WO2013109302A2 - Chromatography matrices including novel staphylococcus aureus protein a based ligands - Google Patents

Chromatography matrices including novel staphylococcus aureus protein a based ligands Download PDF

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Publication number
WO2013109302A2
WO2013109302A2 PCT/US2012/041070 US2012041070W WO2013109302A2 WO 2013109302 A2 WO2013109302 A2 WO 2013109302A2 US 2012041070 W US2012041070 W US 2012041070W WO 2013109302 A2 WO2013109302 A2 WO 2013109302A2
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Prior art keywords
domain
ligand
domains
deletion
spa
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PCT/US2012/041070
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French (fr)
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WO2013109302A3 (en
Inventor
Shari Spector
Robert Smith
Joe Orlando
Nanying Bian
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Emd Millipore Corporation
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Priority to RU2013154493/10A priority Critical patent/RU2595430C2/en
Priority to AU2012366229A priority patent/AU2012366229C1/en
Publication of WO2013109302A2 publication Critical patent/WO2013109302A2/en
Publication of WO2013109302A3 publication Critical patent/WO2013109302A3/en
Priority to IL229774A priority patent/IL229774A/en
Priority to AU2017200616A priority patent/AU2017200616B2/en
Priority to IL253992A priority patent/IL253992B/en
Priority to AU2019200368A priority patent/AU2019200368B2/en

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
    • C07K14/195—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from bacteria
    • C07K14/305—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from bacteria from Micrococcaceae (F)
    • C07K14/31—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from bacteria from Micrococcaceae (F) from Staphylococcus (G)
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D15/00—Separating processes involving the treatment of liquids with solid sorbents; Apparatus therefor
    • B01D15/08—Selective adsorption, e.g. chromatography
    • B01D15/26—Selective adsorption, e.g. chromatography characterised by the separation mechanism
    • B01D15/38—Selective adsorption, e.g. chromatography characterised by the separation mechanism involving specific interaction not covered by one or more of groups B01D15/265 - B01D15/36
    • B01D15/3804—Affinity chromatography
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D15/00—Separating processes involving the treatment of liquids with solid sorbents; Apparatus therefor
    • B01D15/08—Selective adsorption, e.g. chromatography
    • B01D15/26—Selective adsorption, e.g. chromatography characterised by the separation mechanism
    • B01D15/38—Selective adsorption, e.g. chromatography characterised by the separation mechanism involving specific interaction not covered by one or more of groups B01D15/265 - B01D15/36
    • B01D15/3804—Affinity chromatography
    • B01D15/3809—Affinity chromatography of the antigen-antibody type, e.g. protein A, G, L chromatography
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/281—Sorbents specially adapted for preparative, analytical or investigative chromatography
    • B01J20/286—Phases chemically bonded to a substrate, e.g. to silica or to polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/32—Impregnating or coating ; Solid sorbent compositions obtained from processes involving impregnating or coating
    • B01J20/3231—Impregnating or coating ; Solid sorbent compositions obtained from processes involving impregnating or coating characterised by the coating or impregnating layer
    • B01J20/3242—Layers with a functional group, e.g. an affinity material, a ligand, a reactant or a complexing group
    • B01J20/3268—Macromolecular compounds
    • B01J20/3272—Polymers obtained by reactions otherwise than involving only carbon to carbon unsaturated bonds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/32—Impregnating or coating ; Solid sorbent compositions obtained from processes involving impregnating or coating
    • B01J20/3231—Impregnating or coating ; Solid sorbent compositions obtained from processes involving impregnating or coating characterised by the coating or impregnating layer
    • B01J20/3242—Layers with a functional group, e.g. an affinity material, a ligand, a reactant or a complexing group
    • B01J20/3268—Macromolecular compounds
    • B01J20/3272—Polymers obtained by reactions otherwise than involving only carbon to carbon unsaturated bonds
    • B01J20/3274—Proteins, nucleic acids, polysaccharides, antibodies or antigens
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K1/00—General methods for the preparation of peptides, i.e. processes for the organic chemical preparation of peptides or proteins of any length
    • C07K1/14—Extraction; Separation; Purification
    • C07K1/16—Extraction; Separation; Purification by chromatography
    • C07K1/22—Affinity chromatography or related techniques based upon selective absorption processes
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
    • C07K16/12—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from bacteria
    • C07K16/1267—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from bacteria from Gram-positive bacteria
    • C07K16/1271—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from bacteria from Gram-positive bacteria from Micrococcaceae (F), e.g. Staphylococcus
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2319/00—Fusion polypeptide
    • C07K2319/20—Fusion polypeptide containing a tag with affinity for a non-protein ligand
    • C07K2319/21—Fusion polypeptide containing a tag with affinity for a non-protein ligand containing a His-tag

Definitions

  • the present invention relates to chromatography matrices including ligands based on one or more domains of immunoglobulin-binding proteins such as, Staphylococcus aureus Protein A (SpA) as well as methods of using the same.
  • immunoglobulin-binding proteins such as, Staphylococcus aureus Protein A (SpA)
  • Ligands used in affinity chromatography typically confer a high selectivity for the target molecule, thereby resulting in high yield,, high purity and fast and economical purification of target molecules.
  • Staphylococcus aureus Protein A- based reagents and chromatography matrices have found a widespread use in the field of affinity chromatography for capture and purification of antibodies and Fc- containing proteins as well as in analytical-scale antibody detection methods due to its ability to bind IgG, without significantly affecting the affinity of the immunoglobulin for antigen.
  • matrices In order to maintain selectivity of the chromatography ligands including ligand bound solid supports such as SpA bound chromatography matrices, matrices have to be cleaned and are typically cleaned under acidic or alkaline conditions, e.g.. with sodium hydroxide (NaOH).
  • NaOH sodium hydroxide
  • a standard process which is used for cleaning and restoring the matrix is a eleaning-iii-place (CIP) alkaline protocol, which typically involves treatment of the ligand bound matrix with NaOH concentration ranging from 0.05M to I , resulting in pl l range 1 2.7 to 14.0.
  • CIP eleaning-iii-place
  • Protein A based chromatography matrices have been previously described in the art which appear to show a reduced loss of binding capacity for a target molecule following treatment with alkaline conditions. See. e.g.. U.S. Patent Publication No. 20100221 844. which describes affinity chromatography matrices incorporating wild-type (wt) B or Z domains of SpA with multiple point attachment to the matrix, which show up to 95% of the initial binding capacity even after exposure to 0.5 ' M NaOH for 5 hours or more. Also, U.S. Patent Publication No.
  • 20100048876 describes a chromatography matrix incorporating wild type C domain of SpA as well as a C domain containing a deletion of amino acid residues 3 through 6, which appear to show up to 95% of the initial binding capacity after exposure to 0.5M for about 5 hours. These ligands are immobilized via a cysteine directed single-point attachment to the matrix. Further, chromatography matrices have been described which
  • Protein A domains containing mutations at one or more asparagine residues of the protein where the matrices appear to show a reduced . loss in binding capacity relative to the wi ld type SpA, fol lowing exposure to alkaline conditions and appear to be immobilized via a single-point attachment to the matrix. See, e.g.. U.S. Patent No. 6,8 1 , 161 .
  • affinity chromatograph matrices appear to show a reduced loss in binding capacity for a target molecule following exposure to caustic conditions
  • some of these matrices appear to show a large degree of fragmentation of l igand, e.g., as observed using SDS-PAGE and/or size exclusion chromatography (SEC), following exposure to caustic conditions.
  • SEC size exclusion chromatography
  • Such fragmentation is undesirable, as a large degree of fragmentation of ligand results in smaller fragments of ligands being present which are more difficult to remove and separate from the target molecule, thereby increasin the likelihood that such potentially immunogenic fragments will co-purify with the therapeutic target molecule.
  • a large degree of fragmentation results in an increased loss in binding capacity of the matrix for a target molecule.
  • the present invention provides affinity chromatography ligands and matrices incorporating the same, where the ligands are based on one or more
  • Staphylococcus aureu Protein A (SpA) domains having a deletion from the -terminus, starting at posit ion 1 or position 2 of the domain.
  • SpA Staphylococcus aureu Protein A
  • affinity chromatography matrices which includes one or more B domains of SpA having a deletion, one or more C domains of SpA having a deletion or one or more Z domains of SpA having, a deletion, where the one or more domains are attached to a solid support.
  • an affinity chromatography matrix according to the present invention includes a ligand attached to a solid support, vvhere the ligand comprises one or more B domains of Staphylococcus aureus Protein A (SpA), where at least one B domain comprises a deletion of at least 3 consecutive amino acids from the -
  • an affinity chromatography matrix according to the present invention comprises a ligand attached to a solid support, where the ligand comprises one or more C domains of Staphylococcus aureus Protein A (SpA).
  • at least one G domain comprises a deletion of at least 3 consecuti ve amino acids from the N-termirius.
  • an affinity chromatography matrix comprises a ligand attached to a solid support, where the ligand comprises t ⁇ vo or more B domains, two or more C domains or two or more Z domains, or any combination of B, C and Z domains, where at least one of B, C or Z domain comprises a deletion of at least 3 consecuti ve amino acids from the N-terminus.
  • the ligand comprises t ⁇ vo or more B domains, two or more C domains or two or more Z domains, or any combination of B, C and Z domains, where at least one of B, C or Z domain comprises a deletion of at least 3 consecuti ve amino acids from the N-terminus.
  • more than one site on each ligand is attached to a solid support (i.e.. multipoint attachment).
  • the ligand exhibits reduced fragmentation, as determined by SDS-PAGE or by size-exclusion chromatography (SEC), relative to its wt counterpart, following exposure of the ligand or the matrix containing the ligand to 0.5M NaOH for at least 5 hours.
  • SEC size-exclusion chromatography
  • the ligand comprises a deletion of 3 amino acids from the N-terminus, a deletion of 4 amino acids from the N-terminus or a deletion of 5 amino acids from the N-terminus, where more than one site on the ligand is attached to a solid support, thereby to form an affinity
  • a ligand has an amino acid sec)iience set forth in any of SEQ ID NOs: 13-42, SEQ ID NOs:55-84 and SEQ ID NOs: 93-94.
  • a ligand according to the present invention has the following structure:
  • X represents a B domain, a Z domain or a C domain of SpA
  • n represents the number of domains ranging from zero through (m-1 )
  • Y represents a B domain or a Z domain or a C domain of SpA having at least 3 consecutive amino acids deleted from the N-terminus
  • m represents the number of Y domains ranging from one through eight, where more than one site on the ligand is attached to a solid support (e.g., a chromatography matrix).
  • the ligand comprises two B domains or two Z domains or two C domains of SpA, or one B and one C domain, or one B and one Z domain, or one C and one Z domain, where at least one B domain or at least one Z domain or at least one C domain includes a deletion of three consecutive amino acids from the N-terminus or a deletion of four consecutive amino acids from the N-terminus or a deletion of five consecutive amino acids from the N-terminus. It is understood that the various domains may be arranged in any order.
  • a ligand according to the present invention comprises three B domains or three Z domains or three C domains, or any combination of B, C or Z domains in any order, where at least one B domain or at least one Z domain or at least one C domain comprises a deletion of three consecutive amino acids from the N- terminus or a deletion of four consecutive amino acids from the N-terminus or a deletion of five consecutive amino acids from the N-terminus.
  • a ligand according to the present invention comprises four B domains or lour Z domains or four C domains, or any combination of B.
  • At least one B domain or at least one Z domain or at least one C domain comprises a deletion of three consecutive amino acids from the N- terminus or a deletion of four consecutive amino acids from the N-terminus or a deletion of live consecutive amino acids from the N-terminus.
  • a ligand according to the present invention comprises ive B domains or five Z domains or five C domains, or any combination of B, Z or C domains in any order, where at least one B domain or at least one Z domain or at least one C domain comprises a deletion of three consecutive amino acids from the N-terminus or a deletion of four consecutive amino acids from the N-terminus or a deletion of five consecutive amino acids from the N-terminus.
  • a l igand according to the present invention comprises six B domains or six Z domains or six C domains, or any combination of B, Z or C domai ns in any order, where at least one B domain or at least one Z domain or at least one C domain comprises a deletion of three consecuti ve amino acids from the N-terminus or a deletion of four consecutive amino acids from the N-terminus or a deletion of five consecutive amino acids from the N-terminus.
  • a ligand according to the present invention comprises seven B domains or seven Z domains or seven C domains, or any combination of B; Z or C domains in any order, where at least one B domain or at least one Z domain or at least one C domain comprises a deletion of three consecutive amino acids from the N- terminus or a deletion of four consecutive amino acids from the N-terminus or a deletion of live consecutive amino acids from the N-terminus.
  • a ligand according to the present invention comprises eight B domains or eight Z domains or eight C domains, or any combination of B, Z or C domains in any order, where at least one B domain or at least one Z domain or at least one C domain comprises a deletion of three consecutive amino acids from the N- terminus or a deletion of four consecutive amino acids from the N-terminus or a deletion of five consecutive amino acids from the N-terminus.
  • a method of affinity puri fying one or more target molecules from a sample
  • the method comprises the steps of: (a) providing a sample comprising one or more target molecules (e.g., immunoglobulins or Fc-containing proteins); (b) contacting the sample with a matrix according to the invention under conditions such that the one or more target molecules (e.g.. immunoglobulins or Fc-containin proteins) bind to the matrix; and (c) recovering the one or more bound target molecules (e.g.. immunoglobulins or Fc- containing proteins) by eluting under suitable conditions such as. for example, a suitable pH.
  • an affinity chromatography matrix according to the present invention retains at least 95% of its initial binding capacity for a target molecule after 5 hours, or after 10 hours, or after 15 hours, or after 20 hours, or after 25 hours, or after 30 hours of incubation in 0.5 M NaOH.
  • an affinity chromatography matrix according to the present invention retains at least 95% of its initial binding capacity after 5 hours incubation in 0.5M NaOH.
  • an affinity chromatography matrix according to the present invention retains at least 95% of its initial binding capacit for a target molecule after 25 hours incubation in 0, 1 NaOH; at least 85% of its initial binding capacity for a target molecule after 25 hours incubation in 0.3M NaOH; or at least 65% of its initial binding capacity for a target molecule after 25 hours incubation in 0.5M NaOH.
  • immunoglobulins which are capable of being bound by the various ligands described herein include., e.g., IgG. IgA and IgM, or any. fusion protein comprising an antibody and any fragment of antibody, which is capable of binding to SpA.
  • nucleic acid molecules encoding the various ligands described herein, as well as host cells including such nucleic acid molecules.
  • a host cell is a prokaryotic cell. In other embodiments, a host cell is a eukaryotic cell.
  • the present invention provides SpA-based affinity chromatography matrices which exhibit altered (increased or decreased) binding to a Fab portion of an immunoglobulin compared to the wt SpA ligands, while retaining the ability to bind the Fc portion of the immunoglobulin.
  • an SpA-based matrix according to the present invention exhibits a decreased binding to a Fab portion of an immunoglobulin compared to wt SpA.
  • a chromatography matrix incorporates a SpA ligand. which includes a lysine at position 29. instead of a glycine (in Case of B and C domains of SpA) or instead of an alanine (in case of the Z domain of SpA).
  • FIG. 1 depicts the amino-acid sequence alignments for the wild type
  • FIG. 2 depicts schematic diagrams of the plasmid ETl 1 a containing the nucleic acid sequence encoding the dimeric Z domain ligand with a A29K mutation, the amino acid sequence shown in SEQ ID NO:85 (control), and plasmid pETl l a containing the nucleic acid sequence encoding the dimeric Z domain ligand with a A29K mutation as well as the second domain including a deletion of 4 consecutive amino acids from the N-terminus, the amino acid sequence shown in SEQ ID NO: 78.
  • the ligand constructs further include a His-tag sequence at the 3' end.
  • Figure 3 is a Copmassie stained SDS-PAGE gel fo analyzing the fragmentation pattern of free and immobilized dimeric Z and C ligands with or without caustic soak in 0.5M NaOH for 25 hrs.
  • the description of the, various Lanes of the SDS-PAGE gel is as follows.
  • Lane I molecular marker: Lane 2: dimeric Z domain ligand with no caustic exposure (A29K with no deletions, shown in SEQ ID NQ:85, which is used as the control and includes a His-tag): Lane 3: the dimeric Z domain ligand control subjected to 0.5M NaOH soak for 25 hours; Lane 4: the dimeric Z domain ligand control immobilized onto an agarose chromatography resin, which is subjected to 0.5.M NaOH. ' soak for 25 hours; Lane ,5: the dimeric Z domain ligand having a deletion of 4 consecutive amino acids from the N-terminus of the second domain (A29K.
  • Lane 6 the dimeric Z domain ligand of ' SEQ ID NO:78 with a His-tag subjected to 0.5M NaOH soak for 25 hours
  • Lane 7 the dimeric Z domain ligand of SEQ ID NQ:78 with a His-tag immobilized onto an agarose chromatography resin and subjected to 0.5 M NaOH soak for 25 hours
  • Lane 8 dimeric C domain ligand with no deletions used as a control (amino acid sequence shown in SEQ ID NO:92 plus having a His-tag) With no caustic exposure:
  • Lane 9 the dimeric C domain ligand control subjected to 0.5M NaOH soak for 25 hours
  • Lane 10 the dimeric C domain ligand immobilized onto an agarose, chromatography resin and subjected to 0.5M NaOH soak for 25 hours:
  • Lane 1 1 dimeric C domain ligand having a deletion, shown in SEQ ID NO:78 and a His-tag
  • the .v-axis denotes the rentenlion time in minutes with smaller molecules having longer retention time than that of a larger molecule.
  • the v-axis represents UV absorption at 280 nm in niAU.
  • the evidence of reduced fragmentation for the dimeric Z and C domain ligands having a N-terminus deletion in the second domain, following extended caustic soak (i.e., 0.5M NaOH soak for 25 hours), is shown by way of boxes on the chromatogram and the presence of smaller fragments for the dimeric Z and C domain controls is shown by way of arrows.
  • Figure 5 is a Coomassie stained SDS-PAGE gel for analyzing the fragmentation pattern of both free and immobilized pentameric Z domain ligands .with or without caustic soak in 0.5 NaOH for 25 hours.
  • the description of the various lanes of the SDS-PAGE gel is as follows: Lane 1 : molecular weight marker; Lane 2: pentameric Z domain ligand having the A29 mutation and a deletion of 4 consecuti ve amino acids from the N-terminus of all but the first domain, the amino acid sequence of which is set forth in SEQ ID NO:84.
  • Lane 3 pentameric Z domain ligand of SEQ ID NO:84 subjected to 0.5M NaOH soak for 25 hours; Lane 4: pentameric Z domain ligand of SEQ ID NO:84 immobilized onto an agarose chromatography resin and subjected to 0.5 NaOH soak for 25. hours; Lane 5: pentameric Z domain ligand of SEQ ID NO:91 .
  • Lane 6 pentameric Z domain ligand control subjected to 0.5N NaOH soak for 25 hours
  • Lane 7 pentameric Z domain ligand control immobilized onto an agarose chromatography resin and subjected to 0.5M NaOH soak for 25 hours.
  • Lanes 8, 9 and 10 relate to the results seen with subjecting rSPA to a similar treatment, where Lane 8 represents rSPA which is not subjected to any caustic soak; Lane 9 represents rSPA subjected to 0.5M NaOH soak for 25 hours and immobilized rSPA subjected to 0.5M NaOH soak for 25 hours.
  • the bands represent the fragmentation, as depicted by arrows.
  • Figure 6 is a chromatogram of an SEC analysis of the pentameric Z domain ligands summarized in the description of Figure 5 above.
  • the x-axis denotes the rentention time in minutes with smaller molecules having longer retention time than that of a larger molecule.
  • the v-axis represents LTV absorption at 280 nm in mAU.
  • the evidence for reduced fragmentation in case of the pentameric Z domain ligands having a N-terminal deletion in all but the first domain, following extended caustic soak, is shown by way of boxes on the chromatogram and the presence of smaller fragments seen with the pentameric Z domain control is shown by way of an arrow pointing to the fragments. Further, extensive amount of fragmentation seen for rSPA can be also observed using SEC.
  • FIG. 7 is a chromatogram of an SEC analysis of the immobilized pentameric Z domain ligands summarized in the description of Figure 5 above.
  • the -axis denotes the rentention time in minutes with smaller molecules having longer retention time than that of a larger molecule.
  • the y-axis represents U V absorption at 280 nm in mAU ' .
  • T he evidence for reduced fragmentation in case of the immobilized pentameric Z domain ligand having an N-terminal deletion in the second domain, following extended caustic soak, is shown by way of a box on the chromatogram and the presence of smaller fragments seen with the pentameric Z domain control is shown by way of an arrow pointing to the fragments. Further, extensive amount of fragmentation seen for immobilized rSPA can be also observed using SEC.
  • Figure 8 is a chromatogram of an S EC analysis of the free dimeric Z domain ligands following extended caustic soak, where the ligands include a N- terminus deletion of the first one (SEQ ID NO:87).
  • first t wo SEQ I D O:SS
  • first three SEQ ID NO:69
  • first four SEQ ID NO:78
  • the x-axis denotes the rentention time in minutes with smaller molecules having longer retent ion time than that of a larger molecule.
  • the y-axis represents UV absorption at 280 nm in mAU.
  • fragmentation in case of the dimeric ligands having first three or first four amino acids deleted from the .N -terminus of the second domain following extended caustic soak is depicted by boxes.
  • the presence of fragmentation observed following extended caustic soak of the dimeric ligands having no amino acid deletions (SEQ ID NO:85) or the first amino acid deleted or the first two amino acids deleted from the N- terminus of the second domain, is shown by way of arrows pointing to the presence of fragments on the chromatogram.
  • Figure 9 compares the retained binding capacities of immobilized C domain pentameric ligands after repeated caustic exposure, where one pentameric ligand includes an N terminus deletion of 4 amino acids in each domain, the G29K mutation in each domain as well as an alanine as the very first amino acid in the pentamer (the amino acid sequence shown in SEQ ID NO:93): and the other pentameric ligand being its wt counterpart with the G29 K mutation (the amino acid sequence of which is shown in SEQ ID O:95).
  • the .v-axis represents time of cumulative exposure of the chromatography matrices to 0.7 NaOH over 16 cycles of 30 mins each.
  • the j'-axis represents the percent retained binding capacity.
  • the present invention provides affinity chromatography matrices which incorporate ligands based on one or more domains of SpA, where the ligands, either alone or when immobilized onto a matrix, show reduced fragmentation during use in puri ication processes, relative to the corresponding wt domains of SpA.
  • SpA-based chromatography ligands include, for example, those described in U.S. Patent Publication No. 20100221844. which describes chromatography matrices which incorporate wild type B and Z domains of SpA, where more than one site on the ligand is attached to a
  • chromatography matrix i.e.. multipoint attachment
  • U.S. Patent No. 6,83 1 , 161 which discusses SpA-based alkaline based chromatography ligands where one or more asparagine amino acid residues hav been modified.
  • ligands described in U.S. Publication No. 20100221 844 which is highly undesirable.
  • the ligands described herein are far more attractive candidates for protein purification compared to the previously described ligands, in that they show reduced iragmentation following exposure to alkaline conditions during the regeneration and cleaning-in-place (CIP) protocols that are routinel used in protein purification processes.
  • SpA refers to a 42Kda multf-domain protein isolated from the bacterium Staphylococcus aureus.
  • SpA is bound to the bacterial cell wall via its carboxy-terminal cell wall binding region, referred to as the X domain.
  • X domain carboxy-terminal cell wall binding region
  • E, D, A, B, and C imnninoglobulin-binding domains
  • Each of the E, D, A, B and C domains of SpA possess distinct Ig- binding sites.
  • One site is for Fey (the constant region of IgG class of Ig) and the other is for the Fab portion of certain Ig molecules (the portion of the Ig that is responsible for antigen recognition). It has been reported that each of the domains contains a Fab binding site.
  • the non-lg binding portion of SpA is located at the C-terminus and is designated the X region or X-domain.
  • T he Z domain of SpA is an engineered analogue of the B domain of
  • SpA and includes a valine instead of an alanine at position 1 and an alanine instead of a.glycine residue, at position 29 (Nilsson. e «/., Protein engineering. Vol. 1. No. 2, 107-113, 1987.).
  • an affinity ligand comprises one or more B domains or one or more Z domains or one or more C domains, or any combinations thereof where at least one B domain or at least one Z domain or at least one C domain comprises a deletion of 3 consecutive amino acids from the N-terminus, or 4 consecutive amino acids from the N-terminus or 5 consecutive amino acids from the N-terminus, startin at position 1 or at position 2.
  • more than one site of an affinity ligand is attached to a chromatography matrix (i.e., multipoint attachment).
  • the present invention provides an affinity chromatography matrix comprising one or more B domains of SpA attached to a chromatography matrix, where more than one site of the ligand is attached to the matrix and where at least one B domain has a deletion of 3. consecutive amino acids from the, N-terminus or 4 consecutive amino acids from the N-terminus. or 5 consecutive amino acids from the N-terminus, starting at position 1 or at position 2 of the wt B domain sequence.
  • the present invention provides an affinity chromatography matrix comprising one or more Z domains of SpA attached, to a chromatography matrix, where more than one site of the ligand is attached to the matrix and where at least one Z domain has a deletion of 3 consecutive amino acids from the N-terminus or 4 consecutive amino acids from the N-terminus or 5 consecutive amino acids from the N-terminus. starting at position ,1 or position 2 of the wt Z domain sequence.
  • the present invention provides an affinity chromatography matrix comprising one or more C domains of SpA, attached to a chromatography matrix, where more than one site of the ligand is attached to the matrix and where at least one C domain has a deletion of 3 consecutive amino acids from the N-lerminus or 4 consecutive amino acids from the N-terminus or 5 consecutive amino acids from the N-terminus, starting at position 1 or al position 2 of the wt C domain sequence.
  • the present invention provides an alkaline stable affinity chromatography ligand which includes five C domains of SpA. with each domain including a G29 mutation as well as 4 amino acids deleted from the N-terminus, starting at position 1 , and the pentameric form including an extra alanine as the first amino acid to facilitate homogeneous post translational processing of the protein.
  • SpA ligands described herein further include the glycine amino acid residue at position 29 replaced with a lysine amino acid residue (in case of B and C domains) or the alanine amino acid residue at position 29 replaced with a lysine amino acid residue (in case of Z domain).
  • parental molecule or wild-type (wt) counterpart or "wt protein " or “wt domain,” ' as used herejii is intended to refer to a corresponding protei n (SpA) or a domain of a protein (e.g., B, Z or C domai ns of SpA) in its substantially native form., which is generally used as a control herein.
  • a w counterpart control, as used herein, which corresponds to a SpA domain in its substantially native form may include one amino acid change from the corresponding SpA domain to alter Fab binding; however, is otherwise. identical in sequence to the corresponding wt domain.
  • the ligands according to the present invention exhibit reduced fragmentation (in case of both free and immobilized forms) relative to their wt counterparts (i.e.. completely wt or including a mutation to alter Fab binding), as evidenced by the. experiments discussed in the Examples herein.
  • the wt counterpart of a B domain or C domain based ligand according to the present invention is the wt B domain of SpA or wt C domain of SpA, the amino acid sequences of which are set forth in SEQ ID NO:3 and SEQ JD Q:4.
  • a wt counterpart of a Z domain based ligand is the Z domain amino acid sequence set forth in SEQ ID NO:6.
  • a wt counterpart of a B, C or Z domai n is substantially identical to the sequence of the B, C or Z domain mentioned above, but for a mutation at position 29 to alter the Fab-binding of the domain. Accordingly, in certain embodiments, a t counterpart of a B domain based ligand includes the amino acid sequence set forth in SEQ ID NO:45 (G29K), a wt counterpart of a C domain based ligand includes the amino acid sequence set forth in SEQ ID NO:46 (G29K) and the wt counterpart of a Z domain based ligand includes the amino acid sequence set forth in SEQ ID NO:48 (A29K).
  • a wt counterpart of a pentameric C domain ligand according to the present invention includes the. amino acid sequence set forth in SEQ ID NO: 95 or in SEQ ID NO:96.
  • sequence identity means that two nucleotide or amino acid sequences, when optimally aligned, such as by the programs GAP or BESTFIT using default gap weights, share at least 70% sequence identity, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity or more.
  • sequence comparison typically one sequence acts as a reference sequence (e.g.. parent sequence), to which test sequences are compared.
  • reference sequence e.g.. parent sequence
  • sequence comparison algorithm test and reference sequences are input into a computer, subsequence coordinates are designated, if necessary, and sequence algorithm program parameters are designated. The sequence comparison algorithm then calculates the percent sequence identity for the lest sequence(s) relative to the reference sequence, based on the designated program parameters.
  • Optimal alignment of sequences for comparison can be conducted, e.g., by the local homology algorithm of Smith & Waterman. Adv. Appl. Math. 2:482 ( 1981), by the homology alignment algorithm of Needleman & Wunsch, J. Mol. Biol. 48:443 (1970), by the search for similarity method of Pearson & Lipman, Pru . N i 'l. Acad. Sci. USA 85:2444 ( 1988), by computerized implementations of these algorithms (GAP, BESTFIT, FASTA, and TFASTA in the Wisconsin Genetics Software Package, Genetics Computer Group, 575 Science Dr., Madison, Wis.), or by visual inspection (see generally Ausubel et al.. Current Protocols in Molecular Biology).
  • BLAST algorithm One example of algorithm that is suitable for determining percent sequence identity and sequence similarity is the BLAST algorithm, which is described in Altschul et al.. J. Mol. Biol. 215:403 (1990).
  • Software for performing BLAST analyses is publicly available through the National Center for Biotechnology Information (publicly accessible through the National Institutes of Health NCBI internet server).
  • default program parameters can be used to perform the sequence comparison, although customized parameters can also be used.
  • the BLASTP program uses as defaults a wordlengih (W) of 3, an expectation (E) of 10, and the BLOSUM62 scoring matrix (see Henikoff & Henikoff, Proc. Natl. Acad. Sci. USA 89: 1091 5 ( 1989)).
  • E domain of Staphylococcus aureus Protein A refer to the polypeptide whose amino acid sequence is set forth in SEQ ID NO: 1 or that encoded by, e.g.. the nucleotide sequence set forth in SEQ ID NO:7.
  • the "E domain” is a 51 amino acid polypeptide that folds into a three-helix bundle structure. It is capable of binding Fc via residues on the surface of helices I and 2, or to Fab via residues on the surface of helices 2 and 3.
  • D domain As used interchangeably herein, the terms "D domain, " "D domain of SpA, " and “D domain of Staphylococcus aureus Protein A.” refer to the polypeptide whose amino acid sequence is set forth in SEQ I D NO:5 or that encoded by e.g.. the nucleotide sequence set forth in SEQ ID NO: l I .
  • the "D domain” is a 61 amino acid polypeptide that folds into a three-helix bundle structure. It is capable of Fc binding via residues on the surface of helices 1 and 2. or to Fab via residues on the surface of helices 2 and 3.
  • 'A domain As used interchangeably herein, the terms : 'A domain,” “A domain of SpA, “ and “A domain of Staphylococcus aureus Protein A,” refer to the polypeptide whose amino acid sequence is set forth in SEQ ID NO:2 or that encoded by, e.g., the nucleotide sequence set forth in SEQ ID NO:8.
  • the "A domain” is a 58 amino acid polypeptide that folds into a three-helix bundle structure. It is capable of Fc binding via residues on the surface of helices 1 and 2. or to Fab via residues on the surface of helices 2 and 3.
  • B domain As used interchangeably herein, the terms "B domain.” “B domainof SpA,” and “B domain of Staphylococcus aureus Protein A, " refer to the polypeptide whose amino acid sequence is set forth in SEQ ID NO:3 or that encoded by, e.g.. the nucleotide sequence set forth in SEQ I D NO:9.
  • the "B domain” is a 58 amino acid polypeptide that folds into a three-helix bundle structure. It is capable of Fc binding via residues on the surface of helices 1 and 2, or to Fab via residues on the surface of helices 2 and 3.
  • a B domain based ligand according to the present invention includes a deletion of three amino acids from the N-terminus. e.g., having the amino acid sequence set forth in SEQ ID NO: 13.
  • a B domain based ligand according to the present invention includes a deletion of four amino acids from the N-terminus. e.g.. having the amino acid sequence set forth in SEQ I D NO:28.
  • a B domain based ligand according to the present invention includes a deletion of five amino acids from the N-terminus (sequence not shown).
  • C domain of Staphylococcus aureus Protein A refers to the polypeptide whose amino acid sequence is set forth in SEQ I D NO:4 or that encoded by. e.g.. the nucleotide sequence set forth in SEQ ID NO: 10.
  • the "C domain” * is a 58 amino acid polypeptide that folds into a three-helix bundle structure. It is capable of Fc binding via residues on the surface of helices I and 2. or to Fab via residues on the surface of helices 2 and 3.
  • a C domain based ligand according to the present invention includes a deletion of three amino acids from the N-terminus.-e. ⁇ ., having the amino acid sequence set forth in SEQ ID NO: 14.
  • a C domain based ligand according to the present invention includes a deletion of four amino acids from the N-terminus, e.g.. having the amino acid sequence set forth in SEQ ID NO:29.
  • a C domain based ligand according to the present invention includes a deletion of five amino acids from the N-terminus (sequence not shown).
  • SpA and Z domain of Protein A refer to the three helix, 58 amino acid polypeptide that is a variant of the B domain of protein A.
  • the amino acid sequence of the Z domain is set forth in SEQ ID NO:6 and the nucleic acid sequence is set forth in SEQ ID NO: 12.
  • An exemplary Z domain is described in Nilsson el a!.. Protein Engr. f 1 .-107-1 13 ( 1 87), the entire contents of which are incorporated by reference herein.
  • a Z domain based ligand according to the present invention includes a deletion of three amino acids from the N-terminus. e.g., having the amino acid sequenc set forth in SEQ ID NO: 1 5. In other embodiments, a Z domain based ligand according to the present invention includes a deletion of four amino acids from the N-terminus, e.g., having the amino acid sequence set forth in SEQ ID NO:30. In another embodiment, a Z domain based ligand according to the present invention includes a deletion of five amino acids from the N-terminus (sequence not shown).
  • more than one site of the ligands described herein is attached to a solid support (i.e., multipoint attachment) and where the ligands show reduced fragmentation (in case of both free and attached ligands) during use in purification processes, as evidenced by SDS-PAGE or SEC.
  • reduced fragmentation refers to a decrease in the number and/or intensity of fragments of a ligand. as seen on an SDS- PAGE gel or by SEC. relative to a wt counterpart of the ligand, following exposure of the free ligand molecule or the ligand molecule immobilized onto a solid support, to alkaline conditions during the purification process.
  • the ligand is immobilized onto a solid support via multipoint attachment. Fragmentation is usually detected by the presence of lower molecular bands relative to the intact molecule on an SDS-PAGE gel or as distinct peaks having different retention times on an SEC chromatogram.
  • the SpA ligands according to the present invention exhibit reduced fragmentation, which can be detected as follows.
  • the free ligand can be exposed directly to 0.1 M NaOH, 0.3 NaOH or 0.5.M NaOH for 25 hrs, followed by a pH adjustment to 7.0 and can be subsequently analyzed by SDS-PAGE or SEC using standard protocols.
  • a ligand immobilized onto a chromatography matrix can be exposed to 0.1 M NaOH, 0.3M NaOH or 0.5 NaOH for 25 hrs.
  • the caustic supernatant is subsequently separated from the matrix (e.g.. a resin) and neutralized to pH 7. This supernatant can then be analyzed by SDS-PAGE or by SEC using standard protocols.
  • the relative optical intensity of the fragments can be observed visually and compared to a suitable control (e.g., a wt domain of SpA or an SpA domain containing a mutation at position 29, as described herein).
  • a suitable control e.g., a wt domain of SpA or an SpA domain containing a mutation at position 29, as described herein.
  • a typical purification process using an affinity chromatography matrix im olves regeneration of the matrix after each cycle of use employing an acidic or an alkaline solution, the latter being preferable.
  • typical processes also involve CIP steps, which employ use of an acidic or alkaline solution to sanitize the matrix, alkaline solutions being preferable.
  • an affinity chromatography matrix is expected to be exposed to several cycles of regeneration and CIP steps in its lifetime, thereby resulting in a significant loss in binding capacity for a target molecule over time.
  • chromatography matrices incorporating the ligands according to the present invention are alkaline stable in addition to exhibiting reduced
  • fragmentation during use in puri fication processes in that they show a reduced loss of binding capacity for a target molecule over time, following extended exposure to alkaline conditions during regeneration and CI P steps.
  • alkaline-stable " "alkaline stabi lity, " “caustic stable” or “ caustic stability, " as used herein, generally refers to the ability of an affinity ligand according to the present invention, either alone or when immobilized onto a chromatography matrix, to withstand repeated regeneration and CIP cycles using alkaline wash without losing its initial binding capacity. In general, it is assumed that a matrix by itself, onto which a ligand according to the invention is immobilized, contributes to less than a 5% change in stability after having been soaked in 0.5M NaOH for up to 30 hours.
  • affinity ligands according to the invention are able to withstand conventional alkaline cleaning for a prolonged period of time, which renders the ligands attractive candidates, especial ly for cost-effective large-scale purification of immunoglobulins and Fc-containing proteins, many of which are therapeutic molecules.
  • alkaline stabil ity refers to the ability of a ligand according to the present i nvention or a matrix incorporating. a ligand according to the present invention, to retain at least 65%, or at least 70%, or at least 75%, or at least 80%, or at least 85%, or at least 90%, or at least 95% of its initial binding capacity after 5 hours, or after 10 hours, or after 1 5 hours, or after 20 hours, or after 25 hours, or after 30 hours of incubation in 0.05 NaOH, O. lM NaOH, 0.3M NaOH or 0.5 ' M NaOH.
  • alkaline stability refers to a decrease in the initial binding capacity of the ligand by less than 70%, or less than 60%, or less than 50%, or less than 40%, or less than 30% even after treatment with 0.05M NaOH, 0. 1 M NaOH, 0.3 NaOH or 0.5M NaOH for 5 hours or 7.5 hours or 10 hours or 1 5 hours or 20 hours or 25 hours or 30 hours.
  • a chromatography matrix incorporating a ligand according to the present invention retains up to 95% of its initial binding capacity after exposure to 0.5N NaOH for 5 hours.
  • a chromatography matrix incorporating a ligand according to the present invention retains up to 95% of its initial binding capacity after exposure to 0. 1 M NaOH for 25 hours.
  • a chromatography matrix incorporating a ligand according to the present invention retains up to 85% of its initial binding capacity after exposure to 0.3 NaOH for 25 hours. In a further embodiment, a chromatography matrix incorporating a ligand according to the present invention retains up to 65% of its initial binding capacity after exposure to 0.5M NaOH for 25 hours.
  • SpA-based chromatography matrices according to the present invention exhibit an increased or improved alkaline stability as compared to matrices including wild type SpA domains. However, in other embodiments. SpA-based chromatography matrices according to the present invention are not more alkaline stable than the matrices including wild-type counterparts of the ligands.
  • One such example is a ligand based on the pentameric C domain of SpA which is not more alkaline stable than its wi ld-type pentameric C domain counterpart. It is understood that in certain instances, both the wild-type and the variants of SpA domains may include a G29 mutation to reduce Fab binding; however, such mutation does not itself have an effect on alkaline stability (data not shown).
  • Alkaline stability can be readily measured by one of ordinary skill in the art using routine experimentation and/or as described herein.
  • initial binding capacity refers to the amount of a target molecule (e.g., an immunoglobulin or an Fc-containing protein) that can be captured by a unit volume of an. affinity chromatography matrix (i.e., a matrix including an affinity ligand) prior to exposure of the matrix to alkaline conditions.
  • a target molecule e.g., an immunoglobulin or an Fc-containing protein
  • affinity chromatography matrix i.e., a matrix including an affinity ligand
  • affinity chromatography matrices including the ligands described herein exhibit less than 5%. or less than 6%, or less than 7%, or less than 8%, or less than 9%, or less than 10%. or less than 12%, or less than 1 5%, or less than 17%. or less than 20%, or less than 25%, or less than 30% loss in the initial binding capacity of a target molecule relative to an affinity chromatography matrix containing a corresponding wt SpA domain counterpart, as described herein, following extended exposure to caustic conditions.
  • the ligands described herein exhibit less than 5%. or less than 6%, or less than 7%, or less than 8%, or less than 9%, or less than 10%. or less than 12%, or less than 1 5%, or less than 17%. or less than 20%, or less than 25%, or less than 30% loss in the initial binding capacity of a target molecule relative to an affinity chromatography matrix containing a corresponding wt SpA domain counterpart, as described herein, following extended exposure to
  • the affinity chromatography matrices according to the present invention retain at least 95%, or at least 90%, or at least 85%, or at least 80%, or at least 75%, or at least 70% of the initial binding capacity of a target molecule relative to an affinity chromatography matrix containing a corresponding wt SpA domain counterpart, followin extended exposure to caustic conditions.
  • the chromatography matrices according to the present invention exhibit similar binding capacity to matrices containing wt counterpart of the ligand following extended exposure to caustic conditions.
  • One such exemplary chromatography matrix includes a ligand that includes 5 or more C domains of SpA, where each domain includes 4 amino acids deleted from the -terminus where the ligand is not more alkaline stable than its wild-type C domain counterpart. Both the deletion form and the wild-type counterpart may contain a G29K mutation.
  • the SpA ligands may further include a single amino acid such as, an alanine, a valine or a glycine, at the N- terminus of only the first domain in a multimer, where the extra amino acid facilitates homogeneous post-translational processing.
  • binding capacity of an affinity chromatography ligand for a target molecule can be readily measured using methods known in the art and those. described herein, e.g., as described in U.S. Patent Publication No. 20100221844. incorporated by reference herein in its entirety.
  • chromatography refers to a dynamic separation technique which separates a target molecule of interest (e.g.. an enzyme that catalyzes a hydrolysis of a target molecule of interest).
  • a mobile phase liquid or gas transports a sample containing the target molecule of interest across or through a stationary phase (normally solid) medium. Differences in partition or affinity to the stationary phase separate the different molecules while mobile phase carries the different molecules out at different time.
  • 'affinity chromatography refers to a mode of chromatography where a target molecule to be separated is isolated by i ts
  • affinity e.g. an alkaline, stable chromatography ligand
  • chromatography involves the addition of a sample containing a target molecule (e.g.. an immunoglobulin or an Fc-containing protein) to a solid support which carries on it an SpA-based ligand, as described herein.
  • a target molecule e.g. an immunoglobulin or an Fc-containing protein
  • Protein A affinity chromatography refers to the separation or isolation of substances using Protein A or SpA-based ligands.
  • Protein A affinity chromatography media/resin include those having the Protein A immobilized onto a controlled pore glass backbone, e.g., PROSEP ATM and PROSEP vATM media/resin
  • MILLI.PORE those having Protein A immobilized onto a polystyrene solid phase, e.g., the POROS 50ATM and Poros MabCapture ATM media/resin (APPLIED
  • BIOSYSTEMS, INC. those having Protein A immobilized on an agarose solid support, e.g., rPROTEIN A SEPHAROSE FAST FLOWTM or MABSELECTTM media or resins (GE HEALTHCARE).
  • Protein A may also be immobi lized onto a hydrophilic crossl inked polymer. See, e.g.. U.S. Patent
  • affinity matrix or "affinity chromatography matrix,” as used interchangeably herein, refers to a chromatographic support onto which an affinity chromatography ligand (e.g., SpA or a domain thereof) is attached.
  • the ligand is capable of binding to a molecule of interest through affinity interaction (e.g., an immunoglobulin or an Fc-containing protein) which is to be puri fied or removed from a mixture.
  • Exemplary Protein A based affinity chromatography matrices for use in Protein A based affinity chromatography which are known in the art include Protein A immobilized onto a control led pore glass backbone, e.g., the PROSEP ATM and PROSEP vATM resins, High Capacity, Ultra and PROSEP U ltra Plus
  • M1LLI PORE Protein A immobilized on a polystyrene solid phase, e.g. the POROS 50ATM resin and POROS abCapture ATM (APPLIED BIOSYSTEMS); or Protein A immobil ized on an agarose solid phase, for instance the rPROTEIN A SEPHAROSE FAST FLOWTM or MABSELECTTM resin (G E HEALTHCARE).
  • a polystyrene solid phase e.g. the POROS 50ATM resin and POROS abCapture ATM (APPLIED BIOSYSTEMS)
  • Protein A immobilized on an agarose solid phase for instance the rPROTEIN A SEPHAROSE FAST FLOWTM or MABSELECTTM resin (G E HEALTHCARE).
  • single-chain immunoglobulin or “single-chain antibody” (used interchangeably herein) refers to a protein having a t o-polypeptide chain structure consisting of a heavy and a light chain, said chains being stabilized, for example, by interchain peptide linkers, which has the ability to specifically bind antigen.
  • domain refers to a globular region of a heavy or light chain polypeptide comprising peptide loops (e.g.
  • Domains are further referred to herein as “constant” or “variable” , based on the relative lack of sequence variation within the domains of various class members in the case of a "constant” domain, or the significant variation within the domains of various class members in the case of a ''variable " domain.
  • Antibody or polypeptide “domains” are often referred to interchangeably in the art as antibody or polypeptide "regions " .
  • the "constant” domains of antibody l ight chains are referred to interchangeably as “light chain constant regions " , “light chain constant domains ' " “ .
  • Immunoglobulins or antibodies may be monoclonal or polyclonal and may exist in mononieric or polymeric form, for example, IgM antibodies which exist in pentameric form and/or IgA antibodies which exist in mononieric. dimeric or multimeric form.
  • fragment refers to a part or portion of an antibody or antibody chain comprising fewer amino acid residues than an intact or complete antibody or antibody chain. Fragments can be obtained via chemical or enzymatic treatment of an intact or complete antibody or antibody chain. Fragments can also be obtained by recombinant means. Exemplary fragments include Fab. Fab', F(ab')2, Fc and/or Fv fragments.
  • antigen-binding fragment refers to a polypeptide portion of an immunoglobulin or antibody that binds an antigen or competes with intact antibody ⁇ i. e. , with the intact antibody from which they were derived) for antigen binding (i.e.. speci fic binding). Binding fragments can be produced by recombinant DNA techniques, or by enzymatic or chemical cleavage of intact immunoglobulins. Binding fragments include Fab, Fab', F(ab') 2 , Fv, single chains, and single-chain antibodies.
  • fusion proteins including an antibody or fragment thereof as a part of the fusion protein.
  • polynucleotide and “nucleic acid molecule,” used interchangeably herein, refer to polymeric forms of nucleotides of any length, either ribonucleotides or deoxyribonucleotides. These terms include a single-, double- or triple-stranded DNA. genomic DNA, cDNA, RNA, DNA-RNA hybrid, or a polymer comprising purine and pyrimidine bases, or other natural, chemically or biochemically modified, non-natural or derivatized nucleotide bases.
  • the backbone of the polynucleotide can comprise sugars and phosphate groups (as may typically be found in RNA or DNA).
  • a double-stranded polynucleotide can be obtained from the single stranded polynucleotide product of chemical synthesis either by synthesizin the
  • a nucleic acid molecule can take many different forms, e.g., a gene or gene fragment, one or more exons, one or more introns, m ' RNA, cD ' NA, recombinant polynucleotides, branched polynucleotides, plasmids, vectors, isolated DNA of any sequence, isolated RNA of any sequence, nucleic acid probes, and primers.
  • a polynucleotide may comprise modified nucleotides, such as methylated nucleotides and nucleotide analogs, uracyl, other sugars and linking groups such as fluororibose and thioate, and nucleotide branches.
  • " ' DNA” or “nucleotide sequence” includes not only bases A, T, C. and G. but also includes any of their analogs or modified forms of these bases, such as methylated nucleot ides, internucleotide modi fications such as uncharged linkages and thioatcs, use of sugar analogs, and modified and/or alternative backbone structures, such as polyamides.
  • a nucleic acid molecule comprises a nucleotide sequence encoding a variant of SpA, as described herein.
  • Fc-binding ' 'binds to an Fc portion or “binding to an Fc portion” refers to the ability of an affinity ligand described herein, to bind to the constant part (Fc) of an antibody.
  • a ligand according to the present invention binds an Fc portion of an antibody (e.g.. human IgG l , IgG2 or lgG4) with an affinity of at least 10 "7 M. or at least 10 '8 M, or at least ⁇ 0 ' M.
  • Fab binding or “binding to a Fab portion” refers to the ability of an affinity ligand described herein, to bind to a Fab region of an antibody or an immunoglobulin molecule.
  • reduced binding to a Fab portion refers to any decrease in binding to a Fab (or F(ab) 2 ) portion of an immunoglobulin molecule by a SpA-based ligand according to the present invention relative to a control (e.g., a wt SpA domain), where the ligand further includes a mutation in one or more amino acids.
  • a ligand according to the present invention and its wt counterpart includes the glycine residue at position 29 replaced with an amino acid other than alanine or tryptophan.
  • a ligand according to the present invention includes a lysine residue at position 29.
  • binding to a Fab portion of an immunoglobulin molecule by a ligand described herein is undetectable using conventional techniques in the art and those described herein. Binding to an immunoglobulin molecule can be detected using well known techniques including those described herein and including but not limited to. for example, affinity chromatography and surface plasmon resonance analysis.
  • an immunoglobulin binding protein encompassed by the present invention binds an immunoglobulin molecule with an affinity of at least I 0 " '° .
  • * 'N-terminus refers to amino-terminus of the amino acid sequence of a SpA domain, starting at position 1 or at position 2 of the amino acid sequence of each of the domains, as depicted in Figure 1 .
  • the first amino acid in a sequence may be preceded by a methionine amino acid residue or another amino acid to facilitate homogenous post translational processing of the protein such as, for example, an alanine, a glycine or a valine.
  • the SpA ligands described herein include a deletion of at least 3.
  • a ligand according to the present invention includes 5 C domains, with each domain including a deletion of 4 consecutive amino acids from the N-terminus, starting at position 1.
  • amino acid sequence of the Z domain containing a deletion of 3 consecutive amino acids from the N-terminus is depicted in SEQ ID NO: 15; and that containing a deletion of 4 consecutive amino acids from the N-terminus is depicted in SEQ I D NO: 30.
  • ligands do not contain a deletion in the ' N-terminus of the first domain in the muitimeric form of ligand: however, subsequent domains in the ligand contain a delet ion of at least 3 consecutive amino acids from the N-terminus or at least 4 consecutive amino acids from the N-terminus or at least 5 consecutive amino acids from the N-terminus.
  • the SpA-based ligands according to the present invention harbor superior and unexpected properties, i.e., reduced fragmentation during use in purification processes, as evidenced by the Examples herein.
  • the teachings in the prior art appear to teach away from the motivation to make and use such ligands.
  • U.S. Patent Publication No. 20100048876 discusses a ligand which includes a deletion in amino acid residues 3 through 6 of the C domain of SpA; however, based on the teachings of this publication (see. e.g.. Figure 2 of U.S. Patent Publication No.
  • a dimer-only second domain has deletion 21
  • Z domain ⁇ 4 AA pentamer-first domain does not have deletion 42 wt E domain AA non-Fab (G29K) 43 wi A domain AA non-Fab (G29 ) 44 wt B domain AA non-Fab (G29K) 45 wt C domain AA non-Fab (G29 ) 46 wt D domain A A non-Fab (G29K) 47
  • B domain ⁇ 3 AA dimer-only second domain has deletion non-Fab 61 (G29K)
  • Z domain ⁇ 3 AA dimer-only second domain has deletion non-Fab 63 (A29K)
  • B domain ⁇ 4 AA dimer-only second domain has deletion non-Fab 76 (G29 )
  • Z domain ⁇ 4 AA dimer-only second domain has deletion non-Fab 78 (A29K)
  • a Domain ⁇ 4 AA dimer-first domain has a N-terminal deletion 89
  • D Domain ⁇ 4 AA dimer-first domain has a N-terminal deletion 90
  • SpA-based affinity chromatography ligands encompassed by the present invention can be made using any suitable methods known in the art.
  • a nucleic acid molecule encoding one or more domains of SpA having an N-terminus deletion can be cloned into a suitable vector for expression in an appropriate host cell.
  • suitable expression vectors are well-known in the art and typically include the necessary elements for the transcription and translation of the variant SpA coding sec
  • SpA molecules described herein may also be synthesized chemically from amino acid precursors for fragments using methods well known in the art. including solid phase peptide synthetic methods such as the Boc ' (tert- butyloxycarbonyl) or Fmoc (9-fluorenylmethyloxy carbonyl) approaches (see, e.g., U.S. Pat. Nos. 6,060.596; 4,879,378: 5.198.531 ; 5.240.680).
  • Expression of SpA molecules described herein can be accomplished in a variety of cells types such as, e.g., eiikaryolic host cells such as yeast cells, insect cells and mammalian cells and prokaryotie host cells, e.g.. bacteria such as E. coli.
  • SpA molecules may be expressed on the surface of a bacteriophage such that each phage contains a ON A sequence that codes for an individual SpA molecule displayed on the phage surface.
  • the affinity of the SpA molecule for an immunoglobulin can be readily assayed for using standard techniques in the art and those described herein, e.g.. EIJSA and BiacoreTM 2000 standard set up (BIACORE AB, Uppsala Sweden). It is desirable that the binding affinity of a SpA molecule of the present invention to an immunoglobulin is at least comparable with that of the parent molecule, where the molecule exhibits reduced fragmentation during use. as described herein.
  • SpA ligands encompassed by the present invention are immobilized onto a support, e.g., a solid support or a soluble support, to generate an affinity chromatography matrix suitable for the separation o
  • biomolecules such as, e.g.. immunoglobulins and Fc-containing proteins.
  • a ligand according, to the present invention is immobilized onto a solid support.
  • a solid support may be used for the attachment of a ligand according to the invention.
  • solid support matrices include, but are not limited to, controlled pore glass, silica, zirconium oxide, titanium oxide, agarose,, polymethacrylate, polyacrylate, poiyacrylamide. polyvinylelher, polyvinyl alcohol and polystyrene and derivatives thereof (e.g., alloys thereof).
  • a solid support may be a porous material or a non-porous material.
  • a solid support is a porous material.
  • a porous material used as a solid support may be comprised of a hydrophilic compound, a hydrophobic compound, an oleophobic compound, an oleophilic compound or any combination thereof
  • the porous material may be comprised of a polymer or a copolymer. Examples of suitable porous materials, include, but are not limited to polyether sulfone, polyamide, e.g.. nylon, polysaccharides such as, for example, agarose and cellulose, polyacrylate, polymethacrylate, poiyacrylamide.
  • poiymelhacrylamide polytetrafluoroeihylene, polysulfone. polyester, polyvinylidene fluoride, polypropylene, polyethylene, polyvinyl alcohol, polyvinylether, polycarbonate, polymer of a fluorocarbon, e.g. poly (tetrafiuoroelhylene-co- perfluoro(alkyl vinyl ether)), glass, silica, zirconia, titania, ceramic, metal and alloys thereof.
  • the porous material may be comprised of an organic or inorganic molecule or a combination of organic and inorganic molecules and may be comprised of one or more functional groups, e.g.. a hydroxy! group, an epoxy group, a thiol group, an amino group, a carbonyl group, or a carboxylic acid group, suitable for reacting, e.g.. forming covalent bonds for further chemical modification, in order to covalently bind to a protein.
  • the porous material may not possess a functional group but can be coated with a layer of material that bears functional groups such as, a hydroxyl group, a thiol group, an amino acid group, a carbonyl group, or a carboxylic acid group.
  • a conventional affinity separation matrix is used, e.g.. of organic nature and based on polymers that expose, a hydrophi lic surface to the aqueous media used, i.e. expose hydroxy (--Oi l) , , carboxy (— COOH), carbonyl (-CI IO. or RCO-R/), carboxamido (-CO Hi, possibly in N-substituted forms), amino (- l h, possibly in substituted form), oligo- or polyethylenoxy groups on their external and, i f present, also on internal surfaces.
  • the polymers may.
  • the solid support comprises porous agarose beads.
  • the various supports used in the present invention can be readily prepared according to standard methods known in the art, such as, for example, inverse suspension gelation described, e.g., in Hjerten. Biochim Biophys Acta 79(2), 393-398 ( 1 964).
  • the base matrices can be commercially available products, such as SepharoseTM I ' astFlow (GE H EALTHCARE. Uppsala. Sweden ).
  • the support is adapted to increase its rigidity, and hence renders the matrix more suitable for high flow rates.
  • the sol id support can be based on synthetic polymers, such as polyvinyl alcohol, polyvinylether, polyhydroxyalkyl acrylates,
  • polyhydroxyalkyl methacrylates polyacrylamides, polymethacrylamides etc: I n case of hydrophobic polymers, such as matrices based on divinyl and monovinyl- substituted benzenes, the surface of the matrix is often hydrophilized to expose hydrophilic groups as defined above to a surrounding aqueous liquid.
  • hydrophobic polymers such as matrices based on divinyl and monovinyl- substituted benzenes
  • the surface of the matrix is often hydrophilized to expose hydrophilic groups as defined above to a surrounding aqueous liquid.
  • Such polymers can be easily produced according to standard methods, see e.g., Aishady, C/iiniica e L'Industria 70(9), 70-75 ( 1988).
  • a commercially available product such as SourceTM (GE HEALTHCARE, Uppsala, Sweden) and Poros (APPLIED BIOSYSTEMS. Foster City. CA) may be used.
  • the solid support comprises a support of inorganic nature. eg..silica, zirconium oxide, titanium oxide and alloys thereof.
  • the surface of inorganic matrices is often modified to include suitable reactive groups for further reaction to SpA and its variants. Examples include CM Zirconia (Ciphergen- BioSepra (CERG YPO TOISE, France) and CPG® (MILLIPORE).
  • the solid support may, for instance, be based on zirconia, titania or silica in the form of controlled pore glass, which may be modified to either contain reactive groups and/or sustain caustic soaking, to be coupled to ligands.
  • Exemplary solid support formats include, but are not limited to, a bead (spherical or irregular), a hollow fiber, a solid liber, a pad, a gel, a membrane, a cassette, a column, a chip, a slide, a plate or a monolith.
  • a matrix in one embodiment, it is in the form of a porous monolith, which may be made using an inorganic material such as, e.g.. silica, or an organic material such as, e.g. polymethacrylale. polyacrylate, polyacrylamide, polymethacrylamidc, polytetrafluoroethylene, polysulfone, polyester, polyvinylidene fluoride, polypropylene, polyethylene, polyvinyl alcohol,
  • an inorganic material such as, e.g. silica
  • organic material such as, e.g. polymethacrylale. polyacrylate, polyacrylamide, polymethacrylamidc, polytetrafluoroethylene, polysulfone, polyester, polyvinylidene fluoride, polypropylene, polyethylene, polyvinyl alcohol,
  • polyvinylether and polycarbonate In case of a monolith, it may be formed via polymerization or by coaling a substrate.
  • the matrix is in beaded or particle form that can be porous or non-porous.
  • Particles may be spherical or non-spherical as well as magnetic or non-magnetic.
  • 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. Also, solid support in forms such as a surface, a chip, a capillar)', or a filter may be used.
  • the matrix could also be in the form of membrane in a cartridge.
  • the membrane could be in flat sheet, spiral, or hollow fiber format.
  • a ligand according to the present invention is attached to a soluble support, e.g., a soluble polymer or a water soluble polymer.
  • a soluble support e.g., a soluble polymer or a water soluble polymer.
  • soluble supports include, but are not limited to, a bio-polymer such as. e.g.. a protein or a nucleic acid.
  • bioiin maybe used as a soluble polymer, e.g., as described in US Patent Publication No. 20080108053.
  • biotin may be bound to a ligand, e.g.. a SpA-based ligand according to the present invention, which subsequent to being bound to the ligand.
  • the polymer may also be a synthetic soluble polymer, such as, for example, including but not limited, to a polymer containing negatively charged groups
  • Exemplary synthetic soluble polymers can be found i International PCI Publication No. WO2008091740 and U.S. Publication No. US20080255027, the entire teachings of each of which are incorporated by reference herein. These polymers, upon specific physical changes in one or more conditions such as pH, conductivity or temperature, can be used to purify the protein of interest via precipitation in either a reversible or an irreversible fashion. Synthetic soluble polymers may be used alone or may be coupled with a ligand according to the present invention and used for
  • a protein of interest such as, e.g., an antibody or a fragment thereof, via precipitation in either a reversible or an irreversible fashion.
  • ligands are attached to a membrane in a multi-well plate format. In yet other embodiments, the ligands are incorporated into a capillary or a microfluidics device.
  • any suitable technique may be used for attaching a ligand described herein to a support, e.g.. a solid support including those well-known in the art and described herein.
  • the ligand may be attached to a support via conventional coupling techniques utilizing, e.g. amino and/or carboxy groups present in the ligand.
  • conventional coupling techniques utilizing, e.g. amino and/or carboxy groups present in the ligand.
  • bisepoxides, epichlorohydrin. CNBr, N- hydroxysiiccinimide (NHS) etc.. are well-known coupling reagents.
  • a spacer is introduced between the support and the ligand, which improves the availability of the ligand and facilitates the chemical coupling of the ligand to the support.
  • more than one site on a ligand is attached to a solid support such (i.e., via multipoint attachment), thereby resulting in an affinity chromatography matrix which shows reduced fragmentation of the ligand upon extended caustic exposure (both in case of the free ligand as well as the attached ligand).
  • protein ligands can be coupled to a solid support via active groups on cither the surface of the solid support or the protein ligand, such as. for example, hydrolxyl, thiol, epoxide, amino, carboiiyl. epoxide, or carboxylic acid group. Attachment can be achieved using known chemistries including, but not limited to. use of cyanogen bromide (CNBr). N-hydroxyl succinimide ester, epoxy (bisoxirane) activation, and reductive animation.
  • active groups on cither the surface of the solid support or the protein ligand such as. for example, hydrolxyl, thiol, epoxide, amino, carboiiyl. epoxide, or carboxylic acid group. Attachment can be achieved using known chemistries including, but not limited to. use of cyanogen bromide (CNBr). N-hydroxyl succinimide ester, epoxy (bisoxirane) activation, and re
  • thiol-directed protein coupling has been described in the literature. See. e.g.. Ljungquist, et al. Eur. J. Biochem. Vol 186, pp. 558-561 (1 89). This technique has been previously applied for coupling SpA to a solid support. Since wild type SpA does not contain thiol groups, the attachment is achieved by reconibinantly inserting a thiol containing cysteine at the C-terminus of SpA. See, e.g.. U.S. Patent No. 6,399.750.
  • more than one site on the SpA-based chromatography ligands is attached to a sol id support via non-discriminate, multipoint attachment.
  • SpA contains abundant free amino groups from numerous lysines in each domain.
  • the attachment of a SpA domain to a solid support via multipoint attachment e.g.. a chromatography resin with epoxide or aldehyde group, can be achieved by reacting the amino group of lysine on SpA, via epoxide ring-opening or reductive animation, respectively.
  • multipoint attachment can be achieved by the reaction of one or more natural ly occurring amino acids on SpA having free hydroxy!
  • multipoint attachment can be achieved, for example, by the reaction of naturally occurring amino acids on SpA having free carboxylic acid groups, such as, for example, aspartic acid and glutamic acid, with a support containing amino groups via. for example, ⁇ '. ⁇ ' '-carbonyIdiimidazole. Multipoint attachment of the ligand to support can also be achieved by a combination of all the above mechanisms.
  • SpA-based chromatography l igands may also be attached to a solid support via an associative mechanism.
  • an associative group may interact with a ligand of interest non-covalently via ionic, hydrophobic or a combination of interactions, thereby to attach ligand of interest onto the solid surface. This faci litates the high efficiency coupling of ligand to the solid matrix, for example, as described in U.S Patent Nos. 7,833,723 and 7.846,682, incorporated by reference . herein, thereby resulting in ligand density higher than that without the associative groups.
  • Associative groups suitable for use in the invention include charged species such as ionic species, and uncharged species such as hydrophobic species.
  • the associative group may modi fy the solid support, e.g. by covalently binding directly with the solid support.
  • Suitable examples of ionic species may include quaternary amines, tertiary amines, secondary amines, primary amines, a sulfonic group, carboxylic acid, or any combination thereof.
  • Suitable examples of hydrophobic species may include a phenyl group, a butyl group, a propyl group, or any combination thereof. It is also contemplated that mixed mode species may be used.
  • the associative group may also interact with the protein ligand. Thus the interaction between the associative group and the protein ligand may be comprised of a mixture of interactions, e.g. ionic and hydrophobic species.
  • the associative group may be covalently coupled to the solid support by reacting a functional group ' on the solid support with a functional group on the associative group.
  • Suitable functional groups include, but are not limited to amines, hydroxyl, sulfhydryl, cafboxyl, imine, aldehyde, ketone . , alkene, alkyne, azo, nitrile, epoxide, cyanogens and activated carboxylic acid groups.
  • agarose beads contain hydroxyl groups which may be reacted with the epoxide functionality of a positively charged associative group, such as glycidyl trimethylammonium chloride.
  • associative groups may be coupled to the solid support provided that at least one Afunctional associative group is used.
  • associative groups may be coupled in tandem to the solid support or they may be individually coupled directly to th3 ⁇ 4 solid support.
  • the present invention provides; associative groups and/ or protein ligands which may be coupled to a solid support wV/-an intervening linker.
  • the linker may comprise at least one functional group coupled to a linkin moiety.
  • the linking moiety may comprise any molecule capable of being coupled to a functional group.
  • the linking moiety may include any of an alkyl, an alkenyl, or an alkynyl group.
  • the linking moiety may comprise a carbon chain ranging from 1 to 30 carbon atoms. In some embodiments the linker may be comprised of more than 30 carbon atoms.
  • the linking moiety may comprise at least one hetero-atom such as nitrogen, oxygen and sulfur.
  • the linking moiety may be comprised of a branched chain, an unbranched chain or a cyclic chain.
  • the linking moiety may be substituted with two or more functional groups.
  • Suitable buffers include, e.g., sodium acetate, sodium phosphate, potassium phosphate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium chloride, potassium chloride, sodium sulphate, etc. or any combination of the above, with the concentration ranging from l Om to 5M. In some embodiments, the concentration of salt ranges from 0.1 to 1 .5. .
  • Additional suitable buffers include any non-amine containing buffer such as carbonate, bicarbonate, sulfate, phosphate and acetate buffers, or a combination of the above.
  • salt concentration of the buffer wil l depend on the associative group used. Tor example, the sail concentration may be in the range of 5nM-l 00m . Where a charged species is used, the salt concentration may be at least 5nM but less than 0. 1 M, at least 5nM but less than 0.01 i , at least 5n but less than 0.001 M. In certain embodiments, the salt concentration may be 0.01 M. Where a hydrophobic species is used a high salt concentration is usually desirable. Thus the salt concentration may be greater than 0.001 M. greater than 0.01 , or greater than 0.1 .
  • the reaction when associative chemistry is used, the reaction is performed at a temperature ranging from 0°C to 99°C. In certain embodiments the reaction method is practiced at a temperature less than 60°C, less than 40°C, less than 20°C, or less than 1 °C. In some embodiments the method of the invention is practiced at a temperature of about 4°C. In other embodiments the method of the invention is practiced at a temperature of 20°C.
  • the present invention provides affinity chromatography matrices which incorporate SpA l igands based on one or more B, Z or C domains, where one or more domains include a deletion of 3 or 4 or 5 consecutive amino acids from the N-terminus, starting at position 1 or at position 2.
  • more than one site on an SpA-based ligand is attached to a chromatography matrix.
  • the present invention is based on an unexpected and surprising discovery that the ligands described herein, both in free form as well as when immobilized onto a solid support (e.g., a chromatography matrix ), exhibit reduced fragmentation following exposure to extended caustic conditions during use in purification processes. As discussed above, such fragmentation is undesirable as it leads to potentially immunogenic fragments of SpA domains ending up with the potentially therapeutic targe protein. Further the fragmentation makes the purification process more costly due to the need to use more ligand during the process.
  • a solid support e.g., a chromatography matrix
  • Fragmentation of affinity ligands can be readily detected using methods known in the art and those described herein. Such methods include, but arc not limited to, SDS-PAG E and SEC. [00132] Sodium dodecyl sul fate (SDS)- polyacrylamide gel electrophoresis
  • PAG E is commonly used for molecular weight analysis of proteins.
  • SDS is a detergent thai dissociates and unfolds proteins. The SDS binds to the polypeptides lo form complexes with fairly constant charge to mass ratios. The electi pphoretic migration rale throug a gel is therefore determined only by the size of the complexes.
  • Molecular weights are determined by simultaneously running marker proteins of known molecular weight. The gel is typical ly stained and the presence of
  • biomolecules of different molecular weights caii be visualized.
  • Size-exclusion chromatograph is. a method in which molecules in solution are separated by their size. It is usually applied to large or macromolecular complexes such as proteins and industrial polymers. Detection of di fferent molecular species is typically performed by UV-Vis or by light scattering. In the case of UV-Vis, a wavelength speci fic lor detection of certain species is chosen. The orders in which certain molecular species elute, as observed on the chromatogram, as well as the intensity of corresponding peaks, provides information, on the species type as we ' ll as relative quantity.
  • the SpA ligands according to the present invention exhibit reduced fragmentation relative to their vvt counterparts, following exposure to caustic conditions.
  • a SpA ligand having an N-terminus deletion, as described herein, and its vvt counterpart are both exposed to 0.5M NaOH for 25 hrs.
  • the solution is then neutralized with an acid to pH 7.
  • the neutralized solutions are injected into S C or loaded on to an SDS-PAG E gel for analysis and comparison.
  • an affinity chromatography matrix including a ligand having an N-terminus deletion attached to a solid support (immobilized via multipoint attachment), as described herein, as well as an affinity chromatography matrix including its vvt counterpart attached to a solid support (immobilized via multipoint attachment), are both exposed to 0.5M NaOH for 25 hrs.
  • the caustic solution and the matrix e.g.. in the form of a resin
  • the neutralized solutions are injected into SEC or loaded on to an SDS-PAGE gel for analysis and comparison.
  • the l igands described herein are also alkaline stable.
  • the alkal ine stability of the matrices containing the ligands can be assayed using standard techniques in the art and those described herein.
  • the alkaline stability of a ligand immobilized onto a matrix can be assayed using routine treatment with NaOH at a concentration of about 0.5 , e.g., as described herein as well as in U.S. Patent Publication No.
  • alkal ine stable SpA molecules as .well as matrices incorporating the same exhibit an "increased " or "'improved " alkaline stability, meaning that the molecules and matrices incorporating the same are stabl under alkaline conditions for an extended period of t ime relative to their wt counterparts.
  • chromatography matrices incorporating SpA ligands based on the wt B, C or Z domain of SpA or having a mutation of one or more asparagine residues provides an improved alkaline stabi lity under conditions where the pH is above about 10, such as up to about 1 3 or 14.
  • ligands according to the present invention as well as matrices incorporating the same are no more al kal ine stable than their wt counterparts; nonetheless, they exhibit reduced fragmentation.
  • One such ligand described herein is a penlameric form of the C domain ligand including an N-terniinus deletion in each of the domains and including a G29 mutation in each of the domains.
  • Such a ligand may further include an alanine as the very first amino acid in the pentamer to facilitate homogenous post-translational processing.
  • the present invention is based on the surprising and unexpected discovery of novel SpA ligands (in both free form as well as well when immobilized into a chromatography matrix) which exhibit reduced fragmentation during use in purificalion processes relalive to some of the previously described ligands, in addition to retaining at least 95% of the initial binding capacity following extended exposure to caustic conditions (e.g., 0. 1 M NaOH for 25 hours or more).
  • more than one site on the ligands is attached onto a solid support and these ligands are based on B. C. or Z domains of SpA. where the ligands have a deletion of 3, 4 or 5 consecutive amino acids from the -terminus, starting at position I or at position 2.
  • the percentage of retained binding capacity of the SpA ligands described herein (e.g.. those comprising one or more B, C or Z domains, and any combinations thereof, where at least one of B, C or Z domain includes a deletion of at least 3 consecutive amino acids from the N-terminus). is at least 1 .25 times more, 1 .5 times more. 2.0 times more, 2.5 times more, or 3 times more than that of the wt counterpart.
  • the alkaline stability of the immobilized ligand, as assayed by the retention of IgG binding capacity over time, is measured as follows.
  • the binding capacity, referred to as Qd 50% is measured by obtaining the volume of IgG loaded to a concentration based on absorbance at UVseomn of 50% of the initial IgG concentration.
  • the initial Qd 50% of the chromatography matrix e.g., resin packed in a column
  • the chromatography matrix e.g.. resin as described above
  • Qd 50% is measured again.
  • caustic or alkaline stability of the matrix is measured by static soaking of the matrix.
  • an affinity chromatography matrix e.g.. in resin format
  • IgG binding capacity e.g. 1 M NaOH, 0.3N NaOH or 0.5M NaOH for 25 his with gentle rotation and measuring IgG binding capacity before and after the NaOH soaking
  • the alkaline stability by way of retention of binding capacity of the matrix for IgG. can be determined.
  • the present invention provides a method of puri fying a target molecule from a mixture using the affinity chromatography matrices described herein.
  • the target molecule may be any molecule which is recognized by an affinity ligand provided herein, where the ligand is coupled to a sol id support ⁇ i.e., a chromatography matrix).
  • target molecules include immunoglobulins and Fc-containing proteins.
  • the immunoglobul ins may be polyclonal antibodies or a monoclonal antibody or a functional fragment thereof.
  • Functional fragments include any fragment of an immunoglobulin comprising a variable region that still binds speci fical ly to its antigen while at the same time retaining its abil ity to speci fically bind to a protein ligand coupled to a sol id support.
  • a method of isolating a target molecule of interest using an affinity chromatography matrix described herein includes the steps of: (a) contacting a solid support including an immobilized SpA-based
  • chromatography ligand having an amino acid sequence selected from the group consisting of SEQ I D NOs: 13-42, SEQ ID NOs: 55-84 and SEQ ID NOs: 93-95, with a mixture comprising a target molecule under conditions such that the target molecule speci fically binds to the ligand; and (b) altering the conditions such that the target molecule is no longer bound to the ligand. thereby isolating the target molecule.
  • the altering step includes altering the pH, such the target molecule is no longer bound to the l igand.
  • the pi t is altered in a manner such that it is more acidic than the pH conditions in step (a).
  • step (a) may be performed at a neutral pl-1, or a pl-l ranging from about 6 to about 8 and step (b) may be performed at an acidic pH, e.g.. a pl-1 ranging from about 1 to about 5.
  • step (b) comprises altering the salt concentration of the buffer in use, such that the target molecule is no longer bound to the l igand.
  • a high salt concentration e.g., > 0. 1 M.
  • a lower salt concentration e.g.. ⁇ 0. I M
  • a low salt concentration e.g., ⁇ 0.1 M
  • both the pl-1 and the salt concentration of the buffer may be altered between step (a) and step (b).
  • the ligands described herein can be used in any puri fication process or a purification process train where native SpA and recombinant SpA are typical ly used. I n other words, it is generally desirable to replace the native SpA (e.g., isolated from S. aureus) and recombinant SpA ⁇ e.g.. recombinantly expressed w r t SpA) in the current processes in the art with the ligands described herein, in order to reduce overall cost as well as mitigate the risk of potential ly immunogenic SpA fragments co-purifying with a potential therapeutic molecule.
  • native SpA e.g., isolated from S. aureus
  • recombinant SpA e.g.. recombinantly expressed w r t SpA
  • the present invention relates to a method of purification of antibodies by affinity chromatography, where the method includes the following steps: contacting a process feed with an affinity chromatography matrix according to the invention in order to bind one or more antibodies in the feed; an optional wash step; adding a suitable elution buffer for releasing the bound antibodies from the matrix; and recovering the one or more antibodies from the eluaie.
  • the affinity chromatography matrices described herein may also be used lor isolating antibodies from culture liquids, supernatants as well as fermentation broths. In case of fermentation broths, the use of affinity chromatography matrices enables the separation of antibodies from host cell proteins (HCPs), DNA. viruses, endotoxins, nutrients, one or more components of a cell culture medium, e.g.. antifoam agents and antibiotics, and product-related impurities, such as misfolded species and aggregates.
  • HCPs host cell proteins
  • the feed is subjected to mechanical filtration before it is contacted with the affinity chromatography matrix described herein, and consequently the mobile phase is a clari fied cel l culture broth.
  • Suitable conditions for adsorption are well known to those of skil l in the art.
  • the present invention relates to a multi-step process for the purification of antibodies, which process comprises a capture step using an affinity chromatography matrix described herein followed by one or more subsequent steps for intermediate purification and/or polishing of the antibodies.
  • the capture step is followed by hydrophobic interaction and/or ion exchange chromatography and/or weak partition chromatography in bind-and elute or flow through mode.
  • the capture step is followed by multimodal anion or cation exchange chromatography and/or weak partition chromatography in bind-and-elute or flow through mode.
  • any leached SpA-based ligand from the affinity chromatography matrix can be removed by the subsequent purification steps to acceptable levels e.g.. to levels deemed acceptable for native Protein A ligand.
  • ligands described herein may be used in any process which typically employs Protein A ligands.
  • Example 1 Generation of SnA Ligands With One or More Domains Having an
  • DNA 2.0 ( enlo Park, CA).
  • a SpA dimeric protein containing two Z domains, each domain containing the mutation at position 29 (A29K) to reduce or eliminate Fab binding (amino acid sequence shown in SEQ ID NO: 85): and a SpA dimeric protein containing two Z domains, each domain containing the A29 mutation and the second Z domain containing a deletion to delete 4 consecutive amino acids from the N-terminus (amino acid sequence shown in SEQ ID NQ:78).
  • each synthetic gene includes a codon for an initialing methionine and the ?r end includes six histidine codons (SEQ I ' D NO:86) for subsequent purification using NiNTA column.
  • the 5 ! and 3 ' ends of each gene contain Ndel and BamHI restriction sites, respectively.
  • These synthetic genes as well as the expression vector that is used, Le., pETI l a.(EMD). are digested with Ndel and BamHI (NEW ENGLAND BIOLABS, Ipswich, MA), the DNA fragments are separated on a 0.7 % agarose TAE gel and the appropriate DNA fragments are excised and purified using the gel extraction kit from QI AGEN (Valencia, CA).
  • the purified inserts are ligated into the backbone of a pETI l a or any other suitable expression vector using T4 DNA ligase (NEW ENGLAND BIOLABS, Ipswich, MA).
  • T4 DNA ligase N4 DNA ligase
  • dimeric SpA ligand constructs containing C domains are also generated.
  • a dimeric construct expressing a C domain ligand is generated, the amino acid sequence of which is set forth in SEQ ID NO:92; as well as a dimeric construct expressing a 2 C domain ligand is generated, where only the second C domain includes a deletion of 4 consecutive amino acids from the N-terminus, the amino acid sequence of which is set forth in SEQ I D NO:35.
  • These C domain dimeric ligands do not have a mutation at position 29.
  • any suitable bacterial expression system can be used for expressing the various SpA l igands described herein.
  • the protein may be expressed in an Esc erchia coli strain such as strain BL21 (DE3) (PRO MEG A, Madison Wl) using a pET vector such as pETl l a (EMD).
  • a single colony is selected from a plate and grown overnight at 37°C in LB media containing 1 00 ng/mL ampicil lin.
  • the overnight culture is di luted 1 00- fold into fresh LB media containing 1 00 g/mL ampicil l in and grown to a cell density such that the optical density at 600 nm is ⁇ 0.8.
  • I mM isopropyl-beia-D-thiogalactopyraiioside cells are grown for an additional two hours. Expression is confirmed by SDS-PAGE analysis and Western blotting.
  • HEALT HCARE is crosslinked using epichlorohydrin according to a previously described method (Porath and Fornstecll, ./. Chromatography., 51 :479 ( 1979)).
  • the agarose resin is subsequently reacted with positively charged associative groups, e.g., cations, according to the following method: to 10 mL of resin. 5 mL of 75 % wt glycidyl trimeihylammonium chloride (GTMAC), 5 mL Milli-Q ⁇ water
  • the filtered bead cake ( 10 niL) is added to a jar containing a 10 mL solut ion comprised of 1 mL of ihioglycerol and 9 niL of a buffer sol ution with 0.2M NaHCOj and 0.5M NaCl.
  • the mixture is slurried and rotated overnight at room temperature.
  • the resin is then washed with 3 times with 10 m L of the followin buffers: O. l M Tris buffer with 0. 1 5M NaCl (pH 8) and 50mM acetic acid (pl l 4.5).
  • SEC size exclusion chromatography
  • I niL of 1 NaOI I is added to a final concentration of 0.5M NaOI I and 0.5 mg/mL ligand.
  • the sample is gently rotated for 25 hrs. This solution is then neutralized to pH ⁇ 7 using 32 pL of glacial acet ic acid.
  • the dimeric C domain ligand having no deletions shows the presence of a . smear as well as smaller fragments around 7 KDa on an SDS-PAGE following caustic soak in 0.5M NaOH for 25 hours (see Lane 9) relative to the dimeric C domain construct which includes a deletion of 4 consecutive amino acid deletion from the N-terminus of the second domain, the amino acid sequence of which is set forth in SEQ ID NO:35 (see Lane 12).
  • Each of the dimeric Z and C domain ligands additionally includes a
  • Lane 2 (dimeric Z domain control), Lane 5 (dimeric Z domain ligand having a N-terminus deletion). Lane 8 (dimeric C domain control) and Lane 9 (dimeric C domain ligand having a N-lerminus deletion).
  • the dimeric Z and C domain ligands having the N-terminus deletions in the second domain show reduced fragmentation, as identified by boxes on the chromatogram in Figure 4.
  • Lanes 8- 10 depict the fragmentation observed with a recombinant
  • rSPA SpA ligand
  • the rSPA ligand appear to show an even far greater degree of Iragmcntation following caustic soak in 0.5M NaOH for 25 hours relative to the Z domain control, as observed by a near disappearance of the protein on the SDS-PAGE (see Lane 9).
  • the rSPA ligand not exposed to caustic conditions is in Lane 8.
  • the pentameric form of the Z domain control (SEQ ID NO: 1) with no amino acid deletion shows well resolved peaks at lower molecular weight, indicating the presence of smaller fragments.
  • the pentameric form of the Z domain having the N-terminus deletion shows significantly fewer distinct peaks at lower intensity, indicating a far less degree of fragmentation, relati ve to the control.
  • chromatography column (EVERGREEN SCIENTIFIC. Los Angeles. CA) is measured using Milli-Q® water.
  • the resin is conditioned in a column with 2 CV (2 mL) of 0.5M NaOH quickly, re-si urried and vacuumed. After repeating the NaOH condition one more time, the vacuumed wet cake of resin is transferred to 4 mL test tubes (THERMOFISHER, Waitham, MA). 2 mL of 0.5M NaOH is added to the column (bottom is capped) and immediately transferred into the test tube with the corresponding resin. Place capped test tubes onto a rotator and rotate the test tubes for 25 hrs.
  • the affinity chromatography matrices i.e.. resins having the immobilized resins thereon w / multipoint attachment
  • the affinity chromatography matrices are further tested for their static binding capacity before and after exposure to 0.5M NaOH for 25 hours.
  • each of the chromatography matrices in 1 mL volume) immobilized with the dimeric or pentameric 2 or C domain ligands described above, either with exposure to 0. 1 , 0.3 or 0.5M NaOH or without exposure to NaOH, is made into 10% slurry in ivlilli-Q® water (Ml LLIPORE, Billerica. MA).
  • Table HI shows the percentage of retained IgG binding capacity of a matrix having immobilized thereon a pentameric form of Z domain ligand which contains an A29K mutation and all but the first domain include a deletion of four consecutive amino acids from the N-terminus (amino acid sequence shown in SEQ ID NO: 84), after soaking the matrix in 0.1 M NaOH, 0.3 M NaOH or Q.5M NaOH.
  • the matrix with the pentameric Z domain N-terminus deletion iigand shows up lo 95% of the initial binding capacity after 0.1 NaOH soak for 25 hours; up to 85% of the initial binding capacity after 0.3. NaOH soak for 25 hours and up to 65% of the initial binding capacity a ter 0.5M NaOH soak for 25 hours.
  • Resin samples immobilized with rSPA (REPUGEN Waltham, MA), and the Z domain peniameric ligand (amino acid sequence shown in SEQ ID 0.84). are each packed into a chromatography column with 1 cm diameter and 5 cm packed bed height. After equilibration with phosphate saline buffer ( " 1 OmM sodium phosphate)., the packed resins are subjected to exposure of null CHO feed with polyclonal hlgG (SERACARE, 5 mg/mL) at a flow rate of 50 cm/hr. After loading at 90 % of 5 % breakthrough, the resin is washed with PBS buffer and 50mM NaOAc, pH 5.5.
  • the bound IgG is subsequently eluted with 50mM NaOAc, pl l 3. Fractions are collected and analyzed for impurity analysis. The packed resin is then exposed to 0.5M NaOH for 15 minutes (flow rale 100 cm/hr) before contacting again with polyclonal hlgG in null CHO feed. Resins are then washed with PBS buffer and 50mM NaOAc, pM 5.5 and IgG is eluted for further assay.
  • [00204J Fractogel S0 3 " (M I LLIPORE, Billerica, MA) is packed into a column with bed dimension of 1 .0 cm (i.d.) x 7 cm (bed height).
  • the column is equil ibrated with 50mM NaOAc pH 4.5, 4 mS/cm and loaded with the pooled IgG from Protein A elution at 140 cm/hr.
  • IgG is eluted with 0.5N NaCI in 50mM NaOAc over 20 column volume (linear gradient).
  • the elution pools are collected in 10 mL fractions and analyzed for leached ligands, DNA, and host cell protein.
  • each of the control ligand (SIEQ ID NO:85), the ligand with only the first amino acid deleted from the N-terminus of the second domain (SEQ ID NO:87). and the ligand with the first two amino acids deleted from the N-terminus of the second domain (SEQ ID NO:88) shows fragments at lower molecular weight, as depicted by the arrows, evidencing fragmentation.
  • the ligand with the first three amino acids deleted from the N-terminus of the second domain (SEQ I D NO:69) and the ligand with the first four amino acids deleted from the N-terminus of the second domain (SEQ ID NO:78) showed significantly reduced fragmentation at lower molecular weight as depicted by boxes in the chromatogram. evidencing a reduced fragmentation.
  • affinity ligands based on one or more domains of Protein A and having at least 3 amino acids deleted from the N-terminus of one or more domains exhibit reduced fragmentation following extended caustic exposure and accordingly, are superior candidates for use as affinity chromatography ligands.
  • Example 12 Retained Binding Capacity Comparison of N-terminus Deletion and Wild Type C domain pentamcrs, both having a non-Fab mutation (G29K)
  • the ligands are immobilized onto polyvinyl alcohol based affinity chromatography resins via multipoint attachment (see, e.g., 1-lermanson el al., Immobilized Affinity Ligand Techniques, Academic Press, pp. 5 1 - 1 36 ( 1 92)), and tested tor retained dynamic binding capacity upon repeated NaOH exposure.
  • the chromatography matrices are packed into col umns (0.66 cm i.d. x 1 .0 cm bed height) and are subjected to a standard chromatographic run with equilibration fol lowed by application of 30 mg polyclonal human IgG (hlgG) at 60 cni/hr. After extensive washing-out of unbound proteins with equilibration buffer ( l Om phosphate buffer saline), bound IgG is eluted with ante buffer (0.1 M citric acid, pH 3) at 60 cm/hr. This is followed by Cleaning-In- Place (CI P) with 0.7 NaOH for 30 mins.
  • equilibration buffer l Om phosphate buffer saline

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Abstract

The present invention relates to chromatography matrices including ligands based on one or more domains of imnumoglobulin-binding proteins such as. Siaphylococcns aureus Protein A (SpA); as well as methods of using the same.

Description

CH ROMATOGRAPHY MATRICES INCLUDING NOVEL
STAPH YLOCOCCUS AUREUS PRO EIN A BASED LIGANDS
Related Applications
[0001 ] The present application claims the benefit of priority of U.S.
Provisional Patent Application No. 61 /494,701 , filing date June 8. 201 1 , incorporated by reference herein in its entirely.
Field of the Invention
[0002] The present invention relates to chromatography matrices including ligands based on one or more domains of immunoglobulin-binding proteins such as, Staphylococcus aureus Protein A (SpA) as well as methods of using the same.
Background
[0003] Ligands used in affinity chromatography typically confer a high selectivity for the target molecule, thereby resulting in high yield,, high purity and fast and economical purification of target molecules. Staphylococcus aureus Protein A- based reagents and chromatography matrices have found a widespread use in the field of affinity chromatography for capture and purification of antibodies and Fc- containing proteins as well as in analytical-scale antibody detection methods due to its ability to bind IgG, without significantly affecting the affinity of the immunoglobulin for antigen.
[0004] Accordingly, various reagents and media comprising Protein A- ligands have been developed and are commercially available, for example, ProSep®- vA High Capacity, ProSep® vA Ultra and ProSep® UltraPlus (MILLIPORE) and Protein A Sepharose™, MabSelect™, MabSelect Xtra™, MabSelect SuRe™ (GE HEALTHCARE), MabSelect SuRe™ LX and Poros MabCapture A™ (LIFE TECHNOLOGIES).
[0005] In order to maintain selectivity of the chromatography ligands including ligand bound solid supports such as SpA bound chromatography matrices, matrices have to be cleaned and are typically cleaned under acidic or alkaline conditions, e.g.. with sodium hydroxide (NaOH). For example, a standard process which is used for cleaning and restoring the matrix is a eleaning-iii-place (CIP) alkaline protocol, which typically involves treatment of the ligand bound matrix with NaOH concentration ranging from 0.05M to I , resulting in pl l range 1 2.7 to 14.0.
Typically, exposure of an affinity chromatography matrix to repeated CI P cycles results in significant loss of binding capacity of the matrix for a target molecule over time, requiring the use of a.greater amount throughout the process, of often very expensive ligands which are bound to matrices. This is both uneconomical and undesirable as it results in the purification process becoming more expensive as wel l as lengthy.
Sum man' of the I vention
[0006] Protein A based chromatography matrices have been previously described in the art which appear to show a reduced loss of binding capacity for a target molecule following treatment with alkaline conditions. See. e.g.. U.S. Patent Publication No. 20100221 844. which describes affinity chromatography matrices incorporating wild-type (wt) B or Z domains of SpA with multiple point attachment to the matrix, which show up to 95% of the initial binding capacity even after exposure to 0.5'M NaOH for 5 hours or more. Also, U.S. Patent Publication No. 20100048876 describes a chromatography matrix incorporating wild type C domain of SpA as well as a C domain containing a deletion of amino acid residues 3 through 6, which appear to show up to 95% of the initial binding capacity after exposure to 0.5M for about 5 hours. These ligands are immobilized via a cysteine directed single-point attachment to the matrix. Further, chromatography matrices have been described which
incorporate Protein A domains containing mutations at one or more asparagine residues of the protein, where the matrices appear to show a reduced . loss in binding capacity relative to the wi ld type SpA, fol lowing exposure to alkaline conditions and appear to be immobilized via a single-point attachment to the matrix. See, e.g.. U.S. Patent No. 6,8 1 , 161 .
[0007] Although, the aforementioned affinity chromatograph matrices appear to show a reduced loss in binding capacity for a target molecule following exposure to caustic conditions, some of these matrices appear to show a large degree of fragmentation of l igand, e.g., as observed using SDS-PAGE and/or size exclusion chromatography (SEC), following exposure to caustic conditions. Such fragmentation is undesirable, as a large degree of fragmentation of ligand results in smaller fragments of ligands being present which are more difficult to remove and separate from the target molecule, thereby increasin the likelihood that such potentially immunogenic fragments will co-purify with the therapeutic target molecule. Furthermore, a large degree of fragmentation results in an increased loss in binding capacity of the matrix for a target molecule.
[0008] The present invention provides affinity chromatography ligands and matrices incorporating the same, where the ligands are based on one or more
Staphylococcus aureu Protein A (SpA) domains having a deletion from the -terminus, starting at posit ion 1 or position 2 of the domain. These ligands and matrices show reduced fragmentation during purification use, as evidenced by SDS-PAGE and/or SEG teehniciues. relative to some of the previously described ligands, thereby making them more attractive and economical candidates for use in affinity chromatography.
[0009] In one aspect according to the present invention, affinity chromatography matrices are provided, which includes one or more B domains of SpA having a deletion, one or more C domains of SpA having a deletion or one or more Z domains of SpA having, a deletion, where the one or more domains are attached to a solid support.
[0010] In one embodiment, an affinity chromatography matrix according to the present invention includes a ligand attached to a solid support, vvhere the ligand comprises one or more B domains of Staphylococcus aureus Protein A (SpA), where at least one B domain comprises a deletion of at least 3 consecutive amino acids from the - In another embodiment, an affinity chromatography matrix according to the present invention comprises a ligand attached to a solid support, where the ligand comprises one or more C domains of Staphylococcus aureus Protein A (SpA). -where at least one G domain comprises a deletion of at least 3 consecuti ve amino acids from the N-termirius.
[001 11 in yet another embodiment, an affinity chromatography matrix according to the present invention comprises a ligand attached to a solid support, where the ligand comprises one or more 2 domains of Staphylococcus aureus rotein. A,.(SpA), where at least one Z domain comprises a deletion of at least 3 consecutive amino acids from the - lerminus.
[0012] In still other embodiments, an affinity chromatography matrix according to the present invention comprises a ligand attached to a solid support, where the ligand comprises t\vo or more B domains, two or more C domains or two or more Z domains, or any combination of B, C and Z domains, where at least one of B, C or Z domain comprises a deletion of at least 3 consecuti ve amino acids from the N-terminus. [001 J In various embodiments according to the present invention, more than one site on each ligand is attached to a solid support (i.e.. multipoint attachment).
(00141 In various embodiments according to the present invention, the ligand exhibits reduced fragmentation, as determined by SDS-PAGE or by size-exclusion chromatography (SEC), relative to its wt counterpart, following exposure of the ligand or the matrix containing the ligand to 0.5M NaOH for at least 5 hours.
[00151 In some embodiments according to the present invention, the ligand comprises a deletion of 3 amino acids from the N-terminus, a deletion of 4 amino acids from the N-terminus or a deletion of 5 amino acids from the N-terminus, where more than one site on the ligand is attached to a solid support, thereby to form an affinity
chromatography matrix.
[0016] In a particular embodiment, a ligand has an amino acid sec)iience set forth in any of SEQ ID NOs: 13-42, SEQ ID NOs:55-84 and SEQ ID NOs: 93-94.
[0017] In another embodiment, a ligand according to the present invention has the following structure: |(X)„, (Y)m]n+m. where X represents a B domain, a Z domain or a C domain of SpA, n represents the number of domains ranging from zero through (m-1 ), Y represents a B domain or a Z domain or a C domain of SpA having at least 3 consecutive amino acids deleted from the N-terminus and m represents the number of Y domains ranging from one through eight, where more than one site on the ligand is attached to a solid support (e.g., a chromatography matrix).
[0018] In some embodiments according to the present invention, the ligand comprises two B domains or two Z domains or two C domains of SpA, or one B and one C domain, or one B and one Z domain, or one C and one Z domain, where at least one B domain or at least one Z domain or at least one C domain includes a deletion of three consecutive amino acids from the N-terminus or a deletion of four consecutive amino acids from the N-terminus or a deletion of five consecutive amino acids from the N-terminus. It is understood that the various domains may be arranged in any order.
[0019] In another embodiment, a ligand according to the present invention comprises three B domains or three Z domains or three C domains, or any combination of B, C or Z domains in any order, where at least one B domain or at least one Z domain or at least one C domain comprises a deletion of three consecutive amino acids from the N- terminus or a deletion of four consecutive amino acids from the N-terminus or a deletion of five consecutive amino acids from the N-terminus. [0020] in yet another embodiment, a ligand according to the present invention comprises four B domains or lour Z domains or four C domains, or any combination of B. Z or C domains in any order, where at least one B domain or at least one Z domain or at least one C domain comprises a deletion of three consecutive amino acids from the N- terminus or a deletion of four consecutive amino acids from the N-terminus or a deletion of live consecutive amino acids from the N-terminus.
[0021 ] In yet another embodiment, a ligand according to the present invention comprises ive B domains or five Z domains or five C domains, or any combination of B, Z or C domains in any order, where at least one B domain or at least one Z domain or at least one C domain comprises a deletion of three consecutive amino acids from the N-terminus or a deletion of four consecutive amino acids from the N-terminus or a deletion of five consecutive amino acids from the N-terminus.
[0022] In yet another embodiment, a l igand according to the present invention comprises six B domains or six Z domains or six C domains, or any combination of B, Z or C domai ns in any order, where at least one B domain or at least one Z domain or at least one C domain comprises a deletion of three consecuti ve amino acids from the N-terminus or a deletion of four consecutive amino acids from the N-terminus or a deletion of five consecutive amino acids from the N-terminus.
[0023] I n yet another embodiment, a ligand according to the present invention comprises seven B domains or seven Z domains or seven C domains, or any combination of B; Z or C domains in any order, where at least one B domain or at least one Z domain or at least one C domain comprises a deletion of three consecutive amino acids from the N- terminus or a deletion of four consecutive amino acids from the N-terminus or a deletion of live consecutive amino acids from the N-terminus.
[0024] In a further embodiment, a ligand according to the present invention comprises eight B domains or eight Z domains or eight C domains, or any combination of B, Z or C domains in any order, where at least one B domain or at least one Z domain or at least one C domain comprises a deletion of three consecutive amino acids from the N- terminus or a deletion of four consecutive amino acids from the N-terminus or a deletion of five consecutive amino acids from the N-terminus.
[0025] Additional ly, provided herein are methods of usi ng the affinity chromatography matrices . Accordingly, a method of affinity puri fying one or more target molecules (e.g., immunoglobulins or Fc -containing proteins) from a sample is provided, where the method comprises the steps of: (a) providing a sample comprising one or more target molecules (e.g., immunoglobulins or Fc-containing proteins); (b) contacting the sample with a matrix according to the invention under conditions such that the one or more target molecules (e.g.. immunoglobulins or Fc-containin proteins) bind to the matrix; and (c) recovering the one or more bound target molecules (e.g.. immunoglobulins or Fc- containing proteins) by eluting under suitable conditions such as. for example, a suitable pH.
[0026] In some embodiments, an affinity chromatography matrix according to the present invention retains at least 95% of its initial binding capacity for a target molecule after 5 hours, or after 10 hours, or after 15 hours, or after 20 hours, or after 25 hours, or after 30 hours of incubation in 0.5 M NaOH.
[0027] In a particular embodiment, an affinity chromatography matrix according to the present invention retains at least 95% of its initial binding capacity after 5 hours incubation in 0.5M NaOH.
[0028] In yet another embodiment., an affinity chromatography matrix according to the present invention retains at least 95% of its initial binding capacit for a target molecule after 25 hours incubation in 0, 1 NaOH; at least 85% of its initial binding capacity for a target molecule after 25 hours incubation in 0.3M NaOH; or at least 65% of its initial binding capacity for a target molecule after 25 hours incubation in 0.5M NaOH.
[0029] The immunoglobulins which are capable of being bound by the various ligands described herein include., e.g., IgG. IgA and IgM, or any. fusion protein comprising an antibody and any fragment of antibody, which is capable of binding to SpA.
[0030] Also provided herein are nucleic acid molecules encoding the various ligands described herein, as well as host cells including such nucleic acid molecules. In some embodiments, a host cell is a prokaryotic cell. In other embodiments, a host cell is a eukaryotic cell.
[0031] In some embodiments, the present invention provides SpA-based affinity chromatography matrices which exhibit altered (increased or decreased) binding to a Fab portion of an immunoglobulin compared to the wt SpA ligands, while retaining the ability to bind the Fc portion of the immunoglobulin. In one embodiment, an SpA-based matrix according to the present invention exhibits a decreased binding to a Fab portion of an immunoglobulin compared to wt SpA. In a particular embodiment, a chromatography matrix incorporates a SpA ligand. which includes a lysine at position 29. instead of a glycine (in Case of B and C domains of SpA) or instead of an alanine (in case of the Z domain of SpA).
Brief Description of the Drawings
[0032] FIG. 1 depicts the amino-acid sequence alignments for the wild type
(wt) IgG binding domains of SpA as well as the 2 domain, represented by SEQ ID NOs: l-6.
[0033] FIG. 2 depicts schematic diagrams of the plasmid ETl 1 a containing the nucleic acid sequence encoding the dimeric Z domain ligand with a A29K mutation, the amino acid sequence shown in SEQ ID NO:85 (control), and plasmid pETl l a containing the nucleic acid sequence encoding the dimeric Z domain ligand with a A29K mutation as well as the second domain including a deletion of 4 consecutive amino acids from the N-terminus, the amino acid sequence shown in SEQ ID NO: 78. The ligand constructs further include a His-tag sequence at the 3' end.
[0034] Figure 3 is a Copmassie stained SDS-PAGE gel fo analyzing the fragmentation pattern of free and immobilized dimeric Z and C ligands with or without caustic soak in 0.5M NaOH for 25 hrs. The description of the, various Lanes of the SDS-PAGE gel is as follows. Lane I : molecular marker: Lane 2: dimeric Z domain ligand with no caustic exposure (A29K with no deletions, shown in SEQ ID NQ:85, which is used as the control and includes a His-tag): Lane 3: the dimeric Z domain ligand control subjected to 0.5M NaOH soak for 25 hours; Lane 4: the dimeric Z domain ligand control immobilized onto an agarose chromatography resin, which is subjected to 0.5.M NaOH.' soak for 25 hours; Lane ,5: the dimeric Z domain ligand having a deletion of 4 consecutive amino acids from the N-terminus of the second domain (A29K. with the second domain having a deletion, shown in SEQ ID NO:78 and a His-tag) wilh.no caustic exposure; Lane 6: the dimeric Z domain ligand of' SEQ ID NO:78 with a His-tag subjected to 0.5M NaOH soak for 25 hours; Lane 7: the dimeric Z domain ligand of SEQ ID NQ:78 with a His-tag immobilized onto an agarose chromatography resin and subjected to 0.5 M NaOH soak for 25 hours; Lane 8: dimeric C domain ligand with no deletions used as a control (amino acid sequence shown in SEQ ID NO:92 plus having a His-tag) With no caustic exposure: Lane 9: the dimeric C domain ligand control subjected to 0.5M NaOH soak for 25 hours; Lane 10: the dimeric C domain ligand immobilized onto an agarose, chromatography resin and subjected to 0.5M NaOH soak for 25 hours: Lane 1 1 : dimeric C domain ligand having a deletion from the N-terminus of the second domain (amino acid sequence shown in SEQ ID NO:35 plus having a His-tag); Lane 12: dimeric C domain ligand of SEQ ID NO:35 plus a His-tag subjected to 0.5M NaOH soak for 25 hours; and Lane 1 3: dimeric C ligand of SEQ ID NO:35 plus a His-tag immobilized onto an agarose chromatography resin and subjected to 0.5 NaOI-I soak for 25 hours.
[0035 J Figure 4 is a chromatogram of an SEC analysis of the dimeric Z and
C ligands summarized in the description of Figure 3 above. The .v-axis denotes the rentenlion time in minutes with smaller molecules having longer retention time than that of a larger molecule. The v-axis represents UV absorption at 280 nm in niAU. The evidence of reduced fragmentation for the dimeric Z and C domain ligands having a N-terminus deletion in the second domain, following extended caustic soak (i.e., 0.5M NaOH soak for 25 hours), is shown by way of boxes on the chromatogram and the presence of smaller fragments for the dimeric Z and C domain controls is shown by way of arrows.
[0Q36] Figure 5 is a Coomassie stained SDS-PAGE gel for analyzing the fragmentation pattern of both free and immobilized pentameric Z domain ligands .with or without caustic soak in 0.5 NaOH for 25 hours. The description of the various lanes of the SDS-PAGE gel is as follows: Lane 1 : molecular weight marker; Lane 2: pentameric Z domain ligand having the A29 mutation and a deletion of 4 consecuti ve amino acids from the N-terminus of all but the first domain, the amino acid sequence of which is set forth in SEQ ID NO:84. with no caustic exposure; Lane 3: pentameric Z domain ligand of SEQ ID NO:84 subjected to 0.5M NaOH soak for 25 hours; Lane 4: pentameric Z domain ligand of SEQ ID NO:84 immobilized onto an agarose chromatography resin and subjected to 0.5 NaOH soak for 25. hours; Lane 5: pentameric Z domain ligand of SEQ ID NO:91 . used as a control, which is not subjected to caustic soak: Lane 6: pentameric Z domain ligand control subjected to 0.5N NaOH soak for 25 hours; and Lane 7: pentameric Z domain ligand control immobilized onto an agarose chromatography resin and subjected to 0.5M NaOH soak for 25 hours. Further, Lanes 8, 9 and 10 relate to the results seen with subjecting rSPA to a similar treatment, where Lane 8 represents rSPA which is not subjected to any caustic soak; Lane 9 represents rSPA subjected to 0.5M NaOH soak for 25 hours and immobilized rSPA subjected to 0.5M NaOH soak for 25 hours. The bands represent the fragmentation, as depicted by arrows. [0037] Figure 6 is a chromatogram of an SEC analysis of the pentameric Z domain ligands summarized in the description of Figure 5 above. The x-axis denotes the rentention time in minutes with smaller molecules having longer retention time than that of a larger molecule. The v-axis represents LTV absorption at 280 nm in mAU. The evidence for reduced fragmentation in case of the pentameric Z domain ligands having a N-terminal deletion in all but the first domain, following extended caustic soak, is shown by way of boxes on the chromatogram and the presence of smaller fragments seen with the pentameric Z domain control is shown by way of an arrow pointing to the fragments. Further, extensive amount of fragmentation seen for rSPA can be also observed using SEC.
[0038] Figure, 7 is a chromatogram of an SEC analysis of the immobilized pentameric Z domain ligands summarized in the description of Figure 5 above. The -axis denotes the rentention time in minutes with smaller molecules having longer retention time than that of a larger molecule. The y-axis represents U V absorption at 280 nm in mAU'. T he evidence for reduced fragmentation in case of the immobilized pentameric Z domain ligand having an N-terminal deletion in the second domain, following extended caustic soak, is shown by way of a box on the chromatogram and the presence of smaller fragments seen with the pentameric Z domain control is shown by way of an arrow pointing to the fragments. Further, extensive amount of fragmentation seen for immobilized rSPA can be also observed using SEC.
[0039] Figure 8 is a chromatogram of an S EC analysis of the free dimeric Z domain ligands following extended caustic soak, where the ligands include a N- terminus deletion of the first one (SEQ ID NO:87). first t wo (SEQ I D O:SS), first three (SEQ ID NO:69) or first four (SEQ ID NO:78) of the second domain of the dimeric ligands. The x-axis denotes the rentention time in minutes with smaller molecules having longer retent ion time than that of a larger molecule. The y-axis represents UV absorption at 280 nm in mAU. The evidence for reduced
fragmentation in case of the dimeric ligands having first three or first four amino acids deleted from the .N -terminus of the second domain following extended caustic soak is depicted by boxes. The presence of fragmentation observed following extended caustic soak of the dimeric ligands having no amino acid deletions (SEQ ID NO:85) or the first amino acid deleted or the first two amino acids deleted from the N- terminus of the second domain, is shown by way of arrows pointing to the presence of fragments on the chromatogram. [0040] Figure 9 compares the retained binding capacities of immobilized C domain pentameric ligands after repeated caustic exposure, where one pentameric ligand includes an N terminus deletion of 4 amino acids in each domain, the G29K mutation in each domain as well as an alanine as the very first amino acid in the pentamer (the amino acid sequence shown in SEQ ID NO:93): and the other pentameric ligand being its wt counterpart with the G29 K mutation (the amino acid sequence of which is shown in SEQ ID O:95). The .v-axis represents time of cumulative exposure of the chromatography matrices to 0.7 NaOH over 16 cycles of 30 mins each. The j'-axis represents the percent retained binding capacity.
Detailed Description of the Invention
[0041 ] The present invention provides affinity chromatography matrices which incorporate ligands based on one or more domains of SpA, where the ligands, either alone or when immobilized onto a matrix, show reduced fragmentation during use in puri ication processes, relative to the corresponding wt domains of SpA.
[0042] Previously described exemplar)' SpA-based chromatography ligands include, for example, those described in U.S. Patent Publication No. 20100221844. which describes chromatography matrices which incorporate wild type B and Z domains of SpA, where more than one site on the ligand is attached to a
chromatography matrix (i.e.. multipoint attachment); those described in U.S. Patent Publication No. 20100048876, which discusses chromatography ligands based on the wt C domain of SpA. which are capable of binding the Fab portions of some antibodies and are coupled to an insoluble carrier at a single site using a terminal coupling group; and those described in U.S. Patent No. 6,83 1 , 161 , which discusses SpA-based alkaline based chromatography ligands where one or more asparagine amino acid residues hav been modified.
[0043] As discussed above, while these ligands exhibit a reduced loss in binding capacity following exposure to alkaline conditions, some of these ligands show fragmentation during use in purification process, e.g.. the ligands described in U.S. Publication No. 20100221 844. which is highly undesirable. The ligands described herein, on the other hand, are far more attractive candidates for protein purification compared to the previously described ligands, in that they show reduced iragmentation following exposure to alkaline conditions during the regeneration and cleaning-in-place (CIP) protocols that are routinel used in protein purification processes.
[0044] In order that the present disclosure ma be more readily understood, certain terms are first defined. Additional definitions are set forth throughout the detailed description.
I. Definitions
[0045] As used herein, the term "SpA," "'Protein A" or "Staphylococcus aureus Protein A," refers to a 42Kda multf-domain protein isolated from the bacterium Staphylococcus aureus. SpA is bound to the bacterial cell wall via its carboxy-terminal cell wall binding region, referred to as the X domain. At the amifio- lerminal region, it includes five imnninoglobulin-binding domains, referred to as E, D, A, B, and C (Sjodhal. Eiir J Biochem. Sep 78(2):471-90 (1977); Uh!en e/ al., .7 Biol Cheni. Feb 259(3): 1695-702 (1 84). Each of these domains contains approximately 58 amino acid residues, and they share 65-90% amino acid sequence identity.
[0046] Each of the E, D, A, B and C domains of SpA possess distinct Ig- binding sites. One site is for Fey (the constant region of IgG class of Ig) and the other is for the Fab portion of certain Ig molecules (the portion of the Ig that is responsible for antigen recognition). It has been reported that each of the domains contains a Fab binding site. The non-lg binding portion of SpA is located at the C-terminus and is designated the X region or X-domain.
[0047] T he Z domain of SpA is an engineered analogue of the B domain of
SpA and includes a valine instead of an alanine at position 1 and an alanine instead of a.glycine residue, at position 29 (Nilsson. e «/., Protein engineering. Vol. 1. No. 2, 107-113, 1987.).
[0048] The cloning of the gene encoding SpA is described in U.S. Patent
No. 5, 1 51 ,350, the entire contents of which are incorporated by reference herein in their entirety.
[0049] The present invention provides affinity chromatography matrices which incorporate SpA-based ligands, where the ligands (both free as well as immobilized ligands) exhibit reduced fragmentation, as observed by SDS-PAGE and SEC, following regeneration and CIP protocols that are routinel used during protein purification process. (0050] In some aspects according to the present invention, an affinity ligand comprises one or more B domains or one or more Z domains or one or more C domains, or any combinations thereof where at least one B domain or at least one Z domain or at least one C domain comprises a deletion of 3 consecutive amino acids from the N-terminus, or 4 consecutive amino acids from the N-terminus or 5 consecutive amino acids from the N-terminus, startin at position 1 or at position 2.
[0051 J In some embodiments according to the present invention, more than one site of an affinity ligand is attached to a chromatography matrix (i.e., multipoint attachment). In a particular embodiment, the present invention provides an affinity chromatography matrix comprising one or more B domains of SpA attached to a chromatography matrix, where more than one site of the ligand is attached to the matrix and where at least one B domain has a deletion of 3. consecutive amino acids from the, N-terminus or 4 consecutive amino acids from the N-terminus. or 5 consecutive amino acids from the N-terminus, starting at position 1 or at position 2 of the wt B domain sequence.
[0052] In another embodiment, the present invention provides an affinity chromatography matrix comprising one or more Z domains of SpA attached, to a chromatography matrix, where more than one site of the ligand is attached to the matrix and where at least one Z domain has a deletion of 3 consecutive amino acids from the N-terminus or 4 consecutive amino acids from the N-terminus or 5 consecutive amino acids from the N-terminus. starting at position ,1 or position 2 of the wt Z domain sequence.
[0053] In yet another embodiment, the present invention provides an affinity chromatography matrix comprising one or more C domains of SpA, attached to a chromatography matrix, where more than one site of the ligand is attached to the matrix and where at least one C domain has a deletion of 3 consecutive amino acids from the N-lerminus or 4 consecutive amino acids from the N-terminus or 5 consecutive amino acids from the N-terminus, starting at position 1 or al position 2 of the wt C domain sequence.
[0054] In a particular embodiment, the present invention provides an alkaline stable affinity chromatography ligand which includes five C domains of SpA. with each domain including a G29 mutation as well as 4 amino acids deleted from the N-terminus, starting at position 1 , and the pentameric form including an extra alanine as the first amino acid to facilitate homogeneous post translational processing of the protein.
[0055] In some embodiments. SpA ligands described herein further include the glycine amino acid residue at position 29 replaced with a lysine amino acid residue (in case of B and C domains) or the alanine amino acid residue at position 29 replaced with a lysine amino acid residue (in case of Z domain).
|0056] The term "parental molecule" or "wild-type (wt) counterpart" or "wt protein" or "wt domain,"' as used herejii is intended to refer to a corresponding protei n (SpA) or a domain of a protein (e.g., B, Z or C domai ns of SpA) in its substantially native form., which is generally used as a control herein. A w counterpart control, as used herein, which corresponds to a SpA domain in its substantially native form may include one amino acid change from the corresponding SpA domain to alter Fab binding; however, is otherwise. identical in sequence to the corresponding wt domain. The ligands according to the present invention exhibit reduced fragmentation (in case of both free and immobilized forms) relative to their wt counterparts (i.e.. completely wt or including a mutation to alter Fab binding), as evidenced by the. experiments discussed in the Examples herein. In various embodiments, the wt counterpart of a B domain or C domain based ligand according to the present invention is the wt B domain of SpA or wt C domain of SpA, the amino acid sequences of which are set forth in SEQ ID NO:3 and SEQ JD Q:4.
respectively. In certain embodiments, a wt counterpart of a Z domain based ligand is the Z domain amino acid sequence set forth in SEQ ID NO:6. In certain
embodiments, a wt counterpart of a B, C or Z domai n, is substantially identical to the sequence of the B, C or Z domain mentioned above, but for a mutation at position 29 to alter the Fab-binding of the domain. Accordingly, in certain embodiments, a t counterpart of a B domain based ligand includes the amino acid sequence set forth in SEQ ID NO:45 (G29K), a wt counterpart of a C domain based ligand includes the amino acid sequence set forth in SEQ ID NO:46 (G29K) and the wt counterpart of a Z domain based ligand includes the amino acid sequence set forth in SEQ ID NO:48 (A29K). Further, in case a ligand according to the present invention includes more than one domain, the corresponding wt counterpart will include the same number of domains: however, may include a mutation to alter Fab binding. Accordingly, in certain embodiments, a wt counterpart of a pentameric C domain ligand according to the present invention includes the. amino acid sequence set forth in SEQ ID NO: 95 or in SEQ ID NO:96.
[0057] The term "sequence identity" means that two nucleotide or amino acid sequences, when optimally aligned, such as by the programs GAP or BESTFIT using default gap weights, share at least 70% sequence identity, or at least 80% sequence identity, or at least 85% sequence identity, or at least 90% sequence identity, or at least 95% sequence identity or more. For sequence comparison, typically one sequence acts as a reference sequence (e.g.. parent sequence), to which test sequences are compared. When using a sequence comparison algorithm, test and reference sequences are input into a computer, subsequence coordinates are designated, if necessary, and sequence algorithm program parameters are designated. The sequence comparison algorithm then calculates the percent sequence identity for the lest sequence(s) relative to the reference sequence, based on the designated program parameters.
[0058] Optimal alignment of sequences for comparison can be conducted, e.g., by the local homology algorithm of Smith & Waterman. Adv. Appl. Math. 2:482 ( 1981), by the homology alignment algorithm of Needleman & Wunsch, J. Mol. Biol. 48:443 (1970), by the search for similarity method of Pearson & Lipman, Pru . N i 'l. Acad. Sci. USA 85:2444 ( 1988), by computerized implementations of these algorithms (GAP, BESTFIT, FASTA, and TFASTA in the Wisconsin Genetics Software Package, Genetics Computer Group, 575 Science Dr., Madison, Wis.), or by visual inspection (see generally Ausubel et al.. Current Protocols in Molecular Biology). One example of algorithm that is suitable for determining percent sequence identity and sequence similarity is the BLAST algorithm, which is described in Altschul et al.. J. Mol. Biol. 215:403 (1990). Software for performing BLAST analyses is publicly available through the National Center for Biotechnology Information (publicly accessible through the National Institutes of Health NCBI internet server). Typically, default program parameters can be used to perform the sequence comparison, although customized parameters can also be used. For amino acid sequences, the BLASTP program uses as defaults a wordlengih (W) of 3, an expectation (E) of 10, and the BLOSUM62 scoring matrix (see Henikoff & Henikoff, Proc. Natl. Acad. Sci. USA 89: 1091 5 ( 1989)).
[0059] As used interchangeably herein, the terms 'Έ domain." "E domain of
SpA." and "E domain of Staphylococcus aureus Protein A," refer to the polypeptide whose amino acid sequence is set forth in SEQ ID NO: 1 or that encoded by, e.g.. the nucleotide sequence set forth in SEQ ID NO:7. The "E domain" is a 51 amino acid polypeptide that folds into a three-helix bundle structure. It is capable of binding Fc via residues on the surface of helices I and 2, or to Fab via residues on the surface of helices 2 and 3.
[0060] As used interchangeably herein, the terms "D domain," "D domain of SpA," and "D domain of Staphylococcus aureus Protein A." refer to the polypeptide whose amino acid sequence is set forth in SEQ I D NO:5 or that encoded by e.g.. the nucleotide sequence set forth in SEQ ID NO: l I . The "D domain" is a 61 amino acid polypeptide that folds into a three-helix bundle structure. It is capable of Fc binding via residues on the surface of helices 1 and 2. or to Fab via residues on the surface of helices 2 and 3.
[0061 1 As used interchangeably herein, the terms :'A domain," "A domain of SpA," and "A domain of Staphylococcus aureus Protein A," refer to the polypeptide whose amino acid sequence is set forth in SEQ ID NO:2 or that encoded by, e.g., the nucleotide sequence set forth in SEQ ID NO:8. The "A domain" is a 58 amino acid polypeptide that folds into a three-helix bundle structure. It is capable of Fc binding via residues on the surface of helices 1 and 2. or to Fab via residues on the surface of helices 2 and 3.
[0062] As used interchangeably herein, the terms "B domain." "B domainof SpA," and "B domain of Staphylococcus aureus Protein A," refer to the polypeptide whose amino acid sequence is set forth in SEQ ID NO:3 or that encoded by, e.g.. the nucleotide sequence set forth in SEQ I D NO:9. The "B domain" is a 58 amino acid polypeptide that folds into a three-helix bundle structure. It is capable of Fc binding via residues on the surface of helices 1 and 2, or to Fab via residues on the surface of helices 2 and 3.
[0063] In some embodiments, a B domain based ligand according to the present invention includes a deletion of three amino acids from the N-terminus. e.g., having the amino acid sequence set forth in SEQ ID NO: 13. In other embodiments, a B domain based ligand according to the present invention includes a deletion of four amino acids from the N-terminus. e.g.. having the amino acid sequence set forth in SEQ I D NO:28. In another embodiment, a B domain based ligand according to the present invention includes a deletion of five amino acids from the N-terminus (sequence not shown). [0064] As used interchangeably herein, the terms i-C domain.'* ;1C domain of
SpA." and :"C domain of Staphylococcus aureus Protein A." refer to the polypeptide whose amino acid sequence is set forth in SEQ I D NO:4 or that encoded by. e.g.. the nucleotide sequence set forth in SEQ ID NO: 10. The "C domain"* is a 58 amino acid polypeptide that folds into a three-helix bundle structure. It is capable of Fc binding via residues on the surface of helices I and 2. or to Fab via residues on the surface of helices 2 and 3.
[0065] In some embodiments, a C domain based ligand according to the present invention includes a deletion of three amino acids from the N-terminus.-e.^., having the amino acid sequence set forth in SEQ ID NO: 14. In other embodiments, a C domain based ligand according to the present invention includes a deletion of four amino acids from the N-terminus, e.g.. having the amino acid sequence set forth in SEQ ID NO:29. In another embodiment, a C domain based ligand according to the present invention includes a deletion of five amino acids from the N-terminus (sequence not shown).
[0066] As used interchangeably herein, the terms "Z domain.'" "Z domain of
SpA" and "Z domain of Protein A," refer to the three helix, 58 amino acid polypeptide that is a variant of the B domain of protein A. The amino acid sequence of the Z domain is set forth in SEQ ID NO:6 and the nucleic acid sequence is set forth in SEQ ID NO: 12. An exemplary Z domain is described in Nilsson el a!.. Protein Engr.f 1 .-107-1 13 ( 1 87), the entire contents of which are incorporated by reference herein.
[0067] In some embodiments, a Z domain based ligand according to the present invention includes a deletion of three amino acids from the N-terminus. e.g., having the amino acid sequenc set forth in SEQ ID NO: 1 5. In other embodiments, a Z domain based ligand according to the present invention includes a deletion of four amino acids from the N-terminus, e.g., having the amino acid sequence set forth in SEQ ID NO:30. In another embodiment, a Z domain based ligand according to the present invention includes a deletion of five amino acids from the N-terminus (sequence not shown).
[0068] In some embodiments, more than one site of the ligands described herein is attached to a solid support (i.e., multipoint attachment) and where the ligands show reduced fragmentation (in case of both free and attached ligands) during use in purification processes, as evidenced by SDS-PAGE or SEC. [0069] The term "reduced fragmentation." as used herein, refers to a decrease in the number and/or intensity of fragments of a ligand. as seen on an SDS- PAGE gel or by SEC. relative to a wt counterpart of the ligand, following exposure of the free ligand molecule or the ligand molecule immobilized onto a solid support, to alkaline conditions during the purification process. In some embodiments, the ligand is immobilized onto a solid support via multipoint attachment. Fragmentation is usually detected by the presence of lower molecular bands relative to the intact molecule on an SDS-PAGE gel or as distinct peaks having different retention times on an SEC chromatogram.
[0070] The SpA ligands according to the present invention exhibit reduced fragmentation, which can be detected as follows. For example, the free ligand can be exposed directly to 0.1 M NaOH, 0.3 NaOH or 0.5.M NaOH for 25 hrs, followed by a pH adjustment to 7.0 and can be subsequently analyzed by SDS-PAGE or SEC using standard protocols. Alternatively, a ligand immobilized onto a chromatography matrix can be exposed to 0.1 M NaOH, 0.3M NaOH or 0.5 NaOH for 25 hrs. The caustic supernatant is subsequently separated from the matrix (e.g.. a resin) and neutralized to pH 7. This supernatant can then be analyzed by SDS-PAGE or by SEC using standard protocols. In the case of SDS-PAGE. the relative optical intensity of the fragments can be observed visually and compared to a suitable control (e.g., a wt domain of SpA or an SpA domain containing a mutation at position 29, as described herein). In the case of SEC, the relative peak intensity can be observed and compared to a suitable control (e.g., a wt domain of SpA or an SpA domain containing a mutation at position 29, as described herein).
[0071 ] A typical purification process using an affinity chromatography matrix im olves regeneration of the matrix after each cycle of use employing an acidic or an alkaline solution, the latter being preferable. In addition, typical processes also involve CIP steps, which employ use of an acidic or alkaline solution to sanitize the matrix, alkaline solutions being preferable. Accordingly, an affinity chromatography matrix is expected to be exposed to several cycles of regeneration and CIP steps in its lifetime, thereby resulting in a significant loss in binding capacity for a target molecule over time.
[0072] The chromatography matrices incorporating the ligands according to the present invention are alkaline stable in addition to exhibiting reduced
fragmentation during use in puri fication processes, in that they show a reduced loss of binding capacity for a target molecule over time, following extended exposure to alkaline conditions during regeneration and CI P steps.
[0073] The term "alkaline-stable," "alkaline stabi lity," "caustic stable" or "caustic stability," as used herein, generally refers to the ability of an affinity ligand according to the present invention, either alone or when immobilized onto a chromatography matrix, to withstand repeated regeneration and CIP cycles using alkaline wash without losing its initial binding capacity. In general, it is assumed that a matrix by itself, onto which a ligand according to the invention is immobilized, contributes to less than a 5% change in stability after having been soaked in 0.5M NaOH for up to 30 hours. For example, in some embodiments, affinity ligands according to the invention are able to withstand conventional alkaline cleaning for a prolonged period of time, which renders the ligands attractive candidates, especial ly for cost-effective large-scale purification of immunoglobulins and Fc-containing proteins, many of which are therapeutic molecules.
1 07 1 In some embodiments, alkaline stabil ity refers to the ability of a ligand according to the present i nvention or a matrix incorporating. a ligand according to the present invention, to retain at least 65%, or at least 70%, or at least 75%, or at least 80%, or at least 85%, or at least 90%, or at least 95% of its initial binding capacity after 5 hours, or after 10 hours, or after 1 5 hours, or after 20 hours, or after 25 hours, or after 30 hours of incubation in 0.05 NaOH, O. lM NaOH, 0.3M NaOH or 0.5'M NaOH. In another embodiment, alkaline stability refers to a decrease in the initial binding capacity of the ligand by less than 70%, or less than 60%, or less than 50%, or less than 40%, or less than 30% even after treatment with 0.05M NaOH, 0. 1 M NaOH, 0.3 NaOH or 0.5M NaOH for 5 hours or 7.5 hours or 10 hours or 1 5 hours or 20 hours or 25 hours or 30 hours. In a particular embodiment, a chromatography matrix incorporating a ligand according to the present invention retains up to 95% of its initial binding capacity after exposure to 0.5N NaOH for 5 hours. In another embodiment, a chromatography matrix incorporating a ligand according to the present invention retains up to 95% of its initial binding capacity after exposure to 0. 1 M NaOH for 25 hours. In yet another embodiment, a chromatography matrix incorporating a ligand according to the present invention retains up to 85% of its initial binding capacity after exposure to 0.3 NaOH for 25 hours. In a further embodiment, a chromatography matrix incorporating a ligand according to the present invention retains up to 65% of its initial binding capacity after exposure to 0.5M NaOH for 25 hours. [0075] In some embodiments. SpA-based chromatography matrices according to the present invention exhibit an increased or improved alkaline stability as compared to matrices including wild type SpA domains. However, in other embodiments. SpA-based chromatography matrices according to the present invention are not more alkaline stable than the matrices including wild-type counterparts of the ligands. One such example is a ligand based on the pentameric C domain of SpA which is not more alkaline stable than its wi ld-type pentameric C domain counterpart. It is understood that in certain instances, both the wild-type and the variants of SpA domains may include a G29 mutation to reduce Fab binding; however, such mutation does not itself have an effect on alkaline stability (data not shown).
[0076] Alkaline stability can be readily measured by one of ordinary skill in the art using routine experimentation and/or as described herein.
[0077] The term "initial binding capacity." as used herein, refers to the amount of a target molecule (e.g., an immunoglobulin or an Fc-containing protein) that can be captured by a unit volume of an. affinity chromatography matrix (i.e., a matrix including an affinity ligand) prior to exposure of the matrix to alkaline conditions.
[0078] In some embodiments according to the present invention, affinity chromatography matrices including the ligands described herein (i.e., containing one or more SpA B, Z or C domains including N-terminal deletions described herein) exhibit less than 5%. or less than 6%, or less than 7%, or less than 8%, or less than 9%, or less than 10%. or less than 12%, or less than 1 5%, or less than 17%. or less than 20%, or less than 25%, or less than 30% loss in the initial binding capacity of a target molecule relative to an affinity chromatography matrix containing a corresponding wt SpA domain counterpart, as described herein, following extended exposure to caustic conditions. In some
embodiments, the affinity chromatography matrices according to the present invention retain at least 95%, or at least 90%, or at least 85%, or at least 80%, or at least 75%, or at least 70% of the initial binding capacity of a target molecule relative to an affinity chromatography matrix containing a corresponding wt SpA domain counterpart, followin extended exposure to caustic conditions. However, in some other embodiments, the chromatography matrices according to the present invention exhibit similar binding capacity to matrices containing wt counterpart of the ligand following extended exposure to caustic conditions. One such exemplary chromatography matrix includes a ligand that includes 5 or more C domains of SpA, where each domain includes 4 amino acids deleted from the -terminus where the ligand is not more alkaline stable than its wild-type C domain counterpart. Both the deletion form and the wild-type counterpart may contain a G29K mutation. Further, in various embodiments described herein, the SpA ligands may further include a single amino acid such as, an alanine, a valine or a glycine, at the N- terminus of only the first domain in a multimer, where the extra amino acid facilitates homogeneous post-translational processing.
[0079] The binding capacity of an affinity chromatography ligand for a target molecule can be readily measured using methods known in the art and those. described herein, e.g., as described in U.S. Patent Publication No. 20100221844. incorporated by reference herein in its entirety.
[0080] The term "chromatography," as used herein, refers to a dynamic separation technique which separates a target molecule of interest (e.g.. an
immunoglobulin or an Fc-containing'prptein) from other molecules in the mixture and allows it to be isolated. Typically, in. a chromatography method, a mobile phase (liquid or gas) transports a sample containing the target molecule of interest across or through a stationary phase (normally solid) medium. Differences in partition or affinity to the stationary phase separate the different molecules while mobile phase carries the different molecules out at different time.
[0081 1 The term "'affinity chromatography." as used herein, refers to a mode of chromatography where a target molecule to be separated is isolated by i ts
interaction with a molecule (e.g.. an alkaline, stable chromatography ligand) which specifically interacts with the target molecule. In one embodiment, affinity
chromatography involves the addition of a sample containing a target molecule (e.g.. an immunoglobulin or an Fc-containing protein) to a solid support which carries on it an SpA-based ligand, as described herein.
[0082] The term "Protein A affinity chromatography," as used herein, refers to the separation or isolation of substances using Protein A or SpA-based ligands.
such as those described herein, where the SpA or Protein A ligand is immobilized, e.g., on a solid support. Examples of Protein A affinity chromatography media/resin known in the art include those having the Protein A immobilized onto a controlled pore glass backbone, e.g., PROSEP A™ and PROSEP vA™ media/resin
(MILLI.PORE): those having Protein A immobilized onto a polystyrene solid phase, e.g., the POROS 50A™ and Poros MabCapture A™ media/resin (APPLIED
BIOSYSTEMS, INC.); and those having Protein A immobilized on an agarose solid support, e.g., rPROTEIN A SEPHAROSE FAST FLOW™ or MABSELECT™ media or resins (GE HEALTHCARE).
[0083] In addition to the aforementioned matrices, Protein A may also be immobi lized onto a hydrophilic crossl inked polymer. See, e.g.. U.S. Patent
Publication No. 20080210615, incorporated by reference herein in its entirety, which describes exemplary hydrophilic crosslinked polymers. Without wishing to be bound by theory, it is contemplated that the ligands encompassed by the present invention may be immobilized onto hydrophilic crosslinked polymers, such as those described in U.S. Patent Publication No. 2008021061 5.
[0084] The term "affinity matrix" or "affinity chromatography matrix," as used interchangeably herein, refers to a chromatographic support onto which an affinity chromatography ligand (e.g., SpA or a domain thereof) is attached. The ligand is capable of binding to a molecule of interest through affinity interaction (e.g., an immunoglobulin or an Fc-containing protein) which is to be puri fied or removed from a mixture. Exemplary Protein A based affinity chromatography matrices for use in Protein A based affinity chromatography which are known in the art include Protein A immobilized onto a control led pore glass backbone, e.g., the PROSEP A™ and PROSEP vA™ resins, High Capacity, Ultra and PROSEP U ltra Plus
(M1LLI PORE); Protein A immobilized on a polystyrene solid phase, e.g. the POROS 50A™ resin and POROS abCapture A™ (APPLIED BIOSYSTEMS); or Protein A immobil ized on an agarose solid phase, for instance the rPROTEIN A SEPHAROSE FAST FLOW™ or MABSELECT™ resin (G E HEALTHCARE).
[0085] The term "immunoglobulin." "Ig" or "antibody" (used
interchangeably herein) refers to a protein having a basic four-polypeptide chain structure consisting of two heavy and two light chains, said chains being stabilized, for example, by interchain disulfide bonds, which has the ability to speci ficall bind antigen. The term "single-chain immunoglobulin" or "single-chain antibody" (used interchangeably herein) refers to a protein having a t o-polypeptide chain structure consisting of a heavy and a light chain, said chains being stabilized, for example, by interchain peptide linkers, which has the ability to specifically bind antigen. The term "domain" refers to a globular region of a heavy or light chain polypeptide comprising peptide loops (e.g. , comprising 3 to 4 peptide loops) stabilized, for example, by β- pleated sheet and/or intrachain disul fide bond. Domains are further referred to herein as "constant" or "variable", based on the relative lack of sequence variation within the domains of various class members in the case of a "constant" domain, or the significant variation within the domains of various class members in the case of a ''variable" domain. Antibody or polypeptide "domains" are often referred to interchangeably in the art as antibody or polypeptide "regions". The "constant" domains of antibody l ight chains are referred to interchangeably as "light chain constant regions", "light chain constant domains'"". "CL" regions or "CL" domains. The "constant" domains of antibody heavy chains are referred to interchangeably as "heavy chain constant regions", ' heavy chain constant domains". "CH" regions or "CH domains. The "variable" domains of antibody l ight chains are referred to interchangeably as "light chain variable regions", "light chain variable domains". "VL" regions or " L" domains. The "variable" domains of antibody heavy chains are referred to interchangeably as "heavy chain variable regions", "heavy chain variable domains", "VH" regions or "VH" domains.
[0086] Immunoglobulins or antibodies may be monoclonal or polyclonal and may exist in mononieric or polymeric form, for example, IgM antibodies which exist in pentameric form and/or IgA antibodies which exist in mononieric. dimeric or multimeric form. The term "fragment" refers to a part or portion of an antibody or antibody chain comprising fewer amino acid residues than an intact or complete antibody or antibody chain. Fragments can be obtained via chemical or enzymatic treatment of an intact or complete antibody or antibody chain. Fragments can also be obtained by recombinant means. Exemplary fragments include Fab. Fab', F(ab')2, Fc and/or Fv fragments.
[0087] The term "antigen-binding fragment" refers to a polypeptide portion of an immunoglobulin or antibody that binds an antigen or competes with intact antibody {i. e. , with the intact antibody from which they were derived) for antigen binding (i.e.. speci fic binding). Binding fragments can be produced by recombinant DNA techniques, or by enzymatic or chemical cleavage of intact immunoglobulins. Binding fragments include Fab, Fab', F(ab')2, Fv, single chains, and single-chain antibodies.
[0088] Also encompassed are fusion proteins including an antibody or fragment thereof as a part of the fusion protein.
[ 0089] The terms "polynucleotide" and "nucleic acid molecule," used interchangeably herein, refer to polymeric forms of nucleotides of any length, either ribonucleotides or deoxyribonucleotides. These terms include a single-, double- or triple-stranded DNA. genomic DNA, cDNA, RNA, DNA-RNA hybrid, or a polymer comprising purine and pyrimidine bases, or other natural, chemically or biochemically modified, non-natural or derivatized nucleotide bases. The backbone of the polynucleotide can comprise sugars and phosphate groups (as may typically be found in RNA or DNA). or modi fied or substituted sugar or phosphate groups. I n addition, a double-stranded polynucleotide can be obtained from the single stranded polynucleotide product of chemical synthesis either by synthesizin the
complementary strand and annealing the strands under appropriate conditions, or by- synthesizing the complementary strand (k novo using a DNA polymerase with an appropriate primer. A nucleic acid molecule can take many different forms, e.g., a gene or gene fragment, one or more exons, one or more introns, m'RNA, cD'NA, recombinant polynucleotides, branched polynucleotides, plasmids, vectors, isolated DNA of any sequence, isolated RNA of any sequence, nucleic acid probes, and primers. A polynucleotide may comprise modified nucleotides, such as methylated nucleotides and nucleotide analogs, uracyl, other sugars and linking groups such as fluororibose and thioate, and nucleotide branches. As used herein, "'DNA" or "nucleotide sequence" includes not only bases A, T, C. and G. but also includes any of their analogs or modified forms of these bases, such as methylated nucleot ides, internucleotide modi fications such as uncharged linkages and thioatcs, use of sugar analogs, and modified and/or alternative backbone structures, such as polyamides. In a particular embodiment, a nucleic acid molecule comprises a nucleotide sequence encoding a variant of SpA, as described herein.
[0090] The term "Fc-binding," ''binds to an Fc portion" or "binding to an Fc portion" refers to the ability of an affinity ligand described herein, to bind to the constant part (Fc) of an antibody. In some embodiments, a ligand according to the present invention binds an Fc portion of an antibody (e.g.. human IgG l , IgG2 or lgG4) with an affinity of at least 10"7 M. or at least 10'8 M, or at least \ 0' M.
[0091 As used herein, the term "Fab binding" or "binding to a Fab portion" refers to the ability of an affinity ligand described herein, to bind to a Fab region of an antibody or an immunoglobulin molecule. The term "reduced binding to a Fab portion" refers to any decrease in binding to a Fab (or F(ab)2) portion of an immunoglobulin molecule by a SpA-based ligand according to the present invention relative to a control (e.g., a wt SpA domain), where the ligand further includes a mutation in one or more amino acids. In some embodiments, a ligand according to the present invention and its wt counterpart (used as a control) includes the glycine residue at position 29 replaced with an amino acid other than alanine or tryptophan. In a particular embodiment, a ligand according to the present invention includes a lysine residue at position 29. In a particular embodiment, binding to a Fab portion of an immunoglobulin molecule by a ligand described herein is undetectable using conventional techniques in the art and those described herein. Binding to an immunoglobulin molecule can be detected using well known techniques including those described herein and including but not limited to. for example, affinity chromatography and surface plasmon resonance analysis. In some embodiments, an immunoglobulin binding protein encompassed by the present invention binds an immunoglobulin molecule with an affinity of at least I 0"'° .
[0092] The term *'N-terminus," as used herein, refers to amino-terminus of the amino acid sequence of a SpA domain, starting at position 1 or at position 2 of the amino acid sequence of each of the domains, as depicted in Figure 1 . However, it is understood that the first amino acid in a sequence may be preceded by a methionine amino acid residue or another amino acid to facilitate homogenous post translational processing of the protein such as, for example, an alanine, a glycine or a valine. The SpA ligands described herein include a deletion of at least 3. or at least 4, or at least 5 consecutive amino acids from the N-terminus (starting at position 1 or at position 2 of B, C or Z domain amino acid sequences shown in Figure 1 ) of a SpA domain. In other words, such ligands include a deletion of consecutive amino acids 1 through 3, or consecutive amino acids 1 through 4, or consecutive amino acids 1 through 5 etc.. of SpA domains B, Z or,C or such ligands include a deletion of consecutive amino acids 2 through 4. or consecutive amino acids 2 through 5, or consecutive amino acids 2 through 6 etc.. of SpA domains B, Z or C (amino acid sequences of wt B, C and Z domains are depicted in Figure 1. which are modified to include deletions from the N- terminus). In a particular embodiment, a ligand according to the present invention includes 5 C domains, with each domain including a deletion of 4 consecutive amino acids from the N-terminus, starting at position 1.
[0093J The amino acid sequence of the B domain of SpA containing a deletion of 3 consecutive amino acids from the N-terminus is depicted in SEQ TD NO: 13. and that containing a deletion of 4 consecutive amino acids from the N- terminus is depicted in SEQ ID NO: 28. Additionally, the amino acid sequence of the C domain of SpA containing- deletion of 3 consecutive amino acids from the - terminus is depicted in SEQ ID NO: 14; and that containing a deletion of 4 consecutive amino acids from the N-terminus is depicted in SEQ ID NO: 29. Further the amino acid sequence of the Z domain containing a deletion of 3 consecutive amino acids from the N-terminus is depicted in SEQ ID NO: 15; and that containing a deletion of 4 consecutive amino acids from the N-terminus is depicted in SEQ I D NO: 30.
[0094] In general, in case of muitimeric forms of SpA-based ligands described herein, the amino acid sequences of the monomel ic forms of the ligands are simply repeated, as desirable. However, it is to be noted that, in case of some muitimeric forms of ligands according to the present invention, not all domains need to have a deletion from the N-terminus. For example, in some embodiments, ligands do not contain a deletion in the 'N-terminus of the first domain in the muitimeric form of ligand: however, subsequent domains in the ligand contain a delet ion of at least 3 consecutive amino acids from the N-terminus or at least 4 consecutive amino acids from the N-terminus or at least 5 consecutive amino acids from the N-terminus.
[0095] The SpA-based ligands according to the present invention harbor superior and unexpected properties, i.e., reduced fragmentation during use in purification processes, as evidenced by the Examples herein. Notably, the teachings in the prior art appear to teach away from the motivation to make and use such ligands. For example, U.S. Patent Publication No. 20100048876. discusses a ligand which includes a deletion in amino acid residues 3 through 6 of the C domain of SpA; however, based on the teachings of this publication (see. e.g.. Figure 2 of U.S. Patent Publication No. 20100048876), it appears that the deletion mutant described therein performs poorly with respect to retention of binding capacity relative to the wt C domain of SpA, over extended caustic exposure. Accordingly, based on the teachings of this reference, it would be less desirable to use a deletion mutant of a SpA C domain, when it loses more binding capacity over time, relative to its wild-type counterpart.
[0096] For the sake of convenience, the various sequences referenced through the application are summarized in Table I below. Tabic I
Brief Description of Sequence S'EQ I D
AA - Amino Acid: NA - Nucleic Acid; Δ -having a deletion NO:
E domain AA 1 A domain AA 2 β domain AA -> vvt C domain AA 4 wt D domain AA 5.
Z domain AA 6 wt E domain NA 7 wt A domain NA 8 wt 13 domain NA 9 wt C domain NA 10 wt D domain NA 1 1
Z domain NA 1 2
B domain Δ 3 AA monomer 13
C domain Δ 3 AA monomer 14
Z domain Δ 3 AA monomer 1 5
B domain Δ 3 AA dimer-both domains having deletion 1 6
C domain Δ 3 AA dimer-both domains having deletion 1 7
Z domain Δ 3..AA dimer-both domains having deletion 1 8
B domain Δ 3 AA dimer-only second domain has deletion 19
C domain Δ 3 AA dimer-only second domain has deletion 20
Z domain Δ 3 A A dimer-only second domain has deletion 21
B domain Δ 3 AA pentamer-all domains have deletion 22
C domain Δ 3 AA pentamer-all domains have deletion 23
Z domain Δ 3 AA pentamer-all domains have deletion 24
B domain Δ 3 AA penlamcr-first domain does not have deletion 25
C domain Δ 3 AA pentamer-first domain does not have deletion 26
Z domain Δ 3 AA pentamer-first domain does not have deletion 27
B domain Δ 4 A A monomer 28
C domain Δ 4 AA monomer 29
Z domain Δ 4 A A monomer 30
B domain Δ 4 AA dimer-both domains having deletion 3 1
C domain Δ 4 AA dimer-both domains having deletion 32
Z domain Δ 4 AA dimer-both domains having deletion
B domain Δ 4 AA dimer-only second domain has deletion 34
C domain Δ 4 AA dimer-only second domain has deletion 35
Z domain Δ 4 AA dimer-only second domain has deletion 36
B domain Δ 4 AA pentamer-al l domains have deletion 37
C domain Δ 4 AA pentamer-all domains have deletion 38
Z domain Δ 4 AA pentamer-all domains have deletion 39
B domain Δ 4 AA pentamer-first domain does not have deletion 40
C domain Δ 4 AA pentamer-first domain does not have deletion 41
Z domain Δ 4 AA pentamer-first domain does not have deletion 42 wt E domain AA non-Fab (G29K) 43 wi A domain AA non-Fab (G29 ) 44 wt B domain AA non-Fab (G29K) 45 wt C domain AA non-Fab (G29 ) 46 wt D domain A A non-Fab (G29K) 47
Z domain AA non-Fab (A29K) 48 wt E domain NA non-Fab (G29K) 49 wt A domain NA non-Fab (G29K) 50 wt B domain NA non-Fab (G29 ) 51 wt C domain NA non-Fab (G29lv) 52 wt D domain NA non-Fab (G29K) 53
Z domain NA non-Fab (A29K) 54
B domain Δ 3 AA monomer non-Fab (G29 ) 55
C domain Δ 3 AA monomer non-Fab (G29 ) 56
Z domain Δ 3 AA monomer non-Fab (A29K.) 57
B domain Δ 3 AA dimer-both domains having deletion non-Fab 58 (G29 )
C domain Δ 3 AA dimer-both domains having deletion non-Fab 59 (G29 )
Z domain Δ 3 AA dimer-both domains having deletion non-Fab 60 (A29K)
B domain Δ 3 AA dimer-only second domain has deletion non-Fab 61 (G29K)
C domain Δ 3 AA dimer-only second domain has deletion non-Fab 62 (G29 )
Z domain Δ 3 AA dimer-only second domain has deletion non-Fab 63 (A29K)
B domain Δ 3 AA pentamer-all domains have deletion non-Fab (G29K) 64
C domain Δ 3 AA pentamer-all domains have deletion non-Fab (G29 ) 65
Z domain Δ 3 AA pentamer-all domains have deletion non-Fab (A29K) 66
B domain Δ 3 AA pentamer-first domain does not have deletion non- 67 Fab (G29 )
C domain Δ 3 AA pentamer-first domain does not have deletion non- 68 Fab (G29 )
Z domain Δ 3 AA pentamer-first domain does not have deletion non- 69 Fab (A29 )
B domain Δ 4 AA monomer non-Fab (G29 ) 70
C domain Δ 4 A A monomer non-Fab (G29 ) 71
Z domain Δ 4 AA monomer non-Fab (A29 ) 72
B domain Δ 4 AA dimer-both domains having deletion non-Fab 73 (G29K)
C domain Δ 4 AA dimer-both domains having deletion non-Fab 74 (G29K)
Z domain Δ 4 AA dimer-both domains having deletion non-Fab 75 (A29 )
B domain Δ 4 AA dimer-only second domain has deletion non-Fab 76 (G29 )
C domain Δ 4 AA dimer-only second domain has deletion non-Fab 77 (G29 )
Z domain Δ 4 AA dimer-only second domain has deletion non-Fab 78 (A29K)
B domain Δ 4 A A pentamer-all domains have deletion non-Fab (G29K) 79
C domain Δ 4 A A pentamer-all domains have deletion non-Fab (G29K.) 80
Z domain Δ 4 AA pentamer-all domains have deletion non-Fab (A29 ) 81 B domain Δ 4 AA pentamer- first domain does not have deletion non- 82
Fab (G29. )
C domain Δ 4 AA pentamer-first domain does not have deletion non- 83
Fab (G29 )
Z domain Δ 4 AA pentamer-first domain does not have deletion non- 84
Fab (A29 )
Z domain dimer non-Fab (A29K) 85
I I is tag A 86
Z Domain Δ 1 AA dimer-first domain does not have deletion non-Fab 87
(A29K)
Z Domain Δ 2 AA dimer-first domain does not have deletion non-Fab 88
(A29 )
A Domain Δ 4 AA dimer-first domain has a N-terminal deletion 89
D Domain Δ 4 AA dimer-first domain has a N-terminal deletion 90
Z domain pentamer non-Fab (A29K) 91
C domain dimer AA 92
C domain Δ 4 AA pentamer with the first domain having N-terminus alanine non-Fab
(G29K) 93
C domain Δ 4 AA pentamer with the first domain with N-terminus alanine 94
C domain pentamer non-Fab (G29K) AA 95
C domain pentamer wild type A A 96
11. Generation of SpA-based Molecules for Use as Chromatography
Ligands
[0097] The SpA-based affinity chromatography ligands encompassed by the present invention can be made using any suitable methods known in the art.
[0098] For example, as an initial step, standard genetic engineering techniques, e.g., those described in the laboratory manual entitled Molecular Cloning by Sambrook, Fritsch and Maniatis, may be used for the generation of nucleic acids which express the SpA ligancl molecules described herein.
[0099] In some embodiments, a nucleic acid molecule encoding one or more domains of SpA having an N-terminus deletion can be cloned into a suitable vector for expression in an appropriate host cell. Suitable expression vectors are well-known in the art and typically include the necessary elements for the transcription and translation of the variant SpA coding sec|uence.
[00100] SpA molecules described herein may also be synthesized chemically from amino acid precursors for fragments using methods well known in the art. including solid phase peptide synthetic methods such as the Boc'(tert- butyloxycarbonyl) or Fmoc (9-fluorenylmethyloxy carbonyl) approaches (see, e.g., U.S. Pat. Nos. 6,060.596; 4,879,378: 5.198.531 ; 5.240.680). [00101] Expression of SpA molecules described herein can be accomplished in a variety of cells types such as, e.g., eiikaryolic host cells such as yeast cells, insect cells and mammalian cells and prokaryotie host cells, e.g.. bacteria such as E. coli.
[00102] In some embodiments, SpA molecules may be expressed on the surface of a bacteriophage such that each phage contains a ON A sequence that codes for an individual SpA molecule displayed on the phage surface. The affinity of the SpA molecule for an immunoglobulin can be readily assayed for using standard techniques in the art and those described herein, e.g.. EIJSA and Biacore™ 2000 standard set up (BIACORE AB, Uppsala Sweden). It is desirable that the binding affinity of a SpA molecule of the present invention to an immunoglobulin is at least comparable with that of the parent molecule, where the molecule exhibits reduced fragmentation during use. as described herein.
III. Supports Used for the Preparation of Chromatography Matrices
[00103] In some embodiments, SpA ligands encompassed by the present invention are immobilized onto a support, e.g., a solid support or a soluble support, to generate an affinity chromatography matrix suitable for the separation o
biomolecules such as, e.g.. immunoglobulins and Fc-containing proteins.
[00104] In some embodiments, a ligand according, to the present invention is immobilized onto a solid support. Without wishing to be bound by theory, it is contemplated that any suitable solid support may be used for the attachment of a ligand according to the invention. For example, solid support matrices include, but are not limited to, controlled pore glass, silica, zirconium oxide, titanium oxide, agarose,, polymethacrylate, polyacrylate, poiyacrylamide. polyvinylelher, polyvinyl alcohol and polystyrene and derivatives thereof (e.g., alloys thereof). A solid support may be a porous material or a non-porous material.
[00105 ] In some embodiments, a solid support is a porous material. A porous material used as a solid support may be comprised of a hydrophilic compound, a hydrophobic compound, an oleophobic compound, an oleophilic compound or any combination thereof The porous material may be comprised of a polymer or a copolymer. Examples of suitable porous materials, include, but are not limited to polyether sulfone, polyamide, e.g.. nylon, polysaccharides such as, for example, agarose and cellulose, polyacrylate, polymethacrylate, poiyacrylamide.
poiymelhacrylamide. polytetrafluoroeihylene, polysulfone. polyester, polyvinylidene fluoride, polypropylene, polyethylene, polyvinyl alcohol, polyvinylether, polycarbonate, polymer of a fluorocarbon, e.g. poly (tetrafiuoroelhylene-co- perfluoro(alkyl vinyl ether)), glass, silica, zirconia, titania, ceramic, metal and alloys thereof.
100106 j The porous material may be comprised of an organic or inorganic molecule or a combination of organic and inorganic molecules and may be comprised of one or more functional groups, e.g.. a hydroxy! group, an epoxy group, a thiol group, an amino group, a carbonyl group, or a carboxylic acid group, suitable for reacting, e.g.. forming covalent bonds for further chemical modification, in order to covalently bind to a protein. In another embodiment, the porous material may not possess a functional group but can be coated with a layer of material that bears functional groups such as, a hydroxyl group, a thiol group, an amino acid group, a carbonyl group, or a carboxylic acid group.
[001 07] In some embodiments, a conventional affinity separation matrix is used, e.g.. of organic nature and based on polymers that expose, a hydrophi lic surface to the aqueous media used, i.e. expose hydroxy (--Oi l),, carboxy (— COOH), carbonyl (-CI IO. or RCO-R/), carboxamido (-CO Hi, possibly in N-substituted forms), amino (- l h, possibly in substituted form), oligo- or polyethylenoxy groups on their external and, i f present, also on internal surfaces. In one embodiment, the polymers may. for instance, be based on polysaccharides, such as dextran, starch, cellulose, pul lulan, agarose elc, which advantageously have been cross-linked, for instance with biscpoxides, epihalohydrins, al lyl bromide, allyglycidyl ether. 1 ,2.3-trihalo substituted lower hydrocarbons, to provide a suitable porosity and rigidity. In another embodiment, the solid support comprises porous agarose beads. The various supports used in the present invention can be readily prepared according to standard methods known in the art, such as, for example, inverse suspension gelation described, e.g., in Hjerten. Biochim Biophys Acta 79(2), 393-398 ( 1 964). Alternatively, the base matrices can be commercially available products, such as Sepharose™ I'astFlow (GE H EALTHCARE. Uppsala. Sweden ). In some embodiments, especially advantageous for large-scale separations, the support is adapted to increase its rigidity, and hence renders the matrix more suitable for high flow rates.
[00108] Alternatively, the sol id support can be based on synthetic polymers, such as polyvinyl alcohol, polyvinylether, polyhydroxyalkyl acrylates,
polyhydroxyalkyl methacrylates. polyacrylamides, polymethacrylamides etc: I n case of hydrophobic polymers, such as matrices based on divinyl and monovinyl- substituted benzenes, the surface of the matrix is often hydrophilized to expose hydrophilic groups as defined above to a surrounding aqueous liquid. Such polymers can be easily produced according to standard methods, see e.g., Aishady, C/iiniica e L'Industria 70(9), 70-75 ( 1988). Alternatively, a commercially available product, such as Source™ (GE HEALTHCARE, Uppsala, Sweden) and Poros (APPLIED BIOSYSTEMS. Foster City. CA) may be used.
10010 1 In yet other embodiments, the solid support comprises a support of inorganic nature. eg..silica, zirconium oxide, titanium oxide and alloys thereof. The surface of inorganic matrices is often modified to include suitable reactive groups for further reaction to SpA and its variants. Examples include CM Zirconia (Ciphergen- BioSepra (CERG YPO TOISE, France) and CPG® (MILLIPORE).
[001 10] In some embodiments, the solid support may, for instance, be based on zirconia, titania or silica in the form of controlled pore glass, which may be modified to either contain reactive groups and/or sustain caustic soaking, to be coupled to ligands.
[001 1 1 ] Exemplary solid support formats include, but are not limited to, a bead (spherical or irregular), a hollow fiber, a solid liber, a pad, a gel, a membrane, a cassette, a column, a chip, a slide, a plate or a monolith.
( 001 12] With respect to the format of a matrix, in one embodiment, it is in the form of a porous monolith, which may be made using an inorganic material such as, e.g.. silica, or an organic material such as, e.g. polymethacrylale. polyacrylate, polyacrylamide, polymethacrylamidc, polytetrafluoroethylene, polysulfone, polyester, polyvinylidene fluoride, polypropylene, polyethylene, polyvinyl alcohol,
polyvinylether and polycarbonate. In case of a monolith, it may be formed via polymerization or by coaling a substrate.
[001 13] In an alternative embodiment, the matrix is in beaded or particle form that can be porous or non-porous. Particles may be spherical or non-spherical as well as magnetic or non-magnetic. 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. Also, solid support in forms such as a surface, a chip, a capillar)', or a filter may be used.
[001 14] The matrix could also be in the form of membrane in a cartridge. The membrane could be in flat sheet, spiral, or hollow fiber format.
[001 15] In another embodiment, a ligand according to the present invention is attached to a soluble support, e.g., a soluble polymer or a water soluble polymer. Exemplary soluble supports include, but are not limited to, a bio-polymer such as. e.g.. a protein or a nucleic acid. In some embodiments, bioiin maybe used as a soluble polymer, e.g., as described in US Patent Publication No. 20080108053. For example, biotin may be bound to a ligand, e.g.. a SpA-based ligand according to the present invention, which subsequent to being bound to the ligand. can be used for isolating a protein of interest, e.g., an antibody or fragment thereof, e.g.. present in a crude mixture and the protein of interest can be isolated or separated via precipitation of the biotin-ligand-protein polymer complex in either a reversible or irreversible fashion. The polymer may also be a synthetic soluble polymer, such as, for example, including but not limited, to a polymer containing negatively charged groups
(carboxylic or sulfonic), positively charged groups (quartemary amine, tertiary amine, secondary or primary groups), hydrophobic groups (phenyl or butyl groups), hydrophi!ic groups (hydroxy!, or amino groups) or a combination of the above.
Exemplary synthetic soluble polymers can be found i International PCI Publication No. WO2008091740 and U.S. Publication No. US20080255027, the entire teachings of each of which are incorporated by reference herein. These polymers, upon specific physical changes in one or more conditions such as pH, conductivity or temperature, can be used to purify the protein of interest via precipitation in either a reversible or an irreversible fashion. Synthetic soluble polymers may be used alone or may be coupled with a ligand according to the present invention and used for
capture/puri fication of a protein of interest such as, e.g., an antibody or a fragment thereof, via precipitation in either a reversible or an irreversible fashion.
[001 16] In some embodiments, ligands are attached to a membrane in a multi-well plate format. In yet other embodiments, the ligands are incorporated into a capillary or a microfluidics device. I V. Methods for Attaching a Ligand to a Support
[001 17] Any suitable technique may be used for attaching a ligand described herein to a support, e.g.. a solid support including those well-known in the art and described herein. For example, in some embodiments, the ligand may be attached to a support via conventional coupling techniques utilizing, e.g. amino and/or carboxy groups present in the ligand. For example, bisepoxides, epichlorohydrin. CNBr, N- hydroxysiiccinimide (NHS) etc.. are well-known coupling reagents. In some embodiments, a spacer is introduced between the support and the ligand, which improves the availability of the ligand and facilitates the chemical coupling of the ligand to the support.
[001 18] In various embodiments encompassed by the present invention, more than one site on a ligand is attached to a solid support such (i.e., via multipoint attachment), thereby resulting in an affinity chromatography matrix which shows reduced fragmentation of the ligand upon extended caustic exposure (both in case of the free ligand as well as the attached ligand).
[001 19] Attachment of a SpA-based chromatography ligand to a solid support can be achieved via many different ways known, most of which are vvell known in the art, as well as those described herein. See, e.g., Hermanson el al., Immobilized Affinity Ligand Techniques, Academic Press, pp. 51 - 136 ( 1992).
[00120] For example, protein ligands can be coupled to a solid support via active groups on cither the surface of the solid support or the protein ligand, such as. for example, hydrolxyl, thiol, epoxide, amino, carboiiyl. epoxide, or carboxylic acid group. Attachment can be achieved using known chemistries including, but not limited to. use of cyanogen bromide (CNBr). N-hydroxyl succinimide ester, epoxy (bisoxirane) activation, and reductive animation.
[00121 For example, thiol-directed protein coupling has been described in the literature. See. e.g.. Ljungquist, et al. Eur. J. Biochem. Vol 186, pp. 558-561 (1 89). This technique has been previously applied for coupling SpA to a solid support. Since wild type SpA does not contain thiol groups, the attachment is achieved by reconibinantly inserting a thiol containing cysteine at the C-terminus of SpA. See, e.g.. U.S. Patent No. 6,399.750. Several commercial products such as MabSelect™, MabSelect™ Xtra and MabSelect™ SuRe, MabSelect™ SuRe LX are produced via this mechanism. It has been reported that this terminal cysteine only reacts with the epoxide group on the solid surface, thereby resulting in single point attachment of the SpA to the solid support. See. e.g.. Process Scale Biosepurat ions for the Biopliarmaceiilical Industry, CRC Press. 2006. page 473.
1001 22] In some embodiments according to the present invention, more than one site on the SpA-based chromatography ligands is attached to a sol id support via non-discriminate, multipoint attachment. In general. SpA contains abundant free amino groups from numerous lysines in each domain. The attachment of a SpA domain to a solid support via multipoint attachment, e.g.. a chromatography resin with epoxide or aldehyde group, can be achieved by reacting the amino group of lysine on SpA, via epoxide ring-opening or reductive animation, respectively. In certain embodi ments, multipoint attachment can be achieved by the reaction of one or more natural ly occurring amino acids on SpA having free hydroxy! groups, such as. for example, serine and tyrosine, with a support containing an epoxide group via a ring- opening reaction. Alternatively, multipoint attachment can be achieved, for example, by the reaction of naturally occurring amino acids on SpA having free carboxylic acid groups, such as, for example, aspartic acid and glutamic acid, with a support containing amino groups via. for example, Λ'.Λ' '-carbonyIdiimidazole. Multipoint attachment of the ligand to support can also be achieved by a combination of all the above mechanisms.
[001 23] SpA-based chromatography l igands may also be attached to a solid support via an associative mechanism. For example, an associative group may interact with a ligand of interest non-covalently via ionic, hydrophobic or a combination of interactions, thereby to attach ligand of interest onto the solid surface. This faci litates the high efficiency coupling of ligand to the solid matrix, for example, as described in U.S Patent Nos. 7,833,723 and 7.846,682, incorporated by reference . herein, thereby resulting in ligand density higher than that without the associative groups. Associative groups suitable for use in the invention include charged species such as ionic species, and uncharged species such as hydrophobic species. The associative group may modi fy the solid support, e.g. by covalently binding directly with the solid support. Suitable examples of ionic species may include quaternary amines, tertiary amines, secondary amines, primary amines, a sulfonic group, carboxylic acid, or any combination thereof. Suitable examples of hydrophobic species may include a phenyl group, a butyl group, a propyl group, or any combination thereof. It is also contemplated that mixed mode species may be used. The associative group may also interact with the protein ligand. Thus the interaction between the associative group and the protein ligand may be comprised of a mixture of interactions, e.g. ionic and hydrophobic species.
1001241 The associative group may be covalently coupled to the solid support by reacting a functional group' on the solid support with a functional group on the associative group. Suitable functional groups include, but are not limited to amines, hydroxyl, sulfhydryl, cafboxyl, imine, aldehyde, ketone., alkene, alkyne, azo, nitrile, epoxide, cyanogens and activated carboxylic acid groups. As an example, agarose beads contain hydroxyl groups which may be reacted with the epoxide functionality of a positively charged associative group, such as glycidyl trimethylammonium chloride. A skilled artisan will appreciate that a plurality of associative groups may be coupled to the solid support provided that at least one Afunctional associative group is used. Thus associative groups may be coupled in tandem to the solid support or they may be individually coupled directly to th¾ solid support.
1001251 In some embodiments, the present invention provides; associative groups and/ or protein ligands which may be coupled to a solid support wV/-an intervening linker. The linker may comprise at least one functional group coupled to a linkin moiety. The linking moiety may comprise any molecule capable of being coupled to a functional group. For example, the linking moiety may include any of an alkyl, an alkenyl, or an alkynyl group. The linking moiety may comprise a carbon chain ranging from 1 to 30 carbon atoms. In some embodiments the linker may be comprised of more than 30 carbon atoms. The linking moiety may comprise at least one hetero-atom such as nitrogen, oxygen and sulfur. The linking moiety may be comprised of a branched chain, an unbranched chain or a cyclic chain. The linking moiety may be substituted with two or more functional groups.
(00126] Choosing the appropriate buffer conditions for coupling a protein ligand to a solid support is well within the capability of the skilled artisan. Suitable buffers include, e.g., sodium acetate, sodium phosphate, potassium phosphate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium chloride, potassium chloride, sodium sulphate, etc. or any combination of the above, with the concentration ranging from l Om to 5M. In some embodiments, the concentration of salt ranges from 0.1 to 1 .5. .
[00127] Additional suitable buffers include any non-amine containing buffer such as carbonate, bicarbonate, sulfate, phosphate and acetate buffers, or a combination of the above. When associative chemistry is used, salt concentration of the buffer wil l depend on the associative group used. Tor example, the sail concentration may be in the range of 5nM-l 00m . Where a charged species is used, the salt concentration may be at least 5nM but less than 0. 1 M, at least 5nM but less than 0.01 i , at least 5n but less than 0.001 M. In certain embodiments, the salt concentration may be 0.01 M. Where a hydrophobic species is used a high salt concentration is usually desirable. Thus the salt concentration may be greater than 0.001 M. greater than 0.01 , or greater than 0.1 .
[ 00128] In some embodiments, when associative chemistry is used, the reaction is performed at a temperature ranging from 0°C to 99°C. In certain embodiments the reaction method is practiced at a temperature less than 60°C, less than 40°C, less than 20°C, or less than 1 °C. In some embodiments the method of the invention is practiced at a temperature of about 4°C. In other embodiments the method of the invention is practiced at a temperature of 20°C.
V. Assaying for Reduced Fragmentation of the Ligands
[ 00129] The present invention provides affinity chromatography matrices which incorporate SpA l igands based on one or more B, Z or C domains, where one or more domains include a deletion of 3 or 4 or 5 consecutive amino acids from the N-terminus, starting at position 1 or at position 2. In some embodi ments, more than one site on an SpA-based ligand is attached to a chromatography matrix.
[001 30] The present invention is based on an unexpected and surprising discovery that the ligands described herein, both in free form as well as when immobilized onto a solid support (e.g., a chromatography matrix ), exhibit reduced fragmentation following exposure to extended caustic conditions during use in purification processes. As discussed above, such fragmentation is undesirable as it leads to potentially immunogenic fragments of SpA domains ending up with the potentially therapeutic targe protein. Further the fragmentation makes the purification process more costly due to the need to use more ligand during the process.
[0013 1 ] Fragmentation of affinity ligands can be readily detected using methods known in the art and those described herein. Such methods include, but arc not limited to, SDS-PAG E and SEC. [00132] Sodium dodecyl sul fate (SDS)- polyacrylamide gel electrophoresis
(PAG E) is commonly used for molecular weight analysis of proteins. SDS is a detergent thai dissociates and unfolds proteins. The SDS binds to the polypeptides lo form complexes with fairly constant charge to mass ratios. The electi pphoretic migration rale throug a gel is therefore determined only by the size of the complexes. Molecular weights are determined by simultaneously running marker proteins of known molecular weight. The gel is typical ly stained and the presence of
biomolecules of different molecular weights caii be visualized.
[001 331 Size-exclusion chromatograph (SEC) is. a method in which molecules in solution are separated by their size. It is usually applied to large or macromolecular complexes such as proteins and industrial polymers. Detection of di fferent molecular species is typically performed by UV-Vis or by light scattering. In the case of UV-Vis, a wavelength speci fic lor detection of certain species is chosen. The orders in which certain molecular species elute, as observed on the chromatogram, as well as the intensity of corresponding peaks, provides information, on the species type as we'll as relative quantity.
[001 34] As demonstrated by the examples included herein, the SpA ligands according to the present invention exhibit reduced fragmentation relative to their vvt counterparts, following exposure to caustic conditions. In an exemplary experiment to show reduced fragmentation, a SpA ligand having an N-terminus deletion, as described herein, and its vvt counterpart, are both exposed to 0.5M NaOH for 25 hrs. The solution is then neutralized with an acid to pH 7. The neutralized solutions are injected into S C or loaded on to an SDS-PAG E gel for analysis and comparison.
[001 35] In another exemplary experiment to show reduced fragmentation, an affinity chromatography matrix including a ligand having an N-terminus deletion attached to a solid support (immobilized via multipoint attachment), as described herein, as well as an affinity chromatography matrix including its vvt counterpart attached to a solid support (immobilized via multipoint attachment), are both exposed to 0.5M NaOH for 25 hrs. The caustic solution and the matrix (e.g.. in the form of a resin ) are separated and immediately neutralized with an acid to pH 7. The neutralized solutions are injected into SEC or loaded on to an SDS-PAGE gel for analysis and comparison. VI. Assaying for Alkaline Stability of the Lteanrts
[00136] In addition to exhibiting reduced fragmentation during use in puri fication processes, the l igands described herein are also alkaline stable.
Subsequent to the generation of the chromatography matrices incorporating the SpA- based ligands described herein, the alkal ine stability of the matrices containing the ligands can be assayed using standard techniques in the art and those described herein.
[001 37] For example, the alkaline stability of a ligand immobilized onto a matrix can be assayed using routine treatment with NaOH at a concentration of about 0.5 , e.g., as described herein as well as in U.S. Patent Publication No.
20100221844. the entire content of which is incorporated by reference herein in its entirety.
[001 38] In some embodiments, alkal ine stable SpA molecules as .well as matrices incorporating the same exhibit an "increased" or "'improved" alkaline stability, meaning that the molecules and matrices incorporating the same are stabl under alkaline conditions for an extended period of t ime relative to their wt counterparts. Previously, it has been reported that chromatography matrices incorporating SpA ligands based on the wt B, C or Z domain of SpA or having a mutation of one or more asparagine residues provides an improved alkaline stabi lity under conditions where the pH is above about 10, such as up to about 1 3 or 14.
However, some of these l igands appear to show fragmentation during use. especially following repeated cycles of C1 P, as observed by the presence of fragments on an SDS-PAGE gel or by SEC.
[00 1 39] In some embodiments, ligands according to the present invention as well as matrices incorporating the same are no more al kal ine stable than their wt counterparts; nonetheless, they exhibit reduced fragmentation. One such ligand described herein is a penlameric form of the C domain ligand including an N-terniinus deletion in each of the domains and including a G29 mutation in each of the domains. Such a ligand may further include an alanine as the very first amino acid in the pentamer to facilitate homogenous post-translational processing.
[00140] The present invention is based on the surprising and unexpected discovery of novel SpA ligands (in both free form as well as well when immobilized into a chromatography matrix) which exhibit reduced fragmentation during use in purificalion processes relalive to some of the previously described ligands, in addition to retaining at least 95% of the initial binding capacity following extended exposure to caustic conditions (e.g., 0. 1 M NaOH for 25 hours or more). In some embodiments, more than one site on the ligands is attached onto a solid support and these ligands are based on B. C. or Z domains of SpA. where the ligands have a deletion of 3, 4 or 5 consecutive amino acids from the -terminus, starting at position I or at position 2.
[00141 ] In some embodiments, after 100 cycles, each cycle including a 15 min treatment with 0.5 NaOH, the percentage of retained binding capacity of the SpA ligands described herein (e.g.. those comprising one or more B, C or Z domains, and any combinations thereof, where at least one of B, C or Z domain includes a deletion of at least 3 consecutive amino acids from the N-terminus). is at least 1 .25 times more, 1 .5 times more. 2.0 times more, 2.5 times more, or 3 times more than that of the wt counterpart.
[001421 In one embodiment, the alkaline stability of the immobilized ligand, as assayed by the retention of IgG binding capacity over time, is measured as follows. The binding capacity, referred to as Qd 50%, is measured by obtaining the volume of IgG loaded to a concentration based on absorbance at UVseomn of 50% of the initial IgG concentration. The initial Qd 50% of the chromatography matrix (e.g., resin packed in a column) is measured first. The chromatography matrix (e.g.. resin as described above) is then exposed to about 10 cycles of 15 min exposure of 0.5M NaOH at 0.8 mL/min. Qd 50% is measured again. This process is repeated until the chromatography matrix is exposed to a total of about 100 cycles of 0.5M NaOH. Qd 50% is measured one last lime and the results from the affinity chromatography matrix including ligands (e.g.. chromatography resin immobilized with ligands) as described herein are compared with the respective type wt domains of SpA.
[00143] In another assay, caustic or alkaline stability of the matrix is measured by static soaking of the matrix. By soaking a measured amount of an affinity chromatography matrix (e.g.. in resin format) in 0.1 M NaOH, 0.3N NaOH or 0.5M NaOH for 25 his with gentle rotation and measuring IgG binding capacity before and after the NaOH soaking, the alkaline stability by way of retention of binding capacity of the matrix for IgG. can be determined. VI I. Methods of Purifying a Target Molecule Using a Chromatography Matrix of the I nvention
[ 00144 j I n some embodiments, the present invention provides a method of puri fying a target molecule from a mixture using the affinity chromatography matrices described herein. The target molecule may be any molecule which is recognized by an affinity ligand provided herein, where the ligand is coupled to a sol id support {i.e., a chromatography matrix). Examples of target molecules include immunoglobulins and Fc-containing proteins. The immunoglobul ins may be polyclonal antibodies or a monoclonal antibody or a functional fragment thereof. Functional fragments include any fragment of an immunoglobulin comprising a variable region that still binds speci fical ly to its antigen while at the same time retaining its abil ity to speci fically bind to a protein ligand coupled to a sol id support.
[00145] In some embodiments, a method of isolating a target molecule of interest using an affinity chromatography matrix described herein includes the steps of: (a) contacting a solid support including an immobilized SpA-based
chromatography ligand having an amino acid sequence selected from the group consisting of SEQ I D NOs: 13-42, SEQ ID NOs: 55-84 and SEQ ID NOs: 93-95, with a mixture comprising a target molecule under conditions such that the target molecule speci fically binds to the ligand; and (b) altering the conditions such that the target molecule is no longer bound to the ligand. thereby isolating the target molecule.
[00146] In some embodiments, the altering step includes altering the pH, such the target molecule is no longer bound to the l igand. In a particular embodiment, the pi t is altered in a manner such that it is more acidic than the pH conditions in step (a). For example, in one embodiment, step (a) may be performed at a neutral pl-1, or a pl-l ranging from about 6 to about 8 and step (b) may be performed at an acidic pH, e.g.. a pl-1 ranging from about 1 to about 5.
[00147] In another embodiment, step (b) comprises altering the salt concentration of the buffer in use, such that the target molecule is no longer bound to the l igand. For example, in one embodiment, a high salt concentration, e.g., > 0. 1 M. may be used in step (a) and a lower salt concentration, e.g.. <0. I M may be used in step (b). Conversely, in some embodiments, a low salt concentration, e.g., < 0.1 M may be used in step (a) and a high salt concentration may be used in step (b). In stil l other embodiments, both the pl-1 and the salt concentration of the buffer may be altered between step (a) and step (b). [00148 ) One skilled in the art can readily determine the conditions suitable for binding a target molecule to a ligand, and thereby alter the conditions to disrupt the binding of the molecule to the ligand.
[001491 In general , it is contemplated that the ligands described herein can be used in any puri fication process or a purification process train where native SpA and recombinant SpA are typical ly used. I n other words, it is generally desirable to replace the native SpA (e.g., isolated from S. aureus) and recombinant SpA {e.g.. recombinantly expressed wrt SpA) in the current processes in the art with the ligands described herein, in order to reduce overall cost as well as mitigate the risk of potential ly immunogenic SpA fragments co-purifying with a potential therapeutic molecule.
[001 50] In some embodiments, the present invention relates to a method of purification of antibodies by affinity chromatography, where the method includes the following steps: contacting a process feed with an affinity chromatography matrix according to the invention in order to bind one or more antibodies in the feed; an optional wash step; adding a suitable elution buffer for releasing the bound antibodies from the matrix; and recovering the one or more antibodies from the eluaie. The affinity chromatography matrices described herein may also be used lor isolating antibodies from culture liquids, supernatants as well as fermentation broths. In case of fermentation broths, the use of affinity chromatography matrices enables the separation of antibodies from host cell proteins (HCPs), DNA. viruses, endotoxins, nutrients, one or more components of a cell culture medium, e.g.. antifoam agents and antibiotics, and product-related impurities, such as misfolded species and aggregates.
[001 51 ] In a speci fic embodiment, the feed is subjected to mechanical filtration before it is contacted with the affinity chromatography matrix described herein, and consequently the mobile phase is a clari fied cel l culture broth. Suitable conditions for adsorption are well known to those of skil l in the art.
[001 52] In another embodiment, the present invention relates to a multi-step process for the purification of antibodies, which process comprises a capture step using an affinity chromatography matrix described herein followed by one or more subsequent steps for intermediate purification and/or polishing of the antibodies. In a particular embodiment, the capture step is followed by hydrophobic interaction and/or ion exchange chromatography and/or weak partition chromatography in bind-and elute or flow through mode. In an alternative step, the capture step is followed by multimodal anion or cation exchange chromatography and/or weak partition chromatography in bind-and-elute or flow through mode.
[00153] In another embodiment, any leached SpA-based ligand from the affinity chromatography matrix can be removed by the subsequent purification steps to acceptable levels e.g.. to levels deemed acceptable for native Protein A ligand.
[00154] In general, it is contemplated that the ligands described herein may be used in any process which typically employs Protein A ligands.
[00155] This invention is further illustrated by the following examples which should not be construed as limiting. The contents of all references, patents and published patent applications cited throughout this application, as well as the Figures, are incorporated herein by reference.
Examples
Example 1 : Generation of SnA Ligands With One or More Domains Having an
N-terniinus Deletion of 4 consecutive amino acids
[00156] Synthetic genes encoding the following proteins were obtained from
DNA 2.0 ( enlo Park, CA). A SpA dimeric protein containing two Z domains, each domain containing the mutation at position 29 (A29K) to reduce or eliminate Fab binding (amino acid sequence shown in SEQ ID NO: 85): and a SpA dimeric protein containing two Z domains, each domain containing the A29 mutation and the second Z domain containing a deletion to delete 4 consecutive amino acids from the N-terminus (amino acid sequence shown in SEQ ID NQ:78).
[00157] The 5' end of each synthetic gene includes a codon for an initialing methionine and the ?r end includes six histidine codons (SEQ I'D NO:86) for subsequent purification using NiNTA column. The 5!and 3 ' ends of each gene contain Ndel and BamHI restriction sites, respectively. These synthetic genes as well as the expression vector that is used, Le., pETI l a.(EMD). are digested with Ndel and BamHI (NEW ENGLAND BIOLABS, Ipswich, MA), the DNA fragments are separated on a 0.7 % agarose TAE gel and the appropriate DNA fragments are excised and purified using the gel extraction kit from QI AGEN (Valencia, CA). The purified inserts are ligated into the backbone of a pETI l a or any other suitable expression vector using T4 DNA ligase (NEW ENGLAND BIOLABS, Ipswich, MA). [001 58] The ligation reaction is transformed into DH5a competent E. coli
(I VITROG EN, Carlsbad. CA). as per manufacturer's instructions, and plated on Technova LB plates containing 100 ng mL ampicillin and grown overnight at 37°C. In order to obtain puri fied D A, individual colonies are picked for overnight culture in LB containing 100 n /mL ampicillin. DNA is purified using spin mini-prep kits from QIAGEN (Valencia, CA). The identity of recombinant plasmids is confirmed by restriction digest analysis using Ndel and BamHI (NEW ENGLAND BIOLA BS, Ipswich, MA). Plasmid maps for the plasmids including both inserted genes for the Z domain dimeric constructs are shown in Figure 2.
[00159 J Additionally, constructs expressing a pentameric form of SpA ligand containing 5 Z domains, each domain containing the A29 mutation (amino acid sequence set forth in SEQ I D NO:9 l ); as well as a pentameric form of SpA ligand containing 5 Z domains, with each domain containing the A29 mutation as well as all but the first domains containing a deletion of 4 consecutive amino acids from the N-ierminus (amino acid sequence set forth in SEQ ID NO:84), are generated.
[00160] Further, dimeric SpA ligand constructs containing C domains are also generated. A dimeric construct expressing a C domain ligand is generated, the amino acid sequence of which is set forth in SEQ ID NO:92; as well as a dimeric construct expressing a 2 C domain ligand is generated, where only the second C domain includes a deletion of 4 consecutive amino acids from the N-terminus, the amino acid sequence of which is set forth in SEQ I D NO:35. These C domain dimeric ligands do not have a mutation at position 29.
Example 2: Expression and Purification of SpA-Based Liquids
[00161 ] As discussed above, any suitable bacterial expression system can be used for expressing the various SpA l igands described herein. For example, the protein may be expressed in an Esc erchia coli strain such as strain BL21 (DE3) (PRO MEG A, Madison Wl) using a pET vector such as pETl l a (EMD).
[00162] A single colony is selected from a plate and grown overnight at 37°C in LB media containing 1 00 ng/mL ampicil lin. The overnight culture is di luted 1 00- fold into fresh LB media containing 1 00 g/mL ampicil l in and grown to a cell density such that the optical density at 600 nm is ~0.8. Following the addition of I mM isopropyl-beia-D-thiogalactopyraiioside, cells are grown for an additional two hours. Expression is confirmed by SDS-PAGE analysis and Western blotting.
[001631 Cells are harvested by centrifugation (4000 rpm, 4°C, 5 minutes) and restispended in 3 mL of phosphate buffered saline containing 20mM imidazole. Cells are lysed by sonication, and cell debris is pelleted by centrifugation (4000 rpm, 4 °C. 30 minutes). SpA ligands are purified using NiNTA resin (QIAGEN), applying 25-30 mL cell lysate per 3-mL column. Columns are washed with .30 mL phosphate buffered saline containing 20mM imidazole twice, and SpA is el u ted. in 3 mL fractions of phosphate buffered saline containing 200mM imidazole. SpA is dialyzed overnight into 18 mega-O m Milli-Q® water (MILLIPORE, Billerica,. MA) followed by l OmM NaHCOj. Protein concentration is confirmed using the UV spectrometer based on theoretical extinction coefficient (Pace el. uL, Protein Science 4:241 1 (1995)).
Example 3: Attachment of SpA-based Ligands to a Solid Support
[00164] Subsequent to the generation and expression of various ligands, as described in Examples I and 2, they were immobilized via multipoint attachment.to a solid support.
[001651 In an exemplary experiment, agarose resin (Sepharose 4B) (GE
HEALT HCARE) is crosslinked using epichlorohydrin according to a previously described method (Porath and Fornstecll, ./. Chromatography., 51 :479 ( 1979)). The agarose resin is subsequently reacted with positively charged associative groups, e.g., cations, according to the following method: to 10 mL of resin. 5 mL of 75 % wt glycidyl trimeihylammonium chloride (GTMAC), 5 mL Milli-Q© water
(MI LLIPORE, Billerica, MA) and 0.258 g 50 % wt sodium hydroxide is added. The reaction vial is rotated in a Techne HB- 1 D hybridizer (BIBB Y SCIENTIFIC, Burlington. NJ) overnight at room temperature. The resin is then filtered and washed with three 10-mL volumes of Milli-Q© water (MILLIPORE, Billerica, M A).
[00166] The resin ( 10 mL, filtered cake) is added to a jar containing 3 mL of
4.6M NaOH. The mixture is slurried and then 4 mL of butanediol diglycidylether (BUDGE) is added. This mixture is rotated at 35 °C for about 2 hours. The resin is then washed with 5x 10 mL of Milli-Q© water (MILLIPORE, Billerica, MA) and equilibrated with 2x 10 mL of l OmM NaH"C03. [00167] Immediately following the BUDG E activation step above, to 5 ni L of the filtered bead cake. 10 niL solution of l m NaHCOj containing a 2.5 and 2.3 iiig/mL concentration of dimeric Z domain ligand containing A29K. mutation (SEQ I D:85) or the dimeric Z domain ligand containing -terminus deletion in the second Z domain (SEQ I D:78), is added. The mixture is capped in a glass vial and the vial is rotated at 37 °C for about 2 hours. After two hours, the resin is washed with 3 times with 10 ml., of illi-Q® water. The filtered bead cake ( 10 niL) is added to a jar containing a 10 mL solut ion comprised of 1 mL of ihioglycerol and 9 niL of a buffer sol ution with 0.2M NaHCOj and 0.5M NaCl. The mixture is slurried and rotated overnight at room temperature. The resin is then washed with 3 times with 10 m L of the followin buffers: O. l M Tris buffer with 0. 1 5M NaCl (pH 8) and 50mM acetic acid (pl l 4.5). This is followed by rinsing the resin with 10 mL of Milli-Q® water and 1 0 mL of 20% cthanol water solution (v/v). The final resin is stored in 20% alcohol water solution (v/v) before further use. The method of coupling the dimeric C domain ligands to a solid support is similar to what is described herei n for the dimeric Z domain ligands.
1001 68] Method of coupling of 5 domain ligands described above (SEQ I D
NOs: 1 and 84) to agarose base resin is simi lar to the process above, except that 1 mg/niL of ligand is used during the coupling step. The Z domain pentameric ligands do not contain a His-6 lag.
Example 4: SDS-PAG E Analysis of Sunernatants Collected After Caustic Soak of Free or I mmobilized Ligands
[001 6 1 SDS-PAGE analysis can be used for detecting fragmentation of free and immobil ized ligands described herein, following extended caustic exposure. An SDS-PAG E protocol is described below.
[001 70] . SpA in Mi ll i-Q® water, neutralized caustic soaked l igand solution, and neutralized resin soak solutions (each contains -0.5 mg/mL of protein) are diluted at 1 : 1 ratio with Laemmli buffer (BIORAD. Hercules, CA). Samples are incubated at 70°C lor 5 minutes to ensure proteins were fully denatured. 10 ,uL of each sample is loaded to Any D gel (B I ORAD, Hercules, CA) or 1 5% Tris-HCI Ready gel
(BIORAD. Hercules. CA). Gel electrophoresis is conducted in I X Tris-Glycine-S DS running buffer (THERMOFISHER, VValtham, MA) at 200 volts for 30 minutes. SDS- Gel is then stained in Gelcode Blue stain reagent (TH ERMOFISHER. Wailham, MA) for 1 hour and dcstained in M illi-Q® water overnight.
Example 5: SEC Analysis of Supcrnatants Collected After Caustic Soak of
Free or I mmobilized Liuands
1001 71 ] In addition to SDS-PAGE analysis described above, SEC (size exclusion chromatography) can also be used for fragmentation analysis of the free and immobilized ligands following extended caustic soak. An SEC experiment is described below.
[001 72] SEC is conducted on an Agilent 1 1 00 H PLC system (AG I LENT.
Santa Clara. CA). SpA control in Mil li-Q® water, neutralized caustic soaked ligand solution (-0.5 mg/mL), and neutralized resin soak solutions are centri fuged at 13500 RPM for 10 minutes prior to SEC-HPLC analysis. Samples are injected in 20 μΙ. onto the S EC column (SEPAX Zenix 7.8 mm X 300mm, SEPAX TECHNOLOGIES, INC. Newark. Delaware). Sodium phosphate buffer (200mM, pU 7.0) is used as mobile phase with flow rate of 1 mL/min. ChemStation software from Agilent is used for SEC data acquisition and analysis at both 230 nm and 280 nm.
Example 6: Caustic Soak of Ligands
[001 73] Following the expression of the ligands, as described in Example 2. the ligands are exposed to alkaline conditions.
[001 74] To 1 niL of each of the ligands described above (at a concentration of
1 mg/mL), I niL of 1 NaOI I is added to a final concentration of 0.5M NaOI I and 0.5 mg/mL ligand. The sample is gently rotated for 25 hrs. This solution is then neutralized to pH ~ 7 using 32 pL of glacial acet ic acid.
[001 75] The fragmentation analysis of the Z domain and C domain dimeric ligands using SDS-PAGE following with and without caustic soak, is shown in Figure 3. As observed in Figure 3. the dimeric Z domain ligand (A29K with no deletions, shown in S EQ ID NO:85, w hich is used as the control) show s significant
fragmentation following caustic soak in 0.5M NaOI I for 25 hours, as demonstrated by the presence of a smear as well as presence of smal ler fragments at around 7 Da (see Lane 3). I n contrast, the dimeric Z domain ligand having the A29 mutation as well as a deletion oi' 4 consecutive amino acids in the second domain (amino acid sequence of SEQ I D O:78) appears to be largely intact following caustic soak in 0.5M NaOH for 25 hours (see Lane. 6).
[00176] Similarly, the dimeric C domain ligand having no deletions (the amino acid sequence set forth in SEQ ID NO: 2. used as a control) shows the presence of a . smear as well as smaller fragments around 7 KDa on an SDS-PAGE following caustic soak in 0.5M NaOH for 25 hours (see Lane 9) relative to the dimeric C domain construct which includes a deletion of 4 consecutive amino acid deletion from the N-terminus of the second domain, the amino acid sequence of which is set forth in SEQ ID NO:35 (see Lane 12).
[00177] Each of the dimeric Z and C domain ligands additionally includes a
His-6 tag. The ligands that are not exposed to caustic soak are shown in Lane 2 (dimeric Z domain control), Lane 5 (dimeric Z domain ligand having a N-terminus deletion). Lane 8 (dimeric C domain control) and Lane 9 (dimeric C domain ligand having a N-lerminus deletion).
[00178].. Reduced fragmentation of the dimeric Z and C domain ligands having an N-terminus deletion, following extended caustic soak, is further evidenced by SEC. The results of a representative- SEC experiment are shown in Figure 4. in the. form of an S EC chromatogram. As seen in Figure 4, the controls for the Z domain ligand (having the amino acid sequence set forth in SEQ ID NO:85) as well as the C domain ligand (having the amino acid sequence set forth in SEQ ID NO:92) show significant fragmentation, identified by arrows on the chromatogram in Figure 4. In contrast, the dimeric Z and C domain ligands having the N-terminus deletions in the second domain (Z domain ligand amino acid sequence is set forth in SEQ ID NO:78 and the C domain ligand amino acid sequence is set forth in SEQ ID NO:35), show reduced fragmentation, as identified by boxes on the chromatogram in Figure 4.
[0 1 79] Additionally, the pentameric forms of Z domain ligands described above (i.e.. pentameric Z domain ligand having the amino acid sequence of SEQ ID NO:91 which represents the control, and pentameric. Z domain ligand having the amino acid sequence of SEQ ID NO:84, which represents the pentameric ligand having a 4 consecutive amino acid N-lerminus deletion in all but the first domain) are also analyzed for fragmentation by SDS-PAGE, following caustic soak in 0.5M NaOH for 25 hours.
[00180] As evidenced by the SDS-PAGE gel data seen in Figure 5. the pentameric form of the Z domain ligand having a 4 consecutive amino acid deletion from the N-terminus in all but the first domain (the amino acid sequence of which is set forth in SEQ I D NO:84). shows far less fragmentation following ligand soak in 0.5 NaOH for 25 hours (see Lane 3), relative to the pentameric Z domain ligand control, the amino acid sequence of which is set forth in SEQ ID NO:91 (see Lane 6). As discussed above, both forms of pentameric ligands have the A29K mutation. The ligands that are not soaked appear to be intact (Lanes 2. and 5).
100181 ] Lanes 8- 10 depict the fragmentation observed with a recombinant
SpA ligand (rSPA). which is routinely used in purification processes. The rSPA ligand appear to show an even far greater degree of Iragmcntation following caustic soak in 0.5M NaOH for 25 hours relative to the Z domain control, as observed by a near disappearance of the protein on the SDS-PAGE (see Lane 9). The rSPA ligand not exposed to caustic conditions is in Lane 8.
[001821 This result appears to suggest that the Z domain based ligands having the N-lerminiis deletion, as described herein, are far superior candidates than the routinely used SpA ligands such as, <¾>.,. rSPA.
[00183 J A reduction in fragmentation following caustic soak in 0.5M NaOl I for 25 hours observed with the pentameric Z domain ligand having the N-terminal deletion is further confirmed using SEC, the results of one such representative experiment are shown in Figure 6.
[00184] As demonstrated by the chromatogram in Figure 6, the pentameric form of the Z domain control (SEQ ID NO: 1) with no amino acid deletion shows well resolved peaks at lower molecular weight, indicating the presence of smaller fragments. In contrast, the pentameric form of the Z domain having the N-terminus deletion (SEQ ID NO:84) shows significantly fewer distinct peaks at lower intensity, indicating a far less degree of fragmentation, relati ve to the control.
[001851 The routinely used SPA ligand, rSPA. shows the most fragmentation or breakdown with no intact molecule left at all. Notably, the SEC chromatogram is consistent with the results of the SDS-PAGE analysis in Figure 5, further evidencing that the rSPA ligand has degraded so much that no significant fragments can be observed on an SEC chromatogram following extended exposure to caustic conditions ( .c, soaking in 0.5M NaOH for 25 hours). Example 7: Caustic Soak of Ligands I m mobilized On Resin
[00186] The various ligands described in the foregoing examples are evaluated for fragmentation following caustic exposure subsequent to their attachment to a solid support (e.g.. an agarose chromatography resin).
| 00187] For each resin of interest, I mL resin in 5 niL disposable
chromatography column (EVERGREEN SCIENTIFIC. Los Angeles. CA) is measured using Milli-Q® water. The resin is conditioned in a column with 2 CV (2 mL) of 0.5M NaOH quickly, re-si urried and vacuumed. After repeating the NaOH condition one more time, the vacuumed wet cake of resin is transferred to 4 mL test tubes (THERMOFISHER, Waitham, MA). 2 mL of 0.5M NaOH is added to the column (bottom is capped) and immediately transferred into the test tube with the corresponding resin. Place capped test tubes onto a rotator and rotate the test tubes for 25 hrs. At the end of the caustic soak, content in the test tubes is poured into a disposable column and the filtrate is collected. Filtrate in 1 .5 mL is neutralized with 50 μί of glacial acidic acid and is ready for further analysis by SEC and SDS-PAGE.
[00188] The SDS-PAGE analysis of the immobilized dimeric Z and C domain ligands following extended caustic soak (e.g., 0.5M NaOH soak for 25 hours) is shown in Figure 3. In general, it is expected that if a ligand is caustic stable following its immobilization onto a chromatography matrix (e.g., an agarose resin), that it will .not show any significant fragmentation.
[00189] As observed by the SDS-PAGE gel of Figure 3: both the dimeric Z and C domain ligands immobilized controls (amino acid sequences set forth in SEQ ID NO:85 and 92. respectively and represented by Lanes 4 and 10 of the SDS-PAGE gel. respectively) as well as the dimeric Z and C domain immobilized ligands containing an N-terminus deletion in the second domain (amino acid sequences set forth in SEQ ID NO:78 and 35, respectively and represented by Lanes 7 and 1 3, respectively), do not appear to show any delectable fragmentation following 0.5M NaOH soak for 25 hours, implying that they are both caustic stable.
[00190] The SDS-PAGE analysis of the immobilized pentameric Z domain ligands following extended caustic soak (e.g.. 0.5M NaOH soak for 25 hours) is shown in Figure 5. As observed by the SDS-PAGE gel in Figure 5, the pentameric Z domain ligand containing an N-terminus deletion in all but the first domain (amino acid sequence set forth in SEQ ID NO:84. and represented by Lane 4 of the SDS- PAGE gel), shows far less fragmentation as compared to its type wt pentameric Z domain control (SEQ I D NO:91 and Lane 7). This result suggests that the immobilized pentameric Z domain ligand having the N-terminus deletions is more caustic stable compared to the immobilized pentameric Z domain which does not have such deletions.
[00191 1 Further, the fragmentation of a routinely used ligand (i.e.. rSPA) is also investigated by SDS-PAGE following its immobilization on an agarose chromatography resin and subjecting the resin with the ligand to an extended soak in 0.5 NaOH for 25 hours. As seen in Lane 10 of the SDS-PAGE gel of Figure 5, the immobilized rSPA shows significant fragmentation following 0.5M NaOH soak for 25 hours, implying that it is not very caustic stable, relative to the pentameric Z domain ligands (Lanes 4 and 7).
[00192] Based on the SDS-PAGE gel results on Figure 5. it can be concluded that the immobilized pentameric Z domain ligand. with the N-terminus deletions has the least fragmentation following extended caustic exposure;, and therefore, is most caustic stable, as compared to the immobilized pentameric Z'domain control ligand and the immobilized rSPA.
[00193] Further confirmation of the SDS-PAGE results with the immobilized pentameric Z domain ligands and the r-SPA ligand is obtained by SEC analysis. The results of a representative experiment are depicted in the chromatogram shown in Figure 7. As seen in Figure 7, the immobilized Z domain ligand of SEQ ID NO:84 shows reduced fragmentation following extended caustic soak, as shown by a box, relative to its. wl counterpart of SEQ ID NO:9 l , which shows resolved lower molecular weight peaks on the chromatogram. Further, as expected, the immobilized rSPA shows extensive fragmentation, following extended caustic soak as observed by broad and unresolved peaks on the chromatogram.
Example 8: Measurement of Static Binding Capacity of Chromatography
Matrices to an Immunoglobulin before and after exposure to 0.5M NaOH for 25 hours
[00194] The affinity chromatography matrices (i.e.. resins having the immobilized resins thereon w / multipoint attachment) described above are further tested for their static binding capacity before and after exposure to 0.5M NaOH for 25 hours. [00195] In one experiment, each of the chromatography matrices (in 1 mL volume) immobilized with the dimeric or pentameric 2 or C domain ligands described above, either with exposure to 0. 1 , 0.3 or 0.5M NaOH or without exposure to NaOH, is made into 10% slurry in ivlilli-Q® water (Ml LLIPORE, Billerica. MA). I mL of each slurry is added to 15 m L of polyclonal I G (SERACARE. 1 mg/niL)) in 10mN4 phosphate saline buffer and rotated for 4 hours at room temperature. The reduction of U V at 280 inn is used to calculate capacity before and after caustic binding capacity. The percentage of retained IgG binding capacity is calculated by dividing the IgG binding capacity after caustic exposure by that without caustic exposure. Table I I summarizes the results of one such experiment. As summarized in Table 11, the dimeric Z domain ligand of SEQ ID NO:78 appears to exhibit a higher retained binding capacity relative to its wt counterpart (i.e., the dimeric Z domain ligand of SEQ ID NO:85),. following extended caustic soak in 0.5M NaOH for 25 hours.
[001 6] Similarly, as also summarized in Table. II below, the dimeric C * domain ligand of SEQ I D NO:35 appears to exhibit a higher retained binding capacity than its wt counterpart of SEQ ID NO:92, following extended caustic soak in 0.5M NaOH for 25 hours.
Table II
Sequence of Ligand Retained IgG static binding
immobilized on matrix capacity of matrix (%)
SEQ ID NO: 85 ' 64
SEQ ID NO: 78 70
SEQ ID NO: 92 65
SEQ ID NO: 35 70
[00197] In a further experiment, the IgG binding capacity of a pentameric Z domain ligand is evaluated following extended caustic soak in 0.1 M NaOH, 0.3M NaOH or 0.5M NaOH for 25 hours. The results of one such experiment are summarized in Table III below.
[001981 Table HI shows the percentage of retained IgG binding capacity of a matrix having immobilized thereon a pentameric form of Z domain ligand which contains an A29K mutation and all but the first domain include a deletion of four consecutive amino acids from the N-terminus (amino acid sequence shown in SEQ ID NO: 84), after soaking the matrix in 0.1 M NaOH, 0.3 M NaOH or Q.5M NaOH. As summarized below, the matrix with the pentameric Z domain N-terminus deletion iigand shows up lo 95% of the initial binding capacity after 0.1 NaOH soak for 25 hours; up to 85% of the initial binding capacity after 0.3. NaOH soak for 25 hours and up to 65% of the initial binding capacity a ter 0.5M NaOH soak for 25 hours.
NaOH concentration (M) Retained IgG static binding capacity of
matrix immobilized with SEQ ID 84 (%)
0.1 95
0.3 85
0.5 65
Example 9: SpA capture of'TgG Before and After Exposure to 0.5M NaOH
[001 9] In this experiment, puri ication of a polyclonal immunoglobulin in null CHO-S feed using a matrix immobilized with a pentamer of Z domain ligand with all but the first domain having a 4 consecutive amino acid deletion is examined along with that having a recombinant!)' synthesized SpA (rSPA) in order to demonstrate that the ligancls according to the present invention work just as well as the recombinant SpA in removing impurities.
[002001 Resin samples immobilized with rSPA (REPUGEN Waltham, MA), and the Z domain peniameric ligand (amino acid sequence shown in SEQ ID 0.84). are each packed into a chromatography column with 1 cm diameter and 5 cm packed bed height. After equilibration with phosphate saline buffer ("1 OmM sodium phosphate)., the packed resins are subjected to exposure of null CHO feed with polyclonal hlgG (SERACARE, 5 mg/mL) at a flow rate of 50 cm/hr. After loading at 90 % of 5 % breakthrough, the resin is washed with PBS buffer and 50mM NaOAc, pH 5.5. The bound IgG is subsequently eluted with 50mM NaOAc, pl l 3. Fractions are collected and analyzed for impurity analysis. The packed resin is then exposed to 0.5M NaOH for 15 minutes (flow rale 100 cm/hr) before contacting again with polyclonal hlgG in null CHO feed. Resins are then washed with PBS buffer and 50mM NaOAc, pM 5.5 and IgG is eluted for further assay.
[00201 1 This caustic exposure and feed run cycle is repeated to collect enough IgG for the subsequent cation exchange step. Leached protein A is quantified using n-Protein A ELISA (REPLIGEN. Waltham. MA) according to instructions from the manufacturer. Host cell protein is detected using the 3G CHO HCP ELISA kit (CYGNUS TECHNOLOGIES, Southport. NC), as per the manufacturer s instructions. DNA is detected using Quant-iT™ PicoGreen ® dsDNA Reagent (LI FE TECH NOLOG IES, Foster City. CA). The results of one such representative experiment are shown in Table I V.
Ex simple 10: Clearance of Leached SpA Ligands and Further Removal of DNA and Host Cell Protein using Cation Exchange and Anion Exchange Chromatography
[002021 The clearance of the leached ligands as well as further removal of host cell proteins (HC ) and DMA from the elution pool of chromatography affinity matrices incorporating ei ther the SpA ligands according to the present invention or those containing recombinant SpA, rSPA (REPLIGEN. Waltham, MA), is examined as follows.
[00203] Combination of elut ion pool from several repetitions of the experiment described in Example 8 provides the feed for further clearance of leached l igands and other impurities using cation exchange chromatography.
[00204J Fractogel S03 " (M I LLIPORE, Billerica, MA) is packed into a column with bed dimension of 1 .0 cm (i.d.) x 7 cm (bed height). The column is equil ibrated with 50mM NaOAc pH 4.5, 4 mS/cm and loaded with the pooled IgG from Protein A elution at 140 cm/hr. After column wash with EQ buffer, IgG is eluted with 0.5N NaCI in 50mM NaOAc over 20 column volume (linear gradient). The elution pools are collected in 10 mL fractions and analyzed for leached ligands, DNA, and host cell protein.
[00205] The fractions from Fractolgel SO.v column are further pooled and adjusted to pl-1 7.6 at 1 2 mS/cm. This feed is loaded onto a pre-equilibrated (Tris. 25mM, pl-I 7.6, -I mS/cm) ChromaSorb device (0.08 mL. MI LLI PORE, Billerica, MA) at (low rate ol' 1 mL/min. Fractions are collected for every 1 87 column volume and further analyzed for leached ligand and host cell protein, as described in Example 8.
[00206] As summarized in Table IV below, both the leached rSPA l igand as well as the pentameric form of Z domain with all but the first domain having a ,N- terminus deletion of four consecutive amino acids (amino acid sequence set forth in SEQ I D:84). can be cleared to less than 1 PPM after cation exchange and anion exchange chromatography. In addition, the removal of host cel l proteins and DNA meets industry standard and is more or less equivalent in both cases, as also summarized in Table below. Table IV
Ligand on resin rS A SEQ I D: 84
Leached Protein A Protei A pool 7.1 3.8
(PPM) Cation exchange pool 1 .1 1.1
Anion exchange pool(@ 0.6 1.0 l g/mL loading)
Host cell proteins Feed 25568 25568
(PPM) Protein A pool 232 133
Cation exchange pool 49 60
Anion exchange pool 7
(@ l g/mL loading)
DNA (PPM) Feed 6.8 6.8
Protein A pool 0.05 0.04
Cation exchange pool 0.03 0.03
Anion exchange pool(@ Below Below
I g/mL loading) detection limit detection limit
Example 11 : Effect of the Number of N-terminus Amino Acid Deletions on
Fragmentation of Ligand Following Extended Caustic Soak
[00207] In another experiment, 1. 2, 3 or 4 amino acid residues were deleted from the N-terminus of the second domain of a dimeric Z domain ligand, starting at position 1. and the effect of the 1. 2. 3 or 4 amino acid deletions on the fragmentation of the ligand following extended caustic soak was determined, as compared to the control dimeric Z domain ligand (A29 )
[00208] The results of one such experiment are depicted in the chromatogram shown in Figure 8. As demonstrated in Figure 8, the effect on fragmentation of the number of amino acid residues that were deleted from the N-terminus of the second domain of the dimeric Z domain ligand can be observed following extended caustic soak of each of the ligands in 0.5M NaOH for 25 hours followed by SEC analysis, as described in Example 5.
[00209] After soaking the ligands in 0.5M NaOH for 25 hours, each of the control ligand (SIEQ ID NO:85), the ligand with only the first amino acid deleted from the N-terminus of the second domain (SEQ ID NO:87). and the ligand with the first two amino acids deleted from the N-terminus of the second domain (SEQ ID NO:88) shows fragments at lower molecular weight, as depicted by the arrows, evidencing fragmentation. Whereas, the ligand with the first three amino acids deleted from the N-terminus of the second domain (SEQ I D NO:69) and the ligand with the first four amino acids deleted from the N-terminus of the second domain (SEQ ID NO:78) showed significantly reduced fragmentation at lower molecular weight as depicted by boxes in the chromatogram. evidencing a reduced fragmentation.
[00210] These results suggest that the affinity ligands based on one or more domains of Protein A and having at least 3 amino acids deleted from the N-terminus of one or more domains exhibit reduced fragmentation following extended caustic exposure and accordingly, are superior candidates for use as affinity chromatography ligands.
Example 12: Retained Binding Capacity Comparison of N-terminus Deletion and Wild Type C domain pentamcrs, both having a non-Fab mutation (G29K)
[002 I I ] In this experiment, the retained binding capacity of two C domain pentameric ligands immobilized onto a polyvinyl alcohol based chromatography matrix is exami ned, one ligand having an N-terminus deletion (starting at position 1 ) of 4 amino acids in each of the 5 domains, an alanine as the very first amino acid of the pentameric sequence in order to faci litate homogeneous post-translational processing as well as the G29K mutation (the amino acid sequence of which is shown in SEQ ID NO:93) and the other ligand corresponding to its wt counterpart with the G29K mutation (the amino acid sequence of which is shown in SEQ ID NO:95).
[00212] The ligands are immobilized onto polyvinyl alcohol based affinity chromatography resins via multipoint attachment (see, e.g., 1-lermanson el al., Immobilized Affinity Ligand Techniques, Academic Press, pp. 5 1 - 1 36 ( 1 92)), and tested tor retained dynamic binding capacity upon repeated NaOH exposure.
[00213] In one experiment, the chromatography matrices are packed into col umns (0.66 cm i.d. x 1 .0 cm bed height) and are subjected to a standard chromatographic run with equilibration fol lowed by application of 30 mg polyclonal human IgG (hlgG) at 60 cni/hr. After extensive washing-out of unbound proteins with equilibration buffer ( l Om phosphate buffer saline), bound IgG is eluted with elulion buffer (0.1 M citric acid, pH 3) at 60 cm/hr. This is followed by Cleaning-In- Place (CI P) with 0.7 NaOH for 30 mins. The column is re-equi librated and the run is repeated for 16 more times (a cumulative exposure to 0.7M NaOH for 8 hi s). Retained binding capacity is measured by determining total amount of eluted IgG (elulion volume multiplied by IgG concentration measured at UV2so) over time. Relative retained capacity is plotted against the first run with 0 min exposure to NaOH and is shown in Figure 9. This experiment is repeated 3 times with similar results. As demonstrated in Figure 9. both C domain pentameric ligands, with and without the deletion, show similar retained binding capacity following extended exposure to NaO.H over time. Further, in another experiment., retained binding capacity of the C domain pentameric ligand without the alanine and having the G29K mutation (amino acid sequence of which is shown in SEQ ID NO:80) is compared to its wt counterpart with the G29 mutation (amino acid seciuence of which is shown in SEQ I D NO:95). with a simi lar result (data not shown).
[00214] The specification is most thoroughly understood in l ight of the teachings of the references cited within the specification which are hereby incorporated by reference. The embodiments within the specification provide an illustration of embodiments in this invention and should not be construed to limit its scope. The skilled artisan readi ly recognizes that many other embodiments are encompassed by this invention. All publications and inventions are incorporated by reference in their entirety. To the extent that the material incorporated by reference contradicts or is inconsistent with the present specification, the present speci fication wil l supercede any such material. The citation of any references herein is not an admission that such references are prior art to the present invention.
[0021 5] Unless otherwise indicated, all numbers expressing quantities of ingredients, cell culture, treatment conditions, and so forth used in the speci fication, including claims, are to be understood as being modified in all instances by the term "about." Accordingly, unless otherwise indicated to the contrary, the numerical parameters are approximations and may vary depending upon the desired properties sought to be obtained by the present invention. Unless otherwise indicated, the term "at least" preceding a series of elements is to be understood to refer to every element in the series. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.
[002 16] Many modifications and variations of this invention can be made without departing from its spirit and scope, as will be apparent to those ski lled in the art. The specific embodiments described herein are offered by way of example only and are not meant to be limiting in any way. It is intended that the speci fication and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims

What is claimed is:
1 . An affinity chromatography ligand comprising one or more C domains of Staphylococcus Protein A (SpA), wherein at least one C domain comprises a delet ion of at . least 3 consecutive amino acids from the N-terminus, starting at position 1 or position 2.
2. An affinity chromatography ligand comprising one or more B domains of Staphylococcus Protein A (SpA). wherein at least one B domain comprises a deletion of at least 3 consecutive amino acids from the N-terminus, starting at position 1 or position 2.
3. An affinity chromatography ligand comprising one or more Z domains of Staphylococcus Protein A (SpA). wherein at least one Z domain comprises a deletion of at least 3 consecutive amino acids from the N-terminus, starting at position 1 or position 2.
4. The affinity chromatography ligand according to claim I , 2 or 3. wherein the ligand exhibits reduced fragmentation, relative to a wt counterpart, following exposure to 0.5M NaOH for at least 5 hours.
5. An affinity chromatography matrix comprising an affinity chromatography ligand according to claim 1 , 2 or 3 attached to a solid support.
6. The affinity chromatography matrix of claim 5. wherein the ligand exhibits reduced fragmentation when attached to the solid support, relative lo a wt counterpart, following exposure to 0.5M NaOH for 5 hours.
7. The affinity chromatography ligand according to claim 1. 2, or 3, wherein one or more domains of the ligand further comprise an amino acid mutation at position 29 to reduce Fab binding.
8. The affinity chromatography ligand of claim 7, wherein the amino acid mutation comprises replacing a glycine amino acid residue or an alanine amino acid residue with a lysine amino acid residue.
9. The affinity chromatography matrix of claim 5, wherein affinity
chromatography ligand is attached to the solid support via multipoint attachment.
10. The affinity chromatography ligand according to claim I , wherein the affinity chromatography ligand comprises two, three, four, five, six, seven or more C domains of Staphylococcus Protein A (SpA), wherein at least one C domain
comprises a deletion of three consecutive amino acids from the N-terminus or a
deletion of four consecutive amino acids from the N-terminus or a deletion of five consecutive amino acids from the N-terminus. starling at position I or at position 2.
1 1 . The affinity chromatography ligand according to claim 3. wherein the affinity chromatography l igand comprises two, three, four, five, six, seven or more Z domains of Staphylococcus Protein A (SpA), wherein at least one Z domain
comprises a deletion of three consecutive amino acids from the N-terminus or a deletion of four amino acids from the N-terminus or a deletion of five consecutive amino acids from the N-terminus, starting at position 1 or at position 2.
12. The affinity chromatography ligand according to claim 2. wherein the affinity ligand comprises two. three, four, five, six. seven or more B domains of
Staphylococcus Protein A (SpA). wherein at least one B domain comprises a deletion of three consecutive amino acids from the N-terminus or a deletion of four amino acids from N-lerminus or a deletion of five consecutive amino acids from the N- terminus. starting at position 1 or at position 2.
1 3. A method of affinity purifying one or more target molecules from a sample, the method comprising the steps of:
(a) providing a sample comprising one or more target molecules;
(b) contacting the sample- with the matrix of claim 5 under conditions such that the one or more target molecules bind to the matrix: and
(c) recovering the one or more bound target molecules by edition.
14. The affinity chromatography matrix of claim 5, wherein the matrix retains at least 95% of its initial binding capacity after 5 hours incubation in 0.5M NaOH.
1 5. The affini ty chromatography matrix of claim 5, wherein the matrix retains at least 95% of ils initial binding capacity after 25 hours incubation in 0.1 NaOH.
1 6. An affinity ligand comprising the structure:
Figure imgf000060_0001
where X represents a B domain, a Z domain or a C domain of SpA,
n represents the number of domains ranging from zero through (m- 1 ),
Y represents a B domain or a Z domain or a C domain of SpA having at least 3 consecutive amino acids deleted from the N-terminus, and
m represents the number of Y domains ranging from one through eight, where the ligand is attached to a solid support via multipoint attachment.
1 7. An affinity chromatography ligand comprising two or more B domains of SpA or two or more C domains of SpA or two or more Z domains of SpA. or any combinations of B, Z or C domains in any order, wherein at least one of B, C or Z domains comprises a deletion of at least 3 amino acids from the N-terminus. starting at position 1 or at position 2.
1 8. The affinity chromatography ligand of claim 1 7, wherein the ligand exhibits reduced fragmentation relative to a ligand without any deletions, fol lowing exposure to 0.5M NaOH for 5 hours.
1 . The affinity chromatography matrix according to claim 5 or claim 9. wherein the solid support is selected from the group consisting of controlled pore glass, silica, zirconium oxide, titanium oxide, agarose, polymethacrylate, polyacrylate. polyacrylainide. polvvinylether. polyvinyl alcohol and polystyrene and derivatives thereof .
20. An alkaline stable affinity chromatography ligand comprising at least five C domains, wherein each of the domains comprises a mutation to reduce Fab binding as well as deletion of 4 amino acids from the N-terminus. starting at position 1 .
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