Patent Grant
10654887
The instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Nov. 16, 2019, is named 313838A_2_ST25.txt and is 79,651 bytes in size.
The present invention relates to the field of affinity chromatography, and more specifically to mutated immunoglobulin-binding domains of Protein A, which are useful in affinity chromatography of immunoglobulins. The invention also relates to multimers of the mutated domains and to separation matrices containing the mutated domains or multimers.
Immunoglobulins represent the most prevalent biopharmaceutical products in either manufacture or development worldwide. The high commercial demand for and hence value of this particular therapeutic market has led to the emphasis being placed on pharmaceutical companies to maximize the productivity of their respective mAb manufacturing processes whilst controlling the associated costs.
Affinity chromatography is used in most cases, as one of the key steps in the purification of these immunoglobulin molecules, such as monoclonal or polyclonal antibodies. A particularly interesting class of affinity reagents is proteins capable of specific binding to invariable parts of an immunoglobulin molecule, such interaction being independent on the antigen-binding specificity of the antibody. Such reagents can be widely used for affinity chromatography recovery of immunoglobulins from different samples such as but not limited to serum or plasma preparations or cell culture derived feed stocks. An example of such a protein is staphylococcal protein A, containing domains capable of binding to the Fc and Fab portions of IgG immunoglobulins from different species. These domains are commonly denoted as the E-, D-, A-, B- and C-domains.
Staphylococcal protein A (SpA) based reagents have due to their high affinity and selectivity found a widespread use in the field of biotechnology, e.g. in affinity chromatography for capture and purification of antibodies as well as for detection or quantification. At present, SpA-based affinity medium probably is the most widely used affinity medium for isolation of monoclonal antibodies and their fragments from different samples including industrial cell culture supernatants. Accordingly, various matrices comprising protein A-ligands are commercially available, for example, in the form of native protein A (e.g. Protein A SEPHAROSE™, GE Healthcare, Uppsala, Sweden) and also comprised of recombinant protein A (e.g. rProtein A-SEPHAROSE™, GE Healthcare). More specifically, the genetic manipulation performed in the commercial recombinant protein A product is aimed at facilitating the attachment thereof to a support and at increasing the productivity of the ligand.
These applications, like other affinity chromatography applications, require comprehensive attention to definite removal of contaminants. Such contaminants can for example be non-eluted molecules adsorbed to the stationary phase or matrix in a chromatographic procedure, such as non-desired biomolecules or microorganisms, including for example proteins, carbohydrates, lipids, bacteria and viruses. The removal of such contaminants from the matrix is usually performed after a first elution of the desired product in order to regenerate the matrix before subsequent use. Such removal usually involves a procedure known as cleaning-in-place (CIP), wherein agents capable of eluting contaminants from the stationary phase are used. One such class of agents often used is alkaline solutions that are passed over said stationary phase. At present the most extensively used cleaning and sanitizing agent is NaOH, and the concentration thereof can range from 0.1 up to e.g. 1 M, depending on the degree and nature of contamination. This strategy is associated with exposing the matrix to solutions with pH-values above 13. For many affinity chromatography matrices containing proteinaceous affinity ligands such alkaline environment is a very harsh condition and consequently results in decreased capacities owing to instability of the ligand to the high pH involved.
An extensive research has therefore been focused on the development of engineered protein ligands that exhibit an improved capacity to withstand alkaline pH-values. For example, Gülich et al. (Susanne Gülich, Martin Linhult, Per-Åke Nygren, Mathias Uhlén, Sophia Hober, Journal of Biotechnology 80 (2000), 169-178) suggested protein engineering to improve the stability properties of a Streptococcal albumin-binding domain (ABD) in alkaline environments. Gülich et al. created a mutant of ABD, wherein all the four asparagine residues have been replaced by leucine (one residue), aspartate (two residues) and lysine (one residue). Further, Gülich et al. report that their mutant exhibits a target protein binding behavior similar to that of the native protein, and that affinity columns containing the engineered ligand show higher binding capacities after repeated exposure to alkaline conditions than columns prepared using the parental non-engineered ligand. Thus, it is concluded therein that all four asparagine residues can be replaced without any significant effect on structure and function.
Recent work shows that changes can also be made to protein A (SpA) to effect similar properties. US patent application publication US 2005/0143566, which is hereby incorporated by reference in its entirety, discloses that when at least one asparagine residue is mutated to an amino acid other than glutamine or aspartic acid, the mutation confers an increased chemical stability at pH-values of up to about 13-14 compared to the parental SpA, such as the B-domain of SpA, or Protein Z, a synthetic construct derived from the B-domain of SpA (U.S. Pat. No. 5,143,844, incorporated by reference in its entirety). The authors show that when these mutated proteins are used as affinity ligands, the separation media as expected can better withstand cleaning procedures using alkaline agents. Further mutations of protein A domains with the purpose of increasing the alkali stability have also been published in U.S. Pat. No. 8,329,860, JP 2006304633A, U.S. Pat. No. 8,674,073, US 2010/0221844, US 2012/0208234, U.S. Pat. No. 9,051,375, US 2014/0031522, US 2013/0274451 and WO 2014/146350, all of which are hereby incorporated by reference in their entireties. However, the currently available mutants are still sensitive to alkaline pH and the NaOH concentration during cleaning is usually limited to 0.1 M, which means that complete cleaning is difficult to achieve. Higher NaOH concentrations, which would improve the cleaning, lead to unacceptable capacity losses.
There is thus still a need in this field to obtain a separation matrix containing protein ligands having a further improved stability towards alkaline cleaning procedures. There is also a need for such separation matrices with an improved binding capacity to allow for economically efficient purification of therapeutic antibodies.
One aspect of the invention is to provide a polypeptide with improved alkaline stability. This is achieved with an Fc-binding polypeptide comprising a mutant of a parental Fc-binding domain of Staphylococcus Protein A (SpA), as defined by, or having at least 80% such as at least 90%, 95% or 98% identity to, SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO:3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:22, SEQ ID NO 51 or SEQ ID NO 52, wherein at least the asparagine or serine residue at the position corresponding to position 11 in SEQ ID NO:4-7 has been mutated to an amino acid selected from the group consisting of glutamic acid, lysine, tyrosine, threonine, phenylalanine, leucine, isoleucine, tryptophan, methionine, valine, alanine, histidine and arginine. Alternatively, the polypeptide comprises a sequence as defined by, or having at least 80% or at least 90%, 95% or 98% identity to SEQ ID NO 53.
One advantage is that the alkaline stability is improved over the parental polypeptides, with a maintained highly selective binding towards immunoglobulins and other Fc-containing proteins.
A second aspect of the invention is to provide a multimer with improved alkaline stability, comprising a plurality of polypeptides. This is achieved with a multimer of the polypeptide disclosed above.
A third aspect of the invention is to provide a nucleic acid or a vector encoding a polypeptide or multimer with improved alkaline stability. This is achieved with a nucleic acid or vector encoding a polypeptide or multimer as disclosed above.
A fourth aspect of the invention is to provide an expression system capable of expressing a polypeptide or multimer with improved alkaline stability. This is achieved with an expression system comprising a nucleic acid or vector as disclosed above.
A fifth aspect of the invention is to provide a separation matrix capable of selectively binding immunoglobulins and other Fc-containing proteins and exhibiting an improved alkaline stability. This is achieved with a separation matrix comprising at least 11 mg/ml Fc-binding ligands covalently coupled to a porous support, wherein:
One advantage is that a high dynamic binding capacity is provided. A further advantage is that a high degree of alkali stability is achieved.
A sixth aspect of the invention is to provide an efficient and economical method of isolating an immunoglobulin or other Fc-containing protein. This is achieved with a method comprising the steps of:
Further suitable embodiments of the invention are described in the dependent claims. Co-pending applications PCT EP2015/076639, PCT EP2015/076642, GB 1608229.9 and GB 1608232.3 are hereby incorporated by reference in their entireties.
Definitions
The terms “antibody” and “immunoglobulin” are used interchangeably herein, and are understood to include also fragments of antibodies, fusion proteins comprising antibodies or antibody fragments and conjugates comprising antibodies or antibody fragments.
The terms an “Fc-binding polypeptide” and “Fc-binding protein” mean a polypeptide or protein respectively, capable of binding to the crystallisable part (Fc) of an antibody and includes e.g. Protein A and Protein G, or any fragment or fusion protein thereof that has maintained said binding property.
The term “linker” herein means an element linking two polypeptide units, monomers or domains to each other in a multimer.
The term “spacer” herein means an element connecting a polypeptide or a polypeptide multimer to a support.
The term “% identity” with respect to comparisons of amino acid sequences is determined by standard alignment algorithms such as, for example, Basic Local Alignment Tool (BLAST™) described in Altshul et al. (1990) J. Mol. Biol., 215: 403-410.
A web-based software for this is freely available from the website of US National Library of Medicine. Here, the algorithm “blastp (protein-protein BLAST)” is used for alignment of a query sequence with a subject sequence and determining i.a. the % identity.
As used herein, the terms “comprises,” “comprising,” “containing,” “having” and the like can have the meaning ascribed to them in U.S. Patent law and can mean “includes,” “including,” and the like; “consisting essentially of” or “consists essentially” likewise has the meaning ascribed in U.S. Patent law and the term is open-ended, allowing for the presence of more than that which is recited so long as basic or novel characteristics of that which is recited is not changed by the presence of more than that which is recited, but excludes prior art embodiments.
In one aspect the present invention discloses an Fc-binding polypeptide, which comprises, or consists essentially of, a mutant of an Fc-binding domain of Staphylococcus Protein A (SpA), as defined by, or having at least 90%, at least 95% or at least 98% identity to, SEQ ID NO: 1 (E-domain), SEQ ID NO: 2 (D-domain), SEQ ID NO:3 (A-domain), SEQ ID NO:22 (variant A-domain), SEQ ID NO: 4 (B-domain), SEQ ID NO: 5 (C-domain), SEQ ID NO:6 (Protein Z), SEQ ID NO:7 (Zvar), SEQ ID NO 51 (Zvar without the linker region amino acids 1-8 and 56-58) or SEQ ID NO 52 (C-domain without the linker region amino acids 1-8 and 56-58) as illustrated in
*Throughout this description, the amino acid residue position numbering convention of
In alternative language, the invention discloses an Fc-binding polypeptide which comprises a sequence as defined by, or having at least 90%, at least 95% or at least 98% identity to SEQ ID NO 53.
wherein individually of each other:
Specifically, the amino acid residues in SEQ ID NO 53 may individually of each other be:
In certain embodiments, the amino acid residues in SEQ ID NO 53 may be: X1=A, X2=E, X3=H, X4=N, X6=Q, X7=S, X8=D, X9=V, X10=K, X11=A, X12=I, X13=K, X14=L. In some embodiments X2=E, X3=H, X4=N, X5=A, X6=Q, X7=S, X8=D, X12=I, X13=K, X14=L and X15=D and one or more of X1, X9, X10 and X11 is deleted. In further embodiments, X1=A, X2=E, X3=H, X4=N, X5=S,Y,Q,T,N,F,L,W,I,M,V,D,E,H,R or K, X6=Q, X7=S, X8=D, X9=V, X10=K, X11=A, X12=I, X13=K, X14=L and X15=D, or alternatively X1=A, X2=E, X3=H, X4=N, X5=A, X6=Q, X7=S, X8=D, X9=V, X10=K, X11=A, X12=I, X13=K, X14=L and X15=F,Y,W,K or R.
The N11 (X2) mutation (e.g. a N11E or N11K mutation) may be the only mutation or the polypeptide may also comprise further mutations, such as substitutions in at least one of the positions corresponding to positions 3, 6, 9, 10, 15, 18, 23, 28, 29, 32, 33, 36, 37, 40, 42, 43, 44, 47, 50, 51, 55 and 57 in SEQ ID NO:4-7. In one or more of these positions, the original amino acid residue may e.g. be substituted with an amino acid which is not asparagine, proline or cysteine. The original amino acid residue may e.g. be substituted with an alanine, a valine, a threonine, a serine, a lysine, a glutamic acid or an aspartic acid. Further, one or more amino acid residues may be deleted, e.g. from positions 1-6 and/or from positions 56-58.
In some embodiments, the amino acid residue at the position corresponding to position 9 in SEQ ID NO:4-7 (X1) is an amino acid other than glutamine, asparagine, proline or cysteine, such as an alanine or it can be deleted. The combination of the mutations at positions 9 and 11 provides particularly good alkali stability, as shown by the examples. In specific embodiments, in SEQ ID NO: 7 the amino acid residue at position 9 is an alanine and the amino acid residue at position 11 is a lysine or glutamic acid, such as a lysine. Mutations at position 9 are also discussed in copending application PCT/SE2014/050872, which is hereby incorporated by reference in its entirety.
In some embodiments, the amino acid residue at the position corresponding to position 50 in SEQ ID NO:4-7 (X13) is an arginine or a glutamic acid.
In certain embodiments, the amino acid residue at the position corresponding to position 3 in SEQ ID NO:4-7 is an alanine and/or the amino acid residue at the position corresponding to position 6 in SEQ ID NO:4-7 is an aspartic acid. One of the amino acid residues at positions 3 and 6 may be an asparagine and in an alternative embodiment both amino acid residues at positions 3 and 6 may be asparagines.
In some embodiments the amino acid residue at the position corresponding to position 43 in SEQ ID NO:4-7 (X11) is an alanine or a glutamic acid, such as an alanine or it can be deleted. In specific embodiments, the amino acid residues at positions 9 and 11 in SEQ ID NO: 7 are alanine and lysine/glutamic acid respectively, while the amino acid residue at position 43 is alanine or glutamic acid.
In certain embodiments the amino acid residue at the position corresponding to position 28 in SEQ ID NO:4-7 (X5) is an alanine or an asparagine, such as an alanine.
In some embodiments the amino acid residue at the position corresponding to position 40 in SEQ ID NO:4-7 (X9) is selected from the group consisting of asparagine, alanine, glutamic acid and valine, or from the group consisting of glutamic acid and valine or it can be deleted. In specific embodiments, the amino acid residues at positions 9 and 11 in SEQ ID NO: 7 are alanine and glutamic acid respectively, while the amino acid residue at position 40 is valine. Optionally, the amino acid residue at position 43 may then be alanine or glutamic acid.
In certain embodiments, the amino acid residue at the position corresponding to position 42 in SEQ ID NO:4-7 (X10) is an alanine, lysine or arginine or it can be deleted.
In some embodiments the amino acid residue at the position corresponding to position 18 in SEQ ID NO:4-7 (X3) is a lysine or a histidine, such as a lysine.
In certain embodiments the amino acid residue at the position corresponding to position 33 in SEQ ID NO:4-7 (X7) is a lysine or a serine, such as a lysine.
In some embodiments the amino acid residue at the position corresponding to position 37 in SEQ ID NO:4-7 (X8) is a glutamic acid or an aspartic acid, such as a glutamic acid.
In certain embodiments the amino acid residue at the position corresponding to position 51 in SEQ ID NO:4-7 (X14) is a tyrosine or a leucine, such as a tyrosine.
In some embodiments, the amino acid residue at the position corresponding to position 44 in SEQ ID NO:4-7 (X12) is a leucine or an isoleucine. In specific embodiments, the amino acid residues at positions 9 and 11 in SEQ ID NO: 7 are alanine and lysine/glutamic acid respectively, while the amino acid residue at position 44 is isoleucine. Optionally, the amino acid residue at position 43 may then be alanine or glutamic acid.
In some embodiments, the amino acid residues at the positions corresponding to positions 1, 2, 3 and 4 or to positions 3, 4, 5 and 6 in SEQ ID NO: 4-7 have been deleted. In specific variants of these embodiments, the parental polypeptide is the C domain of Protein A (SEQ ID NO: 5). The effects of these deletions on the native C domain are described in U.S. pat. No. 9,018,305 and U.S. pat. No. 8,329,860, which are hereby incorporated by reference in their entireties.
In certain embodiments, the mutation in SEQ ID NO 4-7, such as in SEQ ID NO 7, is selected from the group consisting of: N11K; N11E; N11Y; N11T; N11F; N11L; N11W; N11I; N11M; N11V; N11A; N11H; N11R; N11E, Q32A; N11E, Q32E, Q40E; N11E, Q32E, K50R; Q9A,N11E,N43A; Q9A,N11E,N28A,N43A; Q9A,N11E,Q40V,A42K,N43E,L44I; Q9A,N11E,Q40V,A42K,N43A,L44I; N11K,H18K,S33K,D37E,A42R,N43A,L44I,K50R,L51Y; Q9A,N11E,N28A,Q40V,A42K,N43A,L44I; Q9A,N11K,H18K,S33K,D37E,A42R,N43A,L44I,K50R,L51Y; N11K, H18K, D37E, A42R, N43A, L44I; Q9A, N11K, H18K, D37E, A42R, N43A, L44I; Q9A, N11K, H18K, D37E, A42R, N43A, L44I, K50R; Q9A,N11K,H18K,D37E,A42R; Q9A,N11E,D37E,Q40V,A42K,N43A,L44I and Q9A,N11E,D37E,Q40V,A42R,N43A,L44I. These mutations provide particularly high alkaline stabilities. The mutation in SEQ ID NO 4-7, such as in SEQ ID NO 7, can also be selected from the group consisting of N11K; N11Y; N11F; N11L; N11W; N11I; N11M; N11V; N11A; N11H; N11R; Q9A,N11E,N43A; Q9A,N11E,N28A,N43A; Q9A,N11E,Q40V,A42K,N43E,L44I; Q9A,N11E,Q40V,A42K,N43A,L44I; Q9A,N11E,N28A,Q40V,A42K,N43A,L44I; N11K,H18K,S33K,D37E,A42R,N43A,L44I,K50R,L51Y; Q9A,N11K,H18K,S33K,D37E,A42R,N43A,L44I,K50R,L51Y; N11K, H18K, D37E, A42R, N43A, L44I; Q9A, N11K, H18K, D37E, A42R, N43A, L44I and Q9A, N11K, H18K, D37E, A42R, N43A, L44I, K50R.
In some embodiments, the polypeptide comprises or consists essentially of a sequence defined by or having at least 90%, 95% or 98% identity to an amino acid sequence selected from the group consisting of: SEQ ID NO 8, SEQ ID NO 9, SEQ ID NO 10, SEQ ID NO 11, SEQ ID NO 12, SEQ ID NO 13, SEQ ID NO 14, SEQ ID NO 15, SEQ ID NO 16, SEQ ID NO 23, SEQ ID NO 24, SEQ ID NO 25, SEQ ID NO 26, SEQ ID NO 27, SEQ ID NO 28, SEQ ID NO 29, SEQ ID NO 36, SEQ ID NO 37, SEQ ID NO 38, SEQ ID NO 39, SEQ ID NO 40, SEQ ID NO 41, SEQ ID NO 42, SEQ ID NO 43, SEQ ID NO 44, SEQ ID NO 45, SEQ ID NO 46, SEQ ID NO 47, SEQ ID NO 48, SEQ ID NO 49 and SEQ ID NO 50. It may e.g. comprise or consist essentially of a sequence defined by or having at least 90%, 95% or 98% identity to an amino acid sequence selected from the group consisting of: SEQ ID NO 8, SEQ ID NO 9, SEQ ID NO 10, SEQ ID NO 11, SEQ ID NO 16, SEQ ID NO 23, SEQ ID NO 24, SEQ ID NO 25, SEQ ID NO 26, SEQ ID NO 27, SEQ ID NO 28 and SEQ ID NO 29. It can also comprise or consist essentially of a sequence defined by or having at least 90%, 95% or 98% identity to an amino acid sequence selected from the group consisting of: SEQ ID NO 8, SEQ ID NO 9, SEQ ID NO 10, SEQ ID NO 11, SEQ ID NO 16, SEQ ID NO 23, SEQ ID NO 24, SEQ ID NO 25, SEQ ID NO 27, SEQ ID NO 28, SEQ ID NO 38, SEQ ID NO 40; SEQ ID NO 41; SEQ ID NO 42; SEQ NO 43, SEQ ID NO 44, SEQ ID NO 45, SEQ ID NO 46, SEQ ID NO 47 and SEQ ID NO 48.
In certain embodiments, the polypeptide comprises or consists essentially of a sequence defined by or having at least 90%, 95% or 98% identity to an amino acid sequence selected from the group consisting of SEQ ID NO 54-70. comprises or consists essentially of a sequence defined by or having at least 90%, 95% or 98% identity to an amino acid sequence selected from the group consisting of SEQ ID NO 71-75, or it may comprise or consist essentially of a sequence defined by or having at least 90%, 95% or 98% identity to an amino acid sequence selected from the group consisting of SEQ ID NO 76-79. It may further comprise or consist essentially of a sequence defined by or having at least 90%, 95% or 98% identity to an amino acid sequence selected from the group consisting of SEQ ID NO 89-95.
The polypeptide may e.g. be defined by a sequence selected from the groups above or from subsets of these groups, but it may also comprise additional amino acid residues at the N- and/or C-terminal end, e.g. a leader sequence at the N-terminal end and/or a tail sequence at the C-terminal end.
S
AILAEAKK LNDAQAPK
AKFDKEAQ EAFYEILHLP NLTEEQRNAF IQSLKDDPSV
KFDKEAQ EAFYEILHLP NLTEEQRNAF IQSLKDDPSV
AQ EAFYEILHLP NLTEEQRNAF IQSLKDDPSV
In a second aspect the present invention discloses a multimer comprising, or consisting essentially of, a plurality of polypeptide units as defined by any embodiment disclosed above. The use of multimers may increase the immunoglobulin binding capacity and multimers may also have a higher alkali stability than monomers. The multimer can e.g. be a dimer, a trimer, a tetramer, a pentamer, a hexamer, a heptamer, an octamer or a nonamer. It can be a homomultimer, where all the units in the multimer are identical or it can be a heteromultimer, where at least one unit differs from the others. Advantageously, all the units in the multimer are alkali stable, such as by comprising the mutations disclosed above. The polypeptides can be linked to each other directly by peptide bonds between the C-terminal and N-terminal ends of the polypeptides. Alternatively, two or more units in the multimer can be linked by linkers comprising oligomeric or polymeric species, such as linkers comprising peptides with up to 25 or 30amino acids, such as 3-25 or 3-20 amino acids. The linkers may e.g. comprise or consist essentially of a peptide sequence defined by, or having at least 90% identity or at least 95% identity, with an amino acid sequence selected from the group consisting of APKVDAKFDKE (SEQ ID NO: 96), APKVDNKFNKE (SEQ ID NO: 97), APKADNKFNKE (SEQ ID NO: 98), APKVFDKE (SEQ ID NO: 99), APAKFDKE (SEQ ID NO: 100), AKFDKE (SEQ ID NO: 101), APKVDA (SEQ ID NO: 102), VDAKFDKE (SEQ ID NO: 103), APKKFDKE (SEQ ID NO: 104), APK, APKYEDGVDAKFDKE (SEQ ID NO: 105) and YEDG (SEQ ID NO: 106) or alternatively selected from the group consisting of APKADNKFNKE (SEQ ID NO: 98), APKVFDKE (SEQ ID NO: 99), APAKFDKE (SEQ ID NO: 100), AKFDKE (SEQ ID NO: 101), APKVDA (SEQ ID NO: 102), VDAKFDKE (SEQ ID NO: 103), APKKFDKE (SEQ ID NO: 104), APKYEDGVDAKFDKE (SEQ ID NO: 105) and YEDG (SEQ ID NO: 106). They can also consist essentially of a peptide sequence defined by or having at least 90% identity or at least 95% identity with an amino acid sequence selected from the group consisting of APKADNKFNKE (SEQ ID NO: 98), APKVFDKE (SEQ ID NO: 99), APAKFDKE (SEQ ID NO: 100), AKFDKE (SEQ ID NO: 101), APKVDA (SEQ ID NO: 102), VDAKFDKE (SEQ ID NO: 103), APKKFDKE (SEQ ID NO: 104), APK and APKYEDGVDAKFDKE (SEQ ID NO: 105). In some embodiments the linkers do not consist of the peptides APKVDAKFDKE (SEQ ID NO: 96) or APKVDNKFNKE (SEQ ID NO: 97), or alternatively do not consist of the peptides APKVDAKFDKE (SEQ ID NO: 96), APKVDNKFNKE (SEQ ID NO: 97), APKFNKE (SEQ ID NO: 107),
APKFDKE (SEQ ID NO: 108), APKVDKE (SEQ ID NO: 109), or APKADKE (SEQ ID
NO: 110).
The nature of such a linker should preferably not destabilize the spatial conformation of the protein units. This can e.g. be achieved by avoiding the presence of proline in the linkers. Furthermore, said linker should preferably also be sufficiently stable in alkaline environments not to impair the properties of the mutated protein units. For this purpose, it is advantageous if the linkers do not contain asparagine. It can additionally be advantageous if the linkers do not contain glutamine The multimer may further at the N-terminal end comprise a plurality of amino acid residues e.g. originating from the cloning process or constituting a residue from a cleaved off signaling sequence. The number of additional amino acid residues may e.g. be 20 or less, such as 15 or less, such as 10 or less or 5 or less. As a specific example, the multimer may comprise an AQ, AQGT (SEQ ID NO: 111), VDAKFDKE (SEQ ID NO: 103), AQVDAKFDKE (SEQ ID NO: 112), or AQGTVDAKFDKE (SEQ ID NO: 113) sequence at the N-terminal end.
In certain embodiments, the multimer may comprise, or consist essentially, of a sequence selected from the group consisting of: SEQ ID NO 80-87. These and additional sequences are listed below and named as Parent(Mutations)n, where n is the number of monomer units in a multimer.
In some embodiments, the polypeptide and/or multimer, as disclosed above, further comprises at the C-terminal or N-terminal end one or more coupling elements, selected from the group consisting of one or more cysteine residues, a plurality of lysine residues and a plurality of histidine residues. The coupling element(s) may also be located within 1-5 amino acid residues, such as within 1-3 or 1-2 amino acid residues from the C-terminal or N-terminal end. The coupling element may e.g. be a single cysteine at the C-terminal end. The coupling element(s) may be directly linked to the C- or N-terminal end, or it/they may be linked via a stretch comprising up to 15 amino acids, such as 1-5, 1-10 or 5-10 amino acids. This stretch should preferably also be sufficiently stable in alkaline environments not to impair the properties of the mutated protein. For this purpose, it is advantageous if the stretch does not contain asparagine. It can additionally be advantageous if the stretch does not contain glutamine. An advantage of having a C-terminal cysteine is that endpoint coupling of the protein can be achieved through reaction of the cysteine thiol with an electrophilic group on a support. This provides excellent mobility of the coupled protein which is important for the binding capacity.
The alkali stability of the polypeptide or multimer can be assessed by coupling it to an SPR chip, e.g. to Biacore CM5 sensor chips as described in the examples, using e.g. NHS- or maleimide coupling chemistries, and measuring the immunoglobulin-binding capacity of the chip, typically using polyclonal human IgG, before and after incubation in alkaline solutions at a specified temperature, e.g. 22+/−2° C. The incubation can e.g. be performed in 0.5 M NaOH for a number of 10 min cycles, such as 100, 200 or 300 cycles. The IgG capacity of the matrix after 100 10 min incubation cycles in 0.5 M NaOH at 22+/−2° C. can be at least 55, such as at least 60, at least 80 or at least 90% of the IgG capacity before the incubation. Alternatively, the remaining IgG capacity after 100 cycles for a particular mutant measured as above can be compared with the remaining IgG capacity for the parental polypeptide/multimer. In this case, the remaining IgG capacity for the mutant may be at least 105%, such as at least 110%, at least 125%, at least 150% or at least 200% of the parental polypeptide/multimer.
In a third aspect the present invention discloses a nucleic acid encoding a polypeptide or multimer according to any embodiment disclosed above. Thus, the invention encompasses all forms of the present nucleic acid sequence such as the RNA and the DNA encoding the polypeptide or multimer. The invention embraces a vector, such as a plasmid, which in addition to the coding sequence comprises the required signal sequences for expression of the polypeptide or multimer according the invention. In one embodiment, the vector comprises nucleic acid encoding a multimer according to the invention, wherein the separate nucleic acids encoding each unit may have homologous or heterologous DNA sequences.
In a fourth aspect the present invention discloses an expression system, which comprises, a nucleic acid or a vector as disclosed above. The expression system may e.g. be a gram-positive or gram-negative prokaryotic host cell system, e.g. E.coli or Bacillus sp. which has been modified to express the present polypeptide or multimer. In an alternative embodiment, the expression system is a eukaryotic host cell system, such as a yeast, e.g. Pichia pastoris or Saccharomyces cerevisiae, or mammalian cells, e.g. CHO cells.
In a fifth aspect, the present invention discloses a separation matrix, wherein a plurality of polypeptides or multimers according to any embodiment disclosed above have been coupled to a solid support. The separation matrix may comprise at least 11, such as 11-21, 15-21 or 15-18 mg/ml Fc-binding ligands covalently coupled to a porous support, wherein:
In certain embodiments the alkali-stabilized Protein A domains comprise mutants of a parental Fc-binding domain of Staphylococcus Protein A (SpA), as defined by, or having at least 80% such as at least 90%, 95% or 98% identity to, SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO:3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:22, SEQ ID NO 51 or SEQ ID NO 52, wherein at least the asparagine or serine residue at the position corresponding to position 11 in SEQ ID NO:4-7 has been mutated to an amino acid selected from the group consisting of glutamic acid, lysine, tyrosine, threonine, phenylalanine, leucine, isoleucine, tryptophan, methionine, valine, alanine, histidine and arginine, such as an amino acid selected from the group consisting of glutamic acid and lysine. The amino acid residue at the position corresponding to position 40 in SEQ ID NO:4-7 may further be, or be mutated to, a valine. The alkali-stabilized Protein A domains may also comprise any mutations as described in the polypeptide and/or multimer embodiments above.
In some embodiments the alkali-stabilized Protein A domains comprise an Fc-binding polypeptide having an amino acid sequence as defined by, or having at least 80% or at least 90, 95% or 98% identity to SEQ ID NO 53.
wherein individually of each other:
In some embodiments, the amino acid residues may individually of each other be:
In certain embodiments the invention discloses a separation matrix comprising at least 15, such as 15-21 or 15-18 mg/ml Fc-binding ligands covalently coupled to a porous support, wherein the ligands comprise multimers of alkali-stabilized Protein A domains. These multimers can suitably be as disclosed in any of the embodiments described above or as specified below.
Such a matrix is useful for separation of immunoglobulins or other Fc-containing proteins and, due to the improved alkali stability of the polypeptides/multimers, the matrix will withstand highly alkaline conditions during cleaning, which is essential for long-term repeated use in a bioprocess separation setting. The alkali stability of the matrix can be assessed by measuring the immunoglobulin-binding capacity, typically using polyclonal human IgG, before and after incubation in alkaline solutions at a specified temperature, e.g. 22+/−2° C. The incubation can e.g. be performed in 0.5 M or 1.0 M NaOH for a number of 15 min cycles, such as 100, 200 or 300 cycles, corresponding to a total incubation time of 25, 50 or 75 h. The IgG capacity of the matrix after 96-100 15 min incubation cycles or a total incubation time of 24 or 25 h in 0.5 M NaOH at 22+/−2° C. can be at least 80, such as at least 85, at least 90 or at least 95% of the IgG capacity before the incubation. The capacity of the matrix after a total incubation time of 24 h in 1.0 M NaOH at 22+/−2° C. can be at least 70, such as at least 80 or at least 90% of the IgG capacity before the incubation. The the 10% breakthrough dynamic binding capacity (Qb10%) for IgG at 2.4 min or 6 min residence time may e.g. be reduced by less than 20% after incubation 31 h in 1.0 M aqueous NaOH at 22+/−2 C.
As the skilled person will understand, the expressed polypeptide or multimer should be purified to an appropriate extent before being immobilized to a support. Such purification methods are well known in the field, and the immobilization of protein-based ligands to supports is easily carried out using standard methods. Suitable methods and supports will be discussed below in more detail.
The solid support of the matrix according to the invention can be of any suitable well-known kind. A conventional affinity separation matrix is often of organic nature and based on polymers that expose a hydrophilic surface to the aqueous media used, i.e. expose hydroxy (—OH), carboxy (—COOH), carboxamido (—CONH2, possibly in N— substituted forms), amino (—NH2, possibly in substituted form), oligo- or polyethylenoxy groups on their external and, if present, also on internal surfaces. The solid support can suitably be porous. The porosity can be expressed as a Kav or Kd value (the fraction of the pore volume available to a probe molecule of a particular size) measured by inverse size exclusion chromatography, e.g. according to the methods described in Gel Filtration Principles and Methods, Pharmacia LKB Biotechnology 1991, pp 6-13. Kav is determined as the ratio (Ve−V0)/(Vt−V0), where Ve is the elution volume of a probe molecule (e.g. Dextran 110 kD), V0 is the void volume of the column (e.g. the elution volume of a high Mw void marker, such as raw dextran) and Vt is the total volume of the column. Kd can be determined as (Ve−V0)/Vi, where Vi is the elution volume of a salt (e.g. NaCl) able to access all the volume except the matrix volume (the volume occupied by the matrix polymer molecules). By definition, both Kd and Kav values always lie within the range 0-1. The Kav value can advantageously be 0.6-0.95, e.g. 0.7-0.90 or 0.6-0.8, as measured with dextran of Mw 110 kDa as a probe molecule. The Kd value as measured with dextran of Mw 110 kDa can suitably be 0.68-0.90, such as 0.68-0.85 or 0.70-0.85. An advantage of this is that the support has a large fraction of pores able to accommodate both the polypeptides/multimers of the invention and immunoglobulins binding to the polypeptides/multimers and to provide mass transport of the immunoglobulins to and from the binding sites.
The polypeptides or multimers may be attached to the support via conventional coupling techniques utilising e.g. thiol, amino and/or carboxy groups present in the ligand. Bisepoxides, epichlorohydrin, CNBr, N-hydroxysuccinimide (NHS) etc are well-known coupling reagents. Between the support and the polypeptide/multimer, a molecule known as a spacer can be introduced, which improves the availability of the polypeptide/multimer and facilitates the chemical coupling of the polypeptide/multimer to the support. Depending on the nature of the polypeptide/multimer and the coupling conditions, the coupling may be a multipoint coupling (e.g. via a plurality of lysines) or a single point coupling (e.g. via a single cysteine). Alternatively, the polypeptide/multimer may be attached to the support by non-covalent bonding, such as physical adsorption or biospecific adsorption.
In some embodiments the matrix comprises 5-25, such as 5-20 mg/ml, 5-15 mg/ml, 5-11 mg/ml or 6-11 mg/ml of the polypeptide or multimer coupled to the support. The amount of coupled polypeptide/multimer can be controlled by the concentration of polypeptide/multimer used in the coupling process, by the activation and coupling conditions used and/or by the pore structure of the support used. As a general rule the absolute binding capacity of the matrix increases with the amount of coupled polypeptide/multimer, at least up to a point where the pores become significantly constricted by the coupled polypeptide/multimer. Without being bound by theory, it appears though that for the Kd values recited for the support, the constriction of the pores by coupled ligand is of lower significance. The relative binding capacity per mg coupled polypeptide/multimer will decrease at high coupling levels, resulting in a cost-benefit optimum within the ranges specified above.
In certain embodiments the polypeptides or multimers are coupled to the support via thioether bonds. Methods for performing such coupling are well-known in this field and easily performed by the skilled person in this field using standard techniques and equipment. Thioether bonds are flexible and stable and generally suited for use in affinity chromatography. In particular when the thioether bond is via a terminal or near-terminal cysteine residue on the polypeptide or multimer, the mobility of the coupled polypeptide/multimer is enhanced which provides improved binding capacity and binding kinetics. In some embodiments the polypeptide/multimer is coupled via a C-terminal cysteine provided on the protein as described above. This allows for efficient coupling of the cysteine thiol to electrophilic groups, e.g. epoxide groups, halohydrin groups etc. on a support, resulting in a thioether bridge coupling.
In certain embodiments the support comprises a polyhydroxy polymer, such as a polysaccharide. Examples of polysaccharides include e.g. dextran, starch, cellulose, pullulan, agar, agarose etc. Polysaccharides are inherently hydrophilic with low degrees of nonspecific interactions, they provide a high content of reactive (activatable) hydroxyl groups and they are generally stable towards alkaline cleaning solutions used in bioprocessing.
In some embodiments the support comprises agar or agarose. The supports used in the present invention can easily be prepared according to standard methods, such as inverse suspension gelation (S Hjertén: Biochim Biophys Acta 79(2), 393-398 (1964). Alternatively, the base matrices are commercially available products, such as crosslinked agarose beads sold under the name of SEPHAROSE™ FF (GE Healthcare). In an embodiment, which is especially advantageous for large-scale separations, the support has been adapted to increase its rigidity using the methods described in U.S. Pat. No. 6,602,990 or U.S. Pat. No. 7,396,467, which are hereby incorporated by reference in their entireties, and hence renders the matrix more suitable for high flow rates.
In certain embodiments the support, such as a polymer, polysaccharide or agarose support, is crosslinked, such as with hydroxyalkyl ether crosslinks. Crosslinker reagents producing such crosslinks can be e.g. epihalohydrins like epichlorohydrin, diepoxides like butanediol diglycidyl ether, allylating reagents like allyl halides or allyl glycidyl ether. Crosslinking is beneficial for the rigidity of the support and improves the chemical stability. Hydroxyalkyl ether crosslinks are alkali stable and do not cause significant nonspecific adsorption.
Alternatively, the solid support is based on synthetic polymers, such as polyvinyl alcohol, polyhydroxyalkyl acrylates, polyhydroxyalkyl methacrylates, polyacrylamides, polymethacrylamides etc. In case of hydrophobic polymers, such as matrices based on divinyl and monovinyl-substituted benzenes, the surface of the matrix is often hydrophilised to expose hydrophilic groups as defined above to a surrounding aqueous liquid. Such polymers are easily produced according to standard methods, see e.g. “Styrene based polymer supports developed by suspension polymerization” (R Arshady: Chimica e L'Industria 70(9), 70-75 (1988)). Alternatively, a commercially available product, such as SOURCE™ (GE Healthcare) is used. In another alternative, the solid support according to the invention comprises a support of inorganic nature, e.g. silica, zirconium oxide etc.
In yet another embodiment, the solid support is in another form such as a surface, a chip, capillaries, or a filter (e.g. a membrane or a depth filter matrix).
As regards the shape of the matrix according to the invention, in one embodiment the matrix is in the form of a porous monolith. In an alternative embodiment, the matrix is in beaded or particle form that can be porous or non-porous. Matrices in beaded or particle form can be used as a packed bed or in a suspended form. Suspended forms include those known as expanded beds and pure suspensions, in which the particles or beads are free to move. In case of monoliths, packed bed and expanded beds, the separation procedure commonly follows conventional chromatography with a concentration gradient. In case of pure suspension, batch-wise mode will be used.
In a sixth aspect, the present invention discloses a method of isolating an immunoglobulin, wherein a separation matrix as disclosed above is used. The method may comprise the steps of:
In certain embodiments, the method comprises the steps of:
The elution may be performed by using any suitable solution used for elution from Protein A media. This can e.g. be a solution or buffer with pH 5 or lower, such as pH 2.5-5 or 3-5. It can also in some cases be a solution or buffer with pH 11 or higher, such as pH 11-14 or pH 11-13. In some embodiments the elution buffer or the elution buffer gradient comprises at least one mono- di- or trifunctional carboxylic acid or salt of such a carboxylic acid. In certain embodiments the elution buffer or the elution buffer gradient comprises at least one anion species selected from the group consisting of acetate, citrate, glycine, succinate, phosphate, and formiate.
In some embodiments, the cleaning liquid is alkaline, such as with a pH of 13-14. Such solutions provide efficient cleaning of the matrix, in particular at the upper end of the interval
In certain embodiments, the cleaning liquid comprises 0.1-2.0 M NaOH or KOH, such as 0.5-2.0 or 0.5-1.0 M NaOH or KOH. These are efficient cleaning solutions, and in particular so when the NaOH or KOH concentration is above 0.1 M or at least 0.5 M. The high stability of the polypeptides of the invention enables the use of such strongly alkaline solutions.
The method may also include a step of sanitizing the matrix with a sanitization liquid, which may e.g. comprise a peroxide, such as hydrogen peroxide and/or a peracid, such as peracetic acid or performic acid.
In some embodiments, steps a)-d) are repeated at least 10 times, such as at least 50 times, 50-200, 50-300 or 50-500 times. This is important for the process economy in that the matrix can be re-used many times.
Steps a)-c) can also be repeated at least 10 times, such as at least 50 times, 50-200, 50-300 or 50-500 times, with step d) being performed after a plurality of instances of step c), such that step d) is performed at least 10 times, such as at least 50 times. Step d) can e.g. be performed every second to twentieth instance of step c).
Mutagenesis of Protein
Site-directed mutagenesis was performed by a two-step PCR using oligonucleotides coding for the mutations. As template a plasmid containing a single domain of either Z, B or C was used. The PCR fragments were ligated into an E. coli expression vector. DNA sequencing was used to verify the correct sequence of inserted fragments. To form multimers of mutants an Acc I site located in the starting codons (GTA GAC) of the B, C or Z domain was used, corresponding to amino acids VD. The vector for the monomeric domain was digested with Acc I and phosphatase treated. Acc I sticky-ends primers were designed, specific for each variant, and two overlapping PCR products were generated from each template. The PCR products were purified and the concentration was estimated by comparing the PCR products on a 2% agarose gel. Equal amounts of the pair wise PCR products were hybridized (90° C.->25° C. in 45 min) in ligation buffer. The resulting product consists approximately to ¼ of fragments likely to be ligated into an Acc I site (correct PCR fragments and/or the digested vector). After ligation and transformation colonies were PCR screened to identify constructs containing the desired mutant. Positive clones were verified by DNA sequencing.
Construct Expression and Purification
The constructs were expressed in the bacterial periplasm by fermentation of E. coli K12 in standard media. After fermentation the cells were heat-treated to release the periplasm content into the media. The constructs released into the medium were recovered by microfiltration with a membrane having a 0.2 μm pore size.
Each construct, now in the permeate from the filtration step, was purified by affinity. The permeate was loaded onto a chromatography medium containing immobilized IgG (IgG Sepharose 6FF, GE Healthcare). The loaded product was washed with phosphate buffered saline and eluted by lowering the pH.
The elution pool was adjusted to a neutral pH (pH 8) and reduced by addition of dithiothreitol. The sample was then loaded onto an anion exchanger. After a wash step the construct was eluted in a NaCl gradient to separate it from any contaminants. The elution pool was concentrated by ultrafiltration to 40-50 mg/ml. It should be noted that the successful affinity purification of a construct on an immobilized IgG medium indicates that the construct in question has a high affinity to IgG.
The purified ligands were analyzed with RPC LC-MS to determine the purity and to ascertain that the molecular weight corresponded to the expected (based on the amino acid sequence).
The purified monomeric ligands listed in Table 1, further comprising for SEQ ID NO 8-16, 23-28 and 36-48 an AQGT leader sequence at the N-terminus and a cysteine at the C terminus, were immobilized on Biacore CM5 sensor chips (GE Healthcare, Sweden), using the amine coupling kit of GE Healthcare (for carbodiimide coupling of amines on the carboxymethyl groups on the chip) in an amount sufficient to give a signal strength of about 200-1500 RU in a Biacore surface plasmon resonance (SPR) instrument (GE Healthcare, Sweden). To follow the IgG binding capacity of the immobilized surface lmg/ml human polyclonal IgG (Gammanorm) was flowed over the chip and the signal strength (proportional to the amount of binding) was noted. The surface was then cleaned-in-place (CIP), i.e. flushed with 500 mM NaOH for 10 minutes at room temperature (22+/−2° C.). This was repeated for 96-100 cycles and the immobilized ligand alkaline stability was followed as the remaining IgG binding capacity (signal strength) after each cycle. The results are shown in Table 1 and indicate that at least the ligands Zvar(N11K)1, Zvar(N11E)1, Zvar(N11Y)1, Zvar(N11T)1, Zvar(N11F)1, Zvar(N11L)1, Zvar(N11W)1, ZN11I)1, Zvar(N11M)1, Zvar(N11V)1, Zvar(N11A)1, Zvar(N11H1), Zvar(N11R)1, Zvar(N11E,Q32A)1, Zvar(N11E,Q32E, Q40E)1 and Zvar(N11E,Q32E,K50R)1, Zvar(Q9A,N11E,N43A)1, Zvar(Q9A,N11E,N28A,N43A)1, Zvar(Q9A,N11E,Q40V,A42K,N43E,L44I)1, Zvar(Q9A,N11E,Q40V,A42K,N43A,L44I)1, Zvar(Q9A,N11E,N28A,Q40V,A42K,N43A,L44I)1, Zvar(N11K,H18K,S33K,D37E,A42R,N43A,L44I,K50R,L51Y)1, Zvar(Q9A,N11K,H18K,S33K,D37E,A42R,N43A,L44I,K50R,L51Y)1, Zvar(N11K, H18K, D37E, A42R, N43A, L44I)1, Zvar(Q9A, N11K, H18K, D37E, A42R, N43A, L44I)1 and Zvar(Q9A, N11K, H18K, D37E, A42R, N43A, L44I, K50R)1, as well as the varieties of Zvar(Q9A,N11E,Q40V,A42K,N43A,L44I having G,S,Y,Q,T,N,F,L,W,I,M,V,D,E,H,R or K in position 29, the varieties of Zvar(Q9A,N11E,Q40V,A42K,N43A,L44I)1 having F,Y,W,K or R in position 53 and the varieties of Zvar(Q9A,N11E,Q40V,A42K,N43A,L44I)1 where Q9, Q40, A42 or N43 has been deleted, have an improved alkali stability compared to the parental structure Zvar1, used as the reference. Further, the ligands B(Q9A,N11E,Q40V,A42K,N43A,L44I)1 and C(Q9A,N11E,E43A)1 have an improved stability compared to the parental B and C domains, used as references.
The Biacore experiment can also be used to determine the binding and dissociation rates between the ligand and IgG. This was used with the set-up as described above and with an IgG1 monoclonal antibody as probe molecule. For the reference Zvar1, the on-rate (105 M−1s−1) was 3.1 and the off-rate (105 s−1) was 22.1, giving an affinity (off-rate/on-rate) of 713 pM. For Zvar(Q9A,N11E,Q40V,A42K,N43A,L44I)1 (SEQ ID NO. 11), the on-rate was 4.1 and the off-rate 43.7, with affinity 1070 pM. The IgG affinity was thus somewhat higher for the mutated variant.
The purified dimeric, tetrameric and hexameric ligands listed in Table 2 were immobilized on Biacore CM5 sensor chips (GE Healthcare, Sweden), using the amine coupling kit of GE Healthcare (for carbodiimide coupling of amines on the carboxymethyl groups on the chip) in an amount sufficient to give a signal strength of about 200-1500 RU in a Biacore instrument (GE Healthcare, Sweden) . To follow the IgG binding capacity of the immobilized surface 1 mg/ml human polyclonal IgG (Gammanorm) was flowed over the chip and the signal strength (proportional to the amount of binding) was noted. The surface was then cleaned-in-place (CIP), i.e. flushed with 500 mM NaOH for 10 minutes at room temperature (22+/−2° C.). This was repeated for 300 cycles and the immobilized ligand alkaline stability was followed as the remaining IgG binding capacity (signal strength) after each cycle. The results are shown in Table 2 and in
Example 2 was repeated with 100 CIP cycles of three ligands using 1 M NaOH instead of 500 mM as in Example 2. The results are shown in Table 3 and show that all three ligands have an improved alkali stability also in 1M NaOH, compared to the parental structure Zvar4 which was used as a reference.
The purified tetrameric ligands of Table 2 (all with an additional N-terminal cysteine) were immobilized on agarose beads using the methods described below and assessed for capacity and stability. The results are shown in Table 4 and
Activation
The base matrix used was rigid cross-linked agarose beads of 85 micrometers (volume-weighted, d50V) median diameter, prepared according to the methods of U.S. Pat. No. 6,602,990, hereby incorporated by reference in its entirety, and with a pore size corresponding to an inverse gel filtration chromatography Kav value of 0.70 for dextran of Mw 110 kDa, according to the methods described in Gel Filtration Principles and Methods, Pharmacia LKB Biotechnology 1991, pp 6-13.
25 mL (g) of drained base matrix, 10.0 mL distilled water and 2.02 g NaOH (s) was mixed in a 100 mL flask with mechanical stirring for 10 min at 25° C. 4.0 mL of epichlorohydrin was added and the reaction progressed for 2 hours. The activated gel was washed with 10 gel sediment volumes (GV) of water.
Coupling
To 20 mL of ligand solution (50 mg/mL) in a 50 ml Falcon tube, 169 mg NaHCO3, 21 mg Na2CO3, 175 mg NaCl and 7 mg EDTA, was added. The Falcon tube was placed on a roller table for 5-10 min, and then 77 mg of DTE was added. Reduction proceeded for >45 min The ligand solution was then desalted on a PD10 column packed with Sephadex G-25. The ligand content in the desalted solution was determined by measuring the 276 nm UV absorption.
The activated gel was washed with 3-5 GV {0.1 M phosphate/1 mM EDTA pH 8.6} and the ligand was then coupled according to the method described in U.S. Pat. No. 6,399,750, hereby incorporated by reference in its entirety. All buffers used in the experiments had been degassed by nitrogen gas for at least 5-10 min The ligand content of the gels could be controlled by varying the amount and concentration of the ligand solution.
After immobilization the gels were washed 3×GV with distilled water. The gels +1 GV {0.1 M phosphate/1 mM EDTA/10% thioglycerol pH 8.6} was mixed and the tubes were left in a shaking table at room temperature overnight. The gels were then washed alternately with 3×GV {0.1 M TRIS/0.15 M NaCl pH 8.6} and 0.5 M HAc and then 8-10×GV with distilled water. Gel samples were sent to an external laboratory for amino acid analysis and the ligand content (mg/ml gel) was calculated from the total amino acid content.
Protein
Gammanorm 165 mg/ml (Octapharma), diluted to 2 mg/ml in Equilibration buffer.
Equilibration Buffer
PBS Phosphate buffer 10 mM+0.14 M NaCl+0.0027 M KCl, pH 7.4 (Medicago)
Adsorption Buffer
PBS Phosphate buffer 10 mM+0.14 M NaCl+0.0027 M KCl, pH 7.4 (Medicago)
Elution Buffers
100 mM acetate pH 2.9
Dynamic Binding Capacity
2 ml of resin was packed in TRICORN™ 5 100 columns. The breakthrough capacity was determined with an ÄKTAExplorer 10 system at a residence time of 6 minutes (0.33 ml/min flow rate). Equilibration buffer was run through the bypass column until a stable baseline was obtained. This was done prior to auto zeroing. Sample was applied to the column until a 100% UV signal was obtained. Then, equilibration buffer was applied again until a stable baseline was obtained.
Sample was loaded onto the column until a UV signal of 85% of maximum absorbance was reached. The column was then washed with 5 column volumes (CV) equilibration buffer at flow rate 0.5 ml/min. The protein was eluted with 5 CV elution buffer at a flow rate of 0.5 ml/min. Then the column was cleaned with 0.5M NaOH at flow rate 0.2 ml/min and re-equilibrated with equilibration buffer.
For calculation of breakthrough capacity at 10%, the equation below was used. That is the amount of IgG that is loaded onto the column until the concentration of IgG in the column effluent is 10% of the IgG concentration in the feed.
The dynamic binding capacity (DBC) at 10% breakthrough was calculated. The dynamic binding capacity (DBC) was calculated for 10 and 80% breakthrough.
CIP—0.5 M NaOH
The 10% breakthrough DBC (Qb10) was determined both before and after repeated exposures to alkaline cleaning solutions. Each cycle included a CIP step with 0.5 M NaOH pumped through the column at a rate of 0.5/min for 20 min, after which the column was left standing for 4 h. The exposure took place at room temperature (22+/−2° C.). After this incubation, the column was washed with equilibration buffer for 20 min at a flow rate of 0.5 ml/min Table 4 shows the remaining capacity after six 4 h cycles (i.e. 24 h cumulative exposure time to 0.5 M NaOH), both in absolute numbers and relative to the initial capacity.
Example 4 was repeated with the tetrameric ligands shown in Table 5, but with 1.0 M NaOH used in the CIP steps instead of 0.5 M. The results are shown in Table 5 and in
Base Matrices
The base matrices used were a set of rigid cross-linked agarose bead samples of 59-93 micrometers (volume-weighted, d50V) median diameter (determined on a Malvern Mastersizer 2000 laser diffraction instrument), prepared according to the methods of U.S. Pat. No. 6,602,990 and with a pore size corresponding to an inverse gel filtration chromatography Kd value of 0.62-0.82 for dextran of Mw 110 kDa, according to the methods described above, using HR10/30 columns (GE Healthcare) packed with the prototypes in 0.2 M NaCl and with a range of dextran fractions as probe molecules (flow rate 0.2 ml/min). The dry weight of the bead samples ranged from 53 to 86 mg/ml, as determined by drying 1.0 ml drained filter cake samples at 105° C. over night and weighing.
Coupling
100 ml base matrix was washed with 10 gel volumes distilled water on a glass filter. The gel was weighed (1 g=1 ml) and mixed with 30 ml distilled water and 8.08 g NaOH (0.202 mol) in a 250 ml flask with an agitator. The temperature was adjusted to 27+/−2° C. in a water bath. 16 ml epichlorohydrin (0.202 mol) was added under vigorous agitation (about 250 rpm) during 90+/−10 minutes. The reaction was allowed to continue for another 80+/−10 minutes and the gel was then washed with >10 gel volumes distilled water on a glass filter until neutral pH was reached. This activated gel was used directly for coupling as below.
To 16.4 mL of ligand solution (50 mg/mL) in a 50 ml Falcon tube, 139 mg NaHCO3, 17.4 mg Na2CO3, 143.8 mg NaCl and 141 mg EDTA, was added. The Falcon tube was placed on a roller table for 5-10 min, and then 63 mg of DTE was added. Reduction proceeded for >45 min. The ligand solution was then desalted on a PD10 column packed with Sephadex G-25. The ligand content in the desalted solution was determined by measuring the 276 nm UV absorption.
The activated gel was washed with 3-5 GV {0.1 M phosphate/1 mM EDTA pH 8.6} and the ligand was then coupled according to the method described in U.S. Pat. No. 6,399,750 5.2.2, although with considerably higher ligand amounts (see below). All buffers used in the experiments had been degassed by nitrogen gas for at least 5-10 min The ligand content of the gels was controlled by varying the amount and concentration of the ligand solution, adding 5-20 mg ligand per ml gel. The ligand was either a tetramer (SEQ ID NO. 20) or a hexamer (SEQ ID NO. 33) of an alkali-stabilized mutant.
After immobilization the gels were washed 3×GV with distilled water. The gels+1 GV {0.1 M phosphate/1 mM EDTA/10% thioglycerol pH 8.6} was mixed and the tubes were left in a shaking table at room temperature overnight. The gels were then washed alternately with 3×GV {0.1 M TRIS/0.15 M NaCl pH 8.6} and 0.5 M HAc and then 8-10×GV with distilled water. Gel samples were sent to an external laboratory for amino acid analysis and the ligand content (mg/ml gel) was calculated from the total amino acid content.
Evaluation
The Qb10% dynamic capacity for polyclonal human IgG at 2.4 and 6 min residence time was determined as outlined in Example 4.
A series of prototypes, prepared as above, with different ligand content (tetramer, SEQ ID NO:20) were incubated in 1 M NaOH for 4, 8 and 31 hours at 22+/−2° C. and the dynamic IgG capacity (Qb10%, 6 min residence time) was measured before and after incubation. The prototypes are shown in Table 8 and the results in
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. All patents and patent applications mentioned in the text are hereby incorporated by reference in their entireties, as if they were individually incorporated.
i. An Fc-binding polypeptide which comprises a sequence as defined by, or having at least 90% or at least 95% or 98% identity to SEQ ID NO 53.
wherein individually of each other:
wherein individually of each other:
| Number | Date | Country | Kind |
|---|---|---|---|
| 1608232.3 | May 2016 | GB | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4704366 | Juarez-Salinas et al. | Nov 1987 | A |
| 4708714 | Larsson et al. | Nov 1987 | A |
| 4801687 | Ngo | Oct 1989 | A |
| 4933435 | Ngo | Jun 1990 | A |
| 5011686 | Pang | Apr 1991 | A |
| 5084398 | Huston et al. | Jan 1992 | A |
| 5143844 | Abrahmsen et al. | Sep 1992 | A |
| 5476786 | Huston | Dec 1995 | A |
| 5831012 | Nilsson et al. | Nov 1998 | A |
| 6127526 | Blank | Oct 2000 | A |
| 6207804 | Huston et al. | Mar 2001 | B1 |
| 6399750 | Johansson | Jun 2002 | B1 |
| 6602990 | Berg | Aug 2003 | B1 |
| 6870034 | Breece et al. | Mar 2005 | B2 |
| 7220356 | Thommes et al. | May 2007 | B2 |
| 7396467 | Berg et al. | Jul 2008 | B2 |
| 7566565 | Peters et al. | Jul 2009 | B2 |
| 7709209 | Hober et al. | May 2010 | B2 |
| 7714111 | Sun et al. | May 2010 | B2 |
| 7820799 | Godavarti et al. | Oct 2010 | B2 |
| 7834158 | Hober | Nov 2010 | B2 |
| 7834162 | Zhou | Nov 2010 | B2 |
| 7884264 | Dickey et al. | Feb 2011 | B2 |
| 7901581 | Bryntesson et al. | Mar 2011 | B2 |
| 8080246 | Lin et al. | Dec 2011 | B2 |
| 8084032 | Yumioka et al. | Dec 2011 | B2 |
| 8182696 | Theoleyre et al. | May 2012 | B2 |
| 8183207 | Lin et al. | May 2012 | B2 |
| 8198404 | Hober | Jun 2012 | B2 |
| 8263750 | Shukla et al. | Sep 2012 | B2 |
| 8282914 | Chou et al. | Oct 2012 | B2 |
| 8329860 | Hall et al. | Dec 2012 | B2 |
| 8354510 | Hober et al. | Jan 2013 | B2 |
| 8377448 | Smith et al. | Feb 2013 | B2 |
| 8586713 | Davis et al. | Nov 2013 | B2 |
| 8617881 | Coljee et al. | Dec 2013 | B2 |
| 8674073 | Majima et al. | Mar 2014 | B2 |
| 8728479 | Greene et al. | May 2014 | B2 |
| 8772447 | Hall et al. | Jul 2014 | B2 |
| 8822642 | Levin et al. | Sep 2014 | B2 |
| 8853371 | Alfonso et al. | Oct 2014 | B2 |
| 8859726 | Bjorkman et al. | Oct 2014 | B2 |
| 8883134 | Cho et al. | Nov 2014 | B2 |
| 9018305 | Spector et al. | Apr 2015 | B2 |
| 9024000 | Jeon et al. | May 2015 | B2 |
| 9040661 | Nakamura et al. | May 2015 | B2 |
| 9051375 | Li et al. | Jun 2015 | B2 |
| 9073970 | Muller-Spath et al. | Jul 2015 | B2 |
| 9149738 | Skudas | Oct 2015 | B2 |
| 9156892 | Hober | Oct 2015 | B2 |
| 9187555 | Bjorkman et al. | Nov 2015 | B2 |
| 9266939 | Crine et al. | Feb 2016 | B2 |
| 9284347 | Eckermann et al. | Mar 2016 | B2 |
| 9290549 | Hall et al. | Mar 2016 | B2 |
| 9290573 | Cong et al. | Mar 2016 | B2 |
| 9296791 | Hober et al. | Mar 2016 | B2 |
| 9382305 | Wilmen et al. | Jul 2016 | B2 |
| 9481730 | Bruenker et al. | Nov 2016 | B2 |
| 9493529 | Blanche et al. | Nov 2016 | B2 |
| 9499608 | Chen et al. | Nov 2016 | B2 |
| 9517264 | Fachini et al. | Dec 2016 | B2 |
| 9534023 | Hober | Jan 2017 | B2 |
| 9540442 | Tsurushita et al. | Jan 2017 | B2 |
| 9556258 | Nti-Gyabaah et al. | Jan 2017 | B2 |
| 9573989 | Watzig et al. | Feb 2017 | B2 |
| 9587235 | Buechler et al. | Mar 2017 | B2 |
| 9637541 | Kim et al. | May 2017 | B2 |
| 9637557 | Scheer et al. | May 2017 | B2 |
| 9650442 | Hosse et al. | May 2017 | B2 |
| 9662373 | Cload et al. | May 2017 | B2 |
| 9676871 | Strop et al. | Jun 2017 | B2 |
| 9688978 | Buechler et al. | Jun 2017 | B2 |
| 9695233 | Duerr et al. | Jul 2017 | B2 |
| 9708405 | Liu et al. | Jul 2017 | B2 |
| 9714292 | Auer et al. | Jul 2017 | B2 |
| 9920098 | Yoshida et al. | Mar 2018 | B2 |
| 10065995 | Yoshida et al. | Sep 2018 | B2 |
| 20050097625 | Meade et al. | May 2005 | A1 |
| 20050143566 | Hober | Jun 2005 | A1 |
| 20060194955 | Hober et al. | Aug 2006 | A1 |
| 20080167450 | Pan | Jul 2008 | A1 |
| 20100221844 | Bian et al. | Sep 2010 | A1 |
| 20100267932 | Eon-Duval et al. | Oct 2010 | A1 |
| 20110117605 | Tolstrup et al. | May 2011 | A1 |
| 20110144311 | Chmielowski et al. | Jun 2011 | A1 |
| 20120071637 | Ambrosius et al. | Mar 2012 | A1 |
| 20120091063 | Bangtsson et al. | Apr 2012 | A1 |
| 20120149875 | Johansson et al. | Jun 2012 | A1 |
| 20120208234 | Yoshida et al. | Aug 2012 | A1 |
| 20120238730 | Dong et al. | Sep 2012 | A1 |
| 20120263722 | Ghayur et al. | Oct 2012 | A1 |
| 20120283416 | Frauenschuh et al. | Nov 2012 | A1 |
| 20130096276 | Yoshida et al. | Apr 2013 | A1 |
| 20130096284 | Ishihara | Apr 2013 | A1 |
| 20130197197 | Eckermann et al. | Aug 2013 | A1 |
| 20130274451 | Bjorkman et al. | Oct 2013 | A1 |
| 20140018525 | Goklen et al. | Jan 2014 | A1 |
| 20140031522 | Li et al. | Jan 2014 | A1 |
| 20140094593 | Frauenschuh | Apr 2014 | A1 |
| 20140100356 | Yoshida et al. | Apr 2014 | A1 |
| 20140107315 | Yoshida et al. | Apr 2014 | A1 |
| 20140148390 | Haupts et al. | May 2014 | A1 |
| 20140154270 | Wang et al. | Jun 2014 | A1 |
| 20140228548 | Galperina | Aug 2014 | A1 |
| 20140242624 | Valliere-Douglass et al. | Aug 2014 | A1 |
| 20140251911 | Skudas | Sep 2014 | A1 |
| 20140303356 | Gramer et al. | Oct 2014 | A1 |
| 20140329995 | Johansson et al. | Nov 2014 | A1 |
| 20150044209 | Brodt et al. | Feb 2015 | A1 |
| 20150080554 | Ander et al. | Mar 2015 | A1 |
| 20150093800 | Mahajan et al. | Apr 2015 | A1 |
| 20150133636 | Xenopoulos et al. | May 2015 | A1 |
| 20150140683 | Rueger et al. | May 2015 | A1 |
| 20150209445 | Maderna et al. | Jul 2015 | A1 |
| 20150210749 | Combs et al. | Jul 2015 | A1 |
| 20150218250 | Auer et al. | Aug 2015 | A1 |
| 20150368352 | Liu | Dec 2015 | A1 |
| 20160024147 | Tustian et al. | Jan 2016 | A1 |
| 20160053025 | Oh et al. | Feb 2016 | A1 |
| 20160083480 | Ng et al. | Mar 2016 | A1 |
| 20160090426 | Zhou et al. | Mar 2016 | A1 |
| 20160108084 | Gruber et al. | Apr 2016 | A1 |
| 20160145340 | Borges et al. | May 2016 | A1 |
| 20160152668 | Hober | Jun 2016 | A1 |
| 20160152725 | Cheung et al. | Jun 2016 | A1 |
| 20160158377 | Ackler et al. | Jun 2016 | A1 |
| 20160159855 | Rodrigo et al. | Jun 2016 | A1 |
| 20160159857 | Rodrigo et al. | Jun 2016 | A1 |
| 20160159929 | Lee et al. | Jun 2016 | A1 |
| 20160166634 | Caplan et al. | Jun 2016 | A1 |
| 20160200797 | Hall et al. | Jul 2016 | A1 |
| 20160237124 | Qian et al. | Aug 2016 | A1 |
| 20160251395 | Davis et al. | Sep 2016 | A1 |
| 20160272710 | Hilden et al. | Sep 2016 | A1 |
| 20160289335 | Weisser et al. | Oct 2016 | A1 |
| 20160296648 | Chevallier et al. | Oct 2016 | A1 |
| 20160304617 | Damle et al. | Oct 2016 | A1 |
| 20160310612 | Lyon et al. | Oct 2016 | A1 |
| 20160311853 | Geierstanger et al. | Oct 2016 | A1 |
| 20160340443 | Rossi et al. | Nov 2016 | A1 |
| 20160362474 | Wang et al. | Dec 2016 | A1 |
| 20160362500 | Knoetgen | Dec 2016 | A1 |
| 20170043033 | Strop et al. | Feb 2017 | A1 |
| 20170081412 | Newman et al. | Mar 2017 | A1 |
| 20170088596 | Scheer et al. | Mar 2017 | A1 |
| 20170096485 | Bacac et al. | Apr 2017 | A1 |
| 20170114141 | Amann et al. | Apr 2017 | A1 |
| 20170121282 | Geierstanger et al. | May 2017 | A1 |
| 20170152298 | Banerjee et al. | Jun 2017 | A1 |
| 20170165370 | Govindan et al. | Jun 2017 | A1 |
| 20170182179 | Ackler et al. | Jun 2017 | A1 |
| 20170204199 | Sanches et al. | Jul 2017 | A1 |
| 20170216452 | Ma et al. | Aug 2017 | A1 |
| 20170218051 | Gnauer et al. | Aug 2017 | A1 |
| 20170226172 | Mohammadi et al. | Aug 2017 | A1 |
| 20170233453 | Zheng et al. | Aug 2017 | A1 |
| 20170233490 | Bossenmaier et al. | Aug 2017 | A1 |
| 20170247417 | Chang et al. | Aug 2017 | A1 |
| 20170247467 | Amann et al. | Aug 2017 | A1 |
| 20170260265 | Duerr et al. | Sep 2017 | A1 |
| 20170260289 | Petersen et al. | Sep 2017 | A1 |
| 20170327534 | Rodrigo et al. | Nov 2017 | A1 |
| 20170334954 | Rodrigo et al. | Nov 2017 | A1 |
| 20190119318 | Rodrigo et al. | Apr 2019 | A1 |
| Number | Date | Country |
|---|---|---|
| 2202310 | Jun 2010 | EP |
| 2412809 | Feb 2012 | EP |
| 2557157 | Feb 2013 | EP |
| 2728000 | May 2014 | EP |
| 1608229.9 | May 2016 | GB |
| 1608232.3 | May 2016 | GB |
| 2006304633 | Nov 2006 | JP |
| 2010-081866 | Apr 2010 | JP |
| 8809344 | Dec 1988 | WO |
| 2003080655 | Oct 2003 | WO |
| 2005075507 | Aug 2005 | WO |
| 2008049106 | Apr 2008 | WO |
| 2011107518 | Sep 2011 | WO |
| 2011118699 | Sep 2011 | WO |
| 2012074463 | Jun 2012 | WO |
| 2012083425 | Jun 2012 | WO |
| 2012086660 | Jun 2012 | WO |
| 2012087231 | Jun 2012 | WO |
| 2012133349 | Oct 2012 | WO |
| 2013033517 | Mar 2013 | WO |
| 2013075849 | May 2013 | WO |
| 2013081540 | Jun 2013 | WO |
| 2013109302 | Jul 2013 | WO |
| 2013147691 | Oct 2013 | WO |
| 2014046278 | Mar 2014 | WO |
| 2014146350 | Sep 2014 | WO |
| 2014159064 | Oct 2014 | WO |
| 2014186350 | Nov 2014 | WO |
| 2014192877 | Dec 2014 | WO |
| 2015005859 | Jan 2015 | WO |
| 2015005862 | Jan 2015 | WO |
| 2015048330 | Apr 2015 | WO |
| 2015166072 | Nov 2015 | WO |
| 2016030791 | Mar 2016 | WO |
| 2016079033 | May 2016 | WO |
| 2016079033 | May 2016 | WO |
| 2016079034 | May 2016 | WO |
| 2016097300 | Jun 2016 | WO |
| 2017011342 | Jan 2017 | WO |
| 2017036805 | Mar 2017 | WO |
| 2017050889 | Mar 2017 | WO |
| Entry |
|---|
| Office Action Received for GB Patent Application No. 1608232.3, dated Mar. 1, 2017, 10 pages. |
| Hober et al.,“Protein A Chromatography for Antibody Purification”, Journal of Chromatography B, vol. 848, 2007, pp. 40-47. |
| Gulich et al., “Stability Towards Alkaline Conditions can be Engineered into a Protein Ligand”, Journal of Biotechnology, vol. 80, 2000, pp. 169-178. |
| International Search Report for PCT Application No. PCT/EP2017/061164, dated Aug. 30, 2017, 5 Pages. |
| International Search Report and Written Opinion Received for PCT Application No. PCT/EP2017/061158, dated Jul. 13, 2017, 15 Pages. |
| Uhlen et al., “Complete Sequence of the Staphylococcal Gene Encoding Protein A”, Journal of Biological Chemistry, vol. 259, No. 3, Feb. 10, 1984, pp. 1695-1702. |
| Hedhammar et al., “Protein Engineering Strategies for Selective Protein Purification”, Chemical Engineering Technology, vol. 28, No. 11, 2005, pp. 1315-1325. |
| Hober et al., “Protein A Chromotography for Antibody Purification”, Journal of Chromatography B, 848, 2007, pp. 40-47. |
| Altshul et al, “Basic Local Alignment Search Tool”, Journal of Molecular Biology, vol. 215, 1990, pp. 403-410. |
| U.S. Appl. No. 15/367,640, filed Dec. 2, 2016, 52 pages. |
| European Search Report from EP Appl. No. 17 728 070.8, dated Jul. 18, 2019. |
| Bostrom et al., “Purification Systems Based on Bacterial Surface Proteins,” Protein Purification, Intech, 2012, pp. 89-136, http://dx.doi.org/10.5772/31078 (50 pages). |
| Non-Final Office Action for U.S. Appl. No. 16/682,855, dated Dec. 5, 2019, 14 pages. |
| PCT International Search Report and Written Opinion for PCT Application No. PCT/EP2017/061164, dated Sep. 5, 2017 (10 pages). |
| PCT International Search Report and Written Opinion for PCT Application No. PCT/EP2015/076642, dated Apr. 20, 2016 (19 pages). |
| Singapore Written Opinion and Search Report for SG Application No. 112017030353P, dated May 3, 2018 (11 pages). |
| Russian Office Action for RU Application No. 2017115345/10, dated Apr. 2, 2019 (English translation, 19 pages). |
| Berry et al., “Substitution of Cysteine for Selenocysteine in Type 1 Iodothyronine Deiodinase Reduces the Catalytic Efficiency of the Protein but Enhances its Translation,” Endocrinology, 1992, 131(4): 1848-1852. |
| Gasser et al., “Antibody Production with Yeasts and Filamentous Fungi: On the Road to Large Scale?”, Biotechnol Lett, 2007, 29:201-212. |
| Pakula et al., “Genetic Analysis of Protein Stability and Function,” Annu. Rev. Genet, 1989, 23:289-310. |
| European Office Action for EP Application No. 15797942.8 dated Jun. 25, 2019 (4 pages). |
| JP Office Action for JP Application No. 2017-525398 dated Nov. 11, 2019 (8 pages, English translation). |
| PCT International Search Report and Written Opinion for PCT Application No. PCT/EP2017/061162 dated Sep. 11, 2017 (24 pages). |
| Gel Filtration Principles and Methods, Pharmacia LKB Biiotechnology 1991, pp. 6-13. |
| Australian Office Examination Report No. 1 for AU Application No. 2015348641 dated Dec. 17, 2019 (12 pages). |
| International Search Report for PCT Application No. PCT/EP2017/061160, dated Aug. 25, 2017, 5 pages. |
| GB Search Report for GB Application No. 1608229.9 dated Feb. 28, 2017, (10 pages). |
| GB Search Report for GB Application No. 1608232.3 dated Mar. 1, 2017 (10 pages). |
| Arshady, “Styrene Based Polymer Supports Developed by Suspension Polymerization,” Chimica e L'Industria, 1988, 70:(9): 70-75. |
| Hjerten, “The Preparation of Agarose Spheres for Chromatography of Molecules and Particles,” Biochim. Boiphys. Acta, 1964, 79:L393-398. |
| Bach et al., “Differential binding of heavy chain variable domain 3 antigen binding fragments to protein a chromatography resins,” J Chromatography A, 2015, 1409: 60-69. |
| O'Seaghdha et al., “Staphylococcus aureus protein A binding to von Villebrand factor A1 domain is mediated by conserved IgG binding regions,” FEBS J, 2006, 273, pp. 4831-4841. |
| Pakiman et al., “Comparison of Binding Capacity and Affinity of Monoclonal Antibody towards Different Affinity Resins using High-throughput Chromatography Method,” J Appl Sci, 2012, 12, 11, pp. 1136-1141. |
| Weidle et al., “The intriguing options of multispecific antibody formats for treatment of cancer,” Cancer Genom. Proteom, 2013, 10, pp. 1-18. |
| International Search Report for PCT Application No. PCT/EP2015/076639, dated Feb. 10, 2016 (12 pages). |
| International-type Search Report for ITS/SE2014/000256, dated May 13, 2015 (5 pages). |
| International Search Report and Written Opinion for PCT/EP2017/061159, dated Aug. 1, 2017 (14 pages). |
| Number | Date | Country | |
|---|---|---|---|
| 20170327534 A1 | Nov 2017 | US |
