US20160347787A1

US20160347787A1 - Use of cation-exchange chromatography in the flow-through mode to enrich post-translational modifications

Info

Publication number: US20160347787A1
Application number: US15/116,456
Authority: US
Inventors: Austen NG; Robert S. GRONKE
Original assignee: Biogen MA Inc
Current assignee: Biogen MA Inc
Priority date: 2014-02-04
Filing date: 2015-02-04
Publication date: 2016-12-01
Also published as: KR20230136616A; WO2015120056A1; KR20160117562A; KR102382402B1; US20220306684A1; EP3102589A1; IL246912B; AU2015214245B2; KR102567586B1; IL292150A; AU2015214245A1; JP2017505780A; NZ722391A; KR20220044391A; JP6609561B2; IL246912A0

Abstract

The present invention relates to improved methods in the separation recombinant polypeptides with post-translational modifications from complex mixtures through the use of a cation exchange medium.

Description

BACKGROUND OF THE INVENTION

Specific post-translational modifications and impurity levels are often mandated by regulatory agencies for recombinant polypeptides intended for human administration. Often the level of post-translational modifications of recombinant polypeptides produced in cell lines in vitro differs from the level of post-translational modifications required for recombinant polypeptides intended for human administration. The glycosylation profile of a polypeptide can be affected by multiple factors including the type of production cell line, the growth conditions and the polypeptide sequence. Shiestl, M., et al. Nature Biotechnology 29(4):310 (2011).
There is a need in the art for methods that provide for enrichment of recombinant polypeptides with specific levels of particular post-translational modifications on a scale that is amenable for manufacturing processes, i.e. that maintains an acceptable product recovery and yield.

SUMMARY OF THE INVENTION

The present invention provides a method for enriching the level of post-translational modification of recombinant polypeptides, comprising: contacting a composition which comprises an initial population of recombinant polypeptides having different levels of post-translational modification with a cation exchange chromatography (CEX) medium operated in a flow-through mode; wherein recombinant polypeptides that do not bind the CEX medium are separated from recombinant polypeptides that bind the CEX medium, and wherein the recombinant polypeptides that do not bind the CEX medium comprise a higher level of post-translational modification compared to the bound recombinant polypeptides.
The present invention provides a method for enriching the level of post-translational modification of recombinant polypeptides, comprising:

- a) contacting a composition which comprises an initial population of recombinant polypeptides having different levels of post-translational modification with a cation exchange chromatography (CEX) medium operated in a flow-through mode; and
- b) separating recombinant polypeptides that do not bind the CEX medium from recombinant polypeptides that bind the CEX medium;
  wherein the recombinant polypeptides that do not bind the CEX medium that are recovered comprise a higher level of post-translational modification compared to the bound recombinant polypeptides.

The present invention provides a method for enriching the level of post-translational modification of recombinant polypeptides, comprising:

- a) contacting a composition which comprises an initial population of recombinant polypeptides having different levels of post-translational modification with a cation exchange chromatography (CEX) medium operated in a flow-through mode;
- b) separating recombinant polypeptides that do not bind the CEX medium from recombinant polypeptides that bind the CEX medium; and
- c) recovering the recombinant polypeptides that do not bind the CEX medium;
  wherein the recombinant polypeptides that do not bind the CEX medium comprise a higher level of post-translational modification compared to the bound recombinant polypeptides.

- a) providing a composition which comprises an initial population of recombinant polypeptides having different levels of post-translational modification;
- b) contacting the composition with a cation exchange chromatography (CEX) medium operated in a flow-through mode;
- c) separating recombinant polypeptides that do not bind the CEX medium from recombinant polypeptides that bind the CEX medium; and
- d) recovering the recombinant polypeptides that do not bind the CEX medium;
  wherein the recombinant polypeptides that do not bind the CEX medium comprise a higher level of post-translational modification compared to the bound recombinant polypeptides.

In some embodiments, the method further provides recovering the recombinant polypeptides that do not bind the CEX medium.
In some embodiments, the post-translational modification is sialylation or gamma-carboxyglutamate (Gla) formation. In some embodiments, the post-translational modification is sialylation.
In some embodiments, the total sialic acid content of the recombinant polypeptides that do not bind the CEX medium is between about 0.5 and about 6 moles of sialic acid per mole of protein higher than that of the initial population of recombinant polypeptides. In some embodiments, the total sialic acid content of the recombinant polypeptides that do not bind the CEX medium is between about 0.5 and about 4 moles of sialic acid per mole of protein higher than that of the initial population of recombinant polypeptides. In some embodiments, the total sialic acid content of the recombinant polypeptides that do not bind the CEX medium is between about 5% and about 100% higher than that of the initial population of recombinant polypeptides. In some embodiments, the total sialic acid content of the recombinant polypeptides that do not bind the CEX medium is between about 5% and about 40% higher than that of the initial population of recombinant polypeptides. In some embodiments, the total sialic acid content of the recombinant polypeptides that do not bind the CEX medium is between about 12 and about 20 moles of sialic acid per mole of protein. In some embodiments, the total sialic acid content of the recombinant polypeptides that do not bind the CEX medium is between about 14 and about 17 moles of sialic acid per mole of protein.
In some embodiments, the total sialic acid content of the initial population of recombinant polypeptides is about 10 to about 14 moles of sialic acid per mole of protein. In some embodiments, the total sialic acid content of the initial population of recombinant polypeptides is about 13-14 moles of sialic acid per mole of protein.
In some embodiments, the recombinant polypeptide comprises an Fc domain. In some embodiments, the recombinant polypeptide comprises an antibody.
In some embodiments, the recombinant polypeptide comprises an Fc fusion polypeptide comprising a ligand binding domain of a receptor. In a specific embodiment, the receptor is a TNF receptor. In a more specific embodiment, the recombinant polypeptide is etanercept.
In some embodiments, the recombinant polypeptide comprises a clotting factor. In some embodiments, the recombinant polypeptide is a monomer-dimer hybrid. Examples of clotting factors include Factor VII (FVII), FVIIa, Factor VIII (FVIII), Factor IX (FIX), or FIXa (FIX). FVIII can be full-length FVIII or B-domain deleted FVIII. FVIII can be single chain FVIII or dual chain FVIII.
In some embodiments, the contacting occurs at a load ratio between about 30 and about 100 mg total protein/ml CEX medium. In some embodiments, the contacting occurs at a load ratio between about 33 and about 54 mg total protein/ml CEX medium. In some embodiments, the contacting occurs at a load ratio of at least about 41 mg total protein/ml CEX medium.
In some embodiments, the contacting occurs at a pH between about 4 and about 7. In some embodiments, the contacting occurs at a pH between about 5 and about 6. In some embodiments, the contacting occurs at a pH between about 5.5 and about 5.8 In some embodiments, the contacting occurs at a pH of at least about 5.6.
In some embodiments, the contacting occurs at a conductivity between about 8 and about 12 mS/cm. In some embodiments, the contacting occurs at a conductivity of between about 9.5 and about 11 mS/cm. In some embodiments, the contacting occurs at a conductivity of at least about 10 mS/cm.
In some embodiments, the recombinant polypeptides that do not bind the CEX medium comprise about 25% to about 80% of the initial population of recombinant polypeptides. In some embodiments, the recombinant polypeptides that do not bind the CEX medium comprise about 55% to about 80% of the initial population of recombinant polypeptides.
In some embodiments, the CEX medium comprises one of the following ligands: sulfoethyl; sulphopropyl; sulfopropyl; CH₂—SO₃ ⁻; CH₂CH₂CH₂SO₃ ⁻; SO₃ ⁻; or CH₂—COO⁻. In some embodiments, the CEX medium comprises a sulfoethyl ligand.
In some embodiments, the CEX medium comprises a binding capacity of between about 120 and about 160 mg lysozyme/ml resin.
In some embodiments, the recombinant polypeptide is produced by a eukaryotic host cell. In specific embodiments, the eukaryotic host cell is a mammalian host cell.
In some embodiments, the contacting is performed at a manufacturing scale.
In some embodiments, the composition further comprises at least one impurity. Examples of impurities include a DNA, RNA, lipid or protein. In some embodiments, the impurity comprises a protein. Examples of the protein impurities include a truncated form of the recombinant polypeptide, an aggregated form of the recombinant polypeptide, or a misfolded form of the recombinant polypeptide.
In some embodiments, the method provides a final composition comprising the recombinant polypeptides that do not bind the CEX medium, wherein the final composition comprises less impurities than the composition that comprised the initial population of polypeptides.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 illustrates a SE Hicap Chromatogram for the enrichment of sialylated etanercept. The load ratio was 31 mg/ml, the load pH was 5.6, and the load conductivity was 10 mS/cm. The product yield was 67%, and the total sialic acid of the product was 15 moles of sialic acid/mole of protein. Peak 1 is composed of clipped etanercept. Peak 2 is composed of native etanercept. Peak 3 is composed of misfolded etanercept.

FIG. 2 illustrates a comparison of the TSA enrichment of etanercept by various CEX resins (SE Hicap, SP Sepharose, SP Sepharose XL, Nuvia S, Eshmuno, GigaCap S, and GigaCap CM). The results were normalized to 50% product yield.

FIG. 3 illustrates a comparison of the impurities removed from a composition comprising etanercept by various CEX resins (SE Hicap, SP Sepharose, SP Sepharose XL, Nuvia S, Eshmuno, GigaCap S, and GigaCap CM). The results were normalized to 50% product yield.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to methods of enriching the level of post-translational modifications of recombinant polypeptides through the use of a chromatography medium. In preferred embodiments, the chromatography medium is an ion exchange chromatography medium utilized in a flow-through mode of operation.
In order to provide a clear understanding of the specification and claims, the following definitions are provided below.

DEFINITIONS

It is to be noted that the term “a” or “an” entity refers to one or more of that entity; for example, “a nucleotide sequence,” is understood to represent one or more nucleotide sequences. As such, the terms “a” (or “an”), “one or more,” and “at least one” can be used interchangeably herein.
Furthermore, “and/or” where used herein is to be taken as specific disclosure of each of the two specified features or components with or without the other. Thus, the term “and/or” as used in a phrase such as “A and/or B” herein is intended to include “A and B,” “A or B,” “A” (alone), and “B” (alone). Likewise, the term “and/or” as used in a phrase such as “A, B, and/or C” is intended to encompass each of the following aspects: A, B, and C; A, B, or C; A or C; A or B; B or C; A and C; A and B; B and C; A (alone); B (alone); and C (alone).
It is understood that wherever aspects are described herein with the language “comprising,” otherwise analogous aspects described in terms of “consisting of” and/or “consisting essentially of” are also provided.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure is related. For example, the Concise Dictionary of Biomedicine and Molecular Biology, Juo, Pei-Show, 2nd ed., 2002, CRC Press; The Dictionary of Cell and Molecular Biology, 3rd ed., 1999, Academic Press; and the Oxford Dictionary Of Biochemistry And Molecular Biology, Revised, 2000, Oxford University Press, provide one of skill with a general dictionary of many of the terms used in this disclosure.
Units, prefixes, and symbols are denoted in their Système International de Unites (SI) accepted form. Numeric ranges are inclusive of the numbers defining the range. Unless otherwise indicated, amino acid sequences are written left to right in amino to carboxy orientation. The headings provided herein are not limitations of the various aspects of the disclosure, which can be had by reference to the specification as a whole. Accordingly, the terms defined immediately below are more fully defined by reference to the specification in its entirety.
The term “about” is used herein to mean approximately, roughly, around, or in the regions of. When the term “about” is used in conjunction with a numerical range, it modifies that range by extending the boundaries above and below the numerical values set forth. In general, the term “about” can modify a numerical value above and below the stated value by a variance of, e.g., 10 percent, up or down (higher or lower).
As used herein, the term “protein” or “polypeptide” refers to a polymer of two or more of the natural amino acids or non-natural amino acids.
Polypeptides may be either monomers or multimers. For example, in one embodiment, a protein of the invention is a dimer. A dimeric polypeptide of the invention may comprise two polypeptide chains or may consist of one polypeptide chain (e.g., in the case of a scFc molecule). In one embodiment, the dimers of the invention are homodimers, comprising two identical monomeric subunits or polypeptides (e.g., two identical Fc moieties or two identical biologically active moieties). In another embodiment, the dimers of the invention are heterodimers, comprising two non-identical monomeric subunits or polypeptides (e.g., comprising two different clotting factors or portions thereof or one clotting factor only). See, e.g., U.S. Pat. No. 7,404,956, incorporated herein by reference in its entirety.
“Recombinantly expressed polypeptide” and “recombinant polypeptide” refer to a polypeptide expressed from a host cell that has been genetically engineered to express that polypeptide. The recombinantly expressed polypeptide can be identical or similar to polypeptides that are normally expressed in the mammalian host cell. The recombinantly expressed polypeptide can also foreign to the host cell, i.e. heterologous to peptides normally expressed in the mammalian host cell. Alternatively, the recombinantly expressed polypeptide can be chimeric in that portions of the polypeptide contain amino acid sequences that are identical or similar to polypeptides normally expressed in the mammalian host cell, while other portions are foreign to the host cell. Any polypeptide that is expressible in a host cell may be produced in accordance with the present invention. The polypeptide may be expressed from a gene that is endogenous to the host cell, or from a gene that is introduced into the host cell through genetic engineering. The polypeptide may be one that occurs in nature, or may alternatively have a sequence that was engineered or selected by the hand of man. An engineered polypeptide may be assembled from other polypeptide segments that individually occur in nature, or may include one or more segments that are not naturally occurring. Polypeptides that may desirably be expressed in accordance with the present invention will often be selected on the basis of an interesting biological or chemical activity. For example, the present invention may be employed to express any pharmaceutically or commercially relevant enzyme, receptor, antibody, hormone, regulatory factor, antigen, binding agent, etc. . . . .
Polypeptides that are “variants” of another peptide may have one or more mutations relative to the starting polypeptide, e.g., one or more amino acid residues which have been substituted with another amino acid residue or which has one or more amino acid residue insertions or deletions. In one embodiment, the polypeptide comprises an amino acid sequence which is not naturally occurring. Such variants necessarily have less than 100% sequence identity or similarity with the starting polypeptide. In another embodiment, the variant will have an amino acid sequence from about 75% to less than 100% amino acid sequence identity or similarity with the amino acid sequence of the starting polypeptide, for example, from about 80% to less than 100%, from about 85% to less than 100%, from about 90% to less than 100% (e.g., 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%) and from about 95% to less than 100%, e.g., over the length of the variant molecule. In one embodiment, there is one amino acid difference between a starting polypeptide sequence and the sequence derived therefrom. Identity or similarity with respect to this sequence is defined herein as the percentage of amino acid residues in the candidate sequence that are identical (i.e. same residue) with the starting amino acid residues, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity.
A “fusion” or “chimeric” protein comprises a first amino acid sequence linked to a second amino acid sequence with which it is not naturally linked in nature. The amino acid sequences which normally exist in separate proteins can be brought together in the fusion polypeptide, or the amino acid sequences which normally exist in the same protein can be placed in a new arrangement in the fusion polypeptide, e.g., fusion of a Factor VIII domain of the invention with an Ig Fc domain. A fusion protein is created, for example, by chemical synthesis, or by creating and translating a polynucleotide in which the peptide regions are encoded in the desired relationship. A chimeric protein can further comprises a second amino acid sequence associated with the first amino acid sequence by a covalent, non-peptide bond or a non-covalent bond.
The term “aggregates”, as used herein, refers to polypeptide aggregates. It encompasses multimers (such as dimers, tetramers or higher order aggregates) of the recombinant polypeptide to be purified and may result, e.g., in high molecular weight aggregates.
The term “chromatography” refers to any kind of technique which separates a recombinant polypeptide of interest from other molecules present in a mixture. Usually the recombinant polypeptide of interest is separated from other molecules as a result of differences in binding affinity.
The term “binding” a molecule to a chromatography resin means exposing the molecule to chromatography resin under appropriate conditions (e.g. pH/conductivity) such that the molecule is reversibly immobilized in or on the chromatography resin by virtue of ligand-protein interactions. Non-limiting examples include ionic interactions between the molecule and a charged group or charged groups of the ion exchange material and an immunoglobulin.
The terms “flow-through,” “flow-through process,” “flow-through mode,” and “flow-through chromatography,” as used interchangeably herein, refer to a product separation technique in which at least one product (e.g., a recombinant polypeptide with specific post-translational modifications) contained in a sample is intended to flow-through a chromatographic resin or media, while at least one potential contaminant or impurity binds to the chromatographic resin or media.
The terms “chromatography resin”, “chromatography media” and “chromatography medium” are used interchangeably and refer to any kind of solid phase which separates a recombinant polypeptide of interest from other molecules present in a mixture. Usually, the recombinant polypeptide of interest is separated from other molecules as a result of differences in binding affinity between the other molecules in the mixture and the recombinant polypeptide of interest. use of any known, or subsequently disclosed or developed, chromatography media or matrix. Examples, without limitation, of such media comprise: ion exchange media; anion exchange media; cation exchange media; hydroxyapatite media; hydrophobic interaction chromatography media; antibody-affinity media (e.g., Protein-A or variants thereof); immunoglobulin Fc-region affinity media (e.g., Fc-receptor affinity media); and, ligand-affinity media; receptor-affinity media; and mixed-mode media.
As used herein the terms “ion-exchange” and “ion-exchange chromatography” are used to refer to a chromatographic process in which a recombinant polypeptide of interest interacts or does not interact with a charged compound linked (such as by covalent attachment) to a solid phase ion exchange material such that the recombinant polypeptide of interest interacts non-specifically with the charged compound more or less than other recombinant polypeptides or impurities in the mixture. The contaminant in the mixture elutes from a column of the ion exchange material faster or slower than the recombinant polypeptide of interest or are bound to or excluded from the resin relative to the recombinant polypeptide of interest. “Ion-exchange chromatography” specifically includes cation exchange, anion exchange, and mixed mode ion exchange chromatography.
The “pI” or “isoelectric point” of a polypeptide refer to the pH at which the polypeptide's positive charge balances its negative charge, pI can be calculated from the net charge of the amino acid residues or sialic acid residues of attached carbohydrates of the polypeptide or can be determined by isoelectric focusing.
The phrase “ion exchange material” refers to a solid phase that is negatively charged (i.e., a cation exchange resin) or positively charged (i.e., an anion exchange resin). The charge may be provided by attaching one or more charged ligands to the solid phase, e.g., by covalent linking. Alternatively, or in addition, the charge may be an inherent property of the solid phase (e.g., as is the case for silica, which has an overall negative charge).
The phrase “anion exchange resin” or “AEX” refers to a solid phase which is positively charged, e.g., having one or more positively charged ligands, such as quaternary amino groups, attached thereto. Commercially available anion exchange resins include DEAE cellulose, QAE SEPHADEX™ and FAST Q SEPHAROSE™ (Pharmacia). Anion exchange chromatography can bind the target molecule (e.g., an Fc region containing target protein) followed by elution or can predominately bind the impurities while the target molecule “flows through” the column.
The phrase “cation exchange resin” or “CEX” refers to a solid phase which is negatively charged, and which thus has free cations for exchange with cations in an aqueous solution passed over or through the solid phase. A negatively charged ligand attached to the solid phase to form the cation exchange resin may, e.g., be a carboxylate or sulfonate. For example, cation exchange chromatography can be performed under conditions in which the resin bind the target molecule (e.g., an Fc region containing target protein) followed by elution (cation exchange bind and elution chromatography or “CIEX”). Alternatively, CEX can be run in a mode which it predominately binds the impurities while the target molecule “flows through” the column (cation exchange flow-through chromatography). Commercially available CEX resins include Fractogel SE Hicap, GE SPXL, GE SP Sepharose, Millipore Eshmuno S, Tosoh Gigacap CM, Tosoh Gigacap S-650, or BioRad Nuvia S. The phrase “cation exchange resin” or “CEX” also refers to a mixed-mode resin that is partially or entirely operated in cation-exchange mode of chromatography. Commercially available mixed-mode resins include Capto MMC. The purification method disclosed herein utilizes a cation exchange chromatography step which is performed in a flow-through mode.

Chromatography Methods

The present invention utilizes a “flow-through” mode of operation wherein a recombinant polypeptide is allowed to contact a chromatography medium (or other matrix). During the contacting, a recombinant polypeptide having a selected characteristic (such as a particular post-translational modification) preferentially does not bind to the chromatography medium (or other matrix) while recombinant polypeptides (as well as other impurities) not having the selected characteristic, or having less of the selected characteristic (such as a recombinant polypeptide having a lower overall net negative charge or a lower sialic acid content) binds to the medium (or matrix). The flow-through, containing the enriched recombinant polypeptide, is recovered. The recombinant polypeptide mixture obtained is enriched with a higher concentration of product having the selected (target) characteristic compared to the composition containing the initial population of recombinant polypeptides prior to contacting with the chromatography medium.
In some embodiments, the present invention is directed to selectively enriching recombinant polypeptides wherein the selected or desired product characteristic is that of having increased or enhanced overall (total) levels of sialic acid content. In some embodiments, a recombinant polypeptide with increased total sialic acid content is obtained by contacting a composition that contains a population of exchange chromatography medium (e.g., SE Hicap) with a mixture of the recombinant polypeptide. Undesired products (e.g., product with a lower sialic acid content, and other impurities) are allowed to bind the chromatography medium, then the selected product (with high sialic acid content) flows through the column and is recovered.
Methods of the present invention can be adapted and applied to the separation/purification of recombinant polypeptides based on any number of physical, biological, and/or chemical characteristics. For example, product isoforms may be selectively separated on the basis of charge and/or hydrophobicity by using appropriate adsorbents (such as, for example, strong or weak cation exchange resins for charge based separations and hydrophobic adsorbents for separations based on hydrophobicity). Additionally, methods of the invention may be applied using mixed-mode chromatography (mixed-mode media) for separations based on two orthogonal product attributes (e.g., charge and hydrophobicity).
In some embodiments, the invention relates to a method for enriching, increasing, enhancing, or augmenting the level of post-translational modification of recombinant polypeptides comprising: contacting a composition which comprises an initial population of recombinant polypeptides having different levels of post-translational modification with a cation exchange chromatography (CEX) medium operated in a flow-through mode; wherein recombinant polypeptides that do not bind the CEX medium are separated from recombinant polypeptides that bind the CEX medium, and wherein the recombinant polypeptides that do not bind the CEX medium comprise a higher or increased level of post-translational modification compared to the bound recombinant polypeptides.
In some embodiments, the recombinant polypeptides that do not bind the CEX medium are more negatively charged than the polypeptides or other impurities that bind the CEX resin. In some embodiments, the invention further comprises recovering the recombinant polypeptides that do not bind the CEX medium.
In some embodiments, recombinant polypeptides with higher levels of specific post-translational modifications are separated from recombinant polypeptides with lower levels of post-translational modifications through the use of a CEX medium operated in flow-through mode. “Separating” refers to increasing the degree of purity of a recombinant polypeptide of interest from a composition or sample comprising the polypeptide and one or more impurities or contaminants. In some embodiments, the recombinant polypeptide of interest is separated from the other polypeptides or impurities in the composition through the use of charge. In some embodiments, the recombinant polypeptide of interest is more negatively charged than other polypeptides or impurities in the composition such that the recombinant polypeptide of interest does not bind to the CEX medium operated in flow-through mode. In some embodiments, the degree of purity of the recombinant polypeptide of interest is increased by removing (completely or partially) at least one impurity from the composition. In some embodiments, the post-translational modification is sialylation or gamma-carboxyglutamate (Gla) formation.
In some embodiments, the post-translational modification is sialylation. Sialylation is the final step of human glycosylation. Total sialic residue refers to the total number of sialic residues on a given recombinant polypeptide. The sialylation of a protein is critical to protein function, as the in vivo biological activity of glycosylated proteins is known to be dependent on the number of sialic acid units per molecule. Shiestl, M., et al. Nature Biotechnology 29(4):310 (2011). The loss of sialic acid frequency leads to reduced glycoprotein solubility and reduced circulatory half-life. As a result the purification and therapeutic effectiveness of a recombinant polypeptide is dependent on the sialic acid content. The glycosylation profile of a polypeptide can be affected by many factors including the type of production cell line, the growth conditions, and the polypeptide sequence. Shiestl, M., et al. Nature Biotechnology 29(4):310 (2011).
In some embodiments, the total sialic acid content of the recombinant polypeptide is between about 0.5 and about 6, between about 1 and about 4, or between about 1 and about 3 moles of sialic per mole of protein higher than that of the initial population of recombinant polypeptides. In some embodiments, the total sialic acid content of the recombinant polypeptide is between about 0.6 and about 2.7 moles of sialic per mole of protein higher than that of the initial population of recombinant polypeptides. In some embodiments, the total sialic acid content of the recombinant proteins is at least about 0.5, at least about 1.0, at least about 1.5, at least about 2.0, at least about 2.5, at least about 3.0, at least about 3.5, at least about 4.0, at least about 4.5, at least about 5.0, at least about 5.5, or at least about 6.0 moles of sialic per mole of protein higher than that of the initial population of recombinant polypeptides.
In some embodiments, the total sialic content of the recombinant polypeptides that do not bind the CEX medium is between about 5% and about 100%, between about 5% and about 90%, between about 5% and about 80%, between about 5% and about 70%, between about 5% and about 60%, between about 5% and about 50%, and between about 5% and about 40% higher than that of the composition containing the initial population of recombinant polypeptides. In some embodiments, the total sialic content of the recombinant polypeptides that do not bind the CEX medium is at least about 5%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 99% or at least about 100% higher than that of the composition containing the initial population of recombinant polypeptides.
In some embodiments, the total sialic acid content of the recombinant polypeptides that do not bind the CEX medium is between about 13 and about 20, between about 13.5 and about 19, between about 14 and about 18, between about 14 and about 17, or between about 14 and about 16.5 moles of sialic acid per mole of protein. In some embodiments, the total sialic acid content of the recombinant polypeptides that do not bind the CEX medium is between about 14.1 and about 16.2.
In some embodiments, the total sialic content of the initial content of the initial population of recombinant polypeptides is between about 10 and about 14, between about 10.5 and about 14, between about 11 and about 14, between about 11.5 and about 14, between about 12 and about 14, between about 12.5 and about 14, or between about 13 and about 14 moles of sialic acid per mole of protein. In some embodiments, the total sialic acid content of the initial population of recombinant polypeptides is at least about 10, at least about 10.5, at least about 11, at least about 11.5, at least about 12, at least about 12.5, at least about 13, at least about 13.5 or at least about 14 moles of sialic acid per mole of protein. In some embodiments, the total sialic acid content of the initial population of recombinant polypeptides is at least about 13.5 moles of sialic acid per mole of protein.
In some embodiments, the post-translational modification is gamma-carboxyglutamate (Gla) formation. The carboxylation/gamma-carboxyglutamic (GLA) domain is a Vitamin-K dependent domain. At the GLA domain, Vitamin K mediates the carboxylation of glutamate residues to form gamma-carboxyglutamate (Gla). Vermeer, C. Biochem J. 266: 625-636 (1990). Gla plays a key role in calcium binding, and has been found to be critical for specific conformational transitions in clotting factor proteins. Freedman, S. J. et al., J. Biol. Chem. 271(27): 16227-36 (1996).
In some embodiments, the Gla content of the recombinant polypeptides that do not bind the CEX medium is between about 5% and about 100%, between about 5% and about 90%, between about 5% and about 80%, between about 5% and about 70%, between about 5% and about 60%, between about 5% and about 50%, and between about 5% and about 40% higher than that of the initial population of recombinant polypeptides.
In some embodiments, the total Gla content of the recombinant polypeptides that do not bind the CEX medium is between about 5% and about 100%, between about 5% and about 90%, between about 5% and about 80%, between about 5% and about 70%, between about 5% and about 60%, between about 5% and about 50%, and between about 5% and about 40% higher than that of the initial population of recombinant polypeptides.
In some embodiments of the invention, a chromatography medium in “flow-through” mode of operation is utilized to enrich a composition of recombinant polypeptides having a specific post-translational modification.
The load ratio describes the total amount of the composition that is contacting the chromatography medium per volume of medium. If the load ratio is too high, then, in the case of a column run in flow-through mode, some impurities may not bind the medium. In some embodiments, the contacting of the composition with the medium occurs at a load ratio of at least about 30 mg total protein/ml CEX medium, at least about 35 mg total protein/ml CEX medium, at least about 40 mg total protein/ml CEX medium, at least about 45 mg total protein/ml CEX medium, at least about 50 mg total protein/ml CEX medium, at least about 55 mg total protein/ml CEX medium, at least about 60 mg total protein/ml CEX medium, at least about 70 mg total protein/ml CEX medium, at least about 80 mg total protein/ml CEX medium, at least about 90 mg total protein/ml CEX medium, at least about 100 mg total protein/ml CEX medium, at least about 110 mg total protein/ml CEX medium, at least about 120 mg total protein/ml CEX medium, at least about 130 mg total protein/ml CEX medium, at least about 140 mg total protein/ml CEX medium, or at least about 150 mg total protein/ml CEX medium. In some embodiments, the contacting occurs at a load ratio of 41 mg total protein/ml CEX medium. In some embodiments, the contacting of the composition with the medium occurs at a load ratio of between about 30 mg total protein/ml CEX medium and about 150 mg total protein/ml CEX medium, between about 30 mg total protein/ml CEX medium and 125 mg total protein/ml CEX medium, between about 30 mg total protein/ml CEX medium and 100 mg total protein/ml CEX medium, between about 30 mg total protein/ml CEX medium and 75 mg total protein/ml CEX medium, between about 30 mg total protein/ml CEX medium and 60 mg total protein/ml CEX medium, or between about 33 mg total protein/ml CEX medium and 54 mg total protein/ml CEX medium.
The pH of the contacting step is critical because it determines which charged molecules will bind the column and which will not bind. In some embodiments, the contacting of the composition with the medium occurs at a pH of at least about 3, at least about 4, at least about 5, at least about 5.5, at least about 6, at least about 6.5, at least about 7, at least about 8 or at least about 9. In some embodiments, the contacting occurs at a pH of 5.6. In some embodiments, the contacting of the composition with the medium occurs at a pH between about 3 and about 9, between about 4 and about 8, between about 4 and about 7, between about 5 and about 7, between about 5 and about 6, or between about 5.5 and about 5.8.
The conductivity of the contacting step is critical because it determines which molecules will bind the column and which will not bind. In some embodiments, the contacting of the composition with the medium occurs at a conductivity of at least about 8 mS/cm, at least about 8.5 mS/cm, at least about 9 mS/cm, at least about 10 mS/cm, at least about 10.5 mS/cm, at least about 11 mS/cm, at least about 11.5 mS/cm, at least about 12 mS/cm, at least about 12.5 mS/cm, or at least about 13 mS/cm. In some embodiments the contacting occurs at a conductivity of 10 mS/cm. In some embodiments the contacting occurs at a conductivity of between about 8 mS/cm and about 12 mS/cm, between about 8.5 mS/cm and 11.5 mS/cm, between about 9 mS/cm and about 11.5 mS/cm, between about 9 mS/cm and about 11 mS/cm, or between about 9.5 mS/cm and 11 mS/cm.
In some embodiments, the chromatography medium is ion exchange media; anion exchange media; cation exchange media; hydroxyapatite media; hydrophobic interaction chromatography media; antibody-affinity media (e.g., Protein-A or variants thereof); immunoglobulin Fc-region affinity media (e.g., Fc-receptor affinity media); and, ligand-affinity media; receptor-affinity media; or mixed-mode media. In preferred embodiments, the chromatography medium is a CEX resin. Embodiments of the invention include use of any known, or subsequently disclosed or developed, CEX chromatography media or matrix. In some embodiments, the CEX resin is a Fractogel SE Hicap, GE SPXL, GE SP Sepharose, Millipore Eshmuno S, Tosoh Gigacap CM, Tosoh Gigacap S-650, BioRad Nuvia S, or Capto MMC. In some embodiments, the CEX medium comprises a ligand that is sulfoethyl; sulphopropyl; sulfopropyl; CH₂—SO₃; CH₂CH₂CH₂SO₃ ⁻; SO₃ ⁻; CH₂—COO⁻; or a multimodal weak cation exchanger. In some embodiments, the CEX medium comprises a matrix that is: crosslinked polymethacrylate, 6% cross-linked agarose with dextran surface extenders, agarose, surface grafted rigid polyvinyl ether hydrophilic polymer, or highly cross-linked agarose. In some embodiments, the CEX medium is any known matrix. In some embodiments, the CEX medium comprises a sulfoethyl ligand. In some embodiments, the CEX resin is Fractogel SE Hicap.
In some embodiments, the CEX medium comprises a binding capacity or ligand capacity of between about 100 and about 200 mg lysozyme/ml resin, between about 110 and 190 mg lysozyme/ml resin, between about 120 and about 180 mg lysozyme/ml resin, between about 120 and about 170 mg lysozyme/ml resin, between about 120 and about 160 mg lysozyme/ml resin, or between about 125 and 160 mg lysozyme/ml resin.
The ion exchange rate between the medium and the composition increases as the temperature increases. Temperature can also affect the selectivity of the column. In some embodiments, the temperature during the contacting of the composition with the medium is between about 16 and about 26° C., between about 18 and about 24° C., or between about 20 and about 23° C. In some embodiments, the temperature during the contacting of the composition with the medium is at least about 15° C., at least about 16° C., at least about 17° C., at least about 18° C., at least about 19° C., at least about 20° C., at least about 21° C., at least about 22° C., at least about 23° C., at least about 24° C., at least about 25° C., at least about 26° C. or at least about 30° C. In some embodiments, the temperature during the contacting of the composition with the medium is about 22° C.
A higher flow rate decreases the process time, but a higher flow rate may decrease the efficiency of separation, due to decreased contacting time between the composition and the medium. In some embodiments, the process flow rate is between about 75 cm/hr and about 150 cm/hr, between about 100 cm/hr and about 150 cm/hr, or between about 120 cm/hr and about 150 cm/hr. In some embodiments, the process flow rate is at least about 75 cm/hr, at least about 80 cm/hr, at least about 90 cm/hr, at least about 100 cm/hr, at least about 110 cm/hr, at least about 115 cm/hr, at least about 120 cm/hr, at least about 125 cm/hr, at least about 130 cm/hr, at least about 135 cm/hr, at least about 140 cm/hr, or at least about 150 cm/hr. In some embodiments, the process flow rate is about 125 cm/hr.
Embodiments of the invention include methods for recovering a selected recombinant polypeptide at a manufacturing scale; including a method wherein the selected recombinant polypeptide is a therapeutically useful or beneficial compound.
In some embodiments, the composition containing the initial population of recombinant polypeptides contains only the recombinant polypeptide of interest with differing levels of the selected characteristic. In some embodiments, the composition containing the initial population of recombinant polypeptides also contains additional polypeptides that have a different amino acid sequence than the recombinant polypeptide of interest. In some embodiments, the additional polypeptides are recombinant. In some embodiments, the composition containing the initial population of recombinant polypeptides also contains impurities. In some embodiments, the impurity is a DNA, RNA, lipid or protein molecule. In some embodiments, the impurity is a truncated form of the recombinant polypeptide, an aggregated form of the recombinant polypeptide, or a misfolded form of the recombinant polypeptide. In some embodiments, the composition containing the recombinant polypeptide that does not bind the CEX medium has less impurities that the composition that contained the initial population of recombinant polypeptides. In some embodiments, the composition containing the recombinant polypeptide that does not bind the CEX medium has at least about 5%, at least about 10%, at least about 25%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, or at least about 99% less impurities than the composition that contained the initial population of recombinant polypeptides.
In some embodiments, the recombinant polypeptides that do not bind the CEX medium are between about 10% and about 90%, between about 20% and about 80%, between about 30% and about 80%, between about 40% and about 80%, between about 50% and about 80%, or between about 55% and about 80% of the recombinant polypeptides of the composition comprising the initial population. In some embodiments, the recombinant polypeptides that do not bind the CEX medium are between about 55% and about 80% of the recombinant polypeptides of the composition comprising the initial population.
In one embodiment, product may be selectively enriched/separated, for example, based on peak product pI values wherein, for example, higher pI isoforms may be separated from lower pI product isoforms on a cation exchange adsorbent.
In some embodiments, the recombinant polypeptides that do not bind the CEX medium are subjected to one or more further purification steps following the CEX chromatography. In some embodiments, the composition containing the initial population of recombinant polypeptides is subjected to one or more purification steps prior to the contacting with the CEX medium. In some embodiments, the pH and the conductivity of the composition with the initial population of recombinant polypeptides are adjusted prior to contacting the composition with the CEX medium. In some embodiments the pH of the recombinant polypeptides that do not bind the CEX medium is adjusted following the contacting with the CEX medium.

Recombinant Polypeptides of the Invention

Embodiments of the invention are useful for obtaining highly homogeneous mixtures of a wide variety of recombinant polypeptides with specific levels of post-translational modifications. Some examples of such recombinant polypeptides include, without limitation, proteins and protein fragments (i.e., full-length and partial length polypeptides/peptides), antibodies (immunoglobulins), heterologous fusion proteins, etc. . . . . In some embodiments, the polypeptide is a dimer. In some embodiments, the polypeptide is a monomer.
In one embodiment, the recombinant polypeptide is a non-immunoglobulin proteins (or fragments thereof) fused with an immunoglobulin (or domains, regions, of fragments thereof). In some embodiments, the recombinant polypeptide comprises an Fc domain. In some embodiments, the recombinant polypeptide comprises an antibody. In one embodiment, for example, methods of the invention are used for separation/purification of a recombinant polypeptide comprising an extracellular receptor ligand-binding domain linked (i.e., “fused”) with the Fc-region of an immunoglobulin (such as the Fc region of an IgG molecule). Examples of Fc-fusion proteins can be seen in Table 1.

TABLE 1

Key Fc-fusion proteins and monoclonal antibodies (mAbs) in the clinic

Trade name		Indication of first
(generic name)	Description	FDA approval	Stage	Company

Fc-fusion

Nulojix	CTLA-4 fused to the Fc of	Organ rejection	FDA Approved	Bristol-Meyers
(belatacept)	human IgG1		(2011)	Squibb
Eylea	VEGFR1/VEGFR2 fused	Age related macular	FDA Approved	Regeneron
(aflibercept)	to the Fc of human IgG1	degeneration	(2011)	Pharmaceuticals
Arcalyst	IL-1R fused to the Fc of	Cryopyrin-associated	FDA Approved	Regeneron
(rilonacept)	human IgG1	periodic syndromes	(2008)	Pharmaceuticals
NPlate	Thrombopoietin-binding	Thrombocytopenia in	FDA Approved	Amgen/Pfizer
(romiplostim)	peptide fused to the Fc of	chronic immune	(2008)
	human IgG1	thrombocytopenic
		purpura patients
Orencia	Mutated CTLA-4 fused to	Rheumatoid arthritis	FDA Approved	Bristol-Meyers
(abatacept)	the Fc of human IgG1		(2005)	Squib
Amevive	LFA-3 fused to the Fc of	Psoriasis and	FDA Approved	Astellas Pharma
(alefacept)	human IgG1	transplant rejection	(2003)
Enbrel	TNFR fused to the Fc of	Rheumatoid arthritis	FDA Approved	Amgen/Pfizer
(etanercept)	human IgG1		(1998)

mAbs

Rituxan/MabThera	Chimeric mouse/human	B cell lymphomas	FDA Approved	Biogen
(rituximab)	IgG1 targeting CD20		(2006)	Idec/Genentech
				Hoffman-La
				Roche (Europe)
Herceptin	Chimeric mouse/human	Breast cancer and	FDA Approved	Genentech
(trastuzumab)	IgG1 targeting HER2	gastroesophageal	(2006)
		junction
		adenocarcinoma
Campath/Lemtrada	Humanized IgG1 targeting	B cell chronic	FDA Approved	Genzyme
(alemtuzumab)	CD52 on B and T	lymphocytic leukemia.	(2007)
	lymphocytes	In phase IIIa trials for
		multiple sclerosis
Prolia/Xgeva	Fully human IgG2	Osteoporosis	FDA Approved	Amgen
(denosumab)	targeting RANKL		(2010)
Tysabri	Humanized IgG4 tageting	Multiple sclerosis and	FDA Approved	Biogen Idec and
(natalizumab)	alpha-4 integrin	Crohn's disease	(2004)	Élan
Vectibix	Fully human IgG2	Metastatic colorectal	FDA Approved	Amgen
(panitumumab)	targeting EGFR, ErbB-1	cancer (in patients with	(2006)
	and HER1	non-mutated KRAS
Soliris	Humanized IgG2/4κ	Paroxysmal nocturnal	FDA Approved	Alexion
(eculizumab)	targeting complement	haemoglobinuria to	(2007)	Pharmaceuticals
	protein C5	reduce haemolysis
Erbitux	Chimeric mouse human	Metastatic colorectal	FDA Approved	Bristol-Myers
(cetuximab)	IgG1 targeting EGFR,	cancer (in patients with	(2006)	Squibb and Eli
	ErbB-1 and HER1	non-mutated KRAS		Lilly
Avastin	Humanized IgG1 targeting	Metastatic colorectal	FDA Approved	Genentech/Roche
(bevacizumab)	VEGF	cancer and HER2-	(2008)
		negative metastatic	Withdrawn
		breast cancer	(2011)
Remicade	Chimeric mouse human	Psoriasis, Crohn's	FDA Approved	Janssen
(infliximab)	IgG1 targeting TNF-α	disease, ankylosing	(1998)	Biotech/Schering-
		spondylitis,		Plough
		rheumatoid arthritis

In one embodiment, the recombinant polypeptide is an Fc fusion polypeptide comprising a ligand binding domain of a receptor. In some embodiments, the receptor is a Tumor necrosis factor (“TNF”) receptor. In some embodiments, the recombinant polypeptide is etanercept. Etanercept is a dimeric recombinant therapeutic glycoprotein, which consisting of the extracellular ligand binding portion of the human 75 kilodalton human tumor necrosis factor receptor linked to the constant region (Fc) of human IgG1. The TNF receptor region binds to soluble TNF-α found in the bloodstream, thereby reducing a variety of inflammatory responses, including many autoimmune diseases. Etanercept is as a TNF inhibitor, an acts as a decoy receptor that binds to TNF. Zalevsky, J. et al., J. Immunol. 179(3): 1872-83. Etanercept acts in a similar function to naturally occurring soluble TNF receptors. However, as etanercept is a fusion protein, it has a greater half-life in the bloodstream, and therefore has a longer impact than a naturally occurring receptor. Madhusudan, S. J. Clin Oncol. 23(25): 5950-9. The Fc portion of the fusion protein transiently anchors to Fc receptors expressed on the surface of endothelial cells, which delays the degradation and increases the half-life of etanercept.
Etanercept requires N-glycosylation for biological activity. Glycosylated proteins are complex molecules and even a well-controlled product may consist of several hundred or more glycoforms with different glycan compositions on the same amino acid sequence. The in vivo biological activity of glycosylated proteins is known to be dependent on the number of sialic acid units per molecule, which is a result of the available sialylation sites, the antenniarity of the N-glycans and the completeness of sialylation. Shiestl, M., et al. Nature Biotechnology 29(4):310 (2011).
In some embodiments, the recombinant polypeptide comprises a clotting factor. In some embodiments, the clotting factor is selected from Factor VII (FVII), FVIIa, Factor VIII (FVIII), Factor IX (FIX), or FIXa (FIX). In some embodiments, the FVIII is full-length FVIII or B-domain deleted FVIII. In some embodiments, the FVIII is single chain FVIII or dual chain FVIII.
In some embodiments, the recombinant polypeptide is a monomer-dimer hybrid. A monomer-dimer hybrid is a chimeric protein having a dimeric aspect and a monomeric aspect, wherein the dimeric aspect relates to the fact that it is comprised of two polypeptide chains each comprised of a portion of an immunoglobulin constant region, and wherein the monomeric aspect relates to the fact that only one of the two chains is comprised of a therapeutic biologically active molecule. Monomer-dimer hybrids are described in detail is U.S. Pat. No. 7,404,956, which is incorporated herein by reference in its entirety.
“Factor VII” or “FVII” refers to a coagulation factor protein synthesized in the liver and secreted into the blood as a single chain zymogen with a molecular weight of approximately 50 kDa. The FVII zymogen is converted into an activated form (FVIIa) by proteolytic cleavage. FVII is disclosed in U.S. Publ. No. 2011/0046061 and Int'l Publ. No. PCT/US2013/44842, each of which is incorporated herein by reference in its entirety.
“Factor VIII” or “FVIII” refers to a blood coagulation factor protein and species and sequence variants thereof that includes, but is not limited to, the 2351 amino acid single-chain precursor protein (with a 19-amino acid hydrophobic signal peptide), the mature 2332 amino acid factor VIII protein of approximately 270-330 kDa with the domain structure A1-A2-B-A3-C1-C2, as well as the circulating heterodimer of two chains that form as a result of proteolytic cleavage after R1648 of a heavy chain form composed of A1-A2-B (in the range of 90-220 kD) of amino acids 1-1648 (numbered relative to the mature FVIII form) and a light chain A3-C1-C2 of 80 kDa of amino acids 1649-2232, each of which is depicted schematically in FIG. 1. “Factor VIII” or “FVIII” also can be sequence variants that retain at least a portion of the biological activity of the native circulating protein, including truncated sequences, a sequence that includes heterologous amino acids, or a single chain FVIII (scFVIII) in which the heavy and light chains are covalently connected by a linker. As used herein, “FVIII” shall be any functional form of factor VIII molecule with the typical characteristics of blood coagulation factor VIII capable of in vivo or in vitro correction of human factor VIII deficiencies (e.g., hemophilia A). FVIII or sequence variants have been isolated, characterized, and cloned, as described in U.S. Pat. or Publ. Nos. U.S. Pat. Nos. 4,757,006; 7,138,505; 5,004,804; 5,198,349, 5,250,421; 5,919,766; 2010/0081615; 2013/0017997 and 2013/0108629 each of which is incorporated herein by reference in its entirety.
“B domain” of Factor VIII, as used herein, is the same as the B domain known in the art that is defined by internal amino acid sequence identity and sites of proteolytic cleavage by thrombin, e.g., residues Ser741-Arg1648 of full length human factor VIII. The other human factor VIII domains are defined by the following amino acid residues: A1, residues Ala1-Arg372; A2, residues Ser373-Arg740; A3, residues Ser1690-Ile2032; C1, residues Arg2033-Asn2172; C2, residues Ser2173-Tyr2332. The A3-C1-C2 sequence includes residues Ser1690-Tyr2332. The remaining sequence, residues Glu1649-Arg1689, is usually referred to as the factor VIII light chain activation peptide. The locations of the boundaries for all of the domains, including the B domains, for porcine, mouse and canine factor VIII are also known in the art. Preferably, the B domain of Factor VIII is deleted (“B domain deleted factor VIII” or “BDD FVIII”). An example of a BDD FVIII is REFACTO (recombinant BDD FVIII). The B domain of FVIII is discussed in U.S. Publ. No. 2013/0108629, which is incorporated herein by reference in its entirety.
A “B domain deleted factor VIII” may have the full or partial deletions disclosed in U.S. Pat. Nos. 6,316,226, 6,346,513, 7,041,635, 5,789,203, 6,060,447, 5,595,886, 6,228,620, 5,972,885, 6,048,720, 5,543,502, 5,610,278, 5,171,844, 5,112,950, 4,868,112, and 6,458,563, each of which is incorporated herein by reference in its entirety. In some embodiments, a B domain deleted factor VIII sequence of the present invention comprises any one of the deletions disclosed at col. 4, line 4 to col. 5, line 28 and examples 1-5 of U.S. Pat. No. 6,316,226 (also in U.S. Pat. No. 6,346,513). In some embodiments, a B domain deleted factor VIII of the present invention has a deletion disclosed at col. 2, lines 26-51 and examples 5-8 of U.S. Pat. No. 5,789,203 (also U.S. Pat. No. 6,060,447, U.S. Pat. No. 5,595,886, and U.S. Pat. No. 6,228,620). In some embodiments, a B domain deleted factor VIII has a deletion described in col. 1, lines 25 to col. 2, line 40 of U.S. Pat. No. 5,972,885; col. 6, lines 1-22 and example 1 of U.S. Pat. No. 6,048,720; col. 2, lines 17-46 of U.S. Pat. No. 5,543,502; col. 4, line 22 to col. 5, line 36 of U.S. Pat. No. 5,171,844; col. 2, lines 55-68, FIG. 2, and example 1 of U.S. Pat. No. 5,112,950; col. 2, line 2 to col. 19, line 21 and table 2 of U.S. Pat. No. 4,868,112; col. 2, line 1 to col. 3, line 19, col. 3, line 40 to col. 4, line 67, col. 7, line 43 to col. 8, line 26, and col. 11, line 5 to col. 13, line 39 of U.S. Pat. No. 7,041,635; or col. 4, lines 25-53, of U.S. Pat. No. 6,458,563. In some embodiments, a B domain deleted factor VIII has a deletion of most of the B domain, but still contains amino-terminal sequences of the B domain that are essential for in vivo proteolytic processing of the primary translation product into two polypeptide chain, as disclosed in WO 91/09122, which is incorporated herein by reference in its entirety. In some embodiments, a B domain deleted factor VIII is constructed with a deletion of amino acids 747-1638, i.e., virtually a complete deletion of the B domain. Hoeben R. C., et al, J. Biol. Chem. 265 (13): 7318-7323 (1990), incorporated herein by reference in its entirety. A. B domain deleted factor VIII may also contain a deletion of amino acids 771-1666 or amino acids 868-1562 of factor VIII. Meulien P., et al. Protein Eng. 2(4): 301-6 (1988), incorporated herein by reference in its entirety. Additional B domain deletions that are part of the invention include, e.g.: deletion of amino acids 982 through 1562 or 760 through 1639 (Toole et al., Proc. Natl. Acad. Sci. U.S.A. (1986) 83, 5939-5942)), 797 through 1562 (Eaton, et al. Biochemistry (1986) 25:8343-8347)), 741 through 1646 (Kaufman (PCT published application No. WO 87/04187)), 747-1560 (Sarver, et al., DNA (1987) 6:553-564)), 741 through 1648 (Pasek (PCT application No. 88/00831)), 816 through 1598 or 741 through 1689 (Lagner (Behring Inst. Mitt. (1988) No 82:16-25, EP 295597)), each of which is incorporated herein by reference in its entirety. Each of the foregoing deletions may be made in any Factor VIII sequence. B domain deletions of FVIII are disclosed in U.S. Publ. No. 2013/0108629, which is incorporated herein by reference in its entirety.
“Factor IX” and “FIX,” as used herein, means functional Factor IX polypeptide in its normal role in coagulation, unless otherwise specified. Thus, the term Factor IX includes variant polypeptides that are functional and the polynucleotides that encode such functional variant polypeptides. Preferred Factor IX polypeptides are the human, bovine, porcine, canine, feline, and murine Factor IX polypeptides. The full length polypeptide and polynucleotide sequences of Factor IX are known, as are many functional variants, e.g., fragments, mutants and modified versions. Factor IX polypeptides include full-length Factor IX, full-length Factor IX minus Met at the N-terminus, full-length Factor IX minus the signal sequence, mature Factor IX (minus the signal sequence and propeptide), and mature Factor IX with an additional Met at the N-terminus. Factor IX is preferably made by recombinant means (“recombinant Factor IX” or “rFIX”), i.e., it is not naturally occurring or derived from plasma. FIX is disclosed in U.S. Publ. Nos. 2011/0046060 and 2013/0202595, each of which is incorporated herein by reference in its entirety.
In some embodiments, the recombinant polypeptide is an antibody. In some embodiments, the recombinant polypeptide is a monoclonal antibody. In some embodiments, the antibody is a humanized antibody. In some embodiments, the recombinant polypeptide is a chimeric antibody. In some embodiments, the recombinant polypeptide is any antibody disclosed in U.S. Pat. No. 7,300,773, which is incorporated herein by reference in its entirety.
In some embodiments, the recombinant polypeptide is a receptor. In some embodiments, the antibody is a receptor tyrosine kinase. In some embodiments, the receptor is any receptor disclosed in U.S. Pat. No. 7,300,773, which is incorporated herein by reference in its entirety.
In some embodiments the recombinant polypeptide is a growth factor or other signaling molecule. In some embodiments the recombinant polypeptide is a G-protein coupled receptor. In some embodiments the recombinant polypeptide is any polypeptide disclosed in U.S. Pat. No. 7,300,773.
In some embodiments, the recombinant polypeptide is produced by a host cell. In some embodiments, the recombinant polypeptide is produced by a eukaryotic host cell. In some embodiments, the recombinant polypeptide is produced by a mammalian host cell.

ABBREVIATIONS

AEX: anion exchange chromatography
CEX: cation exchange chromatography
CV: column volume
DF: diafiltration
DoE: design of experiments
HIC: hydrophobic interaction chromatography
HMW: high molecular weight aggregates
LMW: low molecular weight aggregates
HCP: host cell protein
Peak 1: clipped etanercept
Peak 2: native etanercept
Peak 3: misfolded etanercept
LRV: Log₁₀(total impurity in load/total impurity in eluate)
CV: column volume
PS: pilot scale
OD: optical density
TSA: total sialic acid
UF: ultrafiltration
WFI: water for injection
By applying knowledge within the skill of those in the art, embodiments of the invention may be modified and/or adapted for various applications, without undue experimentation, without departing from the general concept of the present invention. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein.

EXAMPLES

Example 1

Enrichment of TSA and Removal of Impurities Through Use of a SE Hicap Column

Summary

A chromatography process was developed for the isolation/purification/enrichment of recombinant polypeptides with enhanced or increased levels of sialylation compared to recombinant polypeptides with decreased or lower levels of sialylation present in the same initial mixture.
The recombinant polypeptide utilized in this example is the TNFR-Fc fusion protein etanercept. Highly sialylated forms of recombinant polypeptides can represent a highly desirable class of therapeutically advantageous protein isoforms. The present example describes development of a robust process capable of enriching the content of recovered/isolated, highly sialylated forms of recombinant polypeptides while maintaining acceptable product recovery and yield. In this particular example, a process was developed wherein SE Hicap chromatography was used to recover/isolate highly sialylated forms of an Fc-fusion protein.
SE Hicap utilized in flow-through mode was selected primarily for its TSA enrichment potential, ability to reduce Peak 3 and aggregates, capability for robust DNA clearance, and ease of interface with the other process steps. SE Hicap enriches TSA by electrostatically repelling the negatively-charged sialylated etanercept into the flow-through, while retaining the more positively-charged (lesser sialylated) protein when run at a pH below its pI. It was found that load pH, load conductivity, and loading ratio are all key and critical parameters for this column. Process temperature, process flow rate, and resin ligand capacity had negligible impact on yield and product attributes under the conditions studied and were judged to be non-key process parameters.

Materials

Solutions: The pH and conductivity of each buffer were verified before use.
Load Material and Adsorbent: All samples were frozen at −70° C. and thawed at ambient temperature prior to initiating chromatography. For all of the experiments, the load pH was adjusted with 1 M acetic acid, 1 M citric acid, or 2.4 M Tris base. Then, the load conductivity was adjusted with 1 M NaCl in acetate or citrate buffer. RO/DI water was added if the load conductivity was too high.

Chromatography Method

All columns were packed with a 20% compression factor to a packed bed height of 15 cm or 16 cm. The chromatography steps were carried out with an AKTA Explorer 900 (GE Healthcare Life Sciences) and the Unicorn interface software (version 5.11) at approximately 22° C. in a down-flow mode. Throughout all of the development studies operated in flow-through mode, the chromatography method generally consisted of an equilibration step, a load step, a wash step to remove non-bound protein, a strip step to remove impurities for analysis, a cleaning step with 1 N NaOH, and a storage step in 0.1 N NaOH. The cleaning and storage conditions for this step were not studied; rather these follow the manufacturer's recommendations. The wash fractions were pooled with the flow-through fractions unless otherwise noted. The flow-through, wash, and strip fractions were analyzed for yield and product attributes.

Resin Screening, Column Interfacing, and Buffer Matrix Method

Static binding capacity calculations were used to screen candidate CEX resins for their ability to bind protein. This was determined by buffer exchanging the candidate resins with equilibration buffer and then incubating the composition containing the Etanercept overnight with a known volume of candidate resins on a shaker. The mixtures of resin and protein were spun down and the supernatants were subsequently measured for A280. The resins with high static capacities were then packed in columns and further evaluated in bind/elute or flow-through mode. Product yield, aggregates, Peak 1, Peak 2, Peak 3, TSA, HCP, and DNA were measured to gauge separation performance. Resins with high capacities that had poor separation of product-related impurities during elution were further evaluated as a capture step, but eliminated as a polishing step. However, resins with low capacities that had good separation of impurities were further evaluated in flow-through mode, as was the case with SE Hicap.
SE Hicap was selected specifically for its ability to enrich TSA and remove aggregates, DNA, and some Peak 3 and HCP. In addition, SE Hicap in flow-through mode had no challenges interfacing with previous and subsequent purification steps, while eliminating need for any intermediate step. It was determined that acetate buffer was the most optimal buffer to be used in this process.

DOE Method

A DoE (central composite) study was designed to characterize the load ratio, load conductivity, and load pH, while a second DoE (screening) was designed to characterize the process temperature, resin capacity, and process flow rate. Both DoE studies were designed using Design Expert (version 8.0.6). Load ratio, load conductivity, and load pH were chosen as variables in the first DoE because earlier experiments showed that they had an impact on product yield and product attributes. Process temperature, resin capacity, and process flow rate were assessed in a separate DoE because earlier studies showed that these parameters had minimal effect on product yield and product attributes.
To perform regression analyses on the data, the results were entered into the Design Expert and analyzed first for normal distribution and outliers via Box Cox and Externally Studentized Residuals, respectively. If the data was not normally distributed, transformations were conducted (e.g., log 10) based on the software's recommendations. Any outliers that significantly weakened the models were omitted from the analysis. Afterwards, insignificant parameters (p-value >0.05) were removed using the backwards or manual elimination function to simplify the model. In a few cases, insignificant parameters were retained in the model to strengthen the R2 and lack of fit. All models were built on the assumption that only main effects and 2-level interactions would be significant and not be confounded.

Analytical Methods

The analytical methods utilized for all of the experiments are summarized in Table 2. The starting material is sufficiently pure that measurement of the product yield using OD280 method is accurate for the SE Hicap column.

TABLE 2

Summary of Analytical Methods

			Method Validation/
			Qualification Report
Analytical Method	Measurement	Unit	Number(s)

OD₂₈₀	Total absorbance in each fraction	Non-dimensional	Not Applicable
	and total A₂₈₀in the eluate
Pressure	Column inlet pressure	Psig	AKTA program
UV₂₈₀	Chromatograph	n/a	Not Applicable
HPLC-SEC	Non-reversible soluble aggregate	%	TD-TDMP-9032
HPLC-HIC	Peak	1, Peak 2, and Peak 3	%	TD-TDMP-242
LC-90/GXII (Non-	Purity and Highest Single Impurity	%	TD-TDMP-285
Reduced)
LC-90/GXII	Purity and LMW	%	TD-TDMP-286
(Reduced)
HPLC-IEX	Total Sialic Acid (TSA)	Mole per mole	TD-TDMP-370
iCIEF	Charged Heterogeneity	%	TD-TDMP-284
ECL	Total Host Cell Protein	Parts per million	TD-TDMP-252
		(ppm)
Q-PCR	Total DNA	Parts per billion	TD-TDMP-321
		(ppb)

DOE 1 (Central Composite)

The DoE study characterizing load ratio, load pH, and load conductivity was successfully completed without any deviations from the study design. A typical SE Hicap chromatogram under control conditions shows how the UV deflects with a pre-peak during the load, decreases in UV, and then increases in UV before reaching a plateau (FIG. 1). It was found that weak protein-binding can lead to insufficient TSA enrichment (data not shown). It was found that strong protein-binding can lead to product loss (data not shown).
Low load pH and low load conductivity decreased product yield, enriched TSA content, increased Peak 1 impurity, decreased aggregate level, and increased monomer content (Table 3, see also Table 4). Load pH and load conductivity have an interaction in that a low load pH can offset the effects of high load conductivity on these outputs and vice versa. As load conductivity or load pH increased, Peak 2 level decreased by the amount that was increased in Peak 3 level (Table 3, see also Table 4). This showed that varying load conductivity and load pH can change the relative distribution of Peaks 1, 2, and 3.

TABLE 3

DOE 1 (Central Composite) Data #1

Load

Ratio

Load

Azso

HMW

Reduced

(OD/mL

Conductivity

Load

Yield

Aggregate

Monomer

Peak 1

Peak2

Peak3

NANA

NGNA

TSA

Purity

Cycle

resin)

(mS/cm)

pH

(%)

(mol/mol)

(%)

1	40.9	9.0	5.8	66.9	3.4	96.7	4.9	60.0	34.3	15.5	0.0	15.6	95.1
2	54.6	9.0	5.8	71.1	4.0	96.0	4.7	60.1	34.2	15.4	0.1	15.5	94.9
3	27.1	9.0	5.8	58.1	2.8	97.2	4.5	63.2	31.4	15.8	0.1	15.9	94.3
4	49.0	11.0	6.3	87.9	8.7	91.3	4.0	53.5	41.5	14.5	0.1	14.6	95.2
5	32.7	11.0	6.3	83.9	8.4	91.6	4.5	54.1	40.4	14.7	0.1	14.8	95.3
6	49.0	11.0	5.3	65.0	2.4	97.6	4.8	63.8	30.1	15.9	0.1	16.0	94.2
7	32.7	11.0	5.3	58.5	1.8	98.2	4.6	64.5	30.3	15.9	0.1	16.0	94.0
8	40.9	9.0	5.8	63.3	3.6	96.4	4.5	60.9	33.5	15.3	0.1	15.4	94.8
9	40.9	9.0	5.8	62.9	3.4	96.6	4.5	61.7	33.0	16.0	0.1	16.1	94.9
10	40.9	12.4	5.8	78.1	7.7	92.3	4.1	55.7	39.3	14.5	0.1	14.6	95.5
11	40.9	5.6	5.8	45.1	2.1	97.9	5.4	66.1	27.8	16.7	0.1	16.8	94.4
12	32.7	7.0	6.3	63.5	5.8	94.2	5.0	59.7	33.9	16.1	0.1	16.3	94.9
13	49.0	7.0	6.3	67.0	4.4	95.6	4.3	58.3	36.4	15.5	0.1	15.6	95.2
14	49.0	7.0	5.3	28.5	1.8	98.2	7.4	70.5	20.5	17.7	0.1	17.8	92.3
15	32.7	7.0	5.3	13.7	0.0	100.0	12.9	67.3	16.5	18.5	0.1	18.6	86.3
16	40.9	9.0	5.0	21.5	0.0	100.0	9.9	70.8	17.0	18.2	0.1	18.3	89.7
17	40.9	9.0	6.6	82.9	8.2	91.8	4.5	54.5	39.9	14.8	0.1	14.9	95.2
18	40.9	9.0	5.8	67.6	3.6	96.4	4.0	62.9	32.5	15.9	0.1	16.1	95.1

TABLE 4

Effect of Load Ratio, Load pH and Load Conductivity on Yield,
TSA, Aggregation, and Peak Size.

	Load		Load
Feed	Ratio	Load	Conductivity	A280	TSA	Aggregate	Peak	Peak	Peak
Source	(mg/mL)	pH	(mS/cm)	Yield (%)	(mole/mole)	(%)	1 (%)	2 (%)	3 (%)

C12-01	53	5.6	10	73.5	15.7	5.1	6.9	61	32.1
C12-01	28	5.6	10	64.9	15.4	3.7	6.1	63.7	30.1
C12-01	56	5.6	10	74.6	15.7	5.1	6.2	60.6	33.2
ILS-003	53	5.8	11	78.5	15.4	8.1	5.8	63.1	31
ILS-003	56	5.8	11	78.3	15.6	8.1	6	62.9	31.2
ILS-003	53	5.6	10	70.2	16	4.5	6.5	66.6	27
ILS-003	56	5.6	10	70.4	16.5	4.7	6.4	66.3	27.3

TABLE 5

DOE 1 (Central Composite) Data #2

Load

Non-

Ratio

Load

Non-

Reduced

HCP

DNA

Acidic

Basic

Main

(OD/mL

Conductivity

Load

Reduced

Impurity

Content

Clearance

Content

Clearance

Isoform

Cycle

resin)

(mS/cm)

pH

LMW (%)

Purity (%)

(%)

(ppm)

(LRV)

(ppb)

(LRV)

(%)

1	40.9	9.0	5.8	2.6	96.2	3.8	1581	0.3	58.4	1.5	57.7	5.3	37.1
2	54.6	9.0	5.8	2.6	96.5	3.5	1590	0.3	39.6	1.7	58.7	5.4	36.0
3	27.1	9.0	5.8	3.2	96.7	3.3	1721	0.3	44.4	1.7	60.4	4.7	34.8
4	49.0	11.0	6.3	2.4	96.7	3.3	1416	0.2	190.5	0.9	60.4	5.1	34.5
5	32.7	11.0	6.3	2.3	96.4	3.6	1327	0.3	175.2	0.9	59.9	4.7	35.4
6	49.0	11.0	5.3	3.1	96.4	3.6	1446	0.3	40.0	1.7	56.6	6.9	36.5
7	32.7	11.0	5.3	3.4	96.5	3.5	1516	0.4	24.4	2.0	56.1	6.2	37.7
8	40.9	9.0	5.8	2.8	96.6	3.4	1719	0.3	42.7	1.7	58.7	6.0	35.4
9	40.9	9.0	5.8	2.8	96.6	3.4	1698	0.3	54.2	1.6	58.6	5.0	36.4
10	40.9	12.4	5.8	2.2	97.1	2.9	1561	0.2	64.6	1.4	57.2	6.2	36.6
11	40.9	5.6	5.8	3.7	96.7	3.3	2448	0.3	35.6	1.9	61.4	4.2	34.4
12	32.7	7.0	6.3	2.9	96.6	3.4	1834	0.3	86.0	1.4	59.2	5.2	35.7
13	49.0	7.0	6.3	2.7	91.5	8.5	1564	0.3	98.1	1.3	58.0	4.5	37.5
14	49.0	7.0	5.3	5.5	81.8	18.2	3024	0.4	11.7	2.6	63.4	4.4	32.2
15	32.7	7.0	5.3	11.0	88.4	11.6	6435	0.4	42.4	2.4	75.0	3.8	21.2
16	40.9	9.0	5.0	6.8	84.6	15.4	3644	0.4	21.3	2.5	66.5	5.0	28.5
17	40.9	9.0	6.6	2.2	96.8	3.2	1149	0.3	204.8	0.9	60.1	4.2	35.7
18	40.9	9.0	5.8	2.6	97.0	3.0	1387	0.3	39.1	1.7	57.0	5.2	37.8

A high load conductivity or high load pH decreased DNA clearance (Table 5). However, load pH decreased DNA clearance to a greater extent than conductivity. Also, a high load pH also decreased HCP clearance (Table 5).
Low load pH and low load conductivity decreased purity level (relative to all impurities) (Table 5). Load pH and load conductivity have an interaction in that a low load pH can offset the effects of high load conductivity on the purity level. As load conductivity or load pH increased, the highest single impurity level and LMW decreased (Table 5).
The negatively-charged acidic isoform was enriched at low conductivity and low pH, but reduced in concentration when the basic and main isoforms desorbed from the column at high conductivity or high pH (Table 5). Therefore, load pH and load conductivity have an interaction in that load pH can offset the effects of load conductivity on the isoforms.
These experiments indicate that the operating space for SE Hicap should have a load pH target of 5.6 with a range of 5.5-5.8, a load conductivity target of 10.0 mS/cm with a range of 9.5-11 mS/cm, and a load ratio target of 41 mg/mL resin with a range of 33-54 mg/mL resin. These load conditions would ensure that the flow-through/wash pool have TSA levels of 15-16.5 mole/mole, aggregate levels of <6%, Peak 1 levels of <6%, DNA clearance of ˜1.5 LRV, and a sufficient product yield of 55-80%.

DoE 2 (Screening)

The DoE study characterizing process temperature, resin capacity, and process flow rate was successfully completed without any deviations from the protocol. The data from this DoE study are listed in Table 6. Although the most significant variables were resin capacity and process temperature, their impact on the product yield and product attributes were negligible. Thus, the process is robust and can tolerate a wide operating range for temperature, resin capacity, and flow rate.

TABLE 6

DOE 2 (Screening) Data.

	Process	Resin Capacity	Process			HMW
	Temperature	(mg Lysozyme/	Flow Rate	A₂₈₀Yield	TSA	Aggregate	Monomer	Peak	1	Peak 2	Peak 3
Cycle	(° C.)	mL resin)	(cm/hr)	(%)	(mol/mol)	(%)	(%)	(%)	(%)	(%)

1	26.0	125	75	76.8	14.6	4.6	95.4	4.2	63.8	32.0
2	26.0	158	150	74.4	14.5	4.9	95.1	4.5	62.4	33.1
3	26.0	125	150	73.6	14.0	4.6	95.4	4.6	63.1	32.3
4	26.0	158	75	72.9	14.5	4.7	95.3	4.5	62.6	32.9
5	16.0	125	150	69.1	14.4	4.1	95.9	4.2	64.7	31.1
6	16.0	158	75	71.0	14.8	4.2	95.8	4.3	64.3	31.4
7	16.0	158	150	70.0	14.7	4.3	95.7	4.3	64.4	31.3
8	16.0	125	75	68.7	14.4	4.1	95.9	4.5	65.0	30.5
9	21.0	142	113	72.4	14.7	4.3	95.7	4.9	64.2	30.9
10	21.0	142	113	71.5	14.7	4.3	95.7	4.9	64.2	30.9
11	21.0	142	113	72.4	13.6	4.4	95.6	4.9	64.6	30.5
12	21.0	142	113	71.5	14.5	4.3	95.7	5.1	64.1	30.8

Conclusions

The SE Hicap flow-through chromatography was successfully developed as the second purification step to enrich TSA levels to 15-16.5 mole/mole, decrease aggregates by ˜12%, and reduce DNA by ˜1.5 LRV, while maintaining high product recoveries of 55-75% (A280) under target operating conditions. To meet these key and critical product attributes, the recommended operating space for SE Hicap would have a load pH target of 5.6±0.2, a load conductivity target of 10.0 mS/cm with a range of 9.5-11 mS/cm, and a load ratio target of 41 mg/mL resin±8 mg/mL resin based on DoE results. Other process parameters such as process temperature, process flow rate, and resin capacity had negligible impact on product yield and product attributes.

Example 2

Enrichment of TSA Using CEX Resin

Having determined the enrichment parameters for the SE Hicap CEX resin, the operating conditions necessary to enrich TSA while removing aggregates and/or misfolds was determined for other CEX resins. The resins tested were: GE SPXL, GE SP Sepharose, Millipore Eshmuno S, Tosoh Gigacap CM, Tosoh Gigacap S-650, and BioRad Nuvia S. The final operating conditions for each column can be seen below in Table 7:

TABLE 7

Operating Conditions for CEX Columns.

				TSA		Misfolds
		Conductivity		Enriched	Aggregate	Removed
Columns	pH	(mS/cm)	Yield (%)	(mole/mole)	Removed (%)	(%)

SE Hicap	5.6	10	47.9	3.1	21.2	15.8
Control
SP Sepharose	5	9	44.0	2.3	9.5	26.8
SP Sepharose	5	6	53.3	2.2	7.3	16.0
XL
Nuvia S	5	9	47.6	3.8	17.6	12.7
Eshmuno S	5	9	55.0	2.5	16.7	13.7
GigaCap S	5	8	46.9	3.9	20.3	13.7
GigaCap CM	5	6	40.1	4.0	22.5	20.7

A comparison of the enrichment of TSA by each column, with the results normalized to 50% of product yield, can be seen in FIG. 2. A comparison of the aggregates and misfolds removed by each column, with the results normalized to 50% of product yield, can be seen in FIG. 3.
The present invention is not to be limited in scope by the specific embodiments described which are intended as single illustrations of individual aspects of the invention, and any compositions or methods which are functionally equivalent are within the scope of this invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description and accompanying drawings. Such modifications are intended to fall within the scope of the appended claims.
All documents, articles, publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.

Claims

What is claimed is:

1. A method for enriching the level of post-translational modification of recombinant polypeptides, comprising:

contacting a composition which comprises an initial population of recombinant polypeptides having different levels of post-translational modification with a cation exchange chromatography (CEX) medium operated in a flow-through mode;

wherein recombinant polypeptides that do not bind the CEX medium are separated from recombinant polypeptides that bind the CEX medium, and wherein the recombinant polypeptides that do not bind the CEX medium comprise a higher level of post-translational modification compared to the bound recombinant polypeptides.

2. A method for enriching the level of post-translational modification of recombinant polypeptides, comprising:

a) contacting a composition which comprises an initial population of recombinant polypeptides having different levels of post-translational modification with a cation exchange chromatography (CEX) medium operated in a flow-through mode; and

b) separating recombinant polypeptides that do not bind the CEX medium from recombinant polypeptides that bind the CEX medium;

wherein the recombinant polypeptides that do not bind the CEX medium that are recovered comprise a higher level of post-translational modification compared to the bound recombinant polypeptides.

3. A method for enriching the level of post-translational modification of recombinant polypeptides, comprising:

a) contacting a composition which comprises an initial population of recombinant polypeptides having different levels of post-translational modification with a cation exchange chromatography (CEX) medium operated in a flow-through mode;

b) separating recombinant polypeptides that do not bind the CEX medium from recombinant polypeptides that bind the CEX medium; and

c) recovering the recombinant polypeptides that do not bind the CEX medium;

wherein the recombinant polypeptides that do not bind the CEX medium comprise a higher level of post-translational modification compared to the bound recombinant polypeptides.

4. A method for enriching the level of post-translational modification of recombinant polypeptides, comprising:

a) providing a composition which comprises an initial population of recombinant polypeptides having different levels of post-translational modification;

b) contacting the composition with a cation exchange chromatography (CEX) medium operated in a flow-through mode;

c) separating recombinant polypeptides that do not bind the CEX medium from recombinant polypeptides that bind the CEX medium; and

d) recovering the recombinant polypeptides that do not bind the CEX medium;

5. The method of claim 1 or 2, further comprising recovering the recombinant polypeptides that do not bind the CEX medium.

6. The method of any one of claims 1-5, wherein the post-translational modification is sialylation or gamma-carboxyglutamate (Gla) formation.

7. The method of claim 6, wherein the post-translational modification is sialylation.

8. The method of claim 7, wherein the total sialic acid content of the recombinant polypeptides that do not bind the CEX medium is between about 0.5 and about 6 moles of sialic acid per mole of protein higher than that of the initial population of recombinant polypeptides.

9. The method of claim 8, wherein the total sialic acid content of the recombinant polypeptides that do not bind the CEX medium is between about 0.5 and about 4 moles of sialic acid per mole of protein higher than that of the initial population of recombinant polypeptides.

10. The method of claim 7, wherein the total sialic acid content of the recombinant polypeptides that do not bind the CEX medium is between about 5% and about 100% higher than that of the initial population of recombinant polypeptides.

11. The method of claim 10, wherein the total sialic acid content of the recombinant polypeptides that do not bind the CEX medium is between about 5% and about 40% higher than that of the initial population of recombinant polypeptides.

12. The method of any one of claims 7-11, wherein the total sialic acid content of the recombinant polypeptides that do not bind the CEX medium is between about 12 and about 20 moles of sialic acid per mole of protein.

13. The method of claim 12, wherein the total sialic acid content of the recombinant polypeptides that do not bind the CEX medium is between about 14 and about 17 moles of sialic acid per mole of protein.

14. The method of any one of claims 7-10, wherein the total sialic acid content of the initial population of recombinant polypeptides is about 10 to about 14 moles of sialic acid per mole of protein.

15. The method of claim 14, wherein the total sialic acid content of the initial population of recombinant polypeptides is about 13-14 moles of sialic acid per mole of protein.

16. The method of any one of claims 1-15, wherein the recombinant polypeptide comprises an Fc domain.

17. The method of claim 16, wherein the recombinant polypeptide comprises an antibody.

18. The method of claim 16, wherein the recombinant polypeptide comprises an Fc fusion polypeptide comprising a ligand binding domain of a receptor.

19. The method of claim 18, wherein the receptor is a TNF receptor.

20. The method of claim 19, wherein the recombinant polypeptide is etanercept.

21. The method of any one of claims 1-18, wherein the recombinant polypeptide comprises a clotting factor.

22. The method of claim 21, wherein the recombinant polypeptide is a monomer-dimer hybrid.

23. The method of claim 21 or 22, wherein the clotting factor is selected from Factor VII (FVII), FVIIa, Factor VIII (FVIII), Factor IX (FIX), or FIXa (FIX).

24. The method of claim 23, wherein the FVIII is full-length FVIII or B-domain deleted FVIII.

25. The method of claim 23 or 24, wherein the FVIII is single chain FVIII or dual chain FVIII.

26. The method of any one of claims 1-25, wherein the contacting occurs at a load ratio between about 30 and about 100 mg total protein/ml CEX medium.

27. The method of claim 26, wherein the contacting occurs at a load ratio between about 33 and about 54 mg total protein/ml CEX medium.

28. The method of claim 27, wherein the contacting occurs at a load ratio of at least about 41 mg total protein/ml CEX medium.

29. The method of any one of claims 1-28, wherein the contacting occurs at a pH between about 4 and about 7.

30. The method of claim 29, wherein the contacting occurs at a pH between about 5 and about 6.

31. The method of claim 30, wherein the contacting occurs at a pH between about 5.5 and about 5.8

32. The method of claim 30, wherein contacting occurs at a pH of at least about 5.6.

33. The method of any one of claims 1-32, wherein the contacting occurs at a conductivity between about 8 and about 12 mS/cm.

34. The method of claim 33, wherein the contacting occurs at a conductivity of between about 9.5 and about 11 mS/cm.

35. The method of claim 34, wherein the contacting occurs at a conductivity of at least about 10 mS/cm.

36. The method of any one of claims 1-35, wherein the recombinant polypeptides that do not bind the CEX medium comprise about 25% to about 80% of the initial population of recombinant polypeptides.

37. The method of claim 36, wherein the recombinant polypeptides that do not bind the CEX medium comprise about 55% to about 80% of the initial population of recombinant polypeptides.

38. The method of any one of claims 1-37, wherein the CEX medium comprises a ligand selected from the group consisting of sulfoethyl; sulphopropyl; sulfopropyl; CH₂—SO₃ ⁻; CH₂CH₂CH₂SO₃ ⁻; SO₃ ⁻; and CH₂—COO⁻¹.

39. The method of claim 38, wherein the CEX medium comprises a sulfoethyl ligand.

40. The method of claim 39, wherein the CEX medium comprises a binding capacity of between about 120 and about 160 mg lysozyme/ml resin.

41. The method of any one of claims 1-40, wherein the recombinant polypeptide is produced by a eukaryotic host cell.

42. The method of claim 41, wherein the eukaryotic host cell is a mammalian host cell.

43. The method of any one of claims 1-42, wherein the contacting is performed at a manufacturing scale.

44. The method of any one of claims 1-43, wherein the composition further comprises at least one impurity.

45. The method of claim 44, wherein the impurity comprises a DNA, RNA, lipid or protein.

46. The method of claim 45, wherein the impurity comprises a protein.

47. The method of claim 46, wherein the protein impurity comprises a truncated form of the recombinant polypeptide, an aggregated form of the recombinant polypeptide, or a misfolded form of the recombinant polypeptide.

48. The method of any one of claims 44-47, providing a final composition comprising the recombinant polypeptides that do not bind the CEX medium, wherein the final composition comprises less impurities than the composition that comprised the initial population of polypeptides.