Anti-CD79b antibodies and uses thereof

Abstract

The invention relates to anti-CD79b (differentiated 79B cluster) antibodies, antigen binding fragments thereof, antibody-drug conjugates (ADCs) derived therefrom, and uses thereof.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to U.S. provisional application 63 / 435,896, filed December 29, 2022. The disclosure of the prior application is considered part of the disclosure of this application and is hereby incorporated in its entirety into this application.

[0003] SEQUENCE LISTING

[0004] The instant application contains a Sequence Listing in XML file format entitled “55679-0002WO1 Sequence list.XML.” The XML file was created on December 6, 2023, and is 69,659 bytes in size. The contents of the XML file are incorporated by reference in their entirety herein. TECHNICAL FIELD

[0005] This summary relates to anti-CD79b (cluster of differentiation 79B) antibodies, antigen-binding fragments thereof, antibody-drug conjugates (ADCs) derived therefrom, and uses thereof. BACKGROUND

[0006] CD79 is a signaling component of the B-cell receptor, functioning as a covalent heterodimer comprising CD79a and CD79b. CD79b comprises an extracellular immunoglobulin (Ig) domain, a transmembrane domain, and an intracellular signaling domain, an immunoreceptor tyrosine-based activation motif (ITAM) domain. CD79b expression is detected on the surface of nearly all non-Hodgkin lymphoma (NHL), acute lymphoblastic leukemia (ALL), and chronic lymphocytic leukemia (CLL) patients.

[0007] CD79b is an attractive therapeutic target for B-cell malignancies for several reasons. First, CD79b is not only widely expressed in B-cell malignancies, but expression is unchanged after CD19 or CD20 loss, making this receptor an attractive alternative to CD19 or CD20-targeted therapies. Second, when the B-cell receptor is cross-linked, it targets the major histocompatibility complex class II compartment, a lysosome-like compartment, as part of B-cell presentation of class II antigens.

[0008] Given the important role of CD79b in cancer, there is a need to develop therapeutic agents that target CD79b. SUMMARY

[0009] The present invention relates to anti-CD79b antibodies, antigen-binding fragments thereof, and uses thereof.

[0010] In one aspect, the present disclosure relates to an antibody or antigen-binding fragment thereof that binds CD79b (cluster of differentiation 79B), comprising:

[0011] a heavy chain variable region (VH) comprising complementarity determining regions (CDRs) 1, 2, and 3, wherein the VH CDR1 region comprises an amino acid sequence that is at least 80% identical to a selected VH CDR1 amino acid sequence, the VH CDR2 region comprises an amino acid sequence that is at least 80% identical to a selected VH CDR2, and the VH CDR3 region comprises an amino acid sequence that is at least 80% identical to a selected VH CDR3; and

[0012] a light chain variable region (VL) comprising CDRs 1, 2, and 3, wherein the VL CDR1 region comprises an amino acid sequence that is at least 80% identical to a selected VL CDR1, the VL CDR2 region comprises an amino acid sequence that is at least 80% identical to a selected VL CDR2, and the VL CDR3 region comprises an amino acid sequence that is at least 80% identical to a selected VL CDR3,

[0013] wherein the amino acid sequences of the selected VH CDRs 1, 2, and 3 and the amino acid sequences of the selected VL CDRs 1, 2, and 3 are one of:

[0014] (1) the amino acid sequences of the selected VH CDRs 1, 2, 3 are set forth in SEQ ID NOs: 9, 11, 13, respectively, and the amino acid sequences of the selected VL CDRs 1, 2, 3 are set forth in SEQ ID NOs: 14-16, respectively;

[0015] (2) the amino acid sequences of the selected VH CDRs 1, 2, 3 are set forth in SEQ ID NOs: 19, 21, 23, respectively, and the amino acid sequences of the selected VL CDRs 1, 2, 3 are set forth in SEQ ID NOs: 24-26, respectively;

[0016] (3) the amino acid sequences of the selected VH CDRs 1, 2, 3 are set forth in SEQ ID NOs: 29, 31, 33, respectively, and the amino acid sequences of the selected VL CDRs 1, 2, 3 are set forth in SEQ ID NOs: 24-26, respectively;

[0017] (4) the amino acid sequences of the selected VH CDRs 1, 2, 3 are set forth in SEQ ID NOs: 39, 41, 43, respectively, and the amino acid sequences of the selected VL CDRs 1, 2, 3 are set forth in SEQ ID NOs: 44-46, respectively;

[0018] (5) the amino acid sequences of the selected VH CDRs 1, 2, 3 are set forth in SEQ ID NOs: 49, 51, 53, respectively, and the amino acid sequences of the selected VL CDRs 1, 2, 3 are set forth in SEQ ID NOs: 54-56, respectively.

[0019] (6) The amino acid sequences of the selected VH CDRs 1, 2, and 3 are listed in SEQ ID NOs: 59, 61, and 63, respectively, and the amino acid sequences of the selected VL CDRs 1, 2, and 3 are listed in SEQ ID NOs: 64-66, respectively;

[0020] (7) The amino acid sequences of the selected VH CDRs 1, 2, and 3 are listed in SEQ ID NOs: 10, 12, and 13, respectively, and the amino acid sequences of the selected VL CDRs 1, 2, and 3 are listed in SEQ ID NOs: 14-16, respectively;

[0021] (8) The amino acid sequences of the selected VH CDRs 1, 2, and 3 are listed in SEQ ID NOs: 20, 22, and 23, respectively, and the amino acid sequences of the selected VL CDRs 1, 2, and 3 are listed in SEQ ID NOs: 24-26, respectively;

[0022] (9) The amino acid sequences of the selected VH CDRs 1, 2, and 3 are listed in SEQ ID NOs: 30, 32, and 33, respectively, and the amino acid sequences of the selected VL CDRs 1, 2, and 3 are listed in SEQ ID NOs: 34-36, respectively;

[0023] (10) The amino acid sequences of the selected VH CDRs 1, 2, and 3 are listed in SEQ ID NOs: 40, 42, and 43, respectively, and the amino acid sequences of the selected VLCDRs 1, 2, and 3 are listed in SEQ ID NOs: 44-46, respectively;

[0024] (11) The amino acid sequences of the selected VH CDRs 1, 2, and 3 are listed in SEQ ID NOs: 50, 52, and 53, respectively, and the amino acid sequences of the selected VLCDRs 1, 2, and 3 are listed in SEQ ID NOs: 54-56, respectively;

[0025] (12) The amino acid sequences of the selected VH CDRs 1, 2, and 3 are listed in SEQ ID NOs: 60, 62, and 63, respectively, and the amino acid sequences of the selected VLCDRs 1, 2, and 3 are listed in SEQ ID NOs: 64-66, respectively.

[0026] In some embodiments, according to the Kabat definition, VH comprises the amino acid sequences of CDRs 1, 2, and 3 listed in SEQ ID NOs: 9, 11, and 13, respectively, and VL comprises the amino acid sequences of CDRs 1, 2, and 3 listed in SEQ ID NOs: 14-16, respectively.

[0027] In some embodiments, according to the Kabat definition, VH comprises the amino acid sequences of CDRs 1, 2, and 3 listed in SEQ ID NOs: 19, 21, and 23, respectively, and VL comprises the amino acid sequences of CDRs 1, 2, and 3 listed in SEQ ID NOs: 24-26, respectively.

[0028] In some embodiments, according to the Kabat definition, VH comprises CDRs 1, 2, and 3 having amino acid sequences listed in SEQ ID NOs: 29, 31, and 33, respectively, and VL comprises CDRs 1, 2, and 3 having amino acid sequences listed in SEQ ID NOs: 34-36, respectively.

[0029] In some embodiments, according to the Kabat definition, VH comprises the amino acid sequences of CDRs 1, 2, and 3 listed in SEQ ID NOs: 39, 41, and 43, respectively, and VL comprises the amino acid sequences of CDRs 1, 2, and 3 listed in SEQ ID NOs: 44-46, respectively.

[0030] In some embodiments, according to the Kabat definition, VH comprises the amino acid sequences of CDRs 1, 2, and 3 listed in SEQ ID NOs: 49, 51, and 53, respectively, and VL comprises the amino acid sequences of CDRs 1, 2, and 3 listed in SEQ ID NOs: 54-56, respectively.

[0031] In some embodiments, according to the Kabat definition, VH comprises the amino acid sequences of CDRs 1, 2, and 3 listed in SEQ ID NOs: 59, 61, and 63, respectively, and VL comprises the amino acid sequences of CDRs 1, 2, and 3 listed in SEQ ID NOs: 64-66, respectively.

[0032] In some embodiments, according to the Chothia definition, VH comprises CDRs 1, 2, and 3 having amino acid sequences listed in SEQ ID NOs: 10, 12, and 13, respectively, and VL comprises CDRs 1, 2, and 3 having amino acid sequences listed in SEQ ID NOs: 14-16, respectively.

[0033] In some embodiments, according to the Chothia definition, VH comprises CDRs 1, 2, and 3 having amino acid sequences listed in SEQ ID NOs: 20, 22, and 23, respectively, and VL comprises CDRs 1, 2, and 3 having amino acid sequences listed in SEQ ID NOs: 24-26, respectively.

[0034] In some embodiments, according to the Chothia definition, the VH comprises the amino acid sequences of CDRs 1, 2, 3 listed in SEQ ID NOs: 40, 42, 43, respectively, and the VL comprises the amino acid sequences of CDRs 1, 2, 3 listed in SEQ ID NOs: 44-46, respectively.

[0035] In some embodiments, according to the Chothia definition, the VH comprises the amino acid sequences of CDRs 1, 2, 3 listed in SEQ ID NOs: 40, 42, 43, respectively, and the VL comprises the amino acid sequences of CDRs 1, 2, 3 listed in SEQ ID NOs: 44-46, respectively.

[0036] In some embodiments, according to the Chothia definition, the VH comprises the amino acid sequences of CDRs 1, 2, 3 listed in SEQ ID NOs: 40, 42, 43, respectively, and the VL comprises the amino acid sequences of CDRs 1, 2, 3 listed in SEQ ID NOs: 44-46, respectively.

[0037] In some embodiments, according to the Chothia definition, the VH comprises the amino acid sequences of CDRs 1, 2, 3 listed in SEQ ID NOs: 40, 42, 43, respectively, and the VL comprises the amino acid sequences of CDRs 1, 2, 3 listed in SEQ ID NOs: 44-46, respectively.

[0038] In some embodiments, the antibody or antigen-binding fragment thereof specifically binds to human, mouse, monkey, or dog CD79b.

[0039] In some embodiments, the antibody or antigen-binding fragment thereof is a humanized antibody or antigen-binding fragment thereof, a single-chain variable fragment (scFv), a one-armed antibody, and / or a multi-specific antibody (e.g., a bi-specific antibody).

[0040] In some embodiments, the antibody or antigen-binding fragment thereof comprises a human IgGl constant region, a human IgG2 constant region, or a human IgG4 constant region.

[0041] In one aspect, the present disclosure relates to a nucleic acid comprising a polynucleotide encoding a polypeptide comprising:

[0042] (1) an immunoglobulin heavy chain or fragment thereof comprising a VH comprising the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 listed in SEQ ID NOs: 9, 11, 13, respectively, and wherein the VH, when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 8, binds CD79b;

[0043] (2) an immunoglobulin light chain or a fragment thereof comprising a VL comprising the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 set forth in SEQ ID NOs: 14-16, respectively, and wherein the VL, when paired with a VH comprising the amino acid sequence of SEQ ID NO: 7, binds CD79b;

[0044] (3) an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 set forth in SEQ ID NOs: 19, 21, 23, respectively, and wherein the VH, when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 18, binds CD79b;

[0045] (4) an immunoglobulin light chain or a fragment thereof comprising a VL comprising the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 set forth in SEQ ID NOs: 24-26, respectively, and wherein the VL, when paired with a VH comprising the amino acid sequence of SEQ ID NO: 17, binds CD79b;

[0046] (5) an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 set forth in SEQ ID NOs: 29, 31, 33, respectively, and wherein the VH, when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 28, binds CD79b;

[0047] (6) an immunoglobulin light chain or a fragment thereof comprising a VL comprising the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 set forth in SEQ ID NOs: 34-36, respectively, and wherein the VL, when paired with a VH comprising the amino acid sequence of SEQ ID NO: 27, binds CD79b;

[0048] (7) an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 set forth in SEQ ID NOs: 39, 41, 43, respectively, and wherein the VH, when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 38, binds CD79b;

[0049] (8) an immunoglobulin light chain or a fragment thereof comprising a VL comprising the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 set forth in SEQ ID NOs: 44-46, respectively, and wherein the VL, when paired with a VH comprising the amino acid sequence of SEQ ID NO: 37, binds CD79b;

[0050] (9) an immunoglobulin heavy chain or a fragment thereof comprising VH, wherein the VH comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 listed in SEQ ID NOs: 49, 51, and 53, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 48;

[0051] (10) an immunoglobulin light chain or a fragment thereof comprising a VL, wherein the VL comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 listed in SEQ ID NOs: 54-56, respectively, and wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence of SEQ ID NO: 47;

[0052] (11) an immunoglobulin heavy chain or a fragment thereof comprising VH, wherein the VH comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 listed in SEQ ID NOs: 59, 61, and 63, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 58;

[0053] (12) an immunoglobulin light chain or a fragment thereof comprising a VL, wherein the VL comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 set forth in SEQ ID NOs: 64-66, respectively, and wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence of SEQ ID NO: 57;

[0054] (13) an immunoglobulin heavy chain or a fragment thereof comprising VH, wherein the VH comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 listed in SEQ ID NOs: 10, 12, and 13, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 8;

[0055] (14) an immunoglobulin heavy chain or a fragment thereof comprising VH, wherein the VH comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 listed in SEQ ID NOs: 20, 22, and 23, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 18;

[0056] (15) an immunoglobulin heavy chain or a fragment thereof comprising VH, wherein the VH comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 listed in SEQ ID NOs: 30, 32, and 33, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 28;

[0057] (16) an immunoglobulin heavy chain or a fragment thereof comprising VH, wherein the VH comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 listed in SEQ ID NOs: 40, 42, and 43, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 38;

[0058] (17) an immunoglobulin heavy chain or a fragment thereof comprising VH, wherein the VH comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 listed in SEQ ID NOs: 50, 52, and 53, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 48;

[0059] (18) an immunoglobulin heavy chain or a fragment thereof comprising VH, wherein the VH comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 listed in SEQ ID NOs: 60, 62, and 63, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 58;

[0060] (19) an immunoglobulin heavy chain or a fragment thereof comprising VH, wherein the VH comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 listed in SEQ ID NOs: 19, 21, and 23, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 70;

[0061] (20) an immunoglobulin light chain or a fragment thereof comprising a VL, wherein the VL comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 listed in SEQ ID NOs: 24-26, respectively, and wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence of SEQ ID NO: 69;

[0062] (21) an immunoglobulin heavy chain or a fragment thereof comprising VH, wherein the VH comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 listed in SEQ ID NOs: 20, 22, and 23, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 70;

[0063] (22) an immunoglobulin heavy chain or a fragment thereof comprising a VH, wherein the VH comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 set forth in SEQ ID NOs: 39, 41, and 43, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 72;

[0064] (23) an immunoglobulin light chain or a fragment thereof comprising a VL, wherein the VL comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 set forth in SEQ ID NOs: 44-46, respectively, and wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence of SEQ ID NO: 71;

[0065] (24) an immunoglobulin heavy chain or a fragment thereof comprising VH, wherein the VH comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 set forth in SEQ ID NOs: 40, 42, and 43, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 72;

[0066] (25) an immunoglobulin heavy chain or a fragment thereof comprising a VH, wherein the VH comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 set forth in SEQ ID NOs: 49, 51, and 53, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 73;

[0067] (26) an immunoglobulin light chain or a fragment thereof comprising a VL, wherein the VL comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 set forth in SEQ ID NOs: 54-56, respectively, and wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence of SEQ ID NO: 74;

[0068] (27) an immunoglobulin heavy chain or a fragment thereof comprising a VH, wherein the VH comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 set forth in SEQ ID NOs: 50, 52, and 53, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 73;

[0069] (28) an immunoglobulin heavy chain or a fragment thereof comprising a VH, wherein the VH comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 set forth in SEQ ID NOs: 59, 61, and 63, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 76;

[0070] (29) an immunoglobulin light chain or a fragment thereof comprising a VL, wherein the VL comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 listed in SEQ ID NOs: 64-66, respectively, and wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence of SEQ ID NO: 75;

[0071] (30) an immunoglobulin heavy chain or a fragment thereof comprising VH, wherein the VH comprises the amino acid sequences of complementarity determining regions (CDRs) 1, 2, and 3 set forth in SEQ ID NOs: 60, 62, and 63, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 76;

[0072] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or a fragment thereof, wherein the polypeptide comprises a VL comprising CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 14-16, respectively.

[0073] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or a fragment thereof, wherein the polypeptide comprises a VL comprising CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 24-26, respectively.

[0074] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or a fragment thereof, wherein the polypeptide comprises a VL of CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 34-36, respectively.

[0075] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or a fragment thereof, wherein the polypeptide comprises a VL of CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 44-46, respectively.

[0076] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or a fragment thereof, wherein the polypeptide comprises a VL comprising CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 54-56, respectively.

[0077] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or a fragment thereof, wherein the polypeptide comprises a VL of CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 64-66, respectively.

[0078] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof, wherein the polypeptide comprises a VH of CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 9, 11, and 13, respectively.

[0079] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof, wherein the polypeptide comprises a VH of CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 19, 21, and 23, respectively.

[0080] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof, wherein the polypeptide comprises a VH of CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 29, 31, and 3, respectively.

[0081] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof, wherein the polypeptide comprises a VH of CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 39, 41, and 43, respectively.

[0082] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof, wherein the polypeptide comprises a VH comprising CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 49, 51, and 53, respectively.

[0083] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof, wherein the polypeptide comprises a VH comprising CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 59, 61, and 63, respectively.

[0084] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof, wherein the polypeptide comprises a VH comprising CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 10, 12, and 13, respectively.

[0085] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof, wherein the polypeptide comprises a VH comprising CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 20, 22, and 23, respectively.

[0086] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof, wherein the polypeptide comprises a VH of CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 30, 32, and 3, respectively.

[0087] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof, wherein the polypeptide comprises a VH of CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 40, 42, and 43, respectively.

[0088] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof, wherein the polypeptide comprises a VH comprising CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 50, 52, and 53, respectively.

[0089] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof, wherein the polypeptide comprises a VH of CDRs 1, 2, and 3, and the amino acid sequences of CDRs 1, 2, and 3 are listed in SEQ ID NOs: 60, 62, and 63, respectively.

[0090] In some embodiments, the VH specifically binds human, mouse, monkey, or dog CD79b when paired with the VL, or the VL specifically binds human, mouse, monkey, or dog CD79b when paired with the VH.

[0091] In some embodiments, the immunoglobulin heavy chain or fragment thereof comprises a human immunoglobulin heavy chain fragment (e.g., human IgG1 heavy chain CH1, CH2 and / or CH3, human IgG2 heavy chain CH1, CH2 and / or CH3, or human IgG4 heavy chain CH1, CH2 and / or CH3), and the immunoglobulin light chain or fragment thereof comprises a human immunoglobulin light chain constant region.

[0092] In some embodiments, the nucleic acid encodes a single-chain variable fragment (scFv), a one-armed antibody, a multispecific antibody (eg, a bispecific antibody), or a chimeric antigen receptor (CAR).

[0093] In some embodiments, the nucleic acid is cDNA.

[0094] In one aspect, the present disclosure relates to vectors comprising one or more nucleic acids described herein.

[0095] In one aspect, the present disclosure relates to a vector comprising two nucleic acids described herein, wherein the vector encodes a VL region and a VH region that together bind CD79b.

[0096] In one aspect, the invention relates to a pair of vectors, wherein each vector comprises one of the nucleic acids described herein, wherein the pair of vectors collectively encode and bind to the VL and VH regions of CD79b.

[0097] In one aspect, the present invention relates to a cell comprising a vector described herein or a vector pair described herein.

[0098] In some embodiments, the cells are CHO cells.

[0099] In one aspect, the present disclosure relates to cells comprising one or more nucleic acids described herein.

[0100] In one aspect, the present disclosure relates to cells comprising two nucleic acids described herein.

[0101] In some embodiments, the two nucleic acids jointly encode and bind to the VL and VH regions of CD79b.

[0102] In one aspect, the present invention relates to a method for producing an antibody or an antigen-binding fragment thereof, the method comprising

[0103] (a) culturing a cell as described herein under conditions sufficient for the cell to produce the antibody or antigen-binding fragment; and

[0104] (b) Collecting the antibodies or antigen-binding fragments produced by the cells.

[0105] In one aspect, the present invention relates to antibodies or antigen-binding fragments thereof that bind to CD79b, comprising

[0106] The heavy chain variable region (VH) comprises an amino acid sequence that is at least 90% identical to a selected VH sequence, and the light chain variable region (VL) comprises an amino acid sequence that is at least 90% identical to a selected VL sequence, wherein the selected VH sequence and the selected VL sequence are one of the following:

[0107] (1) The selected VH sequence is SEQ ID NO: 7, and the selected VL sequence is SEQ ID NO: 8;

[0108] (2) the selected VH sequence is SEQ ID NO: 17 or 69, and the selected VL sequence is SEQ ID NO: 18 or 70;

[0109] (3) The selected VH sequence is SEQ ID NO: 27, and the selected VL sequence is SEQ ID NO: 28;

[0110] (4) the selected VH sequence is SEQ ID NO: 37 or 71, and the selected VL sequence is SEQ ID NO: 38 or 72;

[0111] (5) the selected VH sequence is SEQ ID NO: 47 or 73, and the selected VL sequence is SEQ ID NO: 48 or 74;

[0112] (6) The selected VH sequence is SEQ ID NO: 57 or 75, and the selected VL sequence is SEQ ID NO: 58 or 76.

[0113] In some embodiments, VH comprises the sequence of SEQ ID NO: 7 and VL comprises the sequence of SEQ ID NO: 8.

[0114] In some embodiments, VH comprises the sequence of SEQ ID NO: 17 and VL comprises the sequence of SEQ ID NO: 18.

[0115] In some embodiments, the VH comprises the sequence of SEQ ID NO: 27 and the VL comprises the sequence of SEQ ID NO: 28.

[0116] In some embodiments, the VH comprises the sequence of SEQ ID NO: 37 and the VL comprises the sequence of SEQ ID NO: 38.

[0117] In some embodiments, the VH comprises the sequence of SEQ ID NO: 47 and the VL comprises the sequence of SEQ ID NO: 48.

[0118] In some embodiments, the VH comprises the sequence of SEQ ID NO: 57 and the VL comprises the sequence of SEQ ID NO: 58.

[0119] In some embodiments, the VH comprises the sequence of SEQ ID NO: 69 and the VL comprises the sequence of SEQ ID NO: 70.

[0120] In some embodiments, the VH comprises the sequence of SEQ ID NO: 71 and the VL comprises the sequence of SEQ ID NO: 72.

[0121] In some embodiments, the VH comprises the sequence of SEQ ID NO: 73 and the VL comprises the sequence of SEQ ID NO: 74.

[0122] In some embodiments, the VH comprises the sequence of SEQ ID NO: 75 and the VL comprises the sequence of SEQ ID NO: 76.

[0123] In one aspect, the present disclosure relates to an antibody or antigen-binding fragment thereof that binds CD79b, comprising

[0124] a heavy chain variable region (VH) comprising a VH CDR1, a VH CDR2, and a VH CDR3 that are identical to the VH CDR1, the VH CDR2, and the VH CDR3 of a selected VH sequence; and a light chain variable region (VL) comprising a VL CDR1, a VL CDR2, and a VL CDR3 that are identical to the VL CDR1, the VL CDR2, and the VL CDR3 of a selected VL sequence, wherein the selected VH sequence and the selected VL sequence are one of:

[0125] (1) the selected VH sequence is SEQ ID NO: 7 and the selected VL sequence is SEQ ID NO: 8;

[0126] (2) the selected VH sequence is SEQ ID NO: 17 or 69 and the selected VL sequence is SEQ ID NO: 18 or 70;

[0127] (3) the selected VH sequence is SEQ ID NO: 27 and the selected VL sequence is SEQ ID NO: 28;

[0128] (4) the selected VH sequence is SEQ ID NO: 37 or 71 and the selected VL sequence is SEQ ID NO: 38 or 72;

[0129] (5) the selected VH sequence is SEQ ID NO: 47 or 73 and the selected VL sequence is SEQ ID NO: 48 or 74; and

[0130] (6) the selected VH sequence is SEQ ID NO: 57 or 75 and the selected VL sequence is SEQ ID NO: 58 or 76.

[0131] In some embodiments, the antibody or antigen-binding fragment thereof specifically binds human, mouse, monkey, or dog CD79b.

[0132] In some embodiments, the antibody or antigen-binding fragment thereof is a humanized antibody or antigen-binding fragment thereof, a chimeric antibody, a single chain variable fragment (scFv), a one-armed antibody, and / or a multispecific antibody. In some embodiments, the antibody is a bispecific antibody.

[0133] In some embodiments, the antibody or antigen-binding fragment comprises a human IgGl Fc, a human IgG2 Fc, or a human IgG4 Fc.

[0134] In one aspect, the present disclosure relates to an antibody or antigen-binding fragment thereof that cross-competes with an antibody or antigen-binding fragment thereof described herein.

[0135] In some embodiments, the antibody or antigen-binding fragment thereof comprises a fragment, crystallizable region (Fc region).

[0136] In one aspect, the present disclosure relates to a chimeric antigen receptor (CAR) comprising an antibody or antigen-binding fragment thereof described herein.

[0137] In one aspect, the present disclosure relates to an antibody-drug conjugate comprising an antibody or antigen-binding fragment thereof described herein covalently bound to a therapeutic agent.

[0138] In some embodiments, the therapeutic agent is a cytotoxic or cytostatic agent.

[0139] In one aspect, the present disclosure relates to a method of treating a subject having a cancer, the method comprising administering a therapeutically effective amount of a composition comprising an antibody or antigen-binding fragment thereof described herein, a CAR described herein, or an antibody-drug conjugate described herein to the subject.

[0140] In some embodiments, the cancer is lymphoma, leukemia, breast cancer, gastric cancer, pancreatic cancer, prostate cancer, cervical cancer, endometrial cancer, ovarian cancer, or urothelial cancer.

[0141] In some embodiments, the cancer is non-Hodgkin lymphoma (NHL), diffuse large B-cell lymphoma (DLBCL), B-cell acute lymphoblastic leukemia (B-ALL), chronic lymphocytic leukemia (CLL), B-cell prolymphocytic leukemia (PLL), splenic lymphoma with villous lymphocytes (SLVL), hairy cell leukemia (HCL), follicular lymphoma (FL), or mantle cell (MCL) lymphoma.

[0142] In some embodiments, the subject is further treated with an effective amount of an anti-4-1BB antibody, an anti-OX40 antibody, an anti-PD-1 antibody, an anti-PD-L1 antibody, an anti-CTLA4 antibody, an anti-CD40 antibody, a BTK inhibitor, and a BCL2 inhibitor.

[0143] In one aspect, the present disclosure relates to a method of reducing the growth rate of a tumor, the method comprising contacting a tumor cell with an effective amount of a composition comprising an antibody or antigen-binding fragment thereof described herein, a CAR described herein, or an antibody-drug conjugate described herein.

[0144] In one aspect, the present disclosure relates to a method of killing a tumor cell, the method comprising contacting a tumor cell with an effective amount of a composition comprising an antibody or antigen-binding fragment thereof described herein, a CAR described herein, or an antibody-drug conjugate described herein.

[0145] In one aspect, the present disclosure relates to a method of increasing an immune response in a subject, the method comprising administering to the subject an effective amount of a composition comprising an antibody or antigen-binding fragment thereof described herein, a CAR described herein, or an antibody-drug conjugate described herein.

[0146] In one aspect, the present disclosure relates to a method of treating a subject having an autoimmune disease, the method comprising administering a therapeutically effective amount of a composition comprising an antibody or antigen-binding fragment thereof described herein, a CAR described herein, or an antibody-drug conjugate described herein.

[0147] In some embodiments, the autoimmune disease is selected from rheumatoid arthritis, psoriasis, multiple sclerosis, immune thrombocytopenic purpura, myasthenia gravis, neuromyelitis optica, IgG4-related disease, systemic lupus erythematosus, lupus nephritis, giant cell arteritis, Takayasu's disease, cold agglutinin disease, warm autoimmune hemolytic anemia and antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis with polyangiitis (GPA) (Wegener's granulomatosis) or microscopic polyangiitis (MPA), inflammatory bowel disease (IBD) and autoreactive pancreatitis.

[0148] In some embodiments, the autoimmune disease is multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease (IBD), or autoreactive pancreatitis.

[0149] In one aspect, the present disclosure relates to a pharmaceutical composition comprising an antibody or antigen-binding fragment thereof described herein and a pharmaceutically acceptable carrier.

[0150] In one aspect, the present disclosure relates to a pharmaceutical composition comprising an antibody drug conjugate as described herein and a pharmaceutically acceptable carrier.

[0151] As used herein, the term "cancer" refers to a cell with the ability to grow autonomously. Examples of such cells include cells with an abnormal state or condition characterized by rapidly proliferating cell growth. The term is intended to include cancerous growths, such as tumors; oncogenic processes, metastatic tissues, and malignantly transformed cells, tissues, or organs, regardless of the histopathological type or stage of invasion. The term also includes malignant tumors of various organ systems, such as the respiratory, cardiovascular, renal, reproductive, hematological, nervous, hepatic, gastrointestinal, and endocrine systems; and adenocarcinomas, including malignant tumors such as most colon cancers, renal cell carcinomas, prostate cancers, and / or testicular tumors, non-small cell carcinomas of the lung, and cancer of the small intestine. "Naturally occurring" cancers include any cancer that is not experimentally induced by implanting cancer cells into a subject, including, for example, spontaneously arising cancers, cancers caused by exposure of a patient to a carcinogen, cancers caused by the insertion of a transgenic oncogene or the knockout of a tumor suppressor gene, and cancers caused by infection, such as viral infection. The term "cancer" is recognized in the art and refers to a malignant tumor of epithelial or endocrine tissue. The term also includes carcinosarcoma, which includes malignant tumors composed of cancerous and sarcomatous tissue. "Adenocarcinoma" refers to a cancer that originates from glandular tissue or in which the tumor cells form identifiable glandular structures. The term "sarcoma" is art-recognized and refers to malignant tumors of mesenchymal origin. The term "hematopoietic neoplastic disease" includes diseases involving hyperplastic / neoplastic cells of hematopoietic origin. Hematopoietic neoplastic diseases can arise from cells of the myeloid, lymphoid, or erythroid lineages or their precursors.

[0152] According to usage herein, the term "antibody" refers to any antigen binding molecule comprising at least one (e.g., one, two, three, four, five, or six) complementarity determining region (CDR) (e.g., any of the three CDRs from an immunoglobulin light chain or any of the three CDRs from an immunoglobulin heavy chain) and is capable of specifically binding an epitope. Non-limiting examples of antibodies include: monoclonal antibodies, polyclonal antibodies, multispecific antibodies (e.g., bispecific antibodies), single-chain antibodies, chimeric antibodies, human antibodies, and humanized antibodies. In some embodiments, an antibody can comprise an Fc region of a human antibody. The term antibody also includes derivatives, such as bispecific antibodies, single-chain antibodies, and multispecific antibodies formed from antibody fragments.

[0153] According to usage herein, the term "antigen binding fragment" refers to a portion of a full-length antibody, wherein the portion of the antibody is capable of specifically binding an antigen. In some embodiments, an antigen binding fragment comprises at least one variable domain (e.g., a heavy chain variable domain or a light chain variable domain). Non-limiting examples of antibody fragments include, for example, Fab, Fab', F(ab')2, and Fv fragments.

[0154] According to usage herein, the term "chimeric antibody" refers to an antibody comprising sequences present in at least two different antibodies (e.g., antibodies from two different mammalian species, such as a human antibody and a non-human antibody). A non-limiting example of a chimeric antibody is an antibody comprising variable domain sequences (e.g., all or a portion of the light chain and / or heavy chain variable domain sequences) of a non-human (e.g., mouse, rabbit) antibody and constant domains of a human antibody. Other examples of chimeric antibodies are described herein and are known in the art.

[0155] As used herein, the term "humanized antibody" refers to a non-human antibody that contains minimal sequence derived from a non-human (e.g., mouse, rabbit) immunoglobulin and contains sequence derived from a human immunoglobulin. In a non-limiting example, a humanized antibody is a human antibody (recipient antibody) in which residues from the hypervariable regions (e.g., CDRs) of the recipient antibody are replaced with residues from a non-human antibody (e.g., donor antibody), such as a mouse, rat, or rabbit antibody, with the desired specificity, affinity, and capacity. In some embodiments, Fv framework residues of the human immunoglobulin are replaced with corresponding residues from a non-human (e.g., mouse, rabbit) immunoglobulin. In some embodiments, the humanized antibody may contain residues not found in the recipient antibody or the donor antibody. These modifications can further improve antibody performance. In some embodiments, the humanized antibody contains substantially all of at least one, and typically two, variable domains, in which all or substantially all of the hypervariable loops (CDRs) correspond to those of the non-human (CDR) immunoglobulin, and all or substantially all of the framework regions are those of a human immunoglobulin. Humanized antibodies may also contain at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. Humanized antibodies can be produced using molecular biology methods known in the art. Non-limiting examples of methods for producing humanized antibodies are described herein.

[0156] As used herein, the terms "subject" and "patient" are used interchangeably throughout the specification and describe animals, humans or non-humans, to whom treatment according to the methods of the present invention is provided. The present invention encompasses veterinary and non-veterinary applications. Human patients can be adults or minors (e.g., people under the age of 18). In addition to humans, patients also include, but are not limited to, mice, rats, hamsters, guinea pigs, rabbits, ferrets, cats, dogs, and primates. Patients also include, for example, non-human primates (e.g., monkeys, chimpanzees, gorillas, etc.), rodents (e.g., rats, mice, gerbils, hamsters, ferrets, rabbits), lagomorphs, pigs (e.g., pigs, miniature pigs), equines, canines, felines, bovines, and other domestic, farm, and zoo animals.

[0157] As used herein, the phrases "specifically bind" and "specifically bind" when referring to an antibody mean that the antibody interacts with its target molecule (e.g., CD79b) preferentially over other molecules because the interaction is dependent on a specific structure (i.e., antigenic determinant or epitope) on the target molecule; in other words, the agent recognizes and binds to molecules containing a specific structure, rather than all molecules in general. An antibody that specifically binds to a target molecule may be referred to as a target-specific antibody. For example, an antibody that specifically binds to a CD79b molecule may be referred to as a CD79b-specific antibody or an anti-CD79b antibody.

[0158] As used herein, the terms "polypeptide," "peptide," and "protein" are used interchangeably to refer to amino acid polymers of any length of at least two amino acids.

[0159] As used herein, the terms "polynucleotide," "nucleic acid molecule," and "nucleic acid sequence" are used interchangeably herein to refer to nucleotide polymers of any length of at least two nucleotides, including but not limited to DNA, RNA, DNA / RNA hybrids, and modifications thereof.

[0160] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Methods and materials are described herein for use in the present invention; other suitable methods and materials known in the art can also be used. The materials, methods, and examples are illustrative only and not limiting. All publications, patent applications, patents, sequences, database entries, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control.

[0161] Other features and advantages of the invention will be apparent from the following detailed description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0162] Figure 1 ELISA binding affinity of anti-CD79b antibodies to human CD79b recombinant protein is shown.

[0163] Figure 2 ELISA binding affinity of anti-CD79b antibodies to cynomolgus monkey CD79b recombinant protein is shown.

[0164] Figure 3 BLI binding affinity of anti-CD79b antibodies to human CD79b recombinant protein is shown.

[0165] Figure 4 Relative internalization of anti-CD79b antibody from the cell surface of Ramos cells is shown.

[0166] Figure 5 Quantification of anti-CD79b antigen density on the surface of malignant B tumor cells and normal B cells is shown.

[0167] Figure 6 The binding affinity of anti-CD79b antibodies to BJAB cells is shown.

[0168] Figure 7 The binding affinity of anti-CD79b antibodies to Ramos cells is shown.

[0169] Figure 8 The binding affinity of anti-CD79b antibodies to Daudi cells is shown.

[0170] Figure 9 The binding affinity of anti-CD79b antibodies to SU-DHL-4 cells is shown.

[0171] Figure 10 The binding affinity of anti-CD79b antibodies to Nalm-6 cells is shown.

[0172] Figure 11 The binding affinity of anti-CD79b antibodies to donor 2890 is shown.

[0173] Figure 12 The binding affinity of anti-CD79b antibody to donor 2235 is shown.

[0174] Figure 13 The binding affinity of anti-CD79b antibody to donor 889 is shown.

[0175] Figure 14 The binding affinity of anti-CD79b antibody to donor 356 is shown.

[0176] Figure 15 The binding affinity of anti-CD79b antibodies to CLL donor 5716 is shown.

[0177] Figure 16 Binding affinity of anti-CD79b antibodies to CLL donor 0255 is shown.

[0178] 17A-17B show the binding of anti-CD79b antibodies to the long and short isoforms of CD79b.

[0179] Figure 18 ELISA showing binding of humanized anti-CD79b antibody to recombinant human CD79b ECD.

[0180] Figure 19 Binding of humanized anti-CD79b antibodies to cell lines expressing endogenous CD79b is shown.

[0181] Figure 20 The CDR sequences of anti-CD79b antibodies according to the Kabat definition are listed.

[0182] Figure 21 The CDR sequences of anti-CD79b antibodies according to the Chothia definition are listed.

[0183] Figure 22 The amino acid sequences involved in the present invention are listed. DETAILED DESCRIPTION

[0184] The B-lymphocyte antigen receptor is a multimeric complex that includes an antigen-specific component, the surface immunoglobulin (Ig). The surface immunoglobulin is non-covalently associated with two other proteins, CD79a and CD79b, which are essential for the expression and function of the B-cell antigen receptor. CD79 is the signaling component of the B-cell receptor, functioning as a covalent heterodimer comprising CD79a (i.e., Ig-alpha or MB1) and CD79b (i.e., Ig-beta or B29). CD79b comprises an extracellular immunoglobulin (Ig) domain, a transmembrane domain, and an intracellular signaling domain, an immunoreceptor tyrosine-based activation motif (ITAM) domain. CD79b expression is detected on the surface of almost all non-Hodgkin's lymphomas (NHL), acute lymphoblastic leukemia (ALL), and chronic lymphocytic leukemia (CLL) patients.

[0185] The present summary provides examples of antibodies and antigen-binding fragments thereof that bind CD79b.

[0186] CD79b

[0187] CD79 is composed of CD79a and CD79b components that are expressed almost exclusively on B cells and B cell tumors. CD79a and CD79b expression precede immunoglobulin (Ig) heavy chain gene rearrangement and CD20 expression during B cell ontogeny, and CD20 disappears late in the terminal (plasma cell) stage of B cell differentiation. Thus, antibodies to CD79a and CD79b are useful in the differential diagnosis of B cell tumors from T cell tumors or myeloid tumors, or L and H lymphocyte predominant Hodgkin's lymphoma from classical Hodgkin's lymphoma. In addition, anti-CD79a and anti-CD79b antibodies are useful markers in the diagnosis of pre-B-ALL, as many of these tumors are negative for other B cell markers such as CD20 and CD45RA.

[0188] CD79 is considered an interesting therapeutic target for antibodies because it is physiologically and specifically expressed on mature B cells and the vast majority of B cell NHLs, including DLBCL (from 90% to 100%), as well as B-ALL, CLL, B cell prolymphocytic leukemia (PLL), splenic lymphoma with villous lymphocytes (SLVL), hairy cell leukemia (HCL), follicular lymphoma (FL), and mantle cell lymphoma (MCL) lymphomas.

[0189] CD79 binds to cell surface immunoglobulin (sIg) for antigen recognition, constituting the B cell antigen receptor (BCR) complex, playing a key role in B cell maturation and activation. CD79 is composed of an a (CD79a) and b (CD79b) heterodimer, whose function is the signal transduction component of the BCR. Both subunits of CD79 contain an extracellular Ig domain, a transmembrane domain, and an intracellular signaling domain, which upon antigen binding initiates BCR signaling, ultimately leading to B cell activation, antigen presentation, cytokine production, and cell proliferation and differentiation.

[0190] Antigen binding of the BCR induces its internalization and processing to the major histocompatibility complex class II (MHCII) compartment, a lysosome-like compartment, for class II antigen presentation by B cells. This intracellular trafficking is of particular interest because it allows direct delivery of drugs to target cells into the lysosomal compartment, enhancing cytotoxic activity, and it allows the use of more stable linkers that are cleaved in the MHCII compartment.

[0191] Detailed reviews of CD79b and its function can be found in Chu, Peiguo G., and Daniel A. Arber. "CD79: a review." Applied Immunohistochemistry & Molecular Morphology 9.2 (2001): 97-106; Bourbon, Estelle, and Gilles Salles. "Polatuzumab vedotin: an investigational anti-CD79b antibody drug conjugate for the treatment of diffuse large B-cell lymphoma." Expert Opinion on Investigational Drugs 29.10 (2020): 1079-1088, each of which is incorporated by reference in its entirety.

[0192] The present summary provides several anti-CD79b antibodies, antigen-binding fragments thereof, and methods of using these anti-CD79b antibodies and antigen-binding fragments to inhibit tumor growth, treat cancer, and treat autoimmune diseases.

[0193] Antibodies and antigen-binding fragments

[0194] The present summary provides anti-CD79b antibodies and antigen-binding fragments thereof. Generally, an antibody (also referred to as an immunoglobulin) is composed of two classes of polypeptide chains, light and heavy. Non-limiting antibodies of the present summary can be intact four immunoglobulin chain antibodies comprising two heavy chains and two light chains. The heavy chain of an antibody can be of any isotype, including IgM, IgG, IgE, IgA, or IgD, or an isotype subtype, including IgGl, IgG2, IgG2a, IgG2b, IgG3, IgG4, IgEl, IgE2, etc. The light chain can be a kappa light chain or a lambda light chain. An antibody can comprise two identical copies of a light chain and two identical copies of a heavy chain. Each heavy chain comprises a variable domain (or variable region, VH) and multiple constant domains (or constant regions), which associate with each other through disulfide bonds within their constant domains to form the "backbone" of the antibody. Each light chain comprises a variable domain (or variable region, VL) and a constant domain (or constant region), each of which binds to a heavy chain through a disulfide bond. The variable region of each light chain aligns with the variable region of the heavy chain to which it binds. The variable regions of the light and heavy chains comprise three hypervariable regions, sandwiched between more conserved framework regions (FRs).

[0195] These hypervariable regions, known as complementarity determining regions (CDRs), form loops that make up the main antigen-binding surface of the antibody. The four framework regions primarily adopt a beta sheet conformation, with the CDRs forming loops connecting the beta sheet structure and, in some cases, forming part of the beta sheet structure. The CDRs in each chain are in close proximity to the framework regions and, together with the CDRs in the other chain, contribute to the formation of the antigen-binding region.

[0196] Methods for identifying the CDR regions of antibodies by analyzing their amino acid sequences are well known, and various definitions of CDRs are commonly used: the Kabat definition is based on sequence variability, while the Chothia definition is based on the location of structural loop regions. These methods and definitions are in Martin, "Protein sequence and structure analysis ofantibody variable domains," Antibody engineering, Springer Berlin Heidelberg, 2001. 422-439; Abhinandan, et al. (1970) J. Exp. Med. 132: 211-250; Martin et al., Methods Enzymol. 203:121-53 (1991); Morea et al., Biophys Chem. 68(1-3):9-16 (Oct. 1997); Morea et al., J Mol Biol. 275(2):269-94 (Jan .1998); Chothia et al. al., Nature 342(6252):877-83 (Dec. 1989); Ponomarenko and Bourne, BMC Structural Biology 7:64 (2007), each of which is incorporated herein by reference in its entirety.

[0197] CDRs are important for recognizing antigenic epitopes. As used herein, an "epitope" is the smallest portion of a target molecule that can be specifically bound by the antigen-binding domain of an antibody. The minimum number of an epitope can be about three, four, five, six, or seven amino acids, but these amino acids do not need to be located in a continuous linear sequence within the primary structure of the antigen, as the epitope may depend on the three-dimensional configuration of the antigen based on its secondary and tertiary structures.

[0198] In some embodiments, the antibody is an intact immunoglobulin molecule (e.g., IgGl, IgG2a, IgG2b, IgG3, IgM, IgD, IgE, IgA). The IgG subclasses (IgGl, IgG2, IgG3, and IgG4) are highly conserved, their constant regions differ, especially the hinge and upper CH2 domains. The sequences and differences of the IgG subclasses are known in the art and described in Vidarsson, et al, IgG subclasses and allotypes: from structure to effector functions. Frontiers in immunology 5 (2014); Irani, et al. Molecular properties of human IgG subclasses and their implications for designing therapeutic monoclonal antibodies against infectious diseases. Molecular immunology 67.2 (2015): 171-182; Shakib, Farouk, ed. The human IgG subclasses: molecular analysis of structure, function and regulation. Elsevier, 2016; each of which is incorporated by reference herein in its entirety.

[0199] The antibody may also be an immunoglobulin molecule derived from any species (e.g., human, rodent, mouse, camel, rabbit). The antibodies disclosed herein also include, but are not limited to, polyclonal antibodies, monoclonal antibodies, monospecific antibodies, multispecific antibodies, and chimeric antibodies, which include an immunoglobulin binding domain fused to another polypeptide. The term "antigen-binding domain" or "antigen-binding fragment" is a part of an antibody that retains the specific binding activity of an intact antibody, i.e., any part of an antibody that is capable of specifically binding to an epitope on an intact antibody target molecule. It includes, for example, Fab, Fab', F(ab')2, and variants of these fragments. Therefore, in some embodiments, an antibody or its antigen-binding fragment may be, for example, a single-chain antibody, Fv, Fd, a bispecific antibody, a single-chain antibody molecule, a multispecific antibody formed by an antibody fragment, and any polypeptide comprising a binding domain homologous to an antibody binding domain or to an antibody binding domain. Non-limiting examples of antigen binding domains include, e.g., the heavy and / or light chain CDRs of an intact antibody, the heavy and / or light chain variable regions of an intact antibody, the full length heavy or light chain of an intact antibody, or a single CDR within the heavy or light chain of an intact antibody.

[0200] In some embodiments, the antigen binding fragment may form part of a chimeric antigen receptor (CAR). In some embodiments, the scFv has one heavy chain variable domain and one light chain variable domain. In some embodiments, the scFv has two heavy chain variable domains and two light chain variable domains.

[0201] Anti-CD79b antibodies and antigen-binding fragments

[0202] The present invention provides antibodies and antigen-binding fragments thereof that specifically bind to CD79b (e.g., human CD79b). The antibodies and antigen-binding fragments described herein are capable of binding to CD79b. These antibodies can be agonists or antagonists of CD79b-mediated BCR signaling. In some embodiments, the antibodies and antigen-binding fragments can bind to the extracellular domain of human CD79b.

[0203] The present invention provides, for example, anti-CD79b antibodies 22D10, 23D8, 29C3, 44G2, 48H10, 57B9, chimeric antibodies thereof, and humanized antibodies thereof.

[0204] According to the Kabat definition, the CDR sequences of 22D10 and 22D10- derived antibodies (e.g., humanized antibodies) include the CDR amino acid sequences of the heavy chain variable region set forth in SEQ ID NOs: 9, 11, 13, and the CDR amino acid sequences of the light chain variable region set forth in SEQ ID NOs: 14-16. The CDRs can also be defined by Chothia. According to the Chothia definition, the CDR amino acid sequences of the heavy chain variable region are set forth in SEQ ID NOs: 10, 12, 13, and the CDR amino acid sequences of the light chain variable region are set forth in SEQ ID NOs: 14-16.

[0205] Similarly, according to the Kabat definition, the CDR sequences of 23D8 and 23D8- derived antibodies include the CDR amino acid sequences of the heavy chain variable region set forth in SEQ ID NOs: 19, 21, 23, and the CDR amino acid sequences of the light chain variable region set forth in SEQ ID NOs: 24-26. According to the Chothia definition, the CDR amino acid sequences of the heavy chain variable region are set forth in SEQ ID NOs: 20, 22, 23, and the CDR amino acid sequences of the light chain variable region are set forth in SEQ ID NOs: 24-26.

[0206] According to the Kabat definition, the CDR sequences of 29C3 and 29C3- derived antibodies include the CDR amino acid sequences of the heavy chain variable region set forth in SEQ ID NOs: 29, 31, 33, and the CDR amino acid sequences of the light chain variable region set forth in SEQ ID NOs: 34-36. According to the Chothia definition, the CDR amino acid sequences of the heavy chain variable region are set forth in SEQ ID NOs: 30, 32, 33, and the CDR amino acid sequences of the light chain variable region are set forth in SEQ ID NOs: 34-36.

[0207] According to the Kabat definition, the CDR sequences of 44G2 and 44G2- derived antibodies include the CDR amino acid sequences of the heavy chain variable region set forth in SEQ ID NOs: 39, 41, 43, and the CDR amino acid sequences of the light chain variable region set forth in SEQ ID NOs: 44-46. According to the Chothia definition, the CDR amino acid sequences of the heavy chain variable region are set forth in SEQ ID NOs: 40, 42, 43, and the CDR amino acid sequences of the light chain variable region are set forth in SEQ ID NOs: 44-46.

[0208] According to the Kabat definition, the CDR sequences of 48H10 and 48H10-derived antibodies include the heavy chain variable region CDR amino acid sequences listed in SEQ ID NOs: 49, 51, and 53, and the light chain variable region CDR amino acid sequences listed in SEQ ID NOs: 54 to 56. According to the Chothia definition, the heavy chain variable region CDR amino acid sequences are listed in SEQ ID NOs: 50, 52, and 53, and the light chain variable region CDR amino acid sequences are listed in SEQ ID NOs: 54 to 56.

[0209] According to the Kabat definition, the CDR sequences of 57B9 and 57B9-derived antibodies, including the heavy chain variable region CDR amino acids listed in SEQ ID NOs: 59, 61, and 63, and the light chain variable region CDR amino acids listed in SEQ ID NOs: 64 to 66. According to the Chothia definition, the heavy chain variable region CDR amino acid sequences are listed in SEQ ID NOs: 60, 62, and 63, and the light chain variable region CDR amino acid sequences are listed in SEQ ID NOs: 64 to 66.

[0210] The amino acid sequence of the heavy chain variable region of the 22D10 antibody is set forth in SEQ ID NO: 7. The amino acid sequence of the light chain variable region of the 22D10 antibody is set forth in SEQ ID NO: 8.

[0211] The amino acid sequence of the heavy chain variable region of the 23D8 antibody is set forth in SEQ ID NO: 17. The amino acid sequence of the light chain variable region of the 23D8 antibody is set forth in SEQ ID NO: 18.

[0212] The amino acid sequence of the heavy chain variable region of the 29C3 antibody is set forth in SEQ ID NO: 27. The amino acid sequence of the light chain variable region of the 29C3 antibody is set forth in SEQ ID NO: 28.

[0213] The amino acid sequence of the heavy chain variable region of the 44G2 antibody is set forth in SEQ ID NO: 37. The amino acid sequence of the light chain variable region of the 44G2 antibody is set forth in SEQ ID NO: 38.

[0214] The amino acid sequence of the heavy chain variable region of the 48H10 antibody is set forth in SEQ ID NO: 47. The amino acid sequence of the light chain variable region of the 48H10 antibody is set forth in SEQ ID NO: 48.

[0215] The amino acid sequence of the heavy chain variable region of the 57B9 antibody is set forth in SEQ ID NO: 57. The amino acid sequence of the light chain variable region of the 57B9 antibody is set forth in SEQ ID NO: 58.

[0216] In some embodiments, the anti-CD79b antibody is a humanized antibody. In some embodiments, the anti-CD79b antibody is a humanized 23D8, 44G2, 48H10, or 57B9.

[0217] The amino acid sequence of the heavy chain variable region of the humanized 23D8 antibody is set forth in SEQ ID NO: 69. The amino acid sequence of the light chain variable region of the 23D8 antibody is set forth in SEQ ID NO: 70.

[0218] The amino acid sequence of the heavy chain variable region of the humanized 44G2 antibody is set forth in SEQ ID NO: 71. The amino acid sequence of the light chain variable region of the 44G2 antibody is set forth in SEQ ID NO: 72.

[0219] The amino acid sequence of the heavy chain variable region of the humanized 48H10 antibody is set forth in SEQ ID NO: 73. The amino acid sequence of the light chain variable region of the 48H10 antibody is set forth in SEQ ID NO: 74.

[0220] The amino acid sequence of the heavy chain variable region of the humanized 57B9 antibody is set forth in SEQ ID NO: 75. The amino acid sequence of the light chain variable region of the 57B9 antibody is set forth in SEQ ID NO: 76.

[0221] Amino acid sequences of the heavy chain variable region and the light chain variable region of the modified antibodies are also provided. In some embodiments, the heavy chain variable region is at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to any one of SEQ ID NOs: 7, 17, 27, 37, 47, and 57. In some embodiments, the light chain variable region is at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to any one of SEQ ID NOs: 8, 18, 28, 38, 48, and 58. The heavy chain variable region sequence can be paired with a corresponding light chain variable region sequence and bind together to CD79b.

[0222] The humanization percentage refers to the percentage of identity of the heavy chain or light chain variable region sequence compared to the human antibody sequence in the International Immunogenetics Information System (IMGT) database. In certain embodiments, the humanization percentage is greater than 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% or 95%. Detailed descriptions of how to determine the humanization percentage and how to determine hotspot hits are known in the art and are described in Jones, et al. The INNs and outs of antibody nonproprietary names. MAbs. Vol. 8. No. 1. Taylor & Francis, 2016, which is incorporated herein by reference in its entirety. High humanization percentages generally have various advantages, for example, being safer and more effective for humans, more likely to be tolerated by human subjects, and / or less likely to produce side effects. In some embodiments, the variable region is fully human, e.g., derived from a human heavy chain immunoglobulin locus sequence (e.g., a recombination of human IGHV, human IGHD, and human IGHJ genes) and / or a human kappa chain immunoglobulin locus sequence (e.g., a recombination of human IGKV and human IGKJ genes).

[0223] In addition, in some embodiments, the antibodies or antigen-binding fragments thereof described herein may further contain one, two or three heavy chain variable region CDRs selected from SEQ ID NOs: 9, 11, 13; SEQ ID NOs: 19, 21, 23; SEQ ID NOs: 29, 31, 33; SEQ ID NOs: 39, 41, 43; SEQ ID NOs: 49, 51, 53; SEQ ID NOs: 59, 61, 63; SEQ ID NOs: 10, 12, 13; SEQ ID NOs: 20, 22, 23; SEQ ID NOs: 30, 32, 33; SEQ ID NOs: 40, 42, 43; SEQ ID NOs: 50, 52, 53; SEQ ID NOs: 60, 62, 63, and / or a heavy chain variable region CDR selected from SEQ ID NOs: 14-16, SEQ ID NOs: 24-26, SEQ ID NOs: 34-36, SEQs ID NOs: 44-46, SEQs ID NOs: 54-56 and SEQ ID One, two or three light chain variable region CDRs of NOs: 64-66.

[0224] In some embodiments, an antibody can have a heavy chain variable region (VH) comprising complementarity determining regions (CDRs) 1, 2, 3, wherein the CDR1 region comprises or consists of an amino acid sequence that is at least 80%, 85%, 90%, or 95% identical to a selected VH CDR1 amino acid sequence, the CDR2 region comprises or consists of an amino acid sequence that is at least 80%, 85%, 90%, or 95% identical to a selected VH CDR2 amino acid sequence, and the CDR3 region comprises or consists of an amino acid sequence that is at least 80%, 85%, 90%, or 95% identical to a selected VH CDR3 amino acid sequence. In some embodiments, an antibody can have a light chain variable region (VL) comprising complementarity determining regions (CDRs) 1, 2, 3, wherein the CDR1 region comprises or consists of an amino acid sequence that is at least 80%, 85%, 90%, or 95% identical to a selected VL CDR1 amino acid sequence, the CDR2 region comprises or consists of an amino acid sequence that is at least 80%, 85%, 90%, or 95% identical to a selected VL CDR2 amino acid sequence, and the CDR3 region comprises or consists of an amino acid sequence that is at least 80%, 85%, 90%, or 95% identical to a selected VL CDR3 amino acid sequence. Figure 20 (Kabat CDR) and Figure 21 (Chothia CDR) show the selected VH CDR 1, 2, 3 amino acid sequences and the selected VL CDR 1, 2, 3 amino acid sequences.

[0225] In some embodiments, an antibody or antigen-binding fragment described herein can have a heavy chain variable region comprising one, two, or three CDRs of SEQ ID NO: 9 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 11 with zero, one, or two amino acid insertions, deletions, or substitutions; or SEQ ID NO: 13 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0226] In some embodiments, an antibody or antigen-binding fragment described herein can have a heavy chain variable region comprising one, two, or three CDRs of SEQ ID NO: 19 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 21 with zero, one, or two amino acid insertions, deletions, or substitutions; or SEQ ID NO: 23 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0227] In some embodiments, an antibody or antigen-binding fragment described herein can contain a heavy chain variable region containing one, two, or three CDRs of SEQ ID NO: 29 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 31 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 33 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0228] In some embodiments, an antibody or antigen-binding fragment described herein can contain a heavy chain variable region containing one, two, or three CDRs of SEQ ID NO: 39 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 41 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 43 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0229] In some embodiments, an antibody or antigen-binding fragment described herein can contain a heavy chain variable region containing one, two, or three CDRs of SEQ ID NO: 49 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 51 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 53 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0230] In some embodiments, an antibody or antigen-binding fragment described herein can contain a heavy chain variable region containing one, two, or three CDRs of SEQ ID NO: 59 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 61 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 63 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0231] In some embodiments, an antibody or antigen-binding fragment described herein can contain a heavy chain variable region containing one, two, or three CDRs of SEQ ID NO: 10 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 12 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 13 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0232] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable region comprising one, two, or three CDRs of SEQ ID NO: 20 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 22 with zero, one, or two amino acid insertions, deletions, or substitutions; or SEQ ID NO: 23 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0233] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable region comprising one, two, or three CDRs of SEQ ID NO: 30 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 32 with zero, one, or two amino acid insertions, deletions, or substitutions; or SEQ ID NO: 33 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0234] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable region comprising one, two, or three CDRs of SEQ ID NO: 40 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 42 with zero, one, or two amino acid insertions, deletions, or substitutions; or SEQ ID NO: 43 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0235] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable region comprising one, two, or three CDRs of SEQ ID NO: 50 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 52 with zero, one, or two amino acid insertions, deletions, or substitutions; or SEQ ID NO: 53 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0236] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable region comprising one, two, or three CDRs of SEQ ID NO: 60 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 62 with zero, one, or two amino acid insertions, deletions, or substitutions; or SEQ ID NO: 63 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0237] In some embodiments, an antibody or antigen-binding fragment described herein can contain a heavy chain variable region containing one, two, or three CDRs of SEQ ID NO: 1; SEQ ID NO: 2; SEQ ID NO: 3; with zero, one, or two amino acid insertions, deletions, or substitutions.

[0238] In some embodiments, an antibody or antigen-binding fragment described herein can contain a heavy chain variable region containing one, two, or three CDRs of SEQ ID NO: 21; SEQ ID NO: 22; SEQ ID NO: 23; with zero, one, or two amino acid insertions, deletions, or substitutions.

[0239] In some embodiments, an antibody or antigen-binding fragment described herein can contain a heavy chain variable region containing one, two, or three CDRs of SEQ ID NO: 31; SEQ ID NO: 32; SEQ ID NO: 33; with zero, one, or two amino acid insertions, deletions, or substitutions.

[0240] In some embodiments, an antibody or antigen-binding fragment described herein can contain a heavy chain variable region containing one, two, or three CDRs of SEQ ID NO: 41; SEQ ID NO: 42; SEQ ID NO: 43; with zero, one, or two amino acid insertions, deletions, or substitutions.

[0241] In some embodiments, an antibody or antigen-binding fragment described herein can contain a heavy chain variable region containing one, two, or three CDRs of SEQ ID NO: 51; SEQ ID NO: 52; SEQ ID NO: 53; with zero, one, or two amino acid insertions, deletions, or substitutions.

[0242] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a light chain variable region comprising one, two, or three CDRs, SEQ ID NO: 64 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 65 with zero, one, or two amino acid insertions, deletions, or substitutions; or SEQ ID NO: 66 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0243] Insertions, deletions, and substitutions can be within a CDR sequence, or at one or both ends of a CDR sequence. In certain embodiments, CDRs are determined based on the Kabat definition. In certain embodiments, CDRs are determined based on the Chothia definition. In certain embodiments, CDRs are determined based on a combination of the Kabat definition and the Chothia definition.

[0244] The present invention also provides antibodies or antigen-binding fragments thereof that bind to CD79b. The antibodies or antigen-binding fragments thereof contain a heavy chain variable region (VH) comprising or consisting of an amino acid sequence at least 80%, 85%, 90% or 95% identical to a selected VH sequence, and a light chain variable region (VL) comprising or consisting of an amino acid sequence at least 80%, 85%, 90% or 95% identical to a selected VL sequence. In some embodiments, the selected VH sequence is SEQ ID NO: 7 and the selected VL sequence is SEQ ID NO: 8. In some embodiments, the selected VH sequence is SEQ ID NO: 17 and the selected VL sequence is SEQ ID NO: 18. In some embodiments, the selected VH sequence is SEQ ID NO: 27 and the selected VL sequence is SEQ ID NO: 28. In some embodiments, the selected VH sequence is SEQ ID NO: 37 and the selected VL sequence is SEQ ID NO: 38. In some embodiments, the selected VH sequence is SEQ ID NO: 47 and the selected VL sequence is SEQ ID NO: 48. In some embodiments, the selected VH sequence is SEQ ID NO: 57 and the selected VL sequence is SEQ ID NO: 58. In some embodiments, the selected VH sequence is SEQ ID NO: 69 and the selected VL sequence is SEQ ID NO: 70. In some embodiments, the selected VH sequence is SEQ ID NO: 71 and the selected VL sequence is SEQ ID NO: 72. In some embodiments, the selected VH sequence is SEQ ID NO: 73 and the selected VL sequence is SEQ ID NO: 74. In some embodiments, the selected VH sequence is SEQ ID NO: 75 and the selected VL sequence is SEQ ID NO: 76.

[0245] The present disclosure also provides antibodies or antigen-binding fragments thereof that can compete with the antibodies described herein.In some aspects, the antibodies or antigen-binding fragments can bind to the same epitope as the antibodies described herein.

[0246] The present disclosure also provides antibodies or antigen-binding fragments thereof that cross-compete with any of the antibodies or antigen-binding fragments described herein. Cross-competition assays are known in the art and described in Moore et al., "Antibody cross-competition analysis of the human immunodeficiency virus type 1 gp120 exterior envelope glycoprotein." Journal of virology 70.3 (1996): 1863-1872, which is incorporated by reference herein in its entirety. In one aspect, the present disclosure also provides antibodies or antigen-binding fragments thereof that bind to the same epitope or region as any of the antibodies or antigen-binding fragments described herein. Epitope binning assays are known in the art and described in Estep et al. "High throughput solution-based measurement of antibody-antigen affinity and epitope binning." MAbs. Vol. 5. No. 2. Taylor & Francis, 2013, which is incorporated by reference herein in its entirety.

[0247] To determine the percent identity of two amino acid sequences or two nucleic acid sequences, the sequences are aligned for optimal comparison purposes (e.g., gaps can be introduced in one or both of a first and a second amino acid or nucleic acid sequence for comparison purposes, default parameters can be used for the alignment, and non-homologous sequences can be ignored). The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules are identical at that position. The percent identity between the two sequences is a function of the number of identical positions shared by the sequences, taking into account the number of gaps, and the length of each gap, which need to be introduced for optimal alignment of the two sequences. The comparison of sequences and determination of percent identity between two sequences can be accomplished using, for example, a Blossum 62 scoring matrix, a gap penalty of 12, a gap extension penalty of 4, and a frameshift gap penalty of 5.

[0248] The present disclosure also provides nucleic acids comprising a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or an immunoglobulin light chain. The immunoglobulin heavy chain or the immunoglobulin light chain comprises CDRs as set forth in SEQ ID NOs: Figure 20 or 21, or as set forth in SEQ ID NOs: Figure 22When the polypeptide is paired with a corresponding polypeptide (eg, a corresponding heavy chain variable region or a corresponding light chain variable region), the paired polypeptide binds to CD79b (eg, human CD79b).

[0249] Anti-CD79b antibodies and antigen-binding fragments can also be antibody variants (including derivatives and conjugates) of antibodies or antibody fragments, as well as multispecific (e.g., bispecific) antibodies or antibody fragments. Other antibodies provided herein are polyclonal, monoclonal, multimeric, multispecific (e.g., bispecific), humanized antibodies, chimeric antibodies (e.g., human-mouse chimeras), single-chain antibodies, antibodies produced intracellularly (i.e., intrabodies), and antigen-binding fragments thereof. The antibody or its antigen-binding fragment can be of any type (e.g., IgG, IgE, IgM, IgD, IgA, and IgY), class (e.g., IgG1, IgG2, IgG3, IgG4, IgA1, and IgA2), or subclass. In some embodiments, the antibody or its antigen-binding fragment is an IgG antibody or its antigen-binding fragment.

[0250] Antibody fragments are suitable for use in the provided methods as long as they retain the desired affinity and specificity of full-length antibodies. Thus, an antibody fragment that binds CD79b will retain the ability to bind CD79b. An Fv fragment is an antibody fragment that contains a complete antigen recognition and binding site. This region consists of a dimer of one heavy-chain variable region and one light-chain variable region in tight association, which can be covalent in nature, as in an scFv. It is in this configuration that the three CDRs of each variable region interact to define the antigen-binding site on the surface of the VH-VL dimer. Collectively, the six CDRs, or a subset thereof, confer antigen-binding specificity to an antibody. However, even a single variable region (or half of an Fv containing only three CDRs specific for an antigen) can have the ability to recognize and bind antigen, although the affinity is generally lower than that of the entire binding site.

[0251] Single-chain Fv or (scFv) antibody fragments contain the VH and VL domains (or regions) of an antibody, wherein these domains are present in a single polypeptide chain. Typically, scFv polypeptides also include a polypeptide linker between the VH and VL domains, which enables the scFv to form the required structure for antigen binding.

[0252] A Fab fragment contains the variable and constant domains of the light chain and the variable and first constant domain (CH1) of the heavy chain. A F(ab')2 antibody fragment comprises a pair of Fab fragments, typically covalently linked near their carboxyl termini via a hinge cysteine ​​residue. Other chemical couplings of antibody fragments are also known in the art.

[0253] The antibodies and antibody fragments of the present application can be modified in the Fc region to provide a desired effector function or serum half-life. In some embodiments, the Fc region can be modified to silence or reduce complement-dependent cytotoxicity (CDC) or antibody-dependent cellular cytotoxicity (ADCC).

[0254] In some embodiments, the multispecific antibody is a bispecific antibody. Bispecific antibodies can be produced by the design of the interface between a pair of antibody molecules to maximize the recovery of the heterodimer from recombinant cell culture. For example, the interface can comprise at least a portion of the CH3 domain of an antibody constant domain. In this approach, one or more small amino acid side chains from the interface of the first antibody molecule are replaced with bulkier side chains (e.g., tyrosine or tryptophan). Compensatory "cavities" of identical or similar bulk are created on the interface of the second antibody molecule by replacing large amino acid side chains with smaller ones (e.g., alanine or threonine). This provides a mechanism for increasing the yield of the heterodimer over other unwanted side products, such as homodimers. This approach is described in, for example, WO96 / 27011, which is incorporated herein by reference in its entirety.

[0255] Any of the antibodies or antigen-binding fragments described herein can be conjugated to a stabilizing molecule (e.g., a molecule that increases the half-life of the antibody or antigen-binding fragment thereof in a subject or in solution). Non-limiting examples of stabilizing molecules include: a polymer (e.g., polyethylene glycol) or a protein (e.g., a serum albumin, such as human serum albumin). Conjugation of a stabilizing molecule can increase the half-life or prolong the biological activity of the antibody or antigen-binding fragment in vitro (e.g., in tissue culture or when stored as a pharmaceutical composition) or in vivo (e.g., in a human)

[0256] In some embodiments, the antibodies or antigen-binding fragments described herein can be conjugated to a therapeutic agent. The antibody-drug conjugate comprising the antibody or antigen-binding fragment thereof can covalently or non-covalently bind the therapeutic agent. In some embodiments, the therapeutic agent is a cytotoxic or cytostatic agent (e.g., cytochalasin B, gramicidin D, ethidium bromide, emetine, mitomycin, etoposide, teniposide, vincristine, vinblastine, colchicin, doxorubicin, daunorubicin, dihydroxy anthracin, maytansinoid, e.g., DM-1 and DM-4, dinitrogen, mitoxantrone, mithramycin, actinomycin D, 1-dehydrotestosterone, glucocorticoid, procaine, tetracaine, lidocaine, propranolol, puromycin, epirubicin, and cyclophosphamide, and the like).

[0257] In some embodiments, the antibodies or antigen-binding fragments thereof described herein recognize endogenous CD79b or recombinant CD79b. In some embodiments, the antibodies or antigen-binding fragments thereof described herein recognize human CD79b (e.g., an extracellular region of human CD79b).

[0258] Antibody drug conjugates (ADCs)

[0259] The antibodies, antigen-binding fragments thereof, or antigen-binding protein constructs (e.g., bispecific antibodies) described herein can be conjugated to a therapeutic agent (drug). The therapeutic agent can be covalently or non-covalently bound to the antibody or antigen-binding fragment or antigen-binding protein construct (e.g., bispecific antibody).

[0260] In some embodiments, the therapeutic agent is a cytotoxic or cytostatic agent (e.g., monomethyl auristatin E, monomethyl auristatin F, cytochalasin B, gramicidin D, ethidium bromide, emetine, mitomycin, etoposide, teniposide, vincristine, vinblastine, colchicin, doxorubicin, daunorubicin, dihydroxy anthracin, maytansinoid such as DM-1 and DM-4, dinitrogen, mitoxantrone, actinomycin, 1-dehydrotestosterone, glucocorticoids, procaine, tetracaine, lidocaine, propranolol, puromycin, epirubicin, and cyclophosphamide and analogs). Useful cytotoxic, cytostatic, or immunomodulatory agents include, for example, anti-tubulin agents, DNA minor groove binding agents, DNA replication inhibitors, and alkylating agents.

[0261] In some embodiments, the therapeutic agent can include, but is not limited to, a cytotoxic agent, such as a chemotherapeutic agent, an immunotherapeutic agent, and the like, an antiviral agent, or an antimicrobial agent. In some embodiments, the therapeutic agent to be conjugated can be selected from, but is not limited to, MMAE (monomethyl auristatin E), MMAD (monomethyl auristatin D), or MMAF (monomethyl auristatin F).

[0262] In some embodiments, the therapeutic agent is an auristatin, such as a derivative of auristatin E (also known in the art as dolastatin-10), or a derivative thereof. The auristatin can be, for example, an ester formed between auristatin E and a ketoacid. For example, auristatin E can react with p-acetylbenzoic acid or benzoylvaleric acid to produce AEB and AEVB, respectively. Other exemplary auristatins include AFP, MMAF, and MMAE. The synthesis and structure of exemplary auristatins are described in U.S. Patent Application Publication No. 2003-0083263; International Patent Publication No. WO 04 / 010957, International Patent Publication No. WO 02 / 088172, and U.S. Patent No. 5,990,910. Nos. 7,498,298; 6,884,869; 6,323,315; 6,239,104; 6,034,065; 5,780,588; 5,665,860; 5,663,149; 5,635,483; 5,599,902; 5,554,725; 5,530,097; 5,521,284; 5,504,191; 5,410,024; 5,138,036; 5,076,973; 4,986,988; 4,978,744; 4,879,278; 4,816,444; 4,486,414 and 4,486,414, each of which is incorporated herein by reference in its entirety for all purposes.

[0263] Auristatins have been shown to interfere with microtubule dynamics, nuclear division, and cell division, and have anticancer activity. Auristatins bind to tubulin and can exert cytotoxic or cytostatic effects on cancer cells. A variety of assays are known in the art that can be used to determine whether an auristatin or resulting antibody-drug conjugate exerts a cytostatic or cytotoxic effect on the desired cells.

[0264] In some embodiments, the therapeutic agent is a chemotherapeutic agent. Examples of chemotherapeutic agents include alkylating agents, such as thiotepa and cyclophosphamide (CYTOXAN™); alkyl sulfonates, such as busulfan, improsulfan and piposulfan; aziridines, such as benzodopa, carboquone, meturedopa, and uredopa; ethylenimines and methyl triazenes, including altretamine, triethylenemelamine, trietylenephosphoramide, triethylenethiophosphoramide and triethylenethiourea; nitrogen mustards, such as chlorambucil, chlornaphazine, cholophosphamide, estramustine, ifosfamide, mechlorethamine, mechlorethamine oxide hydrochloride, melphalan, novembichin, phenesterine, prednimustine, trofosfamide, uracil mustard; nitrosureas, such as carmustine, chlorozotocin, fotemustine, lomustine, nimustine, ranimustine; antibiotics, such as aclacinomycin, actinomycin, erythromycin, puromycin, bleomycins, dactinomycin, calicheamicin, carabicin, carminomycin, carzinophilin, chromomycin, daunorubicin, detorubicin, 6-diazo-5-oxo-L-norleucine, doxorubicin, epirubicin, esorubicin, idarubicin, marcellomycin, mitomycin, mycophenolic acid, nogalamycin, olivomycins,Gallium nitrate; Hydroxyurea; Lentinan; Lonidamide; Mitoguazone; Mitoxantrone; Mopidamol; Nitrosurea; Pentostatin; Phenamet; Pirarubicin; Podophyllinic acid; 2-Ethylhydrazide; Procarbazine; PSK7; Razoxane; Sizofiran; Spirogermanium; Streptonigrin; Triaziquone; 2',2',2'- Trichlorotriethylamine; Polyamino acids; Vinblastine; Dacarbazine; Mannomustine; Mitobronitol; Mitolactol; Pipobroman; Cytosine arabinoside ("Ara-C"); Cyclophosphamide; Taxanes, e.g. paclitaxel (TAXOL®, Bristol-Myers Squibb Oncology, Princeton, New Jersey) and docetaxel (TAXOTERE®, Rhone-Poulenc Rorer, Antony, France); Chlorambucil; Gemcitabine; 6-Thioguanine; Platinum analogs, e.g. cisplatin and carboplatin; Vinblastine; Platinum; Etoposide (VP- 16); Ifosfamide; Mitomycin C; Mitoxantrone; Vincristine; Vinorelbine; Vinca alkaloids; Novantrone; Teniposide; Daunorubicin; Aminopterin; Xeloda; Ibandronate; CPT-11; Topoisomerase inhibitor RFS 2000; Difluoromethylornithine (DMFO); Retinoic acid; Espamycin; Capecitabine; and pharmaceutically acceptable salts, acids or derivatives of any of the above. The definition also includes anti-hormonal agents that act to regulate or inhibit hormone action on tumors such as anti-estrogens (including for example tamoxifen, raloxifene, aromatase inhibiting 4(5)- imidazoles, 4-hydroxytamoxifen, trioxifene, keoxifene, LY117018, onapristone, and toremifene (Fareston)); and anti-androgens such as flutamide, nilutamide, bicalutamide, leuprolide, and goserelin; and pharmaceutically acceptable salts, acids or derivatives of any of the above. A detailed description of chemotherapeutic agents can be found in, for example, US20180193477A1, which is incorporated by reference herein in its entirety.

[0265] In some embodiments, the antigen binding construct is conjugated to a drug through a cleavable linker, e.g., a linker. A SPBD linker or a maleimidocaproyl-valine-citrulline-para-aminobenzyloxycarbonyl (VC) linker. In some embodiments, the antigen binding construct is conjugated to a drug through a non-cleavable linker, e.g., a linker. A MCC linker formed using SMCC or sulfo-SMCC. One of skill in the art, with knowledge of the art and consideration of relevant factors (e.g., the attachment site on the antigen binding construct, any structural constraints and hydrophobicity of the drug) can readily select an appropriate linker for a given ADC (see, e.g., Nolting, Chapter 5, Antibody-Drug Conjugates: Methods in Molecular Biology, 2013, Ducry (Ed.), Springer). In certain embodiments, a number of specific linker-toxin combinations have been described and can be used with the antigen binding constructs described herein to prepare ADCs. Examples include, but are not limited to, cleavable peptidyl linkers with auristatins, e.g., MMAE and MMAF, camptothecins, e.g., SN-38, duocarmycins, and PBD dimers; non-cleavable MC-based linkers with auristatins MMAF and MMAE; acid-labile hydrazone-based linkers with calicheamicin and doxorubicin; disulfide-based maytansinoid linkers, e.g., DM1 and DM4, and bis-maleimide trioxaethylene glycol (BMPEO)-based maytansinoid DM1 linkers. Some therapeutic agents and linkers are described in Peters & Brown, (2015) Biosci. Rep. e00225; Dosio et al., (2014) Recent Patents on Anti-Cancer Drug Discovery 9:35-65; U.S. Patent Publication Nos. US2015 / 0374847 and US20180193477A1; the entire contents of which are incorporated herein by reference in their entireties.

[0266] Depending on the drug desired and the linker selected, one of skill in the art can select an appropriate method to conjugate them together. For example, some conventional conjugation methods, such as amine conjugation methods, can be used to form the desired drug-linker complex, which still contains a reactive group for conjugation to the antibody through a covalent linkage. In some embodiments, drug-maleimide complexes (i.e., maleimide-linked drugs) can be used in the payload bearing reactive groups in the present context. The most common reactive group that is able to bind to thiol groups in ADC preparation is maleimide. In addition, organic bromides, iodides are also frequently used.

[0267] ADCs can be prepared by one of several routes known in the art using organic chemistry reactions, conditions, and reagents known to those skilled in the art, as described in Bioconjugate Techniques (GT Hermanson, 2013, Academic Press). For example, conjugation can be achieved by: (1) reacting a nucleophilic or electrophilic group of an antibody with a divalent linker reagent to form an antibody-linker intermediate Ab-L via a covalent bond, which is then conjugated to an activated drug moiety D; or (2) reacting a nucleophilic or electrophilic group of a drug moiety with a linker reagent to form a drug-linker intermediate DL via a covalent bond, which is then conjugated to a nucleophilic or electrophilic group of an antibody. Conjugation methods (1) and (2) can be used with a variety of antibodies, drug moieties, and linkers to prepare the ADCs described herein. Various prepared linkers, linker components, and toxins are commercially available or can be prepared using standard synthetic organic chemistry techniques. These methods are described in March's Advanced Organic Chemistry (Smith & March, 2006, Sixth Ed., Wiley); Toki et al., (2002) J. Org. Chem. 67:1866-1872; Frisch et al., (1997) Bioconj. Chem. 7:180-186; Bioconjugate Techniques (GT Hermanson, 2013, Academic Press); US20210379193A1 and US20180193477A1, the entire contents of which are incorporated herein by reference. In addition, many preformed drug linkers suitable for reaction with the selected antigen-binding construct are also commercially available, for example, linker toxins comprising DM1, DM4, MMAE, MMAF or Duocarmycin SA are available from Creative BioLabs (Shirley, NY).

[0268] Several specific embodiments of ADC preparation methods are known in the art and described in U.S. Patent No. 4,070,007. U.S. Patent No. 8,624,003 (one-pot), U.S. Patent No. 8,163,888 (one-step), and U.S. Patent No. 8,163,888 (one-step), U.S. Patent No. 5,208,020 (two-step), and US20180193477A1, the entire contents of which are incorporated herein by reference in their entirety. Other methods are known in the art and include Antibody-drug conjugates: Methods in Molecular Biology, 2013, Ducry (Ed.), Springer.

[0269] Drug loading is represented by the number of drug moieties per antibody in an ADC molecule. For some antibody-drug conjugates, drug loading can be limited by the number of attachment sites on the antibody. For example, when the linker is a cysteine thiol, according to certain exemplary embodiments described herein, the drug loading can range from 0 to 8 drug moieties per antibody. In certain embodiments, higher drug loading, e.g., p > 5, can result in aggregation, insolubility, toxicity, or loss of cell permeability of certain antibody-drug conjugates. In certain embodiments, the average drug loading of an antibody-drug conjugate ranges from 1 to about 8; from about 2 to about 6; or from about 3 to about 5. In fact, it has been shown that for certain antibody-drug conjugates, the optimal ratio of drug moieties per antibody is about 4. In some embodiments, the drug to antibody ratio (DAR) is about or at least 1, 2, 3, 4, 5, 6, 7, or 8. In some embodiments, the average DAR in a composition is from about 1 to about 2, from about 2 to about 3, from about 3 to about 4, from about 3 to about 5, from about 4 to about 5, from about 5 to about 6, from about 6 to about 7, or from about 7 to about 8.

[0270] Antibody and ADC properties

[0271] An antibody or antigen-binding fragment thereof according to described herein, or an ADC derived therefrom, can be an agonist or an antagonist. In some embodiments, by binding to CD79b, the antibody can inhibit CD79b-mediated BCR signaling.

[0272] In some embodiments, the antibody (or antigen-binding fragment thereof) or ADC derived therefrom specifically binds CD79b (e.g., human CD79b, monkey CD79b (e.g., rhesus, cynomolgus), dog CD79b, mouse CD79b) with an off rate. The off rate (koff) is less than 0.1 s-1, less than 0.01 s-1, less than 0.001 s-1, less than 0.0001 s-1, less than 0.00001 s-1, less than 0.000001 s-1, or less than 0.0000001 s-1. In some embodiments, the off rate (koff) is greater than 0.01 s-1, greater than 0.001 s-1, greater than 0.0001 s-1, greater than 0.00001 s-1, greater than 0.000001 s-1, greater than 0.0000001 s-1, or greater than 0.00000001 s-1.

[0273] In some embodiments, the on rate (kon) is greater than 1 x 102 / Ms, greater than 1 x 103 / Ms, greater than 1 x 104 / Ms, greater than 1 x 105 / Ms, or greater than 1 x 106 / Ms. In some embodiments, the on rate (kon) is less than 1 x 105 / Ms, less than 1 x 106 / Ms, or less than 1 x 107 / Ms. In some embodiments, the KD is less than 50 nM, 30 nM, 20 nM, 15 nM, 10 nM, 9 nM, 8 nM, 7 nM, 6 nM, 5 nM, 4 nM, 3 nM, 2 nM, or 1 nM. In some embodiments, the KD is greater than 1 x 10-7M, greater than 1 x 10-8M, greater than 1 x 10-9M, greater than 1 x 10-10M, greater than 1 x 10-11M, greater than 1 x 10-12M, greater than 1 x 10-13M, greater than 1 x 10-14M.

[0274] General techniques for measuring the affinity of an antibody for an antigen include, for example, BLI, ELISA, RIA, flow cytometry, and surface plasmon resonance (SPR). In some embodiments, the antibodies described herein, or antigen-binding fragments thereof, or ADCs derived therefrom, bind human CD79b, monkey CD79b, dog CD79b, and / or mouse CD79b. In some embodiments, the antibodies do not bind human CD79b, monkey CD79b, dog CD79b, and / or mouse CD79b.

[0275] Additionally, alternatively spliced ​​isoforms of CD79b have been described in chronic lymphocytic leukemia. This isoform (also referred to as the "short isoform") encodes 125 amino acids (SEQ ID NO: 67) and differs from the wild-type 229 amino acids (also referred to as the "long isoform") (SEQ ID NO: 68) by the deletion of exon 3, which essentially encodes the majority of the extracellular domain. In some embodiments, the anti-CD79b antibodies described herein can bind to both isoforms of CD79b. In some embodiments, the anti-CD79b antibodies bind to the CD79b isoform (e.g., SEQ ID NO: 67). In some embodiments, the anti-CD79b antibodies do not bind to the CD79b isoform (e.g., SEQ ID NO: 67). In some embodiments, the anti-CD79b antibodies bind to wild-type CD79b (e.g., SEQ ID NO: 68). In some embodiments, the antibodies described herein bind to the extracellular domain of CD79b.

[0276] In some embodiments, the anti-CD79b antibody binds to a CD79b variant (e.g., SEQ ID NO: 2). In some embodiments, the anti-CD79b antibody does not bind to a CD79b variant (e.g., SEQ ID NO: 2). In some embodiments, the anti-CD79b antibody binds to an epitope located within amino acids 1-13 of the ECD of CD79b (e.g., SEQ ID NO: 1).

[0277] In some embodiments, the antibodies or antigen-binding fragments thereof described herein or ADCs derived therefrom are added to Ramos cells to detect internalization rates. In some embodiments, at different time points (e.g., 1 hour, 3 hours, or 6 hours), the antibodies or antigen-binding fragments thereof described herein or ADCs derived therefrom have an internalization rate of 5% or more, 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, or 98% or more. In some embodiments, the antibodies or antigen-binding fragments thereof described herein or ADCs derived therefrom have a slower internalization rate than polatuzumab.

[0278] In some embodiments, thermal stability is determined. The antibodies or antigen-binding fragments thereof described herein, or ADCs derived therefrom, may have a Tm greater than 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, or 95°C. In some embodiments, the Tm is less than 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, or 95°C.

[0279] Since IgG can be described as a multi-domain protein, the melting curve sometimes shows two transitions, namely a first denaturation temperature, Tm1, and a second denaturation temperature, Tm2. The presence of these two peaks generally indicates denaturation of the Fc domain (Tm1) and the Fab domain (Tm2), respectively. Thus, in some embodiments, the antibodies or antigen-binding fragments described herein have a Tm1 greater than 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, or 95°C. In some embodiments, the antibodies or antigen-binding fragments described herein have a Tm2 greater than 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, or 95°C.

[0280] In some embodiments, Tm, Tm1, Tm2 is less than 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, or 95°C.

[0281] In some embodiments, an antibody or antigen-binding fragment thereof described herein, or an ADC derived therefrom, can bind human or monkey CD79b as detected by ELISA. In some embodiments, an antibody or antigen-binding fragment described herein, or an ADC derived therefrom, can bind human or monkey CD79b with an IC50 of less than 200 nM, less than 100 nM, less than 50 nM, less than 10 nM, less than 5 nM, less than 1 nM, less than 0.75 nM, less than 0.5 nM, or less than 0.25 nM.

[0282] In some embodiments, an antibody or antigen-binding fragment thereof described herein, or an ADC derived therefrom, can bind the same epitope of CD79b. In some embodiments, an antibody or antigen-binding fragment thereof described herein, or an ADC derived therefrom, can bind a different epitope of CD79b.

[0283] In some embodiments, an antibody or antigen-binding fragment thereof described herein, or an ADC derived therefrom, can bind malignant B cell lines with high and low CD79b antigen density (e.g., BJAB, Ramos, Daudi, SU-DHL-4, and Nalm-6) as determined by flow cytometry. In some embodiments, the EC50 is less than 200 nM, less than 100 nM, less than 50 nM, less than 10 nM, less than 5 nM, less than 1 nM, less than 0.75 nM, less than 0.5 nM, or less than 0.25 nM.

[0284] In some embodiments, an antibody or antigen-binding fragment thereof described herein, or an ADC derived therefrom, can bind human B cells with a higher cell surface binding affinity than polatuzumab. In some embodiments, the EC50 is less than 200 nM, less than 100 nM, less than 50 nM, less than 10 nM, less than 5 nM, less than 1 nM, less than 0.75 nM, less than 0.5 nM, or less than 0.25 nM.

[0285] In some embodiments, an antibody or antigen-binding fragment thereof described herein, or an ADC derived therefrom, can bind cell surface CD79b on B lymphocytes of chronic lymphocytic leukemia (CLL) patients. In some embodiments, the binding is more effective than polatuzumab.

[0286] In some embodiments, the ADC described herein has an average drug to antibody ratio (DAR) of higher than 3, higher than 3.2, higher than 3.4, higher than 3.6, higher than 3.8, higher than 4, higher than 4.2, higher than 4.4, or higher than 4.6 as determined by HPLC. In some embodiments, the ADC described herein has an average DAR of lower than 3, lower than 3.2, lower than 3.4, lower than 3.6, lower than 3.8, lower than 4, lower than 4.2, lower than 4.4, or lower than 4.6 as determined by HPLC. In some embodiments, the DAR is about 4.

[0287] In some embodiments, the antibody or antigen-binding fragment thereof described herein or ADC derived therefrom has a tumor growth inhibition percentage (TGI%) of greater than 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 110%, 120%, 130%, 140%, 150%, 160%, 170%, 180%, 190%, or 200%. In some embodiments, the antibody or antigen-binding fragment thereof described herein or ADC derived therefrom has a tumor growth inhibition percentage of less than 60%, 70%, 80%, 90%, 100%, 110%, 120%, 130%, 140%, 150%, 160%, 170%, 180%, 190%, or 200%. The TGI% can be determined 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 days after the start of treatment, or 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 months after the start of treatment. According to use herein, the tumor growth inhibition percentage (TGI%) is calculated using the following formula:

[0288] TGI (%) = [1-(Ti-T0) / (Vi-V0)]x100

[0289] Ti is the average tumor volume of the treatment group on day i. T0 is the average tumor volume of the treatment group on day 0. Vi is the average tumor volume of the control group on day i. V0 is the average tumor volume of the control group on day 0.

[0290] In some embodiments, the antibody or antigen-binding fragment thereof described herein or ADC derived therefrom can bind to tumor cells expressing CD79b. In some embodiments, the antibody or antigen-binding fragment described herein or ADC derived therefrom can induce complement-dependent cytotoxicity (CDC) and / or antibody-dependent cellular cytotoxicity (ADCC) and kill tumor cells.

[0291] In some embodiments, the antibodies or antigen-binding fragments thereof described herein, or ADCs derived therefrom, have a functional Fc region. In some embodiments, the effector function of the functional Fc region is antibody-dependent cell-mediated cytotoxicity (ADCC). In some embodiments, the effector function of the functional Fc region is phagocytosis. In some embodiments, the effector function of the functional Fc region is ADCC and phagocytosis.

[0292] In some embodiments, the Fc region is human IgG1, human IgG2, human IgG3, or human IgG4. In some embodiments, the antibody is a humanized IgG1 antibody, optionally with an S1 mutation, a LALA mutation, an N297A mutation, a YTE mutation, and / or a FLAA mutation. In some embodiments, the antibody is a humanized IgG4 antibody, optionally with an S1 mutation, a LALA mutation, an N297A mutation, a YTE mutation, and / or a FLAA mutation.

[0293] In some embodiments, the antibodies or antigen-binding fragments described herein, or ADCs derived therefrom, do not have a functional Fc region. For example, the antibodies or antigen-binding fragments are Fab, Fab', F(ab')2, and Fv fragments. In some embodiments, the Fc region has a LALA mutation (L234A and L235A mutations according to EU numbering) or a LALA-PG mutation (L234A, L235A, P329G mutations according to EU numbering). In some embodiments, the Fc region has a FLAA mutation (F234A and L235A according to EU numbering). In some embodiments, the Fc region has an S1 mutation (S239D and I332E mutations according to EU numbering). In some embodiments, the Fc region has an N297A mutation according to EU numbering. In some embodiments, the Fc region has a YTE mutation (M252Y, S254T, and T256E according to EU numbering).

[0294] Method for preparing anti-CD79b antibodies

[0295] Isolated fragments of human CD79b can be used as immunogens to generate antibodies using standard techniques for polyclonal and monoclonal antibody production. Polyclonal antibodies can be generated in animals by multiple injections (e.g., subcutaneous or intraperitoneal) of the antigenic peptide or protein. In some embodiments, the antigenic peptide or protein is injected with at least one adjuvant. In some embodiments, the antigenic peptide or protein can be conjugated to an agent that is immunogenic in the species to be immunized. Animals can be injected with the antigenic peptide or protein more than once (e.g., two, three, or four times).

[0296] A full-length polypeptide or protein (or an extracellular region thereof) can be used, or an antigenic peptide fragment thereof can be used as an immunogen. An antigenic peptide of a protein comprises at least 8 (e.g., at least 10, 15, 20, or 30) amino acid residues of the amino acid sequence of CD79b and comprises an epitope of the protein such that an antibody formed against the peptide forms a specific immune complex with the protein. As noted above, the full-length sequence of human CD79b is known in the art. In some embodiments, a human CD79b protein with an Fc tag or a His tag is used as an immunogen. In some embodiments, the extracellular domain (ECD) of human CD79b is used as an immunogen.

[0297] Immunogens are typically used to prepare antibodies by immunizing a suitable subject (e.g., a human or transgenic animal expressing at least one human immunoglobulin locus). Suitable immunogenic preparations can include, for example, recombinantly expressed or chemically synthesized polypeptides (e.g., fragments of human CD79b). The preparations can also include an adjuvant, such as Freund's complete or incomplete adjuvant, or similar immunostimulatory agents.

[0298] Polyclonal antibodies can be prepared according to the above by immunizing a suitable subject with a CD79b polypeptide or an antigenic peptide thereof, such as a portion of CD79b. The antibody titer of the immunized subject can be monitored over time by standard techniques, such as enzyme-linked immunoabsorbent assay (ELISA) using immobilized CD79b polypeptide or peptide. If desired, the antibody molecules can be isolated from the mammal (such as from the blood) and further purified by well-known techniques, such as protein G chromatography on protein A, to obtain the IgG fraction. At an appropriate time after immunization, for example, when the specific antibody titer is the highest, the antibody-producing cells can be obtained from the subject and used to prepare monoclonal antibodies by standard techniques, such as the hybridoma technique originally described by Kohler et al. (Nature 256:495-497, 1975), the human B cell hybridoma technique (Kozbor et al., Immunol. Today 4:72, 1983), the EBV hybridoma technique (Cole et al., Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, Inc., pp. 77-96, 1985), or trioma techniques. Techniques for producing hybridomas are well known (see generally Current Protocols in Immunology, 1994, Coligan et al. (Eds.), John Wiley & Sons, Inc., New York, NY). Hybridoma cells that produce the monoclonal antibodies are detected by screening the hybridoma culture supernatants for antibodies that bind the polypeptide or epitope of interest, for example, using standard ELISA assay methods.

[0299] Variants of the antibodies or antigen-binding fragments described herein can be prepared by introducing appropriate nucleotide changes into the DNA encoding a human, humanized, or chimeric antibody or antigen-binding fragment thereof described herein, or by peptide synthesis. Such variants include, for example, deletions from, insertions into, or substitutions of residues within the amino acid sequence of an antigen-binding site or antigen-binding domain of an antibody. Within such variant populations, some antibodies or antigen-binding fragments will have increased affinity for the target protein, e.g., CD79b. Any combination of deletion, insertion, and / or substitution can be made to obtain an antibody or antigen-binding fragment thereof having increased binding affinity for the target. Introducing amino acid changes into an antibody or antigen-binding fragment can also alter or introduce new post-translational modifications to the antibody or antigen-binding fragment, such as changing (e.g., increasing or decreasing) the number of glycosylation sites, changing the type of glycosylation site (e.g., changing the amino acid sequence so that a different sugar is attached by enzymes present in the cell), or introducing new glycosylation sites.

[0300] The antibodies described herein can be derived from any animal species, including mammals. Non-limiting examples of natural antibodies include those derived from humans, primates (such as monkeys and apes), rabbits, cows, pigs, horses, sheep, camelids (such as camels and llamas), chickens, goats, and rodents (such as rats, mice, hamsters, and rabbits), including transgenic animals that have been genetically engineered to produce human antibodies.

[0301] Human antibodies and humanized antibodies include antibodies having variable and constant regions that are derived from human germline immunoglobulin sequences (or having the same amino acid sequence as that derived from those). Human antibodies may include amino acid residues not encoded by human germline immunoglobulin sequences (such as mutations introduced by random or site-directed mutagenesis in vitro or by somatic mutation in vivo), for example, in the CDRs.

[0302] Humanized antibodies typically have a human framework (FR) grafted with non-human CDRs. Thus, a humanized antibody has one or more amino acid sequences introduced therein from a non-human source. These non-human amino acid residues are typically referred to as "input" residues and are typically taken from the "input" variable domain. Humanization can essentially be performed by, for example, replacing the corresponding sequence of a human antibody with a rodent CDR or CDR sequence. These methods are described in, for example, Jones et al., Nature, 321:522-525 (1986); Riechmann et al., Nature, 332:323-327 (1988); Verhoeyen et al., Science, 239:1534-1536 (1988); each of which is incorporated herein by reference in its entirety. Therefore, a "humanized" antibody is a chimeric antibody in which substantially less than a complete human V domain has been replaced by a corresponding sequence from a non-human species. In fact, a humanized antibody is typically a non-human antibody in which some CDR residues and some FR residues are replaced by residues from similar sites in a human antibody.

[0303] The selection of human VH and VL domains for preparing humanized antibodies is very important for reducing immunogenicity. According to the so-called "best match" method, the V domain sequence of a non-human antibody is screened against the entire library of known human domain sequences. Then, the human sequence that is closest to the non-human animal sequence is accepted as the human FR of the humanized antibody (Sims et al., J. Immunol., 151:2296 (1993); Chothia et al., J. Mol. Biol., 196:901 (1987)).

[0304] More importantly, the antibody is humanized with retention of high specificity and affinity for the antigen and other favorable biological properties. To achieve this goal, humanized antibodies can be prepared by a process of analysis of the parental sequences and various conceptual humanized products using three-dimensional models of the parental and humanized sequences. Three-dimensional immunoglobulin models are commonly available and are familiar to those skilled in the art. Computer programs are available which illustrate and display probable three-dimensional conformational structures of selected candidate immunoglobulin sequences. Inspection of these displays can enable analysis of the likely role of the residues in the functioning of the candidate immunoglobulin sequence, i.e., the analysis of residues that influence the ability of the candidate immunoglobulin to bind its antigen. In this way, FR residues can be selected and combined from the recipient and import sequences so that the desired antibody characteristic, such as increased affinity for the target antigen, is achieved. In certain embodiments, the humanized antibody will comprise the VH and VL domains in the same order and with the same linkage as those found in the parent antibody.

[0305] Generally, the amino acid sequence variants of the human, humanized or chimeric anti-CD79b antibodies will comprise an amino acid sequence that is at least 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to a sequence found in the light or heavy chain of the original antibody.

[0306] Identity or homology to the original sequence is typically the percentage of amino acid residues in the candidate sequence that are identical with the sequence, which is present in the human, humanized or chimeric anti-CD79b antibody or fragment, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity, and not considering any conservative substitutions as part of the sequence identity.

[0307] Other modifications can be made to the anti-CD79b antibody or antigen-binding fragment. For example, cysteine residues can be introduced into the Fc region to allow interchain disulfide bond formation in this region. The resulting homodimeric antibodies can have increased in vitro and / or in vivo half-lives. Homodimeric antibodies with extended half-lives in vivo can also be prepared using heterobifunctional cross-linkers. See, e.g., Wolff et al. (Cancer Res. 53:2560-2565, 1993). Alternatively, antibodies with dual Fc regions can be designed (see, e.g., Stevenson et al., Anti-Cancer Drug Design 3:219-230, 1989).

[0308] In some embodiments, the anti-CD79b antibody or antigen-binding fragment thereof can be covalently modified. These covalent modifications can be made either by chemical or enzymatic synthesis, or by enzymatic or chemical cleavage. Other types of covalent modifications of the antibody or antibody fragment are introduced into the molecule by reacting target amino acid residues of the antibody or fragment with an organic derivatizing agent that is capable of reacting with selected side chains or N- or C-terminal residues.

[0309] In some embodiments, provided antibody variants have carbohydrate structures lacking fucose attached (directly or indirectly) to the Fc region. For example, the amount of fucose in such antibodies can range from 1% to 80%, 1% to 65%, 5% to 65%, or 20% to 40%. The amount of fucose is determined by calculating the average amount of fucose within the Asn297 carbohydrate chain relative to the sum of all carbohydrate structures (e.g., complex, hybrid, and high-mannose structures) attached to Asn297 as measured by MALDI-TOF mass spectrometry, as described in WO 2008 / 077546. Asn297 refers to the asparagine residue located at approximately position 297 in the Fc region (Eu numbering of Fc region residues; or position 314 in Kabat numbering); however, due to minor sequence variation within antibodies, Asn297 may also be located approximately ±3 amino acids upstream or downstream of position 297, i.e., between positions 294 and 300. Such fucosylated variants may have improved ADCC function. In some embodiments, to reduce glycan heterogeneity, the Fc region of the antibody can be further engineered to replace the asparagine at position 297 with alanine (N297A).

[0310] In some embodiments, in order to avoid Fab arm exchange to improve production efficiency, the Fc region of the antibody is further modified to replace the serine at position 228 (EU numbering) of IgG4 with proline (S228P). A detailed description of the S228 mutation is provided, for example, in Silva et al. "The S228P mutation prevents in vivo and in vitro IgG4 Fab-arm exchange as demonstrated using a combination of novel quantitative immunoassays and physiological matrix preparation." Journal of Biological Chemistry 290.9 (2015): 5462-5469, which is incorporated herein by reference in its entirety.

[0311] recombinant vector

[0312] The present invention also provides recombinant vectors (e.g., expression vectors) comprising an isolated polynucleotide disclosed herein (e.g., a polynucleotide encoding a polypeptide disclosed herein), a host cell into which the recombinant vector is introduced (i.e., such that the host cell contains the polynucleotide and / or a vector comprising the polynucleotide), and production of the recombinant antibody polypeptide or fragment thereof by recombinant techniques.

[0313] As used herein, a "vector" is any construct capable of delivering one or more polynucleotides of interest to a host cell when the vector is introduced into the host cell. An "expression vector" is capable of delivering and expressing one or more polynucleotides of interest as encoded polypeptides in a host cell into which the expression vector has been introduced. Thus, in an expression vector, the polynucleotide of interest is positioned for expression in the vector by being operably linked to regulatory elements (e.g., promoters, enhancers, and / or polyadenylation tails) within the vector or in the genome. The polynucleotide of interest is positioned at, near, or flanking the host cell at the integration site of the polynucleotide of interest so that the polynucleotide of interest will be translated in the host cell into which the expression vector has been introduced.

[0314] As used herein, a "vector" is any construct capable of delivering one or more polynucleotides of interest to a host cell when the vector is introduced into the host cell. An "expression vector" is capable of delivering and expressing one or more polynucleotides of interest as encoded polypeptides in a host cell into which the expression vector has been introduced. Thus, in an expression vector, the polynucleotide of interest is positioned for expression in the vector by being operably linked to regulatory elements (e.g., promoters, enhancers, and / or polyadenylation tails) within the vector or in the genome. The polynucleotide of interest is positioned at, near, or flanking the integration site of the polynucleotide of interest so that the polynucleotide of interest will be translated in the host cell into which the expression vector has been introduced.

[0315] Vectors can be introduced into host cells by methods known in the art, such as electroporation, chemical transfection (e.g., DEAE-dextran), transformation, transfection and infection, and / or transduction (e.g., with recombinant viruses). Thus, non-limiting examples of vectors include viral vectors (which can be used to generate recombinant viruses), naked DNA or RNA, plasmids, cosmids, phage vectors, and DNA or RNA expression vectors conjugated to cationic condensing agents.

[0316] In some embodiments, the polynucleotides described herein (e.g., polynucleotides encoding the polypeptides described herein) are introduced using a viral expression system (e.g., vaccinia or other poxvirus, retrovirus, or adenovirus), which can involve the use of a non-pathogenic (defective), replication-competent virus, or can involve the use of a replication-defective virus. In the latter case, viral propagation generally occurs only in complementing viral packaging cells. Suitable systems are described in Fisher-Hoch et al., 1989, Proc. Natl. Acad. Sci. USA 86:317-321; Flexner et al., 1989, Ann. N.Y. Acad Sci. 569:86-103; Flexner et al., 1990, Vaccine, 8:17-21; U.S. Pat. Nos. 4,603,112, 4,769,330, and 5,017,487; WO 89 / 01973; U.S. Pat. No. 4,777,127; GB 2,200,651; EP 0,345,242; WO 91 / 02805; Berkner-Biotechniques, 6:616-627, 1988; Rosenfeld et al., 1991, Science, 252:431-434; Kolls et al., 1994, Proc. Natl. Acad. Sci. USA, 91:215-219; Kass-Eisler et al., 1993, Proc. Natl. Acad. Sci. USA, 90:11498-11502; Guzman et al., 1993, Circulation, 88:2838-2848; and Guzman et al., 1993, Cir. Res., 73:1202-1207. Techniques for incorporating DNA into such expression systems are well known to those of ordinary skill in the art. DNA can also be "naked," as described in Ulmer et al., 1993, Science, 259:1745-1749, and Cohen, 1993, Science, 259:1691-1692. Uptake of naked DNA can be increased by coating the DNA onto biodegradable beads that can be efficiently transported into cells.

[0317] For expression, the DNA insert containing the polynucleotide encoding the antibody or polypeptide described herein can be operatively linked to a suitable promoter (such as a heterologous promoter), e.g., the phage lambda PL promoter, the E. coli lac, trp, and tac promoters, the SV40 early and late promoters, and promoters of retroviral LTRs, among others. Other suitable promoters are known to the skilled artisan. The expression construct can further comprise sites for transcription initiation, termination, and ribosome binding in the region of transcription. The coding portion of the mature transcript expressed by the construct can include a translation initiation codon, ATG, at the availability of the polypeptide to be translated and a translation termination codon, UAA, UGA, or UAG.

[0318] As indicated, the expression vector can include at least one selectable marker. Such markers include dihydrofolate reductase for eukaryotic cell culture, or neomycin resistance for culturing in e. coli and other bacteria. Representative examples of appropriate hosts include, but are not limited to, bacterial cells, such as E. coli, Streptomyces, and Salmonella typhimurium cells; fungal cells, such as yeast cells; Drosophila S2, Spodoptera Sf9 and other insect cells; CHO, COS, Bowes melanoma, HK 293 cells and the like animal cells; and plant cells. Appropriate culture media and conditions for the host cells described herein are known in the art.

[0319] Non-limiting vectors for use in bacteria include pQE70, pQE60, and pQE-9 available from Qiagen; pBS, Phagescript, Bluescript, pNH8A, pNH16a, pNH18A, pNH46A available from Stratagene; and ptrc99a, pKK223-3, pKK233-3, pDR540, pRIT5 available from Pharmacia. Non-limiting eukaryotic vectors include pWLNEO, pSV2CAT, pOG44, pXT1, and pSG available from Stratagene; pSVK3, pBPV, pMSG, and pSVL available from Pharmacia. Other suitable vectors will be readily apparent to the skilled artisan.

[0320] Non-limiting bacterial promoters suitable for use include the E. coli lacI and lacZ promoters, the T3 and T7 promoters, the gpt promoter, the lambda PR and PL promoters, and the trp promoter. Suitable eukaryotic promoters include the CMV immediate early promoter, the HSV thymidine kinase promoter, the early and late SV40 promoters, the promoters of retroviral LTRs, such as the Rous sarcoma virus (RSV) promoter, and the metallothionein promoter, such as the mouse metallothionein-I promoter.

[0321] In S. cerevisiae, a number of vectors can be used, which contain constitutive or inducible promoters, such as the alpha factor, alcohol oxidase, and PGH. Related descriptions are found in Ausubel et al. (1989) Current Protocols in Molecular Biology, John Wiley & Sons, New York, N.Y, and Grant et al., Methods Enzymol., 153: 516-544 (1997).

[0322] Constructs can be introduced into host cells by calcium phosphate transfection, DEAE-dextran mediated transfection, cationic lipid mediated transfection, electroporation, transduction, infection, or other methods. Such methods are described in many standard laboratory manuals, such as Davis et al., Basic Methods In Molecular Biology (1986), which is incorporated by reference in its entirety.

[0323] Transcription of DNA encoding antibodies of the present teachings by higher eukaryotes can be increased by inserting an enhancer sequence into the vector. Enhancers are cis-acting elements of DNA, usually about 10 to 300 bp in length, that act to increase the transcriptional activity of a promoter in a given host cell type. Examples of enhancers include the SV40 enhancer, which is located 100 to 270 base pairs upstream from the replication origin of SV40, the cytomegalovirus early-cycle promoter enhancer, the mulvirus enhancer, and the adenovirus enhancer.

[0324] To secrete translated proteins into the endoplasmic reticulum lumen, periplasmic space, or extracellular environment, appropriate secretion signals can be incorporated into the expressed polypeptides. The signals can be endogenous to the polypeptides or they can be heterologous signals.

[0325] Polypeptides, such as antibodies, can be expressed in modified form, such as a fusion protein (e.g., a GST-fusion protein) or with a histidine tag, and can include not only a secretion signal, but also additional heterologous functional regions. For example, an additional region of amino acids, particularly charged amino acids, can be added to the N-terminus of the polypeptide to improve stability and persistence in the host cell during purification procedures or during subsequent handling and storage. In addition, a peptide moiety can be added to the polypeptide to facilitate purification. These regions can be removed prior to final preparation of the polypeptide. The addition of peptide moieties to polypeptides to cause secretion or excretion, improve stability, and facilitate purification, among other things, are techniques familiar and routine in the art.

[0326] Therapeutic methods

[0327] The antibodies or antigen-binding fragments thereof of the present disclosure can be used for various therapeutic purposes.

[0328] In one aspect, the present disclosure features methods of treating cancer in a subject, methods of reducing the rate at which tumor volume increases over time in a subject, methods of reducing the risk of developing metastasis, or methods of reducing metastasis. In some embodiments, the treatment can stop, slow, delay, or inhibit the progression of the cancer. In some embodiments, the treatment can result in a reduction in the number, severity, and / or duration of one or more symptoms of the cancer in the subject.

[0329] In one aspect, the present disclosure features methods comprising administering to a subject in need thereof (e.g., a subject having or identified or diagnosed with cancer), such as breast cancer (e.g., triple negative breast cancer), carcinoid, cervical cancer, endometrial cancer, glioma, head and neck cancer, liver cancer, lung cancer, small cell lung cancer, lymphoma, melanoma, ovarian cancer, pancreatic cancer, prostate cancer, renal cancer, colorectal cancer, gastric cancer, testicular cancer, thyroid cancer, bladder cancer, urethral cancer, or a hematological malignancy, a therapeutically effective amount of an antibody or antigen-binding fragment thereof disclosed herein. In some embodiments, the cancer is unresectable melanoma or metastatic melanoma, non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC), bladder cancer, or metastatic hormone-refractory prostate cancer. In some embodiments, the cancer is NSCLC, ovarian cancer, melanoma, colorectal cancer, breast cancer, a hematological malignancy, head and neck cancer, gastrointestinal cancer, bladder cancer, or bone cancer. In some embodiments, the subject has Hodgkin's lymphoma. In some embodiments, the subject has triple negative breast cancer (TNBC), gastric cancer, urothelial cancer, Merkel cell carcinoma, or head and neck cancer. In some embodiments, the cancer is melanoma, pancreatic cancer, mesothelioma, a hematological malignancy, in particular non-Hodgkin's lymphoma, lymphoma, chronic lymphocytic leukemia, or an advanced solid tumor. In some embodiments, the cancer is lymphoma, breast cancer, gastric cancer, pancreatic cancer, prostate cancer, cervical cancer, endometrial cancer, ovarian cancer, or urothelial cancer.

[0330] In some embodiments, the compositions and methods described herein can be used to treat a patient at risk for cancer. Patients having cancer can be identified using various methods known in the art.

[0331] In one aspect, the present disclosure provides methods for treating, preventing, or reducing the risk of developing a condition associated with an abnormal or unwanted immune response, such as an autoimmune condition. These autoimmune diseases include, but are not limited to, alopecia areata, lupus, ankylosing spondylitis, Meniere's disease, antiphospholipid syndrome, mixed connective tissue disease, autoimmune Addison's disease, multiple sclerosis, autoimmune hemolytic anemia, myasthenia gravis, autoimmune hepatitis, pemphigus vulgaris, Behcet's disease, pernicious anemia, bullous pemphigoid, polyarticular arthritis nodosa, cardiomyopathy, polychondritis, oral celiac disease, polyglandular syndrome, chronic fatigue syndrome (CFIDS), polymyalgia rheumatica, chronic inflammatory demyelinating polyneuropathy, polymyositis and dermatomyositis, chronic inflammatory multiple neuropathy, primary agammaglobulinemia, Churg-Strauss syndrome, primary biliary cirrhosis, cicatricial pemphigoid, psoriasis, CREST syndrome, Raynaud phenomenon, cold agglutinin disease, Reiter's syndrome, Crohn's disease, rheumatic fever, discoid lupus, rheumatoid arthritis, cryoglobulinemia, sarcoidosis, fibromyalgia, scleroderma, Grave's disease, Sjogren's syndrome, Guillain-Barre syndrome, stiff-man syndrome, Hashimoto's thyroiditis, Takayasu arteritis, idiopathic pulmonary fibrosis, temporal arteritis / giant cell arteritis, idiopathic thrombocytopenic purpura (ITP), ulcerative colitis, IgA nephropathy, uveitis, diabetes (e.g., Type I), vasculitis, lichen planus, and vitiligo. Anti-CD79b antibodies or antigen-binding fragments thereof can also be administered to a subject to treat, prevent, or reduce the risk of developing a condition associated with an abnormal or unwanted immune response associated with a cell, tissue, or organ transplant, such as a kidney transplant, liver and heart transplant, e.g., graft versus host disease (GVHD), or to prevent allograft rejection. In some embodiments, the subject has a skin disease, a liver disease (e.g., cirrhosis), hidradenitis suppurativa, experimental autoimmune encephalomyelitis. In some embodiments, the subject has a kidney disease, lupus, Sjogren's syndrome, ulcerative colitis, psoriasis, hidradenitis suppurativa, immune thrombocytopenia (ITP), or other inflammatory arthritis. In some embodiments, the subject has multiple sclerosis or myasthenia gravis. In some embodiments, the subject has Crohn's disease, ulcerative colitis, or type 1 diabetes. In some embodiments, the subject has an autoimmune thyroid disease, Grave's disease, multiple sclerosis, psoriasis, inflammatory bowel disease (e.g., Crohn's disease (CD) and ulcerative colitis), rheumatoid arthritis, Sjogren's syndrome, autoimmune nephritis, or systemic lupus erythematosus. In some embodiments, the methods involve administering to the subject an effective amount of a composition comprising an antibody or antigen-binding fragment thereof according to the present disclosure.

[0332] According to the present disclosure, an "effective amount" refers to an amount or dose sufficient to achieve a beneficial or desired result, including halting, slowing, delaying or inhibiting the progression of a disease, such as an autoimmune disease or cancer. An effective amount will vary depending on, for example, the age and weight of the subject to be administered the antibody, antigen-binding fragment, antibody-encoding polynucleotide, vector comprising a polynucleotide, and / or composition thereof, the severity of the symptoms, and the route of administration, and thus can be determined on an individual basis.

[0333] An effective amount can be administered in one or more administrations. For example, an effective amount of an antibody or antigen-binding fragment is an amount sufficient to improve, halt, stabilize, reverse, inhibit, slow and / or delay the progression of an autoimmune disease or cancer in a patient, or an amount sufficient to improve, halt, stabilize, reverse, slow and / or delay the proliferation of a cell (e.g., a biopsy cell, any of the cancer cells or cell lines described herein (e.g., a cancer cell line)) in vitro. As is understood in the art, the effective amount of an antibody or antigen-binding fragment can vary, depending, inter alia, on the patient's history and other factors, such as the type (and / or dosage) of antibody used.

[0334] The effective amount and schedule for administering the antibodies, polynucleotides encoding antibodies, and / or compositions described herein can be determined empirically, and making such determinations is within the skill in the art. Those of skill in the art will appreciate that the dosage to be administered must be varied depending, for example, on the mammal that will receive the antibodies, polynucleotides encoding antibodies, and / or compositions described herein, the route of administration, the particular type of antibody, antigen-binding fragment, and / or composition described herein, and other drugs being administered to the mammal. Guidance for selecting an appropriate dose for an antibody or antigen-binding fragment can be found in the literature regarding therapeutic uses of antibodies and antigen-binding fragments, e.g., Handbook of Monoclonal Antibodies, Ferrone et al., eds., Noges Publications, Park Ridge, N.J., 1985, ch. 22 and pp. 303-357; Smith et al., Antibodies in Human DiagNOis and Therapy, Haber et al., eds., Raven Press, New York, 1977, pp. 365-389.

[0335] A typical daily dose of an effective amount of an antibody is 0.01 mg / kg to 100 mg / kg. In some embodiments, the dose can be less than 100 mg / kg, 10 mg / kg, 9 mg / kg, 8 mg / kg, 7 mg / kg, 6 mg / kg, 5 mg / kg, 4 mg / kg, 3 mg / kg, 2 mg / kg, 1 mg / kg, 0.5 mg / kg, or 0.1 mg / kg. In some embodiments, the dose can be greater than 10 mg / kg, 9 mg / kg, 8 mg / kg, 7 mg / kg, 6 mg / kg, 5 mg / kg, 4 mg / kg, 3 mg / kg, 2 mg / kg, 1 mg / kg, 0.5 mg / kg, 0.1 mg / kg, 0.05 mg / kg, or 0.01 mg / kg. In some embodiments, the dose is about 10 mg / kg, 9 mg / kg, 8 mg / kg, 7 mg / kg, 6 mg / kg, 5 mg / kg, 4 mg / kg, 3 mg / kg, 2 mg / kg, 1 mg / kg, 0.9 mg / kg, 0.8 mg / kg, 0.7 mg / kg, 0.6 mg / kg, 0.5 mg / kg, 0.4 mg / kg, 0.3 mg / kg, 0.2 mg / kg, or 0.1 mg / kg.

[0336] In any of the methods described herein, the at least one antibody, antigen-binding fragment thereof, or pharmaceutical composition (such as any of the antibodies, antigen-binding fragments, or pharmaceutical compositions described herein) and, optionally, the at least one additional therapeutic agent can be administered to the subject at least once per week (such as once per week, twice per week, three times per week, four times per week, once per day, twice per day, or three times per day). In some embodiments, at least two different antibodies and / or antigen-binding fragments are administered in the same composition (such as a liquid composition). In some embodiments, at least one antibody or antigen-binding fragment and at least one additional therapeutic agent are administered in the same composition (such as a liquid composition). In some embodiments, at least one antibody or antigen-binding fragment and at least one additional therapeutic agent are administered in two different compositions (such as a liquid composition containing at least one antibody or antigen-binding fragment and a solid oral composition containing at least one additional therapeutic agent). In some embodiments, the at least one additional therapeutic agent is administered as a pill, tablet, or capsule. In some embodiments, the at least one additional therapeutic agent is administered in a sustained release oral formulation.

[0337] In some embodiments, one or more additional therapeutic agents described herein can be administered to the subject prior to or after administration of the at least one antibody, antigen-binding antibody fragment, or pharmaceutical composition (e.g., any of the antibodies, antigen-binding antibodies described herein). In some embodiments, the one or more additional therapeutic agents and the at least one antibody, antigen-binding antibody fragment, or pharmaceutical composition (e.g., any of the antibodies, antigen-binding antibody fragments, or pharmaceutical compositions described herein) are administered to the subject such that there is an overlap in the biological activity of the one or more additional therapeutic agents and the at least one antibody or antigen-binding fragment (e.g., any of the antibodies or antigen-binding fragments described herein).

[0338] In some embodiments, the at least one antibody, antigen-binding antibody fragment, or pharmaceutical composition (e.g., any of the antibodies, antigen-binding antibody fragments, or pharmaceutical compositions described herein) can be administered to the subject over an extended period of time, such as over a period of at least 1 week, 2 weeks, 3 weeks, 1 month, 2 months, 3 months, 4 months, 5 months, 6 months, 7 months, 8 months, 9 months, 10 months, 11 months, 12 months, 1 year, 2 years, 3 years, 4 years, or 5 years. A skilled medical professional can use any of the methods described herein to determine the length of the treatment period to diagnose or track the effectiveness of the treatment (e.g., to observe at least one symptom of the cancer). Based on the assessment of the effectiveness of the treatment, a skilled medical professional can also vary (e.g., increase or decrease) the identity and number of antibodies or antigen-binding antibody fragments (and / or one or more additional therapeutic agents) administered to the subject, and can also adjust (e.g., increase or decrease) the dosage or frequency of the at least one antibody or antigen-binding antibody fragment (and / or one or more additional therapeutic agents) administered to the subject (e.g., using any of the methods described herein and known in the art).

[0339] In some embodiments, one or more additional therapeutic agents can be administered to the subject. The additional therapeutic agent can comprise one or more inhibitors selected from the group consisting of a B-Raf inhibitor, an EGFR inhibitor, a MEK inhibitor, an ERK inhibitor, a K-Ras inhibitor, a c-Ras inhibitor, a Met, anaplastic lymphoma kinase (ALK) inhibitor, a phosphatidylinositol 3-kinase (PI3K) inhibitor, an Akt inhibitor, an mTOR inhibitor, a dual PI3K / mTOR inhibitor, a Bruton's tyrosine kinase (BTK) inhibitor, and an inhibitor of isocitrate dehydrogenase 1 (IDH1) and / or isocitrate dehydrogenase 2 (IDH2). In some embodiments, the additional therapeutic agent is an inhibitor of indoleamine 2,3-dioxygenase-1) (IDOl) (e.g., epacadostat).

[0340] In some embodiments, the additional therapeutic agent may comprise one or more inhibitors selected from the group consisting of PD-1 inhibitors, LSD1 inhibitors, MDM2 inhibitors, BCL2 inhibitors, CHK1 inhibitors, agents that activate the Hedgehog signaling pathway, and agents that selectively degrade the estrogen receptor.

[0341] In some embodiments, the additional therapeutic agent may include one or more therapeutic agents selected from the group consisting of trabectedin, nab-paclitaxel, trabentanib, pazopanib, cediranib, palbociclib, everolimus, fluoropyrimidine, IFL, regorafenib, Reolysin, Alimta, Zykadia, Sutent, temsirolimus, axitinib, everolimus, sorafenib, Votrient, Pazopanib, IMA-901, AGS-003, cabozantinib, Vinflunine, an Hsp90 inhibitor, Ad-GM-CSF, Temazolomide, IL-2, IFNa, vinblastine, Thalomid, dacarbazine, cyclophosphamide, lenalidomide, azacytidine, lenalidomide, bortezomib, amrubicin, carfilzomib, pralatrexate, and enzastaurin.

[0342] In some embodiments, the additional therapeutic agent may include one or more therapeutic agents selected from the group consisting of an adjuvant, a TLR agonist, tumor necrosis factor (TNF) α, IL-1, HMGB1, an IL-10 antagonist, an IL-4 antagonist, an IL-13 antagonist, an IL-17 antagonist, an HVEM antagonist, an ICOS agonist, a CX3CL1-targeted therapy, a CXCL9-targeted therapy, a CXCL10-targeted therapy, a CCL5-targeted therapy, an LFA-1 agonist, an ICAM1 agonist, and a PD-1 agonist.

[0343] In some embodiments, the subject is administered carboplatin, nab-paclitaxel, paclitaxel, cisplatin, pemetrexed, gemcitabine, FOLFOX, or FOLFIRI.

[0344] In some embodiments, the additional therapeutic agent is an anti-OX40 antibody, an anti-PD-1 antibody, an anti-PD-L2 antibody, an anti-LAG-3 antibody, an anti-TIGIT antibody, an anti-BTLA antibody, an anti-CTLA4 antibody, an anti-ICOS antibody, an anti-CD27 antibody, an anti-4-1BB antibody, an anti-CD40 antibody, an anti-VEGFR2 antibody, an anti-EGFR antibody, an anti-HER2 antibody, a TIM3 antibody, a CD103 antibody, a TGFBR2 antibody, and / or an anti-GITR antibody.

[0345] In one aspect, the present disclosure provides combination therapies. In some embodiments, an anti-CD79b antibody or antigen-binding fragment thereof (such as any of the antibodies described herein) can be administered with an anti-CTLA4 antibody.

[0346] Pharmaceutical compositions and routes of administration

[0347] Also provided herein are pharmaceutical compositions comprising at least one (such as one, two, three, or four) antibody or antigen-binding fragment described herein. Two or more (such as two, three, or four) of any of the antibodies or antigen-binding fragments described herein can be present in the pharmaceutical composition in any combination. The pharmaceutical composition can be formulated in any manner known in the art.

[0348] The pharmaceutical composition is formulated to be compatible with its intended route of administration (such as intravenous, intraarterial, intramuscular, intradermal, subcutaneous, or intraperitoneal). The composition can include sterile diluent (such as sterile water or saline), non-volatile oil, polyethylene glycol, glycerin, propylene glycol, or other synthetic solvents, antibacterial or antifungal agents, for example, benzyl alcohol or methyl parabens, chlorobutanol, phenol, ascorbic acid, thimerosal, and the like, antioxidants, for example, ascorbic acid or sodium bisulfite, chelating agents, for example, ethylenediaminetetraacetic acid, buffers, for example, acetate, citrate, or phosphate, and isotonic agents, for example, sugars (such as glucose), polyalcohols (such as mannitol or sorbitol), or salts (such as sodium chloride) or any combination thereof. Liposomal suspensions can also be used as pharmaceutically acceptable carriers (see, e.g., U.S. Patent No. 4,522,811). The formulation can be prepared and encapsulated in ampoules, syringes, or multiple dose vials. Where required, it can be maintained at the desired temperature (such as in a refrigerated syringe) by the use of, for example, ovophospholipid or surfactants. The absorption of the antibody or antigen-binding fragment thereof can be prolonged and / or enhanced by the inclusion of agents which delay absorption (such as aluminum monostearate and gelatin). Alternatively, controlled release can be achieved by the use of an implant and microencapsulated delivery systems, which can include biodegradable biocompatible polymers (such as ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters, and polylactic acid; Alza Corporation and Nova Pharmaceutical, Inc.).

[0349] Compositions containing one or more of any of the antibodies or antigen-binding fragments described herein can be formulated in dosage unit form (i.e., physically discrete units, each unit containing a predetermined quantity of active compound, to facilitate administration and uniformity of dosage).

[0350] Pharmaceutical compositions for parenteral administration are preferably sterile and substantially isotonic and manufactured in accordance with good manufacturing practice (GMP) conditions. The pharmaceutical composition can be provided in unit dosage form (i.e., the dosage for a single administration). The pharmaceutical composition can be formulated using one or more physiologically acceptable carriers, diluents, excipients or auxiliaries. The formulation depends on the selected route of administration. For injection, the antibody can be formulated in aqueous solutions, preferably in physiologically compatible buffers to reduce discomfort at the site of injection. The solution can contain formulatory agents such as suspending, stabilizing and / or dispersing agents. Alternatively, the antibody can be in lyophilized form for constitution with a suitable carrier, such as sterile pyrogen-free water, before use.

[0351] Toxicity and therapeutic efficacy of the compositions can be determined by standard pharmaceutical procedures in cell cultures or experimental animals (e.g., monkeys). The LD50 (the dose lethal to 50% of the population) and the ED50 (the dose therapeutically effective in 50% of the population) can be determined: the therapeutic index is the ratio LD50: ED50. Formulations that exhibit high therapeutic indices are preferred. When the pharmaceutical agents exhibit adverse side effects, attention should be given to the use of the lowest possible potential harm (i.e., reducing adverse side effects). Toxicity and therapeutic efficacy can be determined by other standard pharmaceutical procedures.

[0352] Data obtained from cell culture assays and animal studies can be used in formulating an appropriate dosage of any given agent for use in a subject (e.g., a human). A therapeutically effective amount of one or more (e.g., one, two, three, or four) antibodies or antigen-binding fragments thereof (e.g., any of the antibodies or antibody fragments described herein) will be an amount that treats a disease in a subject (e.g., kills cancer cells) in a subject (e.g., a human subject identified as having cancer), or a subject identified as being at risk of developing a disease (e.g., a subject who has previously had cancer but is now in remission), reduces the severity, frequency, and / or duration of one or more symptoms of a disease in a subject (e.g., a human). The effectiveness and dosage of any of the antibodies or antigen-binding fragments described herein can be determined by a health care professional or veterinary professional using methods known in the art and by observing one or more symptoms of a disease in a subject (e.g., a human). Certain factors can influence the dosage and timing required to effectively treat a subject (e.g., the severity of the disease or condition, prior treatments, the subject’s general health status and / or age, and the presence of other diseases).

[0353] Exemplary doses include milligram or microgram amounts of any of the antibodies or antigen-binding fragments described herein per kilogram of body weight of the subject (e.g., about 1 pg / kg to about 500 mg / kg; about 100 pg / kg to about 500 mg / kg; about 100 pg / kg to about 50 mg / kg; about 10 pg / kg to about 5 mg / kg; about 10 pg / kg to about 0.5 mg / kg; or about 1 pg / kg to about 50 pg / kg). While these dosages encompass a wide range of amounts, one of ordinary skill in the art will appreciate that the potency of therapeutic agents, including antibodies and antigen-binding fragments thereof, varies widely and that effective amounts can be determined by methods known in the art. Generally, a relatively low dosage is administered first, and the treating health care professional or veterinary professional (in the case of therapeutic applications) or researcher (when still in the development stage) can gradually increase the dosage until an appropriate response is obtained. Also, it is understood that specific dose levels for any particular subject will depend upon a variety of factors, including the activity of the specific compound employed, the age, body weight, general health, sex, and diet of the subject, the time of administration, the route of administration, the rate of excretion, and the half-life of the antibody or antibody fragment in the body.

[0354] The pharmaceutical compositions can be included in a container, pack, or dispenser together with instructions for administration. The present disclosure also provides methods of manufacturing the antibodies or antigen-binding fragments thereof for the various uses described herein.

[0355] Examples

[0356] The present disclosure is further described in the following examples, which do not limit the scope of the disclosure described in the claims.

[0357] Example 1. Generation of anti-CD79b antibodies

[0358] Immunization of rabbits with CD79b antigen

[0359] To generate monoclonal antibodies against human CD79b, two New Zealand white rabbits were immunized with human CD79b ECD antigen (SEQ ID NO: 1, aa. 29-159, with his tag, from AcroBiosystems) using complete Freund’s adjuvant or incomplete Freund’s adjuvant. Serum titers were monitored by ELISA after the second injection.

[0360] Screening of individual B cells for generation of CD79b monoclonal antibodies

[0361] After 3-4 immunizations at 200 pg / rabbit / injection, rabbits with good titers (> 1: 100,000) received a final boost injection and spleens were harvested 7 days after the final injection.

[0362] Isolation of splenocytes from rabbits

[0363] All procedures below (except for centrifugation) were performed in a biological safety cabinet. Rabbit spleens were harvested 7 days after the last boost. Spleen cells were prepared in a sterile cell strainer placed at the bottom of a 100 mm sterile petri dish containing 20 mL of RPMI + 1% penicillin-streptomycin (P / S). Using sterile forceps, the spleen tissue was transferred into the cell strainer. Specifically, while holding the spleen with the forceps, the spleen was cut into small pieces which were then pressed through the mesh of the cell strainer. The tissue pieces were washed with 10 mL of RPMI + 1% P / S. The spleen cells were transferred from the petri dish into a new 50 mL conical tube. RPMI + 1% P / S was added to a final volume of 50 ml. The cells were centrifuged at 400 x g for 5 minutes and the supernatant was aspirated. 13 mL of ACK buffer (Gibco Cat# A1049201) was added to resuspend the cells. The suspended cells were incubated at room temperature for 1 minute. RPMI + 1% P / S was added to reach a final volume of 50 ml. The cells were centrifuged at 400 x g for 5 minutes and the supernatant was aspirated. The cell pellet was resuspended in RPMI + 10% FBS + 1% P / S. The cells were centrifuged at 400 x g for 5 minutes and the supernatant was aspirated. The pellet was resuspended in 15 ml of RPMI + 10% FBS + 1% P / S. The cells were moved into a 50 mL conical tube through a 100 pm cell strainer to remove cell clumps. The spleen cells were then seeded at the desired density (e.g., 4E6 cells / ml) with the appropriate media for sorting. The remaining spleen cells were frozen overnight at -80°C at 6 x 10 7 cells / vial (~1.8ml) in 90% serum + 10% DMSO. The frozen cells were transferred to a liquid nitrogen tank for long-term storage.

[0364] Antigen-specific B cell sorting

[0365] For B cell sorting, B cell media (RPMI-1640, 15% FBS, 1 x HEPES, 1 x 2-ME (2-mercaptoethanol), 1% penicillin / streptomycin) was prepared overnight before sorting. 96-well B cell feeder plates were prepared accordingly the day before sorting. On the day of sorting, suspended and loosely adherent splenocytes were collected by gently pipetting the culture surface of the flasks with a pipette. Cells were then transferred to conical tubes and centrifuged at 400 x g for 3 minutes. Cell pellets were washed twice with fluorescence-activated cell sorting (FACS) buffer (1 x PBS + 0.5% BSA). Biotinylated antigen was added at 5 pg / ml (final concentration). The staining mixture was incubated at room temperature (RT) for 20 minutes. The staining mixture was then centrifuged at 400 x g for 3 minutes and the cells were resuspended in FACS buffer. Cells were transferred to 1.5 ml amber Eppendorf tubes. The staining antibody mixture was then added to the cells. The staining mixture was incubated at 4°C for 15-30 minutes and then centrifuged at 400 x g for 3 minutes. The cell pellets were washed twice with FACS buffer. The washed cell pellets were resuspended in 1 x PBS + 1% FBS at a concentration of approximately 10 7 cells / ml. Using fluorescence-activated cell sorting, antigen-specific single B cells were sorted into 96-well plates (20 plates per rabbit). The 96-well B cell culture plates of sorted B cells were incubated at 37°C, 5% CO2 for 12 days.

[0366] Screening of single B cell cultures

[0367] On day 8 post-sorting, 15 pL of B cell culture supernatant was collected from each well for antigen-specific ELISA. Briefly, B cell culture supernatant was transferred to a coated CD79b ectodomain (ECD) blocked 384-well plate. Cells were incubated at room temperature for 1 hour and washed 3 times with PBS + 0.05% Tween-20. Secreted antibodies were detected using goat anti-rabbit IgG HRP + TMB substrate. B cell supernatants that met the OD450 cutoff value (>0.5 or 3-fold over pre-immune serum) were then selected. Using FACS, selected cells were (1) counter-screened against CD79b variants with N-terminal deletions (deletion of the first 13 amino acid residues from the N-terminus, SEQ ID NO: 2); (2) screened for cross-species binding against cynomolgus CD79b (SEQ ID NO: 3), and (3) screened against cell surface binding against Daudi cells.

[0368] Supernatants from 40 plate (96-well plate) sorted B-cells were subjected to initial ELISA screening to screen for CD79b specific antibodies. Approximately 230 CD79b antigen specific positive B-cell clones were identified.

[0369] At day 12 post-sort, B-cell culture plates were centrifuged at 400xg for 3 minutes. Supernatants from positive clones (OD greater than the selected cutoff for antigen specific ELISA) were collected and cell pellets were saved in 100 μL DNA / RNA shield (Zymo Cat# R1100-250) in 250 μL PCR tubes. Collected supernatants were subjected to additional testing as described below.

[0370] Screening for CD79b specific antibodies that bind to cell surface expressed CD79b

[0371] CD79b is a member of the B-cell receptor complex. Not all antibody clones that bind CD79b in ELISA are expected to also bind cell surface expressed CD79b due to epitope accessibility. CD79b specific B-cell clones identified by ELISA were subjected to cell surface binding assay with Daudi cells by FACS. Briefly, 50 μl of B-cell supernatant (diluted 1:10 in FACS buffer, lx PBS + 0.5% BSA) was incubated with 50,000 Daudi cells (seeded in 96-well plate) on ice for 1 hour, then washed with 150 μL ice cold FACS buffer. 100 μl of anti-rabbit-PE secondary antibody (Biolegend) was added, mixed and incubated on ice for 30 minutes. Cells were washed 3 times with 150 μL FACS buffer and finally resuspended in 100 μL FACS buffer. 5,000 cells from each stained were collected in a flow cytometer for analysis. Out of approximately 230 ELISA positive B-cell clones, 12 clones showed binding to cell surface CD79b.

[0372] Obtaining VH and VL gene sequences from selected anti-CD79b clones

[0373] DNA fragments encoding the heavy chain variable domain (VH) and light chain variable domain (VL) from the B cell clone were shown to have high cell surface binding affinity to CD79b by 5' RACE (rapid amplification of cDNA ends), TOPO cloning and sequencing.

[0374] Example 2. Generation of chimeric expression constructs

[0375] For expression of the rabbit / human chimeric IgGl antibody, the human IgGl heavy chain constant region (CH1-CH3, SEQ ID NO: 4) and the human Kappa light chain constant region (CL-kappa, SEQ ID NO: 5) were synthesized and cloned into the pcDNA3.4 vector (Invitrogen) separately. The heavy chain cloning vector pcDNA3.4-huIgGl-Hc was digested with EcoRI / NheI for cloning of the VH fragment. The light chain cloning vector pcDNA3.4-huKappa-Lc was digested with EcoRI / BsiWI for cloning of the VL fragment. Recombinant rabbit / human chimeric antibody constructs were generated. Specifically, the VH and VL sequences selected from the rabbit anti-CD79b antibody were obtained by gene synthesis (Integrated DNA Technologies) and ligated with a leader sequence (SEQ ID NO: 6) for Gibson assembly (NEB NEBuilder® HiFi DNA Assembly) at both 5' and 3' ends to generate HC and LC expression plasmids. The assembled plasmids were used to transform competent E. coli (NEB® 5-alpha). The clones with correct sequences were selected according to sequencing results (Elim Biopharm) and cultured in LB medium containing carbenicillin (100 ug / ml). The plasmids were purified (QIAGEN Plasmid Plus Kits), eluted in nuclease-free H2O (Sigma), and stored at -80°C.

[0376] Example 3. Expression and purification of chimeric anti-CD79b antibodies

[0377] Recombinant chimeric antibodies were expressed in CHO cells (ExpiCHO™ Expression System, Gibco) by transfecting the cells with pcDNA3.4-huIgGl-Hc and pcDNA3.4-huKappa-Lc containing the paired VH and VL sequences. ExpiCHO cells were cultured with ExpiCHO Expression Medium and maintained at 0.3 to 6 x 10 6 cells / ml, 37°C, 125 rpm, 5% CO2, and 80% humidity. In 125 ml baffled flasks, 3 x 106 / ml of fresh ExpiCHO cells (6 x 10 6 / ml, viability > 95%, prepared the day before transfection). 1 ml of serum-free medium (OptiPRO™ SFM, Gibco) containing pcDNA3.4-huIgGl-Hc and pcDNA3.4-huKappa-Lc (12 ug of each plasmid) was mixed with 1 ml of OptiPRO™ SFM containing 80 ul of transfection reagent (ExpiFectamine™ CHO reagent, Gibco). The transfection mixture was then added to 25 ml of ExpiCHO cells and incubated at 37°C. The next day, after the addition of 150 ul of ExpiFectamine™ CHO Enhancer, 6 ml of ExpiCHOTM Feed, and 1x Penicillin-Streptomycin (Gibco), the transfection culture was transferred to a 32°C incubator. Cell density and viability of the transfection culture were monitored, and IgGl antibody titers in the culture medium were monitored using a Bio-Layer Interferometry (BLI) instrument with a Protein A biosensor (Gator prime by Gator Bio).

[0378] After 5 days, the culture medium containing secreted IgGl antibodies was collected (centrifuged at 2000g for 10 minutes), filtered (Thermo Scientific™ Nalgene™ Rapid-Flow™ Sterile Disposable Filters) and packed into a gravity flow column (Bio-Rad) using a Protein A resin (TOYOPEARL AF-rProtein Hc-650F). IgGl antibodies were eluted with 3.5 ml of Glycine-HCl (100 mM, pH 2.7), immediately neutralized with 1 M Tris-HCl (pH 8.5), dialyzed against dialysis buffer (1x PBS, pH 7.2) using Thermo Scientific™ Slide-A-Lyzer™ G2 Dialysis Cassettes (20K MWCO), and stored at 4°C. The concentration of purified IgGl antibodies was determined using a NanoDrop™ One / OneC Microvolume UV-Visible Spectrophotometer (Thermo Scientific™), and the quality of IgGl antibodies was checked by SDS-PAGE gels under denaturing and non-denaturing conditions.

[0379] Example 4. Binding affinity of anti-CD79b antibodies to human and cynomolgus CD79b recombinant proteins determined by ELISA and BLI

[0380] Anti-CD79b antibodies were tested for binding affinity to human and cynomolgus CD79b recombinant proteins by ELISA. 1 pg / ml (in PBS buffer) human or cynomolgus CD79b recombinant proteins were coated on ELISA plates overnight. ELISA plates were washed and blocked with blocking buffer (PBS + 1% BSA), then incubated with serially diluted anti-CD79b primary antibodies. Anti-human IgG HRP secondary antibody (Biolegend Cat# 410902) and HRP substrate were used to quantify anti-CD79b antibody binding. ELISA binding affinity of anti-CD79b antibodies to human and cynomolgus CD79b recombinant proteins are shown in Table 1, Figure 1 and Figure 2

[0381] Anti-CD79b antibodies were tested for binding affinity to human CD79b recombinant protein by BLI. Anti-human IgG Fc probe (Gator Bio Catalog #160024) captured 10 pg / ml of anti-CD79b antibodies. Binding and dissociation of serially diluted (146 nM to 0 nM, 2-fold dilution in PBS + 0.05% Tween-20) human CD79b recombinant protein were measured. Absolute kD was determined by applying a 1 : 1 binding model (Global Rmax unlinked). BLI binding affinity of anti-CD79b antibodies to human CD79b recombinant protein are shown in Table 1 and Figure 3 Polatuzumab was used for comparison purposes. For ch44G2, Kon was 3.77E+05 but koff was not detectable according to BLI data. This indicates that ch44G2 has very strong binding affinity to CD79b.

[0382] Table 1. ELISA IC50 (nM) binding of anti-CD79b antibodies to human and cynomolgus CD79b recombinant proteins, and BLI kD (M) binding to human CD79b recombinant protein

[0383] Example 5. Internalization of anti-CD79b antibodies

[0384] ​The internalization of anti-CD79b antibodies was assessed. Approximately 50,000 Ramos cells were incubated with 20ug / ml of labeled anti-CD79b antibodies and incubated at 37°C. At different time points, cells were washed and the presence of anti-CD79b antibody bound to the receptor was detected using an anti-human IgG PE secondary antibody (Jackson Research Catalogue #109-116-170). To analyze, the mean fluorescence intensity (MFI (PE)) of each antibody was normalized to its respective zero time point (100%) and the percentage MFI (PE) reduction over time was plotted. As shown in Figure 4 Figure 6, all screened anti-CD79b antibodies internalized slower than polatuzumab. Among them, ch23D8, ch44G2, ch48H10 and ch57B9 exhibited a much slower internalization process than the other antibodies.

[0385] Example 6. Quantification of CD79b antigen density on tumor cell surface

[0386] To estimate the CD79b antigen expression level on the surface of malignant B tumor cells and normal B cells, malignant B tumor cell lines and PBMCs from two healthy donors were stained with anti-CD79b antibody ch44G2 at saturating concentration for 30 minutes on ice. After washing with PBS, cells were stained with secondary PE-labeled anti-human IgG (Invitrogen, Cat. No: 12-4998-82) for 30 minutes on ice. Cells were then washed with PBS and resuspended in FACS buffer for flow cytometry analysis using Cytek northern lights. Results were analyzed and plotted using GraphPad prism software (version 9.4.1; GraphPad Software Inc.). Quantification of CD79b antigen density on the surface of malignant B tumor cells and normal B cells is shown in Table 2 and Figure 5 Figure 7.

[0387] Table 2. Quantification of CD79b antigen density on the surface of malignant B tumor cells and normal B cells

[0388] Example 7. Malignant B cell line binding assay

[0389] The binding affinity of anti-CD79b antibodies to malignant B cell lines was tested. Polatuzumab and IgGl were used as positive and negative controls, respectively. Malignant B cell lines (BJAB, Ramos, Daudi, SU-DHL-4, and Nalm-6) at 50,000 cells / well in 96-well plates were incubated with anti-CD79b antibodies (ch22D10, ch23D8, ch29C3, ch44G2, ch48H10, ch57B9, and polatuzumab) and IgGl (Biolegend, Cat#: 403502) at different concentrations (from 40 nM serially diluted 1:3) for 30 minutes on ice and washed twice with 200 μΐ PBS. Then the cells were incubated with 100 μΐ anti-human IgGl-PE (Invitrogen, cat: 12-4998-82), 1:1000 dilution, for 30 minutes on ice and washed with 200 ul PBS for 3 times before flow cytometry analysis. As shown in Figures 6-10, anti-CD79b antibodies ch23D8, ch44G2, ch48H10, and ch57B9 showed higher cell surface binding affinity (lower EC50) to BJAB (Figure 6), Ramos (Figure 7), Daudi (Figure 8), SU-DHL-4 (Figure 9), and Nalm-6 (Figure 10) than polatuzumab. The results indicated that ch23D8, ch44G2, ch48H10, and ch57B9 can bind to malignant B cell lines with high and low levels of CD79b antigen density.

[0390] Example 8. Endogenous B cell binding assay

[0391] The binding affinity of anti-CD79b antibodies to endogenous B cells was tested. Polatuzumab and IgG1 controls were used as positive and negative controls, respectively. PBMCs from four donors (Stanford Blood Center) were plated at 200,000 cells / well in 96-well plates with various concentrations (serial 1:5 dilution from 50 nM) of anti-CD79b antibodies (ch23D8, ch44G2, ch48H10, and polatuzumab) and IgG1 (Biolegend, catalog number 403502). The plates were incubated on ice for 30 minutes and washed twice with 200 μl of PBS. The cells were then incubated with 100 µl of a 1:1000 dilution of anti-human IgG1-PE (Invitrogen, catalog number: 12-4998-82) and CD19-BV421 (Biolegend, cat#: 302230, 1:400 dilution) mixture on ice for 30 minutes and washed three times with 200 µl of PBS before flow cytometric analysis. As shown in Figures 11-14, ch44G2, ch48H10, and ch23D8 exhibited higher cell surface binding affinity than polatuzumab in all four different donors.

[0392] Example 9. PBMC Binding Assay in CLL Patients

[0393] To determine the binding affinity of anti-CD79b antibodies to cell surface CD79b on B lymphocytes from patients with chronic lymphocytic leukemia (CLL), a cell-based binding assay was performed. Polatuzumab and an IgG1 control were used as positive and negative controls, respectively. PBMCs from patients with CLL were purchased from Bioscience. FACS analysis showed that 95% of B lymphocytes (CD19+) in the PBMCs were positive. Specifically, 2.5 × 10 4PBMC cells were seeded at 200,000 cells per well of a V-bottom 96-well plate. Then, 50 μΐ of serially diluted anti-CD79b antibodies (ch22D10, ch23D8, ch29C3, ch44G2, ch48H10, ch57B9, or polatuzumab) or IgGl were added to each well. The mixture was incubated on ice for 30 minutes, then washed twice with FACS buffer. Cells were resuspended in 100 μΐ FACS buffer containing PE-conjugated goat anti-human IgG Fc (1:1000) and anti-human CD19 (BV421), and incubated on ice for 30 minutes in the dark. After washing twice with FACS buffer, cells were resuspended in 100 μΐ FACS buffer and analyzed with a Cytek cytometer. As shown in FIGS. 15-16, ch23D8, ch44G2, ch48H10, and ch57B9 exhibited more potent binding to CLL patient B lymphocytes than polatuzumab.

[0394] Example 10. CD79b mAbs bind to both long and short forms of CD79b

[0395] Surface binding of anti-CD79b antibodies to both short and long forms of CD79b was investigated. Polatuzumab was used as a positive control. Approximately 200 million Nalm-6 cells were electroporated with expression plasmids encoding CD79b short form (Nalm-6 + short form) and long form (Nalm-6 + long form), respectively. After 48 hours, cells were stained with selected anti-CD79b antibodies (ch23D8, ch44G2, or polatuzumab) and detected using anti-IgM-APC ch23D8, ch44G2, or polatuzumab. As shown in FIGS. 17A-17B, ch23D8 and ch44G2 had strong binding affinity to both long form CD79b and short form CD79b.

[0396] Example 11. Humanization of anti-CD79b antibodies

[0397] Four rabbit anti-human CD79b monoclonal antibodies, 23D8, 44G2, 48H10, and 57B9, were humanized by grafting the CDRs of the lead antibodies into selected human germline frameworks closest to the rabbit frameworks identified with IgBLAST (https: / / www.ncbi.nlm.nih.gov / igblast / ) and / or IMGT / DomainGapAlig (https: / / www.imgt.org / 3Dstructure-DB / cgi / DomainGapAlign.cgi). Human germline IGHV, IGKV, IGHJ, and IGKJ were selected based on sequence similarity within the framework and CDRs. Some human germline framework residues were back-mutated to the corresponding rabbit residues to maintain canonical loop structures and light / heavy chain interfaces (Padlan Mol. Immunol., 1994, 31:169; Foote and Winter JMB, 1992, 224:487; Padlan Mol. Immunol., 1994, 31:169). Through humanization, hu23D8, hu44G2, hu48H10, and hu57B9 humanized antibodies were generated.

[0398] The thermal stability of the humanized antibody clones was assessed by Nano DSF (Table 3). In ELISA (Fig. 1) and cell lines expressing endogenous CD79b (Fig. 2), the humanized antibodies were confirmed to bind to recombinant human CD79b ECD. Figure 18 ) and cell lines expressing endogenous CD79b ( Figure 19 ) the humanized antibodies were confirmed to bind to recombinant human CD79b ECD.

[0399] The results show that the humanized anti-CD79b antibodies exhibit the same technical effects as the chimeric anti-CD79b antibodies, such as high affinity for CD79b, slow internalization, high binding to malignant B cell lines with high and low CD79b antigen density, high cell surface binding affinity to endogenous B cells, high binding to B lymphocytes of CLL patients, and strong binding affinity to long-form CD79b and short-form CD79b.

[0400] Table 3. Thermal stability of humanized anti-CD79b antibodies

[0401] Other embodiments

[0402] It is to be understood that while the application has been described in conjunction with the detailed description thereof, the foregoing description is meant to illustrate and not to limit the scope of the application. Other aspects, advantages and modifications are within the scope of the following claims.

Claims

1. An antibody or antigen-binding fragment thereof that binds to CD79b (cluster of differentiation 79B), comprising: a heavy chain variable region (VH) comprising complementarity determining regions (CDRs) 1, 2, and 3, wherein the VH CDR1 region comprises an amino acid sequence at least 80% identical to a selected VH CDR1 amino acid sequence, the VH CDR2 region comprises an amino acid sequence at least 80% identical to a selected VH CDR2 amino acid sequence, and the VH CDR3 region comprises an amino acid sequence at least 80% identical to a selected VH CDR3 amino acid sequence; and a light chain variable region (VL) comprising complementarity determining regions (CDRs) 1, 2, and 3, wherein the VL CDR1 region comprises an amino acid sequence that is at least 80% identical to a selected VL CDR1 amino acid sequence, the VL CDR2 region comprises an amino acid sequence that is at least 80% identical to a selected VL CDR2 amino acid sequence, and the VL CDR3 region comprises an amino acid sequence that is at least 80% identical to a selected VL CDR3 amino acid sequence, The above selected VH CDR 1, 2 and 3 amino acid sequence and the selected VL CDR 1, 2 and 3 amino acid sequence are one of the following: (1) The amino acid sequences of the selected VH CDRs 1, 2, and 3 are listed in SEQ ID NOs: 9, 11, and 13, respectively, and the amino acid sequences of the selected VL CDRs 1, 2, and 3 are listed in SEQ ID NOs: 14-16, respectively; (2) The amino acid sequences of the selected VH CDRs 1, 2, and 3 are listed in SEQ ID NOs: 19, 21, and 23, respectively, and the amino acid sequences of the selected VL CDRs 1, 2, and 3 are listed in SEQ ID NOs: 24-26, respectively; (3) The selected VH CDR 1, 2, and 3 amino acid sequences are listed in SEQ ID NOs: 29, 31, and 33, respectively, and the selected VL CDR 1, 2, and 3 amino acid sequences are listed in SEQ ID NOs: 34-36, respectively; (4) The amino acid sequences of the selected VH CDRs 1, 2, and 3 are listed in SEQ ID NOs: 39, 41, and 43, respectively, and the amino acid sequences of the selected VL CDRs 1, 2, and 3 are listed in SEQ ID NOs: 44-46, respectively; (5) The amino acid sequences of the selected VH CDRs 1, 2, and 3 are listed in SEQ ID NOs: 49, 51, and 53, respectively, and the amino acid sequences of the selected VL CDRs 1, 2, and 3 are listed in SEQ ID NOs: 54-56, respectively; (6) The selected VH CDR 1, 2, and 3 amino acid sequences are listed in SEQ ID NOs: 59, 61, and 63, respectively, and the selected VL CDR 1, 2, and 3 amino acid sequences are listed in SEQ ID NOs: 64-66, respectively; (7) The amino acid sequences of the selected VH CDRs 1, 2, and 3 are listed in SEQ ID NOs: 10, 12, and 13, respectively, and the amino acid sequences of the selected VL CDRs 1, 2, and 3 are listed in SEQ ID NOs: 14-16, respectively; (8) The selected VH CDR 1, 2, and 3 amino acid sequences are listed in SEQ ID NOs: 20, 22, and 23, respectively, and the selected VL CDR 1, 2, and 3 amino acid sequences are listed in SEQ ID NOs: 24-26, respectively; (9) The selected VH CDR 1, 2, and 3 amino acid sequences are listed in SEQ ID NOs: 30, 32, and 33, respectively, and the selected VL CDR 1, 2, and 3 amino acid sequences are listed in SEQ ID NOs: 34-36, respectively; (10) The selected VH CDR 1, 2, and 3 amino acid sequences are listed in SEQ ID NOs: 40, 42, and 43, respectively, and the selected VL CDR 1, 2, and 3 amino acid sequences are listed in SEQ ID NOs: 44-46, respectively; (11) The selected VH CDR 1, 2, and 3 amino acid sequences are listed in SEQ ID NOs: 50, 52, and 53, respectively, and the selected VL CDR 1, 2, and 3 amino acid sequences are listed in SEQ ID NOs: 54-56, respectively; and (12) The amino acid sequences of the selected VH CDRs 1, 2, and 3 are listed in SEQ ID NOs: 60, 62, and 63, respectively, and the amino acid sequences of the selected VL CDRs 1, 2, and 3 are listed in SEQ ID NOs: 64-66, respectively.

2. The antibody or antigen-binding fragment thereof according to claim 1, wherein the VH comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 9, 11, and 13, respectively, and the VL comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 14-16, respectively, according to the Kabat definition.

3. The antibody or antigen-binding fragment thereof according to claim 1, wherein the VH comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 19, 21, and 23, respectively, and the VL comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 24-26, respectively, according to the Kabat definition.

4. The antibody or antigen-binding fragment thereof according to claim 1, wherein the VH comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 29, 31, and 33, respectively, and the VL comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 34-36, respectively, according to the Kabat definition.

5. The antibody or antigen-binding fragment thereof according to claim 1, wherein the VH comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 39, 41, and 43, respectively, and the VL comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 44-46, respectively, according to the Kabat definition.

6. The antibody or antigen-binding fragment thereof according to claim 1, wherein the VH comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 49, 41, and 43, respectively, and the VL comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 54-56, respectively, according to the Kabat definition.

7. The antibody or antigen-binding fragment thereof according to claim 1, wherein the VH comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 59, 61, and 63, respectively, and the VL comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 64-66, respectively, according to the Kabat definition.

8. The antibody or antigen-binding fragment thereof according to claim 1, wherein the VH comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 10, 12, and 13, respectively, and the VL comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 14-16, respectively, according to the Chothia definition.

9. The antibody or antigen-binding fragment thereof according to claim 1, wherein the VH comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 20, 22, and 23, respectively, and the VL comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 24-26, respectively, according to the Chothia definition.

10. The antibody or antigen-binding fragment thereof according to claim 1, wherein the VH comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 30, 32, and 33, respectively, and the VL comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 34-36, respectively, according to the Chothia definition.

11. The antibody or antigen-binding fragment thereof according to claim 1, wherein the VH comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 40, 42, and 43, respectively, and the VL comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 44-46, respectively, according to the Chothia definition.

12. The antibody or antigen-binding fragment thereof according to claim 1, wherein the VH comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 50, 52, and 53, respectively, and the VL comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 54-56, respectively, according to the Chothia definition.

13. The antibody or antigen-binding fragment thereof according to claim 1, wherein the VH comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 60, 62, and 63, respectively, and the VL comprises CDRs 1, 2, and 3 having the amino acid sequences shown in SEQ ID NOs: 64-66, respectively, according to the Chothia definition.

14. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 13, wherein the antibody or antigen-binding fragment thereof specifically binds to human, mouse, monkey or dog CD79b.

15. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 14, wherein the antibody or antigen-binding fragment thereof is a humanized antibody or antigen-binding fragment thereof, a single-chain variable fragment (scFv), a one-armed antibody, and / or a multispecific antibody (such as a bispecific antibody). 16 . The antibody or antigen-binding fragment thereof according to claim 1 , wherein the antibody or antigen-binding fragment thereof comprises a human IgG1 constant region, a human IgG2 constant region, or a human IgG4 constant region.

17. A nucleic acid comprising a polynucleotide encoding a polypeptide comprising: (1) an immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs: 9, 11, and 13, respectively, and which binds to CD79b when paired with a light chain variable region comprising the amino acid sequence in SEQ ID NO: 8; (2) an immunoglobulin light chain or fragment thereof comprising a VL comprising complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences set forth in SEQ ID NOs: 14-16, respectively, and which binds to CD79b when paired with a heavy chain variable region comprising the amino acid sequence in SEQ ID NO: 7; (3) an immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs: 19, 21, and 23, respectively, and which binds to CD79b when paired with a light chain variable region comprising the amino acid sequence in SEQ ID NO: 18; (4) an immunoglobulin light chain or fragment thereof comprising a VL comprising complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences set forth in SEQ ID NOs: 24-26, respectively, and which binds to CD79b when paired with a heavy chain variable region comprising the amino acid sequence in SEQ ID NO: 17; (5) an immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs: 29, 31, and 33, respectively, and which binds to CD79b when paired with a light chain variable region comprising the amino acid sequence in SEQ ID NO: 28; (6) an immunoglobulin light chain or fragment thereof comprising a VL comprising complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences set forth in SEQ ID NOs: 34-36, respectively, and which binds to CD79b when paired with a heavy chain variable region comprising the amino acid sequence in SEQ ID NO: 27; (7) an immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs: 39, 41, and 43, respectively, and which binds to CD79b when paired with a light chain variable region comprising the amino acid sequence in SEQ ID NO: 38; (8) an immunoglobulin light chain or fragment thereof comprising a VL comprising complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences set forth in SEQ ID NOs: 44-46, respectively, and which binds to CD79b when paired with a heavy chain variable region comprising the amino acid sequence in SEQ ID NO: 37; (9) An immunoglobulin heavy chain or fragment thereof comprising a VH, wherein the VH comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs: 49, 51, and 53, respectively, and binds to CD79b when the VH is paired with a light chain variable region comprising the amino acid sequence in SEQ ID NO: 48; (10) An immunoglobulin light chain or fragment thereof comprising a VL, wherein the VL comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs: 54-56, respectively, and binds to CD79b when the VL is paired with a heavy chain variable region comprising the amino acid sequence in SEQ ID NO: 47; (11) An immunoglobulin heavy chain or fragment thereof comprising a VH, wherein the VH comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs: 59, 61, and 63, respectively, and binds to CD79b when the VH is paired with a heavy chain variable region comprising the amino acid sequence in SEQ ID NO: NO:58, wherein the light chain variable region comprises an amino acid sequence as set forth in SEQ ID NO:58, and binds to CD79b; (12) an immunoglobulin light chain or fragment thereof comprising a VL, wherein the VL comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NO:64-66, respectively, and binds to CD79b when the VL is paired with a heavy chain variable region comprising the amino acid sequence as set forth in SEQ ID NO:57; (13) an immunoglobulin heavy chain or fragment thereof comprising a VH, wherein the VH comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NO:10, 12, and 13, respectively, and binds to CD79b when the VH is paired with a light chain variable region comprising the amino acid sequence as set forth in SEQ ID NO:8; (14) an immunoglobulin heavy chain or fragment thereof comprising a VH, wherein the VH comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NO:20, 22, and 23, respectively, and binds to CD79b when the VH is paired with a light chain variable region comprising the amino acid sequence as set forth in SEQ ID NO: NO:18, wherein the light chain variable region comprises an amino acid sequence as set forth in SEQ ID NO:18, and binds to CD79b; (15) an immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NO:30, 32, and 33, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region comprising the amino acid sequence as set forth in SEQ ID NO:28; (16) an immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NO:40, 42, and 43, respectively, and wherein the VH binds to CD79b when paired with a light chain variable region comprising the amino acid sequence as set forth in SEQ ID NO:38;(17) An immunoglobulin heavy chain or fragment thereof comprising a VH, wherein the VH comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs: 50, 52, and 53, respectively, and binds to CD79b when the VH is paired with a light chain variable region comprising the amino acid sequence in SEQ ID NO: 48; (18) An immunoglobulin heavy chain or fragment thereof comprising a VH, wherein the VH comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs: 60, 62, and 63, respectively, and binds to CD79b when the VH is paired with a light chain variable region comprising the amino acid sequence in SEQ ID NO: 58; (19) An immunoglobulin heavy chain or fragment thereof comprising a VH, wherein the VH comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs: 19, 21, and 23, respectively, and binds to CD79b when the VH is paired with a light chain variable region comprising the amino acid sequence in SEQ ID NO: NO:70, binds to CD79b; (20) an immunoglobulin light chain or fragment thereof comprising a VL, wherein the VL comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs: 24-26, respectively, and when the VL is paired with a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 69, binds to CD79b; (21) an immunoglobulin heavy chain or fragment thereof comprising a VH, wherein the VH comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs: 20, 22, and 23, respectively, and when the VH is paired with a light chain variable region comprising the amino acid sequence of SEQ ID NO: 70, binds to CD79b; (22) an immunoglobulin heavy chain or fragment thereof comprising a VH, wherein the VH comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs: 39, 41, and 43, respectively, and when the VH is paired with a light chain variable region comprising the amino acid sequence of SEQ ID NO: NO:72, wherein the light chain variable region thereof binds to CD79b; (23) an immunoglobulin light chain or fragment thereof comprising a VL, wherein the VL comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs:44-46, respectively, and binds to CD79b when the VL is paired with a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:71; (24) an immunoglobulin heavy chain or fragment thereof comprising a VH, wherein the VH comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs:40, 42, and 43, respectively, and binds to CD79b when the VH is paired with a light chain variable region comprising the amino acid sequence of SEQ ID NO:72;(25) An immunoglobulin heavy chain or fragment thereof comprising a VH, wherein the VH comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs: 49, 51, and 53, respectively, and binds to CD79b when the VH is paired with a light chain variable region comprising the amino acid sequence in SEQ ID NO: 73; (26) An immunoglobulin light chain or fragment thereof comprising a VL, wherein the VL comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs: 54-56, respectively, and binds to CD79b when the VL is paired with a heavy chain variable region comprising the amino acid sequence in SEQ ID NO: 74; (27) An immunoglobulin heavy chain or fragment thereof comprising a VH, wherein the VH comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences listed in SEQ ID NOs: 50, 52, and 53, respectively, and binds to CD79b when the VH is paired with a heavy chain variable region comprising the amino acid sequence in SEQ ID NO: NO:73, wherein the VH comprises complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences of SEQ ID NOs: 59, 61, and 63, respectively, and binds to CD79b when paired with a light chain variable region comprising the amino acid sequence of SEQ ID NO: 76; (29) an immunoglobulin light chain or fragment thereof comprising a VL comprising complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences of SEQ ID NOs: 64-66, respectively, and binds to CD79b when paired with a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 75; (30) an immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity determining regions (CDRs) 1, 2, and 3 of the amino acid sequences of SEQ ID NOs: 60, 62, and 63, respectively, and binds to CD79b when paired with a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: The light chain variable region of the amino acid sequence in NO:76 binds to CD79b when paired.

18. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or fragment thereof, wherein the immunoglobulin light chain or fragment thereof comprises a VL comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 14-16.

19. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or a fragment thereof, wherein the immunoglobulin light chain or fragment thereof comprises a VL comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 24-26.

20. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or fragment thereof, wherein the immunoglobulin light chain or fragment thereof comprises a VL comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 34-36.

21. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or fragment thereof, wherein the immunoglobulin light chain or fragment thereof comprises a VL comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 44-46.

22. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or fragment thereof, wherein the immunoglobulin light chain or fragment thereof comprises a VL comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 54-56.

23. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or fragment thereof, wherein the immunoglobulin light chain or fragment thereof comprises a VL comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 64-66.

24. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or fragment thereof, a VH comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 9, 11, and 13.

25. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or fragment thereof, a VH comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 21, and 23.

26. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or fragment thereof, a VH comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 29, 31, and 3.

27. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or fragment thereof, a VH comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 39, 41, and 43.

28. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or fragment thereof, a VH comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 49, 51, and 53.

29. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or a fragment thereof, a VH comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 59, 61, and 63.

30. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or a fragment thereof, wherein the immunoglobulin heavy chain or fragment thereof comprises a VH comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 10, 12, and 13.

31. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or fragment thereof, a VH comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 20, 22, and 23.

32. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or fragment thereof, a VH comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 30, 32, and 3.

33. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or fragment thereof, a VH comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 40, 42, and 43.

34. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or fragment thereof, a VH comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 50, 52, and 53.

35. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or fragment thereof, a VH comprising CDRs 1, 2, and 3, wherein the CDRs 1, 2, and 3 comprise the amino acid sequences set forth in SEQ ID NOs: 60, 62, and 63.

36. The nucleic acid according to any one of claims 17 to 35, wherein the VH specifically binds to human, mouse, monkey or dog CD79b when paired with the VL, or the VL specifically binds to human, mouse, monkey or dog CD79b when paired with the VH.

37. The nucleic acid of any one of claims 17 to 36, wherein the immunoglobulin heavy chain or fragment thereof comprises a human immunoglobulin heavy chain fragment (e.g., human IgG1 heavy chain CH1, CH2 and / or CH3, human IgG2 heavy chain CH1, CH2 and / or CH3, or human IgG4 heavy chain CH1, CH2 and / or CH3), and the immunoglobulin light chain or fragment thereof comprises a human immunoglobulin light chain constant region.

38. The nucleic acid of any one of claims 17-37, wherein the nucleic acid encodes a single-chain variable fragment (scFv), a one-armed antibody, a multispecific antibody (e.g., a bispecific antibody), or a chimeric antigen receptor (CAR).

39. The nucleic acid of any one of claims 17-38, wherein the nucleic acid is cDNA.

40. A vector comprising one or more nucleic acids according to any one of claims 17-39.

41. A vector comprising two of the nucleic acids of any one of claims 17-39, wherein the vector jointly encodes and binds to the VL and VH regions of CD79b.

42. A pair of vectors, wherein each vector comprises one of the nucleic acids of any one of claims 17-39, wherein the pair of vectors jointly encode and bind to the VL region and VH region of CD79b.

43. A cell comprising the vector of claim 41 or 41, or the vector pair of claim 42.

44. The cell of claim 43, wherein the cell is a CHO cell.

45. A cell comprising one or more nucleic acids according to any one of claims 17-39.

46. ​​A cell comprising two nucleic acids of any one of claims 17-39.

47. The cell of claim 46, wherein the two nucleic acids together encode and bind to the VL and VH regions of CD79b.

48. A method for producing an antibody or an antigen-binding fragment thereof, the method comprising (a) culturing the cell of any one of claims 43-47 under conditions sufficient for the cell to produce the antibody or antigen-binding fragment; and (b) collecting the antibodies or antigen-binding fragments produced by the cells.

49. An antibody or antigen-binding fragment thereof that binds to CD79b, comprising a heavy chain variable region (VH) comprising an amino acid sequence at least 90% identical to a selected VH sequence, and a light chain variable region (VL) comprising an amino acid sequence at least 90% identical to a selected VL sequence, wherein the selected VH sequence and the selected VL sequence are one of the following sequences: (1) The selected VH sequence is SEQ ID NO: 7, and the selected VL sequence is SEQ ID NO: 8; (2) the selected VH sequence is SEQ ID NO: 17 or 69, and the selected VL sequence is SEQ ID NO: 18 or 70; (3) The selected VH sequence is SEQ ID NO: 27, and the selected VL sequence is SEQ ID NO: 28; (4) the selected VH sequence is SEQ ID NO: 37 or 71, and the selected VL sequence is SEQ ID NO: 38 or 72; (5) the selected VH sequence is SEQ ID NO: 47 or 73, and the selected VL sequence is SEQ ID NO: 48 or 74; and (6) The selected VH sequence is SEQ ID NO: 57 or 75, and the selected VL sequence is SEQ ID NO: 58 or 76.

50. The antibody or antigen-binding fragment thereof of claim 49, wherein the VH comprises the sequence of SEQ ID NO: 7 and the VL comprises the sequence of SEQ ID NO:

8.

51. The antibody or antigen-binding fragment thereof of claim 49, wherein the VH comprises the sequence of SEQ ID NO: 17 and the VL comprises the sequence of SEQ ID NO:

18.

52. The antibody or antigen-binding fragment thereof of claim 49, wherein the VH comprises the sequence of SEQ ID NO: 27 and the VL comprises the sequence of SEQ ID NO:

28.

53. The antibody or antigen-binding fragment thereof of claim 49, wherein the VH comprises the sequence of SEQ ID NO: 37 and the VL comprises the sequence of SEQ ID NO:

38.

54. The antibody or antigen-binding fragment thereof of claim 49, wherein the VH comprises the sequence of SEQ ID NO: 47 and the VL comprises the sequence of SEQ ID NO:

48.

55. The antibody or antigen-binding fragment thereof of claim 49, wherein the VH comprises the sequence of SEQ ID NO: 57 and the VL comprises the sequence of SEQ ID NO:

58.

56. The antibody or antigen-binding fragment thereof of claim 49, wherein the VH comprises the sequence of SEQ ID NO: 69 and the VL comprises the sequence of SEQ ID NO:

70.

57. The antibody or antigen-binding fragment thereof of claim 49, wherein the VH comprises the sequence of SEQ ID NO: 71 and the VL comprises the sequence of SEQ ID NO:

72.

58. The antibody or antigen-binding fragment thereof of claim 49, wherein the VH comprises the sequence of SEQ ID NO: 73 and the VL comprises the sequence of SEQ ID NO:

74.

59. The antibody or antigen-binding fragment thereof of claim 49, wherein the VH comprises the sequence of SEQ ID NO: 75 and the VL comprises the sequence of SEQ ID NO:

76.

60. An antibody or antigen-binding fragment thereof that binds to CD79b, comprising a heavy chain variable region (VH) comprising a VHCDR1, VH CDR2, and VH CDR3 identical to the VH CDR1, VH CDR2, and VH CDR3 of a selected VH sequence; and a light chain variable region (VL) comprising a VL CDR1, VL CDR2, and VL CDR3 identical to the VL CDR1, VL CDR2, and VL CDR3 of a selected VL sequence, wherein the selected VH sequence and the selected VL sequence are one of the following sequences: (1) The selected VH sequence is SEQ ID NO: 7, and the selected VL sequence is SEQ ID NO: 8; (2) the selected VH sequence is SEQ ID NO: 17 or 69, and the selected VL sequence is SEQ ID NO: 18 or 70; (3) The selected VH sequence is SEQ ID NO: 27, and the selected VL sequence is SEQ ID NO: 28; (4) the selected VH sequence is SEQ ID NO: 37 or 71, and the selected VL sequence is SEQ ID NO: 38 or 72; (5) the selected VH sequence is SEQ ID NO: 47 or 73, and the selected VL sequence is SEQ ID NO: 48 or 74; and (6) The selected VH sequence is SEQ ID NO: 57 or 75, and the selected VL sequence is SEQ ID NO: 58 or 76.

61. The antibody or antigen-binding fragment thereof according to any one of claims 49-60, wherein the antibody or antigen-binding fragment thereof specifically binds to human, mouse, monkey or dog CD79b.

62. The antibody or antigen-binding fragment thereof according to any one of claims 49-61, wherein the antibody or antigen-binding fragment thereof is a humanized antibody or antigen-binding fragment thereof, a chimeric antibody, a single-chain variable fragment (scFv), a one-armed antibody, and / or a multispecific antibody (such as a bispecific antibody).

63. The antibody or antigen-binding fragment thereof according to any one of claims 49 to 62, wherein the antibody or antigen-binding fragment thereof comprises human IgG1 Fc, human IgG2 Fc or human IgG4 Fc.

64. An antibody or antigen-binding fragment thereof that cross-competes with the antibody or antigen-binding fragment thereof of any one of claims 1-16 and 49-63.

65. The antibody or antigen-binding fragment thereof according to any one of claims 1-16 and 49-64, wherein the antibody or antigen-binding fragment thereof comprises a fragment crystallizable region (Fc region).

66. A chimeric antigen receptor (CAR) comprising the antibody or antigen-binding fragment thereof of any one of claims 1-16 and 49-64.

67. An antibody-drug conjugate comprising the antibody or antigen-binding fragment thereof of any one of claims 1-16 and 49-65 covalently bound to a therapeutic agent.

68. The antibody drug conjugate of claim 67, wherein the therapeutic agent is a cytotoxic agent or a cytostatic agent.

69. A method of treating a subject having cancer, the method comprising administering to the subject a therapeutically effective amount of a composition comprising the antibody or antigen-binding fragment thereof of any one of claims 1-16 and 49-65, the CAR of claim 66, or the antibody-drug conjugate of claim 67 or 68.

70. The method of claim 69, wherein the cancer is lymphoma, leukemia, breast cancer, gastric cancer, pancreatic cancer, prostate cancer, cervical cancer, endometrial cancer, ovarian cancer, or urothelial cancer.

71. The method of claim 69, wherein the cancer is non-Hodgkin lymphoma (NHL), diffuse large B-cell lymphoma (DLBCL), B acute lymphoblastic leukemia (B-ALL), chronic lymphocytic leukemia (CLL), B-cell prolymphocytic leukemia (PLL), splenic lymphoma with villous lymphocytes (SLVL), hairy cell leukemia (HCL), follicular lymphoma (FL), or mantle cell lymphoma (MCL).

72. The method of claim 69, wherein the subject is further treated with an effective amount of an anti-4-1BB antibody, an anti-OX40 antibody, an anti-PD-1 antibody, an anti-PD-L1 antibody, an anti-CTLA4 antibody, an anti-CD40 antibody, a BTK inhibitor, or a BCL2 inhibitor.

73. A method for reducing tumor growth rate, the method comprising The tumor cells are contacted with an effective amount of a composition comprising the antibody or antigen-binding fragment thereof of any one of claims 1-16 and 49-65, the CAR of claim 66, or the antibody-drug conjugate of claim 67 or 68.

74. A method for killing tumor cells, the method comprising The tumor cells are contacted with an effective amount of a composition comprising the antibody or antigen-binding fragment thereof of any one of claims 1-16 and 49-65, the CAR of claim 66, or the antibody-drug conjugate of claim 67 or 68.

75. A method of enhancing an immune response in a subject, the method comprising An effective amount of a composition comprising the antibody or antigen-binding fragment thereof of any one of claims 1-16 and 49-65, the CAR of claim 66, or the antibody-drug conjugate of claim 67 or 68 is administered to the subject.

76. A method for treating a subject having an autoimmune disease, the method comprising administering to the subject a therapeutically effective amount of a composition comprising the antibody or antigen-binding fragment thereof of any one of claims 1-16 and 49-65, the CAR of claim 66, or the antibody-drug conjugate of claim 67 or 68.

77. The method of claim 76, wherein the autoimmune disease is selected from the group consisting of rheumatoid arthritis, psoriasis, multiple sclerosis, immune thrombocytopenic purpura, myasthenia gravis, neuromyelitis optica, IgG4-related disease, lupus, systemic lupus erythematosus, lupus nephritis, giant cell arteritis, Takayasu's disease, cold agglutinin disease, febrile autoimmune hemolytic anemia, and antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, granulomatosis with polyangiitis (GPA) (Wegener's granulomatosis), microscopic polyangiitis (MPA), inflammatory bowel disease (IBD), and autoreactive pancreatitis.

78. The method of claim 76, wherein the autoimmune disease is multiple sclerosis, lupus, systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease (IBD), autoreactive pancreatitis, lupus nephritis.

79. A pharmaceutical composition comprising the antibody or antigen-binding fragment thereof according to any one of claims 1-16 and 49-65, and a pharmaceutically acceptable carrier.

80. A pharmaceutical composition comprising the antibody drug conjugate of claim 67 or 68 and a pharmaceutically acceptable carrier.

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