Patent Application
20250152760
In accordance with 37 CFR § 1.831-1835 and 37 CFR § 1.77 (b) (5), the specification makes reference to a Sequence Listing submitted electronically as a .xml file named “554486US_012925_ST26.xml”. The .xml file was generated on Jan. 29, 2025 and is 32,047 bytes in size. The entire contents of the Sequence Listing are hereby incorporated by reference.
The present invention relates to a radioactive conjugate of an anti-VEGF antibody, and a radiopharmaceutical.
Vascular endothelial growth factor (VEGF) is a group of glycoproteins involved in vasculogenesis and angiogenesis. It binds as a ligand to the vascular endothelial growth factor receptor (VEGFR) on the surface of vascular endothelial cells, and has the functions of stimulating cell division, migration, and differentiation, and promoting vascular permeability of microvessels. In addition, it is known to be involved in the activation of monocytes and macrophages. There are seven growth factors of VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, PlGF (placental growth factor)-1, and PlGF-2, that are involved in vasculogenesis, angiogenesis, and lymphangiogenesis. These are collectively referred to as the “VEGF family”. Furthermore, some VEGF family members have several subtypes due to alternative splicing. For example, in human, VEGF-A generally exist in four types, with 121 amino acids (VEGF-A121), 165 amino acids (VEGF-A165), 189 amino acids (VEGE-A189), and 206 amino acids (VEGE-A206), and rare subtypes such as VEGE-A145 and VEGF-A183 have also been reported. VEGF-B167 and VEGF-B186 are known for VEGF-B.
Anti-VEGF antibodies act, for example, by preventing VEGF from binding to cell receptors, by preventing activation of vascular endothelial cells after the binding of VEGE to cell receptors, or by killing cells activated by VEGF, Examples of the anti-VEGF antibody include bevacizumab (trade name: avastin), aflibercept beta (trade name: ZALTRAP), aflibercept (trade name: Eylea), and brolucizumab (trade name: Beovu).
Antibody drugs have high target selectivity and relatively few side effects; on the contrary, the efficacy thereof is insufficient in some cases. In contrast, chemotherapeutic agents have strong efficacy, but low target selectivity. Accordingly, the minimum effective dose required to kill cancer cells is high, whereas the maximum tolerated dose is low because the dose cannot be increased much in view of toxicity, and the therapeutic dose range is problematically narrow.
One technology that compensates for these shortcomings is antibody-drug conjugate (ADC). ADC uses antibodies to narrow down target cells (e.g. cancer cells) and delivers a drug (payload) attached to the antibody directly into the target cells. As a result, the biological activity of the drug is exerted target cell-specifically while avoiding an influence on normal cells.
Using ADC, it is possible to selectively deliver large amounts of chemotherapeutic agents to the target cells, and as a result, smaller doses show effects, the amount of chemotherapeutic agent that reaches normal cells decreases, the maximum tolerated dose increases, and the therapeutic dose range is expected to become wide.
One approach to ADC is a radioimmunoconjugate. In the radioimmunoconjugate, a radionuclide is used instead of payload.
As a site-specific chemical modification to add a function without affecting the specificity of antibody to a target molecule, a technique has been reported in which an amino acid capable of binding to a crosslinking agent is introduced into a peptide that specifically or selectively binds to an antibody (hereinafter also referred to as an antibody-modification peptide), and the amino acid is modified with a crosslinking agent to prepare an antibody-modification peptide that is site-specifically modified with a crosslinking agent, and then the antibody-modification peptide is used to site-specifically modify the antibody (Patent Literatures 1, 2).
In addition, Patent Literatures 3, 4 disclose techniques relating to some methods for labeling an antibody with a radionuclide.
In addition, Non Patent Literature 1 has reported the results of labeling an anti-VEGE antibody bevacizumab with zirconium-89, administering same to humans, and taking images by positron emission tomography (PET) method. In this example, a method is disclosed in which Fe—N-suc-Df-TEP is randomly bound to the amino groups of bevacizumab, and zirconium-89 is chelated to deferoxamine (DE).
Bevacizumab specifically binds to human VEGF, thereby inhibiting the binding of VEGE to VEGF receptor expressed on vascular endothelial cells, and inhibits the biological activity of VEGE, thereby suppressing angiogenesis in tumor tissues and inhibiting tumor growth. However, sufficient effects cannot be obtained when used alone, and combined use with other drugs (anticancer agents) has been essential in clinical practice.
The effect of radiotherapy using bevacizumab is not yet known.
Moreover, site-specifically radionuclide-modified bevacizumab is not yet known.
Therefore, the present invention aims to provide a novel radiolabeled anti-VEGF antibody applicable to nuclear medicine diagnosis or radiotherapy.
One embodiment of the present invention is a conjugate of an antibody site-specifically modified with an antibody-modification peptide and a chelating agent, wherein the antibody is an anti-VEGF antibody and a metal radionuclide is chelated to the chelating agent.
Another embodiment of the present invention is a radiopharmaceutical containing the above-mentioned conjugate as an active ingredient.
The “linking” in the present invention means both direct connection and indirect connection, unless otherwise specified.
According to the present invention, a novel radiolabeled anti-VEGF antibody applicable to nuclear medicine diagnosis or radiotherapy is provided.
The present invention is a conjugate of an antibody site-specifically modified with an antibody-modification peptide and a chelating agent, wherein the antibody is an anti-VEGE antibody and a metal radionuclide is chelated to the chelating agent (hereinafter also to be referred to as the radioactive conjugate of the present invention).
The metal radionuclide contained in the radioactive conjugate of the present invention is a radionuclide that emits α-ray, a radionuclide that emits β-ray, a radionuclide that emits positron, or a radionuclide that emits γ-ray. When the radioactive conjugate of the present invention is used for cancer therapy, it is preferable to use a radionuclide that emits α-ray or a radionuclide that emits β-ray. When the radioactive conjugate of the present invention is used for cancer diagnosis or detection, it is preferable to use a radionuclide that emits positron, or a radionuclide that emits γ-ray. Examples of the radionuclide that emits α-ray include Bi-212, Bi-213, Ac-225, and Th-227. Examples of the radionuclide that emits β-ray include Cu-64, Y-90, and Lu-177. Examples of the radionuclide that emits positron include Cu-64, Ga-68, Y-86, and Zr-89. Examples of the radionuclide that emits γ-ray include Tc-99m and In-111. The metal radionuclide to be contained in the radioactive conjugate of the present invention is more preferably Ga-68, Zr-89, Y-90, In-111, Lu-177, or Ac-225.
The antibody contained in the radioactive conjugate of the present invention is an immunoglobulin that specifically binds to the vascular endothelial cell growth factor (VEGF) (hereinafter also to be referred to as the antibody to be used in the present invention). The antibody to be used in the present invention may be a polyclonal antibody or a monoclonal antibody, preferably a monoclonal antibody. The origin of the antibody is not particularly limited, and examples include antibodies of non-human animals, non-human mammals, and humans, preferably antibodies of human, rat, mouse, and rabbit. When the antibody is derived from species other than human, it is preferably chimerized or humanized using well-known techniques. The antibody to be used in the present invention may be a chimera antibody, a humanized antibody, or a human antibody. The antibody to be used in the present invention may be a bispecific antibody. The antibody may be an isolated antibody or a purified antibody. The antibody may be, for example, IgG. The antibody may be, for example, IgG1, IgG2 (e.g., IgG2a and IgG2b), IgG3, or IgG4.
The antibody used in the radioactive conjugate of the present invention is not limited as long as it is an anti-VEGF antibody. For example, bevacizumab, aflibercept beta, aflibercept, and brolucizumab can be mentioned, and bevacizumab is more preferred.
Bevacizumab is a monoclonal antibody against VEGF. It has the actions of suppressing angiogenesis and suppressing the growth and metastasis of tumors by inhibiting the function of VEGF. It is one of the molecular targeted drugs, is used as an anticancer agent, and is expected to be a therapeutic drug for age-related macular degeneration and diabetic retinopathy. Bevacizumab is a glycoprotein consisting of two light chain molecules of 214 amino acid residues (C1034H1591N273O358S6; molecular weight: 23446.71) and two heavy chain molecules of 453 amino acid residues (C2235H3413N585O678S16; molecular weight:about 49838.57: including one lacking one lysine residue at the C-terminus) produced in Chinese hamster ovary cells by expression of cDNA encoding a humanized monoclonal antibody consisting of the complementarity determining region of a mouse anti-VEGF monoclonal antibody and the framework region and constant region derived from human IgG1.
Bevacizumab is also known as AVASTIN (registered trademark) and various biosimilar products (bevacizumab BS), and can be produced, for example, according to a previous report (Presta et al., Cancer Res. (1997) 57:4593-4599). Specifically, it has the following structure.
Here, intramolecular disulfide bonds are shown with solid line.
H chain E1: partial pyroglutamic acid; H chain N303: sugar chain bond; H chain K453: partial processing L chain C214-H chain C226, H chain C232-H chain C232, H chain C235-H chain C235: disulfide bonds
The sugar chain structure is shown below.
wherein Fuc is L-fucose, (Gal)0-2 is D-galactose with 0, 1, or 2 molecules, GlcNac is D-N-acetylglucosamine, and Man is D-mannose.
Aflibercept beta is a recombinant fusion glycoprotein, consisting of the second immunoglobulin (Ig)-like C2 domain of human vascular endothelial growth factor receptor (VEGFR) 1. (from the 1st to 104th), the third Ig-like C2 domain of human VEGFR2 (from the 105th to 205th), and the Fc domain of human IgG1 (from the 206th to 432nd). Aflibercept beta is produced in Chinese hamster ovary cells. Aflibercept beta is a glycoprotein (molecular weight: about 115,000) consisting of two subunits of 432 amino acid residues, and is commercially available under the trade name ZALTRAP (registered trademark).
Aflibercept is also available as Eylea (registered trade mark) and brolucizumab is available as Beovu (registered trade mark).
In the present invention, the chelating agent is not particularly limited as long as it has a site in the structure thereof where metal radionuclide is coordinated. Examples of the chelating agent include CB-TE2A (1,4,8,11-tetraazabicyclo[6.6.2]hexadecane-4,11-diacetic acid), CDTA (cyclohexane-trans-1,2-diamine tetra-acetic acid), CDTPA (4-cyano-4-[[(dodecylthio)thioxomethyl]thio]pentanoic acid), DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), DOTMA ((1R,4R,7R,10R)-α,α′,α″,α″″-tetramethyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), DOTAM (1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane), DOTA-GA (α-(2-carboxyethyl)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), DOTP (((1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetrakis(methylene))tetraphosphonic acid), DOTMP (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylenephosphonic acid)), DOTA-4AMP (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(acetamidomethylenephosphonic acid), D02P (tetraazacyclododecane dimethanephosphonic acid), Deferoxamine (DFO), DTPA (Glycine, N,N-bis[2-[bis(carboxymethyl)amino]ethyl]-), DTPA-BMA (5,8-bis(carboxymethyl)-11-[2-(methylamino)-2-oxoethyl]-3-oxo-2,5,8,11-tetraazatridecan-13-oic acid), EDTA (2,2′,2″,2′″-(ethane-1,2-diylbis(azanetriyl))tetraacetic acid), NOTA (1,4,7-triazacyclononane-1,4,7-triacetic acid), NOTP (1,4,7-triazacyclononane-1,4,7-triyltris(methylenephosphonic acid)), TETPA (1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetrapropionic acid), TETA (1,4,8,11-tetraazacyclotetradecane-N,N′,N″,N′″-tetraacetic acid), TTHA (3,6,9,12-tetrakis(carboxymethyl)-3,6,9,12-tetraazatetradecanedioic acid) HEHA (1,2,7,10,13-hexaazacyclooctadecane-1,4,7,10,13,16-hexaacetic acid), 1,2-HOPO (N,N′,N″,N′″-tetra(1,2-dihydro-1-hydroxy-2-oxopyridine-6-carbonyl)-1,5,10,14-tetraazatetradecane), PEPA (1,4,7,10,13-pentaazacyclopentadecane-N,N′,N″,N′″,N″″-pentaacetic acid), H4octapa (N,N′-bis(6-carboxy-2-pyridylmethyl)-ethylenediamine-N,N′-diacetic acid), H2bispa2 (6,6′-({9-hydroxy-1,5-bis(methoxycarbonyl)-2,4-di(pyridin-2-yl)-3,7-diazabicyclo[3.3.1]nonane-3,7-diyl}bis(-methylene))dipicolinic acid), H2dedpa (1,2-[{6-(carboxy)-pyridin-2-yl}-methylamino]ethane), H2macropa (6-(1,4,10,13-tetraoxa-7,16-diazacyclooctadecan-N,N′-methyl) picolinic acid), H5decapa (N,N″-bis(6-carboxy-2-pyridylmethyl)-diethylenetriamine-N,N′,N″-triacetic acid), H6phospa (N,N′-(methylenephosphonate)-N,N′-[6-(methoxycarbonyl)pyridin-2-yl]-methyl-1,2-diaminoethane), HP-D03A. (hydroxypropyltetraazacyclododecanetriacetic acid), and porphyrin. A compound represented by the following formula (A) is preferred.
In the formula (A), R11, R12, R13 and R14 are each independently a group consisting of —(CH2)pCOOH, —(CH2)pC5H4N, —(CH2)pPO3H2, —(CH2)pCONH2, or —(CHCOOH)(CH2)pCOOH, R15 is a hydrogen atom, and p is an integer of not less than 0 and not more than 3.
The compound represented by the formula (A) is preferably a compound containing a structure derived from 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), or derivative thereof. Specifically, the compound can contain, in its structure, a structure derived from one chelating agent selected from DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), DOTMA ((1R,4R,7R,10R)-α,α″,α′″-tetramethyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), DOTAM (1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane), DOTPA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrapropionic acid), LPY (1,4,7,10-tetrakis(pyridin-2-ylmethyl)-1,4,7,10-tetraazacyclododecane), DOTA-GA (α-(2-carboxyethyl)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), DOTP (((1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetrakis(methylene))tetraphosphonic acid), DOTMP (1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetrakis(methylenephosphonic acid)), DOTA-4AMP (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(acetamidomethylenephosphonic acid), and D02P (tetraazacyclododecane dimethanephosphonic acid). More preferably, compounds represented by the following formulas (A-1) to (A-6) can be mentioned. The chelating agent to be used in the radioactive conjugate of the present invention is further preferably DOTA-GA (compound represented by the formula (A-6)). When the chelating agent used is DOTA-GA, the aforementioned chelating agent may be a stereoisomer (S-form, R-form) or a racemate, and in the racemate, the S-form and R-form stereoisomers may be mixed at any ratio.
The chelating agent used in the present invention is preferably linked to the peptide via a linker (L). Specifically, in the radioactive conjugate of the present invention, the chelating agent and the linker (L) are preferably connected by a covalent bond. Therefore, in the radioactive conjugate of the present invention, some groups in the compound of the aforementioned chelating agent may be substituted by groups that form covalent bonds with the linker (L). For example, when the chelating agent used in the present invention is a compound represented by the formula (A), R12 or R15 may be substituted by a group that forms a covalent bond with the linker (L). Preferably, when R12 is substituted by a group that forms a covalent bond with the linker (L), R15 is a hydrogen atom, when R12 is a group consisting of —(CH)pCOOH, —(CH2)pC5H4N, —(CH2)pPO3H2, —(CH2)pCONH2, or —(CHCOOH)(CH2)pCOOH, R15 is substituted by a group that forms a covalent bond with the linker (L).
The covalent bond between the chelating agent and the linker (L) preferably does not include a thiourea bond. In this case, a complex with improved stability can be provided without impairing the medicinal effect. Examples of the covalent bond between the chelating agent and the linker (L) include a carbon-carbon bond, an amide bond, an ether bond, and an ester bond.
The connection between the chelating agent and the linker (L) can be formed, for example, by the reaction of an N-hydroxysuccinimide ester (NHS) group of the following formula (A-7) or (A-8), or a 2,6-dioxotetrahydro-2H-pyranyl group of the following formula (A-9), with the primary amine of linker (L).
The antibody-modification peptide used in the present invention is not particularly limited as long as it site-specifically modifies an antibody, preferably site-specifically modifies the Fc region, more preferably site-specifically modifies the lysine residue in the Fc region of an antibody. The activity of the antibody itself (antigen recognition action, neutralizing action, complement activating action and/or opsonin action) can be maintained thereby.
The antibody-modification peptide used in the present invention may be a linear peptide or a cyclic peptide, and a cyclic peptide is preferred. More preferably, it contains peptide consisting of not less than 13 and not more than 17 amino acid residues represented by the following formula (i) and is modified with a crosslinking agent. In the explanation of formula (i), the left side of the paper surface of the amino acid sequence indicates the N-terminal side, and the right side of the paper surface of the amino acid sequence indicates the C-terminal side.
(Xa)-Xaa1-(Xb)-Xaa2-(Xc)-Xaa3-(Xd) (i)
In the formula (i), Xa, Xb, Xc and Xd are each continuous x in the number of a, continuous X in the number of b, continuous X in the number of c, and continuous X in the number of, respectively,
Examples of the amino acid residue that may be contained in X in the above-mentioned formula (i) include those derived from amino acids such as glycine, alanine, phenylalanine, proline, asparagine, aspartic acid, glutamic acid, arginine, histidine, serine, threonine, tyrosine, methionine and the like, and X may be an amino acid residue consisting of the same type of amino acid, or different types of amino acids.
In the formula (i), a, b, c and d are not particularly limited as long as they are numbers within the aforementioned range. From the aspect of the stability of binding between the peptide and anti-VEGF antibody, a+b+c+d≤14 is to be satisfied, and a is preferably an integer of not less than 1 and not more than 3, bis preferably an integer of not less than 1 and not more than 3, c is preferably an integer of not less than 3 and not more than 5, and d is preferably an integer of not less than 1 and not more than 3.
At least one of Xaa1 and Xaa3 is an amino acid residue derived from an amino acid having a thiol group in the side chain, and the amino acid may be the same or different. Examples of the amino acid having a thiol group in the side chain include cysteine and homocysteine. Such amino acid residues are preferably bonded by a disulfide bond, or a sulfide group is preferably bonded thereto via a structure shown by the following formula (4). In the formula (4), the broken line indicates the binding part with the sulfide group.
Instead of the aforementioned combination of Xaa1 and Xaa3, one of Xaa1 and Xaa3 may be an amino acid residue derived from an amino acid having a thiol group in the side chain, and the other may be an amino acid residue derived from an amino acid having a haloacetyl group in the side chain. These are bonded via a thioether bond. The terminal of the haloacetyl group is substituted with a halogen such as iodine or the like, and the halogen is eliminated by a reaction with the thiol group in the other side chain, whereby a thioether bond is formed.
Specific examples of the amino acid sequence of the antibody-modification peptide represented by the formula (i) include the peptides described in WO 2016/186206, WO 2017/217347 and WO 2018/230257, and these can also be used.
Preferably, the antibody-modification peptide used in the present invention has an amino acid sequence consisting of 13 to 17 amino acid residues represented by the following formula (i)′:
(X1-3)—C—(Xaa3′)-(Xaa4′)—H—(Xaa1′)-G-(Xaa1′)-L-V-W—C—(X1-3) (i)′
In the formula (i)′, each X is independently any amino acid residue other than cysteine,
In the above-mentioned formula (i)′, the notation X1-3 at the N-terminus or C-terminus means that 1 to 3 consecutive amino acid residues X, which are independently any amino acid residue other than cysteine (C or Cys), are present, the amino acid residues that constitute the same may be the same or different residues, and preferably all three are not the same residue.
Among these, the amino acid sequence of the antibody-modification peptide preferably has any one of the following sequences (1) to (14), more preferably the following sequence (1), (2), (13) or (14). In the following amino acid sequences (1) to (14), (Xaa) is a lysine residue, a cysteine residue, an aspartic acid residue, a glutamic acid residue, a 2-aminosuberic acid, or a diaminopropionic acid, preferably a lysine residue, and is preferably modified with a crosslinking agent, and (Xaa1) and (Xaa3) are each a homocysteine residue. In the following amino acid sequences (1) to (14), the amino acids other than (Xaa1), (Xaa2) and (Xaa3) are indicated by one-letter abbreviations.
The peptides represented by the above-mentioned formula (i) or (i)′ or the peptides having sequences (1) to (14) preferably have a linker (L) introduced at the N-terminus, and the C-terminus is amidated. Furthermore, Xaa2 (or a portion corresponding to Xaa2) of these peptides is modified with a crosslinking agent, whereby the peptides are covalently bound to the Fc region of an anti-VEGF antibody via the crosslinking agent.
The crosslinking agent can be appropriately selected by those of ordinary skill in the art, and can be a compound having at least two sites bindable to desired amino acid (e.g., lysine, cysteine, aspartic acid, glutamic acid, 2-aminosuberic acid, diaminopropionic acid, arginine, etc.). Examples thereof include, but are not limited to, a crosslinking agent preferably containing two or more succinimidyl groups such as DSG (disuccinimidyl glutarate), DSS (disuccinimidyl suberate), and the like, a crosslinking agent preferably containing two or more imide acid moieties such as DMA (dimethyl adipimidate·2HCl, dimethyl adipimidate dihydrochloride), DMP (dimethyl pimelimidate·2HCl, dimethyl pimelimidate dihydrochloride), DMS (dimethyl suberimidate·2HCl, dimethyl suberimidate dihydrochloride), and the like, and a crosslinking agent having an SS bond such as DTBP (dimethyl 3,3′-dithiobispropionimidate·2HCl, dimethyl 3,3′-dithiobispropionimidate dihydrochloride), and DSP (dithiobis(succinimidyl propionate)), and SBAP (succinimidyl 3-(bromoacetamido)propionate). Since crosslinking agents containing a succinimidyl group such as DSS or DSG react with primary amine present at the N-terminus, only the amino group of Xaa2 can be specifically modified with DSS or DSG by blocking the N-terminus and then reacting the peptide with DSS or DSG. For example, a linker (L) may be introduced in advance into the N-terminus of the antibody-modification peptide, and then the reaction with DSS or DSG is performed. The succinimidyl group of DSS or DSG reacts with the Lys252 or Lys254 residue, preferably the Lys254 residue, according to the Eu numbering in an anti-VEGF antibody (e.g., bevacizumab), whereby the anti-VEGF antibody is site-specifically modified with the peptide. These Lys residues are present in the Fc region of human IgG, and even in the case of an anti-VEGF antibody other than bevacizumab, a person skilled in the art can align the amino acid sequence of the antibody and identify the corresponding Lys residue.
Linker (L) is not particularly limited as long as it can link a chelating agent and an antibody-modification peptide in the radioactive conjugate of the present invention. The linker (L) used in the present invention is not particularly limited as long as it does not contain a thiourea bond and examples thereof include substituted or unsubstituted alkyl group, substituted or unsubstituted heteroalkyl group, polyethylene glycol (PEG) group, peptide, sugar chain, disulfide group, amide group, combination of these and the like.
In the present specification, linker (L) is a general term for linkers used for the connection of an anti-VEGF antibody modified with an antibody-modification peptide and a chelating agent, and includes antibody-modification linker (L)) and chelate linker (L). The antibody-modification linker (L), which is described in detail later, is to be introduced into the N-terminal side of the antibody-modification peptide described in (1-4), and the chelate linker (L2), which is described in detail later, is to be introduced into the functional group of the chelating agent described in (1-3).
The linker (L) used in the present invention may contain a binding site formed by a click reaction, and preferably, the antibody-modification linker (L) and the chelate linker (L2) are bound by a click reaction. In the present invention, it is preferred that a thiourea bond is not present between the binding site formed by the click reaction and the chelating agent. In other words, it is preferred that the chelate linker (La) does not contain a thiourea bond. Here, the binding site formed by a click reaction is preferably a triazole skeleton-containing structure represented by the following formula (10a) or (10b) or a pyridazine skeleton-containing structure represented by the following formula (10c) can be considered. Since the formula (10a) and the formula (10b) are isomers, they may be contained at any ratio.
In the formula (10a) and the formula (10b), R1A is a linkage site with a chelating agent, and R2A is a linkage site with an antibody modification peptide. In the formula (10c), one of R3A and R4A is a hydrogen atom, a methyl group, a phenyl group or a pyridyl group, and the other is a binding site with a chelating agent, and R5A is a binding site with an antibody-modification peptide. In the formula (10a), the formula (10b) and the formula (10c), the linkage site with the antibody-modification peptide is linked with the peptide via the antibody-modification linker (L), and the linkage site with the chelating agent is linked with the chelating agent via the chelate linker (L2).
In the radioactive conjugate of the present invention, the antibody is site-specifically modified with an antibody-modification peptide, and the peptide and a chelating agent are linked via a linker (L). Thus, one molecule or two molecules of the chelating agent are conjugated to one molecule of the anti-VEGF antibody.
The production method of the radioactive conjugate of the present invention includes two steps which are a conjugation step of conjugating a chelating agent and an anti-VEGE antibody, and a complex formation step of forming a complex of a metal radionuclide and a chelating agent. The conjugation step may be performed before the complex formation step or after the complex formation step.
In the conjugation step, the Fc region of an antibody is site-specifically modified with a chelating agent or linker (L) having the antibody-modification peptide represented by the aforementioned formula (i).
In the complex formation step, the chelating agent is chelated with a metal radionuclide (complex formation). The metal radionuclide used here is preferably used in a manner permitting ionization, more preferably in the form of an ion, from the viewpoint of increasing the complex formation efficiency. In the complex formation step, the order of addition of the metal radionuclide to the chelating agent does not matter as long as a complex can be formed with the metal radionuclide. For example, a solution in which radioactive metal ion is dissolved in a solvent mainly composed of water can be used as a radionuclide.
After complex formation, the obtained complex may be purified using a filtration filter, a membrane filter, a column filled with various fillers, chromatography or the like.
In the production method of the radioactive conjugate of the present invention, a conjugation step is preferably performed after the complex formation step.
In a more preferred embodiment, in complex formation step (A), a complex is formed between a metal radionuclide and a chelating agent having a first atomic group capable of click reaction as a substituent for enabling conjugation with the antibody. Then, in conjugation step (B), using an antibody-modification peptide shown by the aforementioned formula (i) and an antibody-modification linker (L) having a second atomic group capable of click reaction, a click reaction is performed between the peptide-modified antibody in which Fc region is site-specifically modified and the chelating agent with a formed complex which is obtained in step (A) to obtain the radioactive conjugate of the present invention.
The steps (A) and (B) are described in detail below.
As the combination of the first atomic group and the second atomic group capable of click reaction, an appropriate combination is selected according to the type of the click reaction. For example, a combination of alkyne and azide, a combination of 1,2,4,5-tetrazine and alkene, and the like can be mentioned. In these atomic groups, the first atomic group has one of the above-mentioned atomic group combination, and the second atomic group has one atomic group which is different from the first atomic group of the above-mentioned atomic group combination. To achieve both the stability of the chelating agent and the antibody and the improvement of the binding efficiency thereof, the chelate linker (L2) is preferably alkyne and the antibody-modification linker (L1) is preferably azide, or the chelate linker (L2) is preferably 1,2,4,5-tetrazine and the antibody-modification linker (L1) is preferably alkene. Specific examples of the click reaction by such combinations of atomic groups include a Husgen cyclization addition reaction, an inverse electron-requested Diels-Alder reaction, and the like.
Specific examples of the combination of the atomic groups capable of click reaction include, as shown in the following formulas, a combination of an atomic group containing dibenzylcyclooctyne (DBCO) as alkyne of the first atomic group (the formula (1a)) and an atomic group containing an azide group as azide of the second atomic group (the formula (2a)), or a combination of an atomic group containing 1,2,4,5-tetrazine as the first atomic group (the formula (1b)) and an atomic group containing trans-cyclooctene (TCO) as alkene of the second atomic group (the formula (2b)). Preferred is the combination of the formula (1a) and the formula (2a).
In the formula (1a), R1 is a linkage site with a chelating agent, and in the formula (2a), R2 is a linkage site with an antibody-modification peptide.
In the formula (1b), one of R3 and R4 is a linkage site with a chelating agent or an antibody-modification peptide, and the other is a hydrogen atom, a methyl group, a phenyl group or a pyridyl group. When the atomic group of the formula (1b) is linked with a chelating agent, R5 is the linkage site with the antibody-modification peptide, and when the atomic group of the formula (1b) is linked with an antibody-modification peptide, R5 is the linkage site with the chelating agent.
When an atomic group containing dibenzylcyclooctyne (DBCO) represented by the above-mentioned formula (1a) as alkyne of the first atomic group is used, various commercially available DBCO reagents can be mentioned. Specifically, for example, DBCO-C6-Acid, Dibenzylcyclooctyne-Amine, Dibenzylcyclooctyne Maleimide, DBCO-PEG acid, DBCO-PEG-Alcohol, DBCO-PEG-amine, DBCO-PEG-NH-Boc, Carboxyrhodamine-PEG-DBCO, Sulforhodamine-PEG-DBCO, TAMRA-PEG-DBCO, DBCO-PEG-Biotin, DBCO-PEG-DBCO, DBCO-PEG-Maleimide, TCO-PEG-DBCO, DBCO-mPEG and the like can be selected, and Dibenzylcyclooctyne Maleimide is preferably used.
In the complex formation step (A), it is more preferred to use a compound having a structure represented by the following formula (ii):
A-B—C (ii)
In the formula (ii), A is the aforementioned chelating agent, and the generic term for B and C is a chelate linker (L2).
In the formula (ii), B is represented by the following formula (iib)
In the formula (iib), La and Lb are each independently a bond linker containing at least an amide bond and not less than 1 and not more than 50 carbon atoms, t is an integer of not less than 0 and not more than 30, s is 0 or 1, * is a binding site with A, and ** is a binding site with C.
In the formula (ii), C is either an alkyne derivative represented by the following formula (iic) or a tetrazine derivative represented by the formula (iid).
In the formula (iic), X is CHRk-** or N—**, Y is CHRk or C═O, Rk is independently a hydrogen atom or an alkyl group having not less than 1 and not more than 5 carbon atoms, when X is CHRk-** and Y is CHRk, then Rk moieties may be joined to form a cycloalkyl group, Rf, Rg, Rh and Ri are each independently a hydrogen atom, a halogen atom, or an alkyl group having not less than 1 and not more than 5 carbon atoms, Rf and Rg may be joined, or Rh and Ri may be joined to form a hydrocarbocycle, ** is a binding site with B, in the formula (iid), ** is a binding site with B, and Rj is a hydrogen atom, a methyl group, a phenyl group or a pyridyl group.
As the chelating agent used in step (A), a DOTA derivative of the above-mentioned formula (A) wherein R11 to R14 are —(CH2)pCOOH, p is 1, R15 is a binding site with B; or DO3A derivative or DOTAGA derivative wherein R11 to R14 are —(CH2)pCOOH, p is 1, R12 is a binding site (*) with B, and R15 is a hydrogen atom is more preferred.
In the formula (ii), a DO3A-PEGt-DBCO wherein A is the above-mentioned DO3A, in B, La is a bond linker containing an amide bond and having not less than 1 and not more than 50 carbon atoms, s is 0 or 1, when s is 1, t is an integer of not less than 0 and not more than 30, Lb is a bond linker containing an amide bond and having not less than 1 and not more than 50 carbon atoms, and C is an alkyne derivative represented by the formula (iic), wherein, in the formula (iic), X is N—**, Y is CHRk, Rk is a hydrogen atom, Rf and Rg are jointed to form a benzene ring, Rh and Ri are jointed to form a benzene ring, and ** is a binding site with B is preferred.
In the formula (ii) a DOTAGA-PEGt-DBCO derivative wherein A is the above-mentioned DOTAGA derivative, in B, La is a bond linker containing an amide bond and having not less than 1 and not more than 50 carbon atoms, s is 0 or 1, when s is 1, t is an integer of not less than 0 and not more than 30, Lb is a bond linker containing an amide bond and having not less than 1 and not more than 50 carbon atoms, and C is an alkyne derivative represented by the formula (iic), wherein, in the formula (iic), X is N—**, Y is CHRk, Rk is a hydrogen atom, Rf and Rg are jointed to form a benzene ring, Rh and Ri are jointed to form a benzene ring, and ** is a binding site with B is preferred. It is more preferably the following DOTAGA-DBCO.
In the molar ratio of the chelating agent and metal radionuclide, as chelate site/metal radionuclide, the lower limit is preferably not less than 10/1, more preferably not less than 100/1, further preferably not less than 500/1, and the upper limit is preferably not more than 10000/1, more preferably not more than 8000/1, further preferably not more than 7000/1. For example, the range of not less than 100/1 and not more than 7000/1 is preferred, and not less than 500/1 and not more than 7000/1 is more preferred.
The complex formation reaction is preferably performed in a solvent. As the solvent, water, saline, buffers such as sodium acetate buffer, ammonium acetate buffer, phosphate buffer, phosphate buffered saline, tris hydroxymethylaminomethane buffer (Tris buffer), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer (HEPES buffer), tetramethylammonium acetate buffer, and the like can be used.
While the amount of the solvent is not particularly limited, from the aspect of practicality in the production step, the lower limit at the start of step (A) is not less than 0.01 mL, preferably not less than 0.1 mL, more preferably not less than 1.0 mL, further preferably not less than 10 mL, further more preferably not less than 100 ml, and upper limit is preferably not more than 1000 mL, more preferably not more than 100 ml, further preferably not more than 10 mL, further more preferably not more than 1.0 mL. For example, it is within the range of not less than 0.01 mL and not more than 100 mL.
As the concentration of the chelating agent in the reaction mixture of the complex formation reaction, from the aspect of the yield of the desired chelating agent, the lower limit at the start of step (A) is each independently preferably not less than 0.001 μmol/L, more preferably not less than 0.01 μmol/L, further preferably not less than 0.1 μmol/L, more preferably not less than 1 μmol/L, and the upper limit is preferably not more than 1000 μmol/L, more preferably not more than 100 μmol/L, further preferably not more than 10 μmol/L. For example, it is within the range of not less than 1 μmol/L. and not more than 100 μmol/L.
The temperature of the complex formation reaction may be, for example, room temperature (25° C.) or under heating conditions. To simultaneously achieve suppression of decomposition of the chelating agent and improvement of complex formation efficiency, the lower limit is preferably not less than 20° C., more preferably not less than 30° C., further preferably not less than 35° C., further more preferably not less than 37° C., particularly preferably not less than 45° C. The upper limit is preferably not more than 150° C., more preferably not more than 120° C., further preferably not more than 100° C., further more preferably not more than 90° C. For example, a range of not less than 30° C. and not more than 100° C. is preferred, and a range of not less than 35° C. and not more than 90° C. is more preferred.
The antibody to be used in step (B) is a peptide-modified antibody in which Fc region (constant region) of anti-VEGF antibody as described in detail in the above-mentioned “(1-2) Antibody” is site-specifically modified using the antibody-modification peptide shown in the aforementioned formula (i), and an antibody-modification linker (L2) having the second atomic group capable of click reaction.
The antibody-modification peptide can be produced using a combination of amino acids regardless of natural amino acids and unnatural amino acids, by subjecting to peptide synthesis methods such as liquid phase synthesis process, solid phase synthesis process, automatic peptide synthesis method, gene recombinant method, phage display method and the like. In the synthesis of the peptide, where necessary, the functional groups of the amino acids to be used may be protected. These methods can be performed according to the method described in, for example, WO 2017/217347 and WO 2018/230257.
The antibody-modification linker (L2) may be one in which an antibody-modification peptide and a linker (L2) represented by the following formula (S1) are bonded.
*-((Li)m-Z)k-Lii-AG2 (S1)
wherein * is a binding site with the N-terminal or C-terminal of peptide,
In the aforementioned formula (S1), the structure of Z is not particularly limited as long as it is a linker structure that binds (Li)m and Lii to each other, and includes, for example, an amino acid sequence consisting of not less than 1 and not more than 5 amino acid residues. In this case, the amino acid sequence contained in Z preferably contains a cysteine residue, and is more preferably bonded to L2 via a thioether group formed by the bond between the thiol group of the cysteine residue and a maleimide group.
In the present invention, the polyethylene glycol (PEG) linker moiety constituting Lii preferably has the structure shown by the following formula (P2). In the formula (P2), n is an integer of preferably not less than 1 and not more than 50, more preferably not less than 1 and not more than 20, further preferably not less than 2 and not more than 10, further more preferably not less than 2 and not more than 6.
One end of the structure of the PEG linker moiety may be modified by a structure derived from a commercially available PEGylation reagent or a structure derived from a reagent generally used for PEGylation. Although not particularly limited, examples thereof include structures derived from diglycolic acid or a derivative thereof, and maleimide or a derivative thereof.
As a method for introducing the aforementioned second atomic group into an antibody-modification linker (L2), an introduction method including obtaining an antibody-modification peptide having a desired amino acid sequence by the aforementioned method, dissolving the peptide in a solution containing a solubilizing agent and a reducing agent and where necessary, an acid, adding an organic solvent solution of an atomic group containing an azide group or trans-cyclooctene (TCO) as the second atomic group to the solution, and stirring the mixture at room temperature can be mentioned.
When an atomic group containing an azide group is introduced as the second atomic group, the azide group is directly introduced into the N-terminal or C-terminal of a peptide by using a commercially available azide group-introducing reagent according to a conventional method, or an atomic group containing an azide group can be introduced via the aforementioned linker structure. Examples of the azide group-introducing reagent to be used include silyl azide, azide phosphate, alkyl ammonium azide, inorganic azide, sulfonyl azide, PEG azide, and the like.
When an atomic group containing TCO is introduced as the second atomic group, TCO is directly introduced into the N-terminal or C-terminal of a peptide by using a commercially available click chemistry reagent containing TCO according to a conventional method, or an atomic group containing TCO can be introduced via the aforementioned linker structure.
The method for binding an antibody-modification peptide to an anti-VEGF antibody to obtain a peptide-modified antibody can be performed, for example, by dispersing the aforementioned antibody-modification peptide, an anti-VEGF antibody, a crosslinking agent, and a catalyst as necessary in an appropriate buffer, according to the description of WO 2017/217347. As the crosslinking agent, those mentioned above can be used. In addition, when binding the antibody-modification peptide and the anti-VEGF antibody, where necessary, buffer replacement including treating the solution containing the anti-VEGF antibody with an ultrafiltration filter, etc., and dispersing same in a buffer may be performed once or twice before binding with the antibody-modification peptide.
In one embodiment, the present disclosure relates to a method for producing a conjugate of an antibody-modification peptide and an anti-VEGF antibody, including a step of mixing an antibody-modification peptide modified with a crosslinking agent and an anti-VEGF antibody. By this step, a crosslinking reaction can occur between the antibody-modification peptide modified with a crosslinking agent and an anti-VEGF antibody (e.g., bevacizumab). The crosslinking reaction can occur site-specifically between the above-mentioned amino acid residue Xaa2 of the antibody-modification peptide and the Lys252 or Lys254 residue, preferably the Lys254 residue, according to Eu numbering in human IgG Fc.
The conditions of the mixing step are not particularly limited as long as a crosslinking reaction occurs between the antibody-modification peptide and the anti-VEGF antibody. For example, the reaction can be performed by mixing the antibody-modification peptide and the anti-VEGF antibody in an appropriate buffer at room temperature (e.g., about 15° C. to 30° C.). The mixing step may be performed by adding as necessary an appropriate amount of a catalyst that promotes the crosslinking reaction.
In one embodiment, a solvent containing at least water is added to dissolve the anti-VEGF antibody. The solvent other than water includes, for example, dimethyl sulfoxide, acetonitrile, saline, and buffers such as sodium acetate buffer, ammonium acetate buffer, phosphate buffer, phosphate buffered saline, Tris buffer, HEPES buffer, tetramethylammonium acetate buffer, histidine buffer, and the like. When a buffer is used, the pH at 25° C. is preferably set to 4.0 or more and 10.0 or less, more preferably 5.5 or more and 8.5 or less, from the aspect of the stability of the antibody. At the start of the crosslinking reaction, the concentration of the antibody is preferably set to 1.0 μmol/L or more as the lower limit and 1000 μmol/L or less, more preferably 500 μmol/L or less, as the upper limit.
Then, an antibody-modification peptide modified with a crosslinking agent and, where necessary, a catalyst are added and the mixture is dispersed at 10° C. or higher and 30° C. or lower.
The mixing ratio of the antibody-modification peptide and the anti-VEGF antibody in the mixing step is not particularly limited. The molar ratio of the antibody-modification peptide and the anti-VEGF antibody can be set to, for example, 1:1 to 20:1, preferably 2:1 to 20:1 or 5:1 to 10:1.
In a preferred embodiment, antibody-modification peptide can be mixed with the anti-VEGF antibody at 0.5 to 2.2, preferably 0.8 to 1.8, (molar ratio) in the above-mentioned mixing step. In this case, an antibody in which one molecule of the antibody-modification peptide is bound to one anti-VEGF antibody molecule (hereinafter referred to as a “monovalent antibody”) can be efficiently obtained.
The mixing time (reaction time) in the mixing step is not particularly limited as long as a crosslinking reaction occurs between the antibody-modification peptide and the anti-VEGF antibody. It is, for example, 1 min to 5 hr, preferably 10 min to 2 hr.
The peptide-modified antibody obtained through the above steps is a mixture containing an antibody in which one molecule of antibody-modification peptide is bound to one molecule of anti-VEGE antibody (i.e., “monovalent antibody”) and an antibody in which two molecules of antibody-modification peptide are bound to one molecule of anti-VEGF antibody (hereinafter referred to as “divalent antibody”) at any ratio. This may be used as it is for the subsequent steps, or an unmodified antibody, a monovalent antibody, and a divalent antibody are separated and purified by a method such as filtration filter, membrane filter, column filled with various fillers, various chromatographies and the like, and only the antibody having any valence may be subjected to the subsequent steps. When the unmodified antibody cannot be separated from the antibody having other valence as a result of purification, a mixture containing these may be subjected to the subsequent steps.
When an unmodified antibody, a monovalent antibody, and a divalent antibody are separated and purified, any of the above-mentioned purification methods may be used for separation and purification. It is possible to use a column filled with various fillers. For example, a column filled with a filler in which a protein such as protein A, protein G, or the aforementioned antibody-modification peptide is bound to a carrier can be used. The shape of the carrier of the filler filled in such a column includes gel (e.g., column gel), particle, bead, nanoparticle, microparticle, macrobead, and the like. The materials of the carrier include magnetic substance, latex, agarose, glass, cellulose, sepharose, nitrocellulose, polystyrene, and other polymeric materials. Specific example is an IgG-BP column in which the aforementioned antibody-modification peptide is bound to a column gel (see WO 2021/080008).
The IgG-BP column is a column immobilized with an IgG-binding peptide. Divalent antibody cannot bind to the column because the binding sites are already occupied by the IgG-binding peptide, and only monovalent antibodies show affinity to the column. Using the IgG-BP column and utilizing the difference in the interaction with respective antibody-modification peptides, the first antibody composition containing relatively large amounts of the unmodified antibody and the monovalent antibody and the second antibody composition containing a relatively large amount of the divalent antibody can be respectively separated and purified. In one preferred embodiment, the molar ratio of unmodified antibody to monovalent antibody in the first antibody composition is 4-47:53-96, preferably 4-30:70-96, more preferably 4-20:80-96, further preferably 4-10:90-96.
In this way, the first antibody composition or the second antibody composition separated and purified may be used as it is for the click reaction in the subsequent step (B), or may be used for the click reaction in step (B) after adjusting the protein concentration of the peptide-modified antibody contained.
The click reaction in step (B) is performed between the first atomic group capable of click reaction which is contained in the chelating agent, and the second atomic group capable of click reaction which is contained in the peptide-modified antibody. By such click reaction, a binding group (substituent capable of conjugating with antibody) that links a chelating agent and an antibody is formed.
When the peptide-modified antibody and the complex obtained in step (A) are capable of click reaction, the order of addition of these does not matter. For example, one of the complex and the peptide-modified antibody is added to a reaction container containing a solvent, and then the other is added to perform the reaction, or one of the chelating agent and the antibody is dispersed in a solvent and the other is added to the dispersion to perform the reaction. Alternatively, these may be simultaneously added to a reaction container containing a solvent to perform the reaction.
As the solvent to be used for the click reaction in step (B), a solvent containing water can be used. For example, water, saline, buffers such as sodium acetate buffer, ammonium acetate buffer, phosphate buffer, phosphate buffered saline, Tris buffer, HEPES buffer, tetramethylammonium acetate buffer and the like, and the like can be used. When a buffer is used, to simultaneously achieve the stability of the complex and the antibody, and the bond efficiency of these, the pH at 25% is preferably set to not less than 4.0 and not more than 10.0, further preferably not less than 5.5 and not more than 8.5.
While the amount of the reaction mixture is not particularly limited, from the aspect of practicality in the production step, at the start of step (B), the lower limit is preferably not less than 0.001 mL, more preferably not less than 0.01 mL, further preferably not less than 0.1 mL, further more preferably not less than 1 mL, and the upper limit is preferably not more than 1000 ml, more preferably hot more than 100 mL, further preferably not more than 10 mL, further more preferably not more than 1 mL. For example, the range of not less than 0.001 mL and not more than 1000 mL is preferable, and the range of not less than 0.1 mL and not more than 10 mL is more preferable.
As the concentrations of the chelating agent and the antibody in the reaction mixture, each independently, at the Start of step (B), the lower limit is preferably not less than 0.001 μmol/L, more preferably not less than 0.01 μmol/L, further preferably not less than 0.1 μmol/L, further more preferably not less than 1.0 μmol/L, and the upper limit is preferably not more than 1000 μmol/L, more preferably not more than 100 μmol/L. For example, the range of not less than 0.1 μmol/L and not more than 1000 μmol/L is preferable, and the range of not less than 1 μmol/L and not more than 100 μmol/L is more preferable, from the aspect of the yield of the desired conjugate.
To prevent unintended denaturation of the antibody and increase the reaction efficiency, the upper limit of the reaction temperature of the click reaction in step (B) is preferably not more than 50° C., more preferably not more than 40° C. The lower limit of the reaction temperature is not particularly limited as long as the reaction proceeds, and is preferably not less than 15° C. The reaction time of the click reaction is, on the condition that it is the aforementioned reaction temperature, preferably not less than 5 min, more preferably not less than 10 min, preferably not more than 24 hr, more preferably not more than 20 hr. For example, the range of not less than 5 min and not more than 24 hr is preferable, and the range of not less than 10 min and not more than 20 hr is more preferable.
The obtained conjugate may be used as it is or purified using a filtration filter, a membrane filter, a column filled with various fillers, chromatography or the like.
In the conjugate produced by steps (A) and (B), the lysine residue in the Fc region of anti-VEGF antibody is specifically modified with a chelating agent. This conjugate comprises one or two molecules of the aforementioned chelating agent per one molecule of the antibody. The chelating agent site-specifically modifies the Fc region of the antibody of the present invention via a linker (L). The linker (L) is constituted of a chelate linker (L) that connects to a chelating agent, a first atomic group that connects to the linker (L2), a second atomic group that can perform click reaction with the first atomic group, and an antibody-modification linker (L)) that connects to the second atomic group (including an antibody-modification peptide represented by the above-mentioned formula (i)). Therefore, the linker (L) has a chemical structure derived from the first atomic group and the second atomic group. As such chemical structure, a triazole skeleton-containing structure represented by the aforementioned formula (10a) or (10b) or a pyridazine skeleton-containing structure represented by the aforementioned formula (10c) can be considered, Since the formula (10a) and the formula (10b) are isomers, they may be contained at any ratio.
A radiopharmaceutical refers to a composition that contains the radioactive conjugate of the present invention and is in a form suitable for in vivo administration to a subject. The radiopharmaceutical may be, for example, a radioactive conjugate produced by the method shown in the aforementioned (1-6) as it is, or can be produced by purifying same and dissolving same in a solvent mainly containing water and approximately isotonic with the living body. In this case, the radiopharmaceutical is preferably in the form of an aqueous solution, and may contain other pharmaceutically acceptable components as necessary. An effective amount of the radiopharmaceutical is orally or parenterally, for example, intravenously, subcutaneously, intraperitoneally, intramuscularly, or the like, administered to a living body, and is used for treatment of cancer, diagnosis of cancer, detection of a lesion, or the like.
As used herein, the subject of administration is a human, or an animal such as mouse, rat, monkey, guinea pig, chimpanzee, sheep, goat, dog, cat, swine, bovine, horse or the like, but is not particularly limited. Preferred is a human.
A preferred target disease is, VEGF-positive cancer. The type of VEGF-positive cancer to be treated, diagnosed or detected by the present invention is not particularly limited as long as it expresses VEGF, and examples thereof include lung cancer, colorectal cancer, hepatocellular carcinoma, breast Cancer, ovarian cancer, cervical cancer and malignant glioma. In addition, the cancer in which VEGF is expressed may be cancer at any stage, and may be either localized or metastatic, or primary or recurrent. As used herein, the “expression” refers to a state in which the VEGF gene in tumor tissue is significantly amplified as compared with non-tumor tissue, or the expression of VEGF protein is significantly enhanced as compared with non-tumor tissue, when measured by a known test method.
As used herein, the “effective amount” is an amount that can afford useful diagnostic or therapeutic effects in a subject of administration. The effective amount to be administered to a subject varies depending on the type of subject, body weight of the subject, dosage form of administration (tablet, injection, etc.) and route (oral administration, parenteral administration, etc.) of administration, severity of disease (e.g., cancer), and the like. Physicians and veterinarians can consider these factors and determine the appropriate effective amount.
The radiopharmaceutical of the present invention, when stored at room temperature, has radiochemical purity of not less than a given level when a time period of not less than 1 and not more than 5 times the half-life has passed, based on the half-life of the metal radionuclide constituting the radiopharmaceutical. When the above-mentioned metal radionuclide is a β-ray nuclide (e.g., Lu-177 or Y-90), the radiochemical purity of the conjugate when stored at room temperature for 7 days from the end of production is preferably not less than 90%, more preferably not less than 95%. When the metal radionuclide is an α-ray nuclide (e.g., Ac-225), the radiochemical purity of the conjugate when stored at room temperature for 14 days from the end of production is preferably not less than 90%, more preferably not less than 95%.
A specific embodiment of the radiopharmaceutical of the present invention contains a conjugate of a chelating agent to which metal radionuclide is chelated and an anti-VEGF antibody as an active ingredient, does not include a thiourea bond in the linking between the anti-VEGF antibody and the chelating agent (particularly linking via linker (L)), and, when stored at room temperature, has radiochemical purity of not less than a given level when a time period of not less than 1 and not more than 5 times the half-life has passed, based on the half-life of the metal radionuclide constituting the radiopharmaceutical. When the above-mentioned metal radionuclide is a β-ray nuclide (e.g., Lu-177 or Y-90), the radiochemical purity of the aforementioned conjugate when stored at room temperature for 7 days from the end of production is preferably not less than 90%, more preferably not less than 95%. When the metal radionuclide is an α-ray nuclide (e.g., Ac-225), the radiochemical purity of the conjugate when stored at room temperature for 14 days from the end of production is preferably not less than 90%, more preferably not less than 95%.
In the present specification, the “room temperature” preferably refers to “normal temperature” as defined in the Japanese Pharmacopoeia, and is specifically 15 to 25° C.
As used herein, the radiochemical purity refers to the percentage of the radioactivity (counts) of the peak corresponding to the conjugate relative to the total radioactivity (counts) detected when a sample is analyzed with a commercially available radiation detector. While high performance liquid chromatography or thin layer chromatography can be used to analyze radiochemical purity, thin layer chromatography is preferably used. More preferably, thin layer chromatography is used under the conditions described in the Examples below.
As mentioned above, the radiopharmaceutical of the present invention is preferably in the form of an aqueous solution. From the aspect of maintaining the radiochemical purity, it is more preferably in the form of a buffer solution. As the buffer solution, any buffer solution used in antibody drugs containing an anti-VEGF antibody or an ADC of an anti-VEGF antibody as an active ingredient can be used. As a non-limiting example, a phosphate buffer solution, a succinate buffer solution, or a citrate buffer solution can be used. The phosphate buffer solution is composed of phosphoric acid and a salt thereof, and can be composed of, for example, phosphoric acid and a sodium salt thereof. The succinate buffer solution is composed of succinic acid and a salt thereof, and can be composed of, for example, succinic acid and a sodium salt thereof. The citrate buffer solution is composed of citric acid and a salt thereof, and can be composed of, for example, citric acid and a sodium salt thereof. The radiopharmaceutical of the present invention may contain any sugar such as trehalose, sucrose and the like, any amino acid such as histidine and the like, or a solubilizer such as polysorbate 20, polysorbate 80 and the like.
The radiopharmaceutical of the present invention can be used for radionuclide therapy of cancer by selecting metal radionuclides that have a therapeutic effect, specifically radionuclide that emits α rays or nuclide that emits β rays (preferably Ac-225, Y-90, Lu-177, more preferably Ac-225). In this radionuclide therapy, the radiopharmaceutical of the present invention is administered intravenously or orally to cause accumulation of the radioactive conjugate of the present invention in a lesion site such as a cancer primary lesion or metastatic lesion, and cancer cells at the lesion site are destroyed by the radiation emitted from the metal radionuclide. The amount of radioactivity to be administered and dose of the radiopharmaceutical of the present invention is appropriately determined by the efficacy of the active ingredient, the mode and route of administration, the stage of cancer progression, the body shape, body weight and age of the patient, and the type and amount of the therapeutic drug used in combination for other diseases.
In addition, by selecting a radionuclide that emits positron or a radionuclide that emits γ rays (preferably Ga-68, Zr-89, In-111) as the metal radionuclide, it can be used for cancer diagnosis or lesion detection. A radiopharmaceutical using radionuclide that emits positron can be preferably used for PET (Positron Emission Tomography) Scan, and a radiopharmaceutical using radionuclide that emits γ-rays can be preferably used for SPECT (Single Photon Emission Computed Tomography) Scan. This may also be used in combination with cancer diagnosis or lesion detection in the aforementioned radionuclide therapy of cancer. The diagnostic radiopharmaceutical for cancer of the present invention may be used for diagnosis before performing radionuclide therapy for cancer, or may be used for diagnosis after performing radionuclide therapy for cancer. Using the diagnostic radiopharmaceutical before conducting a radionuclide therapy for cancer, selection of treatment can be performed based on whether or not to perform radionuclide therapy for cancer using the radiopharmaceutical of the present invention provided with a radionuclide that emits α-rays. Using the diagnostic radiopharmaceutical after conducting a radionuclide therapy for cancer, moreover, whether or not radionuclide therapy for cancer using the radiopharmaceutical of the present invention is effective can be judged, and a treatment plan including an increase or a decrease of dose and the like can be optimized.
The following embodiments are also encompassed in the technical idea of the present invention.
(X)-Xaa1-(Xb)-Xaa2-(Xc)-Xaa3-(Xd) (i)
The present invention is explained in detail in the following by referring to Examples. The present invention is not limited to such Examples.
A peptide containing 17 amino acid residues represented by the following formula (P3) was obtained by the method described in WO 2017/217347. The amino acid sequence of this peptide was the same as the sequence in which Xaa2 of SEQ ID NO: (2) was a lysine residue, and the side chain terminal amino group of the lysine residue was modified with the structure shown by R1. In addition, two cysteine residues form a disulfide bond with each other, and to the N-terminal of the peptide was added ethyl azide as an atomic group containing an azide group, which is the second atomic group, via a linker (L1) structure having diglycolic acid and eight PEGs.
In the formula (P3), Gly is glycine, Pro is proline, Asp is aspartic acid, Cys is cysteine, Ala is alanine, Tyr is tyrosine, Lys is lysine, His is histidine, Glu is glutamic acid, Leu is leucine, Val is valine, Trp is tryptophan, Thr is threonine, and Phe is phenylalanine.
A mixture of the aforementioned peptide and bevacizumab (manufactured by Roche) in 0.02 mol/L acetic acid sodium acetate buffer (pH 6.0) was reacted at room temperature for 60 min to give a solution containing a peptide-modified antibody. An Fc region of the peptide-modified antibody is site-specifically modified by the above-mentioned peptide.
Then, the solution was passed through an IgG-BP column to obtain a first antibody composition containing unlabeled antibodies and monovalent antibodies in relatively large amounts. The concentration was adjusted with a preservation buffer (mixed solution of 60 g/L trehalose and 5.8 g/L sodium dihydrogen phosphate monohydrate, anhydrous sodium monohydrogen phosphate, 0.4 g/L polysorbate 20) such that the concentration of the monovalent antibody contained in the recovered fraction was 14.6 mg/mL. The solution containing the obtained first antibody composition was subjected to the labeling step described below.
DOTAGA-DBCO represented by the following formula was produced based on the method described in Bernhard et al. DOTAGA-Anhydride: A Valuable Building Block for the Preparation of DOTA-Like Chelating Agents, Chem. Eur. J. 2012, 18, 7834-7841. This chelating agent was dispersed in 0.1 mol/L sodium acetate buffer (pH 5.0) as a solvent to give a dispersion containing 0.3 mmol/L chelating agent. A reaction mixture of the dispersion (0.028 mL) and 225Ac ion-containing solution (0.1 mol/L aqueous hydrochloric acid solution, radioactivity concentration 237.6 MBq/mL, prepared from one produced by State Atomic Energy Corporation Rosatom, liquid amount 0.0126 mL) about 2.99 MBq (Calculated value corrected for attenuation from the amount of radioactivity at the time of the inspection) as a radioactive metal source was reacted under heating conditions to give a 225Ac complex solution. The molar ratio of the chelating agent and the radioactive metal ion was chelating agent: 225Ac ion=about 1350:1, and the heating temperature of the reaction mixture was set to 70° C., and the heating time was set to 30 min.
The radiochemical purity (RCP, %) of the obtained 225AC complex was measured by the following method. That is, a part of the 255Ac complex solution was developed by thin layer chromatography (Agilent, model number: SGI0001, developing solvent:acetonitrile/water mixture (volume ratio 1:1)), and then measured by a radio γ-TLC analyzer (Raytest, Model GITA Star). The percentage of the peak radioactivity (counts) detected near the point of origin relative to the total detected radioactivity (counts) was taken as the RCP of the 225Ac complex. As a result, the RCP of the 225Ac complex was 79%. The obtained 225Ac complex solution was used as it was in the labeling step.
A solution containing the peptide-modified antibody (monovalent antibody) obtained in the above-mentioned step (1) was added to the solution of the unpurified 225Ac complex obtained through the aforementioned step (2), and a click reaction was performed at 37° C. for 120 min to obtain 225Ac-CCAP-bevacizumab1. The amount of the 225Ac complex and the amount of the peptide-modified antibody (monovalent antibody) were 8.7 nmol and 10.2 nmol, respectively, and the molar ratio of the DBCO group to the azide group was about 1:1.2, respectively. The reaction rate (%) of the unpurified 225Ac-CCAP-bevacizumab1 was 72%. As used herein, the reaction rate (%) means the RCP of 225Ac-CCAP-bevacizumab1 relative to the labeling rate (%) in the complex formation step, and the labeling rate (%) means the ratio (%) of the radioactivity of the 225Ac complex to the input radioactivity.
Furthermore, the solution of 225Ac-CCAP-bevacizumab1 obtained by reacting at 37° C. for 2 hr was purified using an ultrafiltration filter (Merck, model number: UFC505096). After purification, the radiochemical yield (RCY, %) of 225Ac-CCAP-bevacizumab1 was 70%, and RCP was 97%.
The reaction rate, RCP, and RCY of 225Ac-CCAP-bevacizumab1 were measured as follows. That is, thin layer chromatography (Agilent, model number: SGI0001, developing solvent was a mixture of acetonitrile: 0.1 mmol/L EDTA solution (volume ratio 1:1)) was measured with a radio-γ-TLC analyzer (Raytest, MODEL GITA Star). The percentage of the peak radioactivity (counts) detected near the point of origin relative to the total radioactivity (counts) detected was taken as RCP (%), which was divided by the labeling rate (%) to calculate the reaction rate (%). Furthermore, the percentage of the radioactivity recovered after ultrafiltration purification (the amount of radioactivity calculated from the counts measured with a γ-ray spectrometer (Ge semiconductor detector: GMX10P4-70 (manufactured by ORTEC), multichannel analyzer: M7-000 (manufactured by Seiko E.G. & G), data processing: Spectrum Navigator: DS-P300 (manufactured by Seiko E.G. & G) and Gamma Studio: DS-P600 (manufactured by Seiko E.G. & G)) relative to the total radioactivity added at the start of the labeling step (the amount of radioactivity calculated from the counts measured with a γ-ray spectrometer in the same manner as above) was defined as RCY (%).
225Ac-CCAP-bevacizumab2 was obtained by an operation according to Example 1, except that DOTAGA-DBCO was replaced with DOTA-Bn-DBCO below. The reaction rate was 50%, RCY was 15%, and RCP was 62%.
A portion of 225Ac-CCAP-bevacizumab1 produced according to the description of Example 1 was taken out into a 5 mL Eppendorf tube (LoBind, manufactured by Eppendorf) and diluted with formulation buffer (mixed solution of 60 g/L trehalose, 5.8 g/L sodium dihydrogen phosphate monohydrate, anhydrous sodium monohydrogen phosphate, and 0.4 g/L polysorbate 20).
The in vitro efficacy of the radioactive conjugate of the present invention was evaluated using the following lung cancer-derived cell lines.
The aforementioned cells were cultured in appropriate media, and 225Ac-CCAP-bevacizumab1 prepared according to the description in Example 3 was diluted with each medium to 0, 0.001, 0.01, 0.03, 0.1, 0.3, 1, 3, 10, and 30 kBq/mL (0.00229, 0.0229, 0.0687, 0.229, 0.687, 2.29, 6.87, 22.9, and 68.7 μg/mL as bevacizumab) and added to the cells. Unlabeled bevacizumab was also added to the cells so that the antibody concentration was the same as that of the samples with each radioactivity concentration, and the cells were cultured. After 120 hr from the addition of the sample, CellTiter-Glo (registered trademark) 2.0 Cell Viability Assay (manufactured by Promega) was added to the medium, and chemiluminescence was detected using a microplate reader (SpectraMax i3x, manufactured by Molecular Devices) to calculate the number of viable cells. The cytotoxic effect was evaluated by calculating the ratio of the calculated number of viable cells to the number of viable cells in the case of the condition in which the antibody was not added.
The results are shown in
A subcutaneous A549 tumor-bearing model was created using mice and the in vivo efficacy of the radioactive conjugate of the present invention was evaluated.
A549 cells, a VEGF-positive cell line derived from human lung adenocarcinoma purchased from ATCC, were suspended in F-12K medium and 5×106 cells were subcutaneously transplanted into the flank of 5-week-old female BALB/c nu/nu mice (manufactured by Jackson Laboratory Japan, Inc.) to create tumor-bearing mice. Tumors were allowed to grow until they reached a volume of 100-300 mm, and mice with a shape suitable for tumor diameter measurement were randomly divided into groups. The tumor volume and body weight of each mouse at 5 that time are shown in Table 1. Tumor volume was calculated according to the following formula.
225Ac-CCAP-bevacizumab1
225Ac-CCAP-bevacizumab1 was administered into the tail vein at a dose of 10 kBq/mouse (60 μg/mouse as bevacizumab) .
Antibody control group, radioactivity control group, and vehicle group were each set as control groups.
The antibody control group was administered with bevacizumab (unlabeled) in the same antibody amount as 225Ac-CCAP-bevacizumab1.
The radioactivity control group was administered with 225Ac-CCAP-human IgG antibody at a dose of 10 kBq/mouse, which was produced in the same manner as in Example 1, except that bevacizumab was replaced with human IgG antibody (InVivoPlus human IgG1 isotype control, manufactured by Bio X cell).
The vehicle group was administered only with the formulation buffer used in Example 3.
Each group was administered at a dose of 100 μL/mouse.
Each group consisted of 5 or 6 mice, and general conditions were observed, and the body weight and tumor volume were measured over time up to 42 days after administration. The change in tumor volume over time is shown in the graph in
The group administered with 225Ac-CCAP-bevacizumab1 showed a significant difference in antitumor effect compared to the radioactive control group and the vehicle group at the 42nd day after administration (P<0.05 and P<0.01). To test for significant difference, a Tukey test was performed using statistical analysis software Stat Preclinica (manufactured by Takumi Information Technology Co., Ltd.). On the other hand, 225Ac-CCAP-bevacizumab1 showed no significant difference in antitumor effect compared to the antibody control group, but showed a tendency toward a stronger antitumor effect. In addition, there was no remarkable change in the general condition of each group, and no signs of toxicity such as remarkable weight loss and the like were observed.
DOTAGA-DBCO was dispersed in 0.1 mol/L sodium acetate buffer (pH 5.0) as a solvent to give a dispersion containing 0.3 mmol/L chelating agent. A reaction solution obtained by mixing 0.1086 mL of this dispersion with 0.0815 mL of a 0.156 mol/L sodium acetate solution containing 0.075 mol/L gentisic acid and 317 MBq of a solution containing 89Zr ions (0.1 mol/L hydrochloric acid aqueous solution, radioactivity concentration 5.76 GBq/mL, prepared from one manufactured by Nippon Medi-Physics Co., Ltd., liquid volume 0.055 mL) as a radioactive metal source was reacted under heating conditions to obtain a 89Zr complex solution. The molar ratio of the chelating agent and the radioactive metal ion was chelating agent: 89Zr ion=about 152:1, and the heating temperature of the reaction mixture was set to 70° C., and the heating time was set to 60 min. The obtained 89Zr complex solution was used as it was in the labeling step. The RCP of the obtained 89Zr complex was measured by the following method. That is, a part of the 89% r complex solution was developed by thin layer chromatography (manufactured by Agilent, model number: SGI0001, developing solvent was acetonitrile:water mixture (volume ratio 1:1)), and then measured by a radio γ-TLC analyzer (manufactured by Raytest, Model GITA Star PS). The percentage of the radioactivity (counts) of the peak detected near the point of origin to the total radioactivity (counts) detected was taken as the RCP (%) of the 89Zr complex. As a result, the RCP of the 89Zr complex was 74%. The obtained 89Zr complex solution was used as it was in the labeling step.
A solution containing the peptide-modified antibody (monovalent antibody) obtained in the same manner as in Example 1 was added to the solution of the unpurified 89Zr complex obtained through the aforementioned step (1) were respectively added unpurified to 0.1 mol/L arginine-containing 0.05 mmol/L histidine buffer (pH 6.1), and a click reaction was performed at 37° C. for 90 min to obtain 89Zr-CCAP-bevacizumab1. The amount of the Zr complex and the amount of the peptide-modified antibody (monovalent antibody) were 32.6 nmol and 24.6 nmol, respectively, and the molar ratio of the DBCO group to the azide group was about 1:0.75, respectively. The reaction rate (%) of the unpurified 89Zr-CCAP-bevacizumab1 was 74%. As used herein, the reaction rate (%) means the RCP of 89Zr complex relative to the labeling rate (%) in the complex formation step, and the labeling rate (%) means the ratio (%) of the radioactivity of the 89Zr complex to the input radioactivity.
Furthermore, the solution of 89Zr-CCAP-bevacizumab1 obtained by reacting at 37° C. for 2 hr was purified using an ultrafiltration filter (Merck, model number: UFC505096). After purification, RCP of 89Zr-CCAP-bevacizumab1 was 96%, and RCY was 62%. RCP and RCY of 89Zr-CCAP-bevacizumab1 were measured as in Example 1.
1.0 mL of each of the radioactive conjugates produced according to the description in Example 4 was dispensed into a 5 mL Eppendorf tube (LoBind, manufactured by Eppendorf) and diluted with 3.64 mL of formulation buffer (mixed solution of 42 g/L trehalose hydrate, 0.47 g/L L-histidine hydrochloride hydrate, 0.30 g/L L-histidine, and 85 mg/L polysorbate 20).
In addition to the cells used in Evaluation 2, the following lung cancer cell line was used to create tumor-bearing mice.
A cell suspension of each cell line was prepared, and 5×106 cells were subcutaneously transplanted into the left front leg of a 5-week-old female BALB/c nu/nu (Charles River Laboratories Japan, Inc.) to create a tumor-bearing mouse. The tumor was allowed to grow until the tumor volume reached about 100-300 mm3, and 89Zr-CCAP-bevacizumab1 was administered into the tail vein at a dose of 6 MBq/mouse (n=3 each). 72 hours after administration, imaging was performed using a small animal PET imaging device (PET/CT Si78, manufactured by Bruker). The PET imaging conditions were Acquisition time of 600 sec and Energy window of 30% (357.7-664.3 keV). Data correction included scatter correction, random correction, attenuation correction, partial volume, and attenuation, and PET image reconstruction was performed using the maximum likelihood-expectation maximization (MLEM) method (Iterations: 12).
Tumor volume was calculated using the following formula:
A representative example of the results of PET imaging is shown in
Radioactivity accumulated at a higher concentration in the tumor as compared with other organs, and VEGF-positive tumor could be visualized.
Each radioactive conjugate (225Ac-CCAP-bevacizumab1 and 225Ac-CCAP-bevacizumab2) produced according to the descriptions in Example 1 and Example 2 and prepared according to the description in Example 3 was stored at room temperature (24.8-24.9° C.) for 2 weeks, and RCP and the proportion of aggregates were evaluated at each time point (0th day, 1st day, 7th day, and 14th day). When the radioactive metal nuclide is 225Ac, the period of 14 days after completion of the production corresponds to about 1.5 half-life
RCP was analyzed by thin layer chromatography (TLC). The TLC conditions were similar to those used when examining the reaction rate in Example 1.
The results are shown in Table 2.
225Ac-CCAP-
225Ac-CCAP-
For 225Ac-CCAP-bevacizumab1, the RCP was maintained at 98% or more when stored at room temperature for 7 days after the completion of the production, and no significant decrease in RCP was observed even when stored for 14 days.
For 225Ac-CCAP-bevacizumab2, the RCP was below 80% when stored at room temperature for 7 days or more after the completion of the production.
The proportion of the aggregates was confirmed by size-exclusion chromatography (SEC). Using Model 2695 Separation Module or e2695 Separation Module, manufactured by Water, as a Liquid chromatography device, and Model 2489 UV/Vis Detector manufactured by Waters as a UV detector, analysis was performed under the following conditions. The proportion of each component when stored for 14 days after completion of the production is shown in Table 3. When stored for 14 days after completion of the production. The proportion of the aggregates was of the same level between 225Ac-CCAP-bevacizumab1 and 225Ac-CCAP-bevacizumab2.
225Ac-CCAP-
225Ac-CCAP-
This application is based on a patent application No. 2022-021663 filed in Japan (filing date: Feb. 15, 2022), the contents of which are incorporated in full herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-021663 | Feb 2022 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2023/004911 | 2/14/2023 | WO |
