Anti-CD79b antibodies and uses thereof

Abstract

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

Description

[Technical Field]

[0001] The present disclosure relates to anti-CD79b (cluster of differentiation 79B) antibodies, antigen-binding fragments thereof, antibody-drug conjugates (ADCs) derived therefrom, and uses thereof. [Background technology]

[0002] CD79 is a signaling component of the B cell receptor and functions as a covalent heterodimer containing CD79a and CD79b. CD79b contains an extracellular immunoglobulin (Ig) domain, a transmembrane domain, an intracellular signaling domain, and an immunoreceptor tyrosine-based activation motif (ITAM) domain. CD79b expression has been detected on the surface of nearly all non-Hodgkin's lymphoma (NHL) and in patients with acute lymphoblastic leukemia (ALL) and chronic lymphocytic leukemia (CLL).

[0003] CD79b is an attractive therapeutic target for B cell malignancies for several reasons. First, this receptor is not only widely expressed in B cell malignancies, but its expression remains unchanged after loss of CD19 or CD20, making it a prominent alternative for targeted therapy over CD19- or CD20-targeted therapy. Second, when the B cell receptor is crosslinked, it is targeted to the major histocompatibility complex class II compartment, a lysosome-like compartment, as part of class II antigen presentation by B cells.

[0004] Given the important role of CD79b in cancer, there is a need to develop therapeutic agents that target CD79b. Summary of the Invention

[0005] The present disclosure relates to anti-CD79b antibodies, antigen-binding fragments thereof, and uses thereof.

[0006] In one aspect, the present disclosure provides an antibody or antigen-binding fragment thereof that binds to CD79b (cluster of differentiation 79B), 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 amino acid sequence, and the VH CDR3 region comprises an amino acid sequence that is at least 80% identical to a selected VH CDR3 amino acid sequence; a light chain variable region (VL) comprising CDR1, 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 selected VH CDR1, 2, and 3 amino acid sequences and the selected VL CDR1, 2, and 3 amino acid sequences are (1) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 9, 11, and 13, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 14 to 16, respectively; (2) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 19, 21, and 23, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 24 to 26, respectively; (3) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 29, 31, and 33, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 34 to 36, respectively; (4) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 39, 41, and 43, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 44 to 46, respectively; (5) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 49, 51, and 53, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 54 to 56, respectively; (6) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 59, 61, and 63, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 64 to 66, respectively; (7) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 10, 12, and 13, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 14 to 16, respectively; (8) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 20, 22, and 23, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 24 to 26, respectively; (9) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 30, 32, and 33, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 34 to 36, respectively; (10) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 40, 42, and 43, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 44 to 46, respectively; (11) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 50, 52, and 53, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 54 to 56, respectively; and (12) The antibody or antigen-binding fragment thereof, wherein the selected VH CDR1, 2, and 3 amino acid sequences are set forth in SEQ ID NOs: 60, 62, and 63, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are set forth in SEQ ID NOs: 64 to 66, respectively.

[0007] In some embodiments, according to the Kabat definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 9, 11, and 13, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 14 to 16, respectively.

[0008] In some embodiments, according to the Kabat definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 19, 21, and 23, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 24 to 26, respectively.

[0009] In some embodiments, according to the Kabat definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 29, 31, and 33, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 34 to 36, respectively.

[0010] In some embodiments, according to the Kabat definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 39, 41, and 43, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 44 to 46, respectively.

[0011] In some embodiments, according to the Kabat definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 49, 51, and 53, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 54 to 56, respectively.

[0012] In some embodiments, according to the Kabat definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 59, 61, and 63, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 64 to 66, respectively.

[0013] In some embodiments, according to the Chothia definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 10, 12, and 13, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 14 to 16, respectively.

[0014] In some embodiments, according to the Chothia definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 20, 22, and 23, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 24 to 26, respectively.

[0015] In some embodiments, according to the Chothia definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 30, 32, and 33, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 34 to 36, respectively.

[0016] In some embodiments, according to the Chothia definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 40, 42, and 43, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 44 to 46, respectively.

[0017] In some embodiments, according to the Chothia definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 50, 52, and 53, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 54 to 56, respectively.

[0018] In some embodiments, according to the Chothia definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 60, 62, and 63, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 64 to 66, respectively.

[0019] In some embodiments, the antibody or antigen-binding fragment thereof specifically binds to human, mouse, monkey, or canine CD79b.

[0020] 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-arm antibody, and / or a multispecific antibody (e.g., a bispecific antibody).

[0021] In some embodiments, the antibody or antigen-binding fragment thereof comprises a human IgG1 constant region, a human IgG2 constant region, or a human IgG4 constant region.

[0022] In one aspect, the disclosure provides a nucleic acid comprising a polynucleotide encoding a polypeptide, said polypeptide comprising: (1) an immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 9, 11, and 13, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 8; and (2) an immunoglobulin light chain or fragment thereof comprising a VL comprising complementarity-determining regions (CDRs) 1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 14 to 16, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 7; and (3) an immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 19, 21, and 23, respectively, wherein the immunoglobulin heavy chain or fragment thereof binds to CD79b when the VH is paired with a light chain variable region (VL) comprising the amino acid sequence set forth 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 each comprising the amino acid sequences set forth in SEQ ID NOs: 24 to 26, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 17; and (5) an immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 29, 31, and 33, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 28; and (6) An immunoglobulin light chain or a fragment thereof comprising a VL comprising CDR1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 34 to 36, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 27; and (7) an immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 39, 41, and 43, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 38; and (8) An immunoglobulin light chain or a fragment thereof comprising a VL comprising CDR1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 44 to 46, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 37; and (9) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 49, 51, and 53, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 48; and (10) An immunoglobulin light chain or a fragment thereof comprising a VL comprising CDR1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 54 to 56, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 47; and (11) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 59, 61, and 63, respectively, wherein the immunoglobulin heavy chain or fragment thereof binds to CD79b when the VH is paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 58; (12) An immunoglobulin light chain or a fragment thereof comprising a VL comprising CDR1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 64 to 66, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 57; and (13) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 10, 12, and 13, respectively, wherein the immunoglobulin heavy chain or fragment thereof binds to CD79b when the VH is paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 8; (14) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 20, 22, and 23, respectively, wherein the immunoglobulin heavy chain or fragment thereof binds to CD79b when the VH is paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 18; (15) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 30, 32, and 33, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 28; and (16) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 40, 42, and 43, respectively, wherein the immunoglobulin heavy chain or fragment thereof binds to CD79b when the VH is paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 38; (17) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 50, 52, and 53, respectively, wherein the immunoglobulin heavy chain or fragment thereof binds to CD79b when the VH is paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 48; (18) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 60, 62, and 63, respectively, wherein the immunoglobulin heavy chain or fragment thereof binds to CD79b when the VH is paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 58; (19) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 19, 21, and 23, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 70; and (20) An immunoglobulin light chain or fragment thereof comprising a VL comprising complementarity-determining regions (CDRs) 1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 24 to 26, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 69; and (21) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 20, 22, and 23, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 70; and (22) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 39, 41, and 43, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 72; and (23) An immunoglobulin light chain or a fragment thereof comprising a VL comprising CDR1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 44 to 46, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 71; and (24) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 40, 42, and 43, respectively, wherein the immunoglobulin heavy chain or fragment thereof binds to CD79b when the VH is paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 72; (25) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 49, 51, and 53, respectively, wherein the immunoglobulin heavy chain or fragment thereof binds to CD79b when the VH is paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 73; (26) An immunoglobulin light chain or a fragment thereof comprising a VL comprising CDR1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 54 to 56, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 74; and (27) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 50, 52, and 53, respectively, wherein the immunoglobulin heavy chain or fragment thereof binds to CD79b when the VH is paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 73; (28) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 59, 61, and 63, respectively, wherein the immunoglobulin heavy chain or fragment thereof binds to CD79b when the VH is paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 76; (29) An immunoglobulin light chain or a fragment thereof comprising a VL comprising CDR1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 64 to 66, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 75; and (30) A nucleic acid comprising an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 60, 62, and 63, respectively, wherein the immunoglobulin heavy chain or a fragment thereof binds to CD79b when the VH is paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 76.

[0023] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or a fragment thereof comprising a VL comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 14 to 16, respectively.

[0024] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or a fragment thereof comprising a VL comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 24 to 26, respectively.

[0025] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or a fragment thereof comprising a VL comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 34 to 36, respectively.

[0026] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or a fragment thereof comprising a VL comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 44 to 46, respectively.

[0027] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or a fragment thereof comprising a VL comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 54 to 56, respectively.

[0028] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin light chain or a fragment thereof comprising a VL comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 64 to 66, respectively.

[0029] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 9, 11, and 13, respectively.

[0030] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 19, 21, and 23, respectively.

[0031] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 29, 31, and 33, respectively.

[0032] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 39, 41, and 43, respectively.

[0033] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 49, 51, and 53, respectively.

[0034] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 59, 61, and 63, respectively.

[0035] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 10, 12, and 13, respectively.

[0036] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 20, 22, and 23, respectively.

[0037] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 30, 32, and 33, respectively.

[0038] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 40, 42, and 43, respectively.

[0039] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 50, 52, and 53, respectively.

[0040] In some embodiments, the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 60, 62, and 63, respectively.

[0041] In some embodiments, the VH, when paired with a VL, specifically binds human, mouse, monkey, or dog CD79b, or the VL, when paired with a VH, specifically binds human, mouse, monkey, or dog CD79b.

[0042] In some embodiments, the immunoglobulin heavy chain or fragment thereof comprises a human immunoglobulin heavy chain fragment (e.g., a human IgG1 heavy chain CH1, CH2, and / or CH3, a human IgG2 heavy chain CH1, CH2, and / or CH3, or a 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.

[0043] In some embodiments, the nucleic acid encodes a single-chain variable fragment (scFv), a one-arm antibody, a multispecific antibody (e.g., a bispecific antibody), or a chimeric antigen receptor (CAR).

[0044] In some embodiments, the nucleic acid is cDNA.

[0045] In one aspect, the present disclosure relates to a vector comprising one or more of the nucleic acids described herein.

[0046] In one aspect, the disclosure relates to a vector comprising two of the nucleic acids described herein, wherein the vector encodes a VL region and a VH region that together bind to CD79b.

[0047] In one aspect, the disclosure relates to a pair of vectors, each comprising one of the nucleic acids described herein, that together encode a VL region and a VH region that both bind to CD79b.

[0048] In one aspect, the disclosure relates to a cell comprising a vector described herein or a pair of vectors described herein.

[0049] In some embodiments, the cells are CHO cells.

[0050] In one aspect, the present disclosure relates to a cell comprising one or more of the nucleic acids described herein.

[0051] In one aspect, the disclosure relates to a cell comprising two of the nucleic acids described herein.

[0052] In some embodiments, the two nucleic acids encode both a VL region and a VH region that both bind CD79b.

[0053] In one aspect, the disclosure provides a method of producing an antibody or antigen-binding fragment thereof, comprising: (a) culturing a cell described herein under conditions sufficient for said cell to produce said antibody or said antigen-binding fragment; (b) harvesting the antibody or antigen-binding fragment produced by the cell.

[0054] In one aspect, the present disclosure provides an antibody or antigen-binding fragment thereof that binds to CD79b, a heavy chain variable region (VH) comprising an amino acid sequence that is at least 90% identical to a selected VH sequence, and a light chain variable region (VL) comprising 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 (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 antibody or antigen-binding fragment thereof, wherein the selected VH sequence is SEQ ID NO: 57 or 75, and the selected VL sequence is SEQ ID NO: 58 or 76.

[0055] In some embodiments, the VH comprises the sequence of SEQ ID NO:7 and the VL comprises the sequence of SEQ ID NO:8.

[0056] In some embodiments, the VH comprises the sequence of SEQ ID NO:17 and the VL comprises the sequence of SEQ ID NO:18.

[0057] In some embodiments, the VH comprises the sequence of SEQ ID NO:27 and the VL comprises the sequence of SEQ ID NO:28.

[0058] In some embodiments, the VH comprises the sequence of SEQ ID NO:37 and the VL comprises the sequence of SEQ ID NO:38.

[0059] In some embodiments, the VH comprises the sequence of SEQ ID NO:47 and the VL comprises the sequence of SEQ ID NO:48.

[0060] In some embodiments, the VH comprises the sequence of SEQ ID NO:57 and the VL comprises the sequence of SEQ ID NO:58.

[0061] In some embodiments, the VH comprises the sequence of SEQ ID NO:69 and the VL comprises the sequence of SEQ ID NO:70.

[0062] In some embodiments, the VH comprises the sequence of SEQ ID NO:71 and the VL comprises the sequence of SEQ ID NO:72.

[0063] In some embodiments, the VH comprises the sequence of SEQ ID NO:73 and the VL comprises the sequence of SEQ ID NO:74.

[0064] In some embodiments, the VH comprises the sequence of SEQ ID NO:75 and the VL comprises the sequence of SEQ ID NO:76.

[0065] In one aspect, the present disclosure provides an antibody or antigen-binding fragment thereof that binds to CD79b, a heavy chain variable region (VH) comprising a VH CDR1, a VH CDR2, and a VH CDR3 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 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 (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 antibody or antigen-binding fragment thereof, wherein the selected VH sequence is SEQ ID NO: 57 or 75, and the selected VL sequence is SEQ ID NO: 58 or 76.

[0066] In some embodiments, the antibody or antigen-binding fragment thereof specifically binds to human, mouse, monkey, or canine CD79b.

[0067] 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-arm antibody, and / or a multispecific antibody (e.g., a bispecific antibody).

[0068] In some embodiments, the antibody or antigen-binding fragment comprises a human IgG1 Fc, a human IgG2 Fc, or a human IgG4 Fc.

[0069] In one aspect, the present disclosure relates to antibodies or antigen-binding fragments thereof that cross-compete with the antibodies or antigen-binding fragments thereof described herein.

[0070] In some embodiments, the antibody or antigen-binding fragment thereof comprises a fragment crystallizable region (Fc region).

[0071] In one aspect, the present disclosure relates to a chimeric antigen receptor (CAR) comprising an antibody or antigen-binding fragment thereof described herein.

[0072] In one aspect, the present disclosure relates to an antibody drug conjugate comprising an antibody or antigen-binding fragment thereof described herein covalently attached to a therapeutic agent.

[0073] In some embodiments, the therapeutic agent is a cytotoxic or cytostatic agent.

[0074] In one aspect, the disclosure relates to a method of treating a subject having cancer, the method comprising administering to the subject 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.

[0075] 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.

[0076] In some embodiments, the cancer is non-Hodgkin's 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).

[0077] 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-CTLA4 antibody, or an anti-CD40 antibody.

[0078] In one aspect, the present disclosure relates to a method of reducing the rate of tumor growth, comprising contacting tumor cells 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.

[0079] In one aspect, the disclosure relates to a method of killing a tumor cell, the method comprising contacting the 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.

[0080] In one aspect, the present disclosure relates to a method of increasing an immune response in a subject, 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.

[0081] In one aspect, the 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.

[0082] 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 arteritis, cold agglutinin disease, warm autoimmune hemolytic anemia, and antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, granulomatosis with polyangiitis (GPA) (Wegener's granulomatosis), microscopic polyangiitis (MPA), inflammatory bowel disease (IBD), or autoreactive pancreatitis.

[0083] In some embodiments, the autoimmune disease is multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease (IBD), or autoreactive pancreatitis.

[0084] 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.

[0085] In one aspect, the present disclosure relates to a pharmaceutical composition comprising an antibody drug conjugate described herein and a pharmaceutically acceptable carrier.

[0086] As used herein, the term "cancer" refers to cells capable of autonomous growth. Examples of such cells include cells with an abnormal state or condition characterized by rapidly proliferating cell growth. The term is intended to include carcinomas, e.g., tumors, oncogenic processes, metastatic tissues, and malignantly transformed cells, tissues, or organs, regardless of histopathological type or stage of invasiveness. It also includes malignant tumors of various organ systems, such as the respiratory, cardiovascular, renal, reproductive, hematological, nervous, hepatic, gastrointestinal, and endocrine systems, as well as adenocarcinomas, including most colon, renal cell, prostate, and / or testicular tumors, non-small cell lung cancer, and small intestine cancer. "Spontaneously occurring" cancers include any cancer other than those experimentally induced by the implantation of cancer cells into a subject, including, for example, spontaneously occurring cancers, cancers caused by a patient's exposure to a carcinogen(s), cancers resulting from the insertion of a genetically engineered oncogene or the knockout of a tumor suppressor gene, and cancers caused by infections, such as viral infections. The term "carcinoma" is art-recognized and refers to a malignant tumor of epithelial or endocrine tissue. The term also includes carcinosarcomas, which include malignant tumors composed of carcinomatous and sarcomatous tissue. "Adenocarcinoma" refers to a cancer derived from glandular tissue or in which the tumor cells form recognizable glandular structures. The term "sarcoma" is art-recognized and refers to a malignant tumor of mesenchymal origin. The term "hematopoietic neoplastic disorder" includes diseases involving hyperplastic / neoplastic cells of hematopoietic origin. Hematopoietic neoplastic disorders can arise from the myeloid, lymphoid, or erythroid lineages, or their precursor cells.

[0087] As used herein, the term "antibody" refers to any antigen-binding molecule that comprises 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 to 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 may contain the Fc region of a human antibody. The term antibody also includes derivatives, e.g., bispecific antibodies formed from antibody fragments, single-chain antibodies, and multispecific antibodies.

[0088] As used 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 to an antigen. In some embodiments, the antigen-binding fragment contains 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.

[0089] As used herein, the term "chimeric antibody" refers to an antibody that contains sequences present in at least two different antibodies (e.g., antibodies from two different mammalian species, such as a human and a non-human antibody). A non-limiting example of a chimeric antibody is an antibody that contains variable domain sequences (e.g., all or part of the light and / or heavy chain variable domain sequences) of a non-human (e.g., mouse, rabbit) antibody and the constant domain of a human antibody. Other examples of chimeric antibodies are described herein and known in the art.

[0090] As used herein, the term "humanized antibody" refers to a non-human antibody that contains minimal sequence derived from non-human (e.g., mouse, rabbit) immunoglobulin and contains sequence derived from human immunoglobulin. In a non-limiting example, a humanized antibody is a human antibody (recipient antibody) in which hypervariable (e.g., CDR) region residues of the recipient antibody are replaced by hypervariable (e.g., CDR) region residues from a non-human antibody (e.g., donor antibody), such as a mouse, rat, or rabbit antibody, possessing the desired specificity, affinity, and capacity. In some embodiments, Fv framework residues of the human immunoglobulin are replaced by corresponding non-human (e.g., mouse, rabbit) immunoglobulin residues. In some embodiments, humanized antibodies may contain residues that are not found in the recipient antibody or the donor antibody. These modifications may be made to further refine antibody performance. In some embodiments, a 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 a non-human (e.g., mouse, rabbit) immunoglobulin and all or substantially all of the framework regions are those of a human immunoglobulin. A humanized antibody may also contain at least a portion of an immunoglobulin constant region (Fc), typically at least a portion of an immunoglobulin constant region (Fc) of a human immunoglobulin. Humanized antibodies can be produced using molecular biology methods known in the art. Non-limiting examples of methods for generating humanized antibodies are described herein.

[0091] As used herein, the terms "subject" and "patient" are used interchangeably throughout the specification and refer to an animal, human or non-human, receiving treatment with the methods of the present invention. Veterinary and non-veterinary applications are contemplated by the present invention. A human patient can be an adult or a juvenile (e.g., a human under the age of 18). In addition to humans, patients include, but are not limited to, mice, rats, hamsters, guinea pigs, rabbits, ferrets, cats, dogs, and primates. Examples include, but are not limited to, non-human primates (e.g., monkeys, chimpanzees, gorillas, etc.), rodents (e.g., rats, mice, gerbils, hamsters, ferrets, rabbits), lagomorphs, porcines (e.g., pigs, minipigs), equines, canines, felines, bovines, and other domestic, farm, and zoo animals.

[0092] 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), preferably another molecule, because the interaction is dependent on the presence of a specific structure (i.e., an antigenic determinant or epitope) on the target molecule. In other words, the reagent 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 the CD79b molecule may be referred to as a CD79b-specific antibody or an anti-CD79b antibody.

[0093] 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.

[0094] 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, without limitation, DNA, RNA, DNA / RNA hybrids, and modifications thereof.

[0095] 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 for use in the present invention are described herein; however, other suitable methods and materials known in the art can also be used. The materials, methods, and examples are illustrative only and are 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.

[0096] Other features and advantages of the invention will become apparent from the following detailed description and drawings, and from the claims. [Brief explanation of the drawings]

[0097] [Figure 1] Figure 1 shows the ELISA binding affinity of anti-CD79b antibodies to human CD79b recombinant protein. [Figure 2] ELISA binding affinity of anti-CD79b antibodies to cynomolgus monkey CD79b recombinant protein. [Figure 3] 1 shows a BLI trace of anti-CD79b antibody binding to human CD79b recombinant protein. [Figure 4] 1 shows the relative internalization of anti-CD79b antibody from the cell surface of Ramos cells. [Figure 5] Quantification of anti-CD79b antigen density on the surface of malignant B tumor cells and normal B cells is shown. [Figure 6] 1 shows the binding affinity of anti-CD79b antibodies to BJAB cells. [Figure 7] 1 shows the binding affinity of anti-CD79b antibodies to Ramos cells. [Figure 8] 1 shows the binding affinity of anti-CD79b antibodies to Daudi cells. [Figure 9] 1 shows the binding affinity of anti-CD79b antibodies to SU-DHL-4 cells. [Figure 10]1 shows the binding affinity of anti-CD79b antibodies to Nalm-6 cells. [Figure 11] Binding affinity of anti-CD79b antibodies to donor 2890 is shown. [Figure 12] Binding affinity of anti-CD79b antibodies to donor 2235 is shown. [Figure 13] Binding affinity of anti-CD79b antibodies to donor 889. [Figure 14] Binding affinity of anti-CD79b antibodies to donor 356 is shown. [Figure 15] 1 shows the binding affinity of anti-CD79b antibodies to CLL donor 5716. [Figure 16] 1 shows the binding affinity of anti-CD79b antibodies to CLL donor 0255. [Figures 17A-17B] 1 shows binding of anti-CD79b antibodies to both the long and short isoforms of CD79b. [Figure 18] Figure 1 shows ELISA binding of humanized anti-CD79b antibodies to recombinant human CD79b ECD. [Figure 19] Binding of humanized anti-CD79b antibodies to cell lines expressing endogenous CD79b is shown. [Figure 20] 1 lists the CDR sequences of anti-CD79b antibodies as defined by the Kabat definition. [Figure 21] Lists the CDR sequences of anti-CD79b antibodies as defined by the Chothia definition. [Figure 22] Listed below are selected amino acid sequences considered in this disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0098] The B lymphocyte antigen receptor is a multimeric complex containing the antigen-specific component, surface immunoglobulin (Ig). Surface Ig noncovalently associates with two other proteins, CD79a and CD79b, which are necessary for B cell antigen receptor expression and function. CD79 is a signaling component of the B cell receptor and functions as a covalent heterodimer containing CD79a (i.e., Ig-α or MB1) and CD79b (i.e., Ig-β or B29). CD79b contains an extracellular immunoglobulin (Ig) domain, a transmembrane domain, an intracellular signaling domain, and an immunoreceptor tyrosine-based activation motif (ITAM) domain. CD79b expression has been detected on the surface of nearly all non-Hodgkin's lymphoma (NHL) and in patients with acute lymphoblastic leukemia (ALL) and chronic lymphocytic leukemia (CLL).

[0099] The present disclosure provides examples of antibodies, antigen-binding fragments thereof, that bind to CD79b. CD79b

[0100] CD79 is composed of CD79a and CD79b components, which are expressed almost exclusively on B cells and B cell neoplasms. Expression of CD79a and CD79b precedes immunoglobulin (Ig) heavy chain gene rearrangement and CD20 expression during B cell development and disappears later than CD20 at later stages of B cell differentiation (plasma cells). Therefore, antibodies to CD79a and CD79b are useful for the differential diagnosis of B cell neoplasms from T cell or myeloid neoplasms, or between L- and H-lymphocyte-predominant and classical Hodgkin lymphoma. In addition, anti-CD79a and anti-CD79b antibodies are useful markers for the diagnosis of precursor B-cell acute lymphoblastic leukemia (pre-B-ALL), because many of these tumors are negative for other B cell markers, such as CD20 and CD45RA.

[0101] CD79 is considered an interesting therapeutic target for antibodies because it is physiologically exclusively expressed on mature B cells and the majority of B-cell NHLs, including not only DLBCL (90-100%) but also 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), and mantle cell lymphoma (MCL).

[0102] CD79 associates with cell surface immunoglobulins (sIg) for antigen recognition to form the B cell antigen receptor (BCR) complex, which plays a key role in B cell maturation and activation. CD79 consists of an α (CD79a) and β (CD79b) heterodimer that functions as a signaling component of the BCR. Both CD79 subunits contain a single extracellular Ig domain, a transmembrane domain, and an intracellular signaling domain that initiates BCR signaling after antigen binding, ultimately leading to B cell activation, antigen presentation, cytokine production, and cell proliferation and differentiation.

[0103] Antigen binding of the BCR induces its internalization and translocation 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 particularly interesting because it allows drugs to be delivered directly to the lysosomal compartment of target cells, enhancing cytotoxic activity and allowing the use of more stable linkers that are cleaved in the MHCII compartment.

[0104] Detailed reviews of CD79b and its functions are provided in Chu, Peiguo G., and Daniel A. Arber. "CD79: a review." Applied Immunohistochemistry & Molecular Morphology 9.2 (2001): 97-106 and 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 in its entirety.

[0105] The present disclosure 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. Antibodies and antigen-binding fragments

[0106] The present disclosure provides anti-CD79b antibodies and antigen-binding fragments thereof. Generally, antibodies (also called immunoglobulins) are composed of two classes of polypeptide chains: light chains and heavy chains. A non-limiting example of an antibody of the present disclosure may be an intact four-immunoglobulin chain antibody, comprising two heavy chains and two light chains. The heavy chain of the antibody may be of any isotype, including IgM, IgG, IgE, IgA, or IgD, or any subisotype, including IgG1, IgG2, IgG2a, IgG2b, IgG3, IgG4, IgE1, IgE2, etc. The light chain may be a kappa light chain or a lambda light chain. The antibody may comprise two identical copies of the light chain and two identical copies of the heavy chain. The heavy chains each contain one variable domain (or variable region, VH) and multiple constant domains (or constant regions), which are bound to each other via disulfide bonds within the constant domains to form the "stem" of the antibody. Each light chain contains one variable domain (or variable region, VL) and one constant domain (or constant region), which are bound to one heavy chain via disulfide bonds. The variable region of each light chain is aligned with the variable region of the heavy chain to which it is bound. The variable regions of both the light and heavy chains contain three hypervariable regions sandwiched between more conserved framework regions (FR).

[0107] These hypervariable regions, known as complementarity-determining regions (CDRs), form the loops that comprise the primary antigen-binding surface of an antibody. The four framework regions largely adopt a β-sheet conformation, and the CDRs form loops that connect, and in some cases form part of, the β-sheet structure. The CDRs in each chain are held in close proximity by the framework regions and, together with the CDRs from the other chain, contribute to the formation of the antigen-binding region.

[0108] Methods for identifying CDR regions of antibodies by analyzing their amino acid sequences are well known, and a number of definitions of CDRs are commonly used: the Kabat definition is based on sequence variability, and the Chothia definition is based on the location of structural loop regions. These methods and definitions are described, for example, in Martin, "Protein sequence and structure analysis of antibody variable domains," Antibody engineering, Springer Berlin Heidelberg, 2001, pp. 422-439; Abhinandan, et al., "Analysis and improvements to Kabat and structurally correct numbering of antibody variable domains," Molecular immunology 45.14 (2008): 3832-3839; Wu, TT and Kabat, EA (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., Nature 342(6252):877-83 (Dec. 1989), Ponomarenko and Bourne, BMC Structural Biology 7:64 (2007).

[0109] CDRs are important for recognizing the epitope of an antigen. As used herein, "epitope" is the smallest portion of a target molecule that can be specifically bound by the antigen-binding domain of an antibody. The minimum size of an epitope can be about 3, 4, 5, 6, or 7 amino acids, but these amino acids do not need to be a continuous linear sequence of the primary structure of the antigen, as the epitope can depend on the three-dimensional arrangement of the antigen based on the secondary and tertiary structure of the antigen.

[0110] In some embodiments, antibodies are intact immunoglobulin molecules (e.g., IgG1, IgG2a, IgG2b, IgG3, IgM, IgD, IgE, IgA). The IgG subclasses (IgG1, IgG2, IgG3, and IgG4) are highly conserved and differ in their constant regions, particularly the hinge and upper CH2 domains. The sequences and differences between IgG subclasses are known in the art and are described, for example, 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, and Shakib, Farouk, ed., The human IgG subclasses: molecular analysis of structure, function and regulation. Elsevier, 2016, each of which is incorporated herein by reference in its entirety.

[0111] An antibody may be an immunoglobulin molecule from any species (e.g., human, rodent, murine, camelid, rabbit). Antibodies disclosed herein also include, but are not limited to, polyclonal antibodies, monoclonal antibodies, monospecific antibodies, multispecific antibodies, and chimeric antibodies comprising an immunoglobulin binding domain fused to another polypeptide. The term "antigen-binding domain" or "antigen-binding fragment" refers to a portion of an antibody that retains the specific binding activity of the intact antibody, i.e., any portion of an antibody that is capable of specifically binding to an epitope on the intact antibody's target molecule. It includes, for example, Fab, Fab', F(ab')2, and variants of these fragments. Thus, in some embodiments, an antibody or antigen-binding fragment thereof may be, for example, an scFv, Fv, Fd, diabody, single-chain antibody molecule, multispecific antibody formed from antibody fragments, and any polypeptide comprising a binding domain that is or is homologous to an antibody-binding domain. Non-limiting examples of antigen-binding domains include, for example, the heavy and / or light chain CDRs of an intact antibody, the heavy chain variable region and / or light chain variable region of an intact antibody, a full-length heavy or light chain of an intact antibody, or individual CDRs from a heavy or light chain of an intact antibody.

[0112] In some embodiments, the antigen-binding fragment can 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. Anti-CD79b antibodies and antigen-binding fragments

[0113] The present disclosure provides antibodies and antigen-binding fragments thereof that specifically bind to CD79b (e.g., human CD79b). The antibodies and antigen-binding fragments described herein can bind 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.

[0114] The present disclosure provides, for example, anti-CD79b antibodies 22D10, 23D8, 29C3, 44G2, 48H10, 57B9, chimeric antibodies thereof, and humanized antibodies thereof.

[0115] The CDR sequences of the 22D10 antibody and 22D10-derived antibodies (e.g., humanized antibodies) include the CDRs of the heavy chain variable domains of SEQ ID NOs: 9, 11, and 13, and the CDRs of the light chain variable domains of SEQ ID NOs: 14-16, as defined by the Kabat definition. CDRs may also be defined by the Chothia definition, in which the CDR sequences of the heavy chain variable domains are set forth in SEQ ID NOs: 10, 12, and 13, and the CDR sequences of the light chain variable domains are set forth in SEQ ID NOs: 14-16.

[0116] Similarly, the CDR sequences of the 23D8 antibody and 23D8-derived antibodies, as defined by the Kabat definition, include the CDRs of the heavy chain variable domains of SEQ ID NOs: 19, 21, and 23, and the CDRs of the light chain variable domains of SEQ ID NOs: 24 to 26. Under the Chothia definition, the CDR sequences of the heavy chain variable domains are those shown in SEQ ID NOs: 20, 22, and 23, and the CDRs of the light chain variable domains are those shown in SEQ ID NOs: 24 to 26.

[0117] The CDR sequences of the 29C3 antibody and 29C3-derived antibodies, as defined by the Kabat definition, include the CDRs of the heavy chain variable domains of SEQ ID NOs: 29, 31, and 33, and the CDRs of the light chain variable domains of SEQ ID NOs: 34 to 36. Under the Chothia definition, the CDR sequences of the heavy chain variable domains are those shown in SEQ ID NOs: 30, 32, and 33, and the CDRs of the light chain variable domains are those shown in SEQ ID NOs: 34 to 36.

[0118] The CDR sequences of the 44G2 antibody and 44G2-derived antibodies, as defined by the Kabat definition, include the CDRs of the heavy chain variable domains of SEQ ID NOs: 39, 41, and 43, and the CDRs of the light chain variable domains of SEQ ID NOs: 44 to 46. Under the Chothia definition, the CDR sequences of the heavy chain variable domains are those shown in SEQ ID NOs: 40, 42, and 43, and the CDRs of the light chain variable domains are those shown in SEQ ID NOs: 44 to 46.

[0119] The CDR sequences of the 48H10 antibody and 48H10-derived antibodies, as defined by the Kabat definition, include the CDRs of the heavy chain variable domains of SEQ ID NOs: 49, 51, and 53, and the CDRs of the light chain variable domains of SEQ ID NOs: 54 to 56. Under the Chothia definition, the CDR sequences of the heavy chain variable domains are set forth in SEQ ID NOs: 50, 52, and 53, and the CDRs of the light chain variable domains are set forth in SEQ ID NOs: 54 to 56.

[0120] The CDR sequences of the 57B9 antibody and 57B9-derived antibodies, as defined by the Kabat definition, include the CDRs of the heavy chain variable domains of SEQ ID NOs: 59, 61, and 63, and the CDRs of the light chain variable domains of SEQ ID NOs: 64 to 66. Under the Chothia definition, the CDR sequences of the heavy chain variable domains are set forth in SEQ ID NOs: 60, 62, and 63, and the CDRs of the light chain variable domains are set forth in SEQ ID NOs: 64 to 66.

[0121] The amino acid sequence of the heavy chain variable region of the 22D10 antibody is shown in SEQ ID NO: 7. The amino acid sequence of the light chain variable region of the 22D10 antibody is shown in SEQ ID NO: 8.

[0122] The amino acid sequence of the heavy chain variable region of the 23D8 antibody is shown in SEQ ID NO: 17. The amino acid sequence of the light chain variable region of the 23D8 antibody is shown in SEQ ID NO: 18.

[0123] The amino acid sequence of the heavy chain variable region of the 29C3 antibody is shown in SEQ ID NO: 27. The amino acid sequence of the light chain variable region of the 29C3 antibody is shown in SEQ ID NO: 28.

[0124] The amino acid sequence of the heavy chain variable region of the 44G2 antibody is shown in SEQ ID NO: 37. The amino acid sequence of the light chain variable region of the 44G2 antibody is shown in SEQ ID NO: 38.

[0125] The amino acid sequence of the heavy chain variable region of the 48H10 antibody is shown in SEQ ID NO: 47. The amino acid sequence of the light chain variable region of the 48H10 antibody is shown in SEQ ID NO: 48.

[0126] The amino acid sequence of the heavy chain variable region of the 57B9 antibody is shown in SEQ ID NO: 57. The amino acid sequence of the light chain variable region of the 57B9 antibody is shown in SEQ ID NO: 58.

[0127] In some embodiments, the anti-CD79b antibody is a humanized antibody. In some embodiments, the anti-CD79b antibody is humanized 23D8, 44G2, 48H10, or 57B9.

[0128] The amino acid sequence of the heavy chain variable region of the humanized 23D8 antibody is shown in SEQ ID NO: 69. The amino acid sequence of the light chain variable region of the 23D8 antibody is shown in SEQ ID NO: 70.

[0129] The amino acid sequence of the heavy chain variable region of the humanized 44G2 antibody is shown in SEQ ID NO: 71. The amino acid sequence of the light chain variable region of the 44G2 antibody is shown in SEQ ID NO: 72.

[0130] The amino acid sequence of the heavy chain variable region of the humanized 48H10 antibody is shown in SEQ ID NO: 73. The amino acid sequence of the light chain variable region of the 48H10 antibody is shown in SEQ ID NO: 74.

[0131] The amino acid sequence of the heavy chain variable region of the humanized 57B9 antibody is shown in SEQ ID NO: 75. The amino acid sequence of the light chain variable region of the 57B9 antibody is shown in SEQ ID NO: 76.

[0132] Also provided are amino acid sequences of the heavy and light chain variable regions of the modified antibodies. 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 of SEQ ID NOs: 7, 17, 27, 37, 47, 57, 69, 71, 73, and 75. 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 of SEQ ID NOs: 8, 18, 28, 38, 48, 58, 70, 72, 74, and 76. The heavy chain variable region sequence can be paired with the corresponding light chain variable region sequence, and both bind to CD79b.

[0133] The humanization percentage refers to the percentage of identity of the heavy or light chain variable region sequence compared to human antibody sequences in the International Immunogenetics Information System (IMGT) database. In some 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 top hits are known in the art and are described, for example, 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. A high humanization percentage often offers various advantages, such as greater safety and efficacy in humans, better tolerance in human subjects, and / or a reduced likelihood of side effects. In some embodiments, the variable regions are fully human, e.g., derived from human heavy chain immunoglobulin locus sequences (e.g., recombinants of human IGHV, human IGHD, and human IGHJ genes) and / or human kappa chain immunoglobulin locus sequences (e.g., recombinants of human IGKV and human IGKJ genes).

[0134] Furthermore, in some embodiments, the antibodies or antigen-binding fragments thereof described herein may contain one, two, or three heavy chain variable region CDRs selected from the group consisting of SEQ ID NOs: 9, 11, 13, 19, 21, 23, 29, 31, 33, 39, 41, 43, 49, 51, 53, 59, 61, 63, 10, 12, 13, 20, 22, 23, 30, 32, 33, 40, 42, 43, 50, 52, 53, and 60, 62, 63, and / or one, two, or three light chain variable region CDRs selected from the group consisting of SEQ ID NOs: 14 to 16, 24 to 26, 34 to 36, 44 to 46, 54 to 56, and 64 to 66.

[0135] In some embodiments, the antibody may have a heavy chain variable region (VH) comprising complementarity determining regions (CDRs) 1, 2, and 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, the antibody may have a light chain variable region (VL) comprising CDR1, 2, and 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. Selected VH CDR1, 2, and 3 amino acid sequences and selected VL CDR1, 2, and 3 amino acid sequences are shown in Figure 20 (Kabat CDRs) and Figure 21 (Chotia CDRs).

[0136] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable domain containing one, two, or three of the 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.

[0137] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable domain containing one, two, or three of the 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.

[0138] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable domain containing one, two, or three of the 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; or SEQ ID NO: 33 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0139] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable domain containing one, two, or three of the 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; or SEQ ID NO: 43 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0140] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable domain containing one, two, or three of the 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; or SEQ ID NO: 53 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0141] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable domain containing one, two, or three of the 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; or SEQ ID NO: 63 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0142] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable domain containing one, two, or three of the 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; or SEQ ID NO: 13 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0143] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable domain containing one, two, or three of the 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.

[0144] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable domain containing one, two, or three of the 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.

[0145] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable domain containing one, two, or three of the 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.

[0146] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable domain containing one, two, or three of the 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.

[0147] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a heavy chain variable domain containing one, two, or three of the 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.

[0148] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a light chain variable domain containing one, two, or three of the CDRs of SEQ ID NO: 14 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 15 with zero, one, or two amino acid insertions, deletions, or substitutions; or SEQ ID NO: 16 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0149] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a light chain variable domain containing one, two, or three of the CDRs of SEQ ID NO: 24 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 25 with zero, one, or two amino acid insertions, deletions, or substitutions; or SEQ ID NO: 26 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0150] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a light chain variable domain containing one, two, or three of the CDRs of SEQ ID NO: 34 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 35 with zero, one, or two amino acid insertions, deletions, or substitutions; or SEQ ID NO: 36 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0151] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a light chain variable domain containing one, two, or three of the CDRs of SEQ ID NO: 44 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 45 with zero, one, or two amino acid insertions, deletions, or substitutions; or SEQ ID NO: 46 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0152] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a light chain variable domain containing one, two, or three of the CDRs of SEQ ID NO: 54 with zero, one, or two amino acid insertions, deletions, or substitutions; SEQ ID NO: 55 with zero, one, or two amino acid insertions, deletions, or substitutions; or SEQ ID NO: 56 with zero, one, or two amino acid insertions, deletions, or substitutions.

[0153] In some embodiments, the antibodies or antigen-binding fragments described herein may contain a light chain variable domain containing one, two, or three of the CDRs of 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.

[0154] Insertions, deletions, and substitutions can be made within the CDR sequences or at either or both ends of the CDR sequences. In some embodiments, the CDRs are determined based on the Kabat definition. In some embodiments, the CDRs are determined based on the Chothia definition. In some embodiments, the CDRs are determined based on a combination of the Kabat and Chothia definitions.

[0155] The present disclosure also provides an antibody or antigen-binding fragment thereof that binds to CD79b. The antibody or antigen-binding fragment thereof comprises a heavy chain variable region (VH) comprising or consisting of an amino acid sequence at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% 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%, 95%, 96%, 97%, 98%, or 99% 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.

[0156] 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.

[0157] 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 are described, for example, 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 herein by reference 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 are described, for example, 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 herein by reference in its entirety.

[0158] 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 may be introduced into one or both of the first and second amino acid or nucleic acid sequences for optimal alignment, and non-homologous sequences may be ignored for comparison purposes). 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, the molecules are identical at that position. The percent identity between two sequences is a function of the number of identical positions shared by the sequences, taking into account the number of gaps that need to be introduced for optimal alignment of the two sequences and the length of each gap. For example, sequence comparison and determination of percent identity between two sequences can be accomplished using the Blossum62 scoring matrix, with a gap penalty of 12, a gap extension penalty of 4, and a frameshift gap penalty of 5.

[0159] The present disclosure also provides nucleic acids comprising polynucleotides encoding polypeptides comprising immunoglobulin heavy chains or immunoglobulin light chains. The immunoglobulin heavy chains or immunoglobulin light chains comprise the CDRs shown in Figure 20 or Figure 21, or have the sequences shown in Figure 22. When the polypeptides are paired with a corresponding polypeptide (e.g., a corresponding heavy chain variable region or a corresponding light chain variable region), the paired polypeptides bind to CD79b (e.g., human CD79b).

[0160] Anti-CD79b antibodies and antigen-binding fragments may be antibody variants (derivatives and conjugates) of antibodies or antibody fragments, and multispecific (e.g., bispecific) antibodies or antibody fragments. Additional antibodies provided herein are polyclonal antibodies, monoclonal antibodies, multimeric antibodies, multispecific (e.g., bispecific) antibodies, humanized antibodies, chimeric antibodies (e.g., human-mouse chimeras), single-chain antibodies, intracellularly produced antibodies (i.e., intrabodies), and antigen-binding fragments thereof. The antibodies or antigen-binding fragments thereof 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 antigen-binding fragment thereof is an IgG antibody or antigen-binding fragment thereof.

[0161] Antibody fragments are suitable for use in the provided methods, so long as they retain the desired affinity and specificity of the full-length antibody. Thus, antibody fragments that bind to CD79b retain the ability to bind to CD79b. Fv fragments are antibody fragments that contain a complete antigen recognition and binding site. This region consists of a dimer of one heavy-chain variable domain and one light-chain variable domain in tight association, essentially covalently linked, as in scFvs. It is in this configuration that the three CDRs of each variable domain interact to define an antigen-binding site on the surface of the VH-VL dimer. Collectively, the six CDRs, or a subset thereof, confer antigen-binding specificity to the antibody. However, even a single variable domain (or half of an Fv containing only three CDRs specific for an antigen) can recognize and bind antigen, although usually with lower affinity than the entire binding site.

[0162] Single-chain Fv or (scFv) antibody fragments comprise the VH and VL domains (or regions) of an antibody, wherein these domains are present in a single polypeptide chain. Generally, the scFv polypeptide further comprises a polypeptide linker between the VH and VL domains which enables the scFv to form the desired structure for antigen binding.

[0163] Fab fragments contain the variable and constant domains of the light chain and the variable and first constant domain (CH1) of the heavy chain. F(ab')2 antibody fragments generally comprise a pair of Fab fragments covalently linked by hinge cysteines near their carboxy termini. Other chemical couplings of antibody fragments are known in the art.

[0164] The antibodies and antibody fragments of the present disclosure may be modified in the Fc region to provide desired effector functions or serum half-lives, hi some embodiments, the Fc region may be modified to inhibit or reduce complement-dependent cytotoxicity (CDC) or antibody-dependent cellular cytotoxicity (ADCC).

[0165] In some embodiments, multispecific antibodies are bispecific antibodies. Bispecific antibodies may be generated by engineering the interface between a pair of antibody molecules to maximize the percentage of heterodimers recovered from recombinant cell culture. For example, the interface may comprise at least a part of the CH3 domain of an antibody constant domain. In this method, one or more small amino acid side chains from the interface of a first antibody molecule are replaced with larger side chains (e.g., tyrosine or tryptophan). Compensatory "cavities" of identical or similar size to the large side chain(s) are created at the interface of a second antibody molecule by replacing the large amino acid side chain(s) with smaller ones (e.g., alanine or threonine). This provides a mechanism for increasing the yield of heterodimers over other unwanted end-products, such as homodimers. This method is described, for example, in WO 96 / 27011, incorporated by reference in its entirety.

[0166] 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 solution). Non-limiting examples of stabilizing molecules include polymers (e.g., polyethylene glycol) or proteins (e.g., 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 the human body).

[0167] In some embodiments, the antibodies or antigen-binding fragments described herein can be conjugated to a therapeutic agent. Antibody-drug conjugates comprising the antibodies or antigen-binding fragments thereof can be covalently or non-covalently bound to a 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, tenoposide, vincristine, vinblastine, colchicine, doxorubicin, daunorubicin, dihydroxyanthracin, maytansinoids such as DM-1 and DM-4, ​​dione, mitoxantrone, mithramycin, actinomycin D, 1-dehydrotestosterone, glucocorticoids, procaine, tetracaine, lidocaine, propranolol, puromycin, epirubicin, and cyclophosphamide and its analogs).

[0168] 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., the extracellular region of human CD79b). Antibody Drug Conjugates (ADCs)

[0169] 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 may be covalently or non-covalently bound to the antibody or antigen-binding fragment or antigen-binding protein construct (e.g., bispecific antibody).

[0170] 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, tenoposide, vincristine, vinblastine, colchicine, doxorubicin, daunorubicin, dihydroxyanthracin, maytansinoids such as DM-1 and DM-4, ​​dione, mitoxantrone, mithramycin, actinomycin D, 1-dehydrotestosterone, glucocorticoids, procaine, tetracaine, lidocaine, propranolol, puromycin, epirubicin, and cyclophosphamide and its analogs). Useful classes of cytotoxic, cytostatic, or immunomodulatory agents include, for example, antitubulin agents, DNA minor groove binders, DNA replication inhibitors, and alkylating agents.

[0171] In some embodiments, the therapeutic agent may include, but is not limited to, a cytotoxic agent such as a chemotherapeutic agent, an immunotherapeutic agent, an antiviral agent, or an antibacterial agent. In some embodiments, the conjugated therapeutic agent may be selected from, but is not limited to, MMAE (monomethylauristatin E), MMAD (monomethylauristatin D), or MMAF (monomethylauristatin F).

[0172] In some embodiments, the therapeutic agent is an auristatin or a derivative thereof, such as auristatin E (also known in the art as a derivative of dolastatin-10). The auristatin can be, for example, an ester formed between auristatin E and a keto acid. For example, auristatin E can be reacted with paraacetylbenzoic acid or benzoylvaleric acid to produce AEB and AEVB, respectively. Other exemplary auristatins include AFP, MMAF, and MMAE. The synthesis and structures 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. Patents 7,498,298, 6,884,869, 6,323,315, 6,239,104, 6,034,065, 5,777,787, each of which is incorporated herein by reference in its entirety for all purposes. Nos. 80,588, 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, and 4,486,414.

[0173] Auristatins inhibit microtubule dynamics and nuclear and cell division and have been shown to have anti-cancer activity. Auristatins bind to tubulin and can exert cytotoxic or cytostatic effects on cancer cells. Many different assays are known in the art that can be used to determine whether an auristatin or the resulting antibody-drug conjugate exerts a cytotoxic or cytostatic effect on the desired cells.

[0174] In some embodiments, the therapeutic agent is a chemotherapeutic agent. Examples of chemotherapeutic agents include alkylating agents such as thiotepa and cyclosphosphamide (CYTOXAN™), alkyl sulfonates such as busulfan, improsulfan, and piposulfan, aziridines such as benzodopa, carboquone, meturedopa, and uredopa, ethylenimines and methylameramines such as altretamine, triethylenemelamine, triethylenephosphoramide, triethylenethiophosphoramide, and trimethylolmelamine, and nitrogen methylameramines. mustards such as chlorambucil, chlornaphazine, colofosfamide, estramustine, ifosfamide, mechlorethamine, mechlorethamine oxide hydrochloride, melphalan, nobembine, phenesterine, prednimustine, trofosfamide, uracil mustard, etc.; nitrosureas such as carmustine, chlorozotocin, fotemustine, lomustine, nimustine, ranimustine, etc.; antibiotics such as aclacinomycin, actinomycin, australamycin, azaserine, bleomycin, cambromycin, Cutinomycin, calicheamicin, carabicin, caminomycin, carzinophilin, chromomycin, dactinomycin, daunorubicin, detorubicin, 6-diazo-5-oxo-L-norleucine, doxorubicin, epirubicin, esorubicin, idarubicin, marcellomycin, mitomycin, mycophenolic acid, nogalamycin, olivomycin, peplomycin, potfilomycin, puromycin, chelamycin, rodorubicin, streptonigrin, streptozocin, tubercidin, ubenimex, zinos tatins, zorubicin, etc., antimetabolites such as methotrexate and 5-fluorouracil (5-FU), etc., folic acid analogues such as denopterin, methotrexate, pteropterin, trimetrexate, etc., purine analogues such as fludarabine, 6-mercaptopurine, thiamiprine, thioguanine, etc., pyrimidine analogues such as ancitabine, azacitidine, 6-azauridine, carmofur, cytarabine, dideoxyuridine, doxifluridine, enocitabine, floxuridine, 5-FU, etc., androgens such as calsterone,Dromostanolone propionate, epitiostanol, mepitiostane, testolactone, etc., antiadrenal drugs such as aminoglutethimide, mitotane, trilostane, etc., folic acid supplements such as furoic acid, aceglatone, aldophosphamide glycoside, aminolevulinic acid, amsacrine, bestravcil, bisantrene, edatraxate, defofamine, demecolcine, diaziquone, elfornithine, elliptinium acetate, etoglucide, gallium nitrate, hydroxyurea, lentinan, lonidamine, mitoguazone, mitoxantrone, mopidamol , nitracrine, pentostatin, fenameth, pirarubicin, podophyllic acid, 2-ethylhydrazide, procarbazine, PSK7, razoxane, sizofiran, spirogermanium, tenuazonic acid, triazicon, 2',2',2'-trichlorotriethylamine, urethane, vindesine, dacarbazine, mannomustine, mitobronitol, mitolactol, pipobroman, gacytosine, arabinoside ("Ara-C"), cyclophosphamide, taxanes, such as paclitaxel (TAXOL®, Bristol-Myers Squibb), Squibb Oncology, Princeton, NJ) and doxetaxel (TAXOTERE®, Rhone-Poulenc Rorer, Antony, France), chlorambucil, gemcitabine, 6-thioguanine, platinum analogs such as cisplatin and carboplatin, vinblastine, platinum, etoposide (VP-16), ifosfamide, mitomycin C, mitoxantrone, vincristine, vinorelbine, navelbine, novantrone, teniposide, daunomycin, aminopterin, xeloda, ibandronate, CPT-11, the topoisomerase inhibitor RFS2000, difluoromethylornithine (DMFO), retinoic acid, esperamicin, capecitabine, and pharmaceutically acceptable salts, acids, or derivatives of any of the above. This definition includes, for example, tamoxifen, raloxifene, aromatase-inhibiting 4(5)-imidazoles, 4-hydroxytamoxifen, trioxifen, keoxifen, LY117018, onapristone,Also included are antihormonal agents that act to regulate or inhibit hormone action on tumors, such as antiestrogens, including toremifene (Fareston), and antiandrogens, 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 is provided, for example, in US20180193477A1, which is incorporated by reference in its entirety.

[0175] In some embodiments, the antigen-binding construct is coupled to the drug via a cleavable linker, such as an SPBD linker or a maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (VC) linker. In some embodiments, the antigen-binding construct is coupled to the drug via a non-cleavable linker, such as an MCC linker formed using SMCC or sulfo-SMCC. Selection of an appropriate linker for a given ADC can be readily achieved by one of skill in the art, taking into account relevant factors such as the site of attachment to the antigen-binding construct, the structural constraints of the drug, and the hydrophobicity of the drug (see, e.g., a review in Nolting, Chapter 5, Antibody-Drug Conjugates: Methods in Molecular Biology, 2013, Ducry (Ed.), Springer). Many specific linker-toxin combinations have been described and, in certain embodiments, can be used with the antigen-binding constructs described herein to prepare ADCs. Examples include cleavable peptide-based linkers with auristatins such as MMAE and MMAF, camptothecins such as SN-38, duocarmycins, and PBD dimers, non-cleavable MC-based linkers with the auristatins MMAF and MMAE, acid-labile hydrazone-based linkers with calicheamicin and doxorubicin, disulfide-based linkers with maytansinoids such as DM1 and DM4, and bis-maleimide-trioxyethylene glycol (BMPEO)-based linkers with the maytansinoid DM1. Some of these therapeutic agents and linkers are described, for example, 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 No. US2015 / 0374847; and US20180193477A1, which are incorporated herein by reference in their entireties.

[0176] Depending on the desired drug and the selected linker, those skilled in the art can select a suitable method for coupling them together. For example, several conventional coupling methods, such as amine coupling methods, can be used to form a drug-linker conjugate that still contains a reactive group for covalent conjugation to an antibody. In some embodiments, a drug-maleimide conjugate (i.e., a maleimide-linked drug) can be used as a payload with a reactive group in the present disclosure. The most common reactive group that can be attached to a thiol group in ADC preparation is maleimide. In addition, organic bromides and iodides are also commonly used.

[0177] ADCs can be prepared by one of skill in the art using organic chemistry reactions, conditions, and reagents via one of several routes (see, for example, Bioconjugate Techniques (G.T. Hermanson, 2013, Academic Press)). For example, conjugation can be achieved by (1) reacting a nucleophilic or electrophilic group on an antibody with a bivalent linker reagent to form an antibody-linker intermediate Ab-L via a covalent bond, which is then reacted with an activated drug moiety D, or (2) reacting a nucleophilic or electrophilic group on a drug moiety with a linker reagent to form a drug-linker intermediate DL via a covalent bond, which is then reacted with a nucleophilic or electrophilic group on an antibody. Conjugation methods (1) and (2) can be used to prepare the ADCs described herein using a variety of antibodies, drug moieties, and linkers. The various prepared linkers, linker components, and toxins are commercially available or can be prepared by standard synthetic organic chemistry techniques. These methods are described, for example, 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 (G.T. Hermanson, 2013, Academic Press), US20210379193A1, and US20180193477A1, which are incorporated by reference in their entireties. In addition, numerous preformed drug-linkers suitable for reaction with a selected antigen-binding construct are commercially available; for example, linker-toxins including DM1, DM4, MMAE, MMAF, or duocarmycin SA are available from Creative BioLabs (Shirley, NY).

[0178] Some specific examples of methods for preparing ADCs are known in the art and are described in U.S. Patent No. 8,624,003 (the Pott method), U.S. Patent No. 8,163,888 (one-step method), and U.S. Patent No. 5,208,020 (the two-step method), which are incorporated herein by reference in their entireties, and in US 20180193477 A1. Other methods are known in the art and include those described in Antibody-Drug Conjugates: Methods in Molecular Biology, 2013, Ducry (Ed.), Springer.

[0179] Drug loading is expressed as the number of drug moieties per antibody molecule in an ADC. For some antibody-drug conjugates, drug loading may be limited by the number of attachment sites on the antibody. For example, when the attachment is a cysteine ​​thiol, as in certain exemplary embodiments described herein, drug loading may be 0 to 8 drug moieties per antibody. In certain embodiments, higher drug loading, e.g., p≧5, may cause 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 is 1 to about 8, about 2 to about 6, or about 3 to about 5. In practice, it has been shown that for certain antibody-drug conjugates, the optimal ratio of drug moieties per antibody may be around 4. In some embodiments, the drug-antibody ratio (DAR) is about or at least 1, 2, 3, 4, 5, 6, 7, or 8. In some embodiments, the average DAR in the 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. Antibody and ADC properties

[0180] The antibodies or antigen-binding fragments thereof, or ADCs derived therefrom described herein can be agonists or antagonists. In some embodiments, by binding to CD79b, the antibodies can inhibit CD79b-mediated BCR signaling.

[0181] In some implementations, the antibody (or antigen-binding fragment thereof) or ADC derived therefrom is -1 Less than 0.01s -1 Less than 0.001s -1 Less than 0.0001s -1 Less than 0.00001s -1 Less than 0.000001s -1 Less than or equal to 0.0000001s -1 Specifically binds to CD79b (e.g., human CD79b, monkey CD79b (e.g., rhesus monkey, cynomolgus monkey), canine CD79b, mouse CD79b) with a k of less than 0.01 s. In some embodiments, the k is less than 0.01 s. -1 Super, 0.001s -1 Super, 0.0001s -1 Super, 0.00001s -1 Super, 0.000001s -1 Super, 0.0000001s -1 Greater than or equal to 0.00000001s -1 It's super.

[0182] In some embodiments, the kinetic association rate (k) is 1×10 2 / Ms super, 1×10 3 / Ms super, 1×10 4 / Ms super, 1×10 5 / Ms or 1 × 10 6 In some embodiments, the kinetic association rate (k) is greater than 1×10 5 / Ms less than 1 × 10 6 / Ms or less than 1 x 10 7 / Ms is less than.

[0183] Affinity can be estimated from the quotient of the kinetic rate constants (K = k / k). In some embodiments, K is 1 x 10 -6 Less than M, 1 x 10 -7 Less than M, 1 x 10 -8 Less than M, 1 x 10 -9 Less than M, 1 x 10 -10 Less than M, 1 x 10 -11 Less than M, 1 x 10 -12 Less than M, 1 x 10 -13Less than M or 1 x 10 -14 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 less than 1 x 10 -7 Super M, 1×10 -8 Super M, 1×10 -9 Super M, 1×10 -10 Super M, 1×10 -11 Super M, 1×10 -12 Super M, 1×10 -13 Super M, 1×10 -14 It's over M.

[0184] Common 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, an antibody or antigen-binding fragment thereof described herein, or an ADC derived therefrom, binds to human CD79b, monkey CD79b, canine CD79b, and / or mouse CD79b. In some embodiments, the antibody does not bind to human CD79b, monkey CD79b, canine CD79b, and / or mouse CD79b.

[0185] Additionally, an alternative splice isoform has been described for CD79b 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 229 amino acid wild-type (also referred to as the "long isoform") (SEQ ID NO: 68) by the deletion of exon 3, which essentially encodes most 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 antibody binds to a CD79b isoform (e.g., SEQ ID NO: 67). In some embodiments, the anti-CD79b antibody does not bind to a CD79b isoform (e.g., SEQ ID NO: 67). In some embodiments, the anti-CD79b antibody binds to wild-type CD79b (e.g., SEQ ID NO: 68). In some embodiments, the antibodies described herein bind to the extracellular domain of CD79b.

[0186] 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).

[0187] In some embodiments, antibodies or antigen-binding fragments thereof described herein, or ADCs derived therefrom, are added to Ramos cells to examine internalization rates. In some embodiments, at various time points (e.g., 1 hour, 3 hours, or 6 hours), 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, antibodies or antigen-binding fragments thereof described herein, or ADCs derived therefrom, have a slower internalization rate than polatuzumab.

[0188] In some embodiments, thermal stability is determined. An antibody or antigen-binding fragment thereof described herein, or ADC derived therefrom, can have a Tm of 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.

[0189] Because IgG can be described as a multidomain protein, the melting curve may exhibit two transitions, at a first denaturation temperature, Tm1, and a second denaturation temperature, Tm2. The presence of these two peaks often indicates the 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 of 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.

[0190] 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.

[0191] In some embodiments, the antibodies or antigen-binding fragments thereof or ADCs derived therefrom described herein can bind to human or monkey CD79b as measured by ELISA. In some embodiments, the antibodies or antigen-binding fragments thereof described herein or ADCs derived therefrom can bind to 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.

[0192] In some embodiments, the antibodies or antigen-binding fragments thereof or ADCs derived therefrom described herein are capable of binding to the same epitope on CD79b. In some embodiments, the antibodies or antigen-binding fragments thereof or ADCs derived therefrom described herein are capable of binding to different epitopes on CD79b.

[0193] In some embodiments, an antibody or antigen-binding fragment thereof described herein, or an ADC derived therefrom, can bind to malignant B-cell lines (e.g., BJAB, Ramos, Daudi, SU-DHL-4, and Nalm-6) at both high and low CD79b antigen densities as measured 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.

[0194] In some embodiments, the antibodies or antigen-binding fragments thereof, or ADCs derived therefrom described herein can bind to human B cells with a cell surface binding affinity greater than that of polatuzumab, ie, 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.

[0195] In some embodiments, the antibodies or antigen-binding fragments thereof or ADCs derived therefrom described herein can bind to cell surface CD79b on B lymphocytes from patients with chronic lymphocytic leukemia (CLL), and in some embodiments, the binding is more potent than polatuzumab.

[0196] In some embodiments, the ADCs described herein have an average drug-antibody ratio (DAR) as measured by HPLC of greater than 3, greater than 3.2, greater than 3.4, greater than 3.6, greater than 3.8, greater than 4, greater than 4.2, greater than 4.4, or greater than 4.6. In some embodiments, the ADCs described herein have an average DAR as measured by HPLC of less than 3, less than 3.2, less than 3.4, less than 3.6, less than 3.8, less than 4, less than 4.2, less than 4.4, or less than 4.6. In some embodiments, the DAR is about 4.

[0197] In some embodiments, the antibodies or antigen-binding fragments thereof, or ADCs derived therefrom described herein have a tumor growth inhibition percentage (TGI%) of more 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 antibodies or antigen-binding fragments thereof, or ADCs derived therefrom described herein have a tumor growth inhibition percentage of less than 60%, 70%, 80%, 90%, 100%, 110%, 120%, 130%, 140%, 150%, 160%, 170%, 180%, 190%, or 200%. TGI% can be measured, for example, at 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 initiation of treatment, or at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 months after initiation of treatment. As used herein, tumor growth inhibition percentage (TGI%) is calculated according to the following formula:

number

[0198] Ti is the mean tumor volume of the treatment group on day i. T0 is the mean tumor volume of the treatment group on day 0. Vi is the mean tumor volume of the control group on day i. V0 is the mean tumor volume of the control group on day 0.

[0199] In some embodiments, the antibodies or antigen-binding fragments thereof or ADCs derived therefrom described herein are capable of binding to tumor cells expressing CD79b. In some embodiments, the antibodies or antigen-binding fragments thereof described herein or ADCs derived therefrom are capable of inducing complement-dependent cytotoxicity (CDC) and / or antibody-dependent cellular cytotoxicity (ADCC) and killing tumor cells.

[0200] In some embodiments, an antibody or antigen-binding fragment thereof, or ADC derived therefrom, described herein, comprises 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.

[0201] 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 SI, LALA, N297A, YTE, and / or FLAA mutations. In some embodiments, the antibody is a humanized IgG4 antibody, optionally with SI, LALA, N297A, YTE, and / or FLAA mutations.

[0202] 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 SI 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). Method for producing anti-CD79b antibodies

[0203] Isolated fragments of human CD79b (e.g., the CD79b extracellular domain) can be used as immunogens to generate antibodies using standard techniques for polyclonal and monoclonal antibody preparation. Polyclonal antibodies can be raised 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 being immunized. Animals can be injected multiple times (e.g., two, three, or four times) with the antigenic peptide or protein.

[0204] The full-length polypeptide or protein (or its extracellular region) may be used as an immunogen, or an antigenic peptide fragment thereof may 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 encompasses an epitope of the protein such that antibodies raised against the peptide form specific immune complexes with the protein. As noted above, the full-length sequence of human CD79b is known in the art. In some embodiments, an Fc-tagged or His-tagged human CD79b protein is used as an immunogen. In some embodiments, the extracellular domain (ECD) of human CD79b is used as an immunogen.

[0205] An immunogen is typically used to prepare antibodies by immunizing a suitable subject (e.g., a human or a transgenic animal expressing at least one human immunoglobulin locus). An appropriate immunogenic preparation can contain, for example, a recombinantly expressed or chemically synthesized polypeptide (e.g., a fragment of human CD79b). The preparation may further include an adjuvant, such as complete or incomplete Freund's adjuvant, or a similar immunostimulant.

[0206] Polyclonal antibodies can be prepared, as described above, by immunizing a suitable subject with a CD79b polypeptide, or an antigenic peptide thereof (e.g., a portion of CD79b) as an immunogen. Antibody titers in immunized subjects can be monitored over time by standard techniques, such as enzyme-linked immunosorbent assay (ELISA) using immobilized CD79b polypeptide or peptide. If desired, the antibody molecules can be isolated from the mammal (e.g., from the blood) and further purified by well-known techniques, such as protein A or protein G chromatography, to obtain the IgG fraction. At an appropriate time after immunization, e.g., when the specific antibody titer is highest, antibody-producing cells can be harvested from the subject and used to prepare monoclonal antibodies by standard techniques, such as the hybridoma technique first 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 the trioma technique. Technology for producing hybridomas is well known (see generally, Current Protocols in Immunology, 1994, Coligan et al. (Eds.), John Wiley & Sons, Inc., New York, NY). Hybridoma cells producing a monoclonal antibody are detected by screening the hybridoma culture supernatants for antibodies that bind the polypeptide or epitope of interest, eg, using a standard ELISA assay.

[0207] Variants of the antibodies or antigen-binding fragments described herein can be prepared by introducing appropriate nucleotide changes into DNA encoding the human, humanized, or chimeric antibodies or antigen-binding fragments thereof described herein, or by peptide synthesis. Such variants include, for example, deletions, insertions, or substitutions of residues within the amino acid sequence constituting the antigen-binding site or domain of the antibody. Within a population of such variants, some antibodies or antigen-binding fragments have increased affinity for a target protein, e.g., CD79b. Any combination of deletions, insertions, and / or combinations can be used to obtain antibodies or antigen-binding fragments thereof with increased binding affinity for the target. Amino acid changes introduced into the antibody or antigen-binding fragment can also alter the antibody or antigen-binding fragment or introduce new post-translational modifications, such as changing the number (increase or decrease) of glycosylation sites, changing the type of glycosylation site (e.g., by altering the amino acid sequence so that different sugars are attached by enzymes present in cells), or introducing new glycosylation sites.

[0208] The antibodies disclosed herein may be derived from any species of animal, including mammals. Non-limiting examples of natural antibodies include antibodies derived from humans, primates (e.g., monkeys and apes), rabbits, cows, pigs, horses, sheep, camelids (e.g., camels and llamas), chickens, goats, and rodents (e.g., rats, mice, hamsters, and rabbits), among others, including antibodies derived from transgenic animals that have been genetically engineered to produce human antibodies.

[0209] Human and humanized antibodies include antibodies that have variable and constant regions derived from human germline immunoglobulin sequences (or have the same amino acid sequences as derived from human germline immunoglobulin sequences). Human antibodies may include amino acid residues, for example in the CDRs, that are not encoded by human germline immunoglobulin sequences (e.g., mutations introduced by random or site-specific mutagenesis in vitro or by somatic mutation in vivo).

[0210] Humanized antibodies typically have a human framework (FR) into which nonhuman CDRs have been grafted. Thus, a humanized antibody has one or more amino acid sequences introduced from a nonhuman source. These nonhuman amino acid residues are often referred to as "import" residues and are typically obtained from an "import" variable domain. Humanization can be essentially performed, for example, by substituting rodent CDRs or CDR sequences for the corresponding sequences of a human antibody. These methods are described, for example, in Jones et al., Nature, 321:522-525 (1986); Riechmann et al., Nature, 332:323-327 (1988); and Verhoeyen et al., Science, 239:1534-1536 (1988), each of which is incorporated herein by reference in its entirety. Thus, a "humanized" antibody is a chimeric antibody in which substantially less than an intact human V domain has been substituted with the corresponding sequence from a nonhuman species. In practice, humanized antibodies are typically non-human antibodies in which some CDR residues and some FR residues are substituted by residues from analogous sites in human antibodies.

[0211] The selection of human VH and VL domains used to generate a humanized antibody is crucial to reducing immunogenicity. The sequence of the V domain of a non-human antibody is screened against the entire library of known human V domain sequences according to the so-called "best-fit" method. The human sequence that is closest to the sequence of the non-human animal is then 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)).

[0212] It is also important that antibodies be humanized with retention of high specificity and affinity for the antigen and other favorable biological properties. To achieve this goal, humanized antibodies may be prepared by a process of analyzing 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 that illustrate and display predicted three-dimensional conformational structures of selected candidate immunoglobulin sequences. Inspection of these displays permits analysis of the possible role of the residues in the functioning of the candidate immunoglobulin sequence, i.e., analysis of residues that influence the ability of the candidate immunoglobulin to bind to its antigen. In this way, FR residues can be selected and combined from the recipient and import sequences so that desired antibody characteristics, such as increased affinity for the target antigen(s), are achieved.

[0213] Typically, an amino acid sequence variant of a human, humanized, or chimeric anti-CD79b antibody contains an amino acid sequence that has at least 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% percent identity with a sequence present in the light or heavy chain of the original antibody.

[0214] Identity or homology to the original sequence is typically the percentage of amino acid residues present in the candidate sequence that are identical to sequences present in a 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; any conservative substitutions are not considered part of the sequence identity.

[0215] Additional modifications may be made to the anti-CD79b antibody or antigen-binding fragment. For example, cysteine ​​residue(s) may be introduced in the Fc region, thereby allowing interchain disulfide bond formation in this region. The homodimeric antibody thus generated may have increased half-life in vitro and / or in vivo. Homodimeric antibodies with increased half-lives in vitro and / or in vivo may also be prepared using heterobifunctional cross-linkers, e.g., as described by Wolff et al. (Cancer Res. 53:2560-2565, 1993). Alternatively, antibodies with dual Fc regions may be engineered (see, e.g., Stevenson et al., Anti-Cancer Drug Design 3:219-230, 1989).

[0216] In some embodiments, an anti-CD79b antibody or antigen-binding fragment thereof may be covalently modified. These covalent modifications can be made by chemical or enzymatic synthesis, or by enzymatic or chemical cleavage. Other types of covalent modifications of antibodies or antibody fragments are introduced into the molecule by reacting targeted amino acid residues of the antibody or fragment with organic derivatizing agents capable of reacting with selected side chains or the N- or C-terminal residues.

[0217] In some embodiments, antibody variants are provided that have carbohydrate structures lacking fucose attached (directly or indirectly) to the Fc region. For example, the amount of fucose in such antibodies can be 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 in the glycan at Asn297 relative to the sum of all glycostructures (e.g., complex, hybrid, and high-mannose structures) attached to Asn297 as measured by MALDI-TOF mass spectrometry, e.g., as described in WO 2008 / 077546. Asn297 refers to an asparagine residue located at approximately position 297 in the Fc region (position 314 in the EU numbering system or Kabat numbering system for Fc region residues). However, due to minor sequence variations within antibodies, Asn297 can also be located approximately ±3 amino acids upstream or downstream of position 297, i.e., between positions 294 and 300. Such fucosylation variants may have improved ADCC function. In some embodiments, the Fc region of the antibody may be further engineered to replace asparagine at position 297 with alanine (N297A) to reduce glycan heterogeneity.

[0218] In some embodiments, the Fc region of the antibody is further engineered to replace the serine at position 228 (EU numbering) of IgG4 with proline (S228P) to promote production efficiency by avoiding Fab arm exchange. 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 by reference in its entirety. Recombinant vector

[0219] The present disclosure also provides recombinant vectors (e.g., expression vectors) comprising the isolated polynucleotides disclosed herein (e.g., polynucleotides encoding the polypeptides disclosed herein), host cells into which the recombinant vectors have been introduced (i.e., whereby the host cell contains the polynucleotides and / or vectors comprising the polynucleotides), and the production of recombinant antibody polypeptides or fragments thereof by recombinant techniques.

[0220] 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 is introduced. Thus, in an expression vector, a polynucleotide of interest is positioned to be expressed within the vector by operably linking it to regulatory elements, such as a promoter, enhancer, and / or polyA tail, in the vector or host cell genome at, near, or flanking the integration site of the polynucleotide of interest, thereby allowing the polynucleotide of interest to be translated within the host cell into which the expression vector is introduced.

[0221] Vectors can be introduced into host cells by methods known in the art, such as electroporation, chemical transfection (e.g., DEAE-dextran), transformation, transfection, infection, and / or transduction (e.g., into recombinant viruses). Thus, non-limiting examples of vectors include viral vectors (which can be used to produce recombinant viruses), naked DNA or RNA, plasmids, cosmids, phage vectors, and DNA or RNA expression vectors ligated with cationic condensing agents.

[0222] In some implementations, a polynucleotide disclosed herein (e.g., a polynucleotide encoding a polypeptide disclosed herein) is introduced using a viral expression system (e.g., vaccinia or other poxvirus, retrovirus, or adenovirus), and may involve the use of a non-pathogenic (defective), replication-competent virus, or a replication-defective virus. In the latter case, viral propagation generally occurs only in the presence of complementing viral packaging cells. Suitable strains are described, for example, in Fisher-Hoch et al., 1989, Proc. Natl. Acad. Sci. USA 86:317-321, Flexner et al., 1989, Ann. NY 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 skilled in the art. The DNA can be "naked," as described, for example, in Ulmer et al., 1993, Science, 259:1745-1749 and Cohen, 1993, Science, 259:1691-1692. DNA can be coated onto biodegradable beads that are efficiently delivered into cells, increasing the uptake of naked DNA.

[0223] For expression, a DNA insert containing a polynucleotide encoding an antibody or polypeptide disclosed herein may be operably linked to a suitable promoter (e.g., a heterologous promoter), such as the phage lambda PL promoter, the E. coli lac, trp, and tac promoters, the SV40 early and late promoters, and promoters of retroviral long terminal repeats. Other suitable promoters are known to those of skill in the art. The expression construct may further contain sites for transcription start / stop and, in the transcribed region, a ribosome binding site for translation. The coding region of the mature transcript expressed by the construct may include a translation initiation site at the start position and a termination codon (UAA, UGA, or UAG) appropriately positioned at the end of the polypeptide to be translated.

[0224] As noted above, expression vectors may contain at least one selectable marker. Such markers include dihydrofolate reductase or neomycin resistance genes for eukaryotic cell culture, and tetracycline or ampicillin resistance genes for culturing in E. coli and other bacteria. Representative examples of suitable hosts include, but are not limited to, bacterial cells such as E. coli, Streptomyces, and Salmonella cells; fungal cells such as yeast cells; insect cells such as Drosophila S2 and Spodoptera Sf9 cells; animal cells such as CHO, COS, Bowes malignant melanoma, and HK293 cells; and plant cells. Appropriate culture media and conditions for the host cells described herein are known in the art.

[0225] Non-limiting vectors for use in bacteria include pQE70, pQE60, and pQE-9 available from Qiagen, pBS vectors, Phagescript vectors, Bluescript vectors, 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, and pSVK3, pBPV, pMSG, and pSVL available from Pharmacia. Other suitable vectors will be readily apparent to those of skill in the art.

[0226] Non-limiting examples of bacterial promoters that can be used 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 SV40 early and late promoters, promoters of retroviral LTRs (e.g., the Rous sarcoma virus (RSV) promoter), and metallothionein promoters (e.g., the mouse metallothionein-I promoter).

[0227] In brewer's yeast, numerous vectors containing constitutive or inducible promoters, such as alpha factor, alcohol oxidase, and PGH, can be used. For reviews, see Ausubel et al. (1989) Current Protocols in Molecular Biology, John Wiley & Sons, New York, NY, and Grant et al., Methods Enzymol., 153: 516-544 (1997).

[0228] Introduction of the construct into the host cell can be achieved by calcium phosphate transfection, DEAE-dextran mediated transfection, cationic lipid mediated transfection, electroporation, transduction, infection, or other methods, which are described in many standard laboratory manuals, such as, for example, Davis et al., Basic Methods In Molecular Biology (1986), which is incorporated herein by reference in its entirety.

[0229] Insertion of an enhancer sequence into a vector can increase transcription of DNA encoding an antibody of the present disclosure in higher eukaryotes. Enhancers are cis-segment elements of DNA, typically about 10 to 300 bp, that function to increase the transcriptional activity of a promoter in a given host cell type. Examples of enhancers include the SV40 enhancer located after the replication origin at base pairs 100 to 270, the cytomegalovirus early promoter enhancer, the polyoma enhancer located after the replication origin, and adenovirus enhancers.

[0230] For secretion of the translated protein into the lumen of the endoplasmic reticulum, into the periplasmic space or into the extracellular environment, suitable secretion signals may be incorporated into the expressed polypeptide. The signals may be endogenous to the polypeptide or they may be heterologous signals.

[0231] Polypeptides (e.g., antibodies) can be expressed in modified forms, such as fusion proteins (e.g., GST-fusions) or histidine-tagged forms, and may contain not only secretion signals but also additional heterologous functional regions. For example, additional amino acids, particularly a region of charged amino acids, can be added to the N-terminus of a polypeptide to improve stability and durability in host cells during purification or subsequent handling and storage. Peptide moieties can also be added to polypeptides to facilitate purification. Such regions may be removed before final preparation of the polypeptide. Adding peptide moieties to polypeptides to induce secretion or excretion, improve stability, facilitate purification, etc. is a routine technique well known in the art. Treatment method

[0232] The antibodies or antigen-binding fragments thereof of the present disclosure can be used for a variety of therapeutic purposes.

[0233] In one aspect, the present disclosure provides methods for treating cancer in a subject, slowing the rate of growth of a tumor in a subject over time, reducing the risk of developing metastasis, or reducing the risk of a subject developing additional metastases. In some embodiments, treatment can halt, regress, slow, or inhibit the progression of the cancer. In some embodiments, treatment can result in a reduction in the number, severity, and / or duration of one or more symptoms of cancer in a subject.

[0234] In one aspect, the disclosure features a method including administering a therapeutically effective amount of an antibody or antigen-binding fragment thereof disclosed herein to a subject in need thereof (e.g., a subject having, or identified or diagnosed as having, cancer), such as breast cancer (e.g., triple-negative breast cancer), carcinoid cancer, 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. In some embodiments, the cancer is unresectable 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, particularly 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.

[0235] In one aspect, the disclosure provides 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 an antibody or antigen-binding fragment thereof, a CAR, or an antibody drug conjugate described herein.

[0236] 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 arteritis, cold agglutinin disease, warm autoimmune hemolytic anemia, and antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, e.g., granulomatosis with polyangiitis (GPA) (Wegener's granulomatosis) or microscopic polyangiitis (MPA).

[0237] In some embodiments, the autoimmune disease is multiple sclerosis, systemic lupus erythematosus, or rheumatoid arthritis.

[0238] In some embodiments, the compositions and methods disclosed herein can be used to treat patients at risk for cancer. Patients with cancer can be identified by a variety of methods known in the art.

[0239] In one aspect, the present disclosure provides methods for treating, preventing, or reducing the risk of developing disorders associated with an aberrant or unwanted immune response, e.g., autoimmune disorders, including 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, Behçet's disease, pernicious anemia, bullous pemphigoid, polyarteritis nodosa, cardiomyopathy, polychondritis, celiac sprue dermatitis, polyglandular syndrome, chronic fatigue syndrome (CFIDS), polymyalgia rheumatica, chronic inflammatory demyelination, polymyositis and dermatomyositis, chronic inflammatory polyneuropathy, primary agammaglobulinemia, Churg-Strauss syndrome, and rheumatoid arthritis. These conditions include, but are not limited to, advanced biliary cirrhosis, cicatricial pemphigoid, psoriasis, CREST syndrome, Raynaud's phenomenon, cold agglutinin disease, Reiter's syndrome, Crohn's disease, rheumatic fever, discoid lupus, rheumatoid arthritis, cryoglobulinemia, sarcoidosis, fibromyalgia, scleroderma, Graves' disease, Sjogren's syndrome, Guillain-Barre syndrome, stiff-person syndrome, Hashimoto's thyroiditis, Takayasu's arteritis, idiopathic pulmonary fibrosis, temporal arteritis / giant cell arteritis, idiopathic thrombocytopenic purpura (ITP), ulcerative colitis, IgA nephropathy, uveitis, diabetes mellitus (e.g., type 1), vasculitis, lichen planus, and vitiligo. An anti-CD79b antibody or antigen-binding fragment thereof may be administered to a subject to treat, prevent, or reduce the risk of developing a disorder associated with an abnormal or unwanted immune response in cell, tissue, or organ transplantation, such as kidney, liver, and heart transplantation, or to prevent allograft rejection, e.g., graft-versus-host disease (GVHD). In some embodiments, the subject has a dermatological disorder, liver disease (e.g., cirrhosis), hidradenitis, or experimental autoimmune encephalomyelitis. In some embodiments, the subject has renal 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 autoimmune thyroid disease, Graves' 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 method comprises administering to the subject an effective amount of a composition comprising an antibody or antigen-binding fragment thereof described herein.

[0240] As used herein, "effective amount" means an amount or dosage sufficient to bring about beneficial or desired results, including halting, regressing, slowing, or inhibiting the progression of a disease, e.g., an autoimmune disease or cancer. The effective amount will vary depending on, for example, the age and weight of the subject to whom the antibody, antigen-binding fragment, antibody-encoding polynucleotide, vector comprising the polynucleotide, and / or composition thereof is administered, the severity of the symptoms, and the route of administration, and thus administration may be determined individually.

[0241] An effective amount can be administered in one or more administrations. By way of example, an effective amount of an antibody or antigen-binding fragment is an amount sufficient to ameliorate, arrest, stabilize, reverse, inhibit, regress, and / or slow the progression of an autoimmune disease or cancer in a patient, or an amount sufficient to ameliorate, arrest, stabilize, reverse, regress, and / or slow the proliferation of cells (e.g., biopsy cells, any of the cancer cells described herein, or a cell line (e.g., a cancer cell line)) in vitro. As understood in the art, the effective amount of an antibody or antigen-binding fragment can vary depending on other factors, such as the patient's medical history and the type (and / or dosage) of antibody used, among other factors.

[0242] Effective amounts and schedules for administering the antibodies, antibody-encoding polynucleotides, and / or compositions disclosed herein may be determined empirically, and making such determinations is within the skill of one in the art. Those skilled in the art will understand that the dosage required to be administered will vary depending, for example, on the mammal receiving the antibodies, antibody-encoding polynucleotides, and / or compositions disclosed herein, the route of administration, the particular type of antibody, antibody-encoding polynucleotide, antigen-binding fragment, and / or composition disclosed herein used, and other drugs administered to the mammal. Guidance for selecting an appropriate dose of an antibody or antigen-binding fragment can be found in literature on the therapeutic use of antibodies and antigen-binding fragments, e.g., Handbook of Monoclonal Antibodies, Ferrone et al., eds., Noges Publications, Park Ridge, NJ, 1985, ch. 22 and pp. 303-357; Smith et al., Antibodies in Human Diagnosis and Therapy, Haber et al., eds., Raven Press, New York, 1977, pp. 365-389.

[0243] A typical daily dose of an effective amount of 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.

[0244] In any of the methods described herein, at least one antibody, antigen-binding fragment thereof, or pharmaceutical composition (e.g., any of the antibodies, antigen-binding fragments, or pharmaceutical compositions described herein), and optionally at least one additional therapeutic agent, may be administered to a subject at least once a week (e.g., once a week, twice a week, three times a week, four times a week, once a day, twice a day, or three times a day). In some embodiments, at least two different antibodies and / or antigen-binding fragments are administered in the same composition (e.g., 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 (e.g., 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 (e.g., a liquid composition containing at least one antibody or antigen-binding fragment and an oral solid composition containing at least one additional therapeutic agent). In some embodiments, at least one additional therapeutic agent is administered as a pill, tablet, or capsule. In some embodiments, at least one additional therapeutic agent is administered in a sustained release oral formulation.

[0245] In some embodiments, the one or more additional therapeutic agents may be administered to the subject before or after 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) is administered. 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 the periods of biological activity of the one or more additional therapeutic agents and the at least one antibody or antigen-binding fragment (e.g., an antibody or antigen-binding fragment described herein) overlap in the subject.

[0246] In some embodiments, a subject can be administered 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) over an extended period of time (e.g., for 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 determine the length of treatment period using any of the methods for diagnosing or tracking the effectiveness of treatment (e.g., observing at least one symptom of cancer) described herein. As described herein, a skilled medical professional may, based on an evaluation of the effectiveness of the treatment (e.g., using any of the methods described herein and known in the art), alter the identity and number (e.g., increase or decrease) of the antibodies or antigen-binding antibody fragments (and / or one or more additional therapeutic agents) administered to the subject, and may also adjust (e.g., increase or decrease) the dosage or frequency of administration of at least one antibody or antigen-binding antibody fragment (and / or one or more additional therapeutic agents) to the subject.

[0247] In some embodiments, one or more additional therapeutic agents may be administered to the subject. The additional therapeutic agents may include 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-Met inhibitor, an anaplastic lymphoma kinase (ALK) inhibitor, an inhibitor of phosphatidylinositol 3-kinase (PI3K), an Akt inhibitor, an mTOR inhibitor, a dual PI3K / mTOR inhibitor, a Bruton's tyrosine kinase (BTK) inhibitor, and an isocitrate dehydrogenase 1 (IDH1) and / or an isocitrate dehydrogenase 2 (IDH2) inhibitor. In some embodiments, the additional therapeutic agent is an indoleamine 2,3-dioxygenase-1 (IDO1) inhibitor (e.g., epacadostat).

[0248] In some embodiments, the additional therapeutic agent may comprise one or more inhibitors selected from the group consisting of a PD-1 inhibitor, an LSD1 inhibitor, an MDM2 inhibitor, a BCL2 inhibitor, a CHK1 inhibitor, an activated hedgehog signaling pathway inhibitor, and an agent that selectively degrades the estrogen receptor.

[0249] In some embodiments, the additional therapeutic agent is trabectedin, nab-paclitaxel, trebananib, pazopanib, cediranib, palbociclib, everolimus, fluoropyrimidine, IFL, regorafenib, leolysin, Alimta, Zykadia, Sutent, temsirolimus, axitinib, everolimus, sorafenib, Votrient, pazopanib, IMA-901, AGS-003 , cabozantinib, vinflunine, Hsp90 inhibitors, Ad-GM-CSF, temazolomide, IL-2, IFNa, vinblastine, thalomid, dacarbazine, cyclophosphamide, lenalidomide, azacitidine, lenalidomide, bortezomib, amrubicin, carfilzomib, pralatrexate, and enzastaurin.

[0250] In some embodiments, the additional therapeutic agents may comprise one or more therapeutic agents selected from the group consisting of an adjuvant, a TLR agonist, a tumor necrosis factor (TNF) alpha, 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 therapeutic target CX3CL1, a therapeutic target CXCL9, a therapeutic target CXCL10, a therapeutic target CCL5, an LFA-1 agonist, an ICAM1 agonist, and a PD-1 agonist.

[0251] In some embodiments, the subject is administered carboplatin, nab-paclitaxel, paclitaxel, cisplatin, pemetrexed, gemcitabine, FOLFOX, or FOLFIRI.

[0252] 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.

[0253] In one aspect, the present disclosure provides combination therapies. In some embodiments, an anti-CD79b antibody or antigen-binding fragment thereof (e.g., any antibody described herein) can be administered with an anti-CTLA4 antibody. Pharmaceutical Compositions and Routes of Administration

[0254] Also provided herein are pharmaceutical compositions containing at least one (e.g., one, two, three, or four) of the antibodies or antigen-binding fragments described herein. Two or more (e.g., 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.

[0255] Pharmaceutical compositions are formulated to match the intended route of administration (e.g., intravenous, intraarterial, intramuscular, intradermal, subcutaneous, or intraperitoneal). The compositions may contain a sterile diluent (e.g., sterile water or saline), fixed oils, polyethylene glycol, glycerin, propylene glycol, or other synthetic solvents, antibacterial or antifungal agents such as benzyl alcohol or methylparaben, chlorobutanol, phenol, ascorbic acid, thimerosal, or the like, antioxidants such as ascorbic acid or sodium bisulfite, chelating agents such as ethylenediaminetetraacetic acid, buffers such as acetates, citrates, or phosphates, and isotonicity agents such as sugars (e.g., dextrose), polyhydric alcohols (e.g., mannitol or sorbitol), or salts (e.g., sodium chloride), or any combination thereof. Liposomal suspensions can also be used as pharmaceutically acceptable carriers (see, e.g., U.S. Pat. No. 4,522,811). The composition preparation can be formulated and enclosed in ampoules, disposable syringes, or multiple dose vials. Where necessary (e.g., injectable formulations), proper fluidity can be maintained by the use of a coating such as lecithin or a surfactant. Absorption of the antibody or antigen-binding fragment thereof can be prolonged by including an agent that delays absorption (e.g., aluminum monostearate and gelatin). Alternatively, controlled release can be achieved by implants and microencapsulated delivery systems that can include biodegradable, biocompatible polymers (e.g., ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters, and polylactic acid, from Alza Corporation and Nova Pharmaceutical, Inc.).

[0256] Compositions containing any one or more of the antibodies or antigen-binding fragments described herein can be formulated for parenteral (e.g., intravenous, intraarterial, intramuscular, intradermal, subcutaneous, or intraperitoneal) administration in unit dosage form (i.e., a physically discrete unit containing a predetermined amount of active compound for ease of administration and uniformity of dosage).

[0257] Pharmaceutical compositions for parenteral administration are preferably sterile, substantially isotonic, and prepared under Good Manufacturing Practice (GMP) conditions. Pharmaceutical compositions can be provided in unit dosage form (i.e., single dose). Pharmaceutical compositions can be formulated using one or more physiologically acceptable carriers, diluents, excipients, or adjuvants. The formulation will vary depending on the route of administration selected. For injection, the antibody can be formulated in an aqueous solution, preferably a physiologically compatible buffer, to reduce discomfort at the injection site. The solution may contain formulating agents such as suspending agents, stabilizing agents, and / or dispersing agents. Alternatively, the antibody may be in lyophilized form prior to use, for use with a suitable vehicle, e.g., sterile, pyrogen-free water.

[0258] The toxicity and therapeutic efficacy of a composition can be determined by standard pharmaceutical procedures in cell cultures or experimental animals (e.g., monkeys). For example, 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 of LD50:ED50. Drugs that exhibit a high therapeutic index are preferred. If a drug exhibits undesirable side effects, care must be taken to minimize potential harm (i.e., reduce unwanted side effects). Toxicity and therapeutic efficacy may also be determined by other standard pharmaceutical procedures.

[0259] Data obtained from cell culture assays and animal studies can be used to formulate an appropriate dose 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) of the above antibodies or antigen-binding fragments thereof (e.g., any of the antibodies or antibody fragments described herein) is that amount that treats the disease in a subject (e.g., a human subject identified as having cancer) or identified as being at risk for the disease (e.g., a subject who previously had cancer but has now been cured) (e.g., a subject who has been cured of cancer) and reduces the severity, frequency, and / or duration of one or more symptoms of the disease in the subject (e.g., a human). The efficacy and dosage of any antibody or antigen-binding fragment described herein can be determined by a medical or veterinary professional using methods known in the art and by observing one or more symptoms of the disease in the subject (e.g., a human). Several factors can affect the dosage and timing required to effectively treat a subject (e.g., the severity of the disease or disorder, previous treatments, the general health and / or age of the subject, and the presence of other diseases).

[0260] Exemplary doses include milligram or microgram amounts of any antibody or antigen-binding fragment described herein per kilogram of subject body weight (e.g., about 1 μg / kg to about 500 mg / kg, about 100 μg / kg to about 500 mg / kg, about 100 μg / kg to about 50 mg / kg, about 10 μg / kg to about 5 mg / kg, about 10 μg / kg to about 0.5 mg / kg, or about 1 μg / kg to about 50 μg / kg). While these doses cover a wide range, one of skill in the art will recognize that therapeutic agents, including antibodies and antigen-binding fragments thereof, vary in potency and that effective amounts can be determined by methods known in the art. Typically, a relatively low dose is administered initially, and the attending medical or veterinary professional (for therapeutic uses) or researcher (if still in development) can gradually increase the dose until an appropriate response is obtained. In addition, it will be understood that the specific dose level for a particular subject will depend on a variety of factors, such as the activity of the particular compound used, the subject's age, weight, general health, sex, diet, time of administration, route of administration, excretion rate, and in vivo half-life of the antibody or antibody fragment.

[0261] The pharmaceutical compositions can be included in a container, pack, or dispenser together with instructions for administration.The present disclosure also provides methods for producing the antibodies or antigen-binding fragments thereof for the various uses described herein. [Example]

[0262] The present invention is further described by the following examples, which do not limit the scope of the invention described in the claims.

[0263] Example 1 Generation of anti-CD79b antibodies Immunization of rabbits with CD79b antigen To generate monoclonal antibodies against human CD79b, two New Zealand White rabbits were immunized with human CD79b ECD antigen (SEQ ID NO: 1, amino acids 29-159, his-tagged, from AcroBiosystems) using complete or incomplete Freund's adjuvant. Serum titers were monitored by ELISA after the second injection.

[0264] Screening of single B cells producing monoclonal antibodies against CD79b After 3–4 immunizations at 200 μg / injection per rabbit, rabbits with good titers (>1:100,000) were given a final booster injection, and spleens were harvested 7 days after the final injection.

[0265] Isolation of spleen cells from rabbits All procedures (except centrifugation) were performed in a biological safety cabinet. Rabbit spleens were harvested 7 days after the final booster injection. Spleen cells were prepared using a sterile cell strainer placed on 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 to the cell strainer. Specifically, the spleen was held between the forceps and dissected into small pieces, which were then pushed through the mesh of the cell strainer. The tissue fragments were washed with 10 mL of RPMI + 1% P / S. The spleen cells were transferred from the Petri dish to 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 × g for 5 min, 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 a final volume of 50 ml. The cells were centrifuged at 400 × g for 5 min, and the supernatant was aspirated. The cell pellet was resuspended in RPMI + 10% FBS + 1% P / S. The cells were centrifuged at 400 × g for 5 min, and the supernatant was aspirated. The pellet was resuspended in 15 ml of RPMI + 10% FBS + 1% P / S. The cells were pipetted through a 100 μm cell strainer into a 50 mL conical tube to remove cell clumps. The spleen cells were then seeded at the desired density (e.g., 4E6 cells / ml) in the appropriate medium and sorted. The remaining spleen cells were diluted to 6 × 10 in 90% serum + 10% DMSO. 7 Cells / vial (approximately 1.8 ml) were frozen overnight at −80° C. The frozen cells were transferred into a liquid nitrogen tank for long-term storage.

[0266] Antigen-specific B cell sorting For B cell sorting, freshly isolated or thawed spleen cells (approximately 2 x 10 8 Spleen cells were cultured overnight in B cell culture medium (RPMI-1640, 15% FBS, 1x HEPES, 1x 2-ME (2-mercaptoethanol), 1% penicillin / streptomycin) before sorting. Accordingly, a 96-well B cell feeding plate was prepared one day before sorting. On the day of sorting, suspended, loosely adherent spleen cells were collected by gently pipetting the medium against the culture surface of the flask. The cells were then transferred to a conical tube and centrifuged at 400 x g for 3 min. The cell pellet was washed twice with fluorescence-activated cell sorting (FACS) buffer (1x PBS + 0.5% BSA). Biotinylated antigen was added at 5 μg / ml (final concentration). The mixture was incubated at room temperature (RT) for 20 min. The staining mixture was then centrifuged at 400 x g for 3 min, and the cells were resuspended in FACS buffer. The cells were transferred to a 1.5 ml amber Eppendorf tube. The staining antibody mixture was then added to the cells. The staining mixture was incubated at 4°C for 15-30 min, followed by centrifugation at 400 x g for 3 min. The cell pellet was washed twice with FACS buffer. The washed cell pellet was diluted approximately 10 times with 1x PBS + 1% FBS. 7 The rabbits were resuspended at 1000 cells / ml. Antigen-specific single B cells were sorted into 96-well plates (20 plates per rabbit) using fluorescence-activated cell sorting. The 96-well B cell culture plates containing the sorted B cells were cultured at 37°C in 5% CO for 12 days.

[0267] Screening of single B cell cultures On day 8 after sorting, 15 μL of B cell culture supernatant was collected from each well for antigen-specific ELISA. Briefly, B cell culture supernatant was transferred to a 384-well plate coated with CD79b extracellular domain (ECD) and then blocked. Cells were incubated for 1 hour at room temperature and washed three times with PBS + 0.05% Tween-20. Secreted antibodies were detected with goat anti-rabbit IgG HRP + TMB substrate. B cell supernatants meeting the OD450 cutoff (>0.5 or 3-fold higher than preimmune serum) were then selected. Using FACS, the selected cells were (1) counterscreened against an N-terminal deletion CD79b variant (the first 13 amino acid residues were deleted from the N-terminus, SEQ ID NO: 2), (2) screened against cynomolgus monkey CD79b (SEQ ID NO: 3) for cross-species binding, and (3) screened against Daudi cells for cell surface binding.

[0268] An initial ELISA screening of supernatants from B cells sorted onto 40 plates (96-well plates) was performed for CD79b-specific antibodies, and approximately 230 CD79b antigen-specific positive B cell clones were identified.

[0269] On day 12 after sorting, B cell culture plates were centrifuged at 400 × g for 3 min. Supernatants from positive clones (with OD values ​​above the cutoff selected from the antigen-specific ELISA) were collected, and the cell pellets were stored in 100 μL DNA / RNA shield (Zymo Cat# R1100-250) in 250 μL PCR tubes. The collected supernatants were subjected to additional testing as described below.

[0270] Screening for CD79b-specific antibodies that bind to cell surface-expressed CD79b CD79b is a member of the B cell receptor complex. Due to epitope accessibility, it is expected that not all antibody clones that bind to CD79b by ELISA also bind to cell surface-expressed CD79b. CD79b-specific B cell clones identified by ELISA were subjected to cell surface binding assays with Daudi cells by FACS. Briefly, 50 μl of B cell supernatant (diluted 1:10 in FACS buffer, 1x PBS + 0.5% BSA) was incubated with 50,000 Daudi cells (plated in a 96-well plate) on ice for 1 h and washed twice with 150 μl of ice-cold FACS buffer. 100 μl of anti-rabbit-PE secondary antibody (Biolegend) was added, mixed, and incubated on ice for 30 min. Cells were washed three times with 150 μl of FACS buffer and finally resuspended in 100 μl of FACS buffer. 5,000 cells from each staining were collected and analyzed on a flow cytometer. Of approximately 230 ELISA-positive B cell clones, 12 clones were shown to bind to CD79b on the cell surface.

[0271] Recovery of VH and VL gene sequences from selected anti-CD79b clones DNA fragments encoding the heavy chain variable domain (VH) and light chain variable domain (VL) from B cell clones that exhibited high cell surface binding affinity for CD79b were amplified by 5' RACE (rapid amplification of cDNA ends), TOPO cloned, and sequenced.

[0272] Example 2 Generation of chimeric expression constructs To express a rabbit / human chimeric IgG1 antibody, the human IgG1 heavy chain constant region (CH1 to CH3, SEQ ID NO: 4) and human kappa light chain constant region (CL-kappa, SEQ ID NO: 5) were each synthesized and cloned into the pcDNA3.4 vector (Invitrogen). The heavy chain cloning vector pcDNA3.4-huIgG1-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, VH and VL sequences selected from a rabbit anti-CD79b antibody (Figure 22) were obtained by gene synthesis (Integrated DNA technology) and ligated to a secretory leader sequence (SEQ ID NO: 6) with overlapping sequences at both the 5' and 3' ends. Gibson assembly (NEB NEBuilder® HiFi DNA Assembly) was then performed to generate HC and LC expression plasmids. The assembled plasmids were transformed into competent E. coli (NEB® 5-alpha). Clones with the correct sequences were selected based on sequencing results (Elim Biopharm) and cultured in LB containing carbenicillin (100 μg / ml). Plasmids were purified (QIAGEN Plasmid Plus Kits), eluted with nuclease-free HO (Sigma), and stored at -80°C.

[0273] Example 3 Expression and purification of chimeric anti-CD79b antibodies The recombinant chimeric antibody was expressed in CHO cells (ExpiCHO™ Expression System, Gibco) by transfecting them with pcDNA3.4-huIgG1-Hc and pcDNA3.4-huKappa-Lc containing the paired VH and VL sequences. ExpiCHO cells were cultured in ExpiCHO expression medium and 0.3–6 × 10 6In a 125 ml baffled flask, 25 ml of fresh ExpiCHO cells (6 × 10 cells / ml) were added and maintained at 37 °C, 125 rpm, 5% CO2, and 80% humidity. 6 / ml, viability >95%, prepared the day before transfection) 6 Cells were seeded at 1 / ml. 1 ml of serum-free medium (OptiPRO™ SFM, Gibco) containing pcDNA3.4-huIgG1-Hc and pcDNA3.4-huKappa-Lc (12 μg of each plasmid) was mixed well with 1 ml of OptiPRO™ SFM containing 80 μl of transfection reagent (ExpiFectamine™ CHO Reagent, Gibco) by pipetting. The transfection mixture was then added to 25 ml of ExpiCHO cells and cultured at 37°C. The next day, 150 μl of ExpiFectamine™ CHO Enhancer, 6 ml of ExpiCHO™ Feed, and 1X penicillin-streptomycin (Gibco) were added, and the transfection culture was then transferred to a 32°C incubator. The cell density and viability of the transfected cultures were monitored, and the IgG1 antibody titer in the medium was monitored with a biolayer interferometry (BLI) instrument equipped with a protein A biosensor (Gator prime, Gator Bio).

[0274] After 5 days, the culture medium containing the secreted IgG1 antibody was collected (centrifugation at 2000 g for 10 minutes), filtered (Thermo Scientific™ Nalgene™ Rapid-Flow™ Sterile Disposable Filter), and further purified using a gravity-flow column (Bio-Rad) packed with Protein A resin (TOYOPEARL AF-rProtein A Hc-650F). The IgG1 antibody was eluted with 3.5 ml of glycine-HCl (100 mM, pH 2.7), immediately neutralized with 1 M Tris-HCl (pH 8.5), dialyzed in 1× PBS buffer (pH 7.2) using Thermo Scientific™ Slide-A-Lyzer™ G2 Dialysis Cassettes (20K MWCO), and stored at 4°C. The concentration of the purified IgG1 antibody was determined using a NanoDrop™ One / One C The quality of the IgG1 antibody was examined by SDS-PAGE gel under both denaturing and non-denaturing conditions, as measured by Microvolume UV-Vis Spectrophotometer (Thermo Scientific™).

[0275] Example 4 Binding Affinities of Anti-CD79b Antibodies to Human and Cynomolgus Monkey CD79b Recombinant Proteins as Measured by ELISA and BLI The binding affinity of anti-CD79b antibodies to human and cynomolgus monkey CD79b recombinant proteins was tested by ELISA. Human or cynomolgus monkey CD79b recombinant proteins at 1 μg / ml (in PBS buffer) were coated onto ELISA plates and left overnight. The ELISA plates were washed and blocked with blocking buffer (PBS + 1% BSA), followed by incubation with serially diluted anti-CD79b primary antibodies. Anti-CD79b antibody binding was quantified using an anti-human IgG HRP secondary antibody (Biolegend Catalog # 410902) and HRP substrate. The ELISA binding affinities of anti-CD79b antibodies to human and cynomolgus monkey CD79b recombinant proteins are shown in Table 1, Figure 1, and Figure 2.

[0276] The binding affinity of anti-CD79b antibodies to human CD79b recombinant protein was tested by BLI. 10 μg / ml of anti-CD79b antibody was captured with an anti-human IgG Fc probe (Gator Bio Catalog # 160024). Association and dissociation of serially diluted human CD79b recombinant protein (146 nM to 0 nM, 2-fold dilutions in PBS + 0.05% Tween-20) was measured. Absolute kDa was determined by applying a 1:1 binding model (Global Rmax unlinked). The BLI binding affinities of anti-CD79b antibodies to human CD79b recombinant protein are shown in Table 1 and Figure 3. Polatuzumab was included for comparison. For ch44G2, the BLI data showed a K on of 3.77E+05, but an undetectable k off . This suggests that ch44G2 has strong binding affinity to CD79b. [Table 1]

[0277] Example 5 Internalization of anti-CD79b antibodies The internalization of anti-CD79b antibodies was evaluated. Approximately 50,000 Ramos cells (per time point) were incubated with 20 μg / ml of labeled anti-CD79b antibody and incubated at 37°C. At different time points, the cells were washed, and the presence of anti-CD79b antibody-binding receptors was detected using an anti-human IgG PE secondary antibody (Jackson Research Catalog # 109-116-170). For analysis, the mean fluorescence intensity (MFI(PE)) of each antibody was normalized to the respective zero time point (100%), and the decrease in percentage MFI(PE) over time was plotted. As shown in Figure 4, all of the screened anti-CD79b antibodies were internalized more slowly than polatuzumab. Among them, ch23D8, ch44G2, ch48H10, and ch57B9 showed significantly slower internalization than the other antibodies.

[0278] Example 6 Quantification of tumor cell surface CD79b antigen density To estimate the CD79b antigen expression levels on the surface of malignant B tumor cells and normal B cells, cell lines and PBMCs from two healthy donors were stained with a saturating concentration of the anti-CD79b antibody ch44G2 for 30 min on ice. After washing with PBS, the cells were stained with a secondary PE-labeled anti-human IgG (Invitrogen, Cat: 12-4998-82) for 30 min on ice. The cells were then washed with PBS and resuspended in FACS buffer for flow cytometry analysis using Cytek northern lights. Results were analyzed and graphed 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. [Table 2]

[0279] Example 7 Malignant B-cell line binding assay The binding affinity of anti-CD79b antibodies to malignant B cell lines was tested. Polatuzumab and IgG1 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 IgG1 (Biolegend, Cat#: 403502) at different concentrations (1:3 serial dilutions starting from 40 nM) on ice for 30 min and then washed twice with 200 μl of PBS. Next, cells were incubated with 100 μl of 1:1000 diluted anti-human IgG1-PE (Invitrogen, cat: 12-4998-82) on ice for 30 min and washed three times with 200 μl of PBS before flow cytometry analysis. As shown in Figures 6–10, the anti-CD79b antibodies ch23D8, ch44G2, ch48H10, and ch57B9 exhibited higher cell surface binding affinity (lower EC50) than polatuzumab for BJAB (Figure 6), Ramos (Figure 7), Daudi (Figure 8), SU-DHL-4 (Figure 9), and Nalm-6 (Figure 10). The results indicated that ch23D8, ch44G2, ch48H10, and ch57B9 could bind to malignant B cell lines at both high and low CD79b antigen densities.

[0280] Example 8 Endogenous B Cell Binding Assay The binding affinity of anti-CD79b antibodies to endogenous B cells was tested. Polatuzumab and an IgG1 control were used as positive and negative controls, respectively. PBMCs from four donors (Stanford Blood Center) at 200,000 cells / well in 96-well plates were incubated with anti-CD79b antibodies (ch23D8, ch44G2, ch48H10, and polatuzumab) and IgG1 (Biolegend, Cat#: 403502) at different concentrations (1:5 serial dilutions starting from 50 nM) on ice for 30 min and then washed twice with 200 μl of PBS. The cells were then incubated with 100 μl of a mixture of anti-human IgG1-PE (Invitrogen, Cat#: 12-4998-82) diluted 1:1000 and CD19-BV421 (Biolegend, Cat#: 302230, diluted 1:400) on ice for 30 min and washed three times with 200 μl of PBS before flow cytometry analysis. As shown in Figures 11-14, ch44G2, ch48H10, and ch23D8 exhibited higher cell surface binding affinity to endogenous B cells than polatuzumab in all four different donors.

[0281] Example 9 PBMC Binding Assay of CLL Patients A cell-based binding assay was performed to measure the binding affinity of anti-CD79b antibodies to cell surface CD79b on B lymphocytes from chronic lymphocytic leukemia (CLL) patients. Polatuzumab and an IgG1 control were used as positive and negative controls, respectively. PBMCs from CLL patients were purchased from Bioscience. FACS analysis showed that 95% of B lymphocytes (CD19+) in PBMCs were positive. Specifically, 2.5 × 10 cells were cultured in 50 μl of FACS buffer (1 × PBS + 2% BSA + 2 mM EDTA). 4PBMC cells were seeded into each well of a V-bottom 96-well plate. Next, 50 μl of serially diluted anti-CD79b antibodies (ch22D10, ch23D8, ch29C3, ch44G2, ch48H10, ch57B9, or polatuzumab) or IgG1 was added to each well. The mixture was incubated on ice for 30 minutes and then washed twice with FACS buffer. The cells were resuspended in 100 μl of FACS buffer containing PE-conjugated goat anti-human IgG Fc (1:1000) and anti-human CD19 (BV421) and incubated on ice in the dark for 30 minutes. After washing twice with FACS buffer, the cells were resuspended in 100 μl of FACS buffer and analyzed on a Cytek cytometer. As shown in Figures 15 and 16, ch23D8, ch44G2, ch48H10 and ch57B9 had stronger binding to B lymphocytes of CLL patients than polatuzumab.

[0282] Example 10 CD79b mAbs that bind to short and long isoforms of CD79b Surface binding of anti-CD79b antibodies to both the long and short isoforms of CD79b was performed. Polatuzumab was used as a positive control. Approximately 2 million Nalm-6 cells were electroporated with expression plasmids encoding the short (Nalm-6+ short isoform) and long (Nalm-6+ long isoform) isoforms of CD79b, respectively. After 48 hours, cells were stained with the indicated anti-CD79b antibodies (ch23D8, ch44G2, or polatuzumab) and detected with anti-IgM-APC (BD Biosciences, Catalog # 551062). As shown in Figures 17A-17B, ch23D8 and ch44G2 have strong binding affinity for both the long and short isoforms of CD79b.

[0283] Example 11 Humanization of anti-CD79b antibodies Four rabbit anti-human CD79b monoclonal antibody clones, 23D8, 44G2, 48H10, and 57B9, were humanized by grafting the CDRs of the primary antibodies onto selected human germline frameworks that were closest to the rabbit frameworks identified by 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 in both the framework and CDRs. To maintain canonical loop structures and the light / heavy chain interface, specific human germline framework residues were backmutated to the corresponding rabbit residues (Padlan Mol. Immunol., 1994, 31:169; Foote and Winter JMB, 1992, 224:487; Padlan Mol. Immunol., 1994, 31:169). Humanization generated the hu23D8, hu44G2, hu48H10, and hu57B9 humanized antibodies.

[0284] The thermal stability of the humanized antibody clones was assessed by Nano DSF (Table 3). The humanized antibodies were confirmed to bind to recombinant human CD79b ECD in ELISA (Figure 18) and to cell lines expressing endogenous CD79b (Figure 19).

[0285] The results showed that the humanized anti-CD79b antibody exhibited the same technical effects as the chimeric anti-CD79b antibody, such as high affinity for CD79b, slow internalization, high binding to malignant B cell lines at both high and low CD79b antigen densities, high cell surface binding affinity to endogenous B cells, high binding to B lymphocytes from CLL patients, and strong binding affinity to both the long and short isoforms of CD79b. [Table 3] Other embodiments

[0286] While the present invention has been described with reference to its detailed description, it is understood that the foregoing description is by way of example and not as a limitation on the scope of the invention, which is defined by the appended claims. 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), 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 amino acid sequence, and the VH CDR3 region comprises an amino acid sequence that is at least 80% identical to a selected VH CDR3 amino acid sequence; a light chain variable region (VL) comprising CDR1, 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 selected VH CDR1, 2, and 3 amino acid sequences and the selected VL CDR1, 2, and 3 amino acid sequences are (1) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 9, 11, and 13, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 14 to 16, respectively; (2) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 19, 21, and 23, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 24 to 26, respectively; (3) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 29, 31, and 33, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 34 to 36, respectively; (4) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 39, 41, and 43, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 44 to 46, respectively; (5) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 49, 51, and 53, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 54 to 56, respectively; (6) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 59, 61, and 63, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 64 to 66, respectively; (7) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 10, 12, and 13, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 14 to 16, respectively; (8) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 20, 22, and 23, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 24 to 26, respectively; (9) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 30, 32, and 33, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 34 to 36, respectively; (10) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 40, 42, and 43, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 44 to 46, respectively; (11) The selected VH CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 50, 52, and 53, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are shown in SEQ ID NOs: 54 to 56, respectively; and (12) An antibody or antigen-binding fragment thereof, wherein the selected VH CDR1, 2, and 3 amino acid sequences are set forth in SEQ ID NOs: 60, 62, and 63, respectively, and the selected VL CDR1, 2, and 3 amino acid sequences are set forth in SEQ ID NOs: 64 to 66, respectively.

2. The antibody or antigen-binding fragment thereof of claim 1, wherein, according to the Kabat definition, the VH comprises CDR1, CDR2, and CDR3 having the amino acid sequences set forth in SEQ ID NOs: 9, 11, and 13, respectively, and the VL comprises CDR1, CDR2, and CDR3 having the amino acid sequences set forth in SEQ ID NOs: 14 to 16, respectively.

3. The antibody or antigen-binding fragment thereof of claim 1, wherein, according to the Kabat definition, the VH comprises CDR1, CDR2, and CDR3 having the amino acid sequences set forth in SEQ ID NOs: 19, 21, and 23, respectively, and the VL comprises CDR1, CDR2, and CDR3 having the amino acid sequences set forth in SEQ ID NOs: 24 to 26, respectively.

4. The antibody or antigen-binding fragment thereof of claim 1, wherein, according to the Kabat definition, the VH comprises CDR1, CDR2, and CDR3 having the amino acid sequences set forth in SEQ ID NOs: 29, 31, and 33, respectively, and the VL comprises CDR1, CDR2, and CDR3 having the amino acid sequences set forth in SEQ ID NOs: 34 to 36, respectively.

5. The antibody or antigen-binding fragment thereof of claim 1, wherein, according to the Kabat definition, the VH comprises CDR1, CDR2, and CDR3 having the amino acid sequences set forth in SEQ ID NOs: 39, 41, and 43, respectively, and the VL comprises CDR1, CDR2, and CDR3 having the amino acid sequences set forth in SEQ ID NOs: 44 to 46, respectively.

6. The antibody or antigen-binding fragment thereof of claim 1, wherein, according to the Kabat definition, the VH comprises CDR1, CDR2, and CDR3 having the amino acid sequences set forth in SEQ ID NOs: 49, 51, and 53, respectively, and the VL comprises CDR1, CDR2, and CDR3 having the amino acid sequences set forth in SEQ ID NOs: 54 to 56, respectively.

7. The antibody or antigen-binding fragment thereof of claim 1, wherein, according to the Kabat definition, the VH comprises CDR1, CDR2, and CDR3 having the amino acid sequences set forth in SEQ ID NOs: 59, 61, and 63, respectively, and the VL comprises CDR1, CDR2, and CDR3 having the amino acid sequences set forth in SEQ ID NOs: 64 to 66, respectively.

8. The antibody or antigen-binding fragment thereof of claim 1, wherein, according to the Chothia definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 10, 12, and 13, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 14 to 16, respectively.

9. According to the Chothia definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 20, 22, and 23, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 24 to 26, respectively. The antibody or antigen-binding fragment thereof of claim 1.

10. According to the Chothia definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 30, 32, and 33, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 34 to 36, respectively. The antibody or antigen-binding fragment thereof of claim 1.

11. According to the Chothia definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 40, 42, and 43, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 44 to 46, respectively. The antibody or antigen-binding fragment thereof of claim 1.

12. According to the Chothia definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 50, 52, and 53, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 54 to 56, respectively. The antibody or antigen-binding fragment thereof of claim 1.

13. According to the Chothia definition, the VH comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 60, 62, and 63, respectively, and the VL comprises CDR1, 2, and 3 having the amino acid sequences set forth in SEQ ID NOs: 64 to 66, respectively. The antibody or antigen-binding fragment thereof of claim 1.

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

15. 15. The antibody or antigen-binding fragment thereof of 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-arm antibody, and / or a multispecific antibody (e.g., a bispecific antibody).

16. The antibody or antigen-binding fragment thereof of 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. 1. A nucleic acid comprising a polynucleotide encoding a polypeptide, said polypeptide comprising: (1) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 9, 11, and 13, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 8; and (2) an immunoglobulin light chain or fragment thereof comprising a VL comprising complementarity-determining regions (CDRs) 1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 14 to 16, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 7; and (3) an immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 19, 21, and 23, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 18; and (4) An immunoglobulin light chain or fragment thereof comprising a VL comprising complementarity-determining regions (CDRs) 1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 24 to 26, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 17; and (5) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 29, 31, and 33, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 28; and (6) An immunoglobulin light chain or fragment thereof comprising a VL comprising CDR1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 34 to 36, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 27; and (7) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 39, 41, and 43, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 38; and (8) An immunoglobulin light chain or fragment thereof comprising a VL comprising CDR1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 44 to 46, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 37; and (9) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 49, 51, and 53, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 48; and (10) An immunoglobulin light chain or fragment thereof comprising a VL comprising CDR1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 54 to 56, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 47; and (11) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 59, 61, and 63, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 58; and (12) An immunoglobulin light chain or fragment thereof comprising a VL comprising CDR1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 64 to 66, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 57; and (13) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 10, 12, and 13, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 8; and (14) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 20, 22, and 23, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 18; and (15) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 30, 32, and 33, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 28; and (16) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 40, 42, and 43, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 38; and (17) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 50, 52, and 53, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 48; and (18) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 60, 62, and 63, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 58; and (19) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 19, 21, and 23, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 70; and (20) An immunoglobulin light chain or fragment thereof comprising a VL comprising complementarity-determining regions (CDRs) 1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 24 to 26, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 69; and (21) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 20, 22, and 23, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 70; and (22) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 39, 41, and 43, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 72; and (23) An immunoglobulin light chain or fragment thereof comprising a VL comprising CDR1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 44 to 46, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 71; and (24) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 40, 42, and 43, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 72; and (25) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 49, 51, and 53, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 73; and (26) An immunoglobulin light chain or fragment thereof comprising a VL comprising CDR1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 54 to 56, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 74; and (27) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 50, 52, and 53, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 73; and (28) An immunoglobulin heavy chain or fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 59, 61, and 63, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO: 76; and (29) An immunoglobulin light chain or fragment thereof comprising a VL comprising CDR1, 2, and 3 each comprising the amino acid sequences set forth in SEQ ID NOs: 64 to 66, wherein the VL binds to CD79b when paired with a VH comprising the amino acid sequence set forth in SEQ ID NO: 75; and (30) A nucleic acid comprising an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising complementarity-determining regions (CDRs) 1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 60, 62, and 63, respectively, wherein the VH binds to CD79b when paired with a light chain variable region (VL) comprising the amino acid sequence set forth in SEQ ID NO:

76.

18. 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 comprising a VL comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 14 to 16, respectively.

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 comprising a VL comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 24 to 26, respectively.

20. 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 comprising a VL comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 34 to 36, respectively.

21. 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 comprising a VL comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 44 to 46, respectively.

22. 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 comprising a VL comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 54 to 56, respectively.

23. 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 comprising a VL comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 64-66, respectively.

24. 18. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 9, 11, and 13, respectively.

25. 18. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 19, 21, and 23, respectively.

26. 18. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 29, 31, and 33, respectively.

27. 18. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 39, 41, and 43, respectively.

28. 18. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 49, 51, and 53, respectively.

29. 18. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 59, 61, and 63, respectively.

30. 18. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 10, 12, and 13, respectively.

31. 18. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 20, 22, and 23, respectively.

32. 18. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 30, 32, and 33, respectively.

33. 18. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 40, 42, and 43, respectively.

34. 18. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 50, 52, and 53, respectively.

35. 18. The nucleic acid of claim 17, wherein the nucleic acid comprises a polynucleotide encoding a polypeptide comprising an immunoglobulin heavy chain or a fragment thereof comprising a VH comprising CDR1, 2, and 3 comprising the amino acid sequences set forth in SEQ ID NOs: 60, 62, and 63, respectively.

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

37. 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., a human IgG1 heavy chain CH1, CH2, and / or CH3, a human IgG2 heavy chain CH1, CH2, and / or CH3, or a 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. 38. The nucleic acid of any one of claims 17 to 37, wherein the nucleic acid encodes a single-chain variable fragment (scFv), a one-arm antibody, a multispecific antibody (e.g., a bispecific antibody), or a chimeric antigen receptor (CAR).

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

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

41. 40. A vector comprising two of the nucleic acids of any one of claims 17 to 39, which together encode a VL region and a VH region that bind to CD79b.

42. A pair of vectors, each of which contains one of the nucleic acids of any one of claims 17 to 39, and which together encode a VL region and a VH region that bind to CD79b.

43. 43. A cell comprising a vector according to claim 41 or 41, or a pair of vectors according to claim 42.

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

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

46. A cell comprising two of the nucleic acids of any one of claims 17 to 39.

47. The cell of claim 46, wherein the two nucleic acids both encode a VL region and a VH region that bind to CD79b.

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

49. An antibody or antigen-binding fragment thereof that binds to CD79b, a heavy chain variable region (VH) comprising an amino acid sequence that is at least 90% identical to a selected VH sequence, and a light chain variable region (VL) comprising 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 (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) An antibody or antigen-binding fragment thereof, wherein the selected VH sequence is SEQ ID NO: 57 or 75, and the selected VL sequence is SEQ ID NO: 58 or 76.

50. 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. 50. 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. 50. 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. 50. 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. 50. 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. 50. 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. 50. 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. 50. 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. 50. 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. 50. 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, a heavy chain variable region (VH) comprising VH CDR1, 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 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 (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) An antibody or antigen-binding fragment thereof, wherein the selected VH sequence is SEQ ID NO: 57 or 75, and the selected VL sequence is SEQ ID NO: 58 or 76.

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

62. 62. The antibody or antigen-binding fragment thereof of any one of claims 49 to 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-arm antibody, and / or a multispecific antibody (e.g., a bispecific antibody).

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

64. 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 to 16 and 49 to 63.

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

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

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

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

69. 68. A method of treating a subject having cancer, 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 to 16 and 49 to 65, the CAR of claim 66, or the antibody-drug conjugate of claim 67 or 68.

70. 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. 70. The method of claim 69, wherein the cancer is non-Hodgkin's 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. 70. 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. 1. A method for reducing the rate of tumor growth, comprising: A method comprising contacting tumor cells with an effective amount of a composition comprising the antibody or antigen-binding fragment thereof of any one of claims 1 to 16 and 49 to 65, the CAR of claim 66, or the antibody-drug conjugate of claim 67 or 68.

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

75. 1. A method of increasing an immune response in a subject, comprising:

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

76. 67. A method for treating a subject having an autoimmune disease, 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 to 16 and 49 to 65, the CAR of claim 66, or the antibody-drug conjugate of claim 67 or 68.

77. 77. The method of claim 76, wherein the autoimmune disease is selected from 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 arteritis, cold agglutinin disease, warm autoimmune hemolytic anemia, and antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, granulomatosis with polyangiitis (GPA) (Wegener's granulomatosis), microscopic polyangiitis (MPA), inflammatory bowel disease (IBD), or autoreactive pancreatitis.

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

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

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

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