Polypeptides for binding to cd80

Abstract

The invention relates to antigen binding proteins for binding to CD80, related fragments thereof, and use thereof for the treatment of various conditions such as inflammation and autoimmunity.

Description

Polypeptides for binding to CD80Field of the invention

[0001] The invention relates to antigen binding protein for binding to CD80, related fragments thereof, and use thereof for the treatment of various conditions such as inflammation and autoimmunity.Related application

[0002] This application claims priority from Australian provisional applicationAU 2023903541 , the entire contents of which are hereby incorporated by reference.Background of the invention

[0003] The costimulatory ligand CD80 and the inhibitory ligand PD-L1 interact in c / s on the surface of antigen presenting cells including dendritic cells. In the context of the c / s- CD80:PD-L1 complex, CD80 can still bind the costimulatory receptor CD28 on interacting T cells, but PD-L1 cannot bind the T cell inhibitor receptor PD1. Hence, these complexes activate naive T cells by allowing DC surface CD80 to trigger CD28 signalling without inhibition by PD-L1.

[0004] The APC-expressed co-stimulatory ligands CD80 and CD86 are also ligands for cell surface CTLA4, in addition to CD28.

[0005] Regulatory T cells (Tregs) constitutively express abundant CTLA4, and inhibit co-stimulation by an additional mechanism whereby CD80 and CD86 are depleted from the APC surface through CTLA4-mediated transendocytosis.

[0006] Due to the critical role of the CD80 / CD86 co-stimulatory pathway in promoting and maintaining immune response, therapeutic agents designed to antagonize the pathway are in clinical use for the treatment of autoimmune diseases and disorders. One approach has been the development of Abatacept (Orencia®), a CTLA4-lg fusion protein consisting of the extracellular binding domain of CTLA4 linked to the Fc domain of a human IgG. Abatacept was developed to inhibit CD80-mediated co-stimulation and is approved for the treatment of rheumatoid arthritis (RA) and in clinical trials for a number of other autoimmune indications.

[0007] Another approach has been the development of anti-CD80 antibodies, some of which block the interaction of CD80 with CD28 and others and others which bind to the PD-L1 binding site on CD80. Thus, antibodies for binding to CD80 may have differing mechanisms of action and differing effects on the CD80 co-stimulatory pathway.

[0008] There is a need for improved and / or alternative compositions and methods for modulation of the CD80 co-stimulatory pathway.

[0009] Reference to any prior art in the specification is not an acknowledgment or suggestion that this prior art forms part of the common general knowledge in any jurisdiction or that this prior art could reasonably be expected to be understood, regarded as relevant, and / or combined with other pieces of prior art by a skilled person in the art.Summary of the invention

[0010] The present invention relates to antigen binding proteins for binding to CD80, and in particular, antigen binding proteins which block CD80:CD28 interactions and are therefore useful as immunosuppressive agents.

[0011] The invention provides an antigen binding protein for binding to CD80, the antigen binding protein having an antigen binding domain comprising:FR1 - CDR1 - FR2 - CDR2 - FR3 - CDR3 - FR4, andFR1a - CDR1a - FR2a - CDR2a - FR3a - CDR3a - FR4a, wherein:FR1 , FR2, FR3 and FR4 are each framework regions;CDR1 , CDR2 and CDR3 are each complementarity determining regions;FR1a, FR2a, FR3a and FR4a are each framework regions;CDR1a, CDR2a and CDR3a are each complementarity determining regions; wherein the sequence of any of the framework regions or complementarity determining regions are as described herein, preferably as described in the Tables herein.

[0012] In any embodiment, CDR1 , CDR2 and CDR3 refer to complementarity determining regions from the variable heavy chain of an antibody (a VH), CDR1 a, CDR2a and CDR3a are complementarity determining regions from the variable light chain of an antibody (a VL), or where CDR1 , CDR2 and CDR3 are complementarity determining regions from the VL, CDR1a, CDR2a and CDR3a are complementarity determining regions from VH. In such examples, the CDRs may be referred to as CDRH1 , CDRH2, CDRH3, CDRL1 , CDRL2 and CDRL3 as the case may be.

[0013] Reference herein to a protein or antibody that “binds to” CD80 (or CD28 antigen ligand, or B7-1 antigen) provides literal support for a protein or antibody that “binds specifically to” or “specifically binds to” a CD80.

[0014] In preferred embodiments, the second polypeptide, in the form of an antigen binding protein, and that inhibits the binding of CD28 to CD80 is capable of binding to or specifically binding to residues of the membrane distal IgV domain of human CD80 (corresponding to residues G34 to A140 of human CD80). Optionally, the second antigen binding protein as described herein does not bind to the region or portion of CD80 that is bound by CD28, but upon binding to CD80, prevents or reduces the binding of CD28 to CD80.

[0015] In preferred embodiments, the second antigen binding protein as described herein is capable of binding to or specifically binding to the region or portion of CD80 that is bound by CD28.

[0016] In certain embodiments, upon binding to CD80, the second antigen binding protein does not inhibit the binding of PD-L1 to CD80.

[0017] In any embodiment, the invention provides an antigen binding protein for binding to CD80, wherein the antigen binding protein competitively inhibits the binding to CD80 of an antibody:- comprising a VH comprising a sequence as set forth in SEQ ID NO: 78 and a VL comprising a sequence as set forth in SEQ ID NO: 145;- comprising a VH comprising a sequence as set forth in SEQ ID NO: 79 and a VL comprising a sequence as set forth in SEQ ID NO: 146;- comprising a VH comprising a sequence as set forth in SEQ ID NO: 80 and a VL comprising a sequence as set forth in SEQ ID NO: 147;- comprising a VH comprising a sequence as set forth in SEQ ID NO: 81 and a VL comprising a sequence as set forth in SEQ ID NO: 148;- comprising a VH comprising a sequence as set forth in SEQ ID NO: 82 and a VL comprising a sequence as set forth in SEQ ID NO: 149;- comprising a VH comprising a sequence as set forth in SEQ ID NO: 83 and a VL comprising a sequence as set forth in SEQ ID NO: 150; or- comprising a VH comprising a sequence as set forth in SEQ ID NO: 84 and a VL comprising a sequence as set forth in SEQ ID NO: 151.

[0018] In any embodiment, the invention provides an antigen binding protein with a CDRH1 , a CDRH2 and / or a CDRH3 of an antigen binding domain having a variable heavy chain as defined in any one of SEQ ID NOs: 78 to 84.

[0019] In any embodiment, the invention provides an antigen binding protein with a CDRL1 , a CDRL2 and / or a CDRL3 of an antigen binding domain having a variable light chain as defined in any one of SEQ I D NOs: 145 to 151 .

[0020] In any embodiment, the invention provides an antigen binding protein for binding to CD80, the protein comprising:- a CDR1 , a CDR2 and a CDR3 of an antigen binding domain having a variable heavy chain as defined in SEQ ID NO: 78, and a CDR1 , a CDR2 and a CDR3 of an antigen binding domain having a variable light chain as defined in SEQ ID NO: 145;- a CDR1 , a CDR2 and a CDR3 of an antigen binding domain having a variable heavy chain as defined in SEQ ID NO: 79, and a CDR1 , a CDR2 and a CDR3 of an antigen binding domain having a variable light chain as defined in SEQ ID NO:- a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable heavy chain as defined in SEQ ID NO: 80, and a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable light chain as defined in SEQ ID NO: 147;- a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable heavy chain as defined in SEQ ID NO: 81, and a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable light chain as defined in SEQ ID NO: 148;- a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable heavy chain as defined in SEQ ID NO: 82, and a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable light chain as defined in SEQ ID NO: 149;- a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable heavy chain as defined in SEQ ID NO: 83, and a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable light chain as defined in SEQ ID NO: 150; or- a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable heavy chain as defined in SEQ ID NO: 84, and a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable light chain as defined in SEQ ID NO: 151.

[0021] In any embodiment, an antigen binding protein described herein comprises:FR1 - CDR1 - FR2 - CDR2 - FR3 - CDR3 - FR4 - linker - FR1a - CDR1a - FR2a - CDR2a - FR3a - CDR3a - FR4a.

[0022] As defined herein, the linker may be a chemical, one or more amino acids, or a disulphide bond formed between two cysteine residues.

[0023] In certain preferred embodiments, the invention provides an antigen binding protein comprising, consisting essentially of or consisting of the amino acid sequence of (in order of N to C terminus or C to N terminus) SEQ ID NOs: 78 and 145.

[0024] In certain preferred embodiments, the invention provides an antigen binding protein comprising, consisting essentially of or consisting of the amino acid sequence of (in order of N to C terminus or C to N terminus) SEQ ID NOs: 79 and 146.

[0025] In certain preferred embodiments, the invention provides an antigen binding protein comprising, consisting essentially of or consisting of the amino acid sequence of (in order of N to C terminus or C to N terminus) SEQ ID NOs: 80 and 147.

[0026] In certain preferred embodiments, the invention provides an antigen binding protein comprising, consisting essentially of or consisting of the amino acid sequence of (in order of N to C terminus or C to N terminus) SEQ ID NOs: 81 and 148.

[0027] In certain preferred embodiments, the invention provides an antigen binding protein comprising, consisting essentially of or consisting of the amino acid sequence of (in order of N to C terminus or C to N terminus) SEQ ID NOs: 82 and 149.

[0028] In certain preferred embodiments, the invention provides an antigen binding protein comprising, consisting essentially of or consisting of the amino acid sequence of (in order of N to C terminus or C to N terminus) SEQ ID NOs: 83 and 150.

[0029] In certain preferred embodiments, the invention provides an antigen binding protein comprising, consisting essentially of or consisting of the amino acid sequence of (in order of N to C terminus or C to N terminus) SEQ ID NOs: 84 and 151.

[0030] In a particularly preferred embodiment, the antigen binding protein comprises, consists essentially of or consists of, in order N to C terminus, SEQ ID NO: 145 and SEQ ID NO: 78 (ie VL to VH). Optionally the antigen binding protein comprises SEQ ID NO:145 (VL) - linker - SEQ ID NO: 78 (VH).

[0031] In a particularly preferred embodiment, the antigen binding protein comprises, consists essentially of or consists of, in order N to C terminus, SEQ ID NO: 146 and SEQ ID NO: 79 (ie VL to VH). Optionally the antigen binding protein comprises SEQ ID NO:146 (VL) - linker - SEQ ID NO: 79 (VH).

[0032] In a particularly preferred embodiment, the antigen binding protein comprises, consists essentially of or consists of, in order N to C terminus, SEQ ID NO: 147 and SEQID NO: 80 (ie VL to VH). Optionally the antigen binding protein comprises SEQ ID NO:147 (VL) - linker - SEQ ID NO: 80 (VH).

[0033] In a particularly preferred embodiment, the antigen binding protein comprises, consists essentially of or consists of, in order N to C terminus, SEQ ID NO: 148 and SEQ ID NO: 81 (ie VL to VH). Optionally the antigen binding protein comprises SEQ ID NO:148 (VL) - linker - SEQ ID NO: 81 (VH).

[0034] In a particularly preferred embodiment, the antigen binding protein the antigen binding protein comprises, consists essentially of or consists of, in order N to C terminus, SEQ ID NO: 149 and SEQ ID NO: 82 (ie VL to VH), optionally SEQ ID NO: 149 (VL) - linker - SEQ ID NO: 82 (VH).

[0035] In a particularly preferred embodiment, the antigen binding protein the antigen binding protein comprises, consists essentially of or consists of, in order N to C terminus, SEQ ID NO: 150 and SEQ ID NO: 83 (ie VL to VH), optionally SEQ ID NO: 150 (VL) - linker - SEQ ID NO: 83 (VH).

[0036] In a particularly preferred embodiment, the antigen binding protein the antigen binding protein comprises, consists essentially of or consists of, in order N to C terminus, SEQ ID NO: 151 and SEQ ID NO: 84 (ie VL to VH), optionally SEQ ID NO: 151 (VL) - linker - SEQ ID NO: 84 (VH).

[0037] In any embodiment, the antigen binding domain comprises:(i) a VH comprising a complementarity determining region (CDR) 1 comprising a sequence as set forth in SEQ ID NO: 1 (IMGT) or 13 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; a CDR2 comprising a sequence as set forth in SEQ ID NO: 2 (IMGT) or 14 (Kabat), or a sequence at least 80%, at least 81 %, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; and a CDR3 comprising a sequence as set forth in SEQ ID NO: 3 (IMGT) or 15 (Kabat), or a sequence at least 80%, at least81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(ii) a VH comprising a sequence as set forth in SEQ ID NO: 78, or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(iii) a VL comprising a complementarity determining region (CDR) 1 comprising a sequence as set forth in SEQ ID NO: 85 (IMGT) or 94 (Kabat) or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; a CDR2 comprising a sequence as set forth in SEQ ID NO: 86 (IMGT) or 95 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; and a CDR3 comprising a sequence as set forth in SEQ ID NO: 87 (IMGT) or 96 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(iv) a VL comprising a sequence as set forth in SEQ ID NO: 145, or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(v) a VH comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 1 , a CDR2 comprising a sequence set forth in SEQ ID NO: 2, and a CDR3 comprising asequence set forth in SEQ ID NO: 3; or comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 13, a CDR2 comprising a sequence set forth in SEQ ID NO: 14, and a CDR3 comprising a sequence set forth in SEQ ID NO: 15;(vi) a VL comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 85, a CDR2 comprising a sequence set forth in SEQ ID NO: 86, and a CDR3 comprising a sequence as set forth in SEQ ID NO: 87; or comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 94, a CDR2 comprising a sequence set forth in SEQ ID NO: 95 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 96;(vii) a VH comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 1 , a CDR2 comprising a sequence as set forth in SEQ ID NO: 2, and a CDR3 comprising a sequence as set forth in SEQ ID NO: 3; and a VL comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 85, a CDR2 comprising a sequence as set forth in SEQ ID NO: 86, and a CDR3 comprising a sequence as set forth in SEQ ID NO: 87; or a VH comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 13, a CDR2 comprising a sequence as set forth in SEQ ID NO: 14 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 15; and a VL comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 94, a CDR2 comprising a sequence as set forth in SEQ ID NO: 95 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 96; or(viii) a VH comprising a sequence as set forth in SEQ ID NO: 78, and a VL comprising a sequence set forth in SEQ ID NO: 145.

[0038] When the CDRs are determined according to the IMGT system, the antigen binding domain may further comprise at least one of:(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 28, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 29, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 30, or a sequence at least about 80%, at least 85%, at least 90%, at least91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 31 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 107, or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 108, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 109, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 110, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto.

[0039] When the CDRs are determined according to the Kabat system, the antigen binding domain may further comprise at least one of:(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 51 or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 52, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 53, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 54, or a sequence at least about 80%, at least 85%, at least90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 128, or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 131 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 129, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 110, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto.

[0040] In any embodiment, the antigen binding protein comprises a variable heavy chain comprising the amino acid sequence as set forth in SEQ ID NO: 78, or a sequence at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identical thereto; and a variable light chain comprising the amino acid sequence as set forth in SEQ ID NO: 145; or a sequence at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98 %, or at least about 99% identical thereto; wherein the variable heavy and / or light chains comprise no more than 1 , no more than 2, no more than 3, no more than 4, no more than 5, no more than 6, no more than 7, no more than 8, no more than 9, no more than 10, no more than 11 , no more than 12, no more than 13, no more than 14, no more than 15, no more than 16, no more than 17, no more than 18, no more than 19 or no more than 20 amino acid residue substitutions, deletions, or additions or combination thereof, outside the indicated CDR sequences, and wherein the antigen binding protein retains the ability to bind to CD80.

[0041] In any embodiment, the antigen binding domain comprises:(i) a VH comprising a complementarity determining region (CDR) 1 comprising a sequence as set forth in SEQ ID NO: 1 (IMGT) or 16 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; a CDR2 comprising a sequence as set forth in SEQ ID NO: 2 (IMGT) or 17 or 164(Kabat), or a sequence at least 80%, at least 81 %, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; and a CDR3 comprising a sequence as set forth in SEQ ID NO: 4 (IMGT) or 18 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(ii) a VH comprising a sequence as set forth in SEQ ID NO: 79 or 83, or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(iii) a VL comprising a complementarity determining region (CDR) 1 comprising a sequence as set forth in SEQ ID NO: 85 (IMGT) or 97 (Kabat) or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; a CDR2 comprising a sequence as set forth in SEQ ID NO: 86 (IMGT) or 98 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; and a CDR3 comprising asequence as set forth in SEQ ID NO: 87 (IMGT) or 99 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(iv) a VL comprising a sequence as set forth in SEQ ID NO: 146 or 150, or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(v) a VH comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 1 , a CDR2 comprising a sequence set forth in SEQ ID NO: 2, and a CDR3 comprising a sequence set forth in SEQ ID NO: 4; or comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 16, a CDR2 comprising a sequence set forth in SEQ ID NO: 17 or 164, and a CDR3 comprising a sequence set forth in SEQ ID NO: 18;(vi) a VL comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 85, a CDR2 comprising a sequence set forth in SEQ ID NO: 86, and a CDR3 comprising a sequence as set forth in SEQ ID NO: 87; or comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 97, a CDR2 comprising a sequence set forth in SEQ ID NO: 98 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 99;(vii) a VH comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 1 , a CDR2 comprising a sequence as set forth in SEQ ID NO: 2, and a CDR3 comprising a sequence as set forth in SEQ ID NO: 4; and a VL comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 85, a CDR2 comprising a sequence as set forth in SEQ ID NO: 86, and a CDR3 comprising a sequence as set forth in SEQ ID NO: 87; or a VH comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 16, a CDR2 comprising a sequence as set forth in SEQ ID NO: 17 or 164 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 18; and a VL comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 97, a CDR2 comprising a sequence as set forth in SEQ ID NO: 98 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 99;(viii) a VH comprising a sequence as set forth in SEQ I D NO: 79, and a VL comprising a sequence set forth in SEQ ID NO: 146; or(viv) a VH comprising a sequence as set forth in SEQ ID NO: 83, and a VL comprising a sequence set forth in SEQ ID NO: 150.

[0042] When the CDRs are determined according to the IMGT system, the antigen binding domain may further comprise at least one of:(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 32 or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 29, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 33, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 31 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 111 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 108, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 112, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 110, or a sequence at least about 80%, at least 85%, at least 90%, at least91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto.

[0043] When the CDRs are determined according to the Kabat system, the antigen binding domain may further comprise at least one of:(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 55, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 56 or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 57, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 58, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 130, or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 131 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 132, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 110, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto.

[0044] When the CDRs are determined according to the IMGT system, the antigen binding domain may further comprise at least one of:(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 44, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 45, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 46, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 47, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and(ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 122, or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 123, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 124, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 110, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto.

[0045] When the CDRs are determined according to the Kabat system, the antigen binding domain may further comprise at least one of:(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 71 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 72, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 73, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 74, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 140, or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 141 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 142, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 110, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto.

[0046] In any embodiment, the antigen binding protein comprises a variable heavy chain comprising the amino acid sequence as set forth in SEQ ID NO: 79 or 83, or a sequence at least about 80%, at least about 85%, at least about 90%, at least about 91 %, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identical thereto; and a variable light chain comprising the amino acid sequence as set forth in SEQ ID NO:146 or 150; or a sequence at least about 80%, at least about 85%, at least about 90%, at least about 91 %, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98 %, or at least about 99% identical thereto; wherein the variable heavy and / or light chains comprise no more than 1 , no more than 2, no more than 3, no more than 4, no more than 5, no more than 6, no more than 7, no more than 8, no more than 9, no more than 10, no more than 11 , no more than 12, no more than 13, no more than 14, no more than 15, no more than 16, no more than 17, no more than 18, no more than 19 or no more than 20 amino acid residue substitutions, deletions, or additions or combination thereof, outside the indicated CDR sequences, and wherein the antigen binding protein retains the ability to bind to CD80.

[0047] In any embodiment, the antigen binding domain comprises:(i) a VH comprising a complementarity determining region (CDR) 1 comprising a sequence as set forth in SEQ ID NO: 5 (IMGT) or 19 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; a CDR2 comprising a sequence as set forth in SEQ ID NO: 6 (IMGT) or 20 (Kabat), or a sequence at least 80%, at least 81 %, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; and a CDR3 comprising a sequence as set forth in SEQ ID NO: 7 (IMGT) or 21 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(ii) a VH comprising a sequence as set forth in SEQ ID NO: 80, or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%,at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(iii) a VL comprising a complementarity determining region (CDR) 1 comprising a sequence as set forth in SEQ ID NO: 88 (IMGT) or 100 (Kabat) or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; a CDR2 comprising a sequence as set forth in SEQ ID NO: 89 (IMGT) or 101 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; and a CDR3 comprising a sequence as set forth in SEQ ID NO: 90 (IMGT) or 102 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(iv) a VL comprising a sequence as set forth in SEQ ID NO: 147, or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(v) a VH comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 5, a CDR2 comprising a sequence set forth in SEQ ID NO: 6, and a CDR3 comprising a sequence set forth in SEQ ID NO: 7; or comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 19, a CDR2 comprising a sequence set forth in SEQ ID NO: 20, and a CDR3 comprising a sequence set forth in SEQ ID NO: 21 ;(vi) a VL comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 88, a CDR2 comprising a sequence set forth in SEQ ID NO: 89, and a CDR3 comprising a sequence as set forth in SEQ ID NO: 90; or comprising a CDR1 comprising a sequenceset forth in SEQ ID NO: 100, a CDR2 comprising a sequence set forth in SEQ ID NO: 101 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 102;(vii) a VH comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 5, a CDR2 comprising a sequence as set forth in SEQ ID NO: 6, and a CDR3 comprising a sequence as set forth in SEQ ID NO: 7; and a VL comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 88, a CDR2 comprising a sequence as set forth in SEQ ID NO: 89, and a CDR3 comprising a sequence as set forth in SEQ ID NO: 90; or a VH comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 19, a CDR2 comprising a sequence as set forth in SEQ ID NO: 20 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 21 ; and a VL comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 100, a CDR2 comprising a sequence as set forth in SEQ ID NO: 101 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 102; or(viii) a VH comprising a sequence as set forth in SEQ I D NO: 80, and a VL comprising a sequence set forth in SEQ ID NO: 147.

[0048] When the CDRs are determined according to the IMGT system, the antigen binding domain may further comprise at least one of:(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 34, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 35, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 36, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 31 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; andii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 113, or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 114, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 115, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 116, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto.

[0049] When the CDRs are determined according to the Kabat system, the antigen binding domain may further comprise at least one of:(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 59, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 60, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 61 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 62, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 133, or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or atleast 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 134, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 135, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 136, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto.

[0050] In any embodiment, the antigen binding protein comprises a variable heavy chain comprising the amino acid sequence as set forth in SEQ ID NO: 80, or a sequence at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identical thereto; and a variable light chain comprising the amino acid sequence as set forth in SEQ ID NO: 147; or a sequence at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98 %, or at least about 99% identical thereto; wherein the variable heavy and / or light chains comprise no more than 1 , no more than 2, no more than 3, no more than 4, no more than 5, no more than 6, no more than 7, no more than 8, no more than 9, no more than 10, no more than 11 , no more than 12, no more than 13, no more than 14, no more than 15, no more than 16, no more than 17, no more than 18, no more than 19 or no more than 20 amino acid residue substitutions, deletions, or additions or combination thereof, outside the indicated CDR sequences, and wherein the antigen binding protein retains the ability to bind to CD80.

[0051] In any embodiment, the antigen binding domain comprises:(i) a VH comprising a complementarity determining region (CDR) 1 comprising a sequence as set forth in SEQ ID NO: 163 (IMGT) or 22 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; a CDR2 comprising a sequence as set forth in SEQ ID NO: 8 (IMGT) or 23 (Kabat), or a sequence at least 80%, at least 81 %, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; and a CDR3 comprising a sequence as set forth in SEQ ID NO: 9 (IMGT) or 24 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(ii) a VH comprising a sequence as set forth in SEQ ID NO: 81 , or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(iii) a VL comprising a complementarity determining region (CDR) 1 comprising a sequence as set forth in SEQ ID NO: 88 (IMGT) or 103 (Kabat) or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; a CDR2 comprising a sequence as set forth in SEQ ID NO: 91 (IMGT) or 104 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; and a CDR3 comprising a sequence as set forth in SEQ ID NO: 92 (IMGT) or 105 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(iv) a VL comprising a sequence as set forth in SEQ ID NO: 148, or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(v) a VH comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 163, a CDR2 comprising a sequence set forth in SEQ ID NO: 8, and a CDR3 comprising a sequence set forth in SEQ ID NO: 9; or comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 22, a CDR2 comprising a sequence set forth in SEQ ID NO: 23, and a CDR3 comprising a sequence set forth in SEQ ID NO: 24;(vi) a VL comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 88, a CDR2 comprising a sequence set forth in SEQ ID NO: 91 , and a CDR3 comprising a sequence as set forth in SEQ ID NO: 92; or comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 103, a CDR2 comprising a sequence set forth in SEQ ID NO: 104 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 105;(vii) a VH comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 163, a CDR2 comprising a sequence as set forth in SEQ ID NO: 8, and a CDR3 comprising a sequence as set forth in SEQ ID NO: 9; and a VL comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 88, a CDR2 comprising a sequence as set forth in SEQ ID NO: 91 , and a CDR3 comprising a sequence as set forth in SEQ ID NO: 92; or a VH comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 22, a CDR2 comprising a sequence as set forth in SEQ ID NO: 23 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 24; and a VL comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 103, a CDR2 comprising a sequence as set forth in SEQ ID NO: 104 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 105; or(viii) a VH comprising a sequence as set forth in SEQ ID NO: 81 , and a VL comprising a sequence set forth in SEQ ID NO: 148.

[0052] When the CDRs are determined according to the IMGT system, the antigen binding domain may further comprise at least one of:(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 37, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 38, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 39, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 40, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 113, or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 117, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 118, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 119, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto.

[0053] When the CDRs are determined according to the Kabat system, the antigen binding domain may further comprise at least one of:(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 63, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%,at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 64, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 65, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 66, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 133, or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 137, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 138, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 119, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto.

[0054] In any embodiment, the antigen binding protein comprises a variable heavy chain comprising the amino acid sequence as set forth in SEQ ID NO: 81 , or a sequence at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identical thereto; and a variable light chain comprising the amino acid sequence as set forth in SEQ ID NO: 148; or a sequence at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98 %, or at least about 99%identical thereto; wherein the variable heavy and / or light chains comprise no more than 1 , no more than 2, no more than 3, no more than 4, no more than 5, no more than 6, no more than 7, no more than 8, no more than 9, no more than 10, no more than 11 , no more than 12, no more than 13, no more than 14, no more than 15, no more than 16, no more than 17, no more than 18, no more than 19 or no more than 20 amino acid residue substitutions, deletions, or additions or combination thereof, outside the indicated CDR sequences, and wherein the antigen binding protein retains the ability to bind to CD80.

[0055] In any embodiment, the antigen binding domain comprises:(i) a VH comprising a complementarity determining region (CDR) 1 comprising a sequence as set forth in SEQ ID NO: 10 (IMGT) or 25 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; a CDR2 comprising a sequence as set forth in SEQ ID NO: 11 (IMGT) or 26 or 165 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; and a CDR3 comprising a sequence as set forth in SEQ ID NO: 12 (IMGT) or 27 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(ii) a VH comprising a sequence as set forth in SEQ ID NO: 82 or 84, or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(iii) a VL comprising a complementarity determining region (CDR) 1 comprising a sequence as set forth in SEQ ID NO: 93 (IMGT) or 106 or 166 (Kabat) or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; a CDR2 comprising a sequence as set forth in SEQ ID NO: 91 (IMGT) or 104 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; and a CDR3 comprising a sequence as set forth in SEQ ID NO: 92 (IMGT) or 105 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(iv) a VL comprising a sequence as set forth in SEQ ID NO: 149 or 151 , or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(v) a VH comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 10, a CDR2 comprising a sequence set forth in SEQ ID NO: 11 , and a CDR3 comprising a sequence set forth in SEQ ID NO: 12; or comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 25, a CDR2 comprising a sequence set forth in SEQ ID NO: 26 or 165, and a CDR3 comprising a sequence set forth in SEQ ID NO: 27;(vi) a VL comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 93, a CDR2 comprising a sequence set forth in SEQ ID NO: 91 , and a CDR3 comprising a sequence as set forth in SEQ ID NO: 92; or comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 106 or 166, a CDR2 comprising a sequence set forth in SEQ ID NO: 104 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 105;(vii) a VH comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 10, a CDR2 comprising a sequence as set forth in SEQ ID NO: 11 , and a CDR3 comprising a sequence as set forth in SEQ ID NO: 12 and a VL comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 93, a CDR2 comprising a sequence as set forth inSEQ ID NO: 91 , and a CDR3 comprising a sequence as set forth in SEQ ID NO: 92; or a VH comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 25, a CDR2 comprising a sequence as set forth in SEQ ID NO: 26 or 165 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 27; and a VL comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 106 or 166, a CDR2 comprising a sequence as set forth in SEQ ID NO: 104 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 105;(viii) a VH comprising a sequence as set forth in SEQ ID NO: 82, and a VL comprising a sequence set forth in SEQ ID NO: 149; or(viv) a VH comprising a sequence as set forth in SEQ ID NO: 84, and a VL comprising a sequence set forth in SEQ ID NO: 151.

[0056] When the CDRs are determined according to the IMGT system, the antigen binding domain may further comprise at least one of:(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 41 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 38, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 42, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 43, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 113, or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO:120, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 118, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 121 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto.

[0057] When the CDRs are determined according to the Kabat system, the antigen binding domain may further comprise at least one of:(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 67, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 68, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 69, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 70, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 133, or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 139, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 138, ora sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 121 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto.

[0058] When the CDRs are determined according to the IMGT system, the antigen binding domain may further comprise at least one of:(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 48, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 49, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 50, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 47, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and(ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 125, or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 120, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 126, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence ofSEQ ID NO: 127, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto.

[0059] When the CDRs are determined according to the Kabat system, the antigen binding domain may further comprise at least one of:(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 75, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 76, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 77, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 74, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 143, or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 139, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 144, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 127, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto.

[0060] In any embodiment, the antigen binding protein comprises a variable heavy chain comprising the amino acid sequence as set forth in SEQ ID NO: 82 or 84, or a sequence at least about 80%, at least about 85%, at least about 90%, at least about 91 %, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identical thereto; and a variable light chain comprising the amino acid sequence as set forth in SEQ ID NO: 149 or 151 ; or a sequence at least about 80%, at least about 85%, at least about 90%, at least about 91 %, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98 %, or at least about 99% identical thereto; wherein the variable heavy and / or light chains comprise no more than 1 , no more than 2, no more than 3, no more than 4, no more than 5, no more than 6, no more than 7, no more than 8, no more than 9, no more than 10, no more than 11 , no more than 12, no more than 13, no more than 14, no more than 15, no more than 16, no more than 17, no more than 18, no more than 19 or no more than 20 amino acid residue substitutions, deletions, or additions or combination thereof, outside the indicated CDR sequences, and wherein the antigen binding protein retains the ability to bind to CD80.

[0061] As described herein, the antigen binding protein may be in the form of:(i) a single domain antibody (sdAb);)(ii) a single chain Fv fragment (scFv);(iii) a dimeric scFv (di-scFv); or(iv) one of (i) or (iii) linked to a constant region of an antibody, Fc or a heavy chain constant domain (CH) 2 and / or CH3.

[0062] Further, as described herein, the antigen binding protein may be in the form of:(i) a diabody;(ii) a triabody;(iii) a tetrabody;(iv) a Fab;(v) a F(ab’)2;(vi) a Fv;(vii) a bispecific antibody or other form of multispecific antibody (including a BiTE); or(viii) one of (i) to (vii) linked to a constant region of an antibody, Fc or a heavy chain constant domain (CH) 2 and / or CH3.

[0063] The foregoing antigen binding proteins can also be referred to as antigen binding domains of antibodies.

[0064] Preferably, an antigen binding protein as described herein is an antibody or antigen binding fragment thereof. Typically, the antigen binding protein is an antibody, for example, a monoclonal antibody. The antigen binding protein may be in the form of a recombinant or modified antibody (e.g., chimeric antibody, humanised antibody, human antibody, CDR-grafted antibody, primatised antibody, de-immunised antibody, synhumanised antibody, half-antibody, bispecific antibody, trispecific antibody or multispecific antibody). The antibody may further comprise a chemical modification, such as conjugation to an active agent or radiolabel, or an agent for improving solubility or other modification described herein

[0065] In preferred embodiments, the antigen binding proteins of the invention may be monospecific or multispecific - in other words, they may bind to one or more molecular targets (ie bind to CD80 and optionally another protein target). Preferably, the antigen binding proteins of the invention are monoparatopic, meaning that the antigen binding proteins bind to a single epitope on a given molecular target (ie CD80). For completeness, in preferred embodiments, the antigen binding proteins of the invention are not multiparatopic (in other words, they do not bind to distinct, non-overlapping epitopes on an antigen).

[0066] As used herein the antigen binding protein may be a variable domain.

[0067] As used herein, the complementarity determining region sequences (CDRs) of an antigen binding protein of the invention may be defined according to the IMGT, Chothia or Kabat numbering systems, or any other CDR numbering system known to the skilled person or described herein.

[0068] The invention provides an antigen binding protein as described herein wherein an amino acid sequence forming one or more of FR1 , CDR1 , FR2, CDR2, FR3, CDR3 and FR4 is a human sequence.

[0069] The invention provides an anti-CD80 binding protein, immunoglobulin variable domain, antibody, dab, scFv, Fab, Fab', F(ab')2, Fv fragment, diabody, triabody, linear antibody, single-chain antibody molecule, or multispecific antibody comprising an antigen binding protein having a sequence as described herein, or including a CDR and / or FR sequence as described herein.

[0070] An antigen binding protein as described herein may comprise a human constant region, e.g., an IgG constant region, such as an IgGi, lgG2, IgGs or lgG4 constant region or mixtures thereof. In the case of an antibody or protein comprising a VH and a VL, the VH can be linked to a heavy chain constant region and the VL can be linked to a light chain constant region.

[0071] In one example, an antigen binding protein as described herein comprises a constant region of an lgG4 antibody or a stabilised constant region of an lgG4 antibody. In one example, the protein or antibody comprises an lgG4 constant region with a proline at position 241 (according to the numbering system of Kabat (Kabat et al., Sequences of Proteins of Immunological Interest Washington DC United States Department of Health and Human Services, 1987 and / or 1991)).

[0072] In one example, an antigen binding protein as described herein or a composition of an antigen binding protein as described herein, comprises a heavy chain constant region, comprising a stabilised heavy chain constant region, comprising a mixture of sequences fully or partially with or without the C-terminal lysine residue.

[0073] In one example, an antigen binding protein comprises a H disclosed herein linked or fused to an lgG4 constant region or stabilised lgG4 constant region (e.g., as discussed above) and the VL is linked to or fused to a kappa light chain constant region.

[0074] In any aspect of the present invention, the antibody is a naked antibody. Specifically, the antibody is in a non-conjugated form and is not adapted to form a conjugate.

[0075] The invention provides a fusion protein comprising an antigen binding protein, immunoglobulin variable domain, antibody, dab, scFv, Fab, Fab', F(ab')2, Fv fragment, diabody, triabody, linear antibody, single-chain antibody molecule, or multispecific antibody as described herein.

[0076] The invention also provides a conjugate in the form of an antigen binding protein, immunoglobulin variable domain, antibody, dab, scFv, Fab, Fab', F(ab')2, Fv fragment, diabody, triabody, linear antibody, single-chain antibody molecule, or multispecific antibody or fusion protein as described herein, conjugated to a label or a cytotoxic agent. The cytotoxic agent may be a chemotherapeutic agent or other agent used for the treatment of a disease.

[0077] In another embodiment, the antigen binding protein comprises an Fc region that is engineered to:- increase the in vitro or in vivo half-life;- have an increased capacity to induce antibody-dependent cell mediated cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP) or complement-dependent cytotoxicity;- reduce effector function; or- increase co-engagement of the antigen binding protein.

[0078] In particularly preferred embodiments, the antigen binding proteins of the invention comprise an Fc region engineered to reduce effector function, and in particular comprise a LALA-PG mutant Fc region, or similar, that is unable to bind to Fc receptors and elicit effector function.

[0079] Mutations, deletions or modifications of amino acids in the Fc region which affect half-life, ADCC, ADCP or complement-dependent cytotoxicity, effector function are known to the skilled person and further described herein.

[0080] The functional characteristics of an antigen binding protein of the invention will be taken to apply mutatis mutandis to an antibody of the invention.

[0081] In any aspect of the invention and in any antigen binding protein described herein, there further includes an Fc region that is engineered to have reduced capacity to induce antibody-dependent cell-mediated cytotoxicity (ADCC). Preferably, the reduced capacity to induce ADCC is conferred by mutation, deletion or modification of amino acids in the Fc region which interact with an Fc receptor.

[0082] In aspects of the invention directed to multiple polypeptide chains that form an antigen binding protein, an expression construct comprises a nucleic acid encoding a polypeptide comprising, e.g., a VH operably linked to a promoter and a nucleic acid encoding a polypeptide comprising, e.g., a VL operably linked to a promoter.

[0083] In another example, the expression construct is a bicistronic expression construct, e.g., comprising the following operably linked components in 5’ to 3’ order:(i) a promoter(ii) a nucleic acid encoding a first polypeptide;(iii) an internal ribosome entry site; and(iv) a nucleic acid encoding a second polypeptide, wherein the first polypeptide comprises a VH and the second polypeptide comprises a VL, or vice versa.

[0084] The present invention also contemplates separate expression constructs one of which encodes a first polypeptide comprising a VH and another of which encodes a second polypeptide comprising a VL. For example, the present invention also provides a composition comprising:(i) a first expression construct comprising a nucleic acid encoding a polypeptide comprising a VH operably linked to a promoter; and(ii) a second expression construct comprising a nucleic acid encoding a polypeptide comprising a VL operably linked to a promoter.

[0085] The invention provides a cell comprising a vector or nucleic acid described herein. Preferably, the cell is isolated, substantially purified or recombinant. In one example, the cell comprises the expression construct of the invention or:(i) a first expression construct comprising a nucleic acid encoding a polypeptide comprising a VH operably linked to a promoter; and(ii) a second expression construct comprising a nucleic acid encoding a polypeptide comprising a VL operably linked to a promoter, wherein the first and second polypeptides associate to form an antigen binding protein of the present invention.

[0086] Examples of cells of the present invention include bacterial cells, yeast cells, insect cells or mammalian cells.

[0087] The invention provides a nucleic acid encoding an antigen binding protein, immunoglobulin variable domain, antibody, dab, scFv, Fab, Fab', F(ab')2, Fv fragment, diabody, triabody, linear antibody, single-chain antibody molecule, or multispecific antibody, fusion protein or conjugate as described herein.

[0088] The invention provides a vector comprising a nucleic acid described herein.

[0089] The invention provides a cell comprising a vector or nucleic acid described herein.

[0090] The invention provides a pharmaceutical composition comprising an antigen binding protein, or including a CDR and / or FR sequence as described herein, or an immunoglobulin variable domain, antibody, dab, scFv, Fab, Fab', F(ab')2, Fv fragment, diabody, triabody, linear antibody, single-chain antibody molecule, or multispecific antibody, fusion protein, or conjugate as described herein and a pharmaceutically acceptable carrier, diluent or excipient.

[0091] The invention provides a diagnostic composition comprising an antigen binding protein, or including a CDR and / or FR sequence as described herein, or antigen binding protein, immunoglobulin variable domain, antibody, dab, scFv, Fab, Fab', F(ab')2, Fv fragment, diabody, triabody, linear antibody, single-chain antibody molecule, ormultispecific antibody, fusion protein or conjugate as described herein, a diluent and optionally a label.

[0092] The invention provides a kit or article of manufacture comprising an antigen binding protein, or including a CDR and / or FR sequence as described herein or an immunoglobulin variable domain, antibody, dab, scFv, Fab, Fab', F(ab')2, Fv fragment, diabody, triabody, linear antibody, single-chain antibody molecule, or multispecific antibody, fusion protein or conjugate as described herein.

[0093] The invention provides use of a sequence according to one or more of CDR1 , CDR2, FR1 , FR2, FR3 and FR4 as described herein to produce an antigen binding protein for binding to a CD80.

[0094] The invention provides use of an antigen binding protein or a CDR and / or FR sequence as described herein to produce an anti-CD80 antigen binding protein having increased affinity for CD80.

[0095] The invention provides a library of nucleic acid molecules produced from the mutation of an antigen binding protein or a CDR and / or FR sequence as described herein, wherein at least one nucleic acid molecule in said library encodes an antigen binding protein for binding to CD80.

[0096] The invention provides a method for producing an antigen binding protein for binding to CD80 as described herein comprising expressing a nucleic acid as described herein in a cell or animal as described herein.

[0097] An antigen binding protein as described herein may be purified, substantially purified, isolated and / or recombinant.

[0098] An antigen binding protein of the invention may be part of a supernatant taken from media in which a hybridoma expressing an antigen binding protein of the invention has been grown.

[0099] Further, the present invention provides a pharmaceutical composition comprising an antigen binding protein of the invention, and a physiologically or pharmaceutically acceptable carrier or diluent.

[0100] The present invention further contemplates therapeutic and diagnostic uses for an antigen binding protein of the invention. The antigen binding proteins of the invention are preferably used to treat an immune related disorder. In the most preferred embodiments of the invention, the antigen binding proteins described herein are used to treat Crohn's disease, systemic lupus erythematosus (SLE), lupus nephritis, psoriatic arthritis, psoriasis, rheumatoid arthritis, ulcerative colitis, and / or transplant rejection.

[0101] Accordingly, the present invention provides a method of treating an inflammatory disorder in a subject in need thereof, the method comprising administering to said subject, an antigen binding protein or pharmaceutical composition of the invention, thereby treating an inflammatory disorder in the subject.

[0102] Further, the present invention provides for use of an antigen binding protein as described herein, in the manufacture of a medicament for the treatment of an inflammatory disorder or a condition or disorder requiring immunosuppression in a subject.

[0103] The present invention also provides an antigen binding protein or pharmaceutical composition as described herein, for use in the treatment of an inflammatory disorder or a condition or disorder requiring immunosuppression.

[0104] As used herein, except where the context requires otherwise, the term "comprise" and variations of the term, such as "comprising", "comprises" and "comprised", are not intended to exclude further additives, components, integers or steps. The terms “comprising’ and “including” are used interchangeably.

[0105] Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

[0106] As used herein, except where the context requires otherwise, the term "comprise" and variations of the term, such as "comprising", "comprises" and "comprised", are not intended to exclude further additives, components, integers or steps.

[0107] Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.Brief description of the drawings

[0108] Figure 1 : (A) Flow cytometry of cis-CD80:PD-L1 cells comparing abatacept and B10 binding to CD80 (hlgG1 staining), effect on cis-bound PD-L1 (MIH1 staining), and ability to block co-stimulation (CD28-lg binding). (B) Binding of high-affinity CTLA4-lg (CTLA4HA-lg; high affinity CD28 surrogate) to cells expressing surface CD80 in competition with a dose / response of abatacept and B10, showing improved CTLA4HA-lg displacement by B10 relative to abatacept.

[0109] Figure 2: Flow cytometry readouts for the CD80 antibodies 2B2, B10, 2B17, and 2B26 compared to abatacept and TKMF5. The CD80 binding (hlgG1 staining), effect on cis-bound PD-L1 (free PD-L1 by MIH1 staining), and CD28 blockade (percent of CD28- Fc binding blocked) on cis-CD80:PD-L1 cells is shown. These novel CD80 antibodies block CD28 binding with minor impact on c / s-bound PD-L1.

[0110] Figure 3: Flow cytometry of CD28-lg binding (mlgG2a staining) on cis- CD80:PD-L1 cells. Binding is completely blocked by treatment with abatacept or B10, and only partially blocked by galiximab. B10 and galiximab were produced in crude supernatant, and differences in blockade may represent differences in both affinity and antibody production.

[0111] Figure 4: (A) In vitro primary human T cell activation as assessed by the percentage of IL-2+ T cells following 4 day co-culture with artificial antigen presenting cells (aAPCs) expressing a 1 :1 ratio of CD80:PD-L1 and cell surface OKT3scFv. 50 pg / mL of abatacept or B10 were added in the final 8 hours of co-culture. (B) A dose / response of the experimental conditions described in A, showing reduced CD4 and CD8 T cell activity by B10 relative to abatacept. (C) Activity in CD4 T cells treated as described in A, demonstrating partial contribution of PD-1 signalling by abatacept by addition of an anti-PD-1 antibody (nivolumab). T cell suppression by B10 is independent of PD-1 signalling.

[0112] Figure 5: A) Schematic of the humanisation strategy for mouse CD80 and PD- L1 genes. Homologous human sequences replace exon 2 of mouse CD80, which encodes the IgV domain bound by the human CD80 antibodies, and exon 3 of mouse PD-L1. Double knockin (DKI) mice maintain endogenous regulation and expression CD80 and PD-L1 , and retain binding in cis to each other as well as in trans to CD28, CTLA4, or PD-1. (B) Schematic of the anti-GBM glomerulonephritis mouse model of kidney autoimmunity. (C) Kidney damage measured by the urine albumin:creatinine ratio (uACR) showing improved protection by B10 relative to abatacept.Sequence information

[0113] Tables comprising sequence information:

[0114] Table 1 : VH CDR sequences - antigen binding proteins inhibiting binding ofCD28 to CD80

[0115] Table 2: VH framework (FR) sequences - antigen binding proteins inhibiting binding of CD28 to CD80

[0116] Table 3: VH full sequences - antigen binding proteins inhibiting binding of CD28 to CD80

[0117] Table 4: VL CDR sequences - antigen binding proteins inhibiting binding ofCD28 to CD80

[0118] Table 5: VL framework sequences - antigen binding proteins inhibiting binding ofCD28 to CD80

[0119] Table 6: VL full sequences - antigen binding proteins inhibiting binding of CD28 to CD80Detailed description of the embodiments

[0120] It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

[0121] Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

[0122] Reference will now be made in detail to certain embodiments of the invention. While the invention will be described in conjunction with the embodiments, it will be understood that the intention is not to limit the invention to those embodiments. On the contrary, the invention is intended to cover all alternatives, modifications, and equivalents, which may be included within the scope of the present invention as defined by the claims.

[0123] One skilled in the art will recognize many methods and materials similar or equivalent to those described herein, which could be used in the practice of the present invention. The present invention is in no way limited to the methods and materials described. It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

[0124] All of the patents and publications referred to herein are incorporated by reference in their entirety.

[0125] For purposes of interpreting this specification, terms used in the singular will also include the plural and vice versa.

[0126] The general chemical terms used in the formulae herein have their usual meaning.

[0127] CD80 (B7-1) and CD86 (B7-2) are costimulatory ligands expressed on the surface of antigen-presenting cells (APCs). Upon APC interactions with naive T cells, APC surface CD80 and CD86 bind the T cell surface receptor CD28 to provide costimulatory signals required for full T cell activation. Blockade of CD80:CD28 interactions can therefore suppress T cell activity, with potential therapeutic utility in autoimmune and inflammatory diseases. This has been validated in several mouse models using antibodies targeting mouse CD80.

[0128] Anti-CD80 antibodies that block human CD80:CD28 interactions have previously been tested in clinical trials for autoimmune disease. For example, the anti-CD80 antibody galiximab was trialled in psoriasis. Notably, galiximab failed in trials in both autoimmunity and cancer.

[0129] CTLA4-lg fusion proteins including abatacept and belatacept block CD80:CD28 and CD86:CD28 interactions, and are clinically approved immunosuppressive therapies in a range of autoimmune and inflammatory diseases. Notably, these therapeutics do not engage Fc effector functions and therefore act as “blocking” rather than “clearance” agents.

[0130] The present invention relates to a series of novel anti-human CD80 antibodies that block CD80:CD28 interactions. The inventors show that exemplary antibodies of the invention suppress primary human T cell activation in vitro, and alleviate disease in an in vivo mouse model of autoimmune / inflammatory kidney disease. Critically, the antibodies of the invention are believed to have increased affinity for CD80 compared to a prior art antibody, galiximab, while also blocking CD80:CD28 with far greater potency than the CTLA-lg fusions protein abatacept.

[0131] The novel antibodies of the invention are therefore believed to be useful immunosuppressants in vivo and useful for the treatment for a range of autoimmune diseases and / or conditions requiring reduction or prevention of inflammation.General

[0132] Throughout this specification, unless specifically stated otherwise or the context requires otherwise, reference to a single step, composition of matter, group of steps or group of compositions of matter shall be taken to encompass one and a plurality (i.e. one or more) of those steps, compositions of matter, groups of steps or groups of compositions of matter. Thus, as used herein, the singular forms “a”, “an” and “the” include plural aspects, and vice versa, unless the context clearly dictates otherwise. For example, reference to “a” includes a single as well as two or more; reference to “an” includes a single as well as two or more; reference to “the” includes a single as well as two or more and so forth.

[0133] Those skilled in the art will appreciate that the present invention is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps, features, compositions and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations or any two or more of said steps or features.

[0134] One skilled in the art will recognize many methods and materials similar or equivalent to those described herein, which could be used in the practice of the present invention. The present invention is in no way limited to the methods and materials described.

[0135] All of the patents and publications referred to herein are incorporated by reference in their entirety.

[0136] The present invention is not to be limited in scope by the specific examples described herein, which are intended for the purpose of exemplification only. Functionally- equivalent products, compositions and methods are clearly within the scope of the present invention.

[0137] Any example or embodiment of the present invention herein shall be taken to apply mutatis mutandis to any other example or embodiment of the invention unless specifically stated otherwise.

[0138] Unless specifically defined otherwise, all technical and scientific terms used herein shall be taken to have the same meaning as commonly understood by one of ordinary skill in the art (for example, in cell culture, molecular genetics, immunology, immunohistochemistry, protein chemistry, and biochemistry).

[0139] Unless otherwise indicated, the recombinant protein, cell culture, and immunological techniques utilized in the present disclosure are standard procedures, well known to those skilled in the art. Such techniques are described and explained throughout the literature in sources such as, J. Perbal, A Practical Guide to Molecular Cloning, John Wiley and Sons (1984), J. Sambrook et al. Molecular Cloning: A Laboratory Manual, Cold Spring Harbour Laboratory Press (1989), T.A. Brown (editor), Essential Molecular Biology: A Practical Approach, Volumes 1 and 2, IRL Press (1991), D.M. Glover and B.D. Hames (editors), DNA Cloning: A Practical Approach, Volumes 1-4, IRL Press (1995 and 1996), and F.M. Ausubel et al. (editors), Current Protocols in Molecular Biology, Greene Pub. Associates and Wiley-lnterscience (1988, including all updates until present), Ed Harlow and David Lane (editors) Antibodies: A Laboratory Manual, Cold Spring Harbour Laboratory, (1988), and J.E. Coligan et al. (editors) Current Protocols in Immunology, John Wiley & Sons (including all updates until present).

[0140] The description and definitions of variable regions and parts thereof, immunoglobulins, antibodies and fragments thereof herein may be further clarified by the definitions provided further herein.

[0141] The term “and / or”, e.g., “X and / or Y” shall be understood to mean either “X and Y” or “X or Y” and shall be taken to provide explicit support for both meanings or for either meaning.

[0142] As used herein the term "derived from" shall be taken to indicate that a specified integer may be obtained from a particular source albeit not necessarily directly from that source.

[0143] Reference herein to a range of, e.g., residues, will be understood to be inclusive. For example, reference to “a region comprising amino acids 56 to 65” will be understood in an inclusive manner, i.e., the region comprises a sequence of amino acids as numbered 56, 57, 58, 59, 60, 61 , 62, 63, 64 and 65 in a specified sequence.Selected Definitions

[0144] The term "isolated protein" or "isolated polypeptide" is a protein or polypeptide that by virtue of its origin or source of derivation is not associated with naturally- associated components that accompany it in its native state; is substantially free of other proteins from the same source. A protein may be rendered substantially free of naturally associated components or substantially purified by isolation, using protein purification techniques known in the art. By “substantially purified” is meant the protein is substantially free of contaminating agents, e.g., at least about 70% or 75% or 80% or 85% or 90% or 95% or 96% or 97% or 98% or 99% free of contaminating agents.

[0145] The term “recombinant” shall be understood to mean the product of artificial genetic recombination. Accordingly, in the context of a recombinant protein comprising an antibody antigen binding domain, this term does not encompass an antibody naturally- occurring within a subject’s body that is the product of natural recombination that occurs during B cell maturation. However, if such an antibody is isolated, it is to be considered an isolated protein comprising an antibody antigen binding domain. Similarly, if nucleic acid encoding the protein is isolated and expressed using recombinant means, the resulting protein is a recombinant protein comprising an antibody antigen binding domain. A recombinant protein also encompasses a protein expressed by artificial recombinant means when it is within a cell, tissue or subject, e.g., in which it is expressed.

[0146] The term “protein” shall be taken to include a single polypeptide chain, i.e., a series of contiguous amino acids linked by peptide bonds or a series of polypeptide chains covalently or non-covalently linked to one another (i.e., a polypeptide complex). For example, the series of polypeptide chains can be covalently linked using a suitable chemical or a disulphide bond. Examples of non-covalent bonds include hydrogen bonds, ionic bonds, Van der Waals forces, and hydrophobic interactions.

[0147] The term “polypeptide” or “polypeptide chain” will be understood from the foregoing paragraph to mean a series of contiguous amino acids linked by peptide bonds.

[0148] As used herein, the term “antigen binding protein” is used interchangeably with “antigen binding domain” and shall be taken to mean a region of an antibody that is capable of specifically binding to an antigen, i.e. , a VH or a VL or an Fv comprising both a VH and a VL. The antigen binding domain need not be in the context of an entire antibody, e.g., it can be in isolation (e.g., a domain antibody) or in another form, e.g., as described herein, such as a scFv.

[0149] For the purposes for the present disclosure, the term “antibody” includes a protein capable of specifically binding to one or a few closely related antigens by virtue of an antigen binding domain contained within a Fv. This term includes four chain antibodies (e.g., two light chains and two heavy chains), recombinant or modified antibodies (e.g., chimeric antibodies, humanized antibodies, human antibodies, CDR-grafted antibodies, primatized antibodies, de-immunized antibodies, synhumanized antibodies, halfantibodies, bispecific antibodies). An antibody generally comprises constant domains, which can be arranged into a constant region or constant fragment or fragment crystallizable (Fc). Exemplary forms of antibodies comprise a four-chain structure as their basic unit. Full-length antibodies comprise two heavy chains (~50 to 70 kD) covalently linked and two light chains (~23 kDa each). A light chain generally comprises a variable region (if present) and a constant domain and in mammals is either a K light chain or a A light chain. A heavy chain generally comprises a variable region and one or two constant domain(s) linked by a hinge region to additional constant domain(s). Heavy chains of mammals are of one of the following types a, 5, E, y, or p. Each light chain is also covalently linked to one of the heavy chains. For example, the two heavy chains and the heavy and light chains are held together by inter-chain disulfide bonds and by non- covalent interactions. The number of inter-chain disulfide bonds can vary among different types of antibodies. Each chain has an N-terminal variable region (VH or VL wherein each are -110 amino acids in length) and one or more constant domains at the C- terminus. The constant domain of the light chain (CL which is -110 amino acids in length) is aligned with and disulfide bonded to the first constant domain of the heavy chain (CH1 which is 330 to 440 amino acids in length). The light chain variable region is aligned with the variable region of the heavy chain. The antibody heavy chain can comprise 2 or moreadditional CH domains (such as, CH2, CH3 and the like) and can comprise a hinge region between the CH1 and CH2 constant domains. Antibodies can be of any type (e.g., IgG, IgE, IgM, IgD, IgA, and IgY), class (e.g., lgG1 , lgG2, lgG3, lgG4, lgA1 and lgA2) or subclass. In one example, the antibody is a murine (mouse or rat) antibody or a primate (such as, human) antibody. In one example the antibody heavy chain is missing a C- terminal lysine residue. In one example, the antibody is humanized, synhumanized, chimeric, CDR-grafted or deimmunized.

[0150] The terms "full-length antibody", "intact antibody" or "whole antibody" are used interchangeably to refer to an antibody in its substantially intact form, as opposed to an antigen binding fragment of an antibody. Specifically, whole antibodies include those with heavy and light chains including an Fc region. The constant domains may be wild-type sequence constant domains (e.g., human wild-type sequence constant domains) or amino acid sequence variants thereof.

[0151] As used herein, “variable region” refers to the portions of the light and / or heavy chains of an antibody as defined herein that is capable of specifically binding to an antigen and, includes amino acid sequences of complementarity determining regions (CDRs); i.e., CDR1 , CDR2, and CDR3, and framework regions (FRs). For example, the variable region comprises three or four FRs (e.g., FR1 , FR2, FR3 and optionally FR4) together with three CDRs. VH refers to the variable region of the heavy chain. VL refers to the variable region of the light chain.

[0152] As used herein, the term “subject” shall be taken to mean any animal including humans, for example a mammal. Exemplary subjects include but are not limited to humans and non-human primates. For example, the subject is a human.

[0153] “Antibodies” or “immunoglobulins” or “Igs” are gamma globulin proteins that are found in blood, or other bodily fluids of vertebrates that function in the immune system to bind antigen, hence identifying and neutralizing foreign objects.

[0154] Antibodies are generally a heterotetrameric glycoprotein composed of two identical light (L) chains and two identical heavy (H) chains. Each L chain is linked to a H chain by one covalent disulfide bond. The two H chains are linked to each other by oneor more disulfide bonds depending on the H chain isotype. Each H and L chain also has regularly spaced intrachain disulfide bridges.

[0155] H and L chains define specific Ig domains. More particularly, each H chain has at the N-terminus, a variable domain (VH) followed by three constant domains (CH) for each of the a and y chains and four CH domains for p and E isotypes. Each L chain has at the N-terminus, a variable domain (V L) followed by a constant domain (CL) at its other end. The VL is aligned with the VH and the CL is aligned with the first constant domain of the heavy chain (CH1).

[0156] Antibodies can be assigned to different classes or isotypes. There are five classes of immunoglobulins: IgA, IgD, IgE, IgG, and IgM, having heavy chains designated a, 5, E, Y, and p, respectively. The y and a classes are further divided into subclasses on the basis of relatively minor differences in CH sequence and function, e.g., humans express the following subclasses: lgG1 , lgG2, lgG3, lgG-4, lgA1 , and lgA2. The L chain from any vertebrate species can be assigned to one of two clearly distinct types, called kappa and lambda, based on the amino acid sequences of their constant domains.

[0157] The constant domain includes the Fc portion which comprises the carboxyterminal portions of both H chains held together by disulfides. The effector functions of antibodies such as ADCC are determined by sequences in the Fc region, which region is also the part recognized by Fc receptors (FcR) found on certain types of cells.

[0158] The pairing of a VH and VL together forms a "variable region" or "variable domain" including the amino -terminal domains of the heavy or light chain of the antibody. The variable domain of the heavy chain may be referred to as "VH." The variable domain of the light chain may be referred to as "VL." The V domain contains an antigen binding protein which affects antigen binding and defines specificity of a particular antibody for its particular antigen. V regions span about 110 amino acid residues and consist of relatively invariant stretches called framework regions (FRs) (generally about 4) of 15-30 amino acids separated by shorter regions of extreme variability called "hypervariable regions" (generally about 3) that are each 9-12 amino acids long. The FRs largely adopt a p-sheet configuration and the hypervariable regions form loops connecting, and in some cases forming part of, the p-sheet structure.

[0159] "Hypervariable region", "HVR", or "HV" refers to the regions of an antibody variable domain which are hypervariable in sequence and / or form structurally defined loops. Generally, antibodies comprise six hypervariable regions; three in the VH (H1 , H2, H3), and three in the VL (L1 , L2, L3). A number of hypervariable region delineations are in use and are encompassed herein.

[0160] As used herein, the term “complementarity determining regions” (syn. CDRs; i.e., CDR1 , CDR2, and CDR3) refers to the amino acid residues of an antibody variable region the presence of which are major contributors to specific antigen binding. Each variable region domain (VH or VL) typically has three CDRs identified as CDR1 , CDR2 and CDR3. The CDRs of VH are also referred to herein as CDR H1 , CDR H2 and CDR H3, respectively, wherein CDR H1 corresponds to CDR 1 of VH, CDR H2 corresponds to CDR 2 of VH and CDR H3 corresponds to CDR 3 of VH. (Alternatively, the CDRs may be named HCDR1 , HCDR2 and HCDR3). Likewise, the CDRs of VL are referred to herein as CDR L1 , CDR L2 and CDR L3, respectively, wherein CDR L1 corresponds to CDR 1 of VL, CDR L2 corresponds to CDR 2 of VL and CDR L3 corresponds to CDR 3 of VL. (Alternatively, the CDRs in the light variable region may be named LCDR1 , LCDR2 and LCDR3)

[0161] "Framework" or "FR" residues are those variable domain residues other than the hypervariable region or CDR residues herein defined. The FRs of VH are also referred to herein as FR H1 , FR H2, FR H3 and FR H4, respectively, wherein FR H1 corresponds to FR 1 of VH, FR H2 corresponds to FR 2 of VH, FR H3 corresponds to FR 3 of VH and FR H4 corresponds to FR 4 of VH. Likewise, the FRs of VL are referred to herein as FR L1 , FR L2, FR L3 and FR L4, respectively, wherein FR L1 corresponds to FR 1 of VL, FR L2 corresponds to FR 2 of VL, FR L3 corresponds to FR 3 of VL and FR L4 corresponds to FR 4 of VL.

[0162] In any embodiment, the amino acid positions assigned to CDRs and FRs may be defined according to Kabat Sequences of Proteins of Immunological Interest, National Institutes of Health, Bethesda, Md., 1987 and 1991 (also referred to herein as “the Kabat numbering system”). It will be appreciated that in accordance with the present invention, the system used to define FRs and CDRs is not limited to the Kabat numbering system, but includes all numbering systems, including the canonical numbering system of Chothiaand Lesk J. Mol. Biol. 196: 901-917, 1987; Chothia et al., Nature 342: 877-883, 1989; and / or Al-Lazikani et al., J. Mol. Biol. 273: 927-948, 1997; the numbering system of Honnegher and Plukthun J. Mol. Biol. 309: 657-670, 2001 ; or the IMGT system discussed in Giudicelli et al., Nucleic Acids Res. 25: 206-211 1997. In another example, the amino acid positions assigned to CDRs and FRs may be defined according to the Martin (Enhanced Chothia) Numbering Scheme (http: / / www.bioinfo.org.uk / abs / info.html). In some examples, the CDRs may be defined according to the AbM numbering system. The AbM system represents a compromise between the Kabat and Chothia structural loops, and is used by Oxford Molecular's AbM antibody-modeling software. In some examples, the CDRs may be “contact” CDRs. The “contact” CDRs are based on an analysis of the available complex crystal structures.

[0163] In one example, the CDRs are defined according to the Kabat numbering system. Optionally, heavy chain CDR2 according to the Kabat numbering system does not comprise the five C-terminal amino acids listed herein or any one or more of those amino acids are substituted with another naturally-occurring amino acid. In this regard, Padlan et al., FASEB J., 9: 133-139, 1995 established that the five C-terminal amino acids of heavy chain CDR2 are not generally involved in antigen binding.

[0164] The different systems used for assigning CDRs and FRs of an antigen binding domain are well known to the skilled person and are summarised in the below table:

[0165] 1Some of these definitions (particularly for Chothia loops) vary depending on the individual publication examined.

[0166] 2The end of the Chothia CDR H1 loop when numbered using the Kabat numbering convention varies between H32 and H34 depending on the length of the loop. This is because the Kabat numbering scheme places the insertions at H35A and H35B: if neither H35A nor H35B is present, the loop ends at H32; if only H35A is present, the loop ends at H33; if both H35A and H35B are present, the loop ends at H34.

[0167] “A peptide for forming an antigen binding protein” generally refers to a peptide that may form a conformation that confers the specificity of an antibody for antigen. Examples include whole antibody or whole antibody related structures, whole antibody fragments including a variable domain, variable domains and fragments thereof, including light and heavy chains, or fragments of light and heavy chains that include some but not all of hypervariable regions or constant regions.

[0168] An "intact" or “whole” antibody is one which comprises an antigen-binding protein as well as a CL and at least heavy chain constant domains, CH1 , CH2 and CH3. The constant domains may be native sequence constant domains (e.g. human native sequence constant domains) or amino acid sequence variant thereof.

[0169] “Whole antibody related structures” include multimerized forms of whole antibody.

[0170] “Whole antibody fragments including a variable domain” include Fab, Fab', F(ab')2, and Fv fragments; diabodies; linear antibodies, single-chain antibody molecules; and multispecific antibodies formed from antibody fragments.

[0171] The Fab fragment consists of an entire L chain along with the variable region domain of the H chain (VH), and the first constant domain of one heavy chain (CHI). Each Fab fragment is monovalent with respect to antigen binding, i.e., it has a single antigenbinding protein.

[0172] A Fab' fragment differs from Fab fragments by having additional few residues at the carboxy terminus of the CHI domain including one or more cysteines from theantibody hinge region. Fab'- SH is the designation herein for Fab' in which the cysteine residue(s) of the constant domains bear a free thiol group.

[0173] A F(ab')2 fragment roughly corresponds to two disulfide linked Fab fragments having divalent antigen-binding activity and is still capable of cross-linking antigen.

[0174] An "Fv" is an antibody fragment which contains a complete antigen-recognition and - binding site. This fragment consists of a dimer of one heavy- and one light-chain variable region domain in tight, non-covalent association.

[0175] In a single-chain Fv (scFv) species, one heavy- and one light-chain variable domain can be covalently linked by a flexible peptide linker such that the light and heavy chains can associate in a "dimeric" structure analogous to that in a two-chain Fv species. From the folding of these two domains emanate six hypervariable loops (3 loops each from the H and L chain) that contribute the amino acid residues for antigen binding and confer antigen binding specificity to the antibody.

[0176] "Single-chain Fv" also abbreviated as "sFv" or "scFv" are antibody fragments that comprise the VH and VL antibody domains connected to form a single polypeptide chain. Preferably, the scFv polypeptide further comprises a polypeptide linker between the VH and VL domains which enables the scFv to form the desired structure for antigen binding.

[0177] A “single variable domain” is half of an Fv (comprising only three CDRs specific for an antigen) that has the ability to recognize and bind antigen, although at a lower affinity than the entire binding site.

[0178] "Diabodies" refers to antibody fragments with two antigen-binding sites, which fragments comprise a heavy-chain variable domain (VH) connected to a light-chain variable domain (VL) in the same polypeptide chain (VH-VL). The small antibody fragments are prepared by constructing sFv fragments (see preceding paragraph) with short linkers (about 5-10 residues) between the VH and VL domains such that interchain but not intra-chain pairing of the V domains is achieved, resulting in a bivalent fragment, i.e. , fragment having two antigen-binding sites.

[0179] Diabodies may be bivalent or bispecific. Bispecific diabodies are heterodimers of two "crossover" sFv fragments in which the VH and VL domains of the two antibodies are present on different polypeptide chains. Triabodies and tetrabodies are also generally known in the art.

[0180] An "isolated antibody" is one which has been identified and separated and / or recovered from a component of its pre-existing environment. Contaminant components are materials that would interfere with therapeutic uses for the antibody, and may include enzymes, hormones, and other proteinaceous or nonproteinaceous solutes.

[0181] A "human antibody" refers to an antibody which possesses an amino acid sequence which corresponds to that of an antibody produced by a human and / or has been made using any of the techniques for making human antibodies as disclosed herein. This definition of a human antibody specifically excludes a humanized antibody comprising non-human antigen-binding residues. Human antibodies can be produced using various techniques known in the art, including phage -display libraries. Human antibodies can be prepared by administering the antigen to a transgenic animal that has been modified to produce such antibodies in response to antigenic challenge, but whose endogenous loci have been disabled.

[0182] "Humanized" forms of non-human (e.g., rodent) antibodies are chimeric antibodies that contain minimal sequence derived from the non-human antibody. For the most part, humanized antibodies are human immunoglobulins (recipient antibody) in which residues from a hypervariable region of the recipient are replaced by residues from a hypervariable region of a non-human species (donor antibody) such as mouse, rat, rabbit or non-human primate having the desired antibody specificity, affinity, and capability. In some instances, framework region (FR) residues of the human immunoglobulin are replaced by corresponding non-human residues. Furthermore, humanized antibodies may comprise residues that are not found in the recipient antibody or in the donor antibody. These modifications are made to further refine antibody performance. In general, the humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the hypervariable loops correspond to those of a non-human immunoglobulin and all or substantially all of the FRs are those of a human immunoglobulin sequence. Thehumanized antibody optionally also will comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin.

[0183] "Monoclonal antibody" refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies comprising the population are identical except for possible naturally occurring mutations that may be present in minor amounts. Monoclonal antibodies are highly specific, being directed against a single antigenic site or determinant on the antigen. In addition to their specificity, the monoclonal antibodies are advantageous in that they may be synthesized uncontaminated by other antibodies. Monoclonal antibodies may be prepared by the hybridoma methodology, or may be made using recombinant DNA methods in bacterial, eukaryotic animal or plant cells. The "monoclonal antibodies" may also be isolated from phage antibody libraries.

[0184] The monoclonal antibodies herein include "chimeric" antibodies in which a portion of the heavy and / or light chain is identical with or homologous to corresponding sequences in antibodies derived from a particular species or belonging to a particular antibody class or subclass, while the remainder of the chain(s) is identical with or homologous to corresponding sequences in antibodies derived from another species or belonging to another antibody class or subclass, as well as fragments of such antibodies, so long as they exhibit the desired biological activity. Chimeric antibodies of interest herein include "primatized" antibodies comprising variable domain antigen-binding sequences derived from a non-human primate (e.g. Old World Monkey, Ape etc), and human constant region sequences.

[0185] The term "anti-CD80 antibody" or "an antibody that binds to CD80" or “CD80 binding protein or antibody” refers to a protein or an antibody that is capable of binding CD80 with sufficient affinity such that the antibody is useful as a diagnostic and / or therapeutic agent in targeting proteins or cells expressing or presenting CD80. Preferably, the extent of binding of an anti-CD80 antibody to an unrelated tag or protein is less than about 10% of the binding of the antibody to CD80 as measured, e.g., by a radioimmunoassay (RIA). In certain embodiments, an antibody that binds to CD80 has a dissociation constant (Kd) of < 1 pM, < 100 nM, < 10 nM, < 1 nM, or < 0.1 nM.

[0186] "Binding affinity" generally refers to the strength of the sum total of noncovalent interactions between a single binding site of a molecule (e.g., an antibody) and its binding partner (e.g., an antigen). Generally, "binding affinity" refers to intrinsic binding affinity which reflects a 1 : 1 interaction between members of a binding pair (e.g., antibody and antigen). The affinity of a molecule X for its partner Y can generally be represented by the dissociation constant (Kd). Affinity can be measured by common methods known in the art, including those described herein. Low-affinity antibodies generally bind antigen slowly and tend to dissociate readily, whereas high-affinity antibodies generally bind antigen faster and tend to remain bound longer. A variety of methods of measuring binding affinity are known in the art, any of which can be used for purposes of the present invention.

[0187] As used herein, the term “binds” in reference to the interaction of an antigen binding protein or an antigen binding domain thereof with an antigen means that the interaction is dependent upon the presence of a particular structure (e.g., an antigenic determinant or epitope) on the antigen. For example, an antibody recognizes and binds to a specific protein structure rather than to proteins generally. If an antibody binds to epitope "A", the presence of a molecule containing epitope “A” (or free, unlabelled “A”), in a reaction containing labeled “A” and the protein, will reduce the amount of labelled “A” bound to the antibody.

[0188] As used herein, the term “specifically binds” or “binds specifically” shall be taken to mean that an antigen binding protein of the invention reacts or associates more frequently, more rapidly, with greater duration and / or with greater affinity with a particular antigen or cell expressing same than it does with alternative antigens or cells.

[0189] As used herein, the term “does not detectably bind” shall be understood to mean that an antigen binding protein, e.g., an antibody, binds to a candidate antigen at a level less than 10%, or 8% or 6% or 5% above background. The background can be the level of binding signal detected in the absence of the protein and / or in the presence of a negative control protein (e.g., an isotype control antibody) and / or the level of binding detected in the presence of a negative control antigen. The level of binding is detected using biosensor analysis (e.g. Biacore) in which the antigen binding protein is immobilized and contacted with an antigen.

[0190] As used herein, the term “does not significantly bind” shall be understood to mean that the level of binding of an antigen binding protein of the invention to a polypeptide is not statistically significantly higher than background, e.g., the level of binding signal detected in the absence of the antigen binding protein and / or in the presence of a negative control protein (e.g., an isotype control antibody) and / or the level of binding detected in the presence of a negative control polypeptide. The level of binding is detected using biosensor analysis (e.g. Biacore) in which the antigen binding protein is immobilized and contacted with an antigen.

[0191] An "affinity matured" antibody is one with one or more alterations in one or more HVRs thereof which result in an improvement in the affinity of the antibody for antigen, compared to a parent antibody which does not possess those alteration(s). Preferred affinity matured antibodies will have nanomolar or even picomolar affinities for the target antigen. Affinity matured antibodies are produced by procedures known in the art.

[0192] "ADCC" refers to a process called antibody-dependent cellular cytotoxicity, which is an immune response mediated primarily by natural killer (NK) cells in humans. In ADCC, FcyRIII on the surface of an NK cell recognizes the Fe region of antibody that is bound to antigen displayed on the surface of a target cell. This activates the NK cell, which releases perforins and granzymes, leading to lysis and apoptosis of the target cells.

[0193] "CDC" refers to a complex process called complement-dependent cytotoxicity that can lead to cell killing through the action of a cascade of proteins that can act through either of two major pathways.

[0194] "ADCP" refers to a process called antibody dependent cell-mediated phagocytosis. In this Fe receptor-mediated process, target cells to which antibodies are bound are engulfed by phagocytic cells, such as macrophage, monocytes, neutrophils, and dendritic cells. Multiple Fc receptors are involved in this process.

[0195] A "blocking" antibody or an "antagonist" antibody is one which inhibits or reduces biological activity of the antigen it binds. Preferred blocking antibodies or antagonist antibodies substantially or completely inhibit the biological activity of the antigen.

[0196] An "agonist antibody", as used herein, is an antibody which mimics at least one of the functional activities of a polypeptide of interest.

[0197] As meant herein, an "Fc region" is a dimer consisting of two polypeptide chains joined by one or more disulfide bonds, each chain comprising part or all of a hinge domain plus a CH2 and a CH3 domain. Each of the polypeptide chains is referred to as an "Fc polypeptide chain." To distinguish the two Fe polypeptide chains, one is referred to herein as an "A chain" and the other is referred to as a "B chain." More specifically, the Fc regions contemplated for use with the present invention are IgG Fc regions, which can be mammalian or human lgG1 , lgG2, lgG3, or lgG4 Fc regions. Among human lgG1 Fc regions, at least two allelic types are known.

[0198] An "Fc-containing protein," as meant herein, is a protein comprising an Fc region as described herein and a binding region that binds to a target molecule. The term "Fc containing protein" encompasses an antibody or an Fc fusion protein that contains an Fc region.

[0199] The phrase “therapeutically effective amount” generally refers to an amount of an antigen binding protein of the present invention that (i) treats the particular disease, condition, or disorder, (ii) attenuates, ameliorates, or eliminates one or more symptoms of the particular disease, condition, or disorder, or (iii) delays the onset of one or more symptoms of the particular disease, condition, or disorder described herein.

[0200] The words “treat” or “treatment” refer to therapeutic treatment wherein the object is to slow down (lessen) an undesired physiological change or disorder. For purposes of this invention, beneficial or desired clinical results include, but are not limited to, alleviation of symptoms, diminishment of extent of disease, stabilized (i.e. , not worsening) state of disease, delay or slowing of disease progression, amelioration or palliation of the disease state, and remission (whether partial or total), whether detectable or undetectable. Treatment can also mean prolonging survival as compared to expected survival if not receiving treatment. Treatment may not necessarily result in the complete clearance of a disease or disorder but may reduce or minimise complications and side effects of infection and the progression of a disease or disorder. The success or otherwise of treatment may be monitored by, amongst other things, physical examination of the individual, cytopathological, serological DNA, or mRNA detection techniques.

[0201] The words “prevent” and “prevention” generally refer to prophylactic or preventative measures for protecting or precluding an individual not having a given disease or disorder from progressing to that disease or disorder.

[0202] The phrase “pharmaceutically acceptable” indicates that the substance or composition must be compatible chemically and / or toxicologically, with the other ingredients comprising a formulation, and / or the mammal being treated therewith.Mutations to Proteins

[0203] The present invention also provides an antigen binding protein or a nucleic acid encoding same having at least 80% identity to a sequence disclosed herein. In one example, an antigen binding protein or nucleic acid of the invention comprises sequence at least about 85% or 90% or 95% or 97% or 98% or 99% identical to a sequence disclosed herein.

[0204] Alternatively, or additionally, the antigen binding protein comprises a CDR (e.g., three CDRs) at least about 80% or 85% or 90% or 95% or 97% or 98% or 99% identical to CDR(s) of a VH or VL as described herein according to any example.

[0205] In another example, a nucleic acid of the invention comprises a sequence at least about 80% or 85% or 90% or 95% or 97% or 98% or 99% identical to a sequence encoding an antigen binding protein having a function as described herein according to any example. The present invention also encompasses nucleic acids encoding an antigen binding protein of the invention, which differs from a sequence exemplified herein as a result of degeneracy of the genetic code.

[0206] The % identity of a nucleic acid or polypeptide is determined by GAP (Needleman and Wunsch. Mol. Biol. 48, 443-453, 1970) analysis (GCG program) with a gap creation penalty=5, and a gap extension penalty=0.3. The query sequence is at least 50 residues in length, and the GAP analysis aligns the two sequences over a region of at least 50 residues. For example, the query sequence is at least 100 residues in length and the GAP analysis aligns the two sequences over a region of at least 100 residues. For example, the two sequences are aligned over their entire length.

[0207] The present invention also contemplates a nucleic acid that hybridizes under stringent hybridization conditions to a nucleic acid encoding an antigen binding protein described herein. A “moderate stringency” is defined herein as being a hybridization and / or washing carried out in 2 x SSC buffer, 0.1 % (w / v) SDS at a temperature in the range 45°C to 65°C, or equivalent conditions. A “high stringency” is defined herein as being a hybridization and / or wash carried out in 0.1 x SSC buffer, 0.1% (w / v) SDS, or lower salt concentration, and at a temperature of at least 65°C, or equivalent conditions. Reference herein to a particular level of stringency encompasses equivalent conditions using wash / hybridization solutions other than SSC known to those skilled in the art. For example, methods for calculating the temperature at which the strands of a double stranded nucleic acid will dissociate (also known as melting temperature, or Tm) are known in the art. A temperature that is similar to (e.g., within 5°C or within 10°C) or equal to the Tm of a nucleic acid is considered to be high stringency. Medium stringency is to be considered to be within 10°C to 20°C or 10°C to 15°C of the calculated Tm of the nucleic acid.

[0208] The present invention also contemplates mutant forms of an antigen binding protein of the invention comprising one or more conservative amino acid substitutions compared to a sequence set forth herein. In some examples, the antigen binding protein comprises 10 or fewer, e.g., 9 or 8 or 7 or 6 or 5 or 4 or 3 or 2 or 1 conservative amino acid substitutions. A “conservative amino acid substitution” is one in which the amino acid residue is replaced with an amino acid residue having a similar side chain and / or hydropathicity and / or hydrophilicity.

[0209] Families of amino acid residues having similar side chains have been defined in the art, including basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), p-branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). Hydropathic indices are described, for example in Kyte and Doolittle J. Mol. Biol., 157: 105-132, 1982 and hydrophylic indices are described in, e.g., US4554101.

[0210] The present invention also contemplates non-conservative amino acid changes. For example, of particular interest are substitutions of charged amino acids with another charged amino acid and with neutral or positively charged amino acids. In some examples, the antigen binding protein comprises 10 or fewer, e.g., 9 or 8 or 7 or 6 or 5 or 4 or 3 or 2 or 1 non-conservative amino acid substitutions.

[0211] In one example, the mutation(s) occur within a FR of an antigen binding domain of an antigen binding protein of the invention. In another example, the mutation(s) occur within a CDR of an antigen binding protein of the invention.

[0212] Exemplary methods for producing mutant forms of an antigen binding protein include:- mutagenesis of DNA (Thie et al., Methods Mol. Biol. 525: 309-322, 2009) or RNA (Kopsidas et al., Immunol. Lett. 107:163-168, 2006; Kopsidas et al. BMC Biotechnology, 7: 18, 2007; and W01999 / 058661);- introducing a nucleic acid encoding the polypeptide into a mutator cell, e.g., XL- 1 Red, XL-mutS and XL-mutS-Kanr bacterial cells (Stratagene);- DNA shuffling, e.g., as disclosed in Stemmer, Nature 370: 389-91 , 1994; and- site directed mutagenesis, e.g., as described in Dieffenbach (ed) and Dveksler (ed) (In: PCR Primer: A Laboratory Manual, Cold Spring Harbor Laboratories, NY, 1995).

[0213] Exemplary methods for determining biological activity of the mutant antigen binding proteins of the invention will be apparent to the skilled artisan and / or described herein, e.g., antigen binding. For example, methods for determining antigen binding, competitive inhibition of binding, affinity, association, dissociation and therapeutic efficacy are described herein.

[0214] As used herein, the properties of amino acids are defined in the following table:Constant Regions

[0215] The present invention encompasses antigen binding proteins and / or antibodies described herein comprising a constant region of an antibody. This includes antigen binding fragments of an antibody fused to an Fc.

[0216] Sequences of constant regions useful for producing the proteins of the present invention may be obtained from a number of different sources. In some examples, the constant region or portion thereof of the protein is derived from a human antibody. The constant region or portion thereof may be derived from any antibody class, including IgM, IgG, IgD, IgA and IgE, and any antibody isotype, including lgG1 , lgG2, lgG3 and lgG4. In one example, the constant region is human isotype lgG1 or a stabilized lgG1 constant region.

[0217] In various embodiments of the invention, the Fc region of the antibody may comprise one or more substitutions for altering effector function (including increasing or decreasing effector functions), and circulation half-life. Various examples of suchsubstitutions and modifications are described in Saunders (2019) Front. Immunol, article 1296, incorporated herein by reference in its entirety.

[0218] In one example, the Fc region of the constant region has a reduced ability to induce effector function, e.g., compared to a native or wild-type human lgG1 or lgG3 Fc region. In one example, the effector function is antibody-dependent cell-mediated cytotoxicity (ADCC) and / or antibody-dependent cell-mediated phagocytosis (ADCP) and / or complement-dependent cytotoxicity (CDC). Methods for assessing the level of effector function of an Fc region containing protein are known in the art and / or described herein.

[0219] In one example, the Fc region is an lgG4 Fc region (i.e. , from an lgG4 constant region), e.g., a human lgG4 Fc region. Sequences of suitable lgG4 Fc regions will be apparent to the skilled person and / or available in publically available databases (e.g., available from National Center for Biotechnology Information).

[0220] In one example, the constant region is a stabilized lgG4 constant region. The term “stabilized lgG4 constant region” will be understood to mean an lgG4 constant region that has been modified to reduce Fab arm exchange or the propensity to undergo Fab arm exchange or formation of a half-antibody or a propensity to form a half antibody. “Fab arm exchange" refers to a type of protein modification for human lgG4, in which an lgG4 heavy chain and attached light chain (half-molecule) is swapped for a heavy-light chain pair from another lgG4 molecule. Thus, lgG4 molecules may acquire two distinct Fab arms recognizing two distinct antigens (resulting in bispecific molecules). Fab arm exchange occurs naturally in vivo and can be induced in vitro by purified blood cells or reducing agents such as reduced glutathione. A “half antibody” forms when an lgG4 antibody dissociates to form two molecules each containing a single heavy chain and a single light chain.

[0221] In one example, a stabilized lgG4 constant region comprises a proline at position 241 of the hinge region according to the system of Kabat (Kabat et al., Sequences of Proteins of Immunological Interest Washington DC United States Department of Health and Human Services, 1987 and / or 1991). This position corresponds to position 228 of the hinge region according to the EU numbering system (Kabat et al., Sequences of Proteins of Immunological Interest Washington DC UnitedStates Department of Health and Human Services, 2001 and Edelman et al., Proc. Natl. Acad. USA, 63, 78-85, 1969). In human lgG4, this residue is generally a serine. Following substitution of the serine for proline, the lgG4 hinge region comprises a sequence CPPC (SEQ ID NO: 152). In this regard, the skilled person will be aware that the “hinge region” is a proline-rich portion of an antibody heavy chain constant region that links the Fc and Fab regions that confers mobility on the two Fab arms of an antibody. The hinge region includes cysteine residues which are involved in inter-heavy chain disulfide bonds. It is generally defined as stretching from Glu226 to Pro243 of human lgG1 according to the numbering system of Kabat. Hinge regions of other IgG isotypes may be aligned with the lgG1 sequence by placing the first and last cysteine residues forming inter-heavy chain disulphide (S-S) bonds in the same positions (see for example WO2010 / 080538).

[0222] Additional examples of stabilized lgG4 antibodies are antibodies in which arginine at position 409 in a heavy chain constant region of human lgG4 (according to the EU numbering system) is substituted with lysine, threonine, methionine, or leucine (e.g., as described in W02006 / 033386). The Fc region of the constant region may additionally or alternatively comprise a residue selected from the group consisting of: alanine, valine, glycine, isoleucine and leucine at the position corresponding to 405 (according to the EU numbering system). Optionally, the hinge region comprises a proline at position 241 (i.e. , a CPPC sequence, SEQ ID NO: 152) (as described above).

[0223] In another example, the Fc region is a region modified to have reduced effector function, i.e., a “non-immunostimulatory Fc region”. For example, the Fc region is an IgG 1 Fc region comprising a substitution at one or more positions selected from the group consisting of 268, 309, 330 and 331. In another example, the Fc region is an lgG1 Fc region comprising one or more of the following changes E233P, L234V, L235A and deletion of G236 and / or one or more of the following changes A327G, A330S and P331S (Armour et al., Eur J Immunol. 29:2613-2624, 1999; Shields et al., J Biol Chem. 276(9):6591-604, 2001). Additional examples of non-immunostimulatory Fc regions are described, for example, in Dall'Acqua et al., J Immunol. 177: 1129-1138 2006; and / or Hezareh J Virol ;75: 12161-12168, 2001).

[0224] Antibodies with reduced effector function include those with substitution of one or more of Fc region residues 238, 265, 269, 270, 297, 327 and 329 (as described in U.S. Patent No. 6,737,056, incorporated herein by reference). Such Fc mutants include Fc mutants with substitutions at two or more of amino acid positions 265, 269, 270, 297 and 327, including the so-called “DANA” Fc mutant with substitution of residues 265 and 297 to alanine (US Patent No. 7,332,581). For example, an antibody variant may comprise an Fc region with one or more amino acid substitutions which diminish FcyR binding, e.g., substitutions at positions 234 and 235 of the Fc region (EU numbering of residues). For example, the substitutions are L234A and L235A (LALA) (See, e.g., WO 2012 / 130831). The substitutions may additionally include substitution of the proline residue at position 329, such as a P329G mutation to disable binding to FcR (and thereby comprise a so- called “LALA-PG mutant Fc region”). Further, alterations may be made in the Fc region that result in altered (i.e., diminished) C1q binding and / or Complement Dependent Cytotoxicity (CDC), e.g., as described in US Patent No. 6,194,551 , WO 99 / 51642, and Idusogie et al. J. Immunol. 164: 4178-4184 (2000).

[0225] In some aspects, the Fc region includes mutations to the complement (C1q) and / or to Fc gamma receptor (FcyR) binding sites. In some aspects, such mutations can render the antibody incapable of antibody directed cytotoxicity (ADCC) and complement directed cytotoxicity (CDC). One example of a CDC-deficient antibody is one that comprises a substitution at one or more of Glu318, Lys320, Pro 329, Pro331 and Lys322 (for example, K322A), wherein the numbering of the residues in the Fc region is according to the EU index as described in Kabat et al.

[0226] In another example, the Fc region is a chimeric Fc region, e.g., comprising at least one CH2 domain from an lgG4 antibody and at least one CH3 domain from an I gG 1 antibody, wherein the Fc region comprises a substitution at one or more amino acid positions selected from the group consisting of 240, 262, 264, 266, 297, 299, 307, 309, 323, 399, 409 and 427 (EU numbering) (e.g., as described in WO2010 / 085682). Exemplary substitutions include 240F, 262L, 264T, 266F, 297Q, 299A, 299K, 307P, 309K, 309M, 309P, 323F, 399S, and 427F.Additional Modifications

[0227] The present invention also contemplates additional modifications to an antibody or antigen binding protein comprising an Fc region or constant region.

[0228] The neonatal Fc-receptor (FcRn) is important for the metabolic fate of antibodies of the IgG class in vivo. The FcRn functions to salvage IgG from the lysosomal degradation pathway, resulting in reduced clearance and increased half-life. FcRn binds with high affinity to the CH2-CH3 portion of the Fc-region of an antibody of the class IgG. The interaction between an antibody of the class IgG and the FcRn is pH dependent and occurs in a 1 :2 stoichiometry, i.e. one IgG antibody molecule can interact with two FcRn molecules via its two heavy chain Fc-region polypeptides (see e.g. Huber, A.H., et al, J. Mol. Biol. 230 (1993) 1077-1083).

[0229] In certain embodiments of the invention, an antibody may comprise one or more amino acid substitutions that increase the half-life of the protein. For example, the antibody comprises a Fc region comprising one or more amino acid substitutions that increase the affinity of the Fc region for the neonatal Fc region (FcRn). For example, the Fc region has increased affinity for FcRn at lower pH, e.g., about pH 6.0, to facilitate Fc / FcRn binding in an endosome. In one example, the Fc region has increased affinity for FcRn at about pH 6 compared to its affinity at about pH 7.4, which facilitates the re- release of Fc into blood following cellular recycling. These amino acid substitutions are useful for extending the half-life of a protein, by reducing clearance from the blood.

[0230] Exemplary amino acid substitutions include T250Q and / or M428L or T252A, T254S and T266F or M252Y, S254T and T256E or H433K and N434F according to the Ell numbering system. Additional or alternative amino acid substitutions are described, for example, in US20070135620 or US7083784.

[0231] In further embodiments, the antibody comprises one or more amino acid substitutions that decrease the half-life of the protein. For example, the antibody comprises a Fc region comprising one or more amino acid substitutions that decrease or reduce the affinity of the Fc region for the neonatal Fc region (FcRn).

[0232] The present invention therefore provides for an antibody having substitutions in the CH2 and / or CH3 domains of the constant region and comprising substitutions at one or more of residues His310, His435, His436 and Ile253 (Kabat numbering), therebyaltering FcRn binding affinity and / or serum half-life of said antibody relative to a naturally occurring antibody.

[0233] In some examples, the amino acid at position 310 and / or 435 of the antibody may be alanine, glutamic acid, aspartic acid, leucine, isoleucine, arginine, proline, glutamine, methionine, serine, threonine, lysine, asparagine, phenylalanine, tyrosine, tryptophan, cysteine, valine or glycine.

[0234] Preferably, the residue at position 310 is selected from alanine, or glutamic acid or glutamine; or amino acid residue 435 from the heavy chain constant region is selected from arginine, glutamine or alanine. In other preferred embodiments, the antibody has an alanine residue at position 310 and glutamine residue at position 435.

[0235] In a preferred embodiment of the present invention, the binding affinity for FcRn and / or the serum half-life of the modified antibody is decreased by at least about 2-fold, 3-fold, 4-fold, 5-fold, 10-fold, 15-fold, 20-fold, 25-fold, 30-fold, 40-fold, 50-fold, 60-fold, 70- fold, 80-fold, 90-fold, or 100-fold. In a preferred embodiment of the present invention, the binding affinity for FcRn and / or the serum half-life of said modified antibody is reduced by at least about 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 97%, 98%, or 99%.

[0236] The antibody may also comprise amino acid substitutions at residues equivalent to Ser228 and Leu235 of the constant heavy chain region, such as Ser228Pro amd / or Leu235Glu.Antibody Binding Domain Containing Proteins

[0237] In another embodiment there is provided an antigen binding protein as described above wherein an amino acid sequence forming one or more of FR1 , CDR1 , FR2, CDR2, FR3, CDR3 and FR4 is derived from a human sequence or in the form of a human sequence.

[0238] The antigen binding protein may be presented in a humanized form including non-human (e.g., murine) and human immunoglobulin sequences. Typically all but the CDR sequences of the antigen binding protein are from a non-human species such as mouse, rat or rabbit. In some instances, framework residues of the antigen binding proteinmay also be non-human. Where the antigen binding protein is provided in the form of a whole antibody, typically at least a portion of an immunoglobulin constant region (Fc) is human, thereby allowing various human effector functions.

[0239] Methods for humanizing non-human antigen binding proteins are well known in the art, examples of suitable processes including those in Jones et al., (1986) Nature, 321 :522; Riechmann et al., (1988) Nature, 332:323; Verhoeyen et al., (1988) Science, 239:1534.

[0240] Variable domains including CDRs and FRs of the invention may have been made less immunogenic by replacing surface-exposed residues so as to make the antibody appear as self to the immune system. Padlan, E. A., 1991 , Mol. Immunol. 28, 489 provides an exemplary method. Generally, affinity is preserved because the internal packing of amino acid residues in the vicinity of the antigen binding protein remains unchanged and generally CDR residues or adjacent residues which influence binding characteristics are not to be substituted in these processes.

[0241] In another embodiment there is provided an anti-CD80 binding protein, immunoglobulin variable domain, antibody, dab, scFv, Fab, Fab', F(ab')2, Fv fragment, diabody, triabody, linear antibody, single-chain antibody molecule, or multispecific antibody as described herein, preferably with a sequence as shown in the tables herein.

[0242] In certain embodiments, the antigen binding protein is provided in the form of a single chain Fv fragment (scFv). Fv and scFv are suitable for reduced nonspecific binding during in vivo use as they have intact combining sites that are devoid of constant regions. Fusion proteins including scFv may be constructed to yield fusion of an effector protein at either the amino or the carboxy terminus of an scFv.

[0243] In another embodiment there is provided a diabody or triabody or other multispecific antibody including an antigen binding protein as described above. Multispecific antibodies may be assembled using polypeptide domains that allow for multimerization. Examples include the CH2 and CH3 regions of the Fc and the CH1 and Ckappa / lambda regions. Other naturally occurring protein multimerization domains may be used including leucine zipper domain (bZIP), helix-loop-helix motif, Src homologydomain (SH2, SH3), an EF hand, a phosphotyrosine binding (PTB) domain, or other domains known in the art.

[0244] In another embodiment there is provided a fusion domain or heterologous protein including an antigen binding protein, immunoglobulin variable domain, antibody, dab, scFv, Fab, Fab', F(ab')2, Fv fragment, diabody, triabody, linear antibody, singlechain antibody molecule, or multispecific antibody as described herein.

[0245] A heterologous polypeptide may be recombinantly fused or chemically conjugated to an N- or C- terminus of an antigen binding protein or molecule containing same of the invention.

[0246] Further, the antigen binding protein, immunoglobulin variable domain, antibody, dab, scFv, Fab, Fab', F(ab')2, Fv fragment, diabody, triabody, linear antibody, singlechain antibody molecule, or multispecific antibody of the invention may be modified by glycosylation, acetylation, pegylation, phosphorylation, amidation, derivatization by known protecting / blocking groups, proteolytic cleavage, linkage to a cellular ligand or other protein, etc.Further details of antigen binding proteins of the invention

[0247] Antigen binding proteins of the invention can be composed of amino acids joined to each other by peptide bonds or modified peptide bonds, i.e., peptide isosteres, and may contain amino acids other than the 20 gene-encoded amino acids. Antigen binding proteins of the invention may be modified by natural processes, such as posttranslational processing, or by chemical modification techniques which are well known in the art. Such modifications are well described in basic texts, as well as in research literature. Modifications can occur anywhere in the antigen binding protein, including the peptide backbone, the amino acid side-chains and the amino or carboxyl termini, or on moieties such as carbohydrates. It will be appreciated that the same type of modification may be present in the same or varying degrees at several proteins in a given antigen binding protein. Also, a given antigen binding protein may contain many types of modifications. An antigen binding protein may be branched, for example, as a result of ubiquitination, and they may be cyclic, with or without branching. Cyclic, branched, and branched cyclic antigen binding proteins may result from post-translation natural processes or may bemade by synthetic methods. Modifications include acetylation, acylation, ADP- ribosylation, amidation, covalent attachment of flavin, covalent attachment of a heme moiety, covalent attachment of a nucleotide or nucleotide derivative, covalent attachment of a lipid or lipid derivative, covalent attachment of phosphotidylinositol, cross-linking, cyclization, disulfide bond formation, demethylation, formation of covalent cross-links, formation of cysteine, formation of pyroglutamate, formylation, gamma-carboxylation, glycosylation, GPI anchor formation, hydroxylation, iodination, methylation, myristoylation, oxidation, pegylation, proteolytic processing, phosphorylation, prenylation, racemization, selenoylation, sulfation, transfer-RNA mediated addition of amino acids to proteins such as arginylation, and ubiquitination.

[0248] In another embodiment there is provided a conjugate in the form of an antigen binding protein, immunoglobulin variable domain, antibody, Fab, dab, scFv, diabody, triabody or fusion protein as described above conjugated to a cytotoxic agent such as a chemo therapeutic agent, a drug, a growth inhibitory agent, a toxin (e.g., an enzymatically active toxin of bacterial, fungal, plant, or animal origin, or fragments thereof), or a label such as a radioactive isotope (i.e., a radio conjugate). In another aspect, the invention further provides methods of using the immunoconjugates. In one aspect, an immunoconjugate comprises any of the above variable domains covalently attached to a cytotoxic agent or a detectable agent.

[0249] In another embodiment there is provided an antibody for binding to an antigen binding protein, immunoglobulin variable domain, antibody, dab, scFv, Fab, Fab', F(ab')2, Fv fragment, diabody, triabody, linear antibody, single-chain antibody molecule, or multispecific antibody, fusion protein or conjugate as described above.

[0250] In another embodiment there is provided a nucleic acid encoding an antigen binding protein, immunoglobulin variable domain, antibody, dab, scFv, Fab, Fab', F(ab')2, Fv fragment, diabody, triabody, linear antibody, single-chain antibody molecule, or multispecific antibody, fusion protein or conjugate as described above.

[0251] A polynucleotide encoding an CDR or FR according to any one of the general formulae described above, or an antigen binding protein comprised of same, may be generated from a nucleic acid from any source, for example by chemical synthesis or isolation from a cDNA or genomic library. For example a cDNA library may be generatedfrom an antibody producing cell such as a B cell, plasma cell or hybridoma cell and the relevant nucleic acid isolated by PCR amplification using oligonucleotides directed to the particular clone of interest. Isolated nucleic acids may then be cloned into vectors using any method known in the art. The relevant nucleotide sequence may then be mutagenized using methods known in the art e.g., recombinant DNA techniques, site directed mutagenesis, PCR, etc. (see, for example, the techniques described in Sambrook et al., 1990, Molecular Cloning, A Laboratory Manual, 2d Ed., Cold Spring Harbor Laboratory, Cold Spring Harbor, N. Y. and Ausubel et al., eds., 1998, Current Protocols in Molecular Biology, John Wiley & Sons, NY), to generate antigen binding proteins having a different amino acid sequence, for example to create amino acid substitutions, deletions, and / or insertions.Linkers

[0252] In any embodiment, VH and VL regions of antigen binding domains as described herein may be linked together via a linker. Further, antigen binding fragments of antibodies (such as scFvs) and variants thereof, may be linked to Fc regions via a linker. The following section describes linkers which may be used for joining any polypeptides described herein.

[0253] The term “linker” is used to denote polypeptides comprising two or more amino acid residues joined by peptide bonds and are used to link one or more antigen binding portions. Such linker polypeptides are well known in the art (see e.g., Holliger, P., et al. (1993) Proc. Natl. Acad. Sci. USA 90:6444-6448; Poljak, R. J., et al. (1994) Structure 2:1121-1123). A variety of linkers may find use in some embodiments described herein to covalently link Fc regions to a fusion partner.

[0254] “Linker” herein is also referred to as “linker sequence”, “spacer”, “tethering sequence” or grammatical equivalents thereof. Homo-or hetero-bifunctional linkers as are well known (see, 1994 Pierce Chemical Company catalog, technical section on crosslinkers, pages 155-200, incorporated entirely by reference). A number of strategies may be used to covalently link molecules together. These include, but are not limited to polypeptide linkages between N- and C-termini of proteins or protein domains, linkage via disulfide bonds, and linkage via chemical cross-linking reagents. In one aspect of this embodiment, the linker is a peptide bond, generated by recombinant techniques orpeptide synthesis. The linker peptide may predominantly include the following amino acid residues: Gly, Ser, Ala, or Thr. The linker peptide should have a length that is adequate to link two molecules in such a way that they assume the correct conformation relative to one another so that they retain the desired activity. In one embodiment, the linker is from about 1 to 50 amino acids in length, preferably about 1 to 30 amino acids in length. In one embodiment, linkers of 1 to 20 amino acids in length may be used. Useful linkers include glycine-serine polymers, including for example (GS)n, (GSGGS)n (SEQ ID NO: 153), (GGGGS)n (SEQ ID NO: 154), and (GGGS)n (SEQ ID NO: 155), where n is an integer of at least one, glycine-alanine polymers, alanine-serine polymers, and other flexible linkers. Alternatively, a variety of nonproteinaceous polymers, including but not limited to polyethylene glycol (PEG), polypropylene glycol, polyoxyalkylenes, or copolymers of polyethylene glycol and polypropylene glycol, may find use as linkers, that is may find use as linkers The fusion proteins of the invention may comprise a linker region (or spacer) located between the first and second portions.

[0255] A linker is usually a peptide having a length of up to 20 amino acids. The term “linked to” or “fused to” refers to a covalent bond, e.g., a peptide bond, formed between two moieties. Accordingly, in the context of the present invention the linker may have a length of 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 or 22 amino acids.

[0256] The linker may be a flexible linker (such as those comprising repeats of glycine and serine residues), a rigid linker (such as those comprising glutamic acid and lysine residues, flanking alanine repeats) and / or a cleavable linker (such as sequences that are susceptible by protease cleavage). Examples of such linkers are known to the skilled person and are described for example, in Chen et al., (2013) Advanced Drug Delivery Reviews, 65: 1357-1369.

[0257] In some aspects, the peptide linker may include the amino acids glycine and serine in various lengths and combinations. In some aspects, the peptide linker can include the sequence Gly-Gly-Ser (GGS), Gly-Gly-Gly-Ser (GGGS, SEQ ID NO: 155) or Gly-Gly-Gly-Gly-Ser (GGGGS, SEQ ID NO: 154) and variations or repeats thereof. In some aspects, the peptide linker can include the amino acid sequence GGGGGS (a linker of 6 amino acids in length, SEQ ID NO: 156) or even longer. The linker may a series ofrepeating glycine and serine residues (GS) of different lengths, i.e. , (GS)n where n is any number from 1 to 15 or more. For example, the linker may be (GS)3(i.e., GSGSGS, SEQ ID NO: 157) or longer (GS)n (SEQ ID NO: 158) or longer. It will be appreciated that n can be any number including 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or more. Fusion proteins having linkers of such length are included within the scope of the present invention. Similarly, the linker may be a series of repeating glycine residues separated by serine residues. For example (GGGGS)3 (i.e., the linker may comprise the amino acid sequence GGGGSGGGGSGGGGS, (G4S)3, SEQ ID NO: 159), and variations thereof.

[0258] The peptide linker may consist of a series of repeats of Thr-Pro (TP) comprising one or more additional amino acids N and C terminal to the repeat sequence. For example, the linker may comprise or consist of the sequence GTPTPTPTPTGEF (SEQ ID NO: 160) (also known as the TP5 linker). In further aspects, the linker may be a short and / or alpha-helical rigid linker (e.g. A(EAAAK)3A, SEQ ID NO: 161 ; PAPAP, SEQ ID NO: 162; or a dipeptide such as LE).

[0259] In certain aspects, the linker may be flexible and cleavable. Such linkers preferably comprise one or more recognition sites for a protease to enable cleavage.

[0260] Preferred linkers may comprise sequences from an antibody hinge region. Hinge regions sequences from any antibody isotype may be used, including for example hinge sequences from I gG 1 , 1 gG2, 1 gG3, and / or lgG4. Linker sequences may also include any sequence of any length of CL / CH1 domain but not all residues of CL / CH1 domain; for example, the first 5-12 amino acid residues of the CL / CH1 domains. Linkers can be derived from immunoglobulin heavy chains of any isotype, including for example Cy1 , Cy2, Cy3, Cy4, CcH , Ca2, Cb, CE, and Cp. Linkers can be derived from immunoglobulin light chain, for example CK or CA. Linker sequences may also be derived from other proteins such as Ig-like proteins (e.g. TCR, FcR, KIR), hinge region-derived sequences, and other natural sequences from other proteins.Protein Production

[0261] In another embodiment there is provided a method for producing an anti-CD80 antigen binding protein as described above including expressing a nucleic acid as described above in a cell or non-human animal as described above.

[0262] The production of an antigen binding protein of the invention generally requires an expression vector containing a polynucleotide that encodes the antigen binding protein of the invention. A polynucleotide encoding an antigen binding protein of the invention may be obtained and sub cloned into a vector for the production of an antigen binding protein by recombinant DNA technology using techniques well-known in the art, including techniques described herein. Many different expression systems are contemplated including the use of mammalian cells including human cells for production and secretion of antigen binding proteins. Examples of cells include 293F, CHO and the NSO cell line.

[0263] Expression vectors containing protein coding sequences and appropriate transcriptional and translational control signals can be constructed using methods known in the art. These include in vitro recombinant DNA techniques, synthetic techniques and in vivo genetic recombination. In certain embodiments there is provided a replicable vector having a nucleic acid encoding an antigen binding protein operably linked to a promoter.

[0264] Cells transfected with an expression vector may be cultured by conventional techniques to produce an antigen binding protein. Thus, in certain embodiments, there is provided host cells or cell transfectants containing a polynucleotide encoding an antigen binding protein of the invention operably linked to a promoter. The promoter may be heterologous. A variety of host-expression vector systems may be utilized and in certain systems the transcription machinery of the vector system is particularly matched to the host cell. For example, mammalian cells such as Chinese hamster ovary cells (CHO) may be transfected with a vector including the major intermediate early gene promoter element from human cytomegalovirus. Additionally or alternatively, a host cell may be used that modulates the expression of inserted sequences, or modifies and processes the gene product as required, including various forms of post translational modification. Examples of mammalian host cells having particular post translation modification processes include CHO, VERY, BHK, Hela, COS, MDCK, 293, 3T3, W138, BT483, Hs578T, HTB2, BT2O and T47D, NSO, CRL7O3O and HsS78Bst cells.

[0265] Depending upon the use intended for the protein molecule, a number of bacterial expression vectors may be advantageously selected. In one example, vectors that cause the expression of high levels of fusion protein products that are readily purified,such as the E. coli expression vector pUR278 may be used where a large quantity of an antigen binding protein is to be produced. The expression product may be produced in the form of a fusion protein with lacZ. Other bacterial vectors include pIN vectors and the like. pGEX vectors may also be used to express foreign polypeptides as fusion proteins with glutathione-S-transferase (GST). These fusion proteins are generally soluble and can easily be purified from lysed cells by adsorption and binding to glutathione-agarose affinity matrix followed by elution in the presence of free glutathione. A thrombin and / or factor Xa protease cleavage site may be provided in the expressed polypeptide so that the cloned target gene product can be released from the GST moiety.

[0266] Autographa californica nuclear polyhedrosis virus (AcNPV) may be used as a vector to express foreign genes in an insect system including Spodoptera frugiperda cells. The particular promoter used may depend on where the protein coding is inserted into the sequence. For example, the sequence may be cloned individually into the polyhedrin gene and placed under control of the polyhedrin promoter.

[0267] Virus based expression systems may be utilized with mammalian cells such as an adenovirus whereby the coding sequence of interest may be ligated to the adenoviral late promoter and tripartite leader sequence. In vitro or in vivo recombination may then be used to insert this chimeric gene into the adenoviral genome. Insertions into region E1 or E3 will result in a viable recombinant virus that is capable of expressing the antigen binding protein in infected host cells. Specific initiation signals including the ATG initiation codon and adjacent sequences may be required for efficient translation of inserted antigen binding protein coding sequences. Initiation and translational control signals and codons can be obtained from a variety of origins, both natural and synthetic. Transcription enhancer elements and transcription terminators may be used to enhance the efficiency of expression of a viral based system.

[0268] Where long-term, high-yield production of recombinant proteins is required, stable expression is preferred. Generally a selectable marker gene is used whereby following transfection, cells are grown for 1-2 days in an enriched media and then transferred to a medium containing a selective medium in which cells containing the corresponding selectable marker, for example, antibiotic resistance can be screened. The result is that cells that have stably integrated the plasmid into their chromosomes growand form foci that in turn can be cloned and expanded into cell lines. The herpes simplex virus thymidine kinase, hypoxanthineguanine phosphoribosyltransferase and adenine phosphoribosyltransferase genes are examples of genes that can be employed in tk-, hgprt- or aprT- cells, respectively, thereby providing appropriate selection systems. The following genes: dhfr, which confers resistance to methotrexate; gpt, which confers resistance to mycophenolic acid; neo, which confers resistance to the aminoglycoside G- 418; and hygro, which confers resistance to hygromycin are examples of genes that can be used in anti-metabolite selection systems.

[0269] An antigen binding protein of the invention may be purified by a recombinant expression system by known methods including ion exchange chromatography, affinity chromatography (especially affinity for the specific antigens Protein A or Protein G) and gel filtration column chromatography), centrifugation, differential solubility, or by any other standard technique for the purification of proteins. Purification may be facilitated or assisted by providing the antigen binding protein in the form of a fusion protein.

[0270] Large quantities of the antigen binding proteins of the invention may be produced by a scalable process starting with a pilot expression system in a research laboratory that is scaled up to an analytical scale bioreactor (typically from 5L to about 50L bioreactors) or production scale bioreactors (for example, but not limited to 75L, 100L, 150L, 300L, or 500L). Desirable scalable processes include those wherein there are low to undetectable levels of aggregation as measured by HPSEC or rCGE, typically no more than 5% aggregation by weight of protein down to no more than 0.5% by weight aggregation of protein. Additionally or alternatively, undetectable levels of fragmentation measured in terms of the total peak area representing the intact antigen binding protein may be desired in a scalable process so that at least 80% and as much as 99.5% or higher of the total peak area represents intact antigen binding protein. In other embodiments, the scalable process of the invention produces antigen binding proteins at production efficiency of about from 10 mg / L to about 300 mg / L or higher.

[0271] Various techniques have been developed for the production of antibody fragments including proteolytic digestion of intact antibodies and recombinant expression in host cells. With regard to the latter, as described below, Fab, Fv and scFv antibody fragments can all be expressed in and secreted from E. coli, antibody fragments can beisolated from the antibody phage libraries and Fab'-SH fragments can be directly recovered from E. coli and chemically coupled to form F(ab')2 fragments. In another approach, F(ab')2 fragments are isolated directly from recombinant host cell culture.

[0272] In another embodiment there is provided a vector including a nucleic acid described above. The vector may, for example, be in the form of a plasmid, cosmid, viral particle, or phage. The appropriate nucleic acid sequence may be inserted into the vector by a variety of procedures. In general, DNA is inserted into an appropriate restriction endonuclease site(s) using techniques known in the art. Vector components generally include, but are not limited to, one or more of a signal sequence, an origin of replication, one or more marker genes, an enhancer element, a promoter, and a transcription termination sequence. Construction of suitable vectors containing one or more of these components employs standard ligation techniques which are known to the skilled artisan.

[0273] The antigen binding site may be produced recombinantly not only directly, but also as a fusion polypeptide with a heterologous polypeptide, which may be a signal sequence or other polypeptide having a specific cleavage site at the N-terminus of the mature protein or polypeptide. In general, the signal sequence may be a component of the vector, or it may be a part of the antigen binding site-encoding DNA that is inserted into the vector. The signal sequence may be a prokaryotic signal sequence selected, for example, from the group of the alkaline phosphatase, penicillinase, Ipp, or heat-stable enterotoxin II leaders. For yeast secretion the signal sequence may be, e.g., the yeast invertase leader, alpha factor leader, or acid phosphatase leader or the C. albicans glucoamylase leader. In mammalian cell expression, mammalian signal sequences may be used to direct secretion of the protein, such as signal sequences from secreted polypeptides of the same or related species, as well as viral secretory leaders.

[0274] Polynucleotide sequences encoding polypeptide components of the antigen binding protein of the invention can be obtained using standard recombinant techniques as described above. Polynucleotides can be synthesized using nucleotide synthesizer or PCR techniques. Once obtained, sequences encoding the polypeptides are inserted into a recombinant vector capable of replicating and expressing heterologous polynucleotides in prokaryotic hosts. Many vectors that are available and known in the art can be used for the purpose of the present invention. Selection of an appropriate vector will dependmainly on the size of the nucleic acids to be inserted into the vector and the particular host cell to be transformed with the vector. Each vector contains various components, depending on its function (amplification or expression of heterologous polynucleotide, or both) and its compatibility with the particular host cell in which it resides.

[0275] In general, plasmid vectors containing replicon and control sequences which are derived from species compatible with the host cell are used in connection with these hosts. Both expression and cloning vectors contain a nucleic acid sequence that enables the vector to replicate in one or more selected host cells, as well as marking sequences which are capable of providing phenotypic selection in transformed cells. Such sequences are well known for a variety of bacteria, yeast, and viruses. The origin of replication from the plasmid pBR322, which contains genes encoding ampicillin (Amp) and tetracycline (Tet) resistance and thus provides easy means for identifying transformed cells, is suitable for most Gram-negative bacteria, the 2pm plasmid origin is suitable for yeast, and various viral origins (SV40, polyoma, adenovirus, VSV or BPV) are useful for cloning vectors in mammalian cells. pBR322, its derivatives, or other microbial plasmids or bacteriophage may also contain, or be modified to contain, promoters which can be used by the microbial organism for expression of endogenous proteins.

[0276] In addition, phage vectors containing replicon and control sequences that are compatible with the host microorganism can be used as transforming vectors in connection with these hosts. For example, bacteriophage such as AGEM.TM.-11 may be utilized in making a recombinant vector which can be used to transform susceptible host cells such as E. coli LE392.

[0277] The expression vector of the invention may comprise two or more promoter- cistron (a cistron being segment of DNA that contains all the information for production of single polypeptide) pairs. A promoter is an untranslated regulatory sequence located upstream (5') to a cistron that modulates its expression. Prokaryotic promoters typically fall into two classes, inducible and constitutive. Inducible promoter is a promoter that initiates increased levels of transcription of the cistron under its control in response to changes in the culture condition, e.g. the presence or absence of a nutrient or a change in temperature.

[0278] A large number of promoters recognized by a variety of potential host cells are well known. The selected promoter can be operably linked to cistron DNA encoding the light or heavy chain by removing the promoter from the source DNA via restriction enzyme digestion and inserting the isolated promoter sequence into the vector of the invention. Both the native promoter sequence and many heterologous promoters may be used to direct amplification and / or expression of the target genes. In some embodiments, heterologous promoters are utilized, as they generally permit greater transcription and higher yields of expressed target gene as compared to the native target polypeptide promoter.

[0279] Promoters recognized by a variety of potential host cells are well known. Promoters suitable for use with prokaryotic hosts include the PhoA promoter, the p- galactamase and lactose promoter systems, alkaline phosphatase, a tryptophan (trp) promoter system and hybrid promoters such as the tac or the trc promoter. Promoters for use in bacterial systems also will contain a Shine-Dalgarno (S.D.) sequence operably linked to the DNA encoding an antigen binding protein of the invention. However, other promoters that are functional in bacteria (such as other known bacterial or phage promoters) are suitable as well. Their nucleotide sequences have been published, thereby enabling a skilled person operably to ligate them to cistrons encoding the target light and heavy chains using linkers or adaptors to supply any required restriction sites.

[0280] In one aspect of the invention, each cistron within the recombinant vector comprises a secretion signal sequence component that directs translocation of the expressed polypeptides across a membrane. In general, the signal sequence may be a component of the vector, or it may be a part of the target polypeptide DNA that is inserted into the vector. The signal sequence selected for the purpose of this invention should be one that is recognized and processed (i.e. cleaved by a signal peptidase) by the host cell. For prokaryotic host cells that do not recognize and process the signal sequences native to the heterologous polypeptides, the signal sequence is substituted by a prokaryotic signal sequence selected, for example, from the group consisting of the alkaline phosphatase, penicillinase, Ipp, or heat-stable enterotoxin II (STII) leaders, LamB, PhoE, PelB, OmpA and MBP. In one embodiment of the invention, the signal sequences used in both cistrons of the expression system are STII signal sequences or variants thereof.

[0281] In another aspect, the production of the immunoglobulins according to the invention can occur in the cytoplasm of the host cell, and therefore does not require the presence of secretion signal sequences within each cistron. In that regard, immunoglobulin light and heavy chains are expressed, folded and assembled to form functional immunoglobulins within the cytoplasm. Certain host strains (e.g., the E. coli trxB strains) provide cytoplasm conditions that are favourable for disulfide bond formation, thereby permitting proper folding and assembly of expressed protein subunits.

[0282] The present invention provides an expression system in which the quantitative ratio of expressed polypeptide components can be modulated in order to maximize the yield of secreted and properly assembled antigen binding proteins of the invention. Such modulation is accomplished at least in part by simultaneously modulating translational strengths for the polypeptide components.

[0283] In terms of expression in eukaryotic host cells, the vector components generally include, but are not limited to, one or more of the following: a signal sequence, an origin of replication, one or more marker genes, an enhancer element, a promoter, and a transcription termination sequence.

[0284] A vector for use in a eukaryotic host cell may also contain a signal sequence or other polypeptide having a specific cleavage site at the N-terminus of the mature protein or polypeptide of interest. The heterologous signal sequence selected preferably is one that is recognized and processed {i.e., cleaved by a signal peptidase) by the host cell. In mammalian cell expression, mammalian signal sequences as well as viral secretory leaders, for example, the herpes simplex gD signal, are available.

[0285] The DNA for such precursor region is ligated in reading frame to DNA encoding the antibody.

[0286] Generally, an origin of replication component is not needed for mammalian expression vectors. For example, the SV40 origin may typically be used only because it contains the early promoter.

[0287] Expression and cloning vectors will typically contain a selection gene, also termed a selectable marker. Typical selection genes encode proteins that (a) confer resistance to antibiotics or other toxins, e.g., ampicillin, neomycin, methotrexate, ortetracycline, (b) complement auxotrophic deficiencies, or (c) supply critical nutrients not available from complex media, e.g., the gene encoding D-alanine racemase for Bacilli.

[0288] One example of a selection scheme utilizes a drug to arrest growth of a host cell. Those cells that are successfully transformed with a heterologous gene produce a protein conferring drug resistance and thus survive the selection regimen. Examples of such dominant selection use the drugs neomycin, mycophenolic acid and hygromycin.

[0289] An example of suitable selectable markers for mammalian cells are those that enable the identification of cells competent to take up the antigen binding proteinencoding nucleic acid, such as DHFR or thymidine kinase, metallothionein-l and -II, preferably primate metallothionein genes, adenosine deaminase, ornithine decarboxylase, etc. An appropriate host cell when wild-type DHFR is employed is the CHO cell line deficient in DHFR activity (e.g., ATCC CRL-9096), prepared and propagated. For example, cells transformed with the DHFR selection gene are first identified by culturing all of the transformants in a culture medium that contains methotrexate (Mtx), a competitive antagonist of DHFR. Alternatively, host cells (particularly wild-type hosts that contain endogenous DHFR) transformed or cotransformed with DNA sequences encoding an antibody, wild-type DHFR protein, and another selectable marker such as aminoglycoside 3 '-phosphotransferase (APH) can be selected by cell growth in medium containing a selection agent for the selectable marker such as an aminoglycosidic antibiotic, e.g., kanamycin, neomycin, or G418.

[0290] Expression and cloning vectors usually contain a promoter operably linked to the antigen binding protein encoding nucleic acid sequence to direct mRNA synthesis. Promoters recognized by a variety of potential host cells are well known.

[0291] Eukaryotic genes generally have an AT-rich region located approximately 25 to 30 bases upstream from the site where transcription is initiated. Another sequence found 70 to 80 bases upstream from the start of transcription of many genes is a CNCAAT region where N may be any nucleotide. At the 3' end of most eukaryotic genes is an AATAAA sequence that may be the signal for addition of the poly A tail to the 3' end of the coding sequence. All of these sequences are suitably inserted into eukaryotic expression vectors.

[0292] Examples of suitable promoting sequences for use with yeast hosts include the promoters for 3- phosphoglycerate kinase or other glycolytic enzymes including enolase, glyceraldehyde-3- phosphate dehydrogenase, hexokinase, pyruvate decarboxylase, phosphofructokinase, glucose-6-phosphate isomerase, 3 -phosphoglycerate mutase, pyruvate kinase, triosephosphate isomerase, phosphoglucose isomerase, and glucokinase.

[0293] Other yeast promoters, which are inducible promoters having the additional advantage of transcription controlled by growth conditions, are the promoter regions for alcohol dehydrogenase 2, isocytochrome C, acid phosphatase, degradative enzymes associated with nitrogen metabolism, metallothionein, glyceraldehyde-3- phosphate dehydrogenase, and enzymes responsible for maltose and galactose utilization.

[0294] Antigen binding protein transcription from vectors in mammalian host cells is controlled, for example, by promoters obtained from the genomes of viruses such as polyoma virus, fowlpox virus, adenovirus (such as Adenovirus 2), bovine papilloma virus, avian sarcoma virus, cytomegalovirus, a retrovirus, hepatitis-B virus and Simian Virus 40 (SV40), from heterologous mammalian promoters, e.g., the actin promoter or an immunoglobulin promoter, and from heat-shock promoters, provided such promoters are compatible with the host cell systems.

[0295] Transcription of a DNA encoding the antigen binding protein by higher eukaryotes may be increased by inserting an enhancer sequence into the vector. Enhancer sequences include those known from mammalian genes (globin, elastase, albumin, a-fetoprotein, and insulin). Typically, however, one will use an enhancer from a eukaryotic cell virus. Examples include the SV40 enhancer on the late side of the replication origin (bp 100-270), the cytomegalovirus early promoter enhancer, the polyoma enhancer on the late side of the replication origin, and adenovirus enhancers.

[0296] Expression vectors used in eukaryotic host cells (yeast, fungi, insect, plant, animal, human, or nucleated cells from other multicellular organisms) will also contain sequences necessary for the termination of transcription and for stabilizing the mRNA. Such sequences are commonly available from the 5' and, occasionally 3', untranslated regions of eukaryotic or viral DNAs or cDNAs. These regions contain nucleotide segmentstranscribed as polyadenylated fragments in the untranslated portion of the mRNA encoding an antigen binding protein.

[0297] In another embodiment there is provided a cell including a vector or nucleic acid described above. The nucleic acid molecule or vector may be present in the genetically modified host cell or host either as an independent molecule outside the genome, preferably as a molecule which is capable of replication, or it may be stably integrated into the genome of the host cell or host.

[0298] The host cell of the present invention may be any prokaryotic or eukaryotic cell.

[0299] Examples of prokaryotic cells are those generally used for cloning like E. coli or Bacillus subtilis. Furthermore, eukaryotic cells comprise, for example, fungal or animal cells.

[0300] Examples for suitable fungal cells are yeast cells, preferably those of the genus Saccharomyces and most preferably those of the species Saccharomyces cerevisiae.

[0301] Examples of animal cells are, for instance, insect cells, vertebrate cells, preferably mammalian cells, such as e.g. HEK293, NSO, CHO, MDCK, LI2-OS, Hela, NIH3T3, MOLT-4, Jurkat, PC-12, PC-3, IMR, NT2N, Sk-n-sh, CaSki, C33A. These host cells, e.g. CHO-cells, may provide post- translational modifications to the antibody molecules of the invention, including leader peptide removal, folding and assembly of H (heavy) and L (light) chains, glycosylation of the molecule at correct sides and secretion of the functional molecule.

[0302] Further suitable cell lines known in the art are obtainable from cell line depositories, like the American Type Culture Collection (ATCC).

[0303] In another embodiment there is provided an animal including a cell described above. In certain embodiments, animals and tissues thereof containing a transgene are useful in producing the antigen binding proteins of the invention. The introduction of the nucleic acid molecules as transgenes into non-human hosts and their subsequent expression may be employed for the production of the antigen binding proteins, for example, the expression of such a transgene in the milk of the transgenic animal provide for means of obtaining the antigen binding proteins in quantitative amounts. Usefultransgenes in this respect comprise the nucleic acid molecules of the invention, for example, coding sequences for the antigen binding proteins described herein, operatively linked to promoter and / or enhancer structures from a mammary gland specific gene, like casein or beta-lactoglobulin. The animal may be non-human mammals, most preferably mice, rats, sheep, calves, dogs, monkeys or apes.Binding to target antigen

[0304] Methods for determining the successful binding of an antigen binding protein of the invention to its target antigen (ie CD80) are well known in the art. Non-limiting examples of such methods are described herein in the Examples. Methods for confirmation of the specificity and binding affinity of an antigen binding protein include use of Western blotting, ELISA, immunohistochemistry and Biacore methods, which are all within the skill set of a person skilled in the art.Binding to CD80 and blockade of the CD28:CD80 interaction

[0305] It will be appreciated that in preferred embodiments, upon binding of the antigen binding protein of the invention to CD80, CD28 is prevented (or partially prevented) from binding to CD80.

[0306] The skilled person will be familiar with methods for determining the binding of any antigen binding protein of the invention to CD80, including according to any of the methods described herein in the Examples.

[0307] Moreover, the skilled person will be able to determine the binding of an antigen binding protein to CD80, including whether a protein of the invention thereby blocks the binding of CD28 to CD80. In other words, it will be within the purview of the skilled person to determine whether, upon binding of a protein of the invention to CD80, CD28 is capable of binding to CD80, including in comparison to other known CD80 binding proteins. Such methods are also described herein, in the Examples.

[0308] Further examples of methods for determining binding of a protein to CD80 and / or extent of blocking of the CD28:CD80 interaction by an antibody of the invention are described in Oxley et al., (2024) Cell Reports, 43:114834, incorporated herein by reference.Compositions

[0309] The antigen binding proteins of the invention can be provided in a pharmaceutically acceptable composition for administration to an individual in need thereof. For example the antigen binding proteins made in accordance with the present invention find utility in the treatment of various conditions in which immunosuppression is desired, such as in the treatment of various inflammatory diseases or conditions.

[0310] Pharmaceutical compositions are also contemplated wherein an antigen binding protein as disclosed herein and one or more additional therapeutically active agents are formulated. Formulations of the antigen binding proteins disclosed herein are prepared for storage by mixing said antigen binding protein having the desired degree of purity with optional pharmaceutically acceptable carriers, excipients or stabilizers (Remington's Pharmaceutical Sciences 16th edition, Osol, A. Ed., 1980, incorporated entirely by reference), in the form of lyophilized formulations or aqueous solutions.

[0311] Acceptable carriers, excipients, or stabilizers are nontoxic to recipients at the dosages and concentrations employed, and include buffers such as phosphate, citrate, acetate, and other organic acids; antioxidants including ascorbic acid and methionine; preservatives (such as octadecyldimethylbenzyl ammonium chloride; hexamethonium chloride; benzalkonium chloride, benzethonium chloride; phenol, butyl orbenzyl alcohol; alkyl parabens such as methyl or propyl paraben; catechol; resorcinol; cyclohexanol; 3- pentanol; and m-cresol); low molecular weight (less than about 10 residues) polypeptides; proteins, such as serum albumin, or gelatin; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, histidine, arginine, or lysine; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrins; chelating agents such as EDTA; sugars such as sucrose, mannitol, trehalose or sorbitol; sweeteners and other flavoring agents; fillers such as microcrystalline cellulose, lactose, corn and other starches; binding agents; additives; coloring agents; salt-forming counter-ions such as sodium; metal complexes (e.g. Zn- protein complexes); and / or non-ionic surfactants such as TWEEN™, PLURONICS™ or polyethylene glycol (PEG).

[0312] In one embodiment, the pharmaceutical composition that comprises the antigen binding proteins disclosed herein may be in a water-soluble form, such as being presentas pharmaceutically acceptable salts, which is meant to include both acid and base addition salts. “Pharmaceutically acceptable acid addition salt” refers to those salts that retain the biological effectiveness of the free bases and that are not biologically or otherwise undesirable, formed with inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid and the like, and organic acids such as acetic acid, propionic acid, glycolic acid, pyruvic acid, oxalic acid, maleic acid, malonic acid, succinic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, salicylic acid and the like. “Pharmaceutically acceptable base addition salts” include those derived from inorganic bases such as sodium, potassium, lithium, ammonium, calcium, magnesium, iron, zinc, copper, manganese, aluminium salts and the like. Some embodiments include at least one of the ammonium, potassium, sodium, calcium, and magnesium salts. Salts derived from pharmaceutically acceptable organic non-toxic bases include salts of primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines and basic ion exchange resins, such as isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, and ethanolamine. The formulations to be used for in vivo administration may be sterile. This is readily accomplished by filtration through sterile filtration membranes or other methods.

[0313] The antigen binding proteins disclosed herein may also be formulated as immunoliposomes. A liposome is a small vesicle comprising various types of lipids, phospholipids and / or surfactant that is useful for delivery of a therapeutic agent to a mammal. Liposomes containing the antigen binding proteins are prepared by methods known in the art. The components of the liposome are commonly arranged in a bilayer formation, similar to the lipid arrangement of biological membranes. Particularly useful liposomes can be generated by the reverse phase evaporation method with a lipid composition comprising phosphatidylcholine, cholesterol and PEG-derivatized phosphatidylethanolamine (PEG-PE). Liposomes are extruded through filters of defined pore size to yield liposomes with the desired diameter.

[0314] The antigen binding proteins and other therapeutically active agents may also be entrapped in microcapsules prepared by methods including but not limited to coacervation techniques, interfacial polymerization (for example usinghydroxymethylcellulose or gelatin-microcapsules, or poly-(methylmethacylate) microcapsules), colloidal drug delivery systems (for example, liposomes, albumin microspheres, microemulsions, nano-particles and nanocapsules), and macroemulsions. Such techniques are disclosed in Remington's Pharmaceutical Sciences 16th edition, Osol, A. Ed., 1980, incorporated entirely by reference. Sustained-release preparations may be prepared. Suitable examples of sustained-release preparations include semipermeable matrices of solid hydrophobic polymer, which matrices are in the form of shaped articles, e.g. films, or microcapsules. Examples of sustained-release matrices include polyesters, hydrogels (for example poly(2-hydroxyethyl-methacrylate), or poly(vinylalcohol)), polylactides, copolymers of L-glutamic acid and gamma ethyl-L- glutamate, non-degradable ethylene-vinyl acetate, degradable lactic acid-glycolic acid copolymers such as the Lupron Depot® (which are injectable microspheres composed of lactic acid-glycolic acid copolymer and leuprolide acetate), poly-D-(-)-3-hydroxybutyric acid, and ProLease® (commercially available from Alkermes), which is a microspherebased delivery system composed of the desired bioactive molecule incorporated into a matrix of poly-DL-lactide-co-glycolide (PLG).Methods of treatment

[0315] The antigen binding proteins disclosed herein may find use in a wide range of products. In one embodiment an antigen binding protein disclosed herein is a therapeutic, a diagnostic, or a research reagent. The antigen binding proteins may find use in a composition that is monoclonal or polyclonal. The antigen binding proteins disclosed herein may be used for therapeutic purposes. The antigen binding proteins may be administered to a patient to treat disorders.

[0316] A “patient” for the purposes disclosed herein includes both humans and other animals, e.g., other mammals. Thus the antigen binding proteins disclosed herein have both human therapy and veterinary applications. The term “treatment” or “treating” as disclosed herein is meant to include therapeutic treatment, as well as prophylactic, measures for a disease or disorder. Thus, for example, successful administration of an antigen binding proteins prior to onset of the disease results in treatment of the disease. As another example, successful administration of an optimized antigen binding proteins after clinical manifestation of the disease to combat the symptoms of the diseasecomprises treatment of the disease. “Treatment” and “treating” also encompasses administration of an optimized antigen binding proteins after the appearance of the disease in order to eradicate the disease. Successful administration of an agent after onset and after clinical symptoms have developed, with possible abatement of clinical symptoms and perhaps amelioration of the disease, comprises treatment of the disease. Those “in need of treatment” include mammals already having the disease or disorder, as well as those prone to having the disease or disorder, including those in which the disease or disorder is to be prevented.

[0317] The antigen binding proteins described herein are preferably used to treat a disease or condition in which suppression of an immune response may be desirable.

[0318] The antigen binding proteins described herein are preferably used to treat an immune related condition or disorder. Immune related conditions include but are not limited to autoimmune diseases, inflammatory disorders, and prevention of immune response associated with rejection of donor tissue.

[0319] The antigen binding proteins described herein may be used to treat autoimmune diseases. “Autoimmune diseases” herein include allogenic islet graft rejection, alopecia areata, ankylosing spondylitis, antiphospholipid syndrome, autoimmune Addison's disease, antineutrophil cytoplasmic autoantibodies (ANCA), autoimmune diseases of the adrenal gland, autoimmune hemolytic anemia, autoimmune hepatitis, autoimmune myocarditis, autoimmune neutropenia, autoimmune oophoritis and orchitis, autoimmune thrombocytopenia, autoimmune urticaria, Behcet's disease, bullous pemphigoid, cardiomyopathy, Castleman's syndrome, celiac spruce-dermatitis, chronic fatigue immune disfunction syndrome, chronic inflammatory demyelinating polyneuropathy, Churg-Strauss syndrome, cicatrical pemphigoid, CREST syndrome, cold agglutinin disease, Crohn's disease, dermatomyositis, discoid lupus, essential mixed cryoglobulinemia, factor VIII deficiency, fibromyalgia-fibromyositis, glomerulonephritis, Grave's disease, Guillain-Barre, Goodpasture's syndrome, graft-versus-host disease (GVHD), Hashimoto's thyroiditis, hemophilia A, idiopathic pulmonary fibrosis, idiopathic thrombocytopenia purpura (ITP), IgA neuropathy, IgM polyneuropathies, immune mediated thrombocytopenia, juvenile arthritis, Kawasaki's disease, lichen plantus, lupus erthematosis, Meniere's disease, mixed connective tissue disease, multiple sclerosis,type 1 diabetes mellitus, myasthenia gravis, pemphigus vulgaris, pernicious anemia, polyarteritis nodosa, polychrondritis, polyglandular syndromes, polymyalgia rheumatica, polymyositis and dermatomyositis, primary agammaglobinulinemia, primary biliary cirrhosis, psoriasis, psoriatic arthritis, Reynauld's phenomenon, Reiter's syndrome, rheumatoid arthritis, sarcoidosis, scleroderma, Sjorgen's syndrome, solid organ transplant rejection, stiff-man syndrome, systemic lupus erythematosus, takayasu arteritis, temporal arteristis I giant cell arteritis, thrombotic thrombocytopenia purpura, ulcerative colitis, uveitis, vasculitides such as dermatitis herpetiformis vasculitis, vitiligo, and Wegner's granulomatosis.

[0320] The antigen binding proteins described herein may be used to treat inflammatory disorders. “Inflammatory disorders” herein include acute respiratory distress syndrome (ARDS), acute septic arthritis, adjuvant arthritis, juvenile idiopathic arthritis, allergic encephalomyelitis, allergic rhinitis, allergic vasculitis, allergy, asthma, atherosclerosis, chronic inflammation due to chronic bacterial or viral infectionis, chronic obstructive pulmonary disease (COPD), coronary artery disease, encephalitis, inflammatory bowel disease, inflammatory osteolysis, inflammation associated with acute and delayed hypersensitivity reactions, inflammation associated with tumors, peripheral nerve injury or demyelinating diseases, inflammation associated with tissue trauma such as burns and ischemia, inflammation due to meningitis, multiple organ injury syndrome, pulmonary fibrosis, sepsis and septic shock, Stevens-Johnson syndrome, undifferentiated arthropy, and undifferentiated spondyloarthropathy.

[0321] The antigen binding proteins described herein may be used to prevent or suppressing an immune response associated with rejection of a donor tissue, cell, graft, or organ transplant by a recipient subject. Graft-related diseases or disorders include graft versus host disease (GVDH), such as associated with bone marrow transplantation, and immune disorders resulting from or associated with rejection of organ, tissue, or cell graft transplantation (e.g., tissue or cell allografts or xenografts), including, e.g., grafts of skin, muscle, neurons, islets, organs, parenchymal cells of the liver, etc. With regard to a donor tissue, cell, graft or solid organ transplant in a recipient subject, it is believed such molecules of the invention disclosed herein may be effective in preventing acute rejection of such transplant in the recipient and / or for long-term maintenance therapy to preventrejection of such transplant in the recipient (e.g., inhibiting rejection of insulin-producing islet cell transplant from a donor in the subject recipient suffering from diabetes).

[0322] Preferred immune related disorders that may be treated by the antigen binding proteins disclosed herein include Crohn's disease, systemic lupus erythematosus (SLE), lupus nephritis, psoriatic arthritis, psoriasis, rheumatoid arthritis, ulcerative colitis, and transplant rejection, including but not limited to kidney transplant, liver transplant, and pancreatic transplant.

[0323] Administration of the pharmaceutical composition comprising an antigen binding protein disclosed herein, e.g., in the form of a sterile aqueous solution, may be done in a variety of ways, including, but not limited to orally, subcutaneously, intravenously, intranasally, intraotically, transdermally, topically (e.g., gels, salves, lotions, creams, etc.), intraperitoneally, intramuscularly, intrapulmonary, vaginally, parenterally, rectally, or intraocularly. In some instances, for example for the treatment of wounds etc., the antigen binding protein may be directly applied as a solution or spray. As is known in the art, the pharmaceutical composition may be formulated accordingly depending upon the manner of introduction.

[0324] Subcutaneous administration may be used in circumstances where the patient may self-administer the pharmaceutical composition. Many protein therapeutics are not sufficiently potent to allow for formulation of a therapeutically effective dose in the maximum acceptable volume for subcutaneous administration. This problem may be addressed in part by the use of protein formulations comprising arginine-HCI, histidine, and polysorbate, antigen binding proteins disclosed herein may be more amenable to subcutaneous administration due to, for example, increased potency, improved serum half-life, or enhanced solubility. As is known in the art, protein therapeutics are often delivered by IV infusion or bolus. The antigen binding proteins disclosed herein may also be delivered using such methods. For example, administration may be by intravenous infusion with 0.9% sodium chloride as an infusion vehicle.

[0325] Pulmonary delivery may be accomplished using an inhaler or nebulizer and a formulation comprising an aerosolizing agent. For example, AERx® inhalable technology commercially available from Aradigm, or Inhance™ pulmonary delivery systemcommercially available from Nektar Therapeutics may be used. Furthermore, antigen binding proteins disclosed herein may be amenable to oral delivery.

[0326] In addition, any of a number of delivery systems are known in the art and may be used to administer the antigen binding proteins disclosed herein. Examples include, but are not limited to, encapsulation in liposomes, microparticles, microspheres (e.g., PLA / PGA microspheres), and the like. Alternatively, an implant of a porous, non-porous, or gelatinous material, including membranes or fibers, may be used. Sustained release systems may comprise a polymeric material or matrix such as polyesters, hydrogels, poly(vinylalcohol), polylactides, copolymers of L-glutamic acid and ethyl-L-gutamate, ethylene-vinyl acetate, lactic acid-glycolic acid copolymers such as the Lupron Depot®, and poly-D-(-)-3-hydroxyburyric acid. It is also possible to administer a nucleic acid encoding an antigen binding protein disclosed herein, for example by retroviral infection, direct injection, or coating with lipids, cell surface receptors, or other transfection agents. In all cases, controlled release systems may be used to release the antigen binding protein disclosed herein, at or close to the desired location of action.

[0327] The dosing amounts and frequencies of administration are, in one embodiment, selected to be therapeutically or prophylactically effective. As is known in the art, adjustments for protein degradation, systemic versus localized delivery, and rate of new protease synthesis, as well as the age, body weight, general health, sex, diet, time of administration, drug interaction and the severity of the condition may be necessary, and will be ascertainable with routine experimentation by those skilled in the art.

[0328] The concentration of the therapeutically active antigen binding proteins in the formulation may vary from about 0.1 to 100 weight %. In one embodiment, the concentration of the antigen binding proteins is in the range of 0.003 to 1 .0 molar. In order to treat a patient, a therapeutically effective dose of the antigen binding protein disclosed herein may be administered. By “therapeutically effective dose” herein is meant a dose that produces the effects for which it is administered. The exact dose will depend on the purpose of the treatment, and will be ascertainable by one skilled in the art using known techniques. Dosages may range from 0.0001 to 100 mg / kg of body weight or greater, for example 0.1 , 1 , 10, or 50 mg / kg of body weight. In one embodiment, dosages range from 1 to 10mg / kg.

[0329] In some embodiments, only a single dose of the antigen binding protein is used. In other embodiments, multiple doses of the antigen binding protein are administered. The elapsed time between administrations may be less than 1 hour, about 1 hour, about 1-2 hours, about 2-3 hours, about 3-4 hours, about 6 hours, about 12 hours, about 24 hours, about 48 hours, about 2-4 days, about 4-6 days, about 1 week, about 2 weeks, or more than 2 weeks.

[0330] In other embodiments the antigen binding proteins disclosed herein are administered in metronomic dosing regimens, either by continuous infusion or frequent administration without extended rest periods. Such metronomic administration may involve dosing at constant intervals without rest periods. Typically, such regimens encompass chronic low-dose or continuous infusion for an extended period of time, for example 1-2 days, 1-2 weeks, 1-2 months, or up to 6 months or more. The use of lower doses may minimize side effects and the need for rest periods.Kits

[0331] In another embodiment there is provided a kit or article of manufacture including an antigen binding protein, immunoglobulin variable domain, antibody, dab, scFv, Fab, Fab', F(ab')2, Fv fragment, diabody, triabody, linear antibody, single-chain antibody molecule, or multispecific antibody, fusion protein, conjugate or pharmaceutical composition as described above.

[0332] In other embodiments there is provided a kit for use in a use mentioned above, the kit including:- a container holding a therapeutic composition in the form of one or more of an antigen binding protein, immunoglobulin variable domain, antibody, dab, scFv, Fab, Fab', F(ab')2, Fv fragment, diabody, triabody, linear antibody, single-chain antibody molecule, or multispecific antibody, fusion protein, conjugate or pharmaceutical composition;- a label or package insert with instructions for use.

[0333] The kit or “article of manufacture” may comprise a container and a label or package insert on or associated with the container. Suitable containers include, for example, bottles, vials, syringes, blister pack, etc. The containers may be formed from avariety of materials such as glass or plastic. The container holds a therapeutic composition which is effective for treating the condition and may have a sterile access port (for example the container may be an intravenous solution bag or a vial having a stopper pierceable by a hypodermic injection needle). The label or package insert indicates that the therapeutic composition is used for treating the condition of choice. In one embodiment, the label or package insert includes instructions for use.

[0334] The kit may comprise (a) a therapeutic composition; and (b) a second container with a second active principle or ingredient contained therein. The kit in this embodiment of the invention may further comprise a package insert indicating that the and other active principle can be used to treat a disorder or prevent a complication stemming from an inflammatory condition. Alternatively, or additionally, the kit may further comprise a second (or third) container comprising a pharmaceutically-acceptable buffer, such as bacteriostatic water for injection (BWFI), phosphate-buffered saline, Ringer's solution and dextrose solution. It may further include other materials desirable from a commercial and user standpoint, including other buffers, diluents, filters, needles, and syringes.

[0335] In certain embodiments the therapeutic composition may be provided in the form of a device, disposable or reusable, including a receptacle for holding the therapeutic composition. In one embodiment, the device is a syringe. The device may hold 1-2 mL of the therapeutic composition. The therapeutic composition may be provided in the device in a state that is ready for use or in a state requiring mixing or addition of further components.

[0336] In other embodiments there is provided a kit for use in a diagnostic application mentioned above, the kit including:- a container holding a diagnostic composition in the form of one or more of an antigen binding protein, immunoglobulin variable domain, antibody, Fab, dab, scFv, diabody, triabody, fusion protein or conjugate;- a label or package insert with instructions for use.

[0337] The kit may comprise (a) a diagnostic composition; and (b) a second container with a second diagnostic agent or second label contained therein. It may further includeother materials desirable from a commercial and user standpoint, including other buffers, diluents, filters etc.

[0338] It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

[0339] The examples that follow are intended to illustrate but in no way limit the present invention.ExamplesThe inventors have generated a series of antibodies for binding to CD80, and that thereby prevent the binding of CD28 to CD80.Example 1 : Materials and methods

[0340] Cell culture. Cells were cultured at 37°C in a 10% CO2 incubator in medium containing 100 U / rnL penicillin, 100 pg / mL streptomycin (Gibco), and 10% FCS (Sigma- Aldrich). Base medium for CHO cells was aMinimal Essential Medium (a-MEM; Gibco), for the 293T Dulbecco’s Modified Eagle Medium (DMEM; Gibco), and for primary human T cells Roswell Park Memorial Institute 1640 Medium (RPMI 1640; Gibco). Cells were detached for passaging or harvest with Trypsin-EDTA (Gibco). For retrovirus production, expression and packaging vectors were introduced into 293T cells by calcium phosphate transfection, and retroviral transduction of CHO cells was performed using standard protocols.

[0341] Flow cytometry of cultured cells. Harvested cells were washed with PBS. To assess binding of proteins, cells were incubated with 50 pL of 10-100 pg / mL protein for 20 min unless otherwise stated, washed and then stained with the relevant anti-Fc secondary antibody for a further 20 min. After washing to remove excess protein and antibody, cell pellets were resuspended in 100 pL of FACS buffer (PBS with 10% FCS). Flow cytometry was performed on viable cells (based on SSC / FSC) using a BD LSRII or LSRFortessa (BD Biosciences). Human PD-L1 was detected using PD-L1-PE (clone MIH1 , Thermo Fisher). Antibodies and proteins were detected using anti-hlgG1-APC(clone IS11-12E4.23.20, Miltenyi), and anti-mlgG2a-PE-Cy7 (clone m2a-15F8, ThermoFisher) secondaries.

[0342] Basement membrane glomerulonephritis experimental model. 6-10 week old transgenic C57BL / 6 mice with double knockin humanised CD80 and PD-L1 were housed in specific pathogen free conditions. Mice were sensitized subcutaneously with 0.5 mg normal sheep globulin in Freund’s complete adjuvant [FCA], Four days later, 4.5 mg sheep anti-mouse GBM globulin was injected intravenously into the tail-vein and 100 g of abatacept and B10 was delivered via intraperitoneal injections on days 5 and 7. On day 8 urine was collected for albuminuria and creatinine measurement.

[0343] CD80mCherry:PD-L1mGFP population analysis. At least 250,000 mCherry / mGFP double positive cells were recorded by flow cytometry. mCherry, mGFP, and free PD-L1 MIH1 MFI values for double positive events were exported. Assuming a 1 :1 infection, mCherry and mGFP MFI values were independently normalised against the average of all double positive events, then mCherry: mGFP ratio was determined for each event. MIH1 MFI and the log2(mCherry:mGFP ratio) for each event was transferred into a Pivot Table. The average MIH1 MFI was determined for events grouped in intervals of 0.1-0.2 log2(mCherry:mGFP ratio). Fold changes were determined for untreated and treated samples.

[0344] Protein expression and purification. For crude supernatant analysis, 293T were plated at 5x105in 10cm plates. Cells were transfected with 5 pg of vector, and washed after 8 hours. Supernatant was collected 3 days later and applied to experiments either directly or after concentration in Microsep Advance Centrifugal Devices (PALL, MCP030C46). For purified proteins, Freestyle™ 293-F cells (Thermo Fisher Scientific) were grown at 37°C, 8% CO2, 130 rpm to a density of 1 xio6 / mL in Freestyle 293 expression medium, and transiently transfected with plasmid DNA and polyethyleneimine (PEI) at a 3:1 PEI: DNA ratio (1 mg DNA per L). Cells were grown for 7 days after transfection, supplemented with Glutamax (Thermo Fisher Scientific), 0.2 mM butyric acid (Sigma- Aldrich) and 5 g / L lupin (Solabia) 1 and 4 days after transfection. Secreted recombinant protein was purified from the supernatant using Protein G resin (Cytiva). Protein was concentrated and applied to a Superdex 200 size exclusion column (Cytiva)equilibrated in DPBS (Gibco). Purest fractions as judged by non-reducing SDS-PAGE were combined, concentrated and filter sterilised, and stored at 4°C.

[0345] Primary human T cell assays. Consenting blood donors were healthy controls enrolled in a low-risk ethics study to examine blood leukocyte subset analysis (Monash University 2020-26385 and 2022-35867) in accordance with the principles of the Declaration of Helsinki and approved by the Monash University Human Research Ethics Committee (M UH REC). T cells were purified (>95%) from thawed buffy coats by MACS cell separation using human CD3 MicroBeads (Miltenyi Biotec). T cells were stained with 2.5 pM CFSE (Invitrogen) for 10 min for proliferation assays. Cells were seeded at 50,000 T cells / well in flat bottom 96-well plates pre-seeded with 10,000 CHO aAPC cells. Cells were co-cultured in 200 pL RPMI with 10% FCS and penicillin / streptomycin. Treatments were 50 pL of concentrated crude supernatant. At harvest, viable T cells were gated based on Sytox Blue (Thermo Fisher) negativity. T cell proliferation was assessed by CFSE dilution by flow cytometry. T cell activation was assessed by CD69 surface expression. For cytokine assays, 2x106T cells were plated with 3x105CHO aAPC cells for 3-4 days in a 6-well plate, after which they were replated into 96-well plates with Brefeldin A (3 pg / mL) and Monensin (2 pM) in the presence of CD80 antibodies (40-50 pg / mL) with or without nivolumab (100 pg / mL). After 8-12 hours cells were detached and stained for CD4 (clone SK3, BioLegend) and CD8 (clone SK1 , BioLegend), then fixed with 100pL of IC Fixation Buffer (Thermo Fisher Scientific). Cells were stained with anti- IL2 (clone MQ1-17H12, BioLegend) and anti-IFNy (clone 4S.B3, BioLegend) in Permeabilization Buffer (Thermo Fisher Scientific), washed, and resuspended in FACS buffer for analysis.Example 2: Generation of novel anti-CD80 antibodies

[0346] Mice were immunized with four injections of the murine pre-B-cell line 300.19 retrovirally expressing human CD80. Isolated B cells were analysed using the Beacon platform (Berkeley Lights), screening for antibody producing B cells that bind CHO cells retrovirally expressing human CD80, positive or negative binding to the same CHO prebound by MEDI5265-lg, positive binding to CHO retrovirally expressing chimeric mouse CD80 with human membrane-distal domain, and positive binding to anti-IgG beads. cDNA was made from select B cells and sequenced.Example 3: Characterisation of antibodies

[0347] Figure 1 compares the binding to CD80 of an exemplary antibody of the specification (antibody B10, having a VH as set forth in SEQ ID NO: 79 and a VL as set forth in SEQ ID NO: 146) with abatacept.

[0348] Figure 1A shows the results of a flow cytometry experiment of cis-CD80:PD-L1 cells comparing abatacept and B10 binding to CD80 (hl gG 1 staining), effect on cis-bound PD-L1 (MIH1 staining), and ability to block co-stimulation (CD28-lg binding).

[0349] Figure 1 B shows the binding of high-affinity CTLA4-lg (CTLA4HA-lg; high affinity CD28 surrogate) to cells expressing surface CD80 in competition with a dose / response of abatacept and B10. Overall, the results show that B10 has greater CTLA4HA-lg displacement relative to abatacept - indicating that the binding affinity of B10 to CD80 - and the ability to prevent binding of CD28 to CD80 is higher.

[0350] Figure 2 provides examples for the CD80 antibodies 2B2, B10, 2B17, and 2B26 compared to abatacept and TKMF5. The CD80 binding (hlgG1 staining), effect on cis- bound PD-L1 (free PD-L1 by MIH1 staining), and CD28 blockade (percent of CD28-Fc binding blocked) on cis-CD80:PD-L1 cells is shown. Abatacept blocks CD28-Fc binding and liberates some PD-L1 , whereas the CD80 antibody TKMF5 liberates PD-L1 but neglects to block CD28-lg. The novel CD80 antibodies block CD28 binding but have minor impact on c / s-bound PD-L1.

[0351] Figure 3 shows the results of flow cytometry of CD28-lg binding (mlgG2a staining) on cis-CD80:PD-L1 cells. Binding is completely blocked by treatment with abatacept or B10, and only partially blocked by galiximab (a prior art anti-CD80 antibody). B10 and galiximab were produced in crude supernatant. Nonetheless, the differences in blockade observed are expected to represent differences in both affinity and antibody production, such that B10 is expected to have a higher affinity for CD80 compared to a prior art antibody.Example 4: Immunosuppressive effect of antibodies of the invention

[0352] An in vitro experiment was conducted to compare activation of primary human T cell (as assessed by the percentage of IL-2+ T cells) following 4 day co-culture withartificial antigen presenting cells (aAPCs) expressing a 1:1 ratio of CD80:PD-L1 and cell surface 0KT3scFv. 50 pg / mL of abatacept or B10 were added in the final 8 hours of coculture. A schematic is shown in Figure 4A.

[0353] Figure 4B shows a dose / response of the experimental conditions described above, showing reduced CD4 and CD8 T cell activity by B10 relative to abatacept.

[0354] Figure 4C shows activity of CD4 T cells (treated as described in Figure 4), demonstrating partial contribution of PD-1 signalling by abatacept by addition of an anti- PD-1 antibody (nivolumab). In contrast, T cell suppression by B10 is independent of PD- 1 signalling.

[0355] The anti-GBM mouse model of glomerulonephritis is employed where mice develop inflammatory kidney disease. Mice are administered biologies to alleviate disease.

[0356] Figure 5A provides a schematic of the humanisation strategy for mouse CD80 and PD-L1 genes. Homologous human sequences replace exon 2 of mouse CD80, which encodes the IgV domain bound by the human CD80 antibodies, and exon 3 of mouse PD-L1. Double knockin (DKI) mice maintain endogenous regulation and expression CD80 and PD-L1 , and retain binding in cis to each other as well as in trans to CD28, CTLA4, or PD-1.

[0357] Figure 5B provides a schematic of the anti-GBM glomerulonephritis mouse model of kidney autoimmunity.

[0358] The results are shown in Figure 5C. The B10 antibody provided for improved protection from kidney damage, as measured by the urine albumin:creatinine ratio (uACR), compared to abatacept. These results indicate that the antibodies of the invention are also capable of providing in vivo immunosuppression, and are demonstrated to have improved immunosuppressive capacity compared to abatacept.

[0359] Overall, these findings indicate that the CD28-blocking CD80 antibody B10 provides both potent T cell suppression in vitro and immunosuppression in vivo, with potential for improved therapeutic outcomes for patients relative to abatacept.

[0360] It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Claims

CLAIMS1. An antigen binding protein for binding to CD80, wherein the protein comprises an antigen binding domain comprising: a CDRH1 , a CDRH2 and / or a CDRH3 of an antigen binding domain having a variable heavy chain as defined in any one of SEQ ID NOs: 78, 79, 80, 81 , 82, 83 or 84; and / or a CDRL1 , a CDRL2 and / or a CDRL3 of an antigen binding domain having a variable heavy chain as defined in any one of SEQ ID NOs: 145, 146, 147, 148, 149, 150, or 151.

2. The antigen binding protein of claim 1 , wherein the antigen binding protein inhibits the binding of CD28 to CD80.

3. The antigen binding protein of claim 1 or 2, wherein the antigen binding protein competitively inhibits the binding to CD80 of an antibody:- comprising a VH comprising a sequence as set forth in SEQ ID NO: 79 and a VL comprising a sequence as set forth in SEQ ID NO: 146;- comprising a VH comprising a sequence as set forth in SEQ ID NO: 78 and a VL comprising a sequence as set forth in SEQ ID NO: 145;- comprising a VH comprising a sequence as set forth in SEQ ID NO: 80 and a VL comprising a sequence as set forth in SEQ ID NO: 147;- comprising a VH comprising a sequence as set forth in SEQ ID NO: 81 and a VL comprising a sequence as set forth in SEQ ID NO: 148;- comprising a VH comprising a sequence as set forth in SEQ ID NO: 82 and a VL comprising a sequence as set forth in SEQ ID NO: 149;- comprising a VH comprising a sequence as set forth in SEQ ID NO: 83 and a VL comprising a sequence as set forth in SEQ ID NO: 150; or- comprising a VH comprising a sequence as set forth in SEQ ID NO: 84 and a VL comprising a sequence as set forth in SEQ ID NO: 151.

4. The antigen binding protein of any one of claims 1 to 3, wherein the protein comprises:- a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable heavy chain as defined in SEQ ID NO: 79, and a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable light chain as defined in SEQ ID NO: 146;- a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable heavy chain as defined in SEQ ID NO: 78, and a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable light chain as defined in SEQ ID NO: 145;- a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable heavy chain as defined in SEQ ID NO: 80, and a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable light chain as defined in SEQ ID NO: 147;- a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable heavy chain as defined in SEQ ID NO: 81, and a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable light chain as defined in SEQ ID NO: 148;- a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable heavy chain as defined in SEQ ID NO: 82, and a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable light chain as defined in SEQ ID NO: 149;- a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable heavy chain as defined in SEQ ID NO: 83, and a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable light chain as defined in SEQ ID NO: 150; or- a CDR1, a CDR2 and a CDR3 of an antigen binding domain having a variable heavy chain as defined in SEQ ID NO: 84, and a CDR1, a CDR2 and a CDR3 ofan antigen binding domain having a variable light chain as defined in SEQ ID NO: 151.

5. The antigen binding protein of any one of claims 1 to 4, comprising, consisting essentially of or consisting of the amino acid sequence of (in order of N to C terminus or C to N terminus) SEQ ID NOs: 79 and 146.

6. The antigen binding protein of any one of claims 1 to 4, comprising, consisting essentially of or consisting of the amino acid sequence of (in order of N to C terminus or C to N terminus) SEQ ID NOs: 78 and 145.

7. The antigen binding protein of any one of claims 1 to 4, comprising, consisting essentially of or consisting of the amino acid sequence of (in order of N to C terminus or C to N terminus) SEQ ID NOs: 80 and 147.

8. The antigen binding protein of any one of claims 1 to 4, comprising, consisting essentially of or consisting of the amino acid sequence of (in order of N to C terminus or C to N terminus) SEQ ID NOs: 81 and 148.

9. The antigen binding protein of any one of claims 1 to 4, comprising, consisting essentially of or consisting of the amino acid sequence of (in order of N to C terminus or C to N terminus) SEQ ID NOs: 82 and 149.

10. The antigen binding protein of any one of claims 1 to 4, comprising, consisting essentially of or consisting of the amino acid sequence of (in order of N to C terminus or C to N terminus) SEQ ID NOs: 83 and 150.

11. The antigen binding protein of any one of claims 1 to 4, comprising, consisting essentially of or consisting of the amino acid sequence of (in order of N to C terminus or C to N terminus) SEQ ID NOs: 84 and 151.

12. The antigen binding protein of any one of claims 1 to 5, wherein the protein comprises an antigen binding domain comprising:(i) a VH comprising a complementarity determining region (CDR) 1 comprising a sequence as set forth in SEQ ID NO: 1 (IMGT) or 16 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least87%, at least 88%, at least 89%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; a CDR2 comprising a sequence as set forth in SEQ ID NO: 2 (IMGT) or 17 or 164 (Kabat), or a sequence at least 80%, at least 81 %, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; and a CDR3 comprising a sequence as set forth in SEQ ID NO: 4 (IMGT) or 18 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(ii) a VH comprising a sequence as set forth in SEQ ID NO: 79 or 83, or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(iii) a VL comprising a complementarity determining region (CDR) 1 comprising a sequence as set forth in SEQ ID NO: 85 (IMGT) or 97 (Kabat) or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; a CDR2 comprising a sequence as set forth in SEQ ID NO: 86 (IMGT) or 98 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto; and a CDR3 comprising a sequence as set forth in SEQ ID NO: 87 (IMGT) or 99 (Kabat), or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(iv) a VL comprising a sequence as set forth in SEQ ID NO: 146 or 150, or a sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto;(v) a VH comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 1 , a CDR2 comprising a sequence set forth in SEQ ID NO: 2, and a CDR3 comprising a sequence set forth in SEQ ID NO: 4; or comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 16, a CDR2 comprising a sequence set forth in SEQ ID NO: 17 or 164, and a CDR3 comprising a sequence set forth in SEQ ID NO: 18;(vi) a VL comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 85, a CDR2 comprising a sequence set forth in SEQ ID NO: 86, and a CDR3 comprising a sequence as set forth in SEQ ID NO: 87; or comprising a CDR1 comprising a sequence set forth in SEQ ID NO: 97, a CDR2 comprising a sequence set forth in SEQ ID NO: 98 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 99;(vii) a VH comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 1 , a CDR2 comprising a sequence as set forth in SEQ ID NO: 2, and a CDR3 comprising a sequence as set forth in SEQ ID NO: 4; and a VL comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 85, a CDR2 comprising a sequence as set forth in SEQ ID NO: 86, and a CDR3 comprising a sequence as set forth in SEQ ID NO: 87; or a VH comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 16, a CDR2 comprising a sequence as set forth in SEQ ID NO: 17 or 164 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 18; and a VL comprising a CDR1 comprising a sequence as set forth in SEQ ID NO: 97, a CDR2 comprising a sequence as set forth in SEQ ID NO: 98 and a CDR3 comprising a sequence as set forth in SEQ ID NO: 99;(viii) a VH comprising a sequence as set forth in SEQ I D NO: 79, and a VL comprising a sequence set forth in SEQ ID NO: 146; or(viv) a VH comprising a sequence as set forth in SEQ ID NO: 83, and a VL comprising a sequence set forth in SEQ ID NO: 150.

13. The antigen binding protein of claim 12, wherein the protein further comprises at least one of:(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 32 or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 29, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 33, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 31 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 111 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 108, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 112, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 110, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; or(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 55, or a sequence at least about 80%, at least 85%, at least 90%, at least91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 56 or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 57, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 58, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 130, or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 131 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 132, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 110, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; or(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 44, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 45, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%,at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 46, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 47, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and(ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 122, or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 123, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 124, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 110, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; or(i) a VH comprising a framework region (FR) 1 comprising an amino acid sequence of SEQ ID NO: 71 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 72, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 73, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acidsequence of SEQ ID NO: 74, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto; and ii) a VL comprising a FR1 comprising an amino acid sequence of SEQ ID NO: 140, or a sequence at least about 80%, at least 85%, at least 90%, at least 91 %, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR2 comprising an amino acid sequence of SEQ ID NO: 141 , or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical thereto; a FR3 comprising an amino acid sequence of SEQ ID NO: 142, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical thereto, and a FR4 comprising an amino acid sequence of SEQ ID NO: 110, or a sequence at least about 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% thereto.

14. The antigen binding protein of claim 12 or 13, wherein the antigen binding protein comprises a variable heavy chain comprising the amino acid sequence as set forth in SEQ ID NO: 79 or 83, or a sequence at least about 80%, at least about 85%, at least about 90%, at least about 91 %, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identical thereto; and a variable light chain comprising the amino acid sequence as set forth in SEQ I D NO: 146 or 150; or a sequence at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98 %, or at least about 99% identical thereto; wherein the variable heavy and / or light chains comprise no more than 1 , no more than 2, no more than 3, no more than 4, no more than 5, no more than 6, no more than 7, no more than 8, no more than 9, no more than 10, no more than 11 , no more than 12, no more than 13, no more than 14, no more than 15, no more than 16, no more than 17, no more than 18, no more than 19 or no more than 20 amino acid residue substitutions, deletions, oradditions or combination thereof, outside the indicated CDR sequences, and wherein the antigen binding protein retains the ability to bind to CD80.

15. The antigen binding protein of any one of claims 1 to 14, wherein the antigen binding protein is in the form of:(i) a single domain antibody (sdAb);)(ii) a single chain Fv fragment (scFv);(iii) a variable domain;(iv) a dimeric scFv (di-scFv); or(v) one of (i) or (iv) linked to a constant region of an antibody, Fc or a heavy chain constant domain (CH) 2 and / or CH3.

16. The antigen binding protein of any one of claims 1 to 15, wherein the antigen binding protein is in the form of:(i) a diabody;(ii) a triabody;(iii) a tetrabody;(iv) a Fab;(v) a F(ab’)2;(vi) a Fv;(vii) a bispecific, trispecific antibody or other form of multispecific antibody (including a BiTE); or(viii) one of (i) to (vii) linked to a constant region of an antibody, Fc or a heavy chain constant domain (CH) 2 and / or CH3.

17. The antigen binding protein of any one of claims 1 to 16, wherein the protein is a monoclonal antibody.

18. The antigen binding protein of any one of claims 1 to 17, wherein the protein is a naked antibody.

19. The antigen binding protein of any one of claims 1 to 18, wherein the protein is in the form of a fusion protein.

20. The antigen binding protein of any one of claims 1 to 19, wherein the protein comprises a chemical modification, such as conjugation to an active agent or radiolabel, or an agent for improving solubility.

21. A nucleic acid molecule encoding an antigen binding protein of any one of claims 1 to 19.

22. A vector or expression construct comprising the nucleic acid of claim 21.

23. A recombinant host cell comprising the nucleic acid of claim 21 or the vector or expression construct of claim 22.

24. A pharmaceutical composition comprising an antigen binding protein of any one of claims 1 to 19 and a pharmaceutically acceptable carrier, diluent or excipient.

25. A method of treating an inflammatory disorder in a subject in need thereof, the method comprising administering to said subject, an antigen binding protein of any one of claims 1 to 19 or a pharmaceutical composition of claim 24, thereby treating an inflammatory disorder in the subject.

26. Use of an antigen binding protein of any one of claims 1 to 19 in the manufacture of a medicament for treating an inflammatory disorder in a subject in need thereof.

27. The method or use of claim 25 or 26, wherein the inflammatory disorder is an immune related disorder or a condition or disorder requiring immunosuppression.

28. The method or use of claim 27, wherein the immune related disorder or condition or disorder requiring immunosuppression is selected from: Crohn's disease, systemic lupus erythematosus (SLE), lupus nephritis, psoriatic arthritis, psoriasis, rheumatoid arthritis, ulcerative colitis, transplant rejection and or Graft-vs-host disease (GvHD).

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