fc region with an increased binding activity for FcRn at acidic pH and for a pre-existing ADA at a neutral pH and
b) substituting an amino acid in the Fc region at one or more of the positions selected from the group consisting of: EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
The preferred Fc region in step a) is a human Fc region. Preferably, the Fc region having an increased binding activity for FcRn at neutral pH ranges and for pre-existing ADA in the neutral pH ranges comprises a substitution of an amino acid at one or more positions selected from the group consisting of: EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436. It may also comprise a substitution at position EU256 in addition to a substitution at the one or more positions mentioned above, whereby the amino acid at position EU256 is preferably substituted with a glutamic acid. More preferably, it comprises a substitution at the positions of any one of the position combinations selected from Tables 2 and 4 to 7. Even more preferably, it comprises any one of the substitutions or substitution combinations selected from any one of Table 3 and 17 to 20.
Preferably, step b) comprises substituting an amino acid at any one of the positions in Table 10. More preferably, the positions are selected from the group consisting of a) EU387, b) EU422, c) EU424, d) EU438, e) EU440, f) EU422/EU424, and g) EU438/EU440. Even more preferably, step b) comprises introducing one of the substitutions or combinations selected from Table 11.
Moreover, the present invention provides a method for decreasing the binding activity for a pre-existing ADA of an antigen-binding molecule that comprises an Fc region having an increased binding activity for FcRn at acidic pH, said method comprising the steps of:
a) providing an antigen-binding molecule comprising a Fc region with an increased binding activity for FcRn at acidic pH and for a pre-existing ADA at a neutral pH and
b) substituting an amino acid in the Fc region at one or more of the positions selected from the group consisting of: EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
The preferred Fc region in step a) is a human Fc region. Preferably, the Fc region having an increased binding activity for FcRn at acidic pH and for pre-existing ADA in the neutral pH ranges comprises an amino acid substitution comprise a substitution
i) at position EU434, or
ii) at two or more positions, wherein the two or more positions are one of the combinations of the group consisting of a) EU252/EU254/EU256; b) EU428/EU434; and c) EU250/EU428. Preferably, the Fc region comprises i) the substitution M434H; or ii) one of the combinations of the group consisting of a) M252Y/S254T/T256E; b) M428L/N434S; and c) T250Q and M428L (EU numbering).
In a preferred embodiment, in step b) an amino acid is substituted at a) position EU424 or b) the positions EU438/EU440. More preferably, the substitutions are a) EU424N or b) the combination EU438R/EU440E.
In a further preferred embodiment, the methods for decreasing the binding activity for a pre-existing ADA further comprises the step c) confirming that said antigen-binding molecule with a modified Fc domain has a decreased binding activity for an endogenous ADA as compared the binding activity for the original antigen-binding molecule as set forth in step a) comprised of an intact Fc domain.
Also preferably, the antigen-binding molecule comprises additionally a pH-dependent antigen-binding domain or a Calcium ion-dependent antigen-binding domain.
The present invention provides the use of an antigen-binding molecule of the present invention for increasing antigen removal from blood of a mammal, preferably a human patient suffering from an autoimmune disease.
The present invention further provides a method for increasing the total number of antigens to which a single antigen-binding molecule can bind without significantly increasing the binding activity for a pre-existing ADA at neutral pH as compared to a parent antibody, said method comprising the steps of
a) providing an antigen-binding molecule comprising a parent FcRn binding domain,
b) altering the parent FcRn binding domain of step a) by substituting an amino acid in the amino acid sequence of the parent FcRn binding domain at one or more of the positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258 EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436; and
c) altering the modified FcRn-binding domain of step b) by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
The present invention further provides a method for facilitating the extracellular release of an antigen-free antigen-binding molecule taken up into cells in an antigen-bound form without significantly increasing the binding activity of said antigen-binding molecule for a pre-existing ADA at neutral pH as compared to a parent antibody, comprising the steps of
a) providing an antigen-binding molecule comprising a parent FcRn-binding domain,
b) altering the parent FcRn binding domain by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258 EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436, and EU428; and
c) altering the modified FcRn-binding domain of step b) by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
The present invention further provides a method for increasing the ability of an antigen-binding molecule to eliminate plasma antigen without significantly increasing the binding activity for pre-existing ADA at neutral pH compared to parent antibody, said method comprising the steps of
a) providing an antigen-binding molecule comprising a parent FcRn-binding domain,
b) altering the parent FcRn binding domain by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258 EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436, and EU428; and
c) altering the modified FcRn-binding domain of step b) by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
The present invention further provides a method for improving the pharmacokinetics of an antigen-binding molecule without significantly increasing the binding activity for a pre-existing ADA at neutral pH as compared to a parent antibody, said method comprising the steps of
a) providing an antigen-binding molecule comprising a parent FcRn-binding domain,
b) altering the parent FcRn-binding domain by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258 EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436; and
c) altering the modified FcRn-binding domain of step b) by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
The present invention further provides a method for reducing total or free antigen plasma concentration without significantly increasing the binding activity for a pre-existing ADA at neutral pH as compared to a parent antibody, said method comprising the steps of
a) providing an antigen-binding molecule comprising a parent FcRn-binding domain, wherein the antigen-binding molecule comprises an antigen-binding domain which can bind said antigen,
b) altering the parent FcRn-binding domain by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258 EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436; and
c) altering the modified FcRn-binding domain of step b) by substituting an amino acid in the amino acid sequence of the parent FcRn-binding domain at one or more positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
The preferred Fc region in step a) in the foregoing methods of use is a human Fc region. In a preferred embodiment, the amino acid substitution at one or more positions in step b) is a substitution at one or more positions selected from the group consisting of: EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436, whereby the Fc region of step b) has an increased binding activity for FcRn and a pre-existing ADA in the neutral pH ranges. It may also comprise a substitution at position EU256 in addition to a substitution at the one or more positions mentioned above, whereby the amino acid at position EU256 is preferably substituted with a glutamic acid. More preferably, it comprises a substitution at the positions of any one of the position combinations selected from Tables 2 and 4 to 7. Even more preferably, it comprises any one of the substitutions or substitution combinations selected from any one of Table 3 and 17 to 20.
Preferably, step c) comprises substituting an amino acid at any one of the positions in Table 10. More preferably, the positions are selected from the group consisting of a) EU387, b) EU422, c) EU424, d) EU438, e) EU440, f) EU422/EU424, and g) EU438/EU440. Even more preferably, step c) comprises introducing one of the substitutions or combinations selected from Table 11.
In another preferred embodiment, the amino acid substitution at one or more positions in step b) is a substitution
i) at position EU434, or
ii) at two or more positions, wherein the two or more positions are one of the combinations of the group consisting of a) EU252/EU254/EU256; b) EU428/EU434; and c) EU250/EU428, whereby the Fc region of step b) has an increased FcRn-binding activity in the acidic ranges and an increased binding activity for a pre-existing ADA in the neutral pH ranges. Preferably, the Fc region comprises i) the substitution M434H; or
ii) one of the combinations of the group consisting of a) M252Y/S254T/T256E; b) M428L/N434S; and c) T250Q and M428L (EU numbering). In a preferred embodiment, in step c) an amino acid is substituted at a) position EU424 or b) the positions EU438/EU440. More preferably, the substitutions are a) EU424N or b) the combination EU438R/EU440E.
The present invention also relates to pharmaceutical compositions that include antigen-binding molecules of the present invention, or antigen-binding molecules produced by the production methods of the present invention. The antigen-binding molecules of the present invention and antigen-binding molecules produced by the production methods of the present invention have greater activity to reduce plasma antigen concentration by administration as compared to typical antigen-binding molecules, and are therefore useful as pharmaceutical compositions. The pharmaceutical composition of the present invention may include pharmaceutically acceptable carriers. In the present invention, pharmaceutical compositions ordinarily refer to agents for treating or preventing, or testing and diagnosing diseases.
The pharmaceutical compositions of the present invention can be formulated by methods known to those skilled in the art. For example, they can be used parenterally, in the form of injections of sterile solutions or suspensions including water or other pharmaceutically acceptable liquid. For example, such compositions may be formulated by mixing in the form of unit dose required in the generally approved medicine manufacturing practice by appropriately combining with pharmaceutically acceptable carriers or media, specifically with sterile water, physiological saline, vegetable oil, emulsifier, suspension, surfactant, stabilizer, flavoring agent, excipient, vehicle, preservative, binder, or such. In such formulations, the amount of active ingredient may be readily and routinely adjusted to obtain an appropriate amount in a pre-determined range.
Sterile compositions for injection can be formulated using vehicles such as distilled water for injection, according to standard formulation practice. Aqueous solutions for injection include, for example, physiological saline and isotonic solutions containing dextrose or other adjuvants (for example, D-sorbitol, D-mannose, D-mannitol, and sodium chloride). It is also possible to use in combination appropriate solubilizers, for example, alcohols (ethanol and such), polyalcohols (propylene glycol, polyethylene glycol, and such), non-ionic surfactants (polysorbate 80™, HCO-50, and such).
Oils include sesame oil and soybean oils. Benzyl benzoate and/or benzyl alcohol can be used in combination as solubilizers. It is also possible to combine buffers (for example, phosphate buffer and sodium acetate buffer), soothing agents (for example, procaine hydrochloride), stabilizers (for example, benzyl alcohol and phenol), and/or antioxidants. Appropriate ampules are filled with the prepared injections.
The pharmaceutical compositions of the present invention are preferably administered parenterally. For example, the compositions may be in the dosage form for injections, transnasal administration, transpulmonary administration, or transdermal administration. Such compositions may be administered systemically or locally by intravenous injection, intramuscular injection, intraperitoneal injection, subcutaneous injection, or such.
Administration methods can be appropriately selected in consideration of the patient's age and symptoms. The dose of a pharmaceutical composition containing an antigen-binding molecule may be, for example, from 0.0001 to 1,000 mg/kg for each administration. Alternatively, the dose may be, for example, from 0.001 to 100,000 mg per patient. However, the present invention is not limited by the numeric values described above. The doses and administration methods vary depending on the patient's weight, age, symptoms, and such. Those skilled in the art can set appropriate doses and administration methods in consideration of the factors described above.
Amino acids contained in the amino acid sequences of the present invention may be post-translationally modified. For example, the modification of an N-terminal glutamine into a pyroglutamic acid by pyroglutamylation is well-known to those skilled in the art. Naturally, such post-translationally modified amino acids are included in the amino acid sequences in the present invention.
The present invention provides methods for producing antigen-binding molecules of the present invention. In particular, the present invention provides a method for producing antigen-binding molecules having an FcRn-binding domain with an increased binding activity for FcRn at neutral pH as compared to an antigen-binding molecule comprising a wild type Fc region.
The present invention provides a method for producing an antigen-binding molecule, which comprises the steps of:
(a) selecting a parent FcRn-binding domain and altering the parent FcRn with a substitution of an amino acid in the amino acid sequence with another amino acid at one or more positions selected from the group consisting of EU252, EU434, EU436, EU315, EU311, EU308, EU307, EU286, EU254, EU250, EU238, EU387, EU422, EU424, EU428, EU438 and EU440;
(b) selecting an antigen-binding domain of an antigen-binding molecule and altering at least one amino acid in the antigen-binding domain in order to get a pH-dependent antigen-binding domain or a calcium-ion dependent antigen-binding domain;
(c) obtaining a gene encoding an antigen-binding molecule in which the human FcRn-binding domain and the antigen-binding domain prepared in (a) and (b) are linked; and
(d) producing an antigen-binding molecule using the gene prepared in (c).
Preferably, the selected antigen-binding molecule comprises an antigen-binding domain that has a lower binding activity for the antigen at a pH 5.5-6.5 than at pH 7-8 or has a calcium dependent antigen binding activity. Preferably, the FcRn-binding domain of step a) is a FcRn-binding domain of the present invention. More preferably, the FcRn-binding domain comprises an amino acid substations at three or more positions, wherein said three or more positions are one of the combinations set forth in Tables 2, and 4 to 7. Even more preferably, the FcRn-binding domain comprises three or more substitutions wherein said three or more substitutions are one of the combinations set forth in Tables 3, 17 to 20.
Steps (a) may comprise substituting an amino acid substitution at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436 and selecting a FcRn-binding domain that has stronger human FcRn-binding activity in the neutral pH range than KD 3.2 micromolar.
Step (b) may comprise selecting an antigen-binding domain and altering at least one amino acid in the antigen-binding domain as described above in order to get a pH-dependent antigen-binding domain, or selecting a calcium-ion dependent antigen-binding domain. Altering an amino acid is preferably substituting histidine for at least one amino acid or inserting at least one histidine. Meanwhile, the site where the at least one histidine mutation is introduced is not particularly limited, and thus it may be introduced at any position as long as the histidine mutation reduces the antigen-binding activity in the acidic pH range to less than that in the neutral pH range. Such histidine mutations may be introduced at a single site or two or more sites. Steps a) and b) may be repeated twice or more times. The number of times of repeating steps (a) and (b) is not particularly limited; however, the number is typically ten times or less.
A linker operably linking the FcRn-binding domain and the antigen-binding domain prepared in (a) and (b) is not limited to any form. The human FcRn-binding domain and the antigen-binding domain can be linked by either covalent or non-covalent forces. In particular, the linker can be a peptide linker or a chemical linker or a binding pair like a combination of biotin and streptavidin. Modification of a polypeptide including the human FcRn-binding domain and the antigen-binding domain is known in the art. In another embodiment, the human FcRn-binding domain and the antigen-binding domain of the present invention can be linked by forming a fusion protein between the human FcRn-binding domain and the antigen-binding domain. In order to construct fusion protein between the human FcRn-binding domain and the antigen-binding domain, genes encoding the human FcRn-binding domain and the antigen-binding domain can be operationally linked so as to form in frame fusion polypeptide. Appropriately, a linker comprising peptide consisting of several amino acids can be inserted between the human FcRn-binding domain and the antigen-binding domain. Various flexible linkers like the linker whose sequence consists of (GGGGS)n (SEQ ID NO: 11) is known in the art.
The present invention further provides a method for producing an antigen-binding molecule comprising an FcRn-binding domain with an increased binding activity for FcRn at neutral or acidic pH without a significantly increased binding activity for a pre-existing ADA at neutral pH compared to an antigen-binding molecule comprising a wild type Fc region.
Preferably, the methods for producing an antigen-binding molecule comprising a Fc region with an increased binding activity for FcRn at neutral or acidic pH and a decreased binding activity for an pre-existing ADA at neutral pH, comprises the steps of:
(a) providing a Fc region having an increased binding activity for FcRn in the neutral or acidic pH ranges and an increased binding activity for a pre-existing ADA in the neutral pH ranges,
b) substituting an amino acid in the amino acid sequence of the Fc region at one or more of the positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440.
(c) altering at least one amino acid in the antigen-binding domain of an antigen-binding molecule and selecting an antigen-binding molecule that has stronger antigen-binding activity in the neutral pH range than in the acidic pH range;
(d) obtaining a gene encoding an antigen-binding molecule in which the human FcRn-binding domain prepared in (b) and the antigen-binding domain prepared in (c) are linked and
(e) producing an antigen-binding molecule using the gene prepared in (d).
The preferred Fc region in step a) is a human Fc region. Preferably, the Fc region having an increased binding activity for FcRn and pre-existing ADA at neutral or acidic pH ranges and for pre-existing ADA in the neutral pH ranges comprises a substitution of an amino acid at one or more positions selected from the group consisting of: EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436. More preferably, it comprises substitutions at the positions of any one of the position combinations selected from Tables 2 and 4 to 7. Even more preferably, it comprises any one of the substitutions or combinations of substitutions set forth in any one of Tables 3 and 17 to 20. Preferably, step a) includes providing a nucleotide sequence encoding an Fc region having an increased binding activity for FcRn and pre-existing ADA at neutral or acidic pH ranges. Preferably, the substitutions in step b) amino acid substitutions at one or more positions or a position combination as set forth in Table 10. More preferably, the substitutions of step b) are one of the substitution combinations set forth in Table 11. The amino acid at one or more of the positions selected from the group consisting of EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440 in step b) is preferably substituted by replacing one or more nucleotides in the nucleotide sequence.
Steps (b) and (c) may be carried out in either order. Furthermore, step c) may comprise altering at least one amino acid in the antigen-binding domain as described above in order to get a pH-dependent antigen-binding domain, or selecting a calcium-ion dependent antigen-binding domain. In step (c), altering an amino acid is preferably substituting histidine for at least one amino acid or inserting at least one histidine. Meanwhile, the site where the at least one histidine mutation is introduced is not particularly limited, and thus it may be introduced at any position as long as the histidine mutation reduces the antigen-binding activity in the acidic pH range to less than that in the neutral pH range. Such histidine mutations may be introduced at a single site or two or more sites. Steps b) and c) may be repeated twice or more times. The number of times of repeating steps (b) and (c) is not particularly limited; however, the number is typically ten times or less.
A linker operably linking the FcRn-binding domain and the antigen-binding domain prepared in (b) and (c) is not limited to any form. The human FcRn-binding domain and the antigen-binding domain can be linked by either covalent or non-covalent forces. In particular, the linker can be a peptide linker or a chemical linker or a binding pair like a combination of biotin and streptavidin. Modification of a polypeptide including the human FcRn-binding domain and the antigen-binding domain is known in the art. In another embodiment, the human FcRn-binding domain and the antigen-binding domain of the present invention can be linked by forming a fusion protein between the human FcRn-binding domain and the antigen-binding domain. In order to construct the fusion protein between the human FcRn-binding domain and the antigen-binding domain, genes encoding the human FcRn-binding domain and the antigen-binding domain can be operationally linked so as to form in frame fusion polypeptide. Appropriately, a linker comprising peptide consisting of several amino acids can be inserted between the human FcRn-binding domain and the antigen-binding domain. Various flexible linkers like the linker whose sequence consists of (GGGGS)n (SEQ ID NO: 11) is known in the art.
Thus, the production methods of the present invention may further comprise the steps of altering the above-described amino acids and substituting or inserting histidine. In the production methods of the present invention, non-natural amino acids may be used instead of histidine. Therefore, the present invention can also be understood by replacing the above-mentioned histidine with non-natural amino acids.
Step a) of the production methods of the present invention may also comprise a substitution at position EU256 in addition to a substitution at the one or more positions mentioned above, whereby the amino acid at position EU256 is preferably substituted with a glutamic acid.
Furthermore, the production methods of the present invention may further comprise a step comprising substituting an amino acid in the amino acid sequence of the Fc region at one or more of the positions selected from the group consisting of EU234, EU235, EU236, EU237, EU238, EU239, EU265, EU266, EU267, EU269, EU270, EU271, EU295, EU296, EU297 EU298, EU300, EU324, EU325, EU327, EU328, EU329, EU331, and EU332 (according to the EU numbering system). Preferably, the substitutions L235R/S239K are introduced.
Parent FcRn-binding domains and antigen-binding molecules comprising them that are used in the production methods of the present invention may be prepared by any method. For example, it is possible to use pre-existing antibodies, pre-existing libraries (phage libraries and the like), antibodies and libraries that are prepared from hybridomas obtained by immunizing animals or from B cells of immunized animals, antibodies and libraries prepared by introducing random amino acid alterations into the above-described antibodies and libraries, antibodies and libraries prepared by introducing histidine or non-natural amino acid mutations into the above-described antibodies and libraries (libraries with high content of histidine or non-natural amino acid, libraries introduced with histidine or non-natural amino acid at specific sites, and the like), and such.
The antigen-binding activity and human FcRn binding activity of an antigen-binding molecule can be determined by methods known to those skilled in the art. Conditions except for pH can be appropriately determined by those skilled in the art.
In the above-described production methods, the antigen and antigen-binding molecule may bind to each other in any state, and the human FcRn and antigen-binding molecule may bind to each other in any state. The state is not particularly limited; for example, the antigen or human FcRn may be contacted with an immobilized antigen-binding molecule to bind the antigen-binding molecule. Alternatively, the antigen-binding molecule may be contacted with an immobilized antigen or human FcRn to bind the antigen-binding molecule. Alternatively, the antigen-binding molecule may be contacted with the antigen or human FcRn in a solution to bind the antigen-binding molecule.
The antigen-binding molecules produced by the above-described methods may be any antigen-binding molecule of the present invention; and preferred antigen-binding molecules include, for example, those having an antigen-binding domain which is an ionized calcium-concentration dependent antigen-binding domain or an antigen-binding domain with histidine substitution for amino acid(s) or insertion of at least one histidine, and said antigen-binding molecule further comprising a human FcRn-binding domain, which comprise an amino acid substitution at one or more positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436 (EU numbering). The antigen-binding molecule of the present invention may also comprise a substitution at position EU256 in addition to a substitution at the one or more positions mentioned above. Preferably, the amino acid at position EU256 is substituted with a glutamic acid. More preferably, the FcRn-binding domain comprises an amino acid substations at three or more positions, wherein said three or more positions are one of the combinations set forth in Tables 2, and 4 to 7. Even more preferably, the FcRn-binding domain comprises three or more substitutions wherein said three or more substitutions are one of the combinations set forth in Tables 3, 17 to 20.
Further preferred antigen-binding molecules include for example, those having an antigen-binding domain which is an ionized calcium-concentration dependent antigen-binding domain or an antigen-binding domain with histidine substitution for amino acid(s) or insertion of at least one histidine, and said antigen-binding molecule further comprising a human Fc region with substitutions of the amino acid at one or more of the positions selected from the group consisting of: EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440. More preferably, the FcRn-binding domain contains substitutions of an amino acid in the human FcRn-binding domain at three or more positions wherein said three or more positions are one of the combinations set forth in Tables 9 and 10.
A more preferred antigen-binding molecule includes those having those having an antigen-binding domain which is an ionized calcium-concentration dependent antigen-binding domain or an antigen-binding domain with histidine substitution for amino acid(s) or insertion of at least one histidine, and said antigen-binding molecule further comprising a human Fc region with substitutions of the amino acid
a) at one or more of the positions selected from the group consisting of EU238, EU250, EU252, EU254, EU255, EU256, EU258, EU286, EU307, EU308, EU309, EU311, EU315, EU428, EU433, EU434, and EU436, and
b) at one or more of the positions selected from the group consisting of: EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440 (EU numbering).
Preferably, the amino acid at position EU256 is substituted with a glutamic acid. More preferably, the antigen-binding molecules comprise a substitution combination set forth in Tables 11 to 13.
An antibody having a desired activity may be selected by screening from a number of antibodies obtained from the antibody libraries or hybridomas described below.
When altering amino acids in an antigen-binding molecule, it is possible to use a known sequence for the amino acid sequence of an antigen-binding molecule before alteration or the amino acid sequence of an antigen-binding molecule newly identified by methods known to those skilled in the art. For example, when the antigen-binding molecule is an antibody, it can be obtained from antibody libraries or by cloning an antibody-encoding gene from monoclonal antibody-producing hybridomas.
Regarding antibody libraries, many antibody libraries are already known, and methods for producing antibody libraries are also known; therefore, those skilled in the art can appropriately obtain antibody libraries. For example, regarding phage libraries, one can refer to the literature such as Clackson et al., Nature (1991) 352: 624-8; Marks et al., J. Mol. Biol. (1991) 222: 581-97; Waterhouses et al., Nucleic Acids Res. (1993) 21: 2265-6; Griffiths et al., EMBO J. (1994) 13: 324.0-60; Vaughan et al., Nature Biotechnology (1996) 14: 309-14; and Japanese Patent Kohyo Publication No. (JP-A) H20-504970 (unexamined Japanese national phase publication corresponding to a non-Japanese international publication). In addition, it is possible to use known methods, such as methods using eukaryotic cells as libraries (WO 95/15393) and ribosome display methods. Furthermore, technologies to obtain human antibodies by panning using human antibody libraries are also known. For example, variable regions of human antibodies can be expressed on the surface of phages as single chain antibodies (scFvs) using phage display methods, and phages that bind to antigens can be selected. Genetic analysis of the selected phages can determine the DNA sequences encoding the variable regions of human antibodies that bind to the antigens. Once the DNA sequences of scFvs that bind to the antigens is revealed, suitable expression vectors can be produced based on these sequences to obtain human antibodies. These methods are already well known, and one can refer to WO 92/01047, WO 92/20791, WO 93/06213, WO 93/11236, WO 93/19172, WO 95/01438, and WO 95/15388.
As for methods for obtaining genes encoding antibodies from hybridomas, known technologies may be basically used, which involve the use of desired antigens or cells expressing the desired antigens as sensitizing antigens, using these to perform immunizations according to conventional immunization methods, fusing the resulting immune cells with known parent cells by conventional cell fusion methods, screening monoclonal antibody producing cells (hybridomas) by conventional screening methods, synthesizing cDNAs of antibody variable regions (V regions) from mRNAs of the obtained hybridomas using reverse transcriptase, and linking them with DNAs encoding the desired antibody constant regions (C regions).
More specifically, sensitizing antigens to obtain the above-described antigen-binding molecule genes encoding the H chains and L chains may include, for example, both complete antigens with immunogenicity and incomplete antigens including haptens and the like with no immunogenicity; however they are not limited to these examples. For example, it is possible to use whole proteins and partial peptides of proteins of interest. In addition, it is known that substances comprising polysaccharides, nucleic acids, lipids, and such can be antigens. Thus, the antigens of the antigen-binding molecules of the present invention are not particularly limited. The antigens can be prepared by methods known to those skilled in the art, for example, by baculovirus-based methods (for example, WO 98/46777) and such. Hybridomas can be produced, for example, by the method of Milstein et al. (G. Kohler and C. Milstein, Methods Enzymol. (1981) 73: 3-46) and such. When the immunogenicity of an antigen is low, immunization may be performed after linking the antigen with a macromolecule having immunogenicity, such as albumin. Alternatively, if necessary, antigens may be converted into soluble antigens by linking them with other molecules. When transmembrane molecules such as membrane antigens (for example, receptors) are used as antigens, portions of the extracellular regions of the membrane antigens can be used as a fragment, or cells expressing transmembrane molecules on their cell surface may be used as immunogens.
Antigen-binding molecule-producing cells can be obtained by immunizing animals using appropriate sensitizing antigens described above. Alternatively, antigen-binding molecule-producing cells can be prepared by in vitro immunization of lymphocytes that can produce antigen-binding molecules. Various mammals can be used for immunization; such commonly used animals include rodents, lagomorphas, and primates. Such animals include, for example, rodents such as mice, rats, and hamsters; lagomorphas such as rabbits; and primates including monkeys such as cynomolgus monkeys, rhesus monkeys, baboons, and chimpanzees. In addition, transgenic animals carrying human antibody gene repertoires are also known, and human antibodies can be obtained by using these animals (see WO 96/34096; Mendez et al., Nat. Genet. (1997) 15: 146-56). Instead of using such transgenic animals, for example, desired human antibodies having binding activity against antigens can be obtained by in vitro sensitization of human lymphocytes with desired antigens or cells expressing the desired antigens, and then fusing the sensitized lymphocytes with human myeloma cells such as U266 (see Japanese Patent Application Kokoku Publication No. (JP-B) H01-59878 (examined, approved Japanese patent application published for opposition)). Furthermore, desired human antibodies can be obtained by immunizing transgenic animals carrying a complete repertoire of human antibody genes, with desired antigens (see WO 93/12227, WO 92/03918, WO 94/02602, WO 96/34096, and WO 96/33735).
Animal immunization can be carried out by appropriately diluting and suspending a sensitizing antigen in phosphate buffered saline (PBS), physiological saline, or such, and mixing it with an adjuvant to emulsify, if necessary. This is then intraperitoneally or subcutaneously injected into animals. Then, the sensitizing antigen mixed with Freund's incomplete adjuvant is preferably administered several times every four to 21 days. Antibody production can be confirmed by measuring the titer of the antibody of interest in animal sera using conventional methods.
Antigen-binding molecule-producing cells obtained from lymphocytes or animals immunized with a desired antigen can be fused with myeloma cells to generate hybridomas using conventional fusing agents (for example, polyethylene glycol) (Goding, Monoclonal Antibodies: Principles and Practice, Academic Press, (1986) 59-103). When required, hybridoma cells can be cultured and grown, and the binding specificity of the antigen-binding molecule produced from these hybridomas can be measured using known analysis methods, such as immunoprecipitation, radioimmunoassay (RIA), and enzyme-linked immunosorbent assay (ELISA). Thereafter, if necessary, hybridomas producing antigen-binding molecules of interest whose specificity, affinity, or activity has been determined can be subcloned by methods such as limiting dilution.
Next, genes encoding the selected antigen-binding molecules can be cloned from hybridomas or antigen-binding molecule-producing cells (sensitized lymphocytes, and such) using probes that can specifically bind to the antigen-binding molecules (for example, oligonucleotides complementary to sequences encoding the antibody constant regions). It is also possible to clone the genes from mRNA using RT-PCR. Immunoglobulins are classified into five different classes, IgA, IgD, IgE, IgG, and IgM. These classes are further divided into several subclasses (isotypes) (for example, IgG-1, IgG-2, IgG-3, and IgG-4; IgA-1 and IgA-2; and such). H chains and L chains used in the present invention to produce antigen-binding molecules are not particularly limited and may originate from antibodies belonging to any of these classes or subclasses; however, IgG is particularly preferred.
Herein, it is possible to alter H-chain-encoding genes and L-chain-encoding genes using genetic engineering technologies. Genetically altered antibodies, such as chimeric antibodies and humanized antibodies, which have been artificially altered for the purpose of decreasing heterologous immunogenicity and such against humans, can be appropriately produced for antibodies such as mouse antibodies, rat antibodies, rabbit antibodies, hamster antibodies, sheep antibodies, and camel antibodies. Chimeric antibodies are antibodies including H-chain and L-chain variable regions of nonhuman mammal antibody, such as mouse antibody, and the H-chain and L-chain constant regions of human antibody. Chimeric antibodies can be obtained by ligating a DNA encoding a variable region of a mouse antibody to a DNA encoding a constant region of a human antibody, inserting this into an expression vector, and introducing the vector into a host to produce the antibody. A humanized antibody, which is also called a reshaped human antibody, can be synthesized by PCR using several oligonucleotides produced so that they have overlapping portions at the ends of DNA sequences designed to link the complementarity determining regions (CDRs) of an antibody of a nonhuman mammal such as a mouse. The resulting DNA can be ligated to a DNA encoding a human antibody constant region. The ligated DNA can be inserted into an expression vector, and the vector can be introduced into a host to produce the antibody (see EP 239400 and WO 96/02576). Human antibody FRs that are ligated via the CDR are selected when the CDR forms a favorable antigen-binding site. If necessary, amino acids in the framework region of an antibody variable region may be replaced such that the CDR of the reshaped human antibody forms an appropriate antigen-binding site (K. Sato et al., Cancer Res. (1993) 53: 10.01-10.06).
In addition to the humanization described above, antibodies may be altered to improve their biological properties, for example, the binding to the antigen. In the present invention, such alterations can be achieved by methods such as site-directed mutagenesis (see for example, Kunkel (1910.0) Proc. Natl. Acad. Sci. USA 82: 488), PCR mutagenesis, and cassette mutagenesis. In general, mutant antibodies whose biological properties have been improved show amino acid sequence homology and/or similarity of 70% or higher, more preferably 80% or higher, and even more preferably 90% or higher (for example, 95% or higher, 97%, 98%, or 99%), when compared to the amino acid sequence of the original antibody variable region. Herein, sequence homology and/or similarity is defined as the ratio of amino acid residues that are homologous (same residue) or similar (amino acid residues classified into the same group based on the general properties of amino acid side chains) to the original antibody residues, after the sequence homology value has been maximized by sequence alignment and gap introduction, if necessary. In general, natural amino acid residues are classified into groups based on the characteristics of their side chains as follows:
(1) hydrophobic: alanine, isoleucine, valine, methionine, and leucine;
(2) neutral hydrophilic: asparagine, glutamine, cysteine, threonine, and serine;
(3) acidic: aspartic acid and glutamic acid;
(4) basic: arginine, histidine, and lysine;
(5) residues that affect the orientation of the chain: glycine, and proline; and
(6) aromatic: tyrosine, tryptophan, and phenylalanine
Furthermore, the present invention provides genes encoding the FcRn-binding domain of the present invention and the antigen-binding molecules of the present invention. The genes encoding the antigen-binding molecules of the present invention may be any genes, and may be DNAs, RNAs, nucleic acid analogs, or the like.
Furthermore, the present invention also provides host cells carrying the genes described above. The host cells are not particularly limited and include, for example, E. coli and various animal cells. The host cells may be used, for example, as a production system to produce and express the antibodies of the present invention. In vitro and in vivo production systems are available for polypeptide production systems. Such in vitro production systems include, for example, production systems using eukaryotic cells or prokaryotic cells.
Eukaryotic cells that can be used as host cells include, for example, animal cells, plant cells, and fungal cells. Animal cells include: mammalian cells, for example, CHO(Chinese hamster ovary cell line), COS (Monkey kidney cell line), myeloma (Sp2/O, NS0 etc), BHK (baby hamster kidney cell line) Hela, Vero, HEK293 (human embryonic kidney cell line with sheared adenovirus (Ad)5 DNA), PER.C6 cell (human embryonic retinal cell line transformed with the Adenovirus Type 5 (Ad5) E1A and E1B genes) 293, etc (see Current Protocols in Protein Science (May, 2001, Unit 5.9, Table 5.9.1)), amphibian cells such as Xenopus laevis oocytes (Valle et al., Nature (1981) 291: 338-340); and insect cells such as Sf9, Sf21, and Tn5.CHO-DG44, CHO-DX11B, COS7 cells, HEK293 cells, and BHK cells are preferably used to express the antibodies of the present invention. Among animal cells, CHO cells are particularly preferable for large-scale expression. Vectors can be introduced into host cells, for example, by calcium phosphate methods, DEAE-dextran methods, methods using cationic liposome DOTAP (Boehringer-Mannheim), electroporation methods, and lipofection methods.
Regarding plant cells, for example, Nicotiana tabacum-derived cells and duckweed (Lemna minor) are known as a protein production system. Calluses can be cultured from these cells to produce the antigen-binding molecules of the present invention. Regarding fungal cells, known protein expression systems are those using yeast cells, for example, cells of genus Saccharomyces (such as Saccharomyces cerevisiae and Saccharomyces pombe); and cells of filamentous fungi, for example, genus Aspergillus (such as Aspergillus niger). These cells can be used as a host to produce the antigen-binding molecules of the present invention.
Bacterial cells can be used in the prokaryotic production systems. Regarding bacterial cells, production systems using Bacillus subtilis are known in addition to the production systems using E. coli described above. Such systems can be used in producing the antigen-binding molecules of the present invention.
Genes obtained by the production methods of the present invention are typically carried by (inserted into) appropriate vectors, and then introduced into host cells. The vectors are not particularly limited as long as they stably retain the inserted nucleic acids. For example, when E. coli is used as the host, preferred cloning vectors include pBluescript vector (Stratagene); however, various commercially available vectors may be used. When using vectors to produce the antigen-binding molecules of the present invention, expression vectors are particularly useful. The expression vectors are not particularly limited as long as the vectors express the antigen-binding molecules in vitro, in E. coli, in culture cells, or in a body of an organism. For example, pBEST vector (Promega) is preferred for in vitro expression; pET vector (Invitrogen) is preferred for E. coli; pME18S-FL3 vector (GenBank Accession No. AB009864) is preferred for culture cells; and pME18S vector (Mol Cell Biol. (1988) 8: 466-472) is preferred for bodies of organisms. In addition, EBNA1 protein may be co-expressed to increase the number of copies of the gene of interest. In this case, a vector that includes OriP as a initiation site of replication is used (Biotechnol Bioeng. 2001 Oct. 20; 75(2):197-203, Biotechnol Bioeng. 2005 Sep. 20; 91(6):670-7.) DNAs of the present invention can be inserted into the vectors by conventional methods, for example, by ligation using restriction enzyme sites (Current protocols in Molecular Biology, edit. Ausubel et al., (1987) Publish. John Wiley & Sons, Section 11.4-11.11).
The above host cells are not particularly limited, and various host cells may be used depending on the purpose. Examples of cells for expressing the antigen-binding molecules include bacterial cells (such as those of Streptococcus, Staphylococcus, E. coli, Streptomyces, and Bacillus subtilis), eukaryotic cells (such as those of yeast and Aspergillus), insect cells (such as Drosophila S2 and Spodoptera SF9), animal cells (such as CHO, COS, HeLa, C127, 3T3, BHK, HEK293, and Bowes melanoma cells), and plant cells. Vectors can be introduced into a host cell by known methods, for example, calcium phosphate precipitation methods, electroporation methods (Current protocols in Molecular Biology edit. Ausubel et al. (1987) Publish. John Wiley & Sons, Section 9.1-9.9), lipofection methods, and microinjection methods.
The host cells can be cultured by known methods. For example, when using animal cells as a host, DMEM, MEM, RPMI1640, or IMDM may be used as the culture medium. They may be used with serum supplements such as FBS or fetal calf serum (FCS). The cells may be cultured in serum-free cultures. The preferred pH is about 6 to 8 during the course of culturing. Incubation is carried out typically at 30 to 40 degrees C. for about 15 to 200 hours. Medium is exchanged, aerated, or agitated, as necessary.
Appropriate secretion signals may be incorporated to polypeptides of interest so that the antigen-binding molecules expressed in the host cell are secreted into the lumen of the endoplasmic reticulum, into the periplasmic space, or into the extracellular environment. These signals may be endogenous to the antigen-binding molecules of interest or may be heterologous signals.
On the other hand, for example, production systems using animals or plants may be used as systems for producing polypeptides in vivo. A polynucleotide of interest is introduced into an animal or plant and the polypeptide is produced in the body of the animal or plant, and then collected. The “hosts” of the present invention include such animals and plants.
The production system using animals include those using mammals or insects. It is possible to use mammals such as goats, pigs, sheep, mice, and bovines (Vicki Glaser SPECTRUM Biotechnology Applications (1993)). The mammals may be transgenic animals.
For example, a polynucleotide encoding an antigen-binding molecule of the present invention is prepared as a fusion gene with a gene encoding a polypeptide specifically produced in milk, such as the goat beta-casein. Next, goat embryos are injected with polynucleotide fragments containing the fusion gene, and then transplanted to female goats. Desired antigen-binding molecules can be obtained from milk produced by the transgenic goats, which are born from the goats that received the embryos, or from their offspring. Hormones may be administered as appropriate to increase the volume of milk containing the antigen-binding molecule produced by the transgenic goats (Ebert et al., Bio/Technology (1994) 12: 699-702).
Insects such as silkworms may be used to produce the antigen-binding molecules of the present invention. When silkworms are used, baculoviruses carrying a polynucleotide encoding an antigen-binding molecule of interest can be used to infect silkworms, and the antigen-binding molecule of interest can be obtained from their body fluids.
Furthermore, when plants are used to produce the antigen-binding molecules of the present invention, for example, tobacco may be used. When tobacco is used, a polynucleotide encoding an antigen-binding molecule of interest is inserted into a plant expression vector, for example, pMON 530, and then the vector is introduced into bacteria, such as Agrobacterium tumefaciens. The bacteria are then allowed to infect tobacco such as Nicotiana tabacum, and the desired antigen-binding molecules can be collected from their leaves (Ma et al., Eur. J. Immunol. (1994) 24: 131-138). Alternatively, it is possible to infect duckweed (Lemna minor) with similar bacteria. After cloning, the desired antigen-binding molecules can be obtained from the duckweed cells (Cox K M et al., Nat. Biotechnol. 2006 December; 24(12): 1591-1597).
The thus obtained antigen-binding molecules may be isolated from the inside or outside (such as the medium and milk) of host cells, and purified as substantially pure and homogenous antigen-binding molecules. The methods for isolating and purifying antigen-binding molecules are not particularly limited, and isolation and purification methods usually used for polypeptide purification can be used. Antigen-binding molecules may be isolated and purified, by appropriately selecting and combining, for example, chromatographic columns, filtration, ultrafiltration, salting out, solvent precipitation, solvent extraction, distillation, immunoprecipitation, SDS-polyacrylamide gel electrophoresis, isoelectric focusing, dialysis, and recrystallization.
Examples of chromatography techniques include, but are not limited to, affinity chromatography, ion exchange chromatography, hydrophobic chromatography, gel filtration, reverse-phase chromatography, and adsorption chromatography (Strategies for Protein Purification and Characterization: A Laboratory Course Manual. Ed Daniel R. Marshak et al., (1996) Cold Spring Harbor Laboratory Press). Such chromatographic methods can be conducted using liquid phase chromatography such as HPLC and FPLC. Columns used for affinity chromatography include, protein A columns and protein G columns. Columns using protein A include, for example, Hyper D, POROS, and Sepharose F. F. (Pharmacia).
If necessary, an antigen-binding molecule can be modified arbitrarily, and peptides can be partially deleted by allowing an appropriate protein modification enzyme to act before or after purification of the antigen-binding molecule. Such protein modification enzymes include, for example, trypsin, chymotrypsin, lysyl endopeptidases, protein kinases, and glucosidases.
While the present invention is herein described in detail and with reference to specific embodiments thereof, it is to be understood that the foregoing description is exemplary and explanatory in nature and is intended to illustrate the present invention and its preferred embodiments. Through routine experimentation, one skilled in the art will readily recognize that various changes and modifications can be made therein without departing from the spirit and scope of the present invention, the metes and bounds of which are defined by the appended claims.
Fc regions of the antigen-binding molecule (antibody) which interacts with FcRn (Nat Rev Immunol. 2007 September; 7(9):715-25) were engineered to have an improved binding affinity to FcRn at neutral pH in order to enhance the antigen elimination from plasma. The mechanism of antigen elimination from plasma by pH-dependent antigen binding antibody with improved binding affinity to FcRn at neutral pH in comparison to the conventional antibody is shown in
The Examples 1-17 of WO2011/122011 disclose mutations (amino acid substitutions) that improve the binding affinity to FcRn at neutral pH and describes Fc variants F1 to F599 (Table 16) that were generated with the focus on improving the binding affinity to FcRn at neutral pH of antibodies. However, for the pharmaceutical development of antibodies comprising such Fc variants, not only their pharmacological property (i.e improved FcRn binding) but also stability, purity and immunogenicity should be considered. Antibodies which exhibit poor stability and purity are not suitable as a drug, and poor immunogenicity would hinder their clinical development.
1-1. Design and Generation of Fc Variants with Improved Binding Affinity to hFcRn at Neutral pH
Various Fc variants with improved binding affinity to hFcRn at neutral pH while maintaining high stability, high purity and low immunogenicity risk were designed. Mutations (amino acid substitutions) introduced into Fc region of wild type IgG1 are shown for each Fc variants in Table 16 (IgG1-F1 to F1434). The amino acid substitutions were introduced into VH3-IgG1 (SEQ ID NO: 1) to generate Fc variants by the method known to those skilled in the art described in Reference Example 1 of WO2011/122011.
The variants (IgG1-F600 to IgG-F1434) each comprising a heavy chain prepared as described above and L(WT)-CK (SEQ ID NO: 2) were expressed and purified by the method known to those skilled in the art described in Reference Example 2 of WO2011/122011.
hFcRn binding affinity of new Fc variants prepared in Example 1 (F600-F1434) and previous Fc variants prepared in Example 1 of WO2011/122011 (F1-F599) was evaluated using Biacore T100 (GE Healthcare). For this purpose, human FcRn was prepared as described in Reference Example A2. An appropriate amount of protein L (ACTIGEN) was immobilized onto Sensor chip CM4 (GE Healthcare) by the amino coupling method, and the chip was allowed to capture an antibody of interest. Then, diluted FcRn solutions and running buffer (as a reference solution) were injected to allow human FcRn to interact with the antibody captured on the sensor chip. The running buffer used comprised 50 mmol/l sodium phosphate, 150 mmol/l NaCl, and 0.05% (w/v) Tween20 (pH 7.0). FcRn was diluted using each buffer. The chip was regenerated using 10 mmol/l glycine-HCl (pH 1.5). Assays were carried out exclusively at 25 degrees C. The association rate constant ka (1/Ms) and dissociation rate constant kd (1/s), both of which are kinetic parameters, were calculated based on the sensorgrams obtained in the assays, and KD (M) of each antibody for human FcRn was determined from these values. Each parameter was calculated using Biacore T100 Evaluation Software (GE Healthcare). The binding affinity of all Fc variants is shown in Table 16.
Stability of new Fc variants prepared in Example 1 (F600-F1434) and previous Fc variants prepared in Example 1 of WO2011/122011 (F1-F599) was evaluated using differential scanning fluorimetry (DSF). This method consists of measuring the fluorescence intensity of a polarity sensitive probe at gradually increasing temperatures, and obtaining the transition temperature of exposure of the hydrophobic regions of proteins. It is already reported that the transition temperatures acquired using DSF are in a good correlation with the melting temperatures acquired using differential scanning calorimetry (Journal of Pharmaceutical Science 2010; 4: 1707-1720). The SYPRO orange dye (Molecular Probes) was diluted into PBS (Sigma), and added to the protein solutions. Each sample was used with 20 microliter of the dyed solution. The fluorescence emission was collected at 555 nm with a fixed excitation wavelength at 470 nm. During the DSF experiment, the temperature was increased from 30 to 99 degrees C. and at 0.4 degrees C. increments with an equilibration time of 6 seconds at each temperature prior to measurement. The data were analyzed using Rotor-Gene Q Series Software (QIAGEN). The temperature of the fluorescence transition is defined as the melting temperature (Tm). Tm values of the Fc variants F1-F1434 are shown in Table 16.
High molecular weight species percentage (HMW (%)) of the new Fc variants prepared in Example 1 (F600-F1434) and previous Fc variants prepared in Example 1 of WO2011/122011 (F1-F599) was evaluated using size exclusion chromatography (SEC). SEC was performed in ACQUITY UPLC H-Class system (waters). The antibodies were injected onto a BEH200 SEC column (1.7 micrometer, 4.6×150 mm, waters). The mobile phase was 0.05 M sodium phosphate, 0.3 M sodium chloride (pH7.0, Isekyu), running isocratically at a flow rate of 0.3 mL/min. Eluted protein was detected by UV absorbance at 215 nm. The data were analyzed using Empower2 (waters). Peaks eluting earlier than the antibody monomer peak were recorded in the HMW components percentile. The HMW (%) of all Fc variants (F1-F1434) are shown in Table 16.
Clinical utility and efficacy of the therapeutic antibodies can be limited by the production of anti-drug antibodies (ADAs), since ADA can influence their efficacy and pharmacokinetics and sometimes lead to serious side effects. Although many factors influence the immunogenicity of therapeutic antibodies, a number of reports describe the importance of effector T-cell epitopes present in the therapeutic protein.
In silico tools to predict T-cell epitopes, such as Epibase (Lonza), iTope/TCED (Antitope) and EpiMatrix (EpiVax) have been developed. By using these in silico tools, the presence of T-cell epitope in each amino acid sequence can be predicted (Expert Opin Biol Ther. 2007 March; 7(3):405-18.), allowing the evaluation of potential immunogenicity of the Fc variants. Epibase Light (Lonza) was used to evaluate the potential immunogenicity of the Fc variants.
Epibase Light (Lonza) is an in silico tool to calculate the binding affinity of 9-mer peptide to major DRB1 alleles using FASTER algorism (Expert Opin Biol Ther. 2007 March; 7(3):405-18.). Epibase Light (Lonza) identifies T-cell epitopes with strong binding and medium binding to MHC class II. In silico immunogenicity score for each Fc variants was calculated using the following formula incorporated in Epibase Light (Lonza) system. Immunogenicity score=Sum ((each DRB1 allotype population frequency)×(number of critical epitopes)).
For DRB1 allotype population frequency used in the formula, following DRB1 allotype population frequency based on Caucasian population was used.
The total number of any strong and medium binding epitopes identified in constant region (CH1-hinge-CH2-CH3) of the variants by FASTER algorism was used as number of critical epitopes in the formula. Filtered epitopes are those with human antibody germline sequence or junction regions between variable region and constant region, and only non-filtered epitopes are considered (counted as critical epitope) in the immunogenicity score calculation.
Immunogenicity score of amino acid sequence of new Fc variants described in Example 1 (F600-F1434) and previous Fc variants described in Example 1 of WO2011/122011 (F1-F599) was calculated using above described Epibase Light (Lonza) system. Immunogenicity score of all Fc variants (F1-F1434) are shown in Table 16.
2-1. Analysis of Previous and New Fc Variants by Plotting Tm, HMW (%) and Immunogenicity Score Against hFcRn Binding Affinity
hFcRn binding affinity and Tm of previous Fc variants (F1-F599) described in Example 1 of WO2011/122011 and new Fc variants (F600-F1052) generated and evaluated in Example 1 were plotted and are shown in
The new Fc variants (F600-F1052) and previous Fc variants (F1-F599) variants having Ser239Lys or Asp270Phe mutation were deleted from the plots. Since Ser239Lys and Asp270Phe mutation improved the stability (Tm) while it did not improve FcRn binding affinity and reduced the binding affinity to all human Fc gamma receptors, in the following detailed analysis of Group 1-4, stability of Fc variants should be compared within the variants that do not have Ser239Lys nor Asp270Phe mutation.
In addition, new Fc variants (F600-F1052) and previous Fc variants (F1-F599) variants having Pro257Xxx (Xxx is Ala or Val or Ile or Leu or Thr) or Met252Trp mutation were deleted from the plots although these variants improve FcRn binding affinity. Pro257Xxx and Met252Trp mutation did not exhibit significant reduction in Tm suggesting that variants with Pro257Xxx and Met252Trp mutation have high stability. Nevertheless, these variants having Pro257Xxx or Met252Trp mutations showed significant aggregation and precipitation during an accelerated stability study or when stored refrigerated. Due to their detrimental stability, Fc variants with Pro257Xxx and Met252Trp mutation are not acceptable for pharmaceutical development and therefore, in the following detailed analysis of Group 1-4, such Fc variants should be deleted from the plots.
2-2. Detailed Analysis of Group 1 (Binding Affinity to hFcRn Stronger than 15 nM)
New Fc variants (F600-F1052) generated and evaluated in Example 1, and previous Fc variants (F1-F599) described in Example 1 of WO2011/122011, with binding affinity to hFcRn stronger than 15 nM (described as Group 1 hereafter), were analyzed in detail by plotting hFcRn binding affinity in X-axis and Tm, HMW (%) and immunogenicity score in Y-axis.
Detail analysis of Group 1 by plotting hFcRn binding affinity (KD stronger than 15 nM) in X-axis and Tm, HMW (%) and immunogenicity score in Y-axis are shown respectively in
As for developability criteria of Fc variants in Group 1, Tm criteria was set as higher than 57.5 degrees C., HMW (%) criteria was set as lower than 2%, and immunogenicity score was set as lower than 500.
Fc variants in Group 1 which satisfies all the developability criteria (Tm higher than 57.5 degrees C., HMW (%) lower than 2%, and immunogenicity score lower than 500) are shown in Table 17.
None of the previous Fc variants (F1-F599) had an affinity stronger than 15 nM, whereas the several new Fc variants generated in EXAMPLE 1 were stronger than 15 nM and met all the developability criteria. Such Group 1 new Fc variants described in Table 17 are extremely valuable for Fc domain to enable very rapid and extensive antigen elimination from plasma especially when used in combination with pH-dependent antigen-binding domain.
2-3. Detailed Analysis of Group 2 (Binding Affinity to hFcRn Between 15 nM and 50 nM)
New Fc variants (F600-F1052) generated and evaluated in Example 1, and previous Fc variants (F1-F599) described in Example 1 of WO2011/122011, with binding affinity to hFcRn between 15 nM and 50 nM (hereafter called “Group 2”), were analyzed in detail by plotting hFcRn binding affinity on the X-axis and Tm, HMW (%) and immunogenicity score on Y-axis.
Detailed analysis of Group 2 by plotting hFcRn binding affinity (KD between 15 nM and 50 nM) on the x-axis, and Tm, HMW (%) or immunogenicity score on the Y-axis are shown in
As for developability criteria of Fc variants in Group 2, Tm criteria was set as higher than 60 degrees C., HMW (%) criteria was set as lower than 2%, and immunogenicity score was set as lower than 500.
Fc variants in Group 2 which satisfies all the developability criteria (Tm higher than 60 degrees C., HMW (%) lower than 2%, and immunogenicity score lower than 500) are shown in Table 18.
None of the previous Fc variants (F1-F599) satisfied all the developability criteria, but several of the new Fc variants generated in Example 1 met all. Such Fc variants of Group 2 which meet the developability criteria are extremely valuable to enable rapid and extensive antigen elimination from plasma especially when used in combination with pH-dependent antigen-binding domain.
2-4. Detailed Analysis of Group 3 (Binding Affinity to hFcRn Between 50 nM and 150 nM)
New Fc variants (F600-F1052) generated and evaluated in Example 1, and previous Fc variants (F1-F599) described in Example 1 of WO2011/122011, with binding affinity to hFcRn between 50 nM and 150 nM (called hereinafter “Group 3”), were analyzed in detail by plotting hFcRn binding affinity on the X-axis and Tm, HMW (%) and immunogenicity score on the Y-axis.
Detail analysis of Group 3 by plotting hFcRn binding affinity (KD between 50 nM and 150 nM) in X-axis, and Tm, HMW (%) or immunogenicity score on Y-axis are shown in
As for developability criteria of Fc variants in Group 3, Tm criteria was set as higher than 63.0 degrees C., HMW (%) criteria was set as lower than 2%, and immunogenicity score was set as lower than 250.
Fc variants in Group 3 which satisfies all the developability criteria (Tm higher than 63.0 degrees C., HMW (%) lower than 2%, and immunogenicity score lower than 250) are shown in Table 19.
None of the previous Fc variants (F1-F599) satisfied all the developability criteria, whereas the several new Fc variants generated in Example 1 met all. Such new Fc variants of Group 3 which meet all developability criteria are extremely valuable to enable moderate and sustained antigen elimination from plasma especially used in combination with pH-dependent antigen-binding domain.
2-5. Detailed Analysis of Group 4 (Binding Affinity to hFcRn Between 150 nM and 700 nM)
New Fc variants (F600-F1052) generated and evaluated in Example 1, and previous Fc variants (F1-F599) described in Example 1 of WO2011/122011, with binding affinity to hFcRn between 150 nM and 700 nM (called hereinafter “Group 4”), were analyzed in detail by plotting hFcRn binding affinity on X-axis and Tm, HMW (%) and immunogenicity score on Y-axis.
Detail analysis of Group 4 by plotting hFcRn binding affinity (KD between 150 nM and 700 nM) on X-axis, and Tm, HMW (%) or immunogenicity score on Y-axis are shown in
As for developability criteria of Fc variants in Group 4, Tm criteria was set as higher than 66.5 degrees C., HMW (%) criteria was set as lower than 2%, and immunogenicity score was set as lower than 250.
Fc variants in Group 4 which satisfies all the developability criteria (Tm higher than 66.5 degrees C., HMW (%) lower than 2%, and immunogenicity score lower than 250) are shown in Table 20.
None of the previous Fc variants (F1-F599) satisfied all the developability criteria, whereas the several new Fc variants generated in Example 1 met them all. Such new Fc variants of Group 4 which meet all developability criteria are extremely valuable to enable moderate and sustained antigen elimination from plasma especially used in combination with pH-dependent antigen-binding domain.
In summary, new Fc variants described in Table 17 to 20 have high Tm, low HMW (%), and low immunogenicity score which are suitable for pharmaceutical development of antigen-binding molecule capable of removing antigen from the plasma.
pH-dependent anti-human IL6 receptor IgG1 antibody, Fv-4-IgG1 comprising VH3-IgG1 (SEQ ID NO: 1) and VL3-CK (SEQ ID NO: 3), previous Fc variant Fv-4-F11 comprising VH3-F11 (SEQ ID NO: 4) and VL3-CK (SEQ ID NO: 3), new Fc variants, Fv-4-F652 comprising VH3-F652 (SEQ ID NO: 5) and VL3-CK (SEQ ID NO: 3), and Fv-4-F890 comprising VH3-F890 (SEQ ID NO: 6) and VL3-CK (SEQ ID NO: 3), and Fv-4-F946 comprising VH3-F946 (SEQ ID NO: 7) and VL3-CK (SEQ ID NO: 3) were expressed and purified by the method known to those skilled in the art described in Reference Example 2 of WO2011/122011.
In vivo antigen elimination study of Fv-4-IgG1, Fv-4-F11, Fv-4-F652, Fv-4-F890 and Fv-4-F946 were performed in human IL-6 receptor steady-state infusion model using human FcRn transgenic.
An in vivo test was conducted by steady-state infusion model using human FcRn transgenic mouse line 32. An infusion pump (MINI-OSMOTIC PUMP MODEL 2004; alzet) containing soluble human IL-6 receptor was implanted under the skin on the back of human FcRn transgenic mouse line 32 (B6.mFcRn−/−.hFcRn Tg line 32+/+ mouse (B6.mFcRn−/− hFCRN Tg32 B6.Cg-Fcgrt<tm1Dcr> Tg(FCGRT)32Dcr), Jackson Laboratories; Methods Mol Biol. (2010) 602: 93-104) to prepare model animals in which the plasma concentration of soluble human IL-6 receptor was kept constant. Anti-human IL-6 receptor antibodies were administered to the model animals to assess the in vivo dynamics after administration of soluble human IL-6 receptor. Monoclonal anti-mouse CD4 antibody (in house) was administered at 20 mg/kg before implanting infusion pump, and 7 and 17 days after antibody administration into the caudal vein to suppress the production of neutralizing antibody against soluble human IL-6 receptor. Then, an infusion pump containing 92.8 microgram/ml soluble human IL-6 receptor was implanted under the skin on the back of the mice. Three days after implantation of an infusion pump, anti-human IL-6 receptor antibodies were administered once into the caudal vein. In study 1, Fv-4-IgG1, Fv-4-F652, Fv-4-F890 and Fv-4-F946 were administered at as dosage of 1 mg/kg together with approximately 1 g/kg Sanglopor (CSL Behring), and in study 2, Fv-4-IgG1, Fv-4-F11 and Fv-4-F652 were administered at 1 mg/kg. In both studies, no antibody was administered to the control group (no antibody injection). Blood was collected at appropriate time points after the administration of the anti-human IL-6 receptor antibody. The collected blood was immediately centrifuged at 15,000 rpm and 4 degrees C. for 15 minutes to separate plasma. The separated plasma was stored in a refrigerator at −20 degrees C. or below before the assay.
The concentration of anti-human IL-6 receptor antibody in mouse plasma was measured by ELISA. Anti-human IgG (gamma-chain specific) F(ab′)2 antibody fragment (Sigma) was dispensed onto a Nunc-ImmunoPlate MaxiSorp (Nalge Nunc International) and allowed to stand overnight at 4 degrees C. to prepare anti-human IgG-immobilized plates. Calibration curve samples having plasma concentrations of 0.8, 0.4, 0.2, 0.1, 0.05, 0.025, and 0.0125 microgram/ml, and mouse plasma samples diluted 100-fold or more were prepared. 200 microliter of 20 ng/ml hsIL-6R were added to 100 microliter of the calibration curve samples and plasma samples, and then the samples were allowed to stand for one hour at room temperature. Subsequently, the samples were dispensed onto the anti-human IgG-immobilized plates, and allowed to stand for one hour at room temperature. Then, Biotinylated Anti-Human IL-6R Antibody (R&D) was added to react for one hour at room temperature. Subsequently, Streptavidin-PolyHRP80 (Stereospecific Detection Technologies) was added to react for one hour at room temperature, and chromogenic reaction was carried out using TMP One Component HRP Microwell Substrate (BioFX Laboratories) as a substrate. After stopping the reaction with 1 N sulfuric acid (Showa Chemical), the absorbance at 450 nm was measured by a microplate reader. The concentration in mouse plasma was calculated from the absorbance of the calibration curve using the analytical software SOFTmax PRO (Molecular Devices).
3-4. Measurement of hsIL-6R Plasma Concentration by Electrochemiluminescence Assay
The concentration of hsIL-6R in mouse plasma was measured by electrochemiluminescence. hsIL-6R calibration curve samples adjusted to concentrations of 2,000, 1,000, 500, 250, 125, 62.5, and 31.25 pg/ml, and mouse plasma samples diluted 50-fold or more were prepared. The samples were mixed with a solution of Monoclonal Anti-human IL-6R Antibody (R&D) ruthenium-labeled with Sulfo-Tag NHS Ester (Meso Scale Discovery), Biotinylated Anti-human IL-6R Antibody (R&D, Systems Inc., USA), and tocilizumab (Chugai Pharmaceutical Co., Ltd.)), and then allowed to react overnight at 37 degrees C. The final concentration of tocilizumab as an anti-human IL-6 receptor antibody was 333 microgram/ml, which is in excess of the concentration of anti-human IL-6 receptor antibody contained in the samples, for the purpose of binding nearly all of the hsIL-6R molecules in the samples to tocilizumab. Subsequently, the samples were dispensed into an MA400 PR Streptavidin Plate (Meso Scale Discovery), and allowed to react for one hour at room temperature, and washing was performed. Immediately after Read Buffer T (×4) (Meso Scale Discovery) was dispensed, the measurement was performed by the Sector PR 400 Reader (Meso Scale Discovery). The hsIL-6R concentration was calculated based on the response of the calibration curve using the analytical software SOFTmax PRO (Molecular Devices).
Therefore, this study demonstrated that Fv-4-F652 and Fv-4-F890 were able to selectively eliminate soluble antigen from plasma while maintaining antibody pharmacokinetics comparable to that of Fv-4-IgG1. Fv-4-F890 belongs to Group 3, and this study demonstrated that Fc variants in Group 3 can reduce then plasma antigen concentration by approximately 10-fold while maintaining the antibody pharmacokinetic comparable to IgG1. This means that applying Group 3 Fc variant to pH-dependent antigen binding IgG1 antibody can lower the antibody dosage by 10-fold. Such reduction in antibody dosage by Group 3 Fc variant is especially meaningful when antibody dosage needs to be reduced, and simultaneously requires infrequent dosing.
On the other hand, Fv-4-F946 demonstrated 100-fold reduction of plasma hsIL-6R concentration compared to Fv-4-IgG1, and antibody clearance of Fv-4-F946 was larger than Fv-4-IgG1. Fv-4-F946 belongs to Group 2, and this study demonstrated that Fc variants in Group 2 can reduce the plasma antigen concentration by approximately 100-fold although the antibody clearance is larger than IgG1. This means that applying Group 2 Fc variant to pH-dependent antigen binding IgG1 antibody can reduce the total plasma antigen concentration by approximately 100-fold. In case the target plasma antigen concentration is too high to neutralize by realistic antibody dosage (i.e 100 mg/kg), 100-fold reduction of total antigen concentration regardless of the increase of antigen clearance by Group 2 Fc variant means that target antigen can be neutralized by less than 10 mg/kg, which is a realistic antibody dosage.
hFcRn binding affinity of Fv-4-F652 and Fv-4-F890 were measured in multiplicates, and affinity against hFcRn was 2.4E-07 M (n=7) for F652, and 1.1E-07 M (n=12) for F890. Previous studies described in Example 1 of WO2011/122011 revealed that the extent of antigen elimination and antibody clearance correlated with binding affinity to FcRn at neutral pH. As shown in
In order to identify which residue contributed to the enhanced antigen sweeping effect of F652, study 2 was performed using F11 (Met252Tyr, Asn434Tyr double mutant) and F652 (Pro238Asp, Met252Tyr, Asn434Tyr triple mutant). Affinity against hFcRn was 3.1E-07 M (n=12) for F11, which was comparable to the affinity measured for F652.
Therefore, this study demonstrated that Pro238Asp mutation were able to enhance antigen elimination plasma while maintaining antibody pharmacokinetics comparable to Fv-4-IgG1. Therefore, Pro238Asp mutation is extremely valuable for enhancing antigen elimination by pH-dependent antigen binding antibody.
Clinical utility and efficacy of the therapeutic antibodies can be limited by the production of anti-drug antibodies (ADAs), since ADA can influence their efficacy and pharmacokinetics and sometimes lead to serious side effects. Many factors influence the immunogenicity of therapeutic antibodies, and the presence of effector T-cell epitopes is one of the factors. In addition, presence of pre-existing antibodies against therapeutic antibody can also be problematic from the point of ADA. Especially in case of therapeutic antibody for patients with autoimmune disease such as rheumatoid arthritis, rheumatoid factor, an autoantibody against human IgG, could be an issue of pre-existing antibody. Recently, it was reported that humanized anti-CD4 IgG1 antibody with Asn434H is mutation elicited significant rheumatoid factor binding (Clin Pharmacol Ther. 2011 February; 89(2):283-90). Detail study have confirmed that Asn434H is mutation in the human IgG1 increased the binding of rheumatoid factor to the Fc region of the antibody compared to the parent human IgG1.
Rheumatoid factor is a polyclonal autoantibody against human IgG, and their epitope in human IgG varies among the clone, but their epitope seems to be located in the CH2/CH3 interface region as well as CH3 domain which could overlap with the FcRn binding epitope. Therefore, mutations to increase the binding affinity to FcRn might also increase the binding affinity to specific clone of rheumatoid factor.
Previous studies have demonstrated that Fc-engineering to increase the binding affinity to FcRn at acidic pH improved the endosomal recycling efficiency and prolonged the pharmacokinetics of the antibody. For example, M252Y/S254T/T256E (YTE) variant (J Biol Chem 2006 281:23514-23524.), M428L/N434S (LS) variant (Nat Biotechnol, 2010 28:157-159.) and N434H variant (Clinical Pharmacology & Therapeutics (2011) 89(2):283-290.) showed improvement in half-life relative to native IgG1.
To achieve antigen elimination from plasma, Fc regions of the antigen-binding molecule (antibody) which interacts with FcRn (Nat Rev Immunol. 2007 September; 7(9):715-25) was engineered to have improved binding affinity to FcRn at neutral pH, such engineered Fc variants include F11 variant, F68 variant, F890 variant and F947 variant. The mechanism of antigen elimination from plasma by pH-dependent antigen binding antibody with improved binding affinity to FcRn at neutral pH in comparison to the conventional antibody is shown in
Such Fc variant with improved FcRn-binding (either at pH 6.0 and/or neutral pH) could exhibit increased binding to rheumatoid factor as in the case of previously reported Asn434H is mutation. Therefore, we tested whether these FcRn binding improved Fc variants would exhibit increased binding to rheumatoid factor. Variant antibodies used in the following study were Fv-4-hIgG1, Fv-4-YTE, Fv-4-LS, Fv-4-N434H, Fv-4-F11, Fv-4-F68, Fv-4-890 and Fv-4-F947.
Binding assay against rheumatoid factor was performed by Electrochemiluminescence (ECL) at pH7.4. The assays were performed with the serum of 15 or 30 individual RA patients (Proteogenex). 50-fold diluted serum samples, Biotin labeled test antibody (1 microgram/mL) and SULFO-TAG NHS Ester (Meso Scale Discovery) labeled test antibody (1 microgram/mL) were mixed and incubated for 3 hr at room temperature. Then, the mixtures were added to Streptavidin coated MULTI-ARRAY 96 well plates (Meso Scale Discovery), and the plates were incubated for 2 hr at room temperature and washed. After Read Buffer T (×4) (Meso Scale Discovery) was added to each well, plates were immediately set on the SECTOR imager 2400 Reader (Meso Scale Discovery) and the chemiluminescence was measured.
Results of this study are shown in
Therefore, in the next study, we have generated panels of variants that could potentially reduce the polyclonal rheumatoid factor binding while maintaining FcRn binding capability.
In order to generate the variants with reduced polyclonal rheumatoid factor binding while maintaining FcRn binding capability, mutations were rationally introduced to the surface residues near the CH2/CH3 interface which was assumed not to interfere with human FcRn/human IgG interaction.
Fv-4-F890 was selected as parent Fc variant, and single mutation and combined Fc variants of single mutation were introduced into Fv-4-F890. The novel Fc variants F1058 to F1073, F1107 to F1114, F1104 to F1106, and F1230 to F1232 described in Table 21 were generated. In addition, Fv-4-F947 was selected as parent Fc variant and same single and combined mutations were introduced. The novel Fc variants F1119-F1124 described in Table 21 were generated. First the variants were evaluated for their binding affinity to human FcRn at pH7.0. Results are also described in Table 21. Compared to either parent Fv-4-F890 or Fv-4-F947, these variants did not show significant reduction in binding affinity against human FcRn, demonstrating that these mutations did not affect human FcRn binding.
Then we performed rheumatoid factor binding study at pH 7 for the variants in Table 21. Results of this study are shown in
Furthermore, compared to single mutated Fc F1070 (Q438R) or F1072 (S440E), double mutated Fc F1106 (Q438R/S440E) showed significant reduction in rheumatoid factor binding. Likewise, double mutated Fc F1230 (Q438R/S440D), F1231 (Q438K/S440E) and F1232 (Q438K/S440D) also showed additional reduction in rheumatoid factor binding by combination of mutations. Meanwhile, F1104 (V422E/S424R) or F1105 (V422S/S424R) did not show any combination effect.
In addition, with Fv-4-F939 selected as parent Fc variant, other mutations for increasing FcRn binding (S254T or T256E) and for reducing rheumatoid factor binding (H433D) were evaluated. Novel Fc variants (F1291, F1268, F1269, F1243, F1245, F1321, F1340 and F1323) described in Table 22 were generated. First, the variants were evaluated for their binding affinity to human FcRn at pH7.0. Results are also described in Table 22.
Then we performed rheumatoid factor binding study for these variants as described above. Results of this study are shown in
Introduction of additional N-glycosylation near the rheumatoid factor binding epitope may also abrogate rheumatoid factor binding, due to steric hindrance with bulky N-glycosylation. Mutation can be selected from the point so that the mutation introduces N-glycosylation sequence (Asn-Xxx-Ser/Thr) while maintaining FcRn binding. In order to introduce additional N-glycosylation sequence into Fc region, single or double mutation(s) were introduced into Fv-4-F11. Novel Fc variants (F1077-F1083, F1094-F1097) described in Table 23 were generated. The variants were evaluated for their binding affinity to human FcRn at pH7.0 and the presence of additional glycosylation by SDS-Page. Results are described in Table 23. F1077 (K248N), F1080 (S424N), F1081 (Y436N/Q438T) and F1082 (Q438N) were found to have additional glycosylation, and especially F1080 (S424N) maintained binding affinity against human FcRn.
Therefore, in the next study, S424N mutation was introduced into Fv-4-F890, Fv-4-F1115 described in Table 24 was generated and evaluated for their binding affinity to human FcRn at pH7.0. Results are also described in Table 24.
Then we performed rheumatoid factor binding study for these variants as described above. Result of this study is shown in
In order to reduce rheumatoid factor binding of Fv-4-YTE, Fv-4-N434H and Fv-4-LS variants, which improves FcRn binding at acidic pH and prolongs antibody pharmacokinetics, Q438R/S440E mutations or S424N mutation were introduced into these variants. Novel Fc variants (F1166, F1167, F1172, F1173, F1170 and F1171) described in Table 25 were generated. First the variants were evaluated for their binding affinity to human FcRn at pH6.0. Results are also described in Table 25.
Then we performed rheumatoid factor binding study for these variants (Fv-4-F1166, F1167, F1172, F1173, F1170 and F1171) as described above. Result of this study is shown in
Novel single mutations were introduced into Fv-4-LS, Fc variants (Fv-4-F1380 to Fv-4-F1392) described in Table 26 were generated.
Then we performed rheumatoid factor binding study for the variants which maintains FcRn binding at pH6.0 (Fv-4-F1380, F1384-F1386, F1388 and F1389). Result of this study is shown in
Therefore, mutation such as Pro387Arg, Val422Glu, Val422Arg, Val422Ser, Val422Asp, Val422Lys, Val422Thr, Val422Gln, Ser424Glu, Ser424Arg, Ser424Lys, Ser424Asn, Ser426Asp, Ser426Ala, Ser426Gln, Ser426Tyr, His433Asp, Tyr436Thr, Gln438Glu, Gln438Arg, Gln438Ser, Gln438Lys, Ser440Glu, Ser440Asp, Ser440Gln (positions are given in EU numbering) are extremely useful for reducing the immunogenicity of antigen-binding molecule containing FcRn binding increased Fc region (for example F1-F1434) such as pH-dependent antigen binding antibody with improved binding affinity to FcRn at neutral pH which is capable of eliminating antigen from plasma and antibody with improved binding affinity to FcRn at acidic pH which is capable of improving antibody pharmacokinetics.
Mutation sites other than EU387, EU422, EU424, EU426, EU433, EU436, EU438 and EU440 for reducing the binding of rheumatoid factor without affecting human FcRn binding could be selected from 248-257, 305-314, 342-352, 380-386, 388, 414-421, 423, 425-437, 439, and 441-444 in EU numbering.
Novel Fc variants (F939, F1378, F1379, F1262, F1138, F1344, F1349, F1350, F1351, F1261, F1263, F1305, F1306, F1268, F1269, F1413, F1416, F1419, F1420, F1370, F1371, F1599, F1600, F1566, F1448, F1601-F1603, F1531, F1604, F1605, F1586, F1592, F1610-F1615, F1567, F1572, F1576, F1578, F1579, F1641-F1655, F1329, F1331) described in Table 27 were generated. First the variants were evaluated for their binding affinity to human FcRn at pH7.0. Results are also described in Table 27.
Then we performed rheumatoid factor binding study at pH 7.4 for the variants in Table 27. Results of this study are shown in
Double mutations for decreasing rheumatoid factor binding (Q438R/S440E, Q438R/S440D, Q438K/S440E and Q438K/S440D) showed significant reduction in rheumatoid factor binding to other mutations for increasing FcRn binding at neutral pH.
5-1. Reduction of Rheumatoid Factor Binding of Novel Fc Variants with Improved Binding to Human FcRn at Acidic pH
Novel Fc variants (F1718-F1721, F1671, F1670, F1711-F1713, F1722-F1725, F1675, F1714-F1717, F1683, F1756-F1759, F1681, F1749-F1751, F1760-F1763, F1752-F1755, F1685) described in Table 28 were generated. First the variants were evaluated for their binding affinity to human FcRn at pH6.0. Results are also described in Table 28.
Then we performed rheumatoid factor binding study at pH 7.4 for the variants in Table 28. Results of this study are shown in
Double mutations for decreasing rheumatoid factor binding (Q438R/S440E, Q438R/S440D, Q438K/S440E and Q438K/S440D) showed significant reduction in rheumatoid factor binding to other mutations for increasing FcRn binding at acidic pH.
pH-dependent anti-human IL6 receptor IgG1 antibody, Fv-4-IgG1 comprising VH3-IgG1 (SEQ ID NO: 1) and VL3-CK (SEQ ID NO: 3), new Fc variants, Fv-4-F1243 comprising VH3-F1243 (SEQ ID NO: 8) and VL3-CK (SEQ ID NO: 3), and Fv-4-F1245 comprising VH3-F1245 (SEQ ID NO: 9) and VL3-CK (SEQ ID NO: 3) were expressed and purified by the method known to those skilled in the art described in Example 2 of WO2011/122011.
As described in Example 4, Fv-4-F1243 and Fv-4-F1245 have novel Fc region with improved binding affinity to human FcRn at neutral pH, but significantly reduced binding to rheumatoid factor. In order to evaluate antigen elimination effect of these variants, an in vivo study of Fv-4-IgG1, Fv-4-F1243 and Fv-4-F1245 was performed in a human IL-6 receptor steady-state infusion model using human FcRn transgenic mice.
An in vivo test was conducted by steady-state infusion model using human FcRn transgenic mouse line 32 by the same methods described in Example 13 of WO2011/122011.
pH-dependent anti-human IL6 receptor IgG1 antibody, Fv-4-IgG1 comprising VH3-IgG1 (SEQ ID NO: 1) and VL3-CK (SEQ ID NO: 3), a new Fc variant, Fv-4-F1389 comprising VH3-F1389 (SEQ ID NO: 10) and VL3-CK (SEQ ID NO: 3), were expressed and purified by the method known to those skilled in the art described in Reference Example 2 of WO2011/122011.
As described in Example 4 and 5, Fv-4-F1389 has a novel Fc region with improved binding affinity to human FcRn at acidic pH, but significantly reduced binding to rheumatoid factor. In order to evaluate the pharmacokinetics of this variant, an in vivo study of Fv-4-IgG1 and Fv-4-F1389 was performed using human FcRn transgenic mice.
An in vivo test was conducted using human FcRn transgenic mouse line 32 by the same methods described in Example 13 of WO2011/122011.
8-1. Preparation of Human IgA (hIgA)
Human IgA (hereinafter also abbreviated as “hIgA”) was prepared as an antigen by using the following recombinant techniques. hIgA (the variable region is derived from an anti-human IL-6 Receptor antibody) was expressed by culturing host cells carrying recombinant vectors inserted with H (WT)-IgA1 (SEQ ID NO: 12) and L (WT) (SEQ ID NO: 13) and purified by a method known to those skilled in the art using ion-exchange chromatography and gel filtration chromatography.
8-2. Expression and Purification of Antibodies that Bind to hIgA
GA2-IgG1 (heavy chain SEQ ID NO: 14; light chain SEQ ID NO: 15) is an antibody that bind to hIgA. The DNA sequences encoding heavy chain of GA2-IgG1 (SEQ ID NO: 14) and light chain of GA2-IgG1 (SEQ ID NO: 15) were inserted into animal cell expression plasmids by a method known to those skilled in the art. The antibody was expressed by the method described below. Cells of human fetal kidney cell-derived line FreeStyle 293-F (Invitrogen) were suspended in FreeStyle 293 Expression Medium (Invitrogen). The cell suspension was seeded into a 6-well plate (3 mL/well) at a cell density of 1.33×106 cells/ml. Then, the constructed plasmids were introduced into the cells by a lipofection method. The cells were cultured for four days in a CO2 incubator (37 degrees C., 8% CO2, 90 rpm). The antibodies were purified from the isolated culture supernatants by a method known to those skilled in the art using rProtein A Sepharose™ Fast Flow (Amersham Biosciences). The absorbance (wavelength: 280 nm) of the purified antibody solutions was measured using a spectrophotometer. The antibody concentrations were determined from the measured values using the absorption coefficient calculated by the PACE method (Protein Science (1995) 4, 2411-2423).
8-3. Assessment of Obtained Antibodies for Calcium-Dependent hIgA-Binding Activity
The antibodies isolated as described in 8-2 were assessed for their hIgA-binding activity (dissociation constant KD (M)) using Biacore T200 (GE Healthcare). Running buffers used in the measurement were 0.05% tween20/20 mmol/L ACES/150 mmol/L NaCl (pH 7.4 or 5.8) containing 3 microM or 1.2 mM CaCl2.
The antibody was allowed to bind to Sensor chip CM5 (GE Healthcare) immobilized with a suitable amount of recombinant Protein A/G (Thermo Scientific) by the amino coupling method. Then, an appropriate concentration of hIgA (described in 8-1) was injected as an analyte to allow interaction with the antibody on the sensor chip. The measurement was carried out at 37 degrees C. After the measurement, 10 mmol/L glycine-HCl (pH 1.5) was injected to regenerate the sensor chip. The dissociation constant KD (M) was calculated from the measurement result by curve fitting analysis and equilibrium parameter analysis using Biacore T200 Evaluation Software (GE Healthcare). The result and obtained sensorgrams are shown in Table 29 and
Next, to evaluate the effect of FcRn binding on antigen (hIgA) elimination from plasma, GA2-F760 (heavy chain SEQ ID NO: 16; light chain SEQ ID NO: 15) was constructed by introducing amino acid substitutions L235R and S239K into GA2-IgG1 to eliminate binding to FcgammaR. Furthermore GA2-F1331 (heavy chain SEQ ID NO: 17; light chain SEQ ID NO: 15) was constructed by introducing amino acid substitution G236R, M252Y, S254T, T256E, N434Y, Y436V, Q438R and S440E into GA2-F760, which binds to FcRn stronger than GA2-F760 at pH 7.4. The modified antibodies were expressed by the method described above using animal expression plasmids inserted with DNA sequences encoding GA2-F1331 (heavy chain SEQ ID NO: 17; light chain SEQ ID NO: 15) and GA2-F760 (heavy chain SEQ ID NO: 16; light chain SEQ ID NO: 15) by a method known to those skilled in the art. The antibody concentrations were determined after purification. GA2-F760 was assessed for its binding to various mouse FcgammaR (mFcgammaRI, mFcgammaRII, mFcgammaRIII, and mFcgammaRIV). The result showed that GA2-F760 did not bind to any of the receptors.
Pharmacokinetics of hIgA and anti-hIgA antibody was assessed after administration of hIgA (human IgA; prepared as described in Example 8) alone or in combination with an anti-hIgA antibody to human FcRn transgenic mice (B6.mFcRn−/−.hFcRn Tg line 32+/+ mouse, Jackson Laboratories; Methods Mol. Biol. (2010) 602: 93-104). A mixture of hIgA and anti-hIgA antibody was administered once at a dose of 10 mL/kg via the caudal vein. GA2-F760 and GA2-F1331 described above were the anti-hIgA antibodies that were used.
In every mixture, the hIgA concentration was 80 microg/mL and the anti-hIgA antibody concentration was 2.69 mg/mL. Under the conditions described above, the majority of hIgA is predicted to bind to the antibody since the anti-hIgA antibody is present in sufficient excess over hIgA. Blood was collected from the mice fifteen minutes, one hour, two hours, seven hours, one day, three days, seven days and fourteen days after administration. The collected blood was immediately centrifuged for 15 minutes at 12,000 rpm and 4 degrees C. to obtain the plasma. The separated plasma was stored in a freezer at −20 degrees C. or below until measurement.
The anti-hIgA antibody concentrations in mouse plasma were determined by ELISA. First, Anti-Human IgG-immobilized plates were prepared by aliquoting Anti-Human IgG (gamma-chain specific) F(ab′)2 Fragment Antibody (SIGMA) to each well of Nunc-Immuno Plate, MaxiSorp (Nalge nunc International) and allowing the plates to stand at 4 degrees C. overnight. Anti-hIgA antibody standard curve samples prepared as standard solutions at plasma concentrations of 0.5, 0.25, 0.125, 0.0625, 0.03125, 0.01563, and 0.007813 microg/mL and assay samples prepared by diluting mouse plasma samples 100-fold or more were aliquoted into the Anti-Human IgG-immobilized plates, and then the plates were incubated at 25 degrees C. for one hour. Next, Goat Anti-Human IgG (gamma-chain specific) Biotin (BIOT) Conjugate (Southern Biotechnology Associates Inc.) was aliquoted into each well of the plates, and then the plates were incubated at 25 degrees C. for one hour. Then, Streptavidin-PolyHRP80 (Stereospecific Detection Technologies) was added to each well of the plates, after which the plates were incubated at 25 degrees C. for one hour. The chromogenic reaction using TMB One Component HRP Microwell Substrate (BioFX Laboratories) as a substrate was terminated with 1N sulfuric acid (Showa Chemical), and then the reaction mixture in each well was measured using a microplate reader to measure the absorbance at 450 nm. The anti-hIgA antibody concentration in mouse plasma was calculated from the absorbance of the standard curve using analysis software SOFTmax PRO (Molecular Devices). The time course of plasma antibody concentrations of GA2-F1331, and GA2-F760 in human FcRn transgenic mice, which were determined by the method described above, is shown in
10-3. Determination of hIgA Concentration in Plasma by ELISA
hIgA concentrations in mouse plasma were measured by ELISA. First, Anti-Human IgA-immobilized plates were prepared by aliquoting Goat anti-Human IgA Antibody (BETHYL) into each well of Nunc-Immuno Plate, MaxiSorp (Nalge nunc International) and allowing the plates to stand at 4 degrees C. overnight. hIgA standard curve samples were prepared as standard solutions at plasma concentrations of 0.4, 0.2, 0.1, 0.05, 0.025, 0.0125, and 0.00625 microg/mL and assay samples were prepared by diluting mouse plasma samples 100-fold or more. Each sample (100 microL) was mixed with 200 microL of 500 ng/mL hsIL-6R at room temperature for one hour, and then it was aliquoted at 100 microL/well into the Anti-Human IgA-immobilized plates. The resulting plates were allowed to stand at room temperature for one hour. Next, after adding Biotinylated Anti-human IL-6R Antibody (R&D) into each well of the plates, the plates were incubated at room temperature for one hour. Then, after aliquoting Streptavidin-PolyHRP80 (Stereospecific Detection Technologies) into each well of the plates, the plates were incubated at room temperature for one hour. The chromogenic reaction using as a substrate TMB One Component HRP Microwell Substrate (BioFX Laboratories) was terminated with 1N sulfuric acid (Showa Chemical), and then the reaction mixture in each well was measured using a microplate reader to measure the absorbance at 450 nm. The concentration in mouse plasma was calculated from the absorbance of the standard curve using analysis software SOFTmax PRO (Molecular Devices). The time course of plasma hIgA concentrations in human FcRn transgenic mice after intravenous administration, as determined by the method described above, is shown in
The result showed that the elimination of hIgA was markedly accelerated when hIgA was administered in combination with GA2-F1331, an antibody that exhibits strong human FcRn binding, as compared to when hIgA was administered in combination with GA2-F760, which has very weak affinity to human FcRn.
To prepare pH-dependent anti-human IgE antibodies, human IgE (heavy chain SEQ ID NO: 18; light chain SEQ ID NO: 19) (the variable region is derived from an anti-human glypican3 antibody) as an antigen was expressed using FreeStyle293 (Life Technologies). Human IgE was prepared by purifying the expressed human IgE using a conventional chromatographic method known to those skilled in the art.
An antibody that binds to human IgE in a pH-dependent manner was selected from a number of obtained antibodies. The selected anti-human IgE antibody was expressed using human IgG1 heavy chain constant region and human light chain constant region, and then purified. The produced antibody was named clone 278 (heavy chain SEQ ID NO: 20; light chain SEQ ID NO: 21).
11-2. Assessment of Anti-Human IgE Antibodies for their Binding Activity and pH-Dependent Binding Activity
Antibodies capable of dissociating from antigens within the endosome can be created not only by designing them so as to bind to antigens in a pH-dependent manner, but also by designing them so as to bind to antigens in a Ca-dependent manner. Thus, clone 278 and the control Xolair (omalizumab; Novartis) whose IgE-binding activity does not depend on pH/Ca were assessed for their pH dependency and pH/Ca dependency of the human IgE (hIgE)-binding activity.
More specifically, the hIgE-binding activities (dissociation constant KD (M)) of clone 278 and Xolair were assessed using Biacore T200 (GE Healthcare). Running buffers used in the assay were:
1.2 mmol/l CaCl2/0.05% tween20, 20 mmol/l ACES, 150 mmol/l NaCl, pH 7.4;
1.2 mmol/l CaCl2/0.05% tween20, 20 mmol/l ACES, 150 mmol/l NaCl, pH 5.8; and
3 micromol/l CaCl2/0.05% tween20, 20 mmol/l ACES, 150 mmol/l NaCl, pH 5.8.
A chemically-synthetized peptide having a human glypican 3 protein-derived sequence (SEQ ID NO: 22) whose C-terminal Lys is biotinylated (hereinafter abbreviated as “biotinylated GPC3 peptide”) was added in an appropriate amount and immobilized onto Sensor chip SA (GE Healthcare) based on the affinity between biotin and streptavidin. Human IgE was immobilized onto the chip by injecting it at an appropriate concentration so as to be trapped by the biotinylated GPC3 peptide. As an analyte, clone 278 was injected at an appropriate concentration and allowed to interact with the human IgE on the sensor chip. Then, 10 mmol/L glycine-HCl (pH 1.5) was injected to regenerate the sensor chip. The interaction was always measured at 37 degrees C. The measurement result was analyzed by curve fitting using Biacore T200 Evaluation Software (GE Healthcare) to calculate the association rate constant ka (1/Ms) and dissociation rate constant kd (1/s). The dissociation constant KD (M) was calculated from the above-described constants. Furthermore, the KD ratios in each antibody under the conditions of [pH 5.8, 1.2 mM Ca] to [pH 7.4, 1.2 mM Ca] were calculated to assess the pH-dependent binding, while the KD ratios in each antibody under the conditions of [pH 5.8, 3 microM Ca] to [pH 7.4, 1.2 mM Ca] were calculated to assess the pH/Ca-dependent binding. The result is shown in Table 30.
Next, to evaluate the effect of FcRn binding on antigen (human IgE) elimination from plasma, 278-F760 (heavy chain SEQ ID NO: 23; light chain SEQ ID NO: 21) was constructed to eliminate binding to FcgammaR. Furthermore 278-F1331 (heavy chain SEQ ID NO: 24; light chain SEQ ID NO: 21) was constructed by introducing amino acid substitution G236R, M252Y, S254T, T256E, N434Y, Y436V, Q438R and S440E into 278-F760, which binds to FcRn stronger than 278-F760 at pH 7.4. The modified antibodies were expressed by the method described above using animal expression plasmids inserted with DNA sequences encoding 278-F1331 (heavy chain SEQ ID NO: 24; light chain SEQ ID NO: 21) and 278-F760 (heavy chain SEQ ID NO: 23; light chain SEQ ID NO: 21) by a method known to those skilled in the art. The antibody concentrations were determined after purification.
13-1. Preparation of Human IgE (hIgE(Asp6)) for In Vivo Assessment
hIgE(Asp6) (the variable region is derived from an anti-human glypican3 antibody), which is a human IgE for in vivo assessment consisting of a heavy chain (SEQ ID NO: 25) and a light chain (SEQ ID NO: 19), was produced by the same method as described in Example 11. hIgE(Asp6) is a modified molecule resulting from asparagine-to-aspartic acid alteration at the six N-linked glycosylation sites in human IgE so that the heterogeneity in the N-linked sugar chain of human IgE is not affected by time-dependent changes in the plasma concentration of human IgE as an antigen.
Pharmacokinetics of hIgE(Asp6) and anti-human IgE antibody was assessed after administration of hIgE(Asp6) in combination with an anti-hIgE antibody (278-F760 and 278-F1331) and Sanglopor (Human normal Immunoglobulin, CSL Behring) to human FcRn transgenic mice (B6.mFcRn−/−.hFcRn Tg line 32+/+ mouse, Jackson Laboratories; Methods Mol Biol. (2010) 602: 93-104). A mixture of hIgE(Asp6), anti-human IgE antibody and Sanglopor (the concentrations are shown in Table 31) was administered once at a dose of 10 mL/kg via the caudal vein. Under the conditions described above, hIgE(Asp6) is predicted to bind almost completely to the antibody since each antibody is present sufficiently in excess over hIgE(Asp6). Blood was collected from the mice five minutes, two hours, seven hours, one day, two days, four or five days, seven days, fourteen days, twenty-one days, and twenty-eight days after administration. The collected blood was immediately centrifuged at 15,000 rpm and 4 degrees C. for 5 minutes to obtain plasma. The separated plasma was stored in a freezer at −20 degrees C. or below until measurement.
Anti-hIgE antibody concentrations in mouse plasma were determined by electrochemiluminescence (ECL) assay. Standard curve samples were prepared at plasma concentrations of 32, 16, 8, 4, 2, 1, 0.5, and 0.25 microgram/mL. The standard curve samples and mouse plasma assay samples were aliquoted into ECL plates immobilized with hIgE(Asp6). The plates were allowed to stand at 4 degrees C. overnight. Then, Anti Rabbit Antibody (Goat), SULFO-TAG Labeled (Meso Scale Discovery) was reacted at room temperature for one hour. Immediately after Read Buffer T (×4) (Meso Scale Discovery) was dispensed, the measurement was performed by the Sector Imager 2400 Reader (Meso Scale Discovery). The concentration in mouse plasma was calculated from the response of the standard curve using analysis software SOFTmax PRO (Molecular Devices). A time course of the plasma antibody concentration after intravenous administration, which was determined by the method described above, is shown in
13-4. Determination of Plasma hIgE(Asp6) Concentration in Human FcRn Transgenic Mice
hIgE(Asp6) concentrations in mouse plasma were determined by ELISA. Standard curve samples were prepared at plasma concentrations of 192, 96, 48, 24, 12, 6, and 3 ng/mL. Xolair (Novartis) was added at 10 microgram/mL to the standard curve samples and mouse plasma assay samples to equalize the immune complex of hIgE(Asp6) and anti-hIgE antibody. After 30 minutes of incubation at room temperature, the standard curve samples and mouse plasma assay samples were aliquoted into immunoplates (MABTECH) immobilized with anti-human IgE antibody or immunoplates (Nunc F96 MicroWell Plate (Nalge nunc International)) immobilized with anti-human IgE antibody (clone 107; MABTECH). The plates were allowed to stand at room temperature for two hours or at 4 degrees C. overnight. Then, human GPC3 core protein (SEQ ID NO: 26), anti-GPC3 antibody biotinylated with NHS-PEG4-Biotin (Thermo Fisher Scientific) (prepared in Chugai pharmaceutical Co., Ltd.), and Sterptavidin-PolyHRP80 (Stereospecific Detection Technologies) were reacted sequentially for one hour each. The chromogenic reaction using as a substrate TMB One Component HRP Microwell Substrate (BioFX Laboratories) was terminated with 1N sulfuric acid (Showa Chemical), and then the concentration in mouse plasma was determined by a method in which the color development is assessed by measuring the absorbance at 450 nm using a microplate reader or a method in which a luminescent reaction is carried out using SuperSignal(r) ELISA Pico Chemiluminescent Substrate (Thermo Fisher Scientific) as a substrate and the luminescence intensity is measured with a microplate reader. The concentration in mouse plasma was calculated from the absorbance or luminescence intensity of the standard curve using analysis software SOFTmax PRO (Molecular Devices). The time course of plasma hIgE(Asp6) concentration after intravenous administration, which was determined by the method described above, is shown in
The result showed that the elimination of human IgE was significantly accelerated when human IgE was administered in combination with 278-F1331, which binds to human FcRn much stronger than 278-F760. Specifically, it was demonstrated that not only in the case of IL6R and IgA, but also in the case of IgE, a pH-dependent antigen binding antibody having increased binding activity to FcRn can accelerate antigen clearance from plasma and decrease concentration of antigen in plasma.
Recombinant human IL-6 receptor as an antigen was prepared as follows. A cell line constitutively expressing soluble human IL-6 receptor (hereinafter referred to as hsIL-6R) having the amino acid sequence of positions 1 to 357 from the N terminus as reported in J. Immunol. 152: 4958-4968 (1994) was established by a method known to those skilled in the art. The cells were cultured to express hsIL-6R. The hsIL-6R was purified from the culture supernatant by two steps: Blue Sepharose 6 FF column chromatography and gel filtration chromatography. A fraction eluted as the main peak in the final stage was used as the final purification product.
FcRn is a heterodimer of FcRn alpha chain and beta2-microglobulin. Oligo-DNA primers were prepared based on the published human FcRn gene sequence (J Exp Med. 1994 Dec. 1; 180(6): 2377-81). A DNA fragment encoding the whole gene was prepared by PCR using human cDNA (Human Placenta Marathon-Ready cDNA, Clontech) as a template and the prepared primers. Using the obtained DNA fragment as a template, a DNA fragment encoding the extracellular domain containing the signal region (Met1-Leu290) was amplified by PCR, and inserted into a mammalian cell expression vector. Likewise, oligo-DNA primers were prepared based on the published human beta2-microglobulin gene sequence (Proc. Natl. Acad. Sci. U.S.A. 99 (26): 16899-16903 (2002)). A DNA fragment encoding the whole gene was prepared by PCR using human cDNA (Human Placenta Marathon-Ready cDNA, Clontech) as a template and the prepared primers. Using the obtained DNA fragment as a template, a DNA fragment encoding the whole protein containing a signal region (Met1-Met119) was amplified by PCR and inserted into a mammalian cell expression vector.
Soluble human FcRn was expressed by the following procedure. The plasmids constructed for expressing human FcRn alpha chain (SEQ ID NO: 27) and beta2-microglobulin (SEQ ID NO: 28) were introduced into cells of the human embryonic kidney cancer-derived cell line HEK293H (Invitrogen) by the lipofection method using PEI (Polyscience). The resulting culture supernatant was collected, and FcRn was purified using IgG Sepharose 6 Fast Flow (Amersham Biosciences), followed by further purification using HiTrap Q HP (GE Healthcare) (J Immunol. 2002 Nov. 1; 169(9): 5171-80).
hIgA comprising H (WT)-IgA1 (SEQ ID NO: 12) and L (WT) (SEQ ID NO: 13) was expressed and purified by the method known to those skilled in the art using rProtein L-agarose (ACTIgen) followed by gel filtration chromatography.
Recombinant soluble human plexin A1 as an antigen (hereinafter referred to as hsPlexin A1) was prepared as follows. hsPlexin A1 was constructed by reference to NCBI Reference Sequence (NP—115618). Specially, hsPlexin A1 was comprised of the amino acid sequence of positions 27-1243 from the above-mentioned NCBI Reference FLAG-tag (DYKDDDDK, SEQ ID NO: 29) was connected to its C terminus. hsPlexin A1 was transiently expressed using FreeStyle293 (Invitrogen) and purified from the culture supernatant by two steps: anti-FLAG column chromatography and gel filtration chromatography. A fraction eluted as the main peak in the final stage was used as the final purification product.
When a conventional antibody targeting soluble antigen is administered to a subject, the antigen binds to the antibody and persists stably in plasma. Since an antigen bound to an antibody has a significantly longer half-life than an antigen alone, the antigen concentration increases after the injection of a conventional antibody to approximately 10 to 1000-folds of total plasma antigen concentration from the baseline. Such an increase of the total plasma antigen concentration is not preferable for a therapeutic antibody, because the antibody concentration (dosage) has to be 10 to 1000-fold higher than necessary compared to when no substantial increase in total plasma antigen concentration occurs. Therefore, an antibody which eliminates the antigen from plasma and also reduces the total plasma antigen concentration compared to a conventional antibody is extremely valuable since the required dosage would be 10 to 1000-fold lower than that required for a conventional antibody.
The present inventors conducted dedicated studies on modified FcRn-binding domains which have an enhanced affinity for FcRn at neutral pH and antigen-binding molecules comprising said FcRn-binding domain which have low immunogenicity, high stability and form only a few aggregates. As a result, it was discovered that substitutions at specific positions of the FcRn-binding domain increases the affinity for the FcRn at neutral pH without substantially increasing the immunogenicity and the ratio of high molecular weight species, and without substantially decreasing stability of antigen-binding molecules comprising the FcRn-binding domain. The antigen-binding molecules comprising the FcRn-binding domain of the present invention are superior in pharmacokinetics in facilitating the reduction of the plasma antigen concentration and meet the developability criteria of low immunogenicity, high stability and very few aggregates.
Furthermore, Fc-engineering to increase the binding affinity to FcRn at neutral or acidic pH can improve the endosomal recycling efficiency and the pharmacokinetics of the antibody. However, modifications of the amino acid sequence of an antibody (e.g. amino acid substitutions and insertions) can also increase the immunogenicity of the therapeutic antibody which, in turn, can result in a cytokine storm and/or production of anti-drug antibodies (ADA).
The present inventors conducted dedicated studies on antigen-binding molecules comprising a modified FcRn-binding domain whose binding activity for a pre-existing anti-drug antibody (ADA) was increased at neutral pH due to substitutions in the FcRn-binding domain that increased the affinity for FcRn at neutral pH or acidic pH. As a result, it was discovered that other substitutions at specific positions of the FcRn-binding domain decrease the binding activity for a pre-existing anti-drug antibody (ADA) at neutral pH while maintaining to a high extent the increased FcRn-binding activity in the respective pH ranges. The antigen-binding molecules of the present invention are superior in pharmacokinetics in facilitating the reduction of the plasma antigen concentration without increasing the antibody clearance.
[Sequence Listing]
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-218736 | Sep 2011 | JP | national |
| PCT/JP2012/058603 | Mar 2012 | JP | national |
| 2012-123773 | May 2012 | JP | national |
| 2012-123781 | May 2012 | JP | national |
| 2012-123782 | May 2012 | JP | national |
| 2012-139211 | Jun 2012 | JP | national |
| 2012-177311 | Aug 2012 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2012/006218 | 9/28/2012 | WO | 00 | 7/25/2014 |
