Methods for Producing Fabs and IgG Bispecific Antibodies
Methods for producing Fabs and IgG bi-specific antibodies comprising expressing nucleic acids encoding designed residues in the CH1/CL interface are provided. Also provided are Fabs and IgG bi-specific antibodies produced according to the provided methods as well as nucleic acids, vectors and host cells encoding the same.
This application is a continuation of U.S. patent application Ser. No. 16/465,689 filed May 31, 2019, which is the US National Stage of International Application No. PCT/US2017/066296 filed Dec. 14, 2017, which claims the benefit of U.S. Provisional Application No. 62/437,740 filed Dec. 22, 2016. The foregoing applications are incorporated herein by reference.
SEQUENCE LISTINGThe instant application contains a Sequence Listing which has been submitted electronically in XML file format and is hereby incorporated by reference in its entirety. Said XML copy, created on Oct. 10, 2023, is named X20936_44P06WOUS2_SL.xml and is 128,840 bytes in size.
BACKGROUNDBispecific antibodies integrate the binding properties of two distinct antigen binding proteins into a single molecule. Bispecific antibodies represent an alternative to the co-formulation and/or co-administration of separate antibody agents or fragments, when the therapeutic targeting of multiple antigens or epitopes is desired. In addition, bispecific antibodies may elicit synergistic activities beyond that of an antibody combination. For example, bispecific antibodies could be used to bridge different cell types through binding of distinct cell surface receptors, thus facilitating, for example, the targeting of immune cells to tumor cells. Alternately, bispecific antibodies could cross-link and/or cluster separate cell surface signaling receptors to elicit novel mechanisms of action.
The archetypical IgG antibody is a hetero-tetramer comprised of two identical heavy chains (HC) and two identical light chains (LC). Each HC associates with a separate LC to form two identical antigen binding fragments (Fabs) via assembly interfaces between the HC and LC variable domains (the VH/VL interface) and the HC constant CH1 and LC constant domains (the CH1/CL interface.) Once formed, each Fab directs the binding of the IgG antibody to the same antigenic determinant. As a consequence of their modular nature, numerous formats have been proposed for generating IgG-derived bispecific antibodies. Examples include, diabodies, IgG-single chain variable fragments (IgG-scFv), dual variable domain-IgG (DVD-IgG), Fab-Fab, and IgG-Fab. However, many of these formats alter the native IgG antibody geometry and its resulting stability and solubility, and/or require extensive engineering to stabilize component variable domains outside of the native Fab context.
Recently, methods have been described for generating bispecific antibodies retaining the full IgG antibody architecture by co-expressing nucleic acids encoding two distinct HC-LC pairs containing designed mutations in the CH1/CL and/or VH/VL interfaces which, when expressed, provide improved assembly of a fully IgG antibody comprising two distinct Fabs. (See Lewis, et al. (2014), Nat. Biotechnol., 32; 191-198; and Published PCT Applications WO2014/150973 and WO2014/0154254) In addition, procedures for directing assembly of particular HC-HC pairs by introducing modifications into regions of the HC-HC interface to promote improved HC heterodimerization have also been disclosed in the art (See Leaver-Fay A., et al. (2016), Structure; 24; 641-651; Klein et al., mAbs; 4(6); 1-11 (2012); Carter et al., J. Immunol. Methods; 248; 7-15 (2001); Gunasekaran, et al., J. Biol. Chem.; 285; 19637-19646 (2010); Zhu et al., Protein Sci.; 6: 781-788 (1997); and Igawa et al., Protein Eng. Des. Sel.; 23; 667-677 (2010)). However, there yet remains a need for alternative methods for generating fully IgG BsAbs.
SUMMARYIn accordance with the present invention, further methods have been identified for achieving assembly of distinct Fabs by co-expressing nucleic acids encoding particular HC-LC pairs which contain designed residues in the CH1/CL interface. More particularly, the methods of the present invention achieve improved correct assembly and good stability of particular Fabs containing kappa LC constant domains (Cκ). Even more particular, the methods of the present invention allow the binding activities of Fabs of two distinct therapeutic antibodies to be combined in a single fully IgG bi-specific antibody compound. Further, the designs and methods of the present invention may be combined with other known methods for improving HC-LC specific assembly, and/or HC-HC heterodimerization, thus further facilitating assembly of fully IgG BsAbs.
Thus, the present invention provides a method for producing a first and second fragment, antigen binding (Fab) comprising: (1) co-expressing in a host cell: (a) a first nucleic acid sequence encoding both a first heavy chain variable domain and a first human IgG heavy chain constant CH1 domain, wherein said first human IgG heavy chain constant CH1 domain comprises an alanine substituted at (or an alanine at) residue 145; (b) a second nucleic acid sequence encoding both a first light chain variable domain and a first human light chain kappa constant domain, wherein said first human light chain kappa constant domain comprises an arginine substituted at (or an arginine at) residue 131; (c) a third nucleic acid encoding both a second heavy chain variable domain and a second human IgG heavy chain constant CH1 domain, wherein said second human IgG heavy chain constant CH1 domain is the WT sequence; and (d) a fourth nucleic acid encoding both a second light chain variable domain and a second human light chain kappa constant domain, wherein said second human light chain kappa constant domain is the WT sequence, wherein each of said first heavy chain and light chain variable domains comprise three complementarity determining regions (CDRs) which direct binding to a first antigen and further wherein each of said second heavy chain and light chain variable domains comprise three complementarity determining regions (CDRs) which direct binding to a second antigen that differs from said first antigen; (2) cultivating said host cell under conditions such that said first and second heavy chain variable and human IgG CH1 constant domains and said first and second light chain variable and human kappa constant domains are produced; and (3) recovering from said host cell a first and second Fab wherein said first Fab comprises said first heavy chain variable and human IgG constant CH1 domains and said first light chain variable and human kappa constant domains, and said second Fab comprises said second heavy chain variable and human IgG constant CH1 domains and said second light chain variable and human kappa constant domains. More particular to this embodiment, the present invention provides a method wherein said first human IgG heavy chain constant CH1 domain further comprises a glutamic acid substituted at (or a glutamic acid at) residue 221 and said first human light chain kappa constant domain further comprises a lysine substituted at (or a lysine at) residue 123. Even more particular to either of the afore-mentioned embodiments, the present invention provides a method wherein, said first human IgG heavy chain constant CH1 domain further comprises an alanine or glycine substituted at (or an alanine or glycine at) residue 188 and said first human light chain kappa constant domain further comprises an isoleucine substituted at (or an isoleucine at) residue 176.
As another embodiment, the present invention provides a method for producing a first and second fragment, antigen binding (Fab) comprising: (1) co-expressing in a host cell: (a) a first nucleic acid sequence encoding both a first heavy chain variable domain and a first human IgG heavy chain constant CH1 domain, wherein said first human IgG heavy chain constant CH1 domain comprises an alanine substituted at (or an alanine at) residue 145 and an alanine or glycine substituted at (or an alanine or glycine at) residue 188; (b) a second nucleic acid sequence encoding both a first light chain variable domain and a first human light chain kappa constant domain, wherein said first human light chain kappa constant domain comprises an arginine substituted at (or an arginine at) residue 131 and an isoleucine substituted at (or an isoleucine at) residue 176; (c) a third nucleic acid encoding both a second heavy chain variable domain and a second human IgG heavy chain constant CH1 domain, wherein said second human IgG heavy chain constant CH1 domain comprises a glutamic acid substituted at (or a glutamic acid at) residue 221; and (d) a fourth nucleic acid encoding both a second light chain variable domain and a second human light chain kappa constant domain, wherein said second human light chain kappa constant domain comprises a lysine substituted at (or a lysine at) residue 123, wherein each of said first heavy chain and light chain variable domains comprise three complementarity determining regions (CDRs) which direct binding to a first antigen and further wherein each of said second heavy chain and light chain variable domains comprise three complementarity determining regions (CDRs) which direct binding to a second antigen that differs from said first antigen; (2) cultivating said host cell under conditions such that said first and second heavy chain variable and human IgG CH1 constant domains and said first and second light chain variable and human kappa constant domains are produced; and (3) recovering from said host cell a first and second Fab wherein said first Fab comprises said first heavy chain variable and human IgG constant CH1 domains and said first light chain variable and human kappa constant domains, and said second Fab comprises said second heavy chain variable and human IgG constant CH1 domains and said second light chain variable and human kappa constant domains.
The CH1/Cκ interface designs of the methods as described above may also be combined with designs in VH/VL interface as described in Lewis et al. (2014) and WO2014/150973. Thus, as another particular embodiment, the present invention provides any of the afore-mentioned methods wherein: (a) said first heavy chain variable domain comprises a glutamic acid substituted at (or a glutamic acid at) the residue which is four amino acids upstream of the first residue of HFR3 according to Kabat Numbering and a lysine substituted at (or a lysine at) residue 39; (b) said first light chain variable domain is kappa isotype and comprises an arginine substituted at (or an arginine at) residue 1 and an aspartic acid substituted at (or an aspartic acid at) residue 38; (c) said second heavy chain variable domain comprises a tyrosine substituted at (or a tyrosine at) residue 39 and an arginine substituted at (or an arginine at) residue 105; and (d) said second light chain variable domain is kappa isotype and comprises an arginine substituted at (or an arginine at) residue 38 and an aspartic acid substituted at (or an aspartic acid at) residue 42. Alternately, the present invention provides any of the afore-mentioned methods wherein: (a) said first heavy chain variable domain comprises a tyrosine substituted at (or a tyrosine at) residue 39 and an arginine substituted at (or an arginine at) residue 105; (b) said first light chain variable domain is kappa isotype and comprises an arginine substituted at (or an arginine at) residue 38 and an aspartic acid substituted at (or an aspartic acid at) residue 42; (c) said second heavy chain variable domain comprises a glutamic acid substituted at (or a glutamic acid at) the residue which is four amino acids upstream of the first residue of HFR3 according to Kabat Numbering and a lysine substituted at (or a lysine at) residue 39; and (d) said second light chain variable domain is kappa isotype and comprises an arginine substituted at (or an arginine at) residue 1 and an aspartic acid substituted at (or an aspartic acid at) residue 38.
Even more particular, the present invention provides any of the afore-mentioned methods wherein each of said first and second human IgG heavy chain constant CH1 domains are individually IgG1 or IgG4 isotype. The present invention also provides any of the afore-mentioned methods wherein each of said first and second human IgG heavy chain constant CH1 domains are IgG1 isotype. The present invention also provides any of the afore-mentioned methods wherein each of said first and second human IgG heavy chain constant CH1 domains are IgG4 isotype.
Further still, the present invention provides any of the afore-mentioned methods wherein: (a) said first human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:67), said first human light chain kappa constant domain amino acid sequence is (SEQ ID NO:57), said second human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO: 66), and said second human light chain kappa constant domain amino acid sequence is (SEQ ID NO:2); or (b) said first human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:68), said first human light chain kappa constant domain amino acid sequence is (SEQ ID NO:59), said second human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:69), and said second human light chain kappa constant domain amino acid sequence is (SEQ ID NO:61); or (c) said first human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:70), said first human light chain kappa constant domain amino acid sequence is (SEQ ID NO:59), said second human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:69), and said second human light chain kappa constant domain amino acid sequence is (SEQ ID NO:61); or (d) said first human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO: 71), said first human light chain kappa constant domain amino acid sequence is (SEQ ID NO: 64), said second human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:66), and said second human light chain kappa constant domain amino acid sequence is (SEQ ID NO:2); or (e) said first human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:72), said first human light chain kappa constant domain amino acid sequence is (SEQ ID NO: 64), said second human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:66), and said second human light chain kappa constant domain amino acid sequence is (SEQ ID NO:2).
Further, the present invention provides any of the afore-mentioned methods wherein each of said first and second light chain variable domains is human kappa isotype.
The present invention also provides a method for producing an IgG bispecific antibody comprising: (1) co-expressing in a host cell: (a) a first nucleic acid sequence encoding both a first heavy chain variable domain and a first human IgG heavy chain constant region, wherein said first human IgG heavy chain constant region comprises a CH1 constant domain comprising an alanine substituted at (or an alanine at) residue 145; (b) a second nucleic acid sequence encoding both a first light chain variable domain and a first human light chain kappa constant domain, wherein said first human light chain kappa constant domain comprises an arginine substituted at (or an arginine at) residue 131; (c) a third nucleic acid encoding both a second heavy chain variable domain and a second human IgG heavy chain constant region, wherein said second human IgG heavy chain constant region comprises a CH1 constant domain that is the WT sequence; and (d) a fourth nucleic acid encoding both a second light chain variable domain and a second human light chain kappa constant domain, wherein said second human light chain kappa constant domain is the WT sequence, wherein each of said first heavy chain and light chain variable domains comprise three complementarity determining regions (CDRs) which direct binding to a first antigen and further wherein each of said second heavy chain and light chain variable domains comprise three complementarity determining regions (CDRs) which direct binding to a second antigen that differs from said first antigen; (2) cultivating said host cell under conditions such that said first and second heavy chain variable and human IgG CH1 constant domains and said first and second light chain variable and human kappa constant domains are produced; and (3) recovering from said host cell an IgG bispecific antibody comprising a first and second fragment, antigen binding (Fab) wherein said first Fab comprises said first heavy chain variable and human IgG constant CH1 domains and said first light chain variable and human kappa constant domains, and said second Fab comprises said second heavy chain variable and human IgG constant CH1 domains and said second light chain variable and human kappa constant domains. More particular to this embodiment, the present invention provides a method for producing an IgG bispecific antibody wherein said first human IgG heavy chain constant CH1 domain further comprises a glutamic acid substituted at (or a glutamic acid at) residue 221 and said first human light chain kappa constant domain further comprises a lysine substituted at (or a lysine at) residue 123. Even more particular to either of the afore-mentioned embodiments, the present invention provides a method for producing an IgG bispecific antibody wherein, said first human IgG heavy chain constant CH1 domain further comprises an alanine or glycine substituted at (or an alanine or glycine at) residue 188 and said first human light chain kappa constant domain further comprises an isoleucine substituted at (or an isoleucine at) residue 176.
As another embodiment, the present invention provides a method for producing an IgG bispecific antibody comprising: (1) co-expressing in a host cell: (a) a first nucleic acid sequence encoding both a first heavy chain variable domain and a first human IgG heavy chain constant region, wherein said first human IgG heavy chain constant region comprises a CH1 constant domain comprising an alanine substituted at (or an alanine at) residue 145 and an alanine or glycine substituted at (or an alanine or glycine at) residue 188; (b) a second nucleic acid sequence encoding both a first light chain variable domain and a first human light chain kappa constant domain, wherein said first human light chain kappa constant domain comprises an arginine substituted at (or an arginine at) residue 131 and an isoleucine substituted at (or an isoleucine at) residue 176; (c) a third nucleic acid encoding both a second heavy chain variable domain and a second human IgG heavy chain constant region, wherein said second IgG heavy chain constant region comprises a CH1 domain comprising a glutamic acid substituted at (or a glutamic acid at) residue 221; and (d) a fourth nucleic acid encoding both a second light chain variable domain and a second human light chain kappa constant domain, wherein said second human light chain kappa comprises a lysine substituted at (or a lysine at) residue 123, wherein each of said first heavy chain and light chain variable domains comprise three complementarity determining regions (CDRs) which direct binding to a first antigen and further wherein each of said second heavy chain and light chain variable domains comprise three complementarity determining regions (CDRs) which direct binding to a second antigen that differs from said first antigen; (2) cultivating said host cell under conditions such that said first and second heavy chain variable and human IgG CH1 constant domains and said first and second light chain variable and human kappa constant domains are produced; and (3) recovering from said host cell an IgG bispecific antibody comprising a first and second Fab wherein said first Fab comprises said first heavy chain variable and human IgG constant CH1 domains and said first light chain variable and human kappa constant domains, and said second Fab comprises said second heavy chain variable and human IgG constant CH1 domains and said second light chain variable and human kappa constant domains.
The CH1/Cκ interface designs of the methods for producing an IgG bispecific antibody, as described above, may also be combined with designs in VH/VL interface as described in Lewis et al. (2014) and WO2014/150973. Thus, as another embodiment, the present invention provides any of the afore-mentioned methods for producing an IgG bispecific antibody wherein: (a) said first heavy chain variable domain comprises a glutamic acid substituted at (or a glutamic acid at) the residue which is four amino acids upstream of the first residue of HFR3 according to Kabat Numbering and a lysine substituted at (or a lysine at) residue 39; (b) said first light chain variable domain is kappa isotype and comprises an arginine substituted at (or an arginine at) residue 1 and an aspartic acid substituted at (or an aspartic acid at) residue 38; (c) said second heavy chain variable domain comprises a tyrosine substituted at (or a tyrosine at) residue 39 and an arginine substituted at (or an arginine at) residue 105; and (d) said second light chain variable domain is kappa isotype and comprises an arginine substituted at (or an arginine at) residue 38 and an aspartic acid substituted at (or an aspartic acid at) residue 42. Alternately, the present invention provides any of the afore-mentioned methods for producing an IgG bispecific antibody wherein: (a) said first heavy chain variable domain comprises a tyrosine substituted at (or a tyrosine at) residue 39 and an arginine substituted at (or an arginine at) residue 105; (b) said first light chain variable domain is kappa isotype and comprises an arginine substituted at (or an arginine at) residue 38 and an aspartic acid substituted at (or an aspartic acid at) residue 42; (c) said second heavy chain variable domain comprises a glutamic acid substituted at (or a glutamic acid at) the residue which is four amino acids upstream of the first residue of HFR3 according to Kabat Numbering and a lysine substituted at (or a lysine at) residue 39; and (d) said second light chain variable domain is kappa isotype and comprises an arginine substituted at (or an arginine at) residue 1 and an aspartic acid substituted at (or an aspartic acid at) residue 38.
The CH1/Cκ interface designs of the methods for producing an IgG bispecific antibody, as described above, may also be combined with designs in CH3/CH3 interface as described in Leaver-Fay A., et al. (2016), Structure; 24; 641-651 and WO 2016/118742 A1. Thus, as a further particular embodiment, the present invention provides any of the afore-mentioned methods for producing an IgG bispecific antibody wherein: (a) one of said first or second human IgG constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407; and the other of said first or second human IgG constant regions comprises a CH3 domain comprising a valine substituted at (or a valine at) residue 366 and a valine substituted at (or a valine at) residue 409; or (b) one of said first or second human IgG constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407 and a methionine substituted at (or a methionine at) residue 399; and the other of said first or second human IgG constant regions comprises a CH3 domain comprising a valine substituted at (or a valine at) residue 366 and a valine substituted at (or a valine at) residue 409; or (c) one of said first or second human IgG constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407, a methionine substituted at (or a methionine at) residue 399, and an aspartic acid substituted at (or an aspartic acid at) residue 360; and the other of said first or second human IgG constant regions comprises a CH3 domain comprising a valine substituted at (or a valine at) residue 366, a valine substituted at (or a valine at) residue 409, and an arginine substituted at (or an arginine at) residues 345 and 347; or (d) one of said first or second human IgG constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407, an aspartic acid substituted at (or an aspartic acid at) residue 357, and a glutamine substituted at (or a glutamine at) residue 364; and the other of said first or second human IgG constant regions comprises a CH3 domain comprising a valine substituted at (or a valine at) residue 366, a valine substituted at (or a valine at) residue 409, a serine substituted at (or a serine at) residue 349, and a tyrosine substituted at (or a tyrosine at) residue 370; or (e) one of said first or second human IgG constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407, an aspartic acid substituted at (or an aspartic acid at) residue 357, and a glutamine substituted at (or a glutamine at) residue 364; and the other of said first or second human IgG constant regions comprises a CH3 domain comprising a methionine substituted at (or a methionine at) residue 366, a valine substituted at (or a valine at) residue 409, a serine substituted at (or a serine at) residue 349, and a tyrosine substituted at (or a tyrosine at) residue 370; or (f) one of said first or second human IgG constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407, an aspartic acid substituted at (or an aspartic acid at) residue 357, and an arginine substituted at (or an arginine at) residue 364; and the other of said first or second human IgG constant regions comprises a CH3 domain comprising a valine substituted at (or a valine at) residue 366, a valine substituted at (or a valine at) residue 409, a serine substituted at (or a serine at) residue 349, and a tyrosine substituted at (or a tyrosine at) residue 370; or (g) one of said first or second human IgG constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407, a glycine substituted at (or a glycine at) residue 356, an aspartic acid substituted at (or an aspartic acid at) residue 357, and a glutamine substituted at (or a glutamine at) residue 364; and the other of said first or second human IgG constant regions comprises a CH3 domain comprising a valine substituted at (or a valine at) residue 366, a valine substituted at (or a valine at) residue 409, a serine substituted at (or a serine at) residue 349, and a tyrosine substituted at (or a tyrosine at) residue 370; or (h) one of said first or second human IgG constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407, a glycine substituted at (or a glycine at) residue 356, an aspartic acid substituted at (or an aspartic acid at) residue 357, and a glutamine substituted at (or a glutamine at) residue 364; and the other of said first or second human IgG constant regions comprises a CH3 domain comprising a methionine substituted at (or a methionine at) residue 366, a valine substituted at (or a valine at) residue 409, a serine substituted at (or a serine at) residue 349, and a tyrosine substituted at (or a tyrosine at) residue 370; or (i) one of said first or second human IgG constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407, an aspartic acid substituted at (or an aspartic acid at) residue 357, and an arginine substituted at (or an arginine at) residue 364; and the other of said first or second human IgG constant regions comprises a CH3 domain comprising a methionine substituted at (or a methionine at) residue 366, a valine substituted at (or a valine at) residue 409, a serine substituted at (or a serine at) residue 349, and a tyrosine substituted at (or a tyrosine at) residue 370.
As yet another embodiment, the present invention provides any of the afore-mentioned methods for producing an IgG bispecific antibody wherein each of said first and second human IgG heavy chain constant regions are individually IgG1 or IgG4 isotype, and more particularly each are IgG1, or each are IgG4.
Further still, the present invention provides any of the afore-mentioned methods for producing an IgG bispecific antibody wherein: (a) said first human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO: 67), said first human light chain kappa constant domain amino acid sequence is (SEQ ID NO:57), said second human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:66), and said second human light chain kappa constant domain amino acid sequence is (SEQ ID NO:2); or (b) said first human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:68), said first human light chain kappa constant domain amino acid sequence is (SEQ ID NO:59), said second human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:69), and said second human light chain kappa constant domain amino acid sequence is (SEQ ID NO:61); or (c) said first human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:70), said first human light chain kappa constant domain amino acid sequence is (SEQ ID NO: 59), said second human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:69), and said second human light chain kappa constant domain amino acid sequence is (SEQ ID NO:61); or (d) said first human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:71), said first human light chain kappa constant domain amino acid sequence is (SEQ ID NO: 64), said second human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:66), and said second human light chain kappa constant domain amino acid sequence is (SEQ ID NO:2); or (e) said first human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:72), said first human light chain kappa constant domain amino acid sequence is (SEQ ID NO:64), said second human IgG heavy chain constant CH1 domain amino acid sequence is (SEQ ID NO:66), and said second human light chain kappa constant domain amino acid sequence is (SEQ ID NO:2).
As a further particular embodiment, the present invention provides any of the afore-mentioned methods for producing an IgG bispecific antibody wherein: (a) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:83); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:78); or (b) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:74); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:78); or (c) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:75); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:79); or (d) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:76); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:80); or (e) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:77); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:80); or (f) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:76); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:82); or (g) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:76); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:81); or (h) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:77); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:81); or (i) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:77); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:82).
Further, the present invention provides any of the afore-mentioned methods for producing an IgG bispecific antibody wherein each of said first and second light chain variable domains is human kappa isotype.
The present invention also provides an IgG bispecific antibody comprising: (a) a first heavy chain, wherein said first heavy chain comprises a first variable domain (VH) and a first human IgG1 or IgG4 constant region, wherein said first human IgG1 or IgG4 constant region comprises an alanine substituted at (or an alanine at) residue 145 of the CH1 domain; (b) a first light chain, wherein said first light chain comprises a first variable domain (VL) and a first human light chain kappa constant domain (Cκ), wherein said first human light chain kappa constant domain comprises an arginine substituted at (or an arginine at) residue 131; (c) a second heavy chain, wherein said second heavy chain comprises a second variable domain (VH) and a second human IgG1 or IgG4 constant region, wherein said second human IgG1 or IgG4 heavy chain constant region comprises a CH1 constant domain that is the WT sequence; and (d) a second light chain, wherein said second light chain comprises a second variable domain (VL) and a second human light chain kappa constant domain (Cκ), wherein said second human light chain kappa constant domain is the WT sequence, wherein each of said first heavy chain and light chain variable domains comprise three complementarity determining regions (CDRs) which direct binding to a first antigen and further wherein each of said second heavy chain and light chain variable domains comprise three complementarity determining regions (CDRs) which direct binding to a second antigen that differs from said first antigen. More particular to this embodiment, the present invention provides an IgG bispecific antibody wherein said first human IgG1 or IgG4 heavy chain constant region CH1 domain further comprises a glutamic acid substituted at (or a glutamic acid at) residue 221 and said first human light chain kappa constant domain further comprises a lysine substituted at (or a lysine at) residue 123. Even more particular to either of the afore-mentioned embodiments, the present invention provides an IgG bispecific antibody wherein said first human IgG1 or IgG4 heavy chain constant region CH1 domain further comprises an alanine or glycine substituted at (or an alanine or glycine at) residue 188 and said first human light chain kappa constant domain further comprises an isoleucine substituted at (or an isoleucine at) residue 176.
The present invention also provides an IgG bispecific antibody comprising: (a) a first heavy chain, wherein said first heavy chain comprises a first variable domain (VH) and a first human IgG1 or IgG4 constant region, wherein said first human IgG1 or IgG4 constant region comprises an alanine substituted at (or an alanine at) residue 145 and an alanine or glycine substituted at (or an alanine or glycine at) residue 188 of the CH1 domain; (b) a first light chain, wherein said first light chain comprises a first variable domain (VL) and a first human light chain kappa constant domain (Cκ), wherein said first human light chain kappa constant domain comprises an arginine substituted at (or an arginine at) residue 131 and an isoleucine substituted at (or an isoleucine at) residue 176; (c) a second heavy chain, wherein said second heavy chain comprises a second variable domain (VH) and a second human IgG1 or IgG4 constant region, wherein said second human IgG1 or IgG4 heavy chain constant region comprises a glutamic acid substituted at (or a glutamic acid at) residue 221 of the CH1 constant domain; and (d) a second light chain, wherein said second light chain comprises a second variable domain (VL) and a second human light chain kappa constant domain (Cκ), wherein said second human light chain kappa constant domain comprises a lysine substituted at (or a lysine at) residue 123, wherein each of said first heavy chain and light chain variable domains comprise three complementarity determining regions (CDRs) which direct binding to a first antigen and further wherein each of said second heavy chain and light chain variable domains comprise three complementarity determining regions (CDRs) which direct binding to a second antigen that differs from said first antigen.
The CH1/Cκ interface designs of the IgG bispecific antibodies as described above may also be combined with designs in VH/VL interface as described in Lewis et al. (2014) and WO2014/150973. Thus, as another embodiment, the present invention provides any of the afore-mentioned IgG bispecific antibodies wherein: (a) said first heavy chain variable domain comprises a glutamic acid substituted at (or a glutamic acid at) the residue which is four amino acids upstream of the first residue of HFR3 according to Kabat Numbering and a lysine substituted at (or a lysine at) residue 39; (b) said first light chain variable domain is kappa isotype and comprises an arginine substituted at (or an arginine at) residue 1 and an aspartic acid substituted at (or an aspartic acid at) residue 38; (c) said second heavy chain variable domain comprises a tyrosine substituted at (or a tyrosine at) residue 39 and an arginine substituted at (or an arginine at) residue 105; and (d) said second light chain variable domain is kappa isotype and comprises an arginine substituted at (or an arginine at) residue 38 and an aspartic acid substituted at (or an aspartic acid at) residue 42. Alternately, the present invention provides any of the afore-mentioned IgG bispecific antibodies wherein: (a) said first heavy chain variable domain comprises a tyrosine substituted at (or a tyrosine at) residue 39 and an arginine substituted at (or an arginine at) residue 105; (b) said first light chain variable domain is kappa isotype and comprises an arginine substituted at (or an arginine at) residue 38 and an aspartic acid substituted at (or an aspartic acid at) residue 42; (c) said second heavy chain variable domain comprises a glutamic acid substituted at (or a glutamic acid at) the residue which is four amino acids upstream of the first residue of HFR3 according to Kabat Numbering and a lysine substituted at (or a lysine at) residue 39; and (d) said second light chain variable domain is kappa isotype and comprises an arginine substituted at (or an arginine at) residue 1 and an aspartic acid substituted at (or an aspartic acid at) residue 38.
The CH1/Cκ interface designs of the IgG bispecific antibodies, as described above, may also be combined with designs in CH3/CH3 interface as described in Leaver-Fay A., et al. (2016), Structure; 24; 641-651 and WO 2016/118742 A1. Thus, as a further particular embodiment, the present invention provides any of the afore-mentioned IgG bispecific antibodies wherein: (a) one of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407; and the other of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising a valine substituted at (or a valine at) residue 366 and a valine substituted at (or a valine at) residue 409; or (b) one of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407 and a methionine substituted at (or a methionine at) residue 399; and the other of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising a valine substituted at (or a valine at) residue 366 and a valine substituted at (or a valine at) residue 409; or (c) one of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407, a methionine substituted at (or a methionine at) residue 399, and an aspartic acid substituted at (or an aspartic acid at) residue 360; and the other of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising a valine substituted at (or a valine at) residue 366, a valine substituted at (or a valine at) residue 409, and an arginine substituted at (or an arginine at) residues 345 and 347; or (d) one of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407, an aspartic acid substituted at (or an aspartic acid at) residue 357, and a glutamine substituted at (or a glutamine at) residue 364; and the other of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising a valine substituted at (or a valine at) residue 366, a valine substituted at (or a valine at) residue 409, a serine substituted at (or a serine at) residue 349, and a tyrosine substituted at (or a tyrosine at) residue 370; or (e) one of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407, an aspartic acid substituted at (or an aspartic acid at) residue 357, and a glutamine substituted at (or a glutamine at) residue 364; and the other of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising a methionine substituted at (or a methionine at) residue 366, a valine substituted at (or a valine at) residue 409, a serine substituted at (or a serine at) residue 349, and a tyrosine substituted at (or a tyrosine at) residue 370; or (f) one of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407, an aspartic acid substituted at (or an aspartic acid at) residue 357, and an arginine substituted at (or an arginine at) residue 364; and the other of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising a valine substituted at (or a valine at) residue 366, a valine substituted at (or a valine at) residue 409, a serine substituted at (or a serine at) residue 349, and a tyrosine substituted at (or a tyrosine at) residue 370; or (g) one of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407, a glycine substituted at (or a glycine at) residue 356, an aspartic acid substituted at (or an aspartic acid at) residue 357, and a glutamine substituted at (or a glutamine at) residue 364; and the other of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising a valine substituted at (or a valine at) residue 366, a valine substituted at (or a valine at) residue 409, a serine substituted at (or a serine at) residue 349, and a tyrosine substituted at (or a tyrosine at) residue 370; or (h) one of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407, a glycine substituted at (or a glycine at) residue 356, an aspartic acid substituted at (or an aspartic acid at) residue 357, and a glutamine substituted at (or a glutamine at) residue 364; and the other of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising a methionine substituted at (or a methionine at) residue 366, a valine substituted at (or a valine at) residue 409, a serine substituted at (or a serine at) residue 349, and a tyrosine substituted at (or a tyrosine at) residue 370; or (i) one of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising an alanine substituted at (or an alanine at) residue 407, an aspartic acid substituted at (or an aspartic acid at) residue 357, and an arginine substituted at (or an arginine at) residue 364; and the other of said first or second human IgG1 or IgG4 constant regions comprises a CH3 domain comprising a methionine substituted at (or a methionine at) residue 366, a valine substituted at (or a valine at) residue 409, a serine substituted at (or a serine at) residue 349, and a tyrosine substituted at (or a tyrosine at) residue 370.
Even more particular, the present invention provides any of the afore-mentioned IgG bispecific antibodies wherein one of said first or second human IgG1 or IgG4 heavy chain constant regions is IgG1 isotype and the other of said first or second human IgG1 or IgG4 heavy chain constant regions is IgG4 isotype. The present invention also provides any of the afore-mentioned IgG bispecific antibodies wherein each of said first and second human IgG1 or IgG4 heavy chain constant regions are IgG1 isotype. The present invention also provides any of the afore-mentioned IgG bispecific antibodies wherein each of said first and second human IgG1 or IgG4 heavy chain constant regions are IgG4 isotype.
Further still, the present invention provides any of the afore-mentioned IgG bispecific antibodies wherein: (a) said first human IgG heavy chain constant region comprises a CH1 domain amino acid sequence that is (SEQ ID NO:67), said first human light chain kappa constant domain amino acid sequence is (SEQ ID NO:57), said second human IgG heavy chain constant region comprises a CH1 domain amino acid sequence that is (SEQ ID NO:66), and said second human light chain kappa constant domain amino acid sequence is (SEQ ID NO:2); or (b) said first human IgG heavy chain constant region comprises a CH1 domain amino acid sequence that is (SEQ ID NO:68), said first human light chain kappa constant domain amino acid sequence is (SEQ ID NO:59), said second human IgG heavy chain constant region comprises a CH1 domain amino acid sequence that is (SEQ ID NO:69), and said second human light chain kappa constant domain amino acid sequence is (SEQ ID NO:61); or (c) said first human IgG heavy chain constant region comprises a CH1 domain amino acid sequence that is (SEQ ID NO:70), said first human light chain kappa constant domain amino acid sequence is (SEQ ID NO:59), said second human IgG heavy chain constant region comprises a CH1 domain amino acid sequence that is (SEQ ID NO:69), and said second human light chain kappa constant domain amino acid sequence is (SEQ ID NO:61); or (d) said first human IgG heavy chain constant region comprises a CH1 domain amino acid sequence that is (SEQ ID NO:71), said first human light chain kappa constant domain amino acid sequence is (SEQ ID NO:64), said second human IgG heavy chain constant region comprises a CH1 domain amino acid sequence that is (SEQ ID NO: 66), and said second human light chain kappa constant domain amino acid sequence is (SEQ ID NO:2); or (e) said first human IgG heavy chain constant region comprises a CH1 domain amino acid sequence that is (SEQ ID NO:72), said first human light chain kappa constant domain amino acid sequence is (SEQ ID NO:64), said second human IgG heavy chain constant region comprises a CH1 domain amino acid sequence that is (SEQ ID NO:66), and said second human light chain kappa constant domain amino acid sequence is (SEQ ID NO:2).
As a further particular embodiment, the present invention provides any of the afore-mentioned IgG bispecific antibodies wherein: (a) one of said first or second human IgG constant regions comprises an Fe domain amino acid sequence that is (SEQ ID NO:83); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:78); or (b) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:74); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:78); or (c) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:75); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:79); or (d) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:76); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:80); or (e) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:77); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:80); or (f) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:76); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:82); or (g) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:76); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:81); or (h) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:77); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:81); or (i) one of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:77); and the other of said first or second human IgG constant regions comprises an Fc domain amino acid sequence that is (SEQ ID NO:82).
Further, the present invention provides any of the afore-mentioned IgG bispecific antibodies wherein each of said first and second light chain variable domains is human kappa isotype.
The present invention further provides a first and second Fab, or an IgG bispecific antibody produced accord to any one of the processes of the present invention. In addition to the preparation of Fabs and fully IgG BsAbs, the methods described herein may also be employed in the preparation of other multi-valent antigen binding compounds.
The present invention further provides nucleic acid sequences encoding the first and second heavy chains and the first and second light chains of any of the Fabs or IgG BsAbs of the present invention. In addition, the present invention also provides vectors comprising nucleic acid sequences encoding the first heavy chain, the first light chain, the second heavy chain and/or the second light chain of any of the Fabs or IgG BsAbs of the present invention. Further still, the present invention provides host cells comprising nucleic acid sequences encoding the first heavy chain, the first light chain, the second heavy chain and the second light chain of any of the Fabs or IgG BsAbs of the present invention.
The general structure of an “IgG antibody” is very well-known. A wild type (WT) antibody of the IgG type is hetero-tetramer of four polypeptide chains (two identical “heavy” chains and two identical “light” chains) that are cross-linked via intra- and inter-chain disulfide bonds. Each heavy chain (HC) is comprised of an N-terminal heavy chain variable region (“VH”) and a heavy chain constant region. The heavy chain constant region is comprised of three domains (CH1, CH2, and CH3) as well as a hinge region (“hinge”) between the CH1 and CH2 domains. Each light chain (LC) is comprised of an N-terminal light chain variable region (“VL”) and a light chain constant region (“CL”). The VL and CL regions may be of the kappa (“κ”) or lambda (“λ”) isotypes (“Cκ” or “Cλ”, respectively). Each heavy chain associates with one light chain via interfaces between the heavy chain and light chain variable domains (the VH/VL interface) and the heavy chain constant CH1 and light chain constant domains (the CH1/CL interface). The association between each of the VH-CH1 and VL-CL segments forms two identical antigen binding fragments (Fabs) which direct antibody binding to the same antigen or antigenic determinant. Each heavy chain associates with the other heavy chain via interfaces between the hinge-CH2-CH3 segments of each heavy chain, with the association between the two CH2-CH3 segments forming the Fc region of the antibody. Together, each Fab and the Fc form the characteristic “Y-shaped” architecture of IgG antibodies, with each Fab representing the “arms” of the “Y.” IgG antibodies can be further divided into subtypes, e.g., IgG1, IgG2, IgG3, and IgG4 which differ by the length of the hinge regions, the number and location of inter- and intra-chain disulfide bonds and the amino acid sequences of the respective HC constant regions.
The variable regions of each heavy chain-light chain pair associate to form binding sites. The heavy chain variable region (VH) and the light chain variable region (VL) can be subdivided into regions of hypervariability, termed complementarity determining regions (“CDRs”), interspersed with regions that are more conserved, termed framework regions (“FR”). Each VH and VL is composed of three CDRs and four FRs, arranged from amino-terminus to carboxy-terminus in the following order: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4. CDRs of the heavy chain may be referred to as “CDRH1, CDRH2, and CDRH3” and the 3 CDRs of the light chain may be referred to as “CDRL1, CDRL2 and CDRL3.” The FRs of the heavy chain may be referred to as HFR1, HFR2, HFR3 and HFR4 whereas the FRs of the light chain may be referred to as LFR1, LFR2, LFR3 and LFR4. The CDRs contain most of the residues which form specific interactions with the antigen. As used herein, “antigen” or “antigenic determinant” refers to a target protein to which an IgG antibody binds, or to a particular epitope (on a target protein) to which an IgG antibody binds.
As used herein, the terms “IgG bispecific antibody”, “IgG BsAb”, “fully IgG bispecific antibody” or “fully IgG BsAb” refer to an antibody of the typical IgG architecture comprising two distinct Fabs, each of which direct binding to a separate antigen or antigenic determinant (i.e., different target proteins or different epitopes on the same target protein), and composed of two distinct IgG heavy chains and two distinct light chains. The VH-CH1 segment of one heavy chain associates with the VL-CL segment of one light chain to form a “first” Fab, wherein the VH and VL domains each comprise 3 CDRs which direct binding to a first antigen. The VH-CH1 segment of the second heavy chain associates with the VL-CL segment of the second light chain to form a “second” Fab, wherein the VH and VL domains each comprise 3 CDRs which direct binding to a second antigen that is different than the first. More particularly, the terms “IgG bispecific antibody”, “IgG BsAb”, “fully IgG bispecific antibody” or “fully IgG BsAb” refer to antibodies wherein the HC constant regions are composed of CH1, CH2, and CH3 domains of the IgG1, IgG2 or IgG4 subtype, and particularly the human IgG1, human IgG2 or human IgG4. Even more particular, the terms refer to antibodies wherein the HC constant regions are composed of CH1, CH2, and CH3 domains of the IgG1 or IgG4 subtype, and most particularly the human IgG1 or human IgG4 subtype. In addition, as used herein, the terms “IgG bispecific antibody”, “IgG BsAb”, “fully IgG bispecific antibody” and “fully IgG BsAb” refer to an antibody wherein the constant regions of each individual HC of the antibody are all of the same subtype (for example, each of the CH1, CH2, and CH3 domains of a HC are all of the human IgG1 subtype, or each of the CH1, CH2, and CH3 domains of a HC are all of the IgG2 subtype, or each of the CH1, CH2, and CH3 domains of a HC are all of the IgG4 subtype.) Even more particular, the term refers to an antibody wherein the constant regions of both HCs are all of the same subtype (for example, both HCs have CH1, CH2, and CH3 domains of the human IgG1 subtype, or both HCs have CH1, CH2, and CH3 domains of the human IgG2 subtype, or both HCs have CH1, CH2, and CH3 domains of the human IgG4 subtype.)
The processes and compounds of the present invention comprise designed amino acid modifications at particular residues within the constant and variable regions of heavy chain and light chain polypeptides. As one of ordinary skill in the art will appreciate, various numbering conventions may be employed for designating particular amino acid residues within IgG constant and variable region sequences. Commonly used numbering conventions include the “Kabat Numbering” and “EU Index Numbering” systems. “Kabat Numbering” or “Kabat Numbering system”, as used herein, refers to the numbering system devised and set forth by the authors in Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed, Public Health Service, National Institutes of Health, Bethesda, MD (1991) for designating amino acid residues in both variable and constant domains of antibody heavy chains and light chains. “EU Index Numbering” or “EU Index Numbering system”, as used herein, refers to the numbering convention for designating amino acid residues in antibody heavy chain constant domains, and is also set forth in Kabat et al. (1991). Other conventions that include corrections or alternate numbering systems for variable domains include Chothia (Chothia C, Lesk A M (1987), J Mol Biol 196: 901-917; Chothia, et al. (1989), Nature 342: 877-883), IMGT (Lefranc, et al. (2003), Dev Comp Immunol 27: 55-77), and AHo (Honegger A, Pluckthun A (2001) J Mol Biol 309: 657-670). These references provide amino acid sequence numbering schemes for immunoglobulin variable regions that define the location of variable region amino acid residues of antibody sequences. Unless otherwise expressly stated herein, all references to immunoglobulin heavy chain variable region (i.e., VH), constant region CH1 and hinge amino acid residues (i.e. numbers) appearing in the Examples and Claims are based on the Kabat Numbering system, as are all references to the light chain VL and CL residues. All references to immunoglobulin heavy chain constant region CH2 and CH3 residues (i.e., numbers) are based on the EU Index Numbering system. Thus, as used herein, the phrase “(according to Kabat Numbering)” indicates that the recited amino acid residue number (or position) is numbered in accordance with the Kabat Numbering system, whereas the phrase “(according to EU Index Numbering)” indicates that the recited amino acid residue number (or position) is numbered in accordance with the EU Index Numbering system. With knowledge of the residue number according to Kabat Numbering or EU Index Numbering, one of ordinary skill can apply the teachings of the art to identify amino acid sequence modifications within the present invention, according to any commonly used numbering convention. Note, while the Examples and Claims of the present invention employ Kabat Numbering or EU Index Numbering to identify particular amino acid residues, it is understood that the SEQ ID NOs appearing in the Examples and Sequence Listing accompanying the present application, as generated by Patent In Version 3.5, provide sequential numbering of amino acids within a given polypeptide and, thus, do not conform to the corresponding amino acid residue numbers as provided by Kabat Numbering or EU Index Numbering.
However, as one of skill in the art will also appreciate, CDR sequence length may vary between individual IgG molecules and, further, the numbering of individual residues within a CDR may vary depending on the numbering convention applied. Thus, to reduce ambiguity in the designation of amino acid residues within CDRs, such amino acid residues may be identified by first employing Kabat Numbering to identify the N-terminal (first) amino acid residue of a reference FR (e.g., HFR3). The residue comprising the recited amino acid of the designs may then be denoted as being a fixed number of residues upstream (i.e. in the N-terminal direction) from the first amino acid residue in the reference FR (e.g., HFR3). For example, a Fab design used in combination with the CH1/Cκ domain designs of the present invention comprises the placement of a glutamic acid (E) in HCDR2 of a particular HC (i.e., Fab Design “AB” comprising glutamic acid at residue 62 (Kabat Numbering) as described in Lewis, et al. (2014)). The recited glutamic acid is located at the residue position four amino acids upstream of the first amino acid of HFR3, as determined according to Kabat Numbering. In the Kabat Numbering system, amino acid residue X66 is the most N-terminal (first) amino acid residue of variable region heavy chain framework three (HFR3). One of ordinary skill can employ such a strategy to identify the first amino acid residue (most N-terminal) of heavy chain framework three (HFR3) from any human IgG1, IgG2 or IgG4 antibody variable region. Once this landmark is identified, one can then locate the amino acid residue four residues upstream (N-terminal) to this location and replace that amino acid (using standard insertion/deletion methods) with a glutamic acid (E) to achieve the design of the invention. Thus, given any parental immunoglobulin heavy chain amino acid query sequence of interest to use in the processes of the invention, one of ordinary skill in the art of antibody engineering would be able to locate the N-terminal HFR3 residue (according to Kabat Numbering) in said query sequence and then count four amino acid residues upstream therefrom to arrive at the location in HCDR2 that should be a glutamic acid (E).
As used herein, the phrase “ . . . a/an [amino acid name] substituted at residue . . . ”, in reference to a heavy chain or light chain polypeptide, refers to substitution of the parental amino acid with the indicated amino acid. By way of example, a heavy chain comprising “a lysine substituted at residue 39” refers to a heavy chain wherein the parental amino acid sequence has been mutated to contain a lysine at residue number 39 in place of the parental amino acid. Such mutations may also be represented by denoting a particular amino acid residue number, preceded by the parental amino acid and followed by the replacement amino acid. For example, “Q39K” refers to a replacement of a glutamine at residue 39 with a lysine. Similarly, “39K” refers to replacement of a parental amino acid with a lysine. One of skill in the art will appreciate, however, that as a result of the interface design modifications of the present invention, Fab pairs and fully IgG BsAbs (and processes for their preparation) are therefore provided wherein the component HC and LC amino acid sequences comprise the resulting or “replacement” amino acid at the designated residue. Thus, for example, a heavy chain which “comprises a lysine substituted at residue 39” may alternatively be denoted simply as a heavy chain which “comprises a lysine at residue 39.”
As used herein, the phrase “WT” or “WT sequence”, in reference to a HC or LC amino acid residue or polypeptide chain, refers to the wild-type or native amino acid or sequence of amino acids that naturally occupies the residue or residues of the polypeptide chain indicated.
Preferably, an IgG BsAb (or Fab pair) of the present invention exists in a homogeneous or substantially homogeneous population. In an embodiment, the IgG BsAb, Fab, or a nucleic acid encoding a component polypeptide sequence of the IgG BsAb or Fab, is provided in “isolated” form. As used herein, the term “isolated” refers to a protein, polypeptide or nucleic acid which is free or substantially free from other macromolecular species found in a cellular environment.
An IgG BsAb or Fab pair of the present invention can be produced using techniques well known in the art, such as recombinant expression in mammalian or yeast cells. In particular, the methods and procedures of the Examples herein may be readily employed. In addition, the IgG BsAbs or Fabs of the present invention may be further engineered to comprise framework regions derived from fully human frameworks. A variety of different human framework sequences may be used in carrying out embodiments of the present invention. As a particular embodiment, the framework regions employed in the processes, as well as the IgG BsAbs and Fab pairs of the present invention are of human origin or are substantially human (at least 95%, 97% or 99% of human origin.) The sequences of framework regions of human origin are known in the art and may be obtained from The Immunoglobulin Factsbook, by Marie-Paule Lefranc, Gerard Lefranc, Academic Press 2001, ISBN 012441351.
Expression vectors capable of directing expression of genes to which they are operably linked are well known in the art. Expression vectors contain appropriate control sequences such as promoter sequences and replication initiation sites. They may also encode suitable selection markers as well as signal peptides that facilitate secretion of the desired polypeptide product(s) from a host cell. The signal peptide can be an immunoglobulin signal peptide or a heterologous signal peptide. Nucleic acids encoding desired polypeptides, for example the components of the IgG BsAbs of Fabs prepared according to the processes of the present invention, may be expressed independently using different promoters to which they are operably linked in a single vector or, alternatively, the nucleic acids encoding the desired products may be expressed independently using different promoters to which they are operably linked in separate vectors. In addition, nucleic acids encoding a particular HC/LC pair of the IgG BsAbs or Fabs of the present invention may expressed from a first vector, while the other HC/LC pair is expressed from a second vector. Single expression vectors encoding both HC and both LC components of the IgG BsAbs and Fabs of the present invention may be prepared using standard methods. By way of example, a pE vector encoding a particular HC/LC pair may be engineered to contain a NaeI site 5 prime of a unique SalI site, outside of the HC/LC expression cassette. The vector may then be modified to contain an AscI site 5 prime of the SalI site using standard techniques. For example, the NaeI to SalI region may be PCR amplified using a 3′ primer containing the AscI site adjacent to the SalI site, and the resulting fragment cloned into the recipient pE vector. The expression cassette encoding a second HC/LC pair, may then be isolated from a second (donor) vector by digesting the vector at suitable restriction sites. For example, the donor vector may be engineered with MluI and SalI sites to permit isolation of the second expression cassette. This cassette may then be ligated into the recipient vector previously digested at the AscI and SalI sites (as AscI and MluI restriction sites have the same overlapping ends.)
As used herein, a “host cell” refers to a cell that is stably or transiently transfected, transformed, transduced or infected with nucleotide sequences encoding a desired polypeptide product or products. Creation and isolation of host cell lines producing an IgG BsAb or Fab pair of the present invention can be accomplished using standard techniques known in the art.
Mammalian cells are preferred host cells for expression of the IgG BsAb and Fab compounds according to the present invention. Particular mammalian cells include HEK293, NS0, DG-44, and CHO cells. Preferably, assembled proteins are secreted into the medium in which the host cells are cultured, from which the proteins can be recovered and isolated. Medium into which a protein has been secreted may be purified by conventional techniques. For example, the medium may be applied to and eluted from a Protein A or G column using conventional methods. Soluble aggregate and multimers may be effectively removed by common techniques, including size exclusion, hydrophobic interaction, ion exchange, hydroxyapatite or mixed modal chromatography. Recovered products may be immediately frozen, for example at −70° C., or may be lyophilized. As one of skill in the art will appreciate, when expressed in certain biological systems, e.g. mammalian cell lines, antibodies are glycosylated in the Fc region unless mutations are introduced in the Fc to reduce glycosylation. In addition, antibodies may be glycosylated at other positions as well.
The object of the present invention is to provide orthogonal interfaces which promote the correct pairing of particular heavy chain Fab fragments (denoted, for example as HC_“A” and HC_“B”) with their cognate light chain Fab fragments (i.e., LC_“a” and LC_“b”) by introducing particular mutations into heavy chain CH1/light chain Cκ domain pairs. As a result of the present invention, increased correct assembly of “Aa” and “Bb” dimers is achieved, relative to the incorrectly assembled “Ab” or “Ba” dimers, when the individual heavy chain and light chain monomers (i.e., “A”, “B”, “a” and “b” chains) are concomitantly expressed in a host cell. The following Examples further illustrate the invention and provide typical methods and procedures for carrying out various particular embodiments of the present invention. However, it is understood that the Examples are set forth the by way of illustration and not limitation, and that various modifications may be made by one of ordinary skill in the art.
Example 1: Computational and Rational Design of Modifications of CH1/Cκ InterfaceThe identification and design of the particular CH1/Cκ residue mutations resulted from an iterative combination of computational and rational approaches. Starting from the high resolution crystal structure of the human IgG1 CH1/CG interface (PDB ID 4NZU from which variable domains are removed) heavy chain residues 122, 124, 139, 141, 143, 145, 174, 188, and 190 and light chain residues 116, 118, 124, 131, 133, 135, and 176 (all according to Kabat Numbering) are selected for initial mutation, allowing substitution to all amino acids except cysteine. Using the Rosetta multistate design (MSD) protocol, and related modeling applications, the resulting sequences are imposed on each of the four dimer and four monomer species to computationally identify potential modifications that favor correct “Aa” and “Bb” dimer formation.
Briefly, the MSD protocol in Rosetta explores sequence space, and for each sequence, calculates an energy for each of several “states” treating phenomena such as van der Waals force and hydrogen bonding forces. The “states” represent different combinations and/or conformations of the various species being modeled. MSD optimizes the sequence side chain conformations, without changing backbone conformations, and aggregates the energies into a fitness metric that reflects how well particular sequences meet design objectives. The fitness values then guide the search through sequence space, and sequences with improved fitness scores can be identified from the simulation. To facilitate the present designs, a fitness function is chosen that favors the binding energies of the correctly paired “Aa” and “Bb” dimers, while disfavoring the binding energies of the mis-paired “Ab” and “Ba” dimers.
To remove an artifact of the fixed-backbone simulation, the weight given to the destabilization of the mis-paired interactions is capped in the fitness function employed in the present methods. The fixed-backbone simulation has a limitation in that it blinds MSD to the possibility that collisions introduced across the interface for mis-paired interactions can be resolved by moving the backbone slightly. Such slight motions can be approximated, however, by using a repertoire of alternate conformations for the mis-paired interactions. A repertoire of alternate backbone conformations is generated by running MSD with only the backbone conformation from the 4NZU crystal structure to identify additional sequences, then feeding these sequences into rigid-body docking using RosettaDock (See Gray, J. J. et al. (2003), J. Mol. Biol.; 331; 281-299). Low-energy backbone conformations identified by rigid-body docking using the Rosetta Interface Analyzer tool. (See Lewis, S. M. & Kuhlman, B. A. (2011), PLoS One 6; e20872 and Stranges, P. B. & Kuhlman, B. A (2013), Protein Sci.; 22; 74-82) are then selected for the repertoire of alternate conformations. This process is iterated multiple times until the difference in measured binding energies following MSD simulation and rigid-body docking is small. After building a repertoire of alternate conformation, several hundred MSD simulations followed by several thousand rigid-body docking runs are performed to create a pool of sequences.
Sequences are selected for further analysis by the total energies and binding energies of the correctly paired interactions and the difference in binding energies between the correctly-paired and mis-paired interactions. These sequences are manually examined to identify frequently occurring pairs of mutations as well as other mutations that often accompany. The identified mutations are divided into multiple families, and within each family, all combinations of possible alternative mutations are enumerated. For each of these sequences, all four dimers are then run through Rosetta's “fast relax” protocol (See Tyka, M. D. et al. (2011), J. Mol. Biol.; 405; 607-618 and Khatib, F. et al. (2011), Proc. Natl. Acad. Sci.; 108; 18949-18953), which allows backbone flexibility as it tries to find low-energy conformations. More than twenty fast relax trajectories are run for each dimer for each sequence and the lowest energy conformation for each dimer is identified. On the basis of the relax simulations, thirty two design pairs (i.e., Aa/Bb pairs) are chosen for an initial round of experimental characterization (Table 1).
Additionally, through visual inspection of the interface, pairs of residues are identified where electrostatic (charge-charge) repulsion mutations could be inserted across the mis-paired interface. Sets of charge mutations were made at these positions and run through Rosetta's fast-relax protocol to ensure that these mutations did not destabilize the correctly-paired interactions. Following these simulations, a set of four candidate mutations (Table 2) are selected for further experimental characterization.
After experimental validation of the initial designs using 2D UPLC (as described in the methods of Example 2, below), combinations of mutations from Design families 1 and 2 (Table 1) are also relaxed to identify designs that appear to destabilize both mis-paired interactions. Nine designs, (depicted in Table 3) are selected for experimental characterization.
A. Cloning of Wild-Type CH1-Fc/Cκ Constructs and Incorporation of Designs for Specificity and Stability Screening.
To interrogate the ability of select CH1/Cκ designs (i.e., as described in Example 1) to provide a specific interface that discriminates from wild-type (WT) or alternately designed CH1/Cκ interfaces, it is useful to remove the variable domains to observe CH1/Cκ-specific pairing strengths as previous work in the field showed that the variable domain interface also influences HC/LC pairing specificity. (Lewis et al., 2014 Nature Biotechnol. 32: 191-198) Additionally, two Cκ constructs are constructed (with or without an N-terminal 8×Histag) to enable charge-based separation of different Cκ proteins on a reverse phase HPLC column using the screening methodology described below. The mutations added to the CH1-Fc/Cκ constructs are designed to enable improved specific assembly of “Aa” and “Bb” HC/LC pairs, relative to the mis-paired “Ab” and “Ba” HC/LC pairs, where ‘A’ is a first CH1-Fc, ‘B’ is a second CH1-Fc, ‘a’ is a first LC Cκ construct designed to pair more specifically with ‘A’ relative to ‘B’, and ‘b’ is a second LC Cκ construct designed to pair more specifically with ‘B’ relative to ‘A’ (see Tables 1-3).
Thus, human IgG1 HC and kappa LC constructs lacking variable domain genes are constructed in pEHG1 and pEHK vectors (Lonza), modified in-house for general antibody HC and LC expression. The Wild-Type (no designs) pEHG1_CH1-Fc plasmid is generated by direct recombinase cloning of two separate and overlapping GeneBlocks (“gBlocks”, Integrated DNA Technologies (IDT)) coding for the CH1/hinge region and the CH2-CH3, respectively, into the pEHG1 vector using HindIII and EcoRI restriction sites. The hinge-encoding region also contains a factor Xa cleavage site to allow isolation of the CH1/Cκ heterodimer from the IgG1-Fc region for crystallography applications. (see SEQ ID NO:1) The Wild-Type (no designs) pEHK_Cκ (SEQ ID NO:2) and pEHK_8×HIS_Cκ (SEQ ID NO:3) plasmids are created by recombinase cloning of single gBlocks (IDT) into the pEHK vector using AgeI and EcoRI restriction sites.
The computational and rational design modifications are introduced into the pEHG1_CH1-Fc, pEHK_Cκ, and pEHK_8×HIS_Cκ plasmids in one of two ways. The first procedure employs site directed primer based mutagenesis. Briefly, the site-directed mutagenesis protocol employs a supercoiled double-stranded DNA vector and two synthetic oligonucleotide primers (IDT) containing the desired mutation(s). The oligonucleotide primers, each complementary to opposite strands of the vector, are extended during thermal cycling by DNA polymerase (HotStar HiFidelity Kit, Qiagen Cat. #202602) to generate an entirely new mutated plasmid. Following temperature cycling, the product is treated with Dpn I enzyme (New England BioLabs, Cat #R0176). The Dpn I enzyme cleaves only methylated parental DNA derived from the parental plasmid which is prepared in E. coli. Each newly generated mutant plasmid pool is then transformed into E. coli strain TOP 10 competent cells (Life Technologies). The second method employs synthesized dual or single gBlocks (IDT) containing 15 base pair 5′ and 3′ overlaps to allow recombinase-based cloning into pEHG1_CH1-Fc plasmids using restriction sites AgeI and BamHI or cloning into pEHK_Cκ and/or pEHK_8×HIS_Cκ plasmids digested with AgeI and EcoRI. The recombinase-based cloning is performed using the In-Fusion protocol (Clontech Laboratories, Inc.) to generate the clone. The In-Fusion construct is then transformed into E. coli strain TOP 10 competent cells (Life Technologies). Colonies are picked and clonal DNA is produced by miniprepping according to standard procedures (Qiagen MiniPrep), and sequenced in-house. Medium and large scale plasmid purifications are performed according to the instructions within the Plasmid Plus Midiprep Kit (Qiagen Cat. #12965) and Maxiprep Plus Kit (Qiagen Cat. #12965), respectively.
B. Protein Expression in Human Embryonic Kidney Cells (HEK293) or Chinese Hamster Ovary (CHO) Cells.
To test designs for their ability to enable specific assembly of select CH1/Cκ complexes, for each design an ‘A’ or ‘B’ CH1-Fc construct (containing the CH1 design sequence) is co-transfected with both ‘a’ and ‘b’ Cκ constructs (containing the Cκ design sequences) for mammalian cell expression and soluble protein secretion. Thus, for each design, the ‘A’ or ‘B’ CH1-Fc HC protein is exposed to both LC Cκ proteins. Expressed protein is purified from the mammalian cell culture supernatants, reduced, and characterized by gradient reverse phase (RP) HPLC in a two-dimensional chromatography process (described below) to determine whether the designs induce a preference in pairing of the CH1-Fc proteins with one Cκ protein over the other.
Briefly, constructs are expressed transiently either in HEK293 or CHO cells according to protocols previously described in the literature (Lewis, et al. (2014), Nat. Biotechnol., 32; 191-198 and Rajendra et al. (2015), Biotechnology and Bioengineering, 112; 977-986). To screen select designs as described in Example 1, for each design, (i) pEHG1_CH1-Fc (containing ‘A’ or ‘B’ side CH1 design sequence), (ii) pEHK Cκ 8×HIS, and (iii) pEHK Cκ plasmids (all lacking variable domain genes, e.g., “VL Minus”) are all transfected transiently into HEK293F or CHO cells using a 1:1.5:1.5 plasmid ratio, respectively. The “a” side Cκ design sequences (see Tables 1-3) are typically cloned into the pEHK Cκ VL Minus plasmid, while the “b” side Cκ design sequences are typically cloned into the pEHK Cκ 8×HIS VL Minus plasmid. Additionally, for each design screened, each pEHG1_CH1-Fc plasmid (containing either an ‘A’ or ‘B’ side CH1 design sequence) is also co-transfected with only its design counterpart pEHK Cκ VL Minus or pEHK Cκ 8×HIS VL Minus plasmid (using a 1:3 HC/LC ratio) as a control to allow identification of which peak in the reverse phase elution profile (described below) belongs to the Cκ protein versus the 8×His_Cκ protein. Transfected cells are grown at 37° C. in a 5% CO2 incubator while shaking at 125 rpm for 5 days. Secreted protein is harvested by centrifugation at 2K rpm for 5 min. and recovery of the supernatant.
C. Specificity (Correct Assembly) Screening
The specificity or percent correct assembly of the design pairs may be determined using a two-dimension UPLC (2D UPLC) purification/characterization method (tandem protein G+reverse phase-high pressure liquid chromatography (HPLC) with in-vial reduction) or by liquid chromatography/mass spectrometry (LCMS).
2D UPLC is performed using a Dionex Ultimate 3000 Dual Rapid Separation Liquid Chromatography system. Briefly, the first dimension protein G step purifies the expressed CH1-Fc/Cκ protein dimer using a protein G column (POROS® G 20 μm Column, 2.1×30 mm, 0.1 mL part #2-1002-00) equilibrated with 1×PBS prior to sample load. All flow rates are 1 mL/min except the final post elution column wash at 2 mL/min. 450 μL samples of filtered cell culture supernatant is injected onto the protein G column. After washing with 1×PBS, the column is eluted with 100 mM sodium phosphate, pH 2.2 (2 minutes). Protein G eluents are collected into vials pre-filled with 20 μL 1M TCEP (tris(2-carboxyethyl)phosphine) in an auto sampler held at ambient temperature. Titers of expressed CH1-Fc/Cκ protein dimer are determined by comparison to eluent peak areas obtained from a standard curve of an in-house human IgG protein G purification.
The second dimension is for characterization of the relative ratio of each Cκ protein (“a” side designs in Cκ OR “b” side designs in 8×HIS_Cκ, see Tables 1-3) that binds to each CH1-Fc protein. The method utilizes two buffers: Buffer A being 100% H2O and 0.05% trifluoroacetic acid (TFA); Buffer B being 100% acetonitrile (CAN), 0.05% TFA. All flow rates are 1 mL/min. The method injects each purified and reduced sample onto a Waters Symmetry C18 column, 4.6×75 mm, 3.5 μm (WAT066224) equilibrated in 95% Buffer A/5% Buffer B. Once each sample is captured onto the column, a gradient is applied starting at 10% ACN and linearly going to 40% ACN in 13 minutes. The column is then flushed with up to 70% ACN for 2 minutes and re-equilibrated with 5% ACN for 2 minutes prior to the next injection. The reversed-phase profile typically includes three peaks; one for each of the Cκ and Cκ 8×HIS polypeptides, and one for the CH1-Fc polypeptide. Comparisons by reversed-phase chromatography are made by overlaying the control samples (as described in Step B above) with test samples. The areas under each peak are determined to calculate percent correct assembly of the particular CH1/Cκ design pair.
Alternatively, test articles may be analyzed for specific assembly by LCMS. Briefly, test articles may be purified from supernatants using the UPLC method as described above. However, instead of reducing the samples in TCEP and running the 2nd dimension reverse phase column, the samples are submitted for LCMS characterization as generally described previously (See Lewis, et al. (2014), Nat. Biotechnol., 32; 191-198).
D. Thermal Stability Determinations
Enzyme-linked immunosorbent assays (ELISAs) or differential-scanning calorimetry (DSC) assays for the detection of thermo-challenged protein samples may be performed to compare the stability of the designed samples against the Wild-Type control proteins. For ELISAs, briefly, 96-well U-bottom high protein binding 96-well plates (Greiner bio-one, cat #650061) are coated overnight at 4° C. with 100 μL/well with 1 μg/ml of Sheep anti human IgG (Fd) (Meridian Life Science Cat. #W90075C-1) in a 0.05 M NaHCO3 buffer, pH 8.3. The plates are then washed four times with PBS with 0.1% TWEEN® (PBST) and blocked for 1 hour with casein (Thermo Scientific, cat #37528) at 37° C. The plates are washed again and 100 μL/well of culture supernatants containing the “variable minus” CH1-Fc proteins expressed with their cognate “variable minus” Cκ proteins (normalized to be at about 100 ng/ml) are incubated for 1 hr. at 37° C. The supernatants are pre-exposed to various temperatures for 1 hr using a Thermal cycler with a 25° C. thermal gradient window (55° C. to 80° C.). The plates are then washed and Goat-anti-human Kappa-HRP (Southern Biotech Cat. #2060-05) at 1:8000 in casein is added and incubated for 1 hr at room temperature. The plates are then washed and 1 step Ultra TMB ELISA substrate (Thermo Scientific Cat. #34208) is added at 50 μL/well. The reaction is allowed to proceed for 1-15 minutes then quenched by the addition of (50 μL) 2.5M H2SO4. The absorbance at 450 nm is then read using a SPECTRAMAX® 190 UV plate reader (Molecular Devices).
Alternatively, the stability of purified proteins (i.e., WT and design constructs lacking variable domains purified, for example, by FPLC using Protein A) may be characterized using differential scanning calorimetry (DSC), essentially as follows. The midpoints of the thermal unfolding transitions (denoted ‘Tm’) of the CH1/Cκ domains provide a measure of their relative stability. DSC is performed using an automated capillary DSC system (capDSC, GE Healthcare). Protein solutions and reference (buffer) solutions are sampled automatically from a 96-well plate using the robotic attachment. Before each protein scan, at least one buffer/buffer scan is performed to define the baseline for subtraction. All 96-well plates containing protein are stored within the instrument at 6° C. Samples are run at 1.0 mg/ml protein concentration in PBS. Scans are performed from 10 to 110° C. at 90° C./hr using the low feedback mode. Scans are analyzed using the Origin software supplied by the manufacturer. Subsequent to the subtraction of reference baseline scans, nonzero protein scan baselines are corrected using a third-order polynomial.
E. Specificity of Assembly and Thermal Stability Characterization Results
Select initial and combination designs in the Cκ/CH1-Fc constructs lacking variable domains are evaluated for specificity of correct assembly as determined by reverse phase HPLC and/or LCMS according to procedures as described above. Results of specific assembly characterizations are provided in the Table 4 below.
The Wild-Type (WT) ‘b’ Cκ with the 8×Histag expresses slightly poorer than the WT ‘a’ Cκ without the tag resulting in a roughly 75/25 ratio in the absence of any designs (Table 4). Many of the initial designs show modest increases in “Aa” and/or “Bb” assembly but are not considered further due to decreases in expression, likely due to destabilization of the interface. However, certain designs express well and improve the percent of “Aa” and/or “Bb” assembly. These include designs 1.3, 1.18, 2.3, and 12.1. A second round of designs combining the best mutations from the initial screen are generated in the same Cκ/CH1-Fc constructs. Combining certain designs results in modest increases in specificity of assembly over the initial designs. Many combination designs again result in reduced protein expression and are not considered further. Certain designs, however, result in near complete specificity of pairing with ‘A’ CH1-Fc assembling with near complete specificity to ‘a’ Cκ, and ‘B’ CH1-Fc assembling with near complete specificity to ‘b’ Cκ. These designs include 14.1.2, 14.3.1.1, 14.3.1.2, 15.1, and 15.2 (Table 4). To provide a secondary method for quantitating the assembly of the Cκ/CH1-Fc proteins, a subset of the designs (14.1.2, 14.3.1.1, and 14.3.1.2) are submitted for LCMS analyses. Based on the mass spectrometry results, each of these designs show near complete specificity of assembly of “Aa” and “Bb” relative to the mis-paired “Ab” and “Ba” species, similar to the data produced using the reverse phase HPLC method (Table 4).
Species of select combination designs in the Cκ/CH1-Fc constructs lacking variable domains (i.e. “Aa” or “Bb” dimers) are evaluated for thermal stability using DSC according to procedures essentially as described above. Results of thermal stability characterizations are provided in the Table 5 below.
The 14.1.2, 14.3.1.1, 15.1, and 15.2 design constructs do not result in reduced stability compared to the wild-type CH1/Cκ domains (Table 5). CH1/Cκ domains containing either CH1_S188A/Cκ_S176I or CH1_S188I/Cκ_S176A are found to be stabilized over WT CH1/Cκ based on their midpoints of thermal denaturation (Tm) measured using DSC. 14.3.1.1 and 15.1 both contain CH1_S188A/Cκ_S176I and are significantly more stable than the WT CH1/Cκ heterodimer (Table 5). In summary, the data in Table 5 demonstrates that the indicated designs, which each enable specific CH1/Cκ assembly, are essentially as stable, or more stable than the WT heterodimer.
Example 3: Bispecific AntibodiesA. Cloning of IgG BsAbs Harboring Novel CH1/Cκ Designs
Human IgG1 bispecific antibodies containing select CH1/Cκ design mutations or WT CH1/Cκ are constructed using pEHG1 (HC) and pEHK (LC) vectors, as generally described above. Variable domains from parental mAbs Pertuzumab (Franklin, M. C. et al. (2004), Cancer Cell; 5; 317-328), MetMAb (Merchant, M., et al. (2013), Proc. Nat'l. Acad. Sci. USA; 110; E2987-E2996), Matuzumab (Schmiedel, J., et al. (2008), Cancer Cell; 13; 365-373) and BHA10 (Jordan, J. L., et al. (2009), Proteins; 77; 832-841) are used in preparation of test articles (fully IgG bispecific antibodies). The Pertuzumab and MetMAb parental mAb constructs are chosen as the receptacles for the HC_“A” and LC_“a” design sequences for each of the CH1/Cκ designs tested, while the BHA10 and Matuzumab parental mAb constructs are chosen as the receptacles for the HC_“B” and LC_“b” design sequence for each of the CH1/Cκ designs tested. Design mutations are introduced using either the site-directed mutagenesis or gBlock recombinase cloning methods, also as described above. Each bispecific antibody is further engineered to contain select CH3 domain design mutations (e.g., Design 7.8.60 as described in Leaver-Fay A., et al. (2016), Structure; 24; 641-651 and WO 2016/118742 (A1)) to improve HC heterodimerization, as well as an N297Q mutation in each HC to reduce N-linked glycosylation. Additionally, select variable domain design mutations (e.g. Designs “AB” or “H4DR”, each as described in WO2014/150973) are each separately and individually introduced into one of the VH VL interfaces of each bispecific antibody to evaluate the impact of specificity designs in both the variable and constant domains of the Fabs. Plasmid isolation, sequencing and scale-up are essentially as described above for constructs lacking variable domains
B. Protein Expression
For IgG bispecific antibody production, four plasmids (two that contain one of the two HC encoding sequences (i.e., HC_“A” or HC_“B”) and two that contain one of the two LC encoding sequences (i.e., LC_“a” and LC_“b”)) are co-transfected in HEK293F cells (using 1:3 HC:LC plasmid ratios) or CHO cells (using 1:1 HC:LC plasmid ratios). Transfected cells are grown at 37° C. in an 8% CO2 incubator while shaking at 125 rpm for 5 days (HEK293F cells) or 6 days (CHO cells). For both HEK293 and CHO, secreted protein material is harvested by centrifugation at 5 K rpm for 5 min at the end of the culture period. Supernatants are passed through 0.22 m filters (small scale) for either large or small scale purification.
Table 6 below provides the parental mAb components and Sequence Identification Numbers (SEQ ID NOs.) of the complete HCs and LCs of the fully IgG bispecific antibodies constructed with, and without, select CH1/Cκ designs as described herein.
C. Specificity (Correct Assembly) Screening of Fully IgG Bispecific Antibodies
The IgG BsAb HC and LC constructs are generated and expressed as described above. Secreted supernatants are purified using the HPLC protein G method as described above for purifying the Cκ/CH1-Fc proteins, however, the purified proteins are not reduced and submitted for reverse phase chromatography but rather are collected and submitted for LCMS analysis essentially as described in Lewis et al., 2014 Nature Biotechnol; 32; 191-198. Table 7 below provides the percent assembly of the correctly paired BsAb as well and the mis-paired species containing two LC_“a” or two LC_“b” light chains as well as those containing HC_“A”/HC_“A” and HC_“B”/HC_“B” homodimers. All values in the table represent the mean and standard deviation of at least three separate experiments.
The data in Table 7 indicates that all of the indicated designs resulted in >80% correctly paired BsAb assembly for each of the constructs prepared. Further, for the Pertuzumab component-containing constructs, all of the tested CH1/Cκ designs displayed large and significant increases in percent correct assembly of BsAb compared to their WT CH1/Cκ domain counterparts. (Table 7).
D. Bispecific Antibody Binding Activity Assay
The dual-binding activity of the same synthesized IgG BsAbs is assessed using a sandwich ELISA. Two Sandwich ELISAs are developed for detecting the four different BsAb test articles; one for detecting anti-HER-2/anti-EGFR BsAb activity, one for detecting anti-HER-2/anti-LTPR BsAb activity, one for detecting anti-cMET/anti-EGFR BsAb activity and one for detecting anti-cMET/anti-LTPR BsAb activity. For all ELISAs, clear 96-well round bottom high binding Immulon microtiter plates (Greiner bio-one, cat #650061) are coated overnight at 2-8° C. with 50 μL/well 1 μg/mL hHER-2-Fc or 1 μg/mL hHGFR(cMet)-Fc (both from R&D systems) in a 50 mM Na2CO3 pH 8.3 buffer. The plates are washed 4 times with PBST and blocked with 200 μL/well casein buffer (Pierce) for 1 hr at room temperature. The plates are then washed 4 times with PBST and the parental IgG controls or BsAb IgG test articles are added at 50 μL/well and μg/mL and serially diluted 1:3 down the plate. The controls and test articles are incubated on the plate for 1 hr at room temperature. The plates are then washed 4 times with PBST and 50 μL/well 1 μg/mL hEGFR-Fc-biotin or hLTβR-Fc-biotin (both from R&D systems) is added for 1 hr at room temperature. The plates are then washed 4 times with PBST followed by the addition of a 50 μL/well streptavidin-AP (Jackson Immunoresearch Labs Cat. #016-050-084) diluted 1:1000 in casein buffer. The streptavidin-AP is incubated in each well for 1 hr at room temperature. The plates are then washed 4 times with PBST and 100 μL/well 1-step PNPP substrate is added (Thermo Scientific Cat. #37621). After approximately 5-15 minutes, plates are read for Absorbance (405 nm) using a SPECTRAMAX® UV plate reader (Molecular Devices). Biotin-labeling of the hEGFR-Fc and hLTβR-Fc proteins is performed using EZ-LINK™ Sulfo-NHS-LC-Biotin (Thermo Scientific Cat. #21327) according to the manufacturer's protocol. The BsAb titrations are fit to yield EC50 values that are listed in Table 8 below.
All of the IgG BsAbs proteins showed strong bispecific binding activity towards their target antigens, but not towards the mis-matched antigen sandwich pairs. Some of the EC50s for the BsAbs are lower than what is observed for others (Table 8). This seems to track closely with the level of half-antibody (non-covalently bound single HC/LC species) generation that occurs when one HC/LC pair expresses at a higher level than the other HC/LC pair in solution.
E. Fully IgG Bispecific Antibodies without Variable Domain Designs.
To assess the impact of the CH1/Cκ designs to improve IgG BsAb assembly in the absence of variable domain designs (e.g., Design “AB” and “H4DR” as described in WO2014/150973 A1), fully IgG BsAbs are constructed incorporating a subset of the CH1/Cκ designs described herein (i.e., Designs 14.1.2, 14.3.1.1, and 14.3.1.2). In addition to the CH1/Cκ designs, each of the constructs also contains CH3 domain design mutations to improve HC heterodimerization (i.e., Design 7.8.60 as described in Leaver-Fay et al (2016) and WO 2016/118742 A1), as well as an N297Q mutation in each HC to reduce N-linked glycosylation. Cloning, expression, and purification of the test articles is performed essentially as described above. Also as described above, the Pertuzumab and MetMAb parental mAb constructs are chosen as the receptacles for the HC_“A” and LC_“a” design sequences for each of the CH1/Cκ designs tested, while the BHA10 and Matuzumab parental mAb constructs are chosen as the receptacles for the HC_“B” and LC_“b” design sequence for each of the CH1/Cκ designs tested.
Table 9 below provides the parental mAb components and Sequence Identification Numbers (SEQ ID NOs.) of the complete HCs and LCs of the fully IgG bispecific antibodies constructed with, and without, select CH1/Cκ designs as described herein (but without any variable domain designs).
The fully IgG BsAbs containing the CH1/Cκ Designs 14.1.2, 14.3.1.1, and 14.3.1.2 and the CH3 Design 7.8.60 (but lacking variable domain designs) are similarly characterized for specificity of assembly using LCMS as described above and in Lewis et al., 2014 Nature Biotechnol. 32: 191-198. Table 10 below provides the percent assembly of the correctly paired BsAb as well and the mis-paired species containing two LC_“a” or two LC_“b” light chains as well as those containing HC_“A”/HC_“A” and HC_“B”/HC_“B” homodimers. All values in the table represent the mean and standard deviation of at least three separate experiments.
The data in Table 10 indicates that the CH1/Cκ domains generally improve correct HC/LC pairing within fully IgG BsAb even in the absence of variable domain designs in the Fab regions. In the majority of cases, incorporating the CH1/Cκ designs alone in the Fab improves correct HC/LC pairing, though some increases are small and the percent correct assembly levels for the full IgG BsAb do not generally achieve the levels observed when the variable domain designs are also included in the Fab regions.
Sequences
Claims
1. A first and second fragment, antigen binding (Fab) comprising:
- a first heavy chain variable domain (VH), a first human IgG heavy chain constant (CH1) domain having an alanine at residue 145 according to Kabat Numbering and an alanine or a glycine at residue 188 according to Kabat Numbering, a first light chain variable (VL) domain, and a first human light chain kappa constant (Ck) domain having an arginine at residue 131 according to Kabat Numbering and an isoleucine at residue 176 according to Kabat Numbering; and
- a second heavy chain variable (VH) domain, a second human constant CH1 domain, a second light chain variable (VL) domain, and a second human light chain kappa (Ck) domain, wherein
- each of the first VH domain and the first VL domain comprise three complementarity determining regions (CDRs) which direct binding to a first antigen,
- each of the second VH domain and the second VL domain comprise three CDRs which direct binding to a second antigen that differs from the first antigen, and
- (i) the second human CH1 domain has the wild-type human IgG CH1 sequence and the second human Ck domain has the wild type human Ck sequence,
- (ii) the second human CH1 domain comprises an isoleucine at residue 188 according to Kabat Numbering and the second human Ck domain has an alanine or a glycine at residue 176 according to Kabat Numbering, or
- (iii) the second human CH1 domain comprises a glutamic acid at residue 221 according to Kabat Numbering and the second human Ck domain has lysine at residue 123 according to Kabat Numbering.
2. The first and second fragment, antigen binding (Fab) according to claim 1, wherein the first human CH1 domain further comprises a glutamic acid at residue 221 according to Kabat Numbering and the human Ck domain further comprises a lysine at residue 123 according to Kabat Numbering and wherein the second human CH1 domain has the wild-type human IgG CH1 sequence and the second human Ck domain has the wild-type human Ck sequence.
3. The first and second fragment, antigen binding (Fab) according to claim 1, wherein
- (a) the first VH domain comprises a glutamic acid at residue 62 and a lysine at residue 39 according to Kabat Numbering,
- (b) the first VL domain is kappa isotype and comprises an arginine at residue 1 and an aspartic acid at residue 38 according to Kabat Numbering,
- (c) the second VH domain comprises a tyrosine at residue 39 and an arginine at residue 105 according to Kabat Numbering, and
- (d) the second VL domain is kappa isotype and comprises an arginine at residue 38 and an aspartic acid at residue 42 according to Kabat Numbering.
4. The first and second fragment, antigen binding (Fab) according to claim 1, wherein
- (a) the first VH domain comprises a tyrosine at residue 39 and an arginine at residue 105 according to Kabat Numbering,
- (b) the first VL domain is kappa isotype and comprises an arginine at residue 38 and an aspartic acid at residue 42 according to Kabat Numbering,
- (c) the second VH domain comprises a glutamic acid at residue 62 and a lysine at residue 39 according to Kabat Numbering, and
- (d) the second VL domain is kappa isotype and comprises an arginine at residue 1 and an aspartic acid at residue 38 according to Kabat Numbering.
5. The first and second fragment, antigen binding (Fab) according to claim 1, wherein each of the first and second human CH1 domains are individually IgG1 or IgG4 isotype.
6. The first and second fragment, antigen binding (Fab) according to claim 5, wherein each of the first and second human CH1 domains are IgG1 isotype.
7. The first and second fragment, antigen binding (Fab) according to claim 5, wherein each of the first and second human CH1 domains are IgG4 isotype.
8. An IgG bispecific antibody comprising:
- a first Fab comprising a first VH domain, a first human IgG constant region comprising a first human CH1 domain having an alanine at residue 145 according to Kabat Numbering and an alanine or a glycine at residue 188 according to Kabat Numbering, a first VL domain, and a first human Ck domain comprising an arginine at residue 131 according to Kabat Numbering and an isoleucine at residue 176 according to Kabat Numbering; and
- a second Fab comprising a second VH domain, a second human VL domain, and a human IgG constant region comprising a second human CH1 domain and a second human Ck domain, wherein
- each of the first VH domain and the first VL domain comprise three CDRs which direct binding to a first antigen,
- each of the second heavy chain and light chain variable domains comprise three CDRs which direct binding to a second antigen that differs from the first antigen, and
- (i) the second human CH1 domain having a wild-type human IgG CH1 sequence and the second human Ck domain having a wild type human Ck sequence,
- (ii) the second human CH1 domain comprises an isoleucine at residue 188 according to Kabat Numbering and the second human Ck domain has an alanine or a glycine at residue 176 according to Kabat Numbering, or
- (iii) the second human IgG heavy chain constant region comprises a second human CH1 domain that comprises a glutamic acid at residue 221 according to Kabat Numbering and the second human Ck domain has lysine at residue 123 according to Kabat Numbering.
9. The IgG bispecific antibody according to claim 8, wherein the first human CH1 domain further comprises glutamic acid at residue 221 according to Kabat Numbering and the first human Ck domain further comprises a lysine at residue 123 according to Kabat Numbering, wherein the second human CH1 domain has the wild-type human IgG CH1 sequence and the second human Ck domain has the wild-type human Ck sequence.
10. The IgG bispecific antibody according to claim 8, wherein
- (a) the first VH domain comprises a glutamic acid at residue 62 and a lysine at residue 39 according to Kabat Numbering,
- (b) the first VL domain is kappa isotype and comprises an arginine at residue 1 and an aspartic acid at residue 38 according to Kabat Numbering,
- (c) the second VH domain comprises a tyrosine at residue 39 and an arginine at residue 105 according to Kabat Numbering, and
- (d) the second VL domain is kappa isotype and comprises an arginine at residue 38 and an aspartic acid at residue 42 according to Kabat Numbering.
11. The IgG bispecific antibody according to claim 8, wherein
- (a) the first VH domain comprises a tyrosine at residue 39 and an arginine at residue 105 according to Kabat Numbering,
- (b) the first VL domain is kappa isotype and comprises an arginine at residue 38 and an aspartic acid at residue 42 according to Kabat Numbering;
- (c) the second VH domain comprises a glutamic acid at residue 62 and a lysine at residue 39 according to Kabat Numbering, and
- (d) the second VL domain is kappa isotype and comprises an arginine at residue 1 and an aspartic acid at residue 38 according to Kabat Numbering.
12. The IgG bispecific antibody according to claim 8, wherein one of the first or second human IgG constant regions comprises a CH3 domain comprising an alanine at residue 407 according to EU Index Numbering; and the other of the first or second human IgG constant regions comprises a CH3 domain comprising a valine or methionine at residue 366 and a valine at residue 409 according to EU Index Numbering.
13. The IgG bispecific antibody according to claim 8, wherein one of the first or second human IgG constant regions comprises a CH3 domain having an alanine at residue 407, a methionine at residue 399, and an aspartic acid at residue 360 according to EU Index Numbering; and the other of the first or second human IgG constant regions comprising a CH3 domain having a valine at residue 366, a valine at residue 409, and an arginine at residues 345 and 347 according to EU Index Numbering.
14. The IgG bispecific antibody according to claim 8, wherein one of the first or second human IgG constant regions comprises a CH3 domain having an alanine at residue 407, a glycine at residue 356, an aspartic acid at residue 357, and a glutamine at residue 364 according to EU Index Numbering; and the other of the first or second human IgG constant regions comprises a CH3 domain having a methionine at residue 366, a valine at residue 409, a serine at residue 349, and a tyrosine at residue 370 according to EU Index Numbering.
15. The IgG bispecific antibody according to claim 8, wherein each of the first and second human CH1 domains are IgG1 or IgG4 isotype.
16. The IgG bispecific antibody according to claim 15, wherein each of the first human CH1 domain and the second human CH1 domain are IgG1 isotype.
17. The IgG bispecific antibody according to claim 15, wherein each of the first human CH1 domain and the second human CH1 domain are IgG4 isotype.
18. The IgG bispecific antibody according to claim 8, wherein each of the first VL domain and the second VL domain is human kappa isotype.
19. A first and second fragment, antigen binding (Fab) comprising: wherein
- (a) a first heavy chain variable domain (VH) and a first human IgG heavy chain constant CH1 (CH1) domain having an alanine at residue 145 according to Kabat Numbering and a glutamic acid at residue 221 according to Kabat Numbering;
- (b) a first light chain variable domain (VL) and a first human light chain kappa constant (Ck) domain having an arginine at residue 131 according to Kabat Numbering and a lysine at residue 123 according to Kabat Numbering;
- (c) a second heavy chain variable domain VH and a second human IgG heavy chain constant CH1 domain having a wild-type human IgG CH1 sequence; and
- (d) a second light chain variable VL domain and a second human light chain kappa constant Ck domain having a wild type human Ck sequence,
- each of the first VH domain and the VL domain comprise three complementarity determining regions (CDRs) which direct binding to a first antigen, and
- each of the second VH and VL domains comprise three CDRs which direct binding to a second antigen that differs from the first antigen.
20. The first and second fragment, antigen binding (Fab) of claim 19, wherein,
- (a) the first VH domain comprises a glutamic acid at residue 62 and a lysine at residue 39 according to Kabat Numbering,
- (b) the first VL domain is kappa isotype and comprises an arginine at residue 1 and an aspartic acid at residue 38 according to Kabat Numbering,
- (c) the second VH domain comprises a tyrosine at residue 39 and an arginine at residue 105 according to Kabat Numbering, and
- (d) the second VL domain is kappa isotype and comprises an arginine at residue 38 and an aspartic acid at residue 42 according to Kabat Numbering.
21. The first and second fragment, antigen binding (Fab) according to claim 19, wherein
- (a) the first VH domain comprises a tyrosine at residue 39 and an arginine at residue 105 according to Kabat Numbering,
- (b) the first VL domain is kappa isotype and comprises an arginine at residue 38 and an aspartic acid at residue 42 according to Kabat Numbering,
- (c) the second VH domain comprises a glutamic acid at residue 62 and a lysine at residue 39 according to Kabat Numbering, and
- (d) the second VL domain is kappa isotype and comprises an arginine at residue 1 and an aspartic acid at residue 38 according to Kabat Numbering.
22. The first and second fragment, antigen binding (Fab) according to claim 19, wherein each of the first human CH1 domain and the second human CH1 domain are individually IgG1 or IgG4 isotype.
23. The first and second fragment, antigen binding (Fab) of claim 22, wherein each of the first human CH1 domain and the second human CH1 domain are IgG1 isotype.
24. The first and second fragment, antigen binding (Fab) of claim 22, wherein each of the first human CH1 domain and the second human CH1 domain are IgG4 isotype.
25. A bispecific antibody comprising:
- a first Fab comprising a first VH domain, a first VL domain, a first human IgG constant region comprising a first human CH1 domain having an alanine at residue 145 according to Kabat Numbering and an alanine and a glutamic acid at residue 221 according to Kabat Numbering, and a first human Ck domain comprising an arginine at residue 131 according to Kabat Numbering and a lysine at residue 123 according to Kabat Numbering; and
- a second Fab comprising a second VH domain, a second VL domain, and a human IgG constant region comprising a second human CH1 domain having a wild-type human IgG CH1 sequence and a second human Ck domain having a wild type human Ck sequence, wherein
- each of the first VH domain and the first VL domain comprise three CDRs which direct binding to a first antigen, and
- each of the second heavy chain variable domain and the second light chain variable domain comprise three CDRs which direct binding to a second antigen that differs from the first antigen.
26. A bispecific antibody comprising according to claim 25, wherein,
- (a) the first VH domain comprises a glutamic acid at residue 62 and a lysine at residue 39 according to Kabat Numbering,
- (b) the first VL domain is kappa isotype and comprises an arginine at residue 1 and an aspartic acid at residue 38 according to Kabat Numbering,
- (c) the second VH domain comprises a tyrosine at residue 39 and an arginine at residue 105 according to Kabat Numbering, and
- (d) the second VL domain is kappa isotype and comprises an arginine at residue 38 and an aspartic acid at residue 42 according to Kabat Numbering.
27. The bispecific antibody according to claim 25, wherein
- (a) the first VH domain comprises a tyrosine at residue 39 and an arginine at residue 105 according to Kabat Numbering,
- (b) the first VL domain is kappa isotype and comprises an arginine at residue 38 and an aspartic acid at residue 42 according to Kabat Numbering,
- (c) the second VH domain comprises a glutamic acid at residue 62 and a lysine at residue 39 according to Kabat Numbering, and
- (d) the second VL domain is kappa isotype and comprises an arginine at residue 1 and an aspartic acid at residue 38 according to Kabat Numbering.
28. The bispecific antibody according to claim 25, wherein one of the first human IgG constant region or the second human IgG constant region comprises a CH3 domain having an alanine at residue 407 with residue according to EU Index Numbering; and the other of the first human IgG constant region or the second human IgG constant region comprises a CH3 domain having a valine or methionine at residue 366 and a valine at residue 409 according to EU Index Numbering.
29. The bispecific antibody according to claim 25, wherein one of the first human IgG constant region or the second human IgG constant region comprises a CH3 domain having an alanine at residue 407, a methionine at residue 399, and an aspartic acid at residue 360 according to EU Index Numbering; and the other of the first human IgG constant region or the second human IgG constant region comprises a CH3 domain having a valine at residue 366, a valine at residue 409, and an arginine at residues 345 and 347 according to EU Index Numbering.
30. The bispecific antibody according to claim 25, wherein one of the first human IgG constant region or the second human IgG constant region comprises a CH3 domain having an alanine at residue 407, a glycine at residue 356, an aspartic acid at residue 357, and a glutamine at residue 364 according to EU Index Numbering; and the other of the first human IgG constant region or the second human IgG constant region comprises a CH3 domain having a methionine at residue 366, a valine at residue 409, a serine at residue 349, and a tyrosine at residue 370 according to EU Index Numbering.
31. The bispecific antibody according to claim 25, wherein each of the first human CH1 domain and the second human CH1 domain are IgG1 or IgG4 isotype.
32. The bispecific antibody according to claim 31, wherein each of the first human CH1 domain and the second human CH1 domains are IgG1 isotype.
33. The bispecific antibody according to claim 31, wherein each of the first human CH1 domain and the second human CH1 domain are IgG4 isotype.
34. The bispecific antibody according to claim 25, wherein each of the first VL domain and the second VL domain is human kappa isotype.
Type: Application
Filed: Oct 10, 2023
Publication Date: Feb 8, 2024
Inventors: Stephen John Demarest (San Diego, CA), Karen Jean Froning (Escondido, CA), Brian Arthur Kuhlman (Chapel Hill, NC), Andrew Philip Leaver-Fay (Carrboro, NC)
Application Number: 18/484,361
