SIRPα binding proteins and methods of use thereof

Abstract

Provided herein are compositions, methods, and uses involving antibodies that specifically bind to signal regulatory protein-α (SIRPα) and modulate SIRPα activity.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 737,782, filed September 27, 2018, and U.S. Provisional Patent Application No. 62 / 853,997, filed May 29, 2019, the disclosures of which are incorporated herein by reference in their entireties. 1. Technical Field

[0003] Provided herein are compositions, methods, and uses involving antibodies that specifically bind to signal regulatory protein-α (SIRPα) and modulate SIRPα activity. 2. Summary of the Invention

[0004] The present disclosure provides proteins that bind to SIRPα (e.g., human SIRPα, SEQ ID NO: 146), including binding proteins, such as antibodies that bind to SIRPα. Such binding proteins, including antibodies, can bind to SIRPα polypeptides, SIRPα fragments and / or SIRPα epitopes. Such binding proteins, including antibodies, can be antagonists or SIRPα blocking antibodies that compete with SIRPα ligands (e.g., CD47) for interaction with SIRPα. In some embodiments, an antibody is provided herein. In other embodiments, an antigen-binding fragment of an antibody is provided herein.

[0005] In one aspect, the present invention provides an antibody or an antigen-binding fragment thereof that (a) binds to a human SIRPα epitope recognized by an antibody comprising a light chain variable region having the amino acid sequence of SEQ ID NO: 67 and a heavy chain variable region having the amino acid sequence of SEQ ID NO: 80; or (b) competes for binding to human SIRPα with an antibody comprising a light chain variable region having the amino acid sequence of SEQ ID NO: 67 and a heavy chain variable region having the amino acid sequence of SEQ ID NO: 80.

[0006] On the other hand, provided herein is an antibody or antigen-binding fragment thereof that binds to SIRPα, wherein the antibody or antigen-binding fragment thereof comprises: (a) a light chain variable region (VL) comprising a VL complementarity determining region 1 (CDR1), a VL CDR2, and a VL CDR3 of any one of antibodies SIRPAB-11, SIRPAB-12, SIRPAB-1, SIRPAB-2, SIRPAB-3, SIRPAB-4, SIRPAB-5, SIRPAB-6, SIRPAB-7, SIRPAB-8, SIRPAB-9, SIRPAB-10, or SIRPAB-13 as described in Table 1. CDR3; and / or (b) a heavy chain variable region (VH) comprising a VH complementarity determining region 1 (CDR1), a VH CDR2, and a VH CDR3 of any one of antibodies SIRPAB-11, SIRPAB-12, SIRPAB-1, SIRPAB-2, SIRPAB-3, SIRPAB-4, SIRPAB-5, SIRPAB-6, SIRPAB-7, SIRPAB-8, SIRPAB-9, SIRPAB-10, or SIRPAB-13 as described in Table 2.

[0007] In some embodiments, the antibodies or antigen-binding fragments thereof provided herein comprise: (a) a light chain variable region (VL) further comprising the VL framework 1 (FR1), VL FR2, VL FR3, and VL FR4 of any one of antibodies SIRPAB-11, SIRPAB-12, SIRPAB-1, SIRPAB-2, SIRPAB-3, SIRPAB-4, SIRPAB-5, SIRPAB-6, SIRPAB-7, SIRPAB-8, SIRPAB-9, SIRPAB-10, or SIRPAB-13 as described in Table 3. and / or (b) a heavy chain variable region (VH) further comprising the VH framework 1 (FR1), VH FR2, VH FR3, and VH FR4 of any one of antibodies SIRPAB-11, SIRPAB-12, SIRPAB-1, SIRPAB-2, SIRPAB-3, SIRPAB-4, SIRPAB-5, SIRPAB-6, SIRPAB-7, SIRPAB-8, SIRPAB-9, SIRPAB-10, or SIRPAB-13 as described in Table 4.

[0008] In certain embodiments, the antibodies or antigen-binding fragments thereof provided herein comprise: VL CDR1, VL CDR2, and VL CDR3 comprising the amino acid sequences of SEQ ID NOs: 62, 63, and 65, respectively; and VH CDR1, VH CDR2, and VH CDR3 comprising the amino acid sequences of SEQ ID NOs: 78, 69, and 57, respectively.

[0009] In some embodiments, the antibodies or antigen-binding fragments thereof provided herein comprise: VL CDR1, VL CDR2, and VL CDR3 comprising the amino acid sequences of SEQ ID NOs: 62, 63, and 65, respectively; and VH CDR1, VH CDR2, and VH CDR3 comprising the amino acid sequences of SEQ ID NOs: 82, 83, and 57, respectively.

[0010] In certain embodiments, the antibody or antigen-binding fragment thereof comprises a VL comprising the amino acid sequence of SEQ ID NO: 18. In some embodiments, the antibody or antigen-binding fragment thereof comprises a VL comprising the amino acid sequence of SEQ ID NO: 46. In certain embodiments, the antibody or antigen-binding fragment thereof comprises a VL comprising the amino acid sequence of SEQ ID NO: 67.

[0011] In some embodiments, the antibody or antigen-binding fragment thereof comprises a VH comprising the amino acid sequence of SEQ ID NO: 9. In certain embodiments, the antibody or antigen-binding fragment thereof comprises a VH comprising the amino acid sequence of SEQ ID NO: 22. In some embodiments, the antibody or antigen-binding fragment thereof comprises a VH comprising the amino acid sequence of SEQ ID NO: 27. In certain embodiments, the antibody or antigen-binding fragment thereof comprises a VH comprising the amino acid sequence of SEQ ID NO: 32. In some embodiments, the antibody or antigen-binding fragment thereof comprises a VH comprising the amino acid sequence of SEQ ID NO: 36. In certain embodiments, the antibody or antigen-binding fragment thereof comprises a VH comprising the amino acid sequence of SEQ ID NO: 42. In some embodiments, the antibody or antigen-binding fragment thereof comprises a VH comprising the amino acid sequence of SEQ ID NO: 50. In some embodiments, the antibody or antigen-binding fragment thereof comprises a VH comprising the amino acid sequence of SEQ ID NO: 60. In certain embodiments, the antibody or antigen-binding fragment thereof comprises a VH comprising the amino acid sequence of SEQ ID NO: 71. In some embodiments, the antibody or antigen-binding fragment thereof comprises a VH comprising the amino acid sequence of SEQ ID NO: 76. In certain embodiments, the antibody or antigen-binding fragment thereof comprises a VH comprising the amino acid sequence of SEQ ID NO: 80. In some embodiments, the antibody or antigen-binding fragment thereof comprises a VH comprising the amino acid sequence of SEQ ID NO: 85. In certain embodiments, the antibody or antigen-binding fragment thereof comprises a VH comprising the amino acid sequence of SEQ ID NO: 90.

[0012] In other embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a VL comprising the amino acid sequence of SEQ ID NO: 18; and (b) a VH comprising the amino acid sequence of SEQ ID NO: 9. In certain embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a VL comprising the amino acid sequence of SEQ ID NO: 18; and (b) a VH comprising the amino acid sequence of SEQ ID NO: 22. In another embodiment, the antibody or antigen-binding fragment thereof comprises: (a) a VL comprising the amino acid sequence of SEQ ID NO: 18; and (b) a VH comprising the amino acid sequence of SEQ ID NO: 27. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a VL comprising the amino acid sequence of SEQ ID NO: 18; and (b) a VH comprising the amino acid sequence of SEQ ID NO: 32. In certain embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a VL comprising the amino acid sequence of SEQ ID NO: 18; and (b) a VH comprising the amino acid sequence of SEQ ID NO: 36. In other embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a VL comprising the amino acid sequence of SEQ ID NO: 46; and (b) a VH comprising the amino acid sequence of SEQ ID NO: 42. In another embodiment, the antibody or antigen-binding fragment thereof comprises: (a) a VL comprising the amino acid sequence of SEQ ID NO: 46; and (b) a VH comprising the amino acid sequence of SEQ ID NO: 50. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a VL comprising the amino acid sequence of SEQ ID NO: 67; and (b) a VH comprising the amino acid sequence of SEQ ID NO: 60. In certain embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a VL comprising the amino acid sequence of SEQ ID NO: 67; and (b) a VH comprising the amino acid sequence of SEQ ID NO: 71. In other embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a VL comprising the amino acid sequence of SEQ ID NO: 67; and (b) a VH comprising the amino acid sequence of SEQ ID NO: 76. In another embodiment, the antibody or antigen-binding fragment thereof comprises: (a) a VL comprising the amino acid sequence of SEQ ID NO: 67; and (b) a VH comprising the amino acid sequence of SEQ ID NO: 80. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a VL comprising the amino acid sequence of SEQ ID NO: 67; and (b) a VH comprising the amino acid sequence of SEQ ID NO: 85. In certain embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a VL comprising the amino acid sequence of SEQ ID NO: 67; and (b) a VH comprising the amino acid sequence of SEQ ID NO: 90.

[0013] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a VL comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 18, 46, and 67; and (b) a VH comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 9, 22, 27, 32, 36, 42, 50, 60, 71, 76, 80, 85, and 90.

[0014] In other embodiments, the antibody or antigen-binding fragment thereof comprises a human IgG1 Fc region or a mutant thereof. In another embodiment, the antibody or antigen-binding fragment thereof comprises a human IgG1-K322A Fc region. In some embodiments, the antibody or antigen-binding fragment thereof comprises a human IgG1-AAS Fc region.

[0015] In some embodiments, the antibody or antigen-binding fragment thereof comprises a human IgG4 Fc region or a mutant thereof. In certain embodiments, the antibody or antigen-binding fragment thereof comprises a human IgG4β Fc region. In other embodiments, the antibody or antigen-binding fragment thereof comprises a human IgG4PE Fc region. In another embodiment, the antibody or antigen-binding fragment thereof comprises a heavy chain Fc region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 144, 155-159.

[0016] In some embodiments, the antibody or antigen-binding fragment thereof comprises a light chain constant region comprising the amino acid sequence of SEQ ID NO:211.

[0017] In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain constant region comprising the amino acid sequence of SEQ ID NO: 211; and (b) a heavy chain Fc region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 144, 155-159.

[0018] In some embodiments, the antibody or antigen-binding fragment thereof comprises a light chain comprising the amino acid sequence of SEQ ID NO: 143. In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 142. In other embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 143; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 142.

[0019] In some embodiments, the antibody or antigen-binding fragment thereof comprises a light chain comprising the amino acid sequence of SEQ ID NO: 200. In some embodiments, the antibody or antigen-binding fragment thereof comprises a light chain comprising the amino acid sequence of SEQ ID NO: 202. In some embodiments, the antibody or antigen-binding fragment thereof comprises a light chain comprising the amino acid sequence of SEQ ID NO: 143. In some embodiments, the antibody or antigen-binding fragment thereof comprises a light chain comprising the amino acid sequence of SEQ ID NO: 208. In some embodiments, the antibody or antigen-binding fragment thereof comprises a light chain comprising the amino acid sequence of SEQ ID NO: 209. In some embodiments, the antibody or antigen-binding fragment thereof comprises a light chain comprising the amino acid sequence of SEQ ID NO: 210. In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 212. In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 213. In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 214. In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 215. In certain embodiments, an antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 216. In certain embodiments, an antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 217. In certain embodiments, an antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 218. In certain embodiments, an antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 219. In certain embodiments, an antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 220. In certain embodiments, an antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 221. In certain embodiments, an antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 142. In certain embodiments, an antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 204. In certain embodiments, an antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 222. In certain embodiments, an antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 223. In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 207. In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 117.In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 110. In certain embodiments, the antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence of SEQ ID NO:148.

[0020] In other embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 200; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 212. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 200; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 213. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 200; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 214. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 200; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 215. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 200; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 216. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 202; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 217. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 202; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 218. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 143; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 219. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 143; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 220. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 143; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 221. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 143; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 142. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 143; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 204. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 143; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 222.In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 200; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 223. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 200; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 207. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 208; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 117. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 209; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 110. In some embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence of SEQ ID NO: 210; and (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 148.

[0021] In certain embodiments, the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 143, 200, 202, 208, 209 and 210; and (b) a heavy chain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 142, 204, 222, 223, 207, 117, 110, 148, 119, 98, 120, 112, 205, 106, 118 and 111.

[0022] In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 67-98 within the amino acid sequence of SEQ ID NO: 146. In certain embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 67-74 within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 93-98 within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 30-93 within the amino acid sequence of SEQ ID NO: 146.

[0023] In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one residue within the amino acid sequence of SEQ ID NO: 146, the residue selected from the group consisting of L30, I36, Q52, T67, R69, F74, K93, R95, K96, and S98. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to L30 within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to I36 within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to Q52 within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to T67 within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to R69 within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to F74 within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to K93 within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to R95 within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to K96 within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to S98 within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to T67, R69, R95, K96, and S98 within the amino acid sequence of SEQ ID NO: 146.

[0024] In certain embodiments, the antibody or antigen-binding fragment thereof reduces binding between SIRPα and CD47. In some embodiments, the antibody or antigen-binding fragment thereof reduces binding between SIRPα and CD47, wherein the IgV domain of SIRPα comprises a haplotype, and the IgV domain comprising the haplotype is selected from the group consisting of SEQ ID NO: 149, 150, 151, 152, 153, and 154. In some embodiments, the antibody or antigen-binding fragment thereof reduces binding of CD47 to each of the six SIRPα haplotypes, wherein the six SIRPα haplotypes consist of SIRPαv1, SIRPαv2, SIRPαv3, SIRPαv4, SIRPαv5, and SIRPαv6, and wherein the IgV domain of SIRPαv1 comprises SEQ ID NO: 149, the IgV domain of SIRPαv2 comprises SEQ ID NO: 150, the IgV domain of SIRPαv3 comprises SEQ ID NO: 151, the IgV domain of SIRPαv4 comprises SEQ ID NO: 152, the IgV domain of SIRPαv5 comprises SEQ ID NO: 153, and the IgV domain of SIRPαv6 comprises SEQ ID NO: 154.

[0025] In some embodiments, the antibody or antigen-binding fragment thereof reduces binding between SIRPα and CD47, wherein CD47-SIRPα binding is reduced by 50%, 60%, 70%, 80%, 90%, 95%, or 99%.

[0026] In certain embodiments, the antibody or antigen-binding fragment thereof reduces the binding between SIRPα and CD47, wherein the EC of the antibody or antigen-binding fragment thereof for reducing CD47-SIRPα binding is 50 In other embodiments, the antibody or antigen-binding fragment thereof reduces the binding between SIRPα and CD47, wherein the EC of the antibody or antigen-binding fragment thereof for reducing CD47-SIRPα binding is about 1 pM to about 10 pM, about 10 pM to about 100 pM, about 100 pM to about 1 nM, about 1 nM to about 10 nM, or about 10 nM to about 100 nM. 50about 2 nM, about 2.1 nM, about 2.2 nM, about 2.3 nM, about 2.4 nM, about 2.5 nM, about 2.6 nM, about 2.7 nM, about 2.8 nM, about 2.9 nM, about 3 nM, about 3.1 nM, about 3.2 nM, about 3.3 nM, about 3.4 nM, about 3.5 nM, about 3.6 nM, about 3.7 nM, about 3.8 nM, about 3.9 nM, about 4.0 nM, about 5.1 nM, about 5.2 nM, about 5.3 nM, about 5.4 nM, about 5.6 nM, about 5.7 nM, about 5.8 nM, about 5.9 nM, about 6.0 nM, about 6.1 nM, about 6.2 nM, about 6.3 nM, about 6.4 nM, about 6.5 nM, about 6.6 nM, about 6.7 nM, about 6.8 nM, about 6.9 nM, about 7. M, about 4.1 nM, about 4.2 nM, about 4.3 nM, about 4.4 nM, about 4.5 nM, about 4.6 nM, about 4.7 nM, about 4.8 nM, about 4.9 nM, about 5.0 nM, about 5.1 nM, about 5.2 nM, about 5.3 nM, about 5.4 nM, about 5.5 nM, about 5.6 nM, about 5.7 nM, about 5.8 nM, about 5.9 nM or about 6.0 nM.

[0027] In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about 100% or about or at least 95%, 90%, 85%, 80% or 75% SIRPα receptor occupancy within about 24 hours after administration to the patient. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about or at least 95% SIRPα receptor occupancy within about 6, 12, 24, 36, 48, 60 or 72 hours after administration to the patient. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about or at least 90% SIRPα receptor occupancy within about 6, 12, 24, 36, 48, 60 or 72 hours after administration to the patient. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about or at least 85% SIRPα receptor occupancy within about 6, 12, 24, 36, 48, 60 or 72 hours after administration to the patient. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about or at least 80% SIRPα receptor occupancy within about 6, 12, 24, 36, 48, 60, or 72 hours after administration to the patient. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about or at least 75% SIRPα receptor occupancy within about 6, 12, 24, 36, 48, 60, or 72 hours after administration to the patient. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about 100% SIRPα receptor occupancy within about 24 hours after administration to the patient and maintain about 100% occupancy for about or at least 6, 12, 24, 36, 48, 60, 72, 84, or 96 hours or more. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about or at least 95% SIRPα receptor occupancy within about 24 hours after administration to the patient and maintain about or at least 95% occupancy for about or at least 6, 12, 24, 36, 48, 60, 72, 84, or 96 hours or more. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about or at least 90% SIRPα receptor occupancy within about 24 hours after administration to the patient and maintain about or at least 90% occupancy for about or at least 6, 12, 24, 36, 48, 60, 72, 84, or 96 hours or more. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about or at least 85% SIRPα receptor occupancy within about 24 hours after administration to the patient and maintain about or at least 85% occupancy for about or at least 6, 12, 24, 36, 48, 60, 72, 84, or 96 hours or more.In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about or at least 80% SIRPα receptor occupancy within about 24 hours after administration to a patient and maintain about or at least 80% occupancy for about or at least 6, 12, 24, 36, 48, 60, 72, 84, or 96 hours or more. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about 100%, about or at least 95%, about or at least 90%, about or at least 85%, or about or at least 80% SIRPα receptor occupancy within about 24 hours after administration to a patient and maintain about or at least 80% occupancy for about or at least 6, 12, 24, 36, 48, 60, 72, 84, or 96 hours or more. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about 100%, about or at least 95%, about or at least 90%, about or at least 85%, or about or at least 80% SIRPα receptor occupancy within about 24 hours after administration to a patient and maintain about or at least 95%, about or at least 90%, about or at least 85%, or about or at least 80% occupancy for about or at least 6, 12, 24, 36, 48, 60, 72, 84, or 96 hours. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about 100%, about or at least 95%, about or at least 90%, about or at least 85%, or about or at least 80% SIRPα receptor occupancy within about 24 hours after administration to a patient and maintain about or at least 95%, about or at least 90%, about or at least 85%, or about or at least 80% occupancy for about or at least 24 hours. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about 100%, about or at least 95%, about or at least 90%, about or at least 85%, or about or at least 80% SIRPα receptor occupancy within about 24 hours after administration to the patient and maintain about or at least 80% occupancy for another 24 hours. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about 100% SIRPα receptor occupancy within about 24 hours after administration to the patient and maintain about 80% occupancy for about or at least 24 hours or more. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about or at least 95% SIRPα receptor occupancy within about 24 hours after administration to the patient and maintain about or at least 80% occupancy for about or at least 24 hours or more. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about or at least 90% SIRPα receptor occupancy within about 24 hours after administration to a patient and maintain about or at least 80% occupancy for about or at least 24 hours more.In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about or at least 85% SIRPα receptor occupancy within about 24 hours after administration to a patient and maintain about or at least 80% occupancy for about or at least 24 hours. In some embodiments, the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein achieve about or at least 80% SIRPα receptor occupancy within about 24 hours after administration to a patient and maintain about or at least 80% occupancy for about or at least 24 hours. In some embodiments, the receptor occupancy provided in this paragraph can be as provided in this paragraph with a single dose of 0.1 mg / kg, 0.2 mg / kg, 0.3 mg / kg, 0.4 mg / kg, 0.5 mg / kg, 0.6 mg / kg, 0.7 mg / kg, 0.8 mg / kg, 0.9 mg / kg, 1.0 mg / kg, 1.1 mg / kg, 1.2 mg / kg, 1.3 mg / kg, 1.4 mg / kg, 1.5 mg /

[0145] In some embodiments, the present invention provides an anti-SIRPα antibody or antigen-binding fragment thereof provided herein at a dose of 1.6 mg / kg, 1.7 mg / kg, 1.8 mg / kg, 1.9 mg / kg, 2.0 mg / kg, 2.1 mg / kg, 2.2 mg / kg, 2.3 mg / kg, 2.4 mg / kg, 2.5 mg / kg, 2.6 mg / kg, 2.7 mg / kg, 2.8 mg / kg, 2.9 mg / kg or 3.0 mg / kg of the anti-SIRPα antibody or antigen-binding fragment thereof provided herein.In some embodiments, the receptor occupancies provided in this paragraph can be as provided in this paragraph with a single dose of 25 mg, 30 mg, 40 mg, 50 mg, 60 mg, 70 mg, 80 mg, 90 mg, 100 mg, 150 mg, 200 mg, 250 mg, 300 mg, 350 mg, 400 mg, 450 mg, 500 mg, 550 mg, 600 mg, 650 mg, 700 mg, 750 mg, 800 mg, 850 mg, 900 mg, 950 mg, 1000 mg, 1050 mg, 1100 mg, 1150 mg, 1200 mg, 1250 mg, 1300 mg, 1350 mg, 1400 mg, 1450 mg. 0 mg, 1500 mg, 1550 mg, 1600 mg, 1650 mg, 1700 mg, 1750 mg, 1800 mg, 1850 mg, 1900 mg, 1950 mg, 2000 mg, 2100 mg, 2200 mg, 2300 mg, 2400 mg, 2500 mg, 2600 mg, 2700 mg, 2800 mg, 2900 mg, 3000 mg, 3100 mg, 3200 mg, 3300 mg, 3400 mg, 3500 mg, 3600 mg, 3700 mg, 3800 mg, 3900 mg or 4000 mg of the anti-SIRPα antibodies or antigen-binding fragments thereof provided herein.

[0028] In another embodiment, the antibody or its antigen-binding fragment specifically binds to one or more of the six SIRPα haplotypes, wherein the six SIRPα haplotypes are composed of SIRPαv1, SIRPαv2, SIRPαv3, SIRPαv4, SIRPαv5, and SIRPαv6, and wherein the IgV domain of SIRPαv1 comprises SEQ ID NO: 149, the IgV domain of SIRPαv2 comprises SEQ ID NO: 150, the IgV domain of SIRPαv3 comprises SEQ ID NO: 151, the IgV domain of SIRPαv4 comprises SEQID NO: 152, the IgV domain of SIRPαv5 comprises SEQ ID NO: 153, and the IgV domain of SIRPαv6 comprises SEQ ID NO: 154. In some embodiments, the antibody or its antigen-binding fragment binds to each of the six SIRPα haplotypes. In other embodiments, the antibody or its antigen-binding fragment binds to each of the six SIRPα haplotypes with a dissociation constant (K) of no more than 5 nM. D ) binds to each of these six SIRPα haplotypes.

[0029] In certain embodiments, the antibody or antigen-binding fragment thereof has a K of no greater than 0.2 nM. DIn some embodiments, the antibody or antigen-binding fragment thereof binds to purified SIRPαv1 with a dissociation constant (K) of about 0.13 nM. D ) binds to purified SIRPαv1. In certain embodiments, the antibody or antigen-binding fragment thereof binds to purified SIRPαv1 with a K of no greater than 5 nM. D Binds to purified SIRPαv2. In some embodiments, the antibody or antigen-binding fragment thereof binds to purified SIRPαv2 with a K of about 4.4 nM. D Binds to purified SIRPαv2. In certain embodiments, the antibody or antigen-binding fragment thereof binds to purified SIRPαv2 with a K of no greater than 0.2 nM. D Binds to purified SIRPαv3. In some embodiments, the antibody or antigen-binding fragment thereof binds to purified SIRPαv3 with a K of about 0.15 nM. D Binds to purified SIRPαv3. In certain embodiments, the antibody or antigen-binding fragment thereof binds to purified SIRPαv3 with a K of no greater than 2 nM. D Binds to purified SIRPαv4. In some embodiments, the antibody or antigen-binding fragment thereof binds to purified SIRPαv4 with a K of about 1.5 nM. D Binds to purified SIRPαv4. In certain embodiments, the antibody or antigen-binding fragment thereof binds to purified SIRPαv4 with a K of no greater than 0.7 nM. D Binds to purified SIRPαv5. In some embodiments, the antibody or antigen-binding fragment thereof binds to purified SIRPαv5 with a K of about 0.6 nM. D Binds to purified SIRPαv5. In certain embodiments, the antibody or antigen-binding fragment thereof binds to purified SIRPαv5 with a K of no greater than 0.2 nM. D Binds to purified SIRPαv6. In some embodiments, the antibody or antigen-binding fragment thereof binds to purified SIRPαv6 with a K of about 0.18 nM. D Binds to purified SIRPαv6.

[0030] In other embodiments, the antibody or antigen-binding fragment thereof has an EC of about 1 pM to about 10 pM, about 10 pM to about 100 pM, about 100 pM to about 1 nM, about 1 nM to about 10 nM, or about 10 nM to about 100 nM. 50 Binds to human SIRPα expressed on cells. In certain embodiments, the antibody or antigen-binding fragment thereof is expressed as follows: 50Binds to human SIRPα expressed on cells: about 2 nM, about 2.1 nM, about 2.2 nM, about 2.3 nM, about 2.4 nM, about 2.5 nM, about 2.6 nM, about 2.7 nM, about 2.8 nM, about 2.9 nM, about 3 nM, about 3.1 nM, about 3.2 nM, about 3.3 nM, about 3.4 nM, about 3.5 nM, about 3.6 nM, about 3.7 nM, about 3.8 nM, about 3.9 nM, about 4.0 nM, about 4.1 nM, about 4.2 nM, about 4.3 nM, about 4.4 nM, about 4.5 nM, about 4.6 nM, about 4.7 nM, about 4.8 nM, about 4.9 nM, about 5.0 nM, about 5.1 nM, about 5.2 nM, about 5.3 nM, about 5.4 nM, about 5.5 nM, about 5.6 nM, about 5.7 nM, about 5.8 nM, about 5.9 nM, or about 6.0 nM.

[0031] In some embodiments, the antibody or antigen-binding fragment thereof specifically binds to human SIRPα and / or monkey SIRPα, but not to rodent SIRPα. In certain embodiments, the antibody or antigen-binding fragment thereof is expressed as follows: 50 Binds to cynomolgus monkey (cyno) SIRPα expressed on cells: about 1 pM to about 10 pM, about 10 pM to about 100 pM, about 100 pM to about 1 nM, about 1 nM to about 10 nM, or about 10 nM to about 100 nM. In some embodiments, the antibody or antigen-binding fragment thereof is expressed at the following EC 50 Binds to cynomolgus monkey SIRPα expressed on cells: about 2 nM, about 2.1 nM, about 2.2 nM, about 2.3 nM, about 2.4 nM, about 2.5 nM, about 2.6 nM, about 2.7 nM, about 2.8 nM, about 2.9 nM, about 3 nM, about 3.1 nM, about 3.2 nM, about 3.3 nM, about 3.4 nM, about 3.5 nM, about 3.6 nM, about 3.7 nM, about 3.8 nM, about 3.9 nM. 9 nM, about 4.0 nM, about 4.1 nM, about 4.2 nM, about 4.3 nM, about 4.4 nM, about 4.5 nM, about 4.6 nM, about 4.7 nM, about 4.8 nM, about 4.9 nM, about 5.0 nM, about 5.1 nM, about 5.2 nM, about 5.3 nM, about 5.4 nM, about 5.5 nM, about 5.6 nM, about 5.7 nM, about 5.8 nM, about 5.9 nM or about 6.0 nM.

[0032] In some embodiments, the antibody or antigen-binding fragment thereof enhances phagocytosis of cancer cells by co-cultured macrophages compared to phagocytosis by untreated macrophages or macrophages treated with a control isotype antibody. In some embodiments, the antibody or antigen-binding fragment thereof enhances phagocytosis of cancer cells by co-cultured macrophages compared to phagocytosis by untreated macrophages or macrophages treated with a control isotype antibody, wherein the antibody or antigen-binding fragment thereof is used as a monotherapeutic agent.

[0033] In certain embodiments, the antibody or its antigen-binding fragment enhances the phagocytosis of cancer cells by co-cultured macrophages compared to the phagocytosis of untreated macrophages or macrophages treated with a control isotype antibody, wherein the antibody or its antigen-binding fragment is used in combination with a second therapeutic agent. In some embodiments, the second therapeutic agent is cetuximab or rituximab. In one embodiment, the second therapeutic agent is cetuximab. In another embodiment, the second therapeutic agent is rituximab.

[0034] In certain embodiments, the antibody or antigen-binding fragment thereof enhances phagocytosis of cancer cells by co-cultured macrophages, compared to phagocytosis by untreated macrophages or macrophages treated with a control isotype antibody, wherein SIRPα is expressed on the macrophages, the cancer cells, or both the macrophages and the cancer cells. In some embodiments, the SIRPα on the macrophages and / or cancer cells is one or more of six SIRPα haplotypes, wherein the six SIRPα haplotypes consist of SIRPαv1, SIRPαv2, SIRPαv3, SIRPαv4, SIRPαv5, and SIRPαv6, and wherein the IgV domain of SIRPαv1 comprises SEQ ID NO: 149, the IgV domain of SIRPαv2 comprises SEQ ID NO: 150, the IgV domain of SIRPαv3 comprises SEQ ID NO: 151, the IgV domain of SIRPαv4 comprises SEQ ID NO: 152, the IgV domain of SIRPαv5 comprises SEQID NO: 153, and the IgV domain of SIRPαv6 comprises SEQ ID NO: 154.

[0035] In some embodiments, the antibody or antigen-binding fragment thereof increases the minimum percentage of phagocytic macrophages in a population of macrophages to about 10%, 20%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 99%. In other embodiments, the antibody or antigen-binding fragment thereof enhances phagocytosis of macrophages by about 10%, 20%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 125%, 150%, 175%, 200%, 250%, 300%, 400%, 500%, 600%, 700%, 800%, 900%, or 1000% compared to untreated macrophages or macrophages treated with a control isotype antibody.

[0036] In certain embodiments, the antibody or antigen-binding fragment thereof enhances phagocytosis of cancer cells by co-cultured macrophages compared to untreated macrophages or macrophages treated with a control isotype antibody, wherein the cancer cells are from colorectal cancer, head and neck squamous cell carcinoma, acute myeloid leukemia, or diffuse large B-cell lymphoma (DLBCL). In some embodiments, the antibody or antigen-binding fragment thereof enhances phagocytosis of cancer cells by co-cultured macrophages compared to untreated macrophages or macrophages treated with a control isotype antibody, wherein the cancer cells are from non-Hodgkin's lymphoma (NHL), such as DLBCL, follicular lymphoma, marginal zone lymphoma, and mantle cell lymphoma. In other embodiments, the antibody or antigen-binding fragment thereof enhances phagocytosis of cancer cells from Grade 1 follicular lymphoma, Grade 2 follicular lymphoma, Grade 3a follicular lymphoma, Grade 3b follicular lymphoma, relapsed follicular lymphoma (including, e.g., Grade 1, Grade 2, Grade 3a, and Grade 3b), refractory follicular lymphoma (including, e.g., Grade 1, Grade 2, Grade 3a, and Grade 3b), relapsed DLBCL, or refractory DLBCL by co-cultured macrophages compared to untreated macrophages or macrophages treated with a control isotype antibody.

[0037] In certain embodiments, the antibody or antigen-binding fragment thereof synergizes with a second therapeutic agent to enhance phagocytosis of cancer cells by co-cultured macrophages compared to untreated macrophages or macrophages treated with a control isotype antibody. In some embodiments, the second therapeutic agent is cetuximab or rituximab. In one embodiment, the second therapeutic agent is cetuximab. In another embodiment, the second therapeutic agent is rituximab.

[0038] In some embodiments, the antibody or antigen-binding fragment thereof and the second therapeutic agent synergize to enhance phagocytosis of cancer cells by co-cultured macrophages compared to phagocytosis by untreated macrophages or macrophages treated with a control isotype antibody, wherein SIRPα is expressed on the macrophages, the cancer cells, or both the macrophages and the cancer cells. In some embodiments, the SIRPα on the macrophages and / or cancer cells is one or more of six SIRPα haplotypes, wherein the six SIRPα haplotypes consist of SIRPαv1, SIRPαv2, SIRPαv3, SIRPαv4, SIRPαv5, and SIRPαv6, and wherein the IgV domain of SIRPαv1 comprises SEQ ID NO: 149, the IgV domain of SIRPαv2 comprises SEQ ID NO: 150, the IgV domain of SIRPαv3 comprises SEQ ID NO: 151, the IgV domain of SIRPαv4 comprises SEQ ID NO: 152, the IgV domain of SIRPαv5 comprises SEQ ID NO: 153, and the IgV domain of SIRPαv6 comprises SEQ ID NO: 154.

[0039] In certain embodiments, the difference between the percentage of phagocytic macrophages induced by the antibody or antigen-binding fragment and the second therapeutic agent in cooperation with each other and the sum of the percentages of phagocytosis induced by the antibody or antigen-binding fragment and the second therapeutic agent is about 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65% or 70%. In other embodiments, the antibody or antigen-binding fragment and the second therapeutic agent in cooperation with each other increase the percentage of phagocytic macrophages by about 10%, 20%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 125%, 150%, 175%, 200%, 250%, 300% or 400% relative to the sum of the percentages of phagocytosis induced by the antibody or antigen-binding fragment and the second therapeutic agent, respectively.

[0040] In some embodiments, the antibody or antigen-binding fragment synergistically enhances phagocytosis of cancer cells with a second therapeutic agent, wherein the cancer cells are from colorectal cancer, head and neck squamous cell carcinoma, acute myeloid leukemia or DLBCL. In some embodiments, the antibody or antigen-binding fragment synergistically enhances phagocytosis of cancer cells with a second therapeutic agent, wherein the cancer cells are from NHL, such as DLBCL, follicular lymphoma, marginal zone lymphoma and mantle cell lymphoma. In other embodiments, the antibody or antigen-binding fragment synergistically enhances phagocytosis of cancer cells with a second therapeutic agent, wherein the cancer cells are from grade 1 follicular lymphoma, grade 2 follicular lymphoma, grade 3a follicular lymphoma, grade 3b follicular lymphoma, relapsed follicular lymphoma (including, for example, grade 1, grade 2, grade 3a and grade 3b), refractory follicular lymphoma (including, for example, grade 1, grade 2, grade 3a and grade 3b), relapsed DLBCL or refractory DLBCL.

[0041] In some embodiments, the antibody or its antigen-binding fragment has ADCC activity that is weakened compared to an isotype control antibody, ADCP activity that is weakened compared to an isotype control antibody, and / or CDC activity that is weakened compared to an isotype control antibody. In some embodiments, the antibody or its antigen-binding fragment has ADCC activity that is weakened compared to an isotype control antibody. In certain embodiments, the maximum ADCC activity of the antibody or its antigen-binding fragment is no more than about 5%, 10%, 20%, 30% or 40% of the cytotoxicity as measured by the percentage of target cells killed. In some embodiments, the antibody or its antigen-binding fragment has ADCP activity that is weakened compared to an isotype control antibody. In other embodiments, the maximum ADCP activity of the antibody or its antigen-binding fragment is no more than about 5%, 10%, 20% or 30% of phagocytic macrophages targeting autologous T cells and / or monocytes. In some embodiments, the antibody or its antigen-binding fragment has CDC activity that is weakened compared to an isotype control antibody. In another embodiment, in a CDC assay, the EC of the antibody or its antigen-binding fragment is no more than about 5%, 10%, 20% or 30% of the phagocytic macrophages targeting autologous T cells and / or monocytes. 50 At least 100 μM.

[0042] In some embodiments, the antibody or antigen-binding fragment thereof induces cytokine release that does not exceed the level of cytokine release induced by an isotype control antibody.

[0043] In some embodiments, provided herein is an antibody. In other embodiments, provided herein is an antigen-binding fragment of an antibody.

[0044] In some embodiments, the antibody or its antigen-binding fragment is a monoclonal antibody. In certain embodiments, the antibody or its antigen-binding fragment is a humanized, human, or chimeric antibody. In some embodiments, the antibody or its antigen-binding fragment is a deimmunized antibody or a composite human antibody. In other embodiments, the antibody or its antigen-binding fragment is a Fab, Fab', F(ab')2, Fv, scFv, dsFv, a diabody, a triabody, a tetrabody, or a multispecific antibody formed from antibody fragments.

[0045] In certain embodiments, the antibody or antigen-binding fragment thereof is conjugated to an agent. In some embodiments, the agent conjugated to the antibody or antigen-binding fragment thereof is selected from the group consisting of: a radioisotope, a metal chelator, an enzyme, a fluorescent compound, a bioluminescent compound, and a chemiluminescent compound.

[0046] In another aspect, provided herein is a composition comprising an antibody or antigen-binding fragment thereof provided herein and a pharmaceutically acceptable carrier.

[0047] In one aspect, a polynucleotide is provided herein comprising a nucleic acid sequence encoding an antibody provided herein. In some embodiments, a polynucleotide is provided herein comprising a nucleic acid sequence encoding an antigen-binding fragment of an antibody provided herein.

[0048] In another aspect, provided herein is a polynucleotide comprising a nucleic acid sequence encoding an antibody or antigen-binding fragment thereof that binds to SIRPα, wherein the antibody or antigen-binding fragment thereof comprises: (a) the VL CDR1, VL CDR2 and VL CDR3 of any one of the antibodies SIRPAB-11, SIRPAB-12, SIRPAB-1, SIRPAB-2, SIRPAB-3, SIRPAB-4, SIRPAB-5, SIRPAB-6, SIRPAB-7, SIRPAB-8, SIRPAB-9, SIRPAB-10 or SIRPAB-13 as described in Table 1; and / or (b) VH CDR1, VH CDR2, and VH CDR3 of any one of antibodies SIRPAB-11, SIRPAB-12, SIRPAB-1, SIRPAB-2, SIRPAB-3, SIRPAB-4, SIRPAB-5, SIRPAB-6, SIRPAB-7, SIRPAB-8, SIRPAB-9, SIRPAB-10, SIRPAB-12, or SIRPAB-13 as described in Table 2. In some embodiments, provided herein is a polynucleotide comprising a nucleic acid sequence encoding an antibody or antigen-binding fragment thereof that binds to SIRPα, wherein the antibody or antigen-binding fragment thereof comprises: (a) a VL further comprising the VL FR1, VL FR2, VL FR3 and VL FR4 of any one of antibodies SIRPAB-11, SIRPAB-12, SIRPAB-1, SIRPAB-2, SIRPAB-3, SIRPAB-4, SIRPAB-5, SIRPAB-6, SIRPAB-7, SIRPAB-8, SIRPAB-9, SIRPAB-10 or SIRPAB-13 as described in Table 3. and / or (b) VH FR1, VH FR2, VH FR3, and VH FR4 of any one of antibodies SIRPAB-11, SIRPAB-12, SIRPAB-1, SIRPAB-2, SIRPAB-3, SIRPAB-4, SIRPAB-5, SIRPAB-6, SIRPAB-7, SIRPAB-8, SIRPAB-9, SIRPAB-10, or SIRPAB-13 as described in Table 4.

[0049] In another aspect, the present invention provides a polynucleotide comprising a nucleotide sequence encoding a VH, VL, or both a VH and a VL of an antibody or antigen-binding fragment thereof provided herein. In some embodiments, the polynucleotide comprises a nucleotide sequence encoding a heavy chain, a light chain, or both a heavy chain and a light chain of an antibody provided herein. In certain embodiments, the polynucleotide is operably linked to a promoter.

[0050] In some aspects, provided herein is a vector comprising a polynucleotide disclosed herein.

[0051] In other aspects, the present invention provides a cell comprising a polynucleotide disclosed herein. In another aspect, the present invention provides a cell comprising a vector disclosed herein. In other embodiments, the present invention provides an isolated cell that produces an antibody or antigen-binding fragment thereof provided herein.

[0052] In some aspects, the present disclosure also provides a kit comprising an antibody or antigen-binding fragment thereof provided herein.

[0053] In one aspect, the present invention provides a method for preparing an antibody or antigen-binding fragment thereof provided herein that specifically binds to a human SIRPα epitope, comprising culturing a cell provided herein to express the antibody or antigen-binding fragment thereof. In some embodiments, the method for preparing an antibody or antigen-binding fragment thereof comprises expressing a polynucleotide provided herein.

[0054] On the other hand, the present invention provides a method for enhancing the phagocytosis of macrophages, wherein the method comprises contacting macrophages with an effective amount of an antibody or antigen-binding fragment thereof provided herein, thereby enhancing the phagocytosis of macrophages compared to untreated macrophages or macrophages treated with a control isotype antibody. In certain embodiments of the method, the phagocytic activity of the macrophages is enhanced by about 10%, 20%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 125%, 150%, 175%, 200%, 250%, 300%, 400%, 500%, 600%, 700%, 800%, 900% or 1000%.

[0055] In other aspects, the present invention provides a method for increasing the percentage of phagocytic macrophages in a macrophage population, wherein the method comprises contacting the macrophages with an effective amount of an antibody or antigen-binding fragment thereof as described herein, thereby increasing the percentage of phagocytic macrophages in the macrophage population compared to untreated macrophages or macrophages treated with a control isotype antibody. In some embodiments of the method, the minimum percentage of phagocytic macrophages in the macrophage population is increased to about 10%, 20%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 99%.

[0056] On the one hand, the present invention provides a method for enhancing the phagocytosis of cancer cells by a macrophage population, wherein the method comprises contacting cancer cells, macrophages, or both cancer cells and macrophages with an effective amount of an antibody or antigen-binding fragment thereof provided herein, thereby enhancing the phagocytosis of cancer cells by the macrophage population compared to untreated macrophages or macrophages treated with a control isotype antibody. In certain embodiments of the method for enhancing the phagocytosis of cancer cells by a macrophage population, the minimum percentage of phagocytic macrophages in the macrophage population is increased to about 10%, 20%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 99%.

[0057] In some embodiments of the method, phagocytosis of the macrophages is measured by co-culturing macrophages labeled with a first fluorescent dye and cancer cells labeled with a second fluorescent dye, wherein the first fluorescent dye and the second fluorescent dye are different. In certain embodiments of the method, the percentage of phagocytic macrophages is measured by determining the percentage of macrophages that contain cancer cells.

[0058] In another aspect, provided herein is a method of enhancing phagocytosis of cancer cells in a subject, wherein the method comprises administering to the subject an effective amount of an antibody or antigen-binding fragment thereof provided herein, thereby enhancing phagocytosis of cancer cells in the subject compared to an untreated subject or a subject treated with an isotype control antibody.

[0059] In certain aspects, provided herein is a method of enhancing the elimination of cancer cells by phagocytosis in a subject, wherein the method comprises administering to the subject an effective amount of an antibody or antigen-binding fragment thereof provided herein.

[0060] In some aspects, the present disclosure also provides a method of targeting cancer cells in a subject for immune depletion, wherein the method comprises administering to the subject an effective amount of an antibody or antigen-binding fragment thereof provided herein.

[0061] In yet another aspect, the present disclosure also provides a method of treating cancer in a subject, wherein the method comprises administering to the subject an effective amount of the antibody or antigen-binding fragment thereof provided herein.

[0062] In some embodiments of the various methods provided herein, the cancer is selected from the group consisting of colorectal cancer, head and neck squamous cell carcinoma, acute myeloid leukemia, and DLBCL. In some embodiments of the various methods provided herein, the cancer is NHL, such as DLBCL, follicular lymphoma, marginal zone lymphoma, and mantle cell lymphoma. In certain embodiments of the various methods provided herein, the cancer is selected from the group consisting of: grade 1 follicular lymphoma, grade 2 follicular lymphoma, grade 3a follicular lymphoma, grade 3b follicular lymphoma, relapsed follicular lymphoma (including, for example, grade 1, grade 2, grade 3a, and grade 3b), refractory follicular lymphoma (including, for example, grade 1, grade 2, grade 3a, and grade 3b), relapsed DLBCL, or refractory DLBCL. In other embodiments of the methods, the cancer cells, macrophages, or both the cancer cells and macrophages in the methods express SIRPα.

[0063] In certain embodiments of the various methods provided herein, the cancer cells, macrophages, or both the cancer cells and macrophages express SIRPα, wherein the SIRPα is one or more of the six SIRPα haplotypes selected from the group consisting of SIRPαv1, SIRPαv2, SIRPαv3, SIRPαv4, SIRPαv5, and SIRPαv6. In certain embodiments, the IgV domain of SIRPαv1 comprises SEQ ID NO: 149. In some embodiments, the IgV domain of SIRPαv2 comprises SEQ ID NO: 150. In one embodiment, the IgV domain of SIRPαv3 comprises SEQ ID NO: 151. In other embodiments, the IgV domain of SIRPαv4 comprises SEQ ID NO: 152. In some embodiments, the IgV domain of SIRPαv5 comprises SEQ ID NO: 153. In other embodiments, the IgV domain of SIRPαv6 comprises SEQ ID NO: 154.

[0064] In other embodiments of the methods provided herein, the antibody or antigen-binding fragment thereof is co-administered with a second therapeutic agent. In some embodiments of the methods, the second therapeutic agent is cetuximab or rituximab. In one embodiment, the second therapeutic agent is cetuximab. In another embodiment, the second therapeutic agent is rituximab.

[0065] In certain embodiments of the methods provided herein, the subject is selected from the group consisting of: human, monkey, mouse, dog, and rat. In a specific embodiment, the subject is human. 3. Description of the Figures

[0066] Figure 1An overview of the anti-SIRPα antibody generation, screening, identification, and affinity maturation protocol is shown.

[0067] Figure 2 Identification of the most prevalent SIRPα polymorphisms around the CD47:SIRPα interface is shown. DLN = Most prevalent SIRPα polymorphism around the CD47:SIRPα interface. Red amino acid residues correspond to identified differences, covering approximately 95% of SIRPα polymorphisms at the CD47-SIRPα binding interface in the human population.

[0068] Figure 3 Binding of mouse CD11b-positive cells to several SIRPα antibodies is shown, demonstrating that antibodies SIRPAB-11 and SIRPAB-12 do not bind to mouse SIRPα; whereas SIRPAB-17 does bind to mouse SIRPα.

[0069] Figures 4A-4D SIRPAB-11 binds to Chinese hamster ovary-K1 cells overexpressing human and cynomolgus monkey SIRPα, but not to cells overexpressing rodent SIRPα, and SIRPAB-11 binds to EC 50 (A) SIRPAB-11-K322A binds to the EC of human SIRPα ectopically expressed in CHO cells. 50 (B) EC of SIRPAB-11-K322A binding to cynomolgus monkey SIRPα ectopically expressed in CHO cells 50 1.9 nM. (C) SIRPAB-11 does not bind to rat SIRPα-CHO-K1, as SIRPAB-11 binding to rat SIRPα-CHO-K1 is only at a level comparable to that of an isotype control IgG; whereas the positive control, anti-rat SIRPα antibody OX-41, exhibits robust binding in the same assay. (D) SIRPAB-11 does not bind to mouse SIRPα-CHO-K1, as SIRPAB-11 binding to mouse SIRPα-CHO-K1 is only at a level comparable to that of an isotype control IgG; whereas the positive control, anti-mouse SIRPα antibody P84, exhibits robust binding in the same assay. AF647 = Alexa Fluor 647 nm; CHO = Chinese hamster ovary; cyno = cynomolgus monkey; geometric MFI = geometric mean fluorescence intensity; K322A = immunoglobulin G1 with Lys322Ala.

[0070] Figures 5A-5FBinding of anti-SIRPα antibodies to SIRPα-expressing cells is shown. (A) Binding of human (left) and cynomolgus macaque (right) primary CD14-positive populations to SIRPAB-11-K322A (visualized by co-staining). (B) Binding profile of SIRPAB-11-K322A on human immune cell subsets in human peripheral blood mononuclear cells, shown as the level of binding of SIRPAB-11-K322A to various immune cells as indicated. AF647 = Alexa Fluor 647 nM; gMFI = geometric mean fluorescence intensity; ID = identifier; NK cells = natural killer cells; NKT cells = natural killer T cells. (C) Additional binding assays of primary human immune cell subsets to SIRPAB-11-K322A. (D) Binding assays of cynomolgus macaque primary immune cell subsets to SIRPAB-11-K322A. In (C) and (D), gMFI = geometric mean fluorescence intensity; mDC = myeloid dendritic cell; NK = natural killer; ns = not significant; PBMC = peripheral blood mononuclear cell. (E) Binding of SIRPAB-11-4PE antibody to two cynomolgus monkey donors and binding of SIRPAB-11-4PE to ECs of two cynomolgus monkey donors. 50 (F) Binding and affinity of SIRPAB-17, SIRPAB-19, SIRPAB-20, SIRPAB-21, and SIRPAB-18 to SIRPα-expressing cells. SIRPAB-19, SIRPAB-20, and SIRPAB-21 bind to mouse SIRPα with the highest affinity. Binding of an isotype antibody control was also used as a negative control.

[0071] Figures 6A-6B Anti-SIRPα antibodies block the binding between SIRPα and CD47. (A) SIRPAB-11-K322A blocks the EC interaction between the extracellular domain of CD47 and SIRPα 50 Values, as determined by Biacore. CD = cluster of differentiation; nM = nanomolar; RU = refractory unit. (B) Blocking activity of anti-mouse-SIRPα antibody against the binding of recombinant mouse CD47 to C57 / BL6 macrophages.

[0072] Figures 7A-7BThe crystal structure of SIRPAB-11-Fab bound to SIRPα domain 1 is shown. (A) Crystal structure of SIRPAB-11-Fab bound to SIRPα domain 1 and residues in SIRPα that interact with SIRPAB-11-Fab. HC = heavy chain; LC = light chain. The SIRPAB-11-Fab HC (colored blue) from SIRPAB-11-Fab mediates most of the interactions with SIRPα (colored magenta) (yellow dashed line) and shows the centrally located HC CDR3 (black arrow), which protrudes from the surface of the antigen-binding fragment and inserts into the SIRPα large pocket. Three key electrostatic interactions were observed and are indicated by black asterisks. Additional interactions were also observed between SIRPAB-11-Fab LC (colored gray) and SIRPα. (B) Comparison of SIRPAB-11-Fab and CD47 interaction sites on SIRPα. Fab = antigen-binding fragment; HC = heavy chain. The HC CDR3 of SIRPAB-11-Fab (blue bottom panel) occupies the same primary pocket on SIRPα (magenta and orange surfaces) that is recognized by the CD47 FG loop (yellow bottom panel). The LC of SIRPAB-11-Fab has been omitted for clarity.

[0073] Figure 8 Shown are cell growth and titer of SIRPAB-11-K322A produced in Expi Chinese Hamster Ovary cells.

[0074] Figures 9A-9KFigures show the antibody-dependent cellular cytotoxicity, complement-dependent activity, and antibody-dependent cellular phagocytosis activity of SIRPAB-11-K322A. (A) SIRPAB-11 does not induce antibody-dependent cellular cytotoxicity in the human MOLM-13 cell line expressing SIRPα. ADCC = antibody-dependent cellular cytotoxicity; G&P = G&P Biosciences; HuMy 9.6 = humanized monoclonal antibody 9.6; IgG1 = immunoglobulin G1; K322A = immunoglobulin G1 with Lys322Ala, MOLM-13 = acute myeloid leukemia cell line. (B) SIRPAB-11-K322A treatment does not induce antibody-dependent cellular cytotoxicity against autologous CD4-positive T cells in an unactivated state. (C) SIRPAB-11-K322A treatment does not induce antibody-dependent cellular cytotoxicity against autologous CD4-positive T cells in an activated state. (D) SIRPAB-11-K322A treatment does not induce antibody-dependent cellular toxicity against autologous CD8-positive T cells in an unactivated state. (E) SIRPAB-11-K322A treatment does not induce antibody-dependent cellular toxicity against autologous CD8-positive T cells in an activated state. (F) and (G) SIRPAB-11-K322A treatment does not induce antibody-dependent cellular toxicity against autologous monocytes, as measured by flow cytometry (F) and Mirrorball fluorescence cytometry (G). In (B) to (G), Ab = antibody; ADCC = antibody-dependent cellular toxicity; CD = cluster of differentiation; Fc = ligand segment; IgG = immunoglobulin; K322A = immunoglobulin G1 with Lys322Ala; Max = maximum value; NK = natural killer cells. (H) and (I) Lack of complement-dependent activity mediated by SIRPAB-11 ligand segment variants in the presence of rabbit complement serum. IgG1 = immunoglobulin G1; 4PE = immunoglobulin G4 with Ser228Pro and Leu235Glu mutations; mAb = monoclonal antibody; RLU = relative light units; SIRPα = signal regulatory protein alpha. (J) Macrophage phagocytosis of autologous T cells from donor 224. (K) Macrophage phagocytosis of autologous T cells from donor 224. In (J) and (K), CD = cluster of differentiation; IgG1 = immunoglobulin G1; K322A = immunoglobulin G1 with Lys322Ala; 4PE = immunoglobulin G4 with Ser228Pro and Leu235Glu mutations; SIRPα = signal regulatory protein alpha.

[0075] Figures 10A-10BAnalysis of antibody immunogenicity is shown. (A) EpiMatrix Antibody Immunogenicity Scale: Observed ADA responses for known antibodies and predicted ADA responses for the proposed VH / VL pair in SIRPAB-11-K322A and a SIRPα reference antibody with a light chain having the amino acid sequence of SEQ ID NO: 224 and a heavy chain having the amino acid sequence of SEQ ID NO: 225. All predictions were adjusted for the presence of tregitopes. (B) Antibody Immunogenicity Prediction SIRPAB-11-K322A.

[0076] Figures 11A-11J Figure 2 shows the cytokine release profile of human immune cells treated with SIRPAB-11. (A) to (I): Sample cytokine release assay data for cells treated with SIRPAB-11-K322A, including interleukin-1β (A), interleukin-6 (B), tumor necrosis factor alpha (TNFα) (C), interleukin-12p70 (D), granulocyte macrophage colony-stimulating factor (GM-CSF) (E), interleukin-2 (F), interferon-γ (IFN-γ) (G), interleukin-10 (H), and interleukin-8 (I). In (A) to (I), IgG1 = immunoglobulin G1; IL = interleukin; PBMC = peripheral blood mononuclear cells. (J) Summary of cytokine release data and associated statistical analysis for cells treated with SIRPAB-11-K322A.

[0077] Figures 12A-12H Shown are profiles of cytokine release from SIRPAB-11-treated PBMCs in the presence or absence of additional stimulation. (A) and (B) SIRPAB-11-K322A does not induce interleukin-1β in peripheral blood mononuclear cells in the presence (B) or absence (A) of lipopolysaccharide stimulation. In (A) and (B), IgG1 = immunoglobulin G1; IL-1β = interleukin 1β; LPS = lipopolysaccharide; K322A = immunoglobulin G1 with Lys322Ala. (C) Detailed results from (A) and (B). (D), (E), and (F): SIRPAB-11-K322A treatment does not alter interferon gamma levels in peripheral blood mononuclear cells in the presence (E) or absence (F) of 1 ng / ml Staphylococcal enterotoxin b stimulation or (D) in the absence of staphylococcal enterotoxin b stimulation. In (D), (E) and (F), IgG1 = immunoglobulin G1; IFN-γ = interferon gamma; K322A = immunoglobulin G1 with Lys322Ala; SEB = Staphylococcal enterotoxin B. (G) and (H): Detailed results from (E) and (F), respectively.

[0078] Figures 13A-13IFigure 1 shows the activity of SIRPAB-11 alone or in combination with a secondary antibody to enhance tumor phagocytosis. (A) to (C): Surface levels of SIRPα (A), CD47 (B), and EGFR (C) in four cetuximab-resistant KRAS mutant colorectal cancer cell lines stained with SIRPAB-11-IgG4PE, anti-CD47, and anti-EGFR. (D) to (F): Evaluation of tumor phagocytosis mediated by SIRPAB-11-K322A alone or in combination with cetuximab against four KRAS mutant colorectal cancer cell lines, including GP5d (D), GP2d (E), and SW480 (F). In (D) to (F), CD = cluster of differentiation; IgG1 = immunoglobulin G1; K322A = immunoglobulin G1 with a lysine to alanine mutation at position 322. (G) and (H): Effect of cetuximab concentration on phagocytosis of KRAS mutant colorectal cancer cell lines GP2d (G) and GP5d (H). (I) Evaluation of phagocytosis of FaDu head and neck squamous cell carcinoma cells mediated by SIRPAB-11-K322A in combination with cetuximab. CD = cluster of differentiation; FaDu = head and neck squamous cell carcinoma cell line; IgG1 = immunoglobulin G1.

[0079] Figure 14 Evaluation of DLBCL cell phagocytosis mediated by SIRPAB-11-K322A in combination with rituximab or SIRPAB-11-4PE in combination with rituximab is shown. IgG1 = immunoglobulin G1; K322A = immunoglobulin G1 with Lys322Ala; OCI-LY3 = DLBCL cell line.

[0080] Figures 15A-15FThe effects of SIRPAB-11Fc variants as single agents on phagocytosis of human cells and the effects of SIRPAB-11Fc variants on phagocytosis of mouse or cynomolgus macaque macrophages are shown. (A) The effect of SIRPAB-11-K322A and SIRPAB-11-IgG4PE as single agents to promote the phagocytic activity of the acute myeloid leukemia cell line MOLM-13. (B) The effect of SIRPAB-11-K322A and SIRPAB-11-IgG4PE as single agents to promote the phagocytic activity of the acute myeloid leukemia cell line OCI-AML2. (C) The effect of SIRPAB-11-K322A and SIRPAB-11-IgG4PE as single agents to promote the phagocytic activity of the acute myeloid leukemia cell line MV-4-11. (D) The effect of SIRPAB-11-K322A and SIRPAB-11-IgG4PE as single agents to promote the phagocytic activity of the acute myeloid leukemia patient-derived xenograft P1202. (E) Effects of SIRPAB-11-K322A and SIRPAB-11-IgG4PE as single agents on phagocytic activity targeting the acute myeloid leukemia patient-derived xenograft P5478. In (A) to (E), CD = cluster of differentiation; IgG = immunoglobulin G1; K322A = immunoglobulin G1 with Lys322Ala; 4PE = immunoglobulin G4 with Ser228Pro and Leu235Glu mutations; OCI-AML2 = acute myeloid leukemia (AML) cell line. (F) Effects of SIRPAB-11-K322A as single agent on phagocytic activity targeting the acute myeloid leukemia cell line OCI-AML2 by cynomolgus macaque macrophages. CD = cluster of differentiation; Hr = hours; IgG = immunoglobulin G1; K322A = immunoglobulin G1 with Lys322Ala; NS = not significant.

[0081] Figures 16A-16C Shown are (A) SIRPα, (B) CD20, and (C) CD47 surface expression on OCI-LY3, RIVA, Karpas 422, and Pfeiffer cells. Figures 16A-16C In, AF647=Alexa Fluor 647; GeoMFI=geometric mean fluorescence intensity; IgG1=immunoglobulin G1; and RSV=respiratory syncytial virus.

[0082] Figures 17A-17CAdditional studies of SIRPAB-11-K322A in combination with rituximab mediated phagocytosis of three DLBCL cells are shown. The effect of SIRPAB-11-K322A as a single agent or in combination with rituximab on promoting phagocytic activity targeting (A) OCI-LY3 cells, (B) RIVA cells, and (C) Karpas 422 cells is depicted. IgG1 K322A = immunoglobulin G1 with Lys322Ala; nM = nanomolar; RSV = respiratory syncytial virus.

[0083] Figures 18A-18D Additional studies of SIRPAB-11-K322A in combination with rituximab mediate phagocytosis of Pfeiffer cells. Depicted is the effect of SIRPAB-11-K322A as a single agent or in combination with rituximab in promoting phagocytic activity of Pfeiffer cells targeted by macrophages from (A) Donor 1, (B) Donor 2, (C) Donor 3, and (D) Donor 4. IgG1 K322A = immunoglobulin G1 with Lys322Ala; nM = nanomolar; RSV = respiratory syncytial virus.

[0084] Figures 19A-19B Design and validation of the SIRPα receptor occupancy assay are shown. (A) Schematic illustration of the SIRPα receptor occupancy assay, as described in Section 5.13. (B) FACS dot plots of the validation of the assay are shown, wherein the upper left panel shows SIRPAB-11-K322A staining, the upper right panel shows anti-SIRPα-29 staining, the lower left panel shows an exemplary dot plot without receptor occupancy, and the lower right panel shows an exemplary dot plot of full receptor occupancy. 4. Specific Implementation Methods

[0085] Provided herein are binding proteins, such as antibodies that bind to SIRPα (including human and / or cynomolgus monkey SIRPα). In some embodiments, the binding proteins provided herein are antibodies that bind to human and / or cynomolgus monkey (cyno) SIRPα but not to rodent SIRPα. In certain embodiments, SIRPα binding proteins, including antibodies disclosed herein, are antagonists (e.g., can block SIRPα ligand binding and block ligand-induced SIRPα signaling). In some embodiments, the binding proteins provided herein, such as antibodies to SIRPα, (i) bind to human and / or cynomolgus monkey SIRPα, (ii) compete with SIRPα ligands (e.g., CD47) for binding, and / or (iii) block SIRPα signaling. In one embodiment, the SIRPα antibody binds to human SIRPα. In one embodiment, the SIRPα antibody binds to cynomolgus monkey SIRPα. In one embodiment, the SIRPα antibody binds to human SIRPα and cynomolgus monkey SIRPα. In some embodiments, the SIRPα antibody competes with CD47 for binding to SIRPα. In other embodiments, the SIRPα antibody blocks SIRPα signaling. In yet another embodiment, the SIRPα antibody blocks CD47-induced SIRPα signaling.

[0086] In some embodiments, the SIRPα antibodies provided herein bind to both human SIRPα and cynomolgus monkey SIRPα. In specific embodiments, the SIRPα antibodies provided herein bind to each of at least 6 SIRPα haplotypes, including SIRPαv1, SIRPαv2, SIRPαv3, SIRPαv4, SIRPαv5, and SIRPαv6. In other specific embodiments, the SIRPα antibodies provided herein bind to at least one of these 6 SIRPα haplotypes, including SIRPαv1, SIRPαv2, SIRPαv3, SIRPαv4, SIRPαv5, and SIRPαv6. In another specific embodiment, the SIRPα antibodies provided herein bind to a SIRPα haplotype in the IgV domain, and the SIRPα haplotype in the IgV domain covers not less than 95% of the human population SIRPα polymorphism. In some embodiments, binding, competition, and / or signal transduction are analyzed in vitro (e.g., in a cell-based assay). In other embodiments, binding, competition and / or signaling are analyzed ex vivo (e.g., in a macrophage phagocytosis assay). In other embodiments, binding, competition and / or signaling are analyzed using a sample from a subject (e.g., a human subject). In certain embodiments, the assay comprises (1) a human or cynomolgus macaque macrophage phagocytosis assay (see, e.g., Example 9); (2) a cell-based competitive binding assay (see, e.g., Example 2); (3) a surface plasmon resonance (SPR) competitive binding assay (see, e.g., Example 2). In certain embodiments, a binding protein as described herein (such as an anti-SIRPα antibody) blocks CD47 activity consistent with the natural biological function of CD47, including activity induced by CD47 binding to SIRPα. In some embodiments, the blocking activity of the anti-SIRPα antibody is exhibited in vitro. In other embodiments, the blocking activity of the anti-SIRPα antibody is exhibited ex vivo.

[0087] In some embodiments of the present disclosure, the levels of cytokines (e.g., IL-1β, IL-2, IL-6, IL-8, IL-10, IL-12p70, TNFα, interferon γ, and granulocyte macrophage colony stimulating factor) induced by anti-SIRPα antibodies are no greater than or similar to those of negative isotype antibody controls. In some specific embodiments, the levels of cytokines (e.g., IL-1β, IL-2, IL-6, IL-8, IL-10, IL-12p70, TNFα, interferon γ, and granulocyte macrophage colony stimulating factor) induced by anti-SIRPα antibodies provided herein are within 2, 3, 4, 5, 6, 7, 8, 9, or 10 times the levels of those cytokines induced by negative isotype antibody controls. In certain embodiments, the negative isotype control antibody is cetuximab.

[0088] In some embodiments, the binding proteins provided herein (such as antibodies that bind to SIRPα) enhance the phagocytosis of cancer cells by co-cultured macrophages and / or increase the percentage of phagocytic macrophages in a population of macrophages co-cultured with cancer cells. In other embodiments, the binding proteins provided herein (such as antibodies that bind to SIRPα) enhance the phagocytosis of cancer cells by macrophages in a subject and / or increase the percentage of phagocytic macrophages in a population of macrophages in a subject with cancer.

[0089] In certain embodiments, the binding proteins provided herein, such as antibodies bound to SIRPα, have the common feature of competing with each other for binding to SIRPα. This competitive inhibition can show that each antibody binds to the same region (e.g., the same epitope) of SIRPα, thereby confirming a similar effect. In certain embodiments, the anti-SIRPα antibodies provided herein include human anti-SIRPα antibodies, such as SIRPAB-1, SIRPAB-2, SIRPAB-3, SIRPAB-4, SIRPAB-5, SIRPAB-6, SIRPAB-7, SIRPAB-8, SIRPAB-9, SIRPAB-10, SIRPAB-11, SIRPAB-12 or SIRPAB-13, or those derived from or based on these antibodies. In other embodiments, the anti-SIRPα antibodies provided herein compete for binding with antibodies that are, are derived from, or are based on SIRPAB-1, SIRPAB-2, SIRPAB-3, SIRPAB-4, SIRPAB-5, SIRPAB-6, SIRPAB-7, SIRPAB-8, SIRPAB-9, SIRPAB-10, SIRPAB-11, SIRPAB-12, or SIRPAB-13. In some embodiments, the anti-SIRPα antibodies have CDR sequences as described in Tables 1-2. In certain embodiments, the anti-SIRPα antibodies bind to a specific domain or epitope of human SIRPα (e.g., residues 67-98, 67-74, 93-98, or 30-93 of SEQ ID NO: 146; see Example 3). In addition, such binding is substantially attributable to specific amino acid residues within the region (e.g., T67, R69, R95, K96, and S98; see Example 3) that comprise the epitope recognized by the anti-SIRPα antibodies described herein. Taken together, the results described herein indicate that the effects observed for anti-SIRPα antibodies derived from or based on SIRPAB-11 (including antibodies having one or more CDRs described in Tables 1-2) can be extrapolated to other anti-SIRPα antibodies described herein having the same or similar epitope specificity (e.g., the same or similar CDRs). For example, the activity of antibodies against exemplary humanized anti-SIRPα antibodies as shown in Examples 2, 3, 9, 10, 11, and 12 is representative of the activity and effects of the anti-SIRPα antibodies described herein.

[0090] In some embodiments of the present disclosure, binding proteins (such as anti-SIRPα antibodies) may comprise immunoglobulin variable regions comprising one or more CDRs as described in Tables 1-2. In such binding proteins (e.g., anti-SIRPα antibodies), the CDRs may be joined to one or more scaffold regions or framework regions (FRs) to orient the CDRs to achieve appropriate antigen binding properties of the CDRs. Such binding proteins (including anti-SIRPα antibodies as described herein) may block or inhibit CD47 binding to SIRPα and CD47-induced SIRPα signaling.

[0091] 4.1 General Technology

[0092] The techniques and procedures described or referred to herein include those well understood and / or commonly employed by those skilled in the art using conventional methods, such as the widely utilized methods described in Sambrook et al., Molecular Cloning:A Laboratory Manual (3rd edition, 2001); Current Protocols in Molecular Biology (Ausubel et al., 2003); Therapeutic Monoclonal Antibodies:From Bench to Clinic (Ed. An, 2009); Monoclonal Antibodies:Methods and Protocols (Albitar ed., 2010); and Antibody Engineering Volumes 1 and 2 (Kontermann and Dübel eds., 2nd ed., 2010).

[0093] 4.2 Terminology

[0094] Unless otherwise described, all technical and scientific terms used herein have the same meanings as commonly understood by those of ordinary skill in the art. For the purposes of interpreting this specification, the following terminology will apply and, whenever appropriate, terms used in the singular will also include the plural form and vice versa. All patents, applications, published applications, and other publications are incorporated by reference in their entirety. In the event of a conflict between any description of a listed term and any document incorporated herein by reference, the terminology set forth below shall prevail.

[0095] The terms "SIRPα", "SIRPα", "protein SIRPα", "SIRPα polypeptide", "SIRPA", "SIRP-A", "SIRP-α" or "SIRPalpha" (also known as BIT, MFR, MYD1, P84, PTPNS1, SHPS1, CD172a) refer to a polypeptide ("polypeptide" and "protein" are used interchangeably herein) that is a member of the immunoglobulin-like (Ig-like) family and, in humans, is encoded by the signal regulatory protein alpha gene on human chromosome 20p13. Unless otherwise indicated, examples of SIRPα encompass any such native polypeptide from any vertebrate source, including mammals, such as primates (e.g., humans and cynomolgus monkeys (cynos)), dogs, and rodents (e.g., mice and rats). In certain embodiments, the term includes "related SIRPα polypeptides", including SNP variants thereof. The term "SIRPα" also encompasses "full-length" unprocessed SIRPα as well as any form of SIRPα produced by processing in cells. In some embodiments, human SIRPα has the amino acid sequence EEELQVIQPDKSVLVAAGETATLRCTATSLIPVGPIQWFRGAGPGRELIYNQKEGHFPRVTTVSDLTKRNNMDFSIRIGNITPADAGTYYCVKFRKGSPDDVEFKSGAGTELSVRAKPSAPVVSGPAARATPQHTVSFTCESHGFSPRDITLKWFKNGNELSDFQTNVDPVGESVSYSIHSTAKVVLTREDVHSQVICEVAHVTLQGDPLRGTANLSETIRVPPTLEV TQQPVRAENQVNVTCQVRKFYPQRLQLTWLENGNVSRTETASTVTENKDGTYNWMSWLLVNVSAHRDDVKLTCQVEHDGQPAVSKSHDLKVSAHPKEQGSNTAAENTGSNERNIYIVVGVVCTLLVALLMAALYLVRIRQKKAQGSTSSTRLHEPEKNAREITQDTNDITYADLNLPKGKKPAPQAAEPNNHTEYASIQTSPQPASEDTLTYADLDMVHLNRTPKQPAPKPEPSFSEYASVQVPRK (SEQ ID NO: 146). In other embodiments, SIRPα has the amino acid sequence of SEQ ID NO: 145, which is SEQ ID NO: 146 with an exemplary signal peptide.NCBI Reference Sequences NP_001035111.1, NP_001035112.1, NP_001317657.1, NP_542970.1, XP_005260727.1, XP_024307604.1, XP_006723608.1, and XP_011527475.1, and UniProtKB: P78324 provide other exemplary amino acid sequences of SIRPα. GENBANK Accession No. 140885, NCBI Reference Sequences NM_001040022.1, NM_001040023.1, NM_001330728.1, NM_080792.2, XM_005260670.3, XM_024451836.1, XM_006723545.4, and XM_011529173.2 provide exemplary human SIRPα nucleic acid sequences. In some embodiments, the cynomolgus SIRPα comprises or has the sequence MEPAGPAPGRLGPLLCLLLTASCAWSGVLGEEELQVIQPEKSVSVAAGESATLNCTATSLIPVGPIQWFRGVGPGRELIYSQKEGHFPRVTPVSDPTKRNNMDFSIRISNITPADAGTYYCVKFRKGSPDVELKSGAGTELSVRAKPSAPVVSGPAVRATAEHTVSFTCESHGFSP RDITLKWFKNGNELSDFQTNVDPAGKSVSYSIRSTARVVLTRRDVHSQVICEVAHVTLQGDPLRGTANLSEAIRVPPFLEVTQQSMRADNQVNVTCQVTKFYPQRLQLTWLENGNVSRTEMASALPENKDGTYNWTSWLLVNVSAHRDDVKLTCQVEHDGQPAVNKSFSVKVSAHPKEQGSNTAAENTGTNERNIY(SEQ ID NO:115).In certain embodiments, the mouse SIRPα comprises or has the sequence MEPAGPAPGRLGPLLLCLLLLSASCFCTGATGKELKVTQPEKSVSVAAGDSTVLNCTLTSLLPVGPIRWYRGVGPSRLLIYSFAGEYVPRIRNVSDTTKRNNMDFSIRISNVTPADAGIYYCVKFQKGSSEPDTEIQSGGGTEVYVLAKPSPPEVSGPADRGIPDQKVNFTCKSHGFS PRNITLKWFKDGQELHPLETTVNPSGKNVSYNISSTVRVVLNSMDVNSKVICEVAHITLDRSPLRGIANLSNFIRVSPTVKVTQQSPTSMNQVNLTCRAE RFYPEDLQLIWLENGNVSRNDTPKNLTKNTDGTYNYTSLFLVNSSAHREDVVFTCQVKHDQQPAITRNHTVLGFAHSSDQGSMQTFPDNNATHNWN(SEQ ID NO:102). In other embodiments, the mouse SIRPα is a NOD / SCID mouse SIRPα comprising or having the sequence MEPAGPAPGRLGPLLLCLLLSASCFCTGATRTEVKVIQPEKSVSVAAGDSTVLNCTLTSLLPVGPIRWYRGVGQSRQLIYSFTTEHFPRVTNVSDATKRSNLDFSIRISNVTPEDAGTYYCVKFQRGSPDTEIQSGGGTEVYVLAKPSPPEVSGPADRGIPDQKVNFTCKSHGFSPRNITLKWFKDGQELHPLETTVNPSGKNVSYNISSTVRVVLNSMDVNSKVICEVAHITLDRSPLRGIANLSNFIRVSPTVKVTQQSPTSMNQVNLTCRAERFYPEDLQLIWLENGNVSRNDTPKNLTKNTDGTYNYTSLFLVNSSAHREDVVFTCQVKHDQQPAITRNHTVLGFAHSSDQGSMQTFPDNNATHNWN (SEQ IDNO:100).

[0096] Unless otherwise indicated, the term "IgV domain," also referred to as "Ig-like V-type domain," "V domain," "N-terminal IgSF domain," "SIRPα domain 1," or "N-terminal V domain," as used herein, when used in conjunction with SIRPα, refers to a polypeptide containing amino acid residues 1 to 107 of human SIRPα having SEQ ID NO: 146 (EEELQVIQPDKSVLVAAGETATLRCTATSLIPVGPIQWFRGAGPGRELIYNQKEGHFPRVTTVSDLTKRNNMDFSIRIGNITPADAGTYYCVKFRKGSPDDVEFKSG SEQ ID NO: 203) in a human polymorphism and having a V-type Ig fold, and its equivalents in other human SIRPα polymorphisms and other SIRPαs from any vertebrate source, including mammals, such as primates (e.g., humans and cynomolgus monkeys (cynos)), dogs, and rodents (e.g., mice and rats).

[0097] As used herein, the term "SIRPα variant" means a SIRPα protein that comprises one or more (such as about 1 to about 25, about 1 to about 20, about 1 to about 15, about 1 to about 10, or about 1 to about 5) amino acid sequence substitutions, deletions and / or additions compared to the native or unmodified sequence. For example, a SIRPα variant can be obtained by one or more (such as about 1 to about 25, about 1 to about 20, about 1 to about 15, about 1 to about 10, or about 1 to about 5) changes in the amino acid sequence of native SIRPα. SIRPα variants include naturally occurring SIRPα variants, including allelic variants (e.g., SNP variants); splice variants; fragments; and interspecies homologs that retain SIRPα activity. Therefore, SIRPα variants also encompass SIRPα encoded by the SIRPα gene, including one or more single nucleotide polymorphisms (SNPs) in humans or other species, and "SIRPα haplotypes." "SIRPα haplotype" refers to a SIRPα variant with SNPs that tend to be inherited together. Thus, a "SIRPα haplotype" is a type of SIRPα polymorphism and may include a combination of any set of single nucleotide polymorphisms (SNPs) found in the SIRPα gene, wherein the set of SNPs tend to be inherited together. As will be appreciated by those skilled in the art, the anti-SIRPα antibodies provided herein can bind to SIRPα variants, including SIRPα haplotypes. As further described below, the six SIRPα haplotypes in the IgV domain of SIRPα, including SIRPαv1, SIRPαv2, SIRPαv3, SIRPαv4, SIRPαv5, and SIRPαv6, account for 95% of the polymorphisms in the CD47 binding region of SIRPα in the human population. The six SIRPα haplotypes in the IgV domain, SIRPαv1, SIRPαv2, SIRPαv3, SIRPαv4, SIRPαv5, and SIRPαv6, comprise the amino acid sequences SEQ ID NOs: 149, 150, 151, 152, 153, and 154, respectively, as shown in Table 5.

[0098] Table 5: Haplotypes of the SIRPα IgV domain in the SIRPα / CD47 binding interface

[0099]

[0100]

[0101] "Related SIRPα polypeptides" include allelic variants (e.g., SNP variants) that can retain SIRPα activity; splice variants; fragments; derivatives; substitution, deletion, and insertion variants; fusion polypeptides; and interspecies homologs. As will be appreciated by those skilled in the art, the anti-SIRPα antibodies provided herein can bind to SIRPα polypeptides, SIRPα polypeptide fragments, SIRPα antigens, and / or SIRPα epitopes. An "epitope" can be a portion of a larger SIRPα antigen, which can be a portion of a larger SIRPα polypeptide fragment, which in turn can be a portion of a larger SIRPα polypeptide. SIRPα can exist in native or denatured form. The SIRPα polypeptides described herein can be isolated from a variety of sources, such as from human tissue types or from another source, or prepared by recombinant or synthetic methods. Orthologs of SIRPα polypeptides are also well known in the art.

[0102] Exemplary SIRPα extracellular domain sequences comprising one of the six SIRPα haplotypes (SIRPαv1, SIRPαv2, SIRPαv3, SIRPαv4, SIRPαv5, or SIRPαv6) are shown in Table 6 below.

[0103] Table 6: Exemplary SIRPα extracellular domain sequences comprising one of the six SIRPα haplotypes.

[0104]

[0105]

[0106] The term "SIRPAB-11-K322A" refers to a SIRPAB-11 variant having a K322A substitution in the IgG1 Fc region. In certain embodiments, the SIRPα-K322A variant has the heavy chain amino acid sequence of HC_SIRPα-K322A (SEQ ID NO: 119).

[0107] The term "SIRPAB-11-AAS" refers to a SIRPAB-11 variant having an IgG1 AAS Fc region. In certain embodiments, the anti-SIRPα antibody variant has the heavy chain amino acid sequence of HC_SIRPAB-11-IgG1-AAS (SEQ ID NO: 98).

[0108] The term "SIRPAB-11-4PE" refers to a SIRPAB-11 variant having the IgG4PE heavy chain amino acid sequence as HC_SIRPAB-11-IgG4PE (SEQ ID NO: 120).

[0109] The term "SIRPα ligand" refers to a molecule that binds to SIRPα (eg, in vivo or in vitro). Non-limiting examples of SIRPα ligands include naturally occurring ligands, such as CD47, and artificially produced ligands.

[0110] The term "CD47", also known as "integrin-associated protein", "IAP" or "cluster of differentiation 47", refers to a transmembrane protein belonging to the immunoglobulin superfamily, which in humans is encoded by the CD47 gene on human chromosome 3. Unless otherwise indicated, examples of CD47 encompass any such native polypeptide from any vertebrate source, including mammals, such as primates (e.g., humans and cynomolgus monkeys (cynos)), dogs, and rodents (e.g., mice and rats). In certain embodiments, the term includes all natural variants of CD47, including allelic variants (e.g., SNP variants); splice variants; fragments; and derivatives. The term "CD47" also encompasses "full-length" unprocessed CD47 as well as any form of CD47 that is processed in cells. In some embodiments, the extracellular domain of CD47 has the amino acid sequence MYRMQLLSCIALSLALVTNSQLLFNKTKSVEFTFCNDTVVIPCFVTNMEAQNTTEVYVKWKFKGRDIYTFDGALNKSTVPTDFSSAKIEVSQLLKGDASLKMDKSDAVSHTGNYTCEVTELTREGETIIELKYRVV (SEQ ID NO: 116). NCBI reference sequences NP_001768.1, NP_942088.1, XP_005247966.1, XP_005247965.1, and XP_016863025.1 and the Uniprot database UniProtKB-Q08722 provide additional exemplary amino acid sequences of CD47. GenBank TM Exemplary human CD47 nucleic acid sequences are provided by ID No. 961, NCBI Reference Sequences NM_001777.3, NM_198793.2, XM_005247909.2, XM_005247908.2, and XM_017007536.1.

[0111] As used herein, the term "antagonist" when used in conjunction with SIRPα or SIRPα function means a molecule that can inhibit, reduce, attenuate, reduce or otherwise completely block one or more biological activities or functions of SIRPα. SIRPα functional antagonists include molecules that can block, inhibit, attenuate or reduce SIRPα-mediated or SIRPα-dependent signaling in cells expressing SIRPα. SIRPα functional antagonists also include molecules that can block, inhibit, attenuate or reduce SIRPα signaling (including downstream signaling induced by the connection or engagement between SIRPα and CD47). In some instances, SIRPα antagonists further include molecules that can block, inhibit, attenuate or reduce SIRPα binding to natural SIRPα binding molecules. In other instances, SIRPα antagonists additionally include molecules that can block, inhibit or reduce SIRPα binding to SIRPα ligands (such as CD47). "Antagonists" of SIRPα are "antagonistic" to SIRPα or SIRPα function. In some embodiments, provided herein are antagonist anti-SIRPα antibodies or fragments thereof.

[0112] A "blocking" antibody, a "neutralizing" antibody, or an "antagonist" antibody, when used in conjunction with SIRPα or SIRPα function, refers to an antibody that binds to SIRPα and acts as an antagonist of SIRPα or SIRPα activity or function. For example, a blocking antibody or antagonist antibody can substantially or completely inhibit the biological activity of SIRPα or the binding of CD47 to SIRPα. In some embodiments, provided herein are anti-SIRPα blocking antibodies or fragments thereof.

[0113] The term "binding protein" refers to a protein that comprises a portion that binds to SIRPα (e.g., one or more binding regions, such as CDRs), including human and / or cynomolgus monkey SIRPα, and optionally a scaffold or framework portion (e.g., one or more scaffolds or framework regions) that allows the binding portion to adopt a conformation that facilitates binding of the binding protein to a SIRPα polypeptide, fragment, or epitope. Examples of such binding proteins include antibodies, such as human antibodies, humanized antibodies, chimeric antibodies, recombinant antibodies, single-chain antibodies, double-chain antibodies, three-chain antibodies, four-chain antibodies, Fab fragments, F(ab')2 fragments, IgD antibodies, IgE antibodies, IgM antibodies, IgG1 antibodies, IgG2 antibodies, IgG3 antibodies, or IgG4 antibodies, and fragments thereof. The binding protein may comprise, for example, an alternative protein scaffold or an artificial scaffold grafted with CDRs or CDR derivatives. Such scaffolds include, but are not limited to, scaffolds derived from antibodies comprising mutations introduced, for example, to stabilize the three-dimensional structure of the binding protein; and fully synthetic scaffolds comprising, for example, biocompatible polymers. See, for example, Korndorfer et al., 2003, Proteins: Structure, Function, and Bioinformatics 53(1):121-29; and Roque et al., 2004, Biotechnol. Prog. 20:639-54. In addition, peptide antibody mimetics ("PAMs") can be used, as well as scaffolds based on antibody mimics (using fibronectin components as scaffolds). In the context of the present disclosure, for example, when the dissociation constant (K D )≤10 -7 When the binding protein specifically binds or selectively binds to SIRPα, the binding protein is said to bind specifically or selectively to SIRPα. In some embodiments, the binding protein (eg, antibody) can be about 10 -7 M to about 10 -12 M's K D Specifically binds to SIRPα. In certain embodiments, when K D ≤10 -8 M or K D ≤10 -9 M, the binding protein (eg, antibody) can specifically bind to SIRPα with high affinity. In one embodiment, the binding protein (eg, antibody) can bind to 1×10 -9 M to 10×10 -9 M's K D Specific binding to purified human SIRPα, as by In another embodiment, the binding protein (e.g., antibody) can be measured at 0.1×10 -9 M to 1×10 -9 M's K D Specific binding to purified human SIRPα, such as by KinExATM (Sapidyne, Boise, ID). In yet another embodiment, the binding protein (e.g., antibody) is measured at 0.1×10 -9 M to 10×10 -9 M's K D Specifically binds to human SIRPα expressed on cells. In certain embodiments, the binding protein (eg, antibody) is expressed at 0.1×10 -9 M to 1×10 -9 M's K D Specifically binds to human SIRPα expressed on cells. In some embodiments, the binding protein (eg, antibody) is expressed at 1×10 -9 M to 10×10 -9 M's K D Specifically binds to human SIRPα expressed on cells. In certain embodiments, the binding protein (eg, antibody) is at about 0.1×10 -9 M, about 0.5×10 -9 M, about 1×10 -9 M, about 5×10 -9 M, about 10×10 -9 M or any range or interval thereof D Specifically bind to human SIRPα expressed on cells. In yet another embodiment, the binding protein (eg, antibody) can be 0.1×10 -9 M to 10×10 -9 M's K D Specifically binds to cynomolgus monkey SIRPα expressed on cells. In certain embodiments, the binding protein (eg, antibody) is expressed at 0.1×10 -9 M to 1×10 -9 M's K D Specifically binds to cynomolgus monkey SIRPα expressed on cells. In some embodiments, the binding protein (eg, antibody) is expressed at 1×10 -9 M to 10×10 -9 M's K D Specifically binds to cynomolgus monkey SIRPα expressed on cells. In certain embodiments, the binding protein (eg, antibody) is expressed at about 0.1×10 -9 M, about 0.5×10 -9 M, about 1×10 -9 M, about 5×10 -9 M, about 10×10 -9 M or any range or interval thereof D Specifically binds to cynomolgus monkey SIRPα expressed on cells.

[0114] The terms "antibody," "immunoglobulin," or "Ig" are used interchangeably herein and in the broadest sense to specifically encompass, for example, individual anti-SIRPα monoclonal antibodies (including agonists, antagonists, neutralizing antibodies, full-length or intact monoclonal antibodies), anti-SIRPα antibody compositions with multi-epitope or mono-epitope specificity, polyclonal or monovalent antibodies, multivalent antibodies, multispecific antibodies formed from at least two intact antibodies (e.g., bispecific antibodies, so long as they exhibit the desired biological activity), single-chain anti-SIRPα antibodies, and fragments of anti-SIRPα antibodies, as described below. Antibodies can be human, humanized, chimeric, and / or affinity matured, as well as antibodies from other species (e.g., mouse, rabbit, etc.). The term "antibody" is intended to include B-cell polypeptide products within the class of immunoglobulin polypeptides that are capable of binding to a specific molecular antigen and are composed of two pairs of identical polypeptide chains, wherein each pair has one heavy chain (about 50-70 kDa) and one light chain (about 25 kDa), each amino-terminal portion of each chain includes a variable region of about 100 to about 130 or more amino acids, and each carboxyl-terminal portion of each chain includes a constant region. See, for example, Antibody Engineering (Borrebaeck, ed., 2nd ed., 1995); and Kuby, Immunology (3rd ed., 1997). In certain embodiments, a specific molecular antigen can be bound by an antibody provided herein, including a SIRPα polypeptide, a SIRPα fragment, or a SIRPα epitope. Antibodies also include, but are not limited to, synthetic antibodies, recombinantly produced antibodies, camelized antibodies, intrabodies, anti-idiotypic (anti-Id) antibodies, and functional fragments of any of the above (e.g., antigen-binding fragments, such as SIRPα binding fragments), wherein the functional fragment refers to a portion of an antibody heavy or light chain polypeptide that retains some or all of the binding activity of the antibody from which the fragment is derived. Non-limiting examples of functional fragments (e.g., antigen-binding fragments, such as SIRPα binding fragments) include single-chain Fv (scFv) (e.g., including monospecific, bispecific, etc.), Fab fragments, F(ab') fragments, F(ab')2 fragments, F(ab')2 fragments, disulfide-linked Fv (dsFv), Fd fragments, Fv fragments, diabodies, triabodies, tetrabodies, and minibodies. Specifically, the antibodies provided herein include immunoglobulin molecules and immunologically active portions of immunoglobulin molecules, such as antigen-binding domains or molecules that contain an antigen-binding site that binds to a SIRPα antigen (e.g., one or more CDRs of an anti-SIRPα antibody).Such antibody fragments can be found in, for example, Harlow and Lane, Antibodies: A Laboratory Manual (1989); Mol. Biology and Biotechnology: A Comprehensive Desk Reference (Myers ed., 1995); Huston et al., 1993, Cell Biophysics 22: 189-224; Plückthun and Skerra, 1989, Meth. Enzymol. 178: 497-515; and Day, Advanced Immunochemistry (2nd ed., 1990). The antibodies provided herein can belong to any class (e.g., IgG, IgE, IgM, IgD, and IgA) or any subclass (e.g., IgG1, IgG2, IgG3, IgG4, IgA1, and IgA2) of immunoglobulin molecules. Anti-SIRPα antibodies can be agonistic or antagonistic antibodies. Provided herein are antagonistic antibodies to SIRPα, including antibodies that reduce or block SIRPα signaling and / or block or reduce the binding between CD47 and SIRPα.

[0115] An "antigen" is a predetermined antigen to which an antibody can selectively bind. A target antigen can be a polypeptide, carbohydrate, nucleic acid, lipid, hapten, or other naturally occurring or synthetic compound. In some embodiments, the target antigen is a polypeptide.

[0116] The terms "antigen-binding fragment," "antigen-binding domain," "antigen-binding region," and similar terms refer to the portion of an antibody comprising the amino acid residues (e.g., CDRs) that interact with an antigen and confer specificity and affinity on the binding agent for the antigen.

[0117] The term "binds" or "binding" refers to interactions between molecules, including, for example, to form a complex. The interactions can be, for example, non-covalent interactions, including hydrogen bonds, ionic bonds, hydrophobic interactions and / or van der Waals interactions. A complex can also include two or more molecules bound together by covalent or non-covalent bonds, interactions or forces. The total non-covalent interaction strength between a single antigen binding site on an antibody and a single epitope of a target molecule (such as SIRPα) is the affinity of the antibody or functional fragment for that epitope. The dissociation rate (k) of an antibody for a monovalent antigen is 解离 ) and binding rate (k 结合 ) ratio (k 解离 / k 结合 ) is the dissociation constant K D, the dissociation constant is inversely proportional to the affinity. K D The lower the value, the higher the antibody affinity. D The value varies for different complexes of antibody and antigen and depends on the k 结合 and k 解离 The dissociation constant K of the antibodies provided herein is D Any method provided herein or any other method known to those skilled in the art can be used for determination. The affinity at one binding site cannot always reflect the true interaction strength between the antibody and the antigen. When a complex antigen containing multiple repeated antigenic determinants (such as multivalent SIRPα) contacts an antibody containing multiple binding sites, the interaction between the antibody and the antigen at one site will increase the probability of reaction at the second site. This type of multiple interaction strength between a multivalent antibody and an antigen is called avidity. Compared with the affinity of the individual binding sites of an antibody, the avidity of an antibody can be a better measure of its binding ability. For example, high affinity can make up for low affinity, and sometimes it may be found that the affinity of a pentameric IgM antibody is lower than that of IgG, but the high affinity of IgM due to its multivalency enables it to effectively bind to the antigen.

[0118] The terms "antibody that specifically binds to SIRPα", "antibody that specifically binds to a SIRPα epitope" and similar terms are also used interchangeably herein and refer to an antibody that specifically binds to a SIRPα polypeptide (such as a SIRPα antigen, or a fragment, or an epitope (such as human SIRPα, such as a human SIRPα polypeptide, antigen or epitope)). An antibody that specifically binds to SIRPα (such as human SIRPα) can bind to the extracellular domain of SIRPα or a peptide derived from the extracellular domain. An antibody that specifically binds to a SIRPα antigen (such as human SIRPα) can cross-react with a related antigen (such as cynomolgus monkey SIRPα). In certain embodiments, an antibody that specifically binds to a SIRPα antigen does not cross-react with other antigens. An antibody that specifically binds to a SIRPα antigen can be detected by, for example, immunoassays, Or other techniques known to those skilled in the art. When the antibody binds to the SIRPα antigen with a higher affinity than any cross-reactive antigen (as determined using experimental techniques such as radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA)), the antibody specifically binds to the SIRPα antigen. Typically, the specific or selective reaction is at least two times the background signal or noise and can exceed 10 times the background. For a discussion of antibody specificity, see, e.g., Fundamental Immunology332-36 (Paul ed., 2d ed., 1989). An antibody that "binds to an antigen of interest (e.g., a target antigen, such as SIRPα)" is an antibody that binds to the antigen with sufficient affinity to make the antibody suitable for use as a therapeutic agent targeting cells or tissues expressing the antigen and does not significantly cross-react with other proteins. In such embodiments, the extent of antibody binding to "non-target" proteins is less than about 10% of the binding of the antibody to its specific target protein, for example as determined by fluorescence activated cell sorting (FACS) analysis or RIA. With respect to the binding of an antibody to a target molecule, the term "specific binding," "specifically binds to," or "specifically for" a specific polypeptide or an epitope on a specific polypeptide target means that the binding is measurably different from non-specific interactions. Specific binding can be measured, for example, by comparing binding to a control molecule, or measuring the binding of a molecule, which is typically a molecule of similar structure that does not have binding activity. For example, specific binding can be determined based on competition with a control molecule that is similar to the target (e.g., an excess of unlabeled target). In this case, specific binding is indicated if an excess of unlabeled target competitively inhibits the binding of the labeled target to the probe. The term "anti-SIRPα antibody" or "antibody that binds to SIRPα" includes antibodies that are capable of binding to SIRPα with an affinity sufficient to make the antibody suitable for use as, for example, an agent targeting SIRPα. As used herein, the terms "specifically bind," "specifically bind to," or "specifically for" a particular polypeptide or an epitope on a particular polypeptide target refer to binding wherein the molecule binds to a particular polypeptide or an epitope on a particular polypeptide without substantially binding to any other polypeptide or polypeptide epitope. In certain embodiments, the antibody that binds to SIRPα has a dissociation constant (K) of less than or equal to 10nM, 5nM, 4nM, 3nM, 2nM, 1nM, 0.9nM, 0.8nM, 0.7nM, 0.6nM, 0.5nM, 0.4nM, 0.3nM, 0.2nM or 0.1nM. D In certain embodiments, the anti-SIRPα antibody binds to an epitope of SIRPα that is conserved between SIRPα from different species (e.g., between human and cynomolgus monkey SIRPα). In some embodiments, the anti-SIRPα antibody binds to an epitope of SIRPα that is a region that contacts CD47 when CD47 binds to SIRPα.

[0119] The term "compete" when used in the context of anti-SIRPα antibodies (e.g., antagonist antibodies and binding proteins that bind to SIRPα and compete for the same epitope or binding site on the target), means competition as determined by an assay in which the antibody (or binding fragment) under investigation prevents or inhibits specific binding of a reference molecule (e.g., a reference ligand or a reference antigen binding protein, such as a reference antibody) to a common antigen (e.g., SIRPα or a fragment thereof). Various types of competitive binding assays can be utilized to determine whether a test antibody competes with a reference antibody for binding to SIRPα (e.g., human SIRPα). Examples of assays that can be used include solid phase direct or indirect RIA, solid phase direct or indirect enzyme immunoassay (EIA), sandwich competition assays (see, e.g., Stahli et al., 1983, Methods in Enzymology 9:242-53), solid phase direct biotin-avidin EIA (see, e.g., Kirkland et al., 1986, J. Immunol. 137:3614-19), solid phase direct label assays, solid phase direct label sandwich assays (see, e.g., Harlow and Lane, 1986, J. Immunol. 137:3614-19). Antibodies,A Laboratory Manual (1988)), solid phase direct labeling RIA using I-125 labeling (see, e.g., Morel et al., 1988, Mol. Immunol. 25:7-15), and direct labeling RIA (Moldenhauer et al., 1990, Scand. J. Immunol. 32:77-82). Typically, such assays involve the use of purified antigen (e.g., SIRPα, such as human SIRPα) bound to a solid surface, or cells with an unlabeled test antigen binding protein (e.g., a test anti-SIRPα antibody) or a labeled reference antigen binding protein (e.g., a reference anti-SIRPα antibody). Competitive inhibition can be measured by measuring the amount of label bound to the solid surface or cells in the presence of the test antigen binding protein. Typically, the test antigen binding protein is present in excess. Antibodies identified by competition assays (competing antibodies) include antibodies that bind to the same epitope as the reference antibody, and / or antibodies that bind to an adjacent epitope that is sufficiently close to the epitope bound by the reference antibody so that the antibody is sterically hindered. Additional details about methods for determining competitive binding are described herein. Typically, when the competing antibody protein is present in excess, it inhibits specific binding of the reference antibody to the common antigen by at least 30%, such as 40%, 45%, 50%, 55%, 60%, 65%, 70%, or 75%. In some instances, binding is inhibited by at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or more.

[0120] The antibody of " separation " is substantially free of cellular material or other contaminating proteins from cell or tissue sources and / or other contaminant components produced when deriving the antibody, or is substantially free of chemical precursors or other chemicals when chemically synthesized. The language "substantially free of cellular material" includes antibody preparations in which the antibody is separated from the cellular components of the cells from which the antibody is separated or recombinantly produced. Therefore, antibodies substantially free of cellular material include antibody preparations with less than about 30%, 25%, 20%, 15%, 10%, 5% or 1% (by dry weight) heterologous proteins (also referred to herein as "contaminating proteins"). In certain embodiments, when the antibody is recombinantly produced, it is substantially free of culture medium, such as culture medium that accounts for less than about 20%, 15%, 10%, 5% or 1% of the volume of the protein preparation. In certain embodiments, when the antibody is produced by chemical synthesis, it is substantially free of chemical precursors or other chemicals, such as it is separated from chemical precursors or other chemicals involved in protein synthesis. Thus, such antibody preparations have less than about 30%, 25%, 20%, 15%, 10%, 5% or 1% (by dry weight) of chemical precursors or compounds other than the antibody of interest. Contaminant components may also include, but are not limited to, materials that interfere with therapeutic uses of the antibody and may include enzymes, hormones and other proteinaceous or non-proteinaceous solutes. In certain embodiments, the antibody is purified to (1) greater than 95% antibody by weight as determined by the Lowry method (Lowry et al., 1951, J. Bio. Chem. 193:265-75), such as 96%, 97%, 98% or 99%; (2) to a degree sufficient to obtain at least 15 residues of N-terminal or internal amino acid sequence (by using a spinning cup sequenator); (3) homogeneous by SDS-PAGE under reducing or non-reducing conditions using Coomassie blue or silver stain. Isolated antibodies include antibodies in situ within recombinant cells, as at least one component of the antibody's natural environment will be absent. Ordinarily, however, isolated antibodies will be prepared by at least one purification step.In certain embodiments, the antibodies provided herein are isolated.

[0121] The 4-chain antibody unit is a heterotetrameric glycoprotein, which is composed of two identical light (L) chains and two identical heavy (H) chains. In the case of lgG, the 4-chain unit is generally about 150,000 daltons. Each L chain is connected to the H chain via a covalent disulfide bond, and the two H chains are connected to each other via one or more disulfide bonds, depending on the H chain isotype. Each H chain and L chain also have regularly spaced intrachain disulfide bridges. Each H chain has a variable domain (VH) at the N-terminus, followed by three constant domains (CH) (for each of α and γ chains) and four CH domains (for μ and ε isotypes). Each L chain has a variable domain (VL) at the N-terminus, followed by a constant domain (CL) at its other end. VL aligns with VH, and CL aligns with the first constant domain (CH1) of the heavy chain. It is believed that specific amino acid residues form an interface between the light chain and the heavy chain variable domain. Paired VH and VL form a single antigen binding site together. For the structure and properties of different classes of antibodies, see e.g. Basic and Clinical Immunology 71 (Stites et al., ed., 8th ed., 1994).

[0122] The terms "variable region," "variable domain," "V region," or "V domain" refer to a portion of an antibody's light or heavy chain that is typically located at the amino terminus of the light or heavy chain and has a length of about 120 to 130 amino acids in the heavy chain and about 100 to 110 amino acids in the light chain, and is responsible for the binding and specificity of each particular antibody for its specific antigen. The heavy chain variable region may be referred to as "VH." The light chain variable region may be referred to as "VL." The term "variable" refers to the fact that the sequence of certain segments of the variable region differs widely between antibodies. The V region mediates antigen binding and defines the specificity of a particular antibody for its specific antigen. However, variability is not evenly distributed across the 110 amino acid span of the variable region. Instead, the V domain consists of less variable (e.g., relatively constant) segments of about 15-30 amino acids, called framework regions (FRs), separated by shorter regions of greater variability (e.g., extreme variability), called "hypervariable regions," each about 9-12 amino acids long. The variable regions of the heavy and light chains each comprise four FRs, essentially adopting a β-sheet configuration, connected by three hypervariable regions that form loops connecting, and in some cases forming part of, the β-sheet structure. The hypervariable regions in each chain are held together tightly by the FRs with those from the other chains, contributing to the formation of the antigen-binding site of the antibody (see, e.g., Kabat et al., Sequences of Proteins of Immunological Interest(5th edition, 1991)). The constant region is not directly involved in the binding of the antibody to the antigen, but exhibits various effector functions, such as enabling the antibody to participate in antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). The sequence of the variable region varies widely between different antibodies. In certain embodiments, the variable region is a human variable region.

[0123] The term "variable region residue numbering as in Kabat" or "amino acid position numbering as in Kabat" and variations thereof refer to the numbering system used by Kabat et al. (supra) to compile antibody heavy chain variable regions or light chain variable regions. Using this numbering system, the actual linear amino acid sequence may contain fewer or additional amino acids corresponding to shortening or insertion of the FR or CDR of the variable domain. For example, the heavy chain variable domain may include a single amino acid insertion after residue 52 (residue 52a, according to Kabat) and three inserted residues after residue 82 (e.g., residues 82a, 82b, and 82c, etc., according to Kabat). The Kabat numbering of the residues of a given antibody can be determined by alignment with the "standard" Kabat numbering sequence in homologous regions of the antibody sequence. When referring to the residues in the variable domain (approximately residues 1-107 of the light chain and residues 1-113 of the heavy chain), the Kabat numbering system (e.g., Kabat et al., supra) is generally used. When referring to residues in the constant region of an immunoglobulin heavy chain, the "EU numbering system" or "EU index" (e.g., the EU index as reported by Kabat et al., supra) is generally used. The "EU index as in Kabat" refers to the residue numbering of the human IgG1 EU antibody. Other numbering systems have been described, for example, by AbM, Chothia, Contact, IMGT, and AHon.

[0124] An "intact" antibody is an antibody that comprises an antigen binding site, CL, and at least heavy chain constant regions, CH1, CH2, and CH3. The constant region may comprise a human constant region or an amino acid sequence variant thereof. In certain embodiments, an intact antibody has one or more effector functions.

[0125] "Antibody fragments" comprise a portion of an intact antibody, such as the antigen-binding or variable region of an intact antibody. Examples of antibody fragments include, but are not limited to, Fab, Fab', F(ab')2, and Fv fragments; diabodies and di-diabodies (see, e.g., Holliger et al., 1993, Proc. Natl. Acad. Sci. 90:6444-48; Lu et al., 2005, J. Biol. Chem. 280:19665-72; Hudson et al., 2003, Nat. Med. 9:129-34; WO 93 / 11161; and U.S. Patent Nos. 5,837,242 and 6,492,123); single-chain antibody molecules (see, e.g., U.S. Patent Nos. 4,946,778; 5,260,203; 5,482,858; and 5,476,786); dual variable domain antibodies (see, e.g., U.S. Patent No. 7,612,181); single variable domain antibodies (sdAbs) (see, e.g., Woolven et al., 1999, Immunogenetics 50:98-101; and Streltsov et al., 2004, Proc Natl Acad Sci USA. 101:12444-49); and multispecific antibodies formed from antibody fragments.

[0126] A "functional fragment," "binding fragment," or "antigen-binding fragment" of a therapeutic antibody will exhibit at least one, if not some or all, of the biological functions attributed to the intact antibody, including at least binding to a target antigen (e.g., a SIRPα binding fragment or a fragment that binds to SIRPα).

[0127] As used herein, the term "fusion protein" refers to a polypeptide comprising the amino acid sequence of an antibody and the amino acid sequence of a heterologous polypeptide or protein, such as a polypeptide or protein that is not normally a part of an antibody (e.g., a non-anti-SIRPα antigen-binding antibody). The term "fusion" when used in conjunction with SIRPα or an anti-SIRPα antibody refers to the connection of a peptide or polypeptide, or a fragment, variant and / or derivative thereof, to a heterologous peptide or polypeptide. In certain embodiments, the fusion protein retains the biological activity of SIRPα or an anti-SIRPα antibody. In certain embodiments, the fusion protein comprises an anti-SIRPα antibody VH region, a VL region, a VH CDR (one, two or three VH CDRs), and / or a VL CDR (one, two or three VL CDRs), wherein the fusion protein binds to a SIRPα epitope, a SIRPα fragment and / or a SIRPα polypeptide.

[0128] The term "heavy chain", when used in conjunction with an antibody, refers to a polypeptide chain of about 50-70 kDa, wherein the amino-terminal portion includes a variable region of about 120 to 130 or more amino acids, and the carboxyl-terminal portion includes a constant region. Based on the amino acid sequence of the heavy chain constant region, the constant region can be one of five different types (e.g., isotypes), referred to as alpha (α), delta (δ), epsilon (ε), gamma (γ), and mu (μ). Different heavy chains have different sizes: α, δ, and γ contain about 450 amino acids, while μ and ε contain about 550 amino acids. These different types of heavy chains, when combined with light chains, produce the five well-known antibody classes (e.g., isotypes), namely IgA, IgD, IgE, IgG, and IgM, including the four subclasses of IgG, namely IgG1, IgG2, IgG3, and IgG4. The heavy chain can be a human heavy chain.

[0129] The term "light chain," when used in conjunction with an antibody, refers to a polypeptide chain of about 25 kDa, wherein the amino-terminal portion includes a variable region of about 100 to about 110 or more amino acids, and the carboxyl-terminal portion includes a constant region. The approximate length of a light chain is 211 to 217 amino acids. Based on the amino acid sequence of the constant domain, there are two different types, designated kappa (κ) or lambda (λ). Light chain amino acid sequences are well known in the art. The light chain may be a human light chain.

[0130] As used herein, the term "host" refers to an animal, such as a mammal (eg, a human).

[0131] As used herein, the term "host cell" refers to a specific subject cell that can be transfected with a nucleic acid molecule and the progeny or potential progeny of such a cell. The progeny of such a cell may not be identical to the parent cell transfected with the nucleic acid molecule due to mutations or environmental influences that may occur in subsequent generations or due to integration of the nucleic acid molecule into the host cell genome.

[0132] As used herein, the term "monoclonal antibody" refers to an antibody obtained from a substantially homogeneous population of antibodies, e.g., the individual antibodies comprising the population are identical except for possible naturally occurring mutations that may be present in small amounts, and each monoclonal antibody will typically recognize a single epitope on the antigen. In specific embodiments, as used herein, a "monoclonal antibody" is an antibody produced by a single hybridoma or other cell, wherein the antibody binds only to a SIRPα epitope, as determined, for example, by ELISA or other antigen binding or competitive binding assays known in the art. The term "monoclonal" is not limited to any particular method for preparing antibodies. For example, monoclonal antibodies suitable for use in the present disclosure can be prepared by the hybridoma method first described by Kohler et al., 1975, Nature 256:495, or can be prepared using recombinant DNA methods in bacteria or eukaryotic animal or plant cells (see, e.g., U.S. Patent No. 4,816,567). "Monoclonal antibodies" can also be isolated from phage antibody libraries using techniques such as those described in Clackson et al., 1991, Nature 352:624-28 and Marks et al., 1991, J. Mol. Biol., 222:581-97. Other methods for preparing clonal cell lines and monoclonal antibodies expressed thereby are well known in the art. See, for example, Short Protocols in Molecular Biology (Ausubel et al., eds., 5th ed., 2002.) Exemplary methods for generating monoclonal antibodies are provided herein in the Examples.

[0133] The term "native" when used in connection with biological materials (such as nucleic acid molecules, polypeptides, host cells, etc.) refers to those found in nature and have not been manipulated, modified and / or changed (e.g., isolated, purified, selected) by man.

[0134] The antibodies provided herein may include "chimeric" antibodies in which a portion of the heavy and / or light chain is identical or homologous to the corresponding sequence in antibodies derived from a particular species or belonging to a particular antibody class or subclass, while the remainder of the chain is identical or homologous to the corresponding sequence in antibodies derived from another species or belonging to another antibody class or subclass; as well as fragments of such antibodies, so long as they exhibit the desired biological activity (see U.S. Pat. No. 4,816,567; and Morrison et al., 1984, Proc. Natl. Acad. Sci. USA 81:6851-55).

[0135] In some embodiments, the humanized antibody comprises a chimeric antibody comprising a human immunoglobulin (e.g., a recipient antibody), wherein the native CDR residues are replaced with residues of corresponding CDRs from non-human species (e.g., donor antibodies) (e.g., mice, rats, rabbits, or non-human primates) with desired specificity, affinity, and ability. In some cases, one or more FR region residues of the human immunoglobulin are replaced with corresponding non-human residues. In addition, the humanized antibody may comprise residues not found in the recipient antibody or the donor antibody. These modifications are carried out in order to further improve antibody potency. The humanized antibody heavy chain or light chain may comprise substantially all of at least one or more variable regions, wherein all or substantially all of the CDRs correspond to the CDRs of non-human immunoglobulins and all or substantially all of the FRs are FRs of human immunoglobulin sequences. In certain embodiments, the humanized antibody will comprise at least a portion of an immunoglobulin constant region (Fc), typically at least a portion of a human immunoglobulin. For additional details, see Jones et al., 1986, Nature 321:522-25; Riechmann et al., 1988, Nature 332:323-29; Presta, 1992, Curr. Op. Struct. Biol. 2:593-96; Carter et al., 1992, Proc. Natl. Acad. Sci. USA 89:4285-89; U.S. Patent Nos. 6,800,738; 6,719,971; 6,639,055; 6,407,213; and 6,054,297.

[0136] A "human antibody" is an antibody whose amino acid sequence corresponds to the amino acid sequence of an antibody produced by a human and / or has been prepared using any of the human antibody preparation techniques disclosed herein. This definition of a human antibody specifically excludes humanized antibodies comprising non-human antigen-binding residues. Human antibodies can be produced using various techniques known in the art, including phage display libraries (Hoogenboom and Winter, 1991, J. Mol. Biol. 227:381; Marks et al., 1991, J. Mol. Biol. 222:581) and yeast display libraries (Chao et al., 2006, Nature Protocols 1:755-68). Cole et al., Monoclonal Antibodies and Cancer Therapy77 (1985); Boerner et al., 1991, J. Immunol. 147(1):86-95; and the methods described in van Dijk and van de Winkel, 2001, Curr. Opin. Pharmacol. 5:368-74 can also be used to prepare human monoclonal antibodies. Human antibodies can be prepared by administering an antigen to a transgenic animal, such as a mouse, that has been modified to produce such antibodies in response to antigenic challenge, but in which the endogenous loci have been disabled (see, e.g., Jakobovits, 1995, Curr. Opin. Biotechnol. 6(5):561-66; Brüggemann and Taussing, 1997, Curr. Opin. Biotechnol. 8(4):455-58; and for the XENOMOUSE TM For human antibodies generated via human B cell hybridoma technology, see also, for example, Li et al., 2006, Proc. Natl. Acad. Sci. USA, 103:3557-62.

[0137] "CDR" refers to one of the three hypervariable regions (H1, H2, or H3) within the non-framework region of the immunoglobulin (Ig or antibody) VH β sheet framework, or one of the three hypervariable regions (L1, L2, or L3) within the non-framework region of the antibody VL β sheet framework. Thus, CDRs are variable region sequences interspersed within the framework region sequences. CDR regions are well known to those skilled in the art and have been defined by, for example, Kabat as the most highly variable regions within the variable (V) domain of an antibody (Kabat et al., 1997, J. Biol. Chem. 252: 6609-16; Kabat, 1978, Adv. Prot. Chem. 32: 1-75). CDR region sequences are also structurally defined by Chothia as those residues that are not part of the conserved β sheet framework and are therefore able to adapt to different conformations (Chothia and Lesk, 1987, J. Mol. Biol. 196: 901-17). Both terms are well known in the art. CDR region sequences are also defined by AbM, Contact, and IMGT. The positions of CDRs in typical antibody variable regions have been determined by comparison of a large number of structures (Al-Lazikani et al., 1997, J. Mol. Biol. 273:927-48; Morea et al., 2000, Methods 20:267-79). Since the number of residues in the hypervariable region varies from antibody to antibody, the residue numbers in the typical variable region numbering scheme are conventionally numbered with a, b, c, etc. relative to other residues in the typical position (Al-Lazikani et al., supra). Such nomenclature is similarly known to those skilled in the art.

[0138] The term "hypervariable region", "HVR" or "HV" when used herein refers to the region of the antibody variable region whose sequence has high variability and / or forms a structurally defined loop. In general, antibodies contain six hypervariable regions; three are located in VH (H1, H2, H3) and three are located in VL (L1, L2, L3). A variety of hypervariable region descriptions are used and encompassed herein. The Kabat complementarity determining regions (CDRs) are based on sequence variability and are most commonly used (see, e.g., Kabat et al., supra). Chothia actually mentions the position of the structural loops (see, e.g., Chothia and Lesk, 1987, J. Mol. Biol. 196:901-17). When numbered using the Kabat numbering convention, the terminus of the Chothia CDR-H1 loop varies between H32 and H34, depending on the length of the loop (because the Kabat numbering scheme places the insert at H35A and H35B; if neither 35A nor 35B is present, the loop terminus is at 32; if only 35A is present, the loop terminus is at 33; and if both 35A and 35B are present, the loop terminus is at 34). The AbM hypervariable regions represent the balance between the Kabat CDRs and the Chothia structural loops and are utilized by Oxford Molecular's AbM antibody modeling software (see, e.g., Antibody Engineering Volume 2 (Kontermann and Dübel eds., 2nd ed., 2010)). The "contact" hypervariable regions are based on analysis of the available complex crystal structure. The residues from each of these hypervariable regions or CDRs are indicated below.

[0139] Recently, a universal numbering system, ImMunoGeneTics (IMGT) Information, has been developed and widely adopted. (Lafranc et al., 2003, Dev. Comp. Immunol. 27(1):55-77). IMGT is an integrated information system dedicated to immunoglobulins (IGs), T cell receptors (TCRs), and major histocompatibility complexes (MHCs) of humans and other vertebrates. Herein, CDRs are referred to based on the amino acid sequence and the position within the light or heavy chain. Since the "position" of CDRs within the immunoglobulin variable domain structure is conserved between species and is present in structures called loops, CDRs and framework residues are easily identified using a numbering system that aligns variable domain sequences based on structural features. This information can be used to transplant and replace CDR residues from immunoglobulins from one species into a receptor framework typically from a human antibody. Another numbering system (AHon) has been developed by Honegger and Plückthun, 2001, J. Mol. Biol. 309:657-70. The identity between numbering systems, including, for example, Kabat numbering and the IMGT unique numbering system, is well known to those skilled in the art (see, for example, Kabat, supra; Chothia and Lesk, supra; Martin, supra; Lefranc et al., supra).

[0140]

[0141]

[0142] The hypervariable region may comprise the following "extended hypervariable region": 24-36 or 24-34 (L1), 46-56 or 50-56 (L2) and 89-97 or 89-96 (L3) in VL; and 26-35 or 26-35A (H1), 50-65 or 49-65 (H2) and 93-102, 94-102 or 95-102 (H3) in VH. As used herein, the terms "HVR" and "CDR" are used interchangeably.

[0143] The term "constant region" or "constant domain" refers to the carboxyl-terminal portion of the light and heavy chains that is not directly involved in antibody binding to antigen, but exhibits various effector functions, such as interaction with Fc receptors. The term refers to a portion of the immunoglobulin molecule that has a more conserved amino acid sequence than the other portion of the immunoglobulin (the variable region) that contains the antigen binding site. The constant region may contain the CH1, CH2, and CH3 regions of the heavy chain and the CL region of the light chain.

[0144] The term "framework" or "FR" refers to those variable region residues that flank the CDRs. FR residues are found, for example, in chimeric, humanized, human, domain antibodies, diabodies, linear antibodies, and bispecific antibodies. FR residues are those variable domain residues other than the hypervariable region residues or CDR residues.

[0145] An "affinity matured" antibody is an antibody that has one or more alterations (e.g., amino acid sequence variations, including changes, additions, and / or deletions) in one or more HVRs that improve the affinity of the antibody for the antigen, compared to a parent antibody that does not have those alterations. Affinity matured antibodies can have nanomolar or even picomolar affinities for the target antigen. Affinity matured antibodies are produced by procedures known in the art. For review, see Hudson and Souriau, 2003, Nature Medicine 9:129-34; Hoogenboom, 2005, Nature Biotechnol. 23:1105-16; Quiroz and Sinclair, 2010, Revista Ingeneria Biomedia 4:39-51.

[0146] "Binding affinity" generally refers to the sum of the strengths of non-covalent interactions between a single binding site of a molecule (e.g., a binding protein such as an antibody) and its binding partner (e.g., an antigen). Unless otherwise indicated, as used herein, "binding affinity" refers to the intrinsic binding affinity that reflects a 1:1 interaction between members of a binding pair (e.g., an antibody and an antigen). The affinity of a binding molecule X for its binding partner Y can generally be expressed by the dissociation constant (K) D ) represents. Affinity can be measured by common methods known in the art (including the methods described herein). Low-affinity antibodies generally bind antigen slowly and tend to dissociate easily, while high-affinity antibodies generally bind antigen faster and tend to remain bound for a longer time. A variety of methods for measuring binding affinity are known in the art, any of which can be used for the purposes of the present disclosure. Specific illustrative embodiments include the following. In one embodiment, "K D ” or “K D The "value" can be measured by assays known in the art, such as by binding assays. D It can be measured using RIA, for example, using a Fab form of the antibody of interest and its antigen (Chen et al., 1999, J. Mol Biol 293:865-81). D or K D The value can also be passed Surface plasmon resonance is used for measurement, for example TM-2000 or TM-3000, or use e.g. QK384 system, measured by biolayer interferometry. "On-rate" or "rate of association" or "association rate" or "k 结合 (k on )" can also utilize the same surface plasmon resonance or biolayer interferometry techniques described above, using, for example TM-2000 or TM-3000 or The assay was performed using the QK384 system.

[0147] The phrase "substantially similar" or "substantially identical" means that the degree of similarity between two values ​​(e.g., one associated with an antibody of the invention and the other associated with a reference antibody) is sufficiently high that one skilled in the art would consider the difference between the two values ​​to be minimal or not biologically and / or statistically significant within the context of the biological characteristics measured by the values. For example, the difference between the two values ​​can be less than about 50%, less than about 40%, less than about 30%, less than about 20%, less than about 10%, or less than about 5%, depending on the value of the reference antibody.

[0148] As used herein, the phrase "substantially increased" or "substantially decreased" or "substantially different" means that the similarity between two values ​​(e.g., one associated with an antibody of the invention and the other associated with a reference antibody) is sufficiently high that one of skill in the art would consider the difference between the two values ​​to be statistically significant within the context of the biological characteristics measured by the values. For example, the difference between the two values ​​can be greater than about 10%, greater than about 20%, greater than about 30%, greater than about 40%, or greater than about 50%, depending on the value of the reference antibody.

[0149] Antibody "effector functions" refer to those biological activities attributable to the Fc region (e.g., a native sequence Fc region or an amino acid sequence variant Fc region) of an antibody and vary according to the antibody isotype. Examples of antibody effector functions include: C1q binding; CDC; Fc receptor binding; and ADCC.

[0150] As used herein, the term "effective amount" refers to an amount of an antibody or pharmaceutical composition provided herein sufficient to produce a desired result.

[0151] As used herein, the term "Fc region" is used to define the C-terminal region of an immunoglobulin heavy chain, including, for example, native sequence Fc regions, recombinant Fc regions, and variant Fc regions. Although the boundaries of the Fc region of an immunoglobulin heavy chain may vary, the human IgG heavy chain Fc region is generally defined as the amino acid residue at position Cys226 or the fragment from Pro230 to its carboxyl terminus. The C-terminal lysine (residue 447, according to the EU numbering system) in the Fc region can be removed, for example, during the preparation or purification of the antibody, or by recombinantly engineering the nucleic acid encoding the heavy chain of the antibody. Thus, the composition of a complete antibody can include antibody groups in which all K447 residues are removed, antibody groups in which the K447 residue is not removed, and antibody groups containing a mixture of antibodies with and without the K447 residue.

[0152] A "functional Fc fragment" possesses the "effector functions" of a native sequence Fc region. Exemplary "effector functions" include C1q binding; CDC; Fc receptor binding; ADCC; phagocytosis; downregulation of cell surface receptors (e.g., B cell receptors), etc. Such effector functions generally require combining the Fc region with a binding region or domain (e.g., an antibody variable region or domain) and can be assessed using the various assays disclosed.

[0153] A "native sequence Fc region" comprises an amino acid sequence identical to the amino acid sequence of an Fc region found in nature and has not been manipulated, modified, and / or altered by humans (e.g., isolated, purified, selected, included, or combined with other sequences (such as variable region sequences). Native sequence human IgG1 Fc regions include native sequence human IgG1 Fc regions (non-A and A allotypes); native sequence human IgG2 Fc regions; native sequence human IgG3 Fc regions; and native sequence human IgG4 Fc regions and naturally occurring variants thereof. For example, the native human IgG1 Fc region amino acid sequence is provided below: ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKC KVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK (SEQ ID NO:155, highlighting K322).

[0154] An exemplary native human IgG4 Fc region sequence is provided as follows: ASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTKTYTCNVDHKPSNTKVDKRVESKYGPPCP S CPAPEF L GGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK (SEQ ID NO:156, highlighting S228 and L235).

[0155] A "variant Fc region" comprises an amino acid sequence that differs from a native sequence Fc region by at least one amino acid modification (e.g., substitution, addition, or deletion). In certain embodiments, the variant Fc region has at least one amino acid substitution in the native sequence Fc region or in the Fc region of the parent polypeptide, such as from about one to about ten amino acid substitutions or from about one to about five amino acid substitutions, compared to the native sequence Fc region or to the Fc region of the parent polypeptide. Herein, the variant Fc region may have at least about 80% homology to the native sequence Fc region and / or the parent polypeptide Fc region, or at least about 90% homology thereto, such as at least about 95% homology thereto. For example, a variant IgG1-K322A Fc region in which an amino acid K at position 322 of the human IgG1 Fc amino acid sequence is changed to an A is provided as follows: ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKC A VSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK (SEQ ID NO: 157, K322A substitution highlighted).

[0156] An exemplary variant IgG1-AAS Fc region in which the two amino acids LL at positions 234-235 are changed to AA and the amino acid D at position 265 is changed to S is provided as follows: ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPE AA GGPSVFLFPPKPKDTLMISRTPEVTCVVV SVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK (SEQ ID NO: 144, substitutions of AA for LL and S for D are highlighted).

[0157] An exemplary variant IgG4P Fc region in which one amino acid S at position 228 of the human IgG4 Fc amino acid sequence is changed to P is provided as follows: ASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTKTYTCNVDHKPSNTKVDKRVESKYGPPCP P CPAPEFLGPSVFLFPPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKA KGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK(SEQ ID NO:158, S228P substitution highlighted).

[0158] An exemplary variant IgG4PE Fc region in which two amino acids at positions 228 and 235 of the human IgG4 Fc amino acid sequence are changed is provided below:

[0159] ASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTKTYTCNVDHKPSNTKVDKRVESKYGPPCP P CPAPEF EGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQP REPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK(SEQ ID NO:159, S228P and L235E superseded highlighted).

[0160] The term "variant" when used in conjunction with an anti-SIRPα antibody refers to a peptide or polypeptide that comprises one or more (such as about 1 to about 25, about 1 to about 20, about 1 to about 15, about 1 to about 10, or about 1 to about 5) amino acid sequence substitutions, deletions and / or additions compared to the native or unmodified sequence. For example, a variant of an anti-SIRPα antibody may be produced by one or more (such as about 1 to about 25, about 1 to about 20, about 1 to about 15, about 1 to about 10, or about 1 to about 5) changes in the amino acid sequence of a native or previously unmodified anti-SIRPα antibody. Anti-SIRPα antibody variants may be naturally occurring, such as alleles or splice variants, or may be artificially constructed. Anti-SIRPα antibody variants may be prepared from corresponding nucleic acid molecules encoding the variants. In specific embodiments, the anti-SIRPα antibody variants at least retain the functional activity of the anti-SIRPα antibody (e.g., antagonistic activity against CD47 binding and / or CD47-induced SIRPα signaling). In certain embodiments, the anti-SIRPα antibody variants bind to SIRPα and / or antagonize CD47 binding to SIRPα and / or SIRPα activity. In certain embodiments, the variants are encoded by single nucleotide polymorphism (SNP) variants of a nucleic acid molecule encoding an anti-SIRPα antibody VH or VL region or subregion, such as one or more CDRs.

[0161] The term "vector" refers to a substance that is used to carry or include a nucleic acid sequence, including, for example, a nucleic acid sequence encoding an anti-SIRPα antibody as described herein, so as to introduce the nucleic acid sequence into a host cell. Applicable vectors include, for example, expression vectors, plasmids, phage vectors, viral vectors, episomes, and artificial chromosomes, which may include a selection sequence or marker that can be operated to stably integrate into the host cell chromosome. In addition, the vector may include one or more selectable marker genes and appropriate expression control sequences. The selectable marker genes that may be included confer, for example, resistance to antibiotics or toxins, complement auxotrophic deficiencies, or supply key nutrients that are not present in the culture medium. Expression control sequences may include constitutive and inducible promoters, transcription enhancers, transcription terminators, and the like that are well known in the art. When two or more nucleic acid molecules are co-expressed (e.g., antibody heavy and light chains or antibody VH and VL), both nucleic acid molecules may be inserted into, for example, a single expression vector or separate expression vectors. For single vector expression, the encoding nucleic acid may be operably linked to a common expression control sequence, or to different expression control sequences, such as an inducible promoter and a constitutive promoter. The introduction of nucleic acid molecules into host cells can be confirmed using methods well known in the art. Such methods include, for example, nucleic acid analysis, such as Northern blotting or polymerase chain reaction (PCR) amplification of mRNA; or immunoblotting for expression of gene products, or other suitable analytical methods for testing the expression of introduced nucleic acid sequences or their corresponding gene products. It will be understood by those skilled in the art that the amount of nucleic acid molecules expressed is sufficient to produce the desired product (e.g., an anti-SIRPα antibody as described herein), and it will be further understood that expression levels can be optimized using methods well known in the art to achieve sufficient expression.

[0162] "Antibody-dependent cell-mediated cytotoxicity" or "ADCC" refers to a form of cytotoxicity in which secretory immunoglobulins bound to Fc receptors (FcRs) present on certain cytotoxic cells (e.g., natural killer (NK) cells, neutrophils, and macrophages) enable these cytotoxic effector cells to specifically bind to antigen-bearing target cells and subsequently kill the target cells with cytotoxins. Antibodies "arm" cytotoxic cells and are absolutely necessary for such killing. NK cells (the main cells for mediating ADCC) express only FcγRIII, while monocytes express FcγRI, FcγRII, and FcγRIII. FcR expression on hematopoietic cells is known (see, e.g., Ravetch and Kinet, 1991, Annu. Rev. Immunol. 9:457-92). In order to assess the ADCC activity of a molecule of interest, an in vitro ADCC assay can be performed (see, e.g., U.S. Patent Nos. 5,500,362 and 5,821,337). Suitable effector cells for such assays include peripheral blood mononuclear cells (PBMCs) and natural killer (NK) cells. Alternatively or additionally, ADCC activity of the molecule of interest in vivo (e.g., in an animal model) can be assessed (see, e.g., Clynes et al., 1998, Proc. Natl. Acad. Sci. USA 95: 652-56). Antibodies with little or no ADCC activity can be used.

[0163] "Antibody-dependent cellular phagocytosis" or "ADCP" refers to the destruction of target cells via monocyte- or macrophage-mediated phagocytosis when immunoglobulins bound to Fc receptors (FcRs) present on certain phagocytes (e.g., neutrophils, monocytes, and macrophages) enable these phagocytes to specifically bind to target cells carrying an antigen and subsequently kill the target cells. In order to assess the ADCP activity of a molecule of interest, an in vitro ADCP assay (see, e.g., Bracher et al., 2007, J. Immunol. Methods 323: 160-71) can be performed. Phagocytic cells suitable for such assays include peripheral blood mononuclear cells (PBMCs), purified monocytes from PBMCs, or U937 cells differentiated into a mononuclear type. Alternatively or in addition, the ADCP activity of a molecule of interest in vivo (e.g., in an animal model) can be assessed (see, e.g., Wallace et al., 2001, J. Immunol. Methods 248: 167-82). Antibodies with little or no ADCP activity can be used.

[0164] "Fc receptor" or "FcR" describes a receptor that binds to the Fc region of an antibody. An exemplary FcR is a native sequence human FcR. Additionally, an exemplary FcR is an FcR that binds to IgG antibodies (e.g., a gamma receptor) and includes receptors of the FcγRI, FcγRII, and FcγRIII subclasses, including allelic variants and alternative splice forms of these receptors. FcγRII receptors include FcγRIIA ("activating receptor") and FcγRIIB ("inhibiting receptor"), which are similar in amino acid sequence, differing primarily in their cytoplasmic domains (see, e.g., 1997, Annu. Rev. Immunol. 15: 203-34). Various FcRs are known (see, for example, Ravetch and Kinet, 1991, Annu. Rev. Immunol. 9: 457-92; Capel et al., 1994, Immunomethods 4: 25-34; and de Haas et al., 1995, J. Lab. Clin. Med. 126: 330-41). The term "FcR" herein encompasses other FcRs, including those to be identified in the future. The term also includes the neonatal receptor FcRn, which is responsible for the transfer of maternal IgG to the fetus (see, for example, Guyer et al., 1976, J. Immunol. 117: 587-93; and Kim et al., 1994, Eu. J. Immunol. 24: 2429-34). Antibody variants with improved or diminished binding to FcRs have been described (see, eg, WO 2000 / 42072; US Patent Nos. 7,183,387, 7,332,581, and 7,335,742; Shields et al., 2001, J. Biol. Chem. 9(2):6591-604).

[0165] "Complement-dependent cytotoxicity" or "CDC" refers to the lysis of target cells in the presence of complement. Activation of the classical complement pathway begins with the binding of the first component of the complement system (Clq) to an antibody (of the appropriate subclass) bound to its cognate antigen. To assess complement activation, a CDC assay can be performed (see, e.g., Gazzano-Santoro et al., 1996, J. Immunol. Methods 202:163). Polypeptide variants with altered Fc region amino acid sequences (polypeptides with variant Fc regions) and enhanced or decreased C1q binding ability have been described (see, e.g., U.S. Patent No. 6,194,551; WO 1999 / 51642; Idusogie et al., 2000, J. Immunol. 164:4178-84). Antibodies with little or no CDC activity can be selected.

[0166] A SIRPα polypeptide "extracellular domain" or "ECD" refers to a form of a SIRPα polypeptide that is substantially free of transmembrane and cytoplasmic domains. For example, a SIRPα polypeptide ECD may have less than 1% of such transmembrane and / or cytoplasmic domains and may have less than 0.5% of such domains.

[0167] The term "identity" refers to the relationship between the sequences of two or more polypeptide molecules or two or more nucleic acid molecules, as determined by alignment and comparison of the sequences. "Percentage (%) of amino acid sequence identity" relative to a reference polypeptide sequence is defined as the percentage of amino acid residues in the candidate sequence that are identical to the amino acid residues in the reference polypeptide sequence, after aligning the sequences and introducing gaps (if necessary) to achieve the maximum percentage of sequence identity, and any conservative substitutions are not considered part of the sequence identity. Alignment for the purpose of determining percentage of amino acid sequence identity can be achieved in various ways within the skill of the art, for example, using publicly available computer software such as BLAST, BLAST-2, ALIGN or MEGALIGN (DNAStar, Inc.) software. Those skilled in the art can determine the parameters applicable to alignment sequences, including any algorithm required to achieve maximum alignment over the full length of the compared sequences.

[0168] "Modification" of an amino acid residue / position refers to a change in the primary amino acid sequence compared to the starting amino acid sequence, wherein the change is due to a sequence variation involving the amino acid residue / position. For example, typical modifications include substitution of a residue by another amino acid (e.g., conservative or non-conservative substitution), insertion of one or more (e.g., typically less than 5, 4, or 3) amino acids adjacent to the residue / position, and / or deletion of the residue / position.

[0169] An "epitope" is a site on the surface of an antigen molecule to which a single antibody molecule binds, such as a localized area on the surface of an antigen (such as a SIRPα polypeptide, a SIRPα polypeptide fragment), which is capable of binding to one or more antigen-binding regions of an antibody and has antigenic or immunogenic activity capable of eliciting an immune response in an animal such as a mammal (e.g., a human). An epitope with immunogenic activity is a portion of a polypeptide that elicits an antibody response in an animal. An epitope with antigenic activity is a portion of a polypeptide to which an antibody binds, as determined by any method known in the art, including, for example, immunoassays. An antigenic epitope is not necessarily immunogenic. Epitopes are typically composed of chemically active surface groups of molecules such as amino acids or sugar side chains and have specific three-dimensional structural characteristics as well as specific charge characteristics. Antibody epitopes can be linear epitopes or conformational epitopes. Linear epitopes are formed by continuous amino acid sequences in proteins. Conformational epitopes are formed by amino acids that are discontinuous in a protein sequence but are bound together after the protein folds into its three-dimensional structure. Induced epitopes are formed when the three-dimensional structure of a protein is in an altered conformation, such as after activation or binding by another protein or ligand. In certain embodiments, a SIRPα epitope is a three-dimensional surface feature of a SIRPα polypeptide. In other embodiments, a SIRPα epitope is a linear feature of a SIRPα polypeptide. Typically, an antigen has several or more different epitopes and can react with many different antibodies.

[0170] When an antibody and a reference antibody recognize the same, overlapping, or adjacent epitopes in three-dimensional space, the two antibodies bind to an "epitope," "substantially the same epitope," or "the same epitope." The most widely used and rapid method for determining whether two antibodies bind to the same, overlapping, or adjacent epitopes in three-dimensional space is a competition assay, which can be configured in many different formats, for example, using labeled antigens or labeled antibodies. In some assays, the antigen is immobilized on a 96-well plate or expressed on the surface of cells, and a radioactive, fluorescent, or enzymatic label is used to measure the ability of an unlabeled antibody to block the binding of the labeled antibody.

[0171] "Epitope mapping" is a method of identifying an antibody's binding site or epitope for its target antigen. "Epitope grouping" is a method of grouping antibodies based on the epitope they recognize. More specifically, epitope grouping comprises methods and systems that utilize a combination of competition assays and computational methods to distinguish the epitope recognition properties of different antibodies, so as to cluster antibodies based on their epitope recognition properties and identify antibodies with different binding specificities.

[0172] As used herein, "carrier" includes a pharmaceutically acceptable carrier, excipient, or stabilizer that is nontoxic to the cells or mammals to which it is exposed at the dosages and concentrations used. Typically, a physiologically acceptable carrier is an aqueous pH buffered solution. Examples of physiologically acceptable carriers include buffers such as phosphates, citrates, and other organic acids; antioxidants including ascorbic acid; low molecular weight (e.g., less than about 10 amino acid residues) polypeptides; proteins such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, arginine, or lysine; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrins; chelating agents such as EDTA; sugar alcohols such as mannitol or sorbitol; salt-forming counterions such as sodium; and / or nonionic surfactants such as TWEEN®. TM , polyethylene glycol (PEG) and PLURONICS TM . The term "carrier" may also refer to a diluent, adjuvant (e.g., Freund's adjuvant (complete or incomplete)), excipient, or vehicle. Such carriers (including pharmaceutical carriers) may be sterile liquids, such as water and oils, including oils of petroleum, animal, plant, or synthetic origin, such as peanut oil, soybean oil, mineral oil, sesame oil, etc. When a composition (e.g., a pharmaceutical composition) is administered intravenously, water is an exemplary carrier. Physiological saline solutions, aqueous dextrose solutions, and glycerol solutions may also be used as liquid carriers, particularly for injectable solutions. Suitable excipients (e.g., pharmaceutical excipients) include starch, glucose, lactose, sucrose, gelatin, malt, rice, flour, chalk, silica gel, sodium stearate, glyceryl monostearate, talc, sodium chloride, skimmed milk, glycerol, propylene, glycol, water, ethanol, etc. If necessary, the composition may also contain a small amount of a wetting agent or emulsifier, or a pH buffer. The compositions can be in the form of solutions, suspensions, emulsions, tablets, pills, capsules, powders, sustained release formulations, and the like. Oral compositions (including formulations) can include standard carriers such as pharmaceutical grade mannitol, lactose, starch, magnesium stearate, sodium saccharin, cellulose, magnesium carbonate, and the like. Examples of suitable pharmaceutical carriers are described in Remington and Gennaro, Remington's Pharmaceutical Sciences (18th edition, 1990). Compositions comprising a pharmaceutical compound can contain an anti-SIRPα antibody (eg, in isolated or purified form) and a suitable carrier.

[0173] As used herein, the term "pharmaceutically acceptable" means approved by a regulatory agency of the Federal or a state government or listed in the US Pharmacopia, the European Pharmacopia, or other generally recognized pharmacopeia for use in animals, and more particularly in humans.

[0174] As used herein, "polyclonal antibody" refers to an antibody population produced in an immunogenic response to a protein with multiple epitopes and therefore includes a plurality of different antibodies directed against the same and different epitopes within the protein. Methods for producing polyclonal antibodies are known in the art (see, for example, Short Protocols in Molecular Biology (Ausubel et al., eds., 5th ed., 2002)).

[0175] "Isolated nucleic acid" refers to a nucleic acid, such as RNA, DNA, or mixed nucleic acid, that is substantially separated from other genomic DNA sequences and proteins or complexes (such as ribosomes and polymerases) of naturally occurring accompanying native sequences. "Isolated" nucleic acid molecules are nucleic acid molecules separated from other nucleic acid molecules present in the natural origin of the nucleic acid molecules. In addition, "isolated" nucleic acid molecules (such as cDNA molecules) can be substantially free of other cellular materials or culture media (when prepared by recombinant techniques), or substantially free of chemical precursors or other chemical substances (when chemically synthesized). In a specific embodiment, one or more nucleic acid molecules encoding antibodies as described herein are separated or purified. The term encompasses nucleic acid sequences removed from naturally occurring environments, and includes recombinant or cloned DNA isolates and chemically synthesized analogs or analogs biosynthesized by heterologous systems. Substantially pure molecules can include isolated molecular forms.

[0176] As used interchangeably herein, "polynucleotide" or "nucleic acid" refers to a polymer of nucleotides of any length and includes DNA and RNA. The nucleotides may be deoxyribonucleotides, ribonucleotides, modified nucleotides or bases and / or analogs thereof, or any substrate that can be incorporated into a polymer by DNA or RNA polymerase or by a synthetic reaction. Polynucleotides may contain modified nucleotides, such as methylated nucleotides and their analogs. As used herein, "oligonucleotide" refers to a short, usually single-stranded, synthetic polynucleotide that is typically (but not necessarily) less than about 200 nucleotides in length. The terms "oligonucleotide" and "polynucleotide" are not mutually exclusive. The above description of polynucleotides applies equally and fully to oligonucleotides. Cells that produce the anti-SIRPα antibodies of the present disclosure may include parent hybridoma cells, as well as bacterial and eukaryotic host cells into which nucleic acid encoding the antibody has been introduced. Suitable host cells are disclosed below.

[0177] Unless otherwise indicated, the left-hand end of any single-stranded polynucleotide sequence disclosed herein is referred to as the 5' end; the left-hand direction of a double-stranded polynucleotide sequence is referred to as the 5' direction. The 5' to 3' direction of addition of a nascent RNA transcript is referred to as the transcription direction; the sequence region on a DNA strand that has the same sequence as an RNA transcript and is 5' relative to the 5' end of the RNA transcript is referred to as the "upstream sequence"; the sequence region on a DNA strand that has the same sequence as an RNA transcript and is 3' relative to the 3' end of the RNA transcript is referred to as the "downstream sequence."

[0178] The term "recombinant antibody" refers to an antibody prepared, expressed, produced or separated by a recombinant manner. Recombinant antibodies can be antibodies expressed using a recombinant expression vector transfected into a host cell, antibodies separated from a recombinant combinatorial antibody library, antibodies separated from transgenic and / or transgenic chromosome animals (such as mice or cows) of human immunoglobulin genes (see, for example, Taylor et al., 1992, Nucl. Acids Res. 20: 6287-95), or antibodies prepared, expressed, produced or separated by any other means involving splicing of immunoglobulin gene sequences with other DNA sequences. Such recombinant antibodies can have variable regions and constant regions, including those derived from human germline immunoglobulin sequences (see Kabat et al., supra). However, in certain embodiments, such recombinant antibodies may be subjected to in vitro mutagenesis (or in vivo somatic mutagenesis when an animal transgenic for human Ig sequences is used) so that the amino acid sequences of the VH and VL regions of the recombinant antibodies are sequences that may not naturally exist within the human antibody germline repertoire in vivo, even though the sequences are derived from and related to human germline VH and VL sequences.

[0179] The terms "subject" and "patient" are used interchangeably. As used herein, in certain embodiments, the subject is a mammal, such as a non-primate (e.g., cows, pigs, horses, cats, dogs, rats, etc.) or a primate (e.g., monkeys and humans). In specific embodiments, the subject is a human.

[0180] By "substantially all" is meant at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 98%, at least about 99%, or about 100%.

[0181] The terms "detectable agent" or "detectable molecule" are used interchangeably herein and refer to a substance that can be used to determine the presence of a desired molecule (such as an anti-SIRPα antibody as described herein) in a sample or subject. A detectable agent can be a substance that can be visualized or can be otherwise determined and / or measured (e.g., quantified).

[0182] The term "elevated" or "upregulated" when used in conjunction with SIRPα or a cytokine means that the level of SIRPα or a cytokine is higher than the normal reference range or the level of a corresponding control subject. Such "elevated" or "upregulated" SIRPα or a cytokine may be 110%, 120%, 130%, 140%, 150%, 160%, 170%, 180%, 190%, 200%, 250%, 300%, 400%, 500%, 600%, 700%, 800%, 900%, 10 times, 20 times, 30 times, 40 times, 50 times, 100 times, 200 times, 300 times, 400 times, 500 times, 600 times, 700 times, 800 times, 1000 times the SIRPα or cytokine in a control subject or a normal reference range.

[0183] The term "coding nucleic acid" or its grammatical equivalents, when used in conjunction with a nucleic acid molecule, refers to a nucleic acid molecule that, in its native state or when manipulated by methods known to those skilled in the art, can be transcribed to produce mRNA, which is then translated into a polypeptide and / or fragment thereof. The antisense strand is the complementary sequence of such a nucleic acid molecule, and the coding sequence can be inferred therefrom.

[0184] The term "excipient" refers to an inert substance that is generally used as a diluent, vehicle, preservative, binder or stabilizer, and includes, but is not limited to, proteins (e.g., serum albumin, etc.), amino acids (e.g., aspartic acid, glutamic acid, lysine, arginine, glycine, histidine, etc.), fatty acids and phospholipids (e.g., alkyl sulfonates, octanoate, etc.), surfactants (e.g., SDS, polysorbate, nonionic surfactants, etc.), sugars (e.g., sucrose, maltose, trehalose, etc.), and polyols (e.g., mannitol, sorbitol, etc.). See also Remington and Gennaro, Remington's Pharmaceutical Sciences (18th ed. 1990), which is incorporated herein by reference in its entirety.

[0185] In the case of a peptide or polypeptide, the term "fragment" as used herein refers to a peptide or polypeptide comprising an amino acid sequence that is less than the full length. Such a fragment may be derived from truncation of the amino terminus, truncation of the carboxyl terminus, and / or deletion of internal residues from the amino acid sequence. The fragment may, for example, be derived from alternative RNA splicing or in vivo protease activity. In certain embodiments, a SIRPα fragment or an anti-SIRPα antibody fragment comprises a polypeptide comprising at least 5 contiguous amino acid residues, at least 10 contiguous amino acid residues, at least 15 contiguous amino acid residues, at least 20 contiguous amino acid residues, at least 25 contiguous amino acid residues, at least 30 contiguous amino acid residues, at least 40 contiguous amino acid residues, at least 50 contiguous amino acid residues, at least 60 contiguous amino acid residues, at least 70 contiguous amino acid residues, at least 80 contiguous amino acid residues in a SIRPα polypeptide or anti-SIRPα antibody amino acid sequence. , at least 90 contiguous amino acid residues, at least 100 contiguous amino acid residues, at least 125 contiguous amino acid residues, at least 150 contiguous amino acid residues, at least 175 contiguous amino acid residues, at least 200 contiguous amino acid residues, at least 250, at least 300, at least 350, at least 400, at least 450, at least 500, at least 550, at least 600, at least 650, at least 700, at least 750, at least 800, at least 850, at least 900, or at least 950 contiguous amino acid residues. In a specific embodiment, the fragment of the SIRPα polypeptide or anti-SIRPα antibody retains at least one, at least two, at least three or more functions of the polypeptide or antibody.

[0186] The terms "about" and "approximately" mean within 20%, within 15%, within 10%, within 9%, within 8%, within 7%, within 6%, within 5%, within 4%, within 3%, within 2%, within 1% or less of a given value or range.

[0187] "Administering" or "administering" refers to the act of injecting or otherwise physically delivering a substance (e.g., an anti-SIRPα antibody as described herein) as present outside the body into a patient, such as by mucosal, intradermal, intravenous, intramuscular delivery, and / or any other physical delivery method described herein or known in the art.

[0188] In the case of solid tumors, "inhibition" can be assessed based on the inhibition of disease progression, inhibition of tumor growth, reduction of primary tumors, alleviation of tumor-related symptoms, inhibition of tumor-secreted factors, delayed appearance of primary or secondary tumors, slowing of the development of primary or secondary tumors, reduction in the incidence of primary or secondary tumors, slowing or reduction in the severity of disease side effects, tumor growth stagnation and tumor regression, increased time to progression (TTP), increased progression-free survival (PFS), increased overall survival (OS), and other factors. As used herein, OS means the time from randomization (e.g., first administration date) to death from any cause, and is measured in a treatment willingness population. As used herein, TTP means the time from randomization (e.g., first administration date) to target tumor progression; TTP does not include death. As used herein, PFS means the time from randomization (e.g., first administration date) to target tumor progression or death. In one embodiment, PFS rate is calculated using Kaplan-Meier estimates.

[0189] In certain embodiments, treatment of solid tumors can be assessed according to Response Evaluation Criteria in Solid Tumors (RECIST 1.1), see Eisenhauer EA et al., Eur J Cancer 2009; 45(2): 228-247. The assessment according to RECIST 1.1 is summarized below.

[0190] The overall response of subjects with target lesions should be assessed according to Table 7, and the overall response of subjects with only non-target lesions should be assessed according to Table 8.

[0191] Table 7: Time Point Responses: Subjects with Target (± Non-Target) Disease

[0192]

[0193]

[0194] CR = complete response, PR = partial response, SD = stable disease, PD = progressive disease, NE = not evaluable.

[0195] Table 8: Time Point Responses: Subjects with Non-Target Disease Only

[0196] Non-target lesion reactions New lesions Overall response CR no CR Non-CR / non-PD no <![CDATA[No CR / No PD a) > Not all reviews no NE Clear PD Yes or No PD any yes PD

[0197] CR = complete response, SD = stable disease, PD = progressive disease, NE = not evaluable.

[0198] a For non-target diseases, "non-CR / non-PD" is preferred rather than "stable disease"

[0199] Regarding the evaluation of target lesions, a complete response (CR) is the disappearance of all target lesions; a partial response (PR) is a decrease of at least 30% in the sum of the longest diameters of the target lesions (with the baseline sum of the longest diameters as the reference value); progressive disease (PD) is an increase of at least 20% in the sum of the longest diameters of the target lesions (with the minimum sum of the longest diameters recorded since the start of treatment or the appearance of one or more new lesions as the reference value); and stable disease (SD) is a reduction rate that is insufficient to be considered a partial response and an increase that is insufficient to be considered progressive disease (with the minimum sum of the longest diameters since the start of treatment as the reference value).

[0200] Regarding the evaluation of non-target lesions, CR is the disappearance of all non-target lesions and normalization of tumor marker levels; incomplete response / non-CR / non-PD is the persistence of one or more non-target lesions and / or maintenance of tumor marker levels above normal limits; and PD is the appearance of one or more new lesions and / or clear progression of existing non-target lesions.

[0201] Standard guidelines for responses in trials testing immunotherapeutics (Seymour et al., Lancet Oncol. 2017; 18: e143-e152) can be accessed online at: https: / / www.thelancet.com / journals / lanonc / article / PIIS1470-2045(17)30074-8

[0202] In certain embodiments, treatment of solid tumors can be assessed based on changes in Eastern Cooperative Oncology Group (ECOG) performance status (also known as ECOG PS) (Oken et al., Am J Clin Oncol. 1982; 5(6): 649-55). As used herein, ECOG PS is defined as follows.

[0203]

[0204] In certain embodiments, NHL treatment efficacy is assessed according to the "Lugano Criteria," which incorporates the International Working Group (IWG) NHL response criteria (Cheson BD et al., J Clin Oncol. 32(27): 3059-3068 (2014)) and the Deauville fluorodeoxyglucose-positron emission tomography (FDG PET) scan interpretation criteria (Itti E et al., Eur J Nucl Med Mol Imaging. 40(9): 1312-20 (2013)). As used herein, the Lugano criteria include criteria for initial assessment of site involvement and criteria for response assessment, both of which are described in further detail in the following two paragraphs.

[0205] Site involvement criteria

[0206]

[0207] CNS = central nervous system; CSF = cerebrospinal fluid; CT = computed tomography; FDG = fluorodeoxyglucose; GI = gastrointestinal; MRI = magnetic resonance imaging; PET = positron emission tomography.

[0208] a PET-CT is sufficient for confirming bone marrow involvement and can be considered highly suggestive of involvement of other extralymphatic sites. Biopsy of those sites can be considered if necessary.

[0209] Reaction Assessment Criteria

[0210]

[0211]

[0212]

[0213] 5PS = 5-point scale; CT = computed tomography; FDG = fluorodeoxyglucose; GI = gastrointestinal; IHC = immunohistochemistry; LDi = the longest cross-sectional diameter of the lesion; MRI = magnetic resonance imaging; PET = positron emission tomography; PPD = the cross product of LDi and the vertical diameter; SDi = the shortest axis perpendicular to LDi; SPD = the sum of the products of the vertical diameters of multiple lesions.

[0214] a A score of 3 in many subjects indicates a good prognosis with standard therapy, especially at interim scans. However, in trials involving PET (where studies are de-escalated), a score of 3 may be better considered an inadequate response (to avoid undertreatment).

[0215] The dominant lesions measured: up to six largest dominant nodules, nodular masses and extranodal lesions, which are selected to clearly measure with two diameters. Nodules should preferably be from the different regions of health and should include mediastinum and retroperitoneal area when applicable. Non-nodular lesions include those lesions in solid organs (such as liver, spleen, kidney and lung), GI involvement, skin lesions or those lesions recorded when palpation. Non-measured lesions: any disease that is not selected as measurable dominant disease and truly assessable disease should be considered as non-measured. These sites include being not selected as dominant or measurable or not meeting measurability requirements but still considered as abnormal any nodule, nodular mass and extranodal site, and truly assessable disease, it is any site suspected of suffering from disease, and this disease is difficult to utilize measurement to quantitatively track, including pleural effusion, ascites, bone lesions, leptomeningeal disease, abdominal mass and other lesions that cannot be confirmed and subsequently imaged. In the ring of Waldje or in extranodal sites (eg, gastrointestinal tract, liver, bone marrow), FDG uptake may be greater than in the mediastinum with a complete metabolic response but should not be higher than normal physiologic uptake in the periphery (eg, due to bone marrow activation caused by chemotherapy or myeloid growth factors).

[0216] b PET 5PS: 1, uptake not higher than background; 2, uptake < mediastinum; 3, uptake > mediastinum but < liver; 4, moderate uptake > liver; 5, uptake significantly higher than liver and / or new lesions; X, new uptake area unlikely to be related to lymphoma.

[0217] The Deauville five-point scale (5PS) is an internationally recommended scale for routine clinical use and clinical trials. It uses FDG-PET / CT for the initial staging of Hodgkin's lymphoma (HL) and certain NHL types and for the assessment of treatment response (see Itti E et al., Eur J Nucl Med Mol Imaging. 40(9):1312-20 (2013); Meignan M et al., Leuk Lymphoma. 55(1):31-7 (2014)).

[0218] The Deauville five-point scale is a simple tool for visual interpretation based on FDG absorption. It utilizes two reference points for an individual patient that have demonstrated relatively constant absorption based on serial imaging. The two reference organs are the mediastinum (also known as the blood pool) and the liver. The scale ranges from 1 to 5, with 1 being the best and 5 being the worst, as listed below. Each FDG-avid (or previously FDG-avid) lesion is rated independently.

[0219] 1. No intake or no residual intake (medium-term use)

[0220] 2. Minimal uptake, but below the blood pool (mediastinum)

[0221] 3. The uptake rate is higher than that of the mediastinum, but lower than or equal to that of the liver

[0222] 4. Uptake rate is slightly to moderately higher than that of the liver

[0223] 5. Significant increase in uptake rate or any new lesions (based on response assessment)

[0224] In some embodiments, treatment response is assessed according to the Deauville five-point scale as follows:

[0225] Complete response (CR): A score of 1, 2, or 3 and the absence of FDG-avid bone marrow lesions are interpreted as a complete metabolic response (CR), regardless of the presence of a persistent mass on CT.

[0226] Partial response (PR): A Deauville score of 4 or 5 occurs if:

[0227] - a decrease in uptake rate compared to baseline, and

[0228] - No structural progression was observed on CT.

[0229] Stable disease (SD), also known as no metabolic response: Deauville score of 4 or 5, no significant change in FDG uptake from baseline

[0230] Progressive disease (PD): Deauville score of 4 to 5, increase in intensity compared to baseline or any interim scan and / or any new FDG-avid lesions consistent with malignant lymphoma.

[0231] In the context of cancer, a "refractory" cancer (e.g., refractory NHL, refractory follicular lymphoma, or refractory DLBCL) is a cancer that has not responded to initial therapy. The term refractory cancer therefore includes cancers in which the expected effects of initial therapy are not observed. A refractory cancer can be a cancer that is getting worse or that remains the same. A "relapsed" cancer (e.g., relapsed NHL, relapsed follicular lymphoma, or relapsed DLBCL) is a cancer that responded to therapy, e.g., stopped progressing, progressed more slowly than without treatment, regressed, or even largely or completely disappeared, but then stopped responding or returned.

[0232] In the context of polypeptides, as used herein, the term "analog" refers to a polypeptide that has a similar or identical function to a SIRPα polypeptide, a SIRPα polypeptide fragment, or an anti-SIRPα antibody, but does not necessarily contain a similar or identical amino acid sequence to a SIRPα polypeptide, a SIRPα polypeptide fragment, or an anti-SIRPα antibody, or has a similar or identical structure to a SIRPα polypeptide, a SIRPα polypeptide fragment, or an anti-SIRPα antibody. A polypeptide having a similar amino acid sequence refers to a polypeptide that satisfies at least one of the following: (a) an amino acid sequence that is at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% or at least 99% identical to the amino acid sequence of a SIRPα polypeptide, a SIRPα polypeptide fragment, or an anti-SIRPα antibody described herein; (b) a polypeptide that is derived from a polypeptide encoding a SIRPα polypeptide, a SIRPα polypeptide fragment, or an anti-SIRPα antibody described herein under stringent conditions. or its VH or VL region) and has at least 5 amino acid residues, at least 10 amino acid residues, at least 15 amino acid residues, at least 20 amino acid residues, at least 25 amino acid residues, at least 30 amino acid residues, at least 40 amino acid residues, at least 50 amino acid residues, at least 60 amino acid residues, at least 70 amino acid residues, at least 80 amino acid residues, at least 90 amino acid residues, at least 100 amino acid residues, at least 125 amino acid residues, or at least 150 amino acid residues (see, e.g., Sambrook et al., Molecular Cloning:A Laboratory Manual (2001); and Maniatis et al., Molecular Cloning:A Laboratory Manual (1982)); or (c) a polypeptide encoded by a nucleotide sequence that is at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% or at least 99% identical to a nucleotide sequence encoding a SIRPα polypeptide, SIRPα polypeptide fragment or anti-SIRPα antibody (or its VH or VL region) described herein. A polypeptide having a similar structure to a SIRPα polypeptide, SIRPα polypeptide fragment or anti-SIRPα antibody described herein refers to a polypeptide having a similar secondary, tertiary or quaternary structure to a SIRPα polypeptide, SIRPα polypeptide fragment or anti-SIRPα antibody described herein. The structure of a polypeptide can be determined by methods known to those skilled in the art, including but not limited to X-ray crystallography, nuclear magnetic resonance and crystal electron microscopy.

[0233] In the context of polypeptides, as used herein, the term "derivative" refers to a polypeptide comprising the amino acid sequence of a SIRPα polypeptide, a SIRPα polypeptide fragment, or an antibody that binds to a SIRPα polypeptide, which has been altered by the introduction of amino acid residue substitutions, deletions, or additions. As used herein, the term "derivative" also refers to a SIRPα polypeptide, a SIRPα polypeptide fragment, or an antibody that binds to a SIRPα polypeptide, which has been chemically modified, for example, by covalently attaching any type of molecule to the polypeptide. For example, but not limitation, a SIRPα polypeptide, a SIRPα polypeptide fragment, or an anti-SIRPα antibody may be chemically modified, for example, by glycosylation, acetylation, pegylation, phosphorylation, amidation, derivatization by known protecting / blocking groups, proteolytic cleavage, chemical cleavage, formulation, tunicamycin metabolic synthesis, attachment to a cellular ligand or other protein, and the like. A derivative is modified in a manner that is different from the naturally occurring or starting peptide or polypeptide (in terms of the type or position of the molecule to which it is attached). Derivatives further include the absence of one or more chemical groups naturally occurring on the peptide or polypeptide. In addition, derivatives of SIRPα polypeptides, SIRPα polypeptide fragments, or anti-SIRPα antibodies may contain one or more non-classical amino acids. The polypeptide derivatives have similar or identical functions to the SIRPα polypeptides, SIRPα polypeptide fragments, or anti-SIRPα antibodies described herein.

[0234] The term "composition" is intended to encompass a product containing the specified ingredients (eg, an antibody provided herein), optionally in the specified amounts.

[0235] 4.3 Composition and preparation method thereof

[0236] Provided herein are antibodies that bind to a SIRPα polypeptide, a SIRPα polypeptide fragment, a SIRPα peptide, or a SIRPα epitope.

[0237] In certain embodiments, the antibodies provided herein bind to human and / or cynomolgus monkey SIRPα. In one embodiment, the SIRPα antibody binds to human SIRPα. In one embodiment, the SIRPα antibody binds to cynomolgus monkey SIRPα. In one embodiment, the SIRPα antibody binds to human SIRPα and cynomolgus monkey SIRPα. In other embodiments, the antibodies provided herein do not bind to rodent SIRPα.

[0238] In some embodiments, the anti-SIRPα antibody binds to the extracellular domain (ECD) of SIRPα. In certain embodiments, the anti-SIRPα antibody binds to an epitope in the ECD of SIRPα that overlaps with the CD47 binding site. In certain embodiments, the anti-SIRPα antibody binds to an epitope in the ECD of SIRPα that is identical to the CD47 binding site.

[0239] Also provided are antibodies that competitively block the binding of an anti-SIRPα antibody provided herein to a SIRPα polypeptide.

[0240] Also provided are antibodies that compete with the anti-SIRPα antibodies provided herein for binding to a SIRPα polypeptide.

[0241] In some embodiments, the anti-SIRPα antibody blocks the binding of CD47 to the SIRPα polypeptide. In some embodiments, the anti-SIRPα antibody competes for the binding of CD47 to the SIRPα polypeptide.

[0242] In certain embodiments, the antibodies provided herein inhibit the binding of CD47 to SIRPα. In other embodiments, the antibodies provided herein block the binding of CD47 to SIRPα.

[0243] The anti-SIRPα antibodies provided herein can also be conjugated or recombinantly fused to, for example, a detectable agent. Compositions comprising anti-SIRPα antibodies are further provided.

[0244] Also provided herein are isolated nucleic acid molecules encoding an immunoglobulin heavy chain, light chain, VH region, VL region, VH CDR1, VH CDR2, VHCDR3, VL CDR1, VL CDR2, and / or VL CDR3 of an anti-SIRPα antibody that binds to a SIRPα polypeptide, SIRPα polypeptide fragment, SIRPα peptide, or SIRPα epitope.

[0245] Further provided are vectors and host cells comprising nucleic acid molecules encoding anti-SIRPα antibodies that bind to a SIRPα polypeptide, a SIRPα polypeptide fragment, a SIRPα peptide, or a SIRPα epitope. Also provided are methods for preparing antibodies that bind to a SIRPα polypeptide, a SIRPα polypeptide fragment, a SIRPα peptide, or a SIRPα epitope.

[0246] 4.3.1 Anti-SIRPα Antibodies

[0247] In one embodiment, the present disclosure provides anti-SIRPα antibodies useful as therapeutic agents herein. Exemplary antibodies include polyclonal antibodies, monoclonal antibodies, humanized antibodies, human antibodies, bispecific antibodies, and heteroconjugate antibodies, as well as variants thereof with improved affinity or other properties.

[0248] In some embodiments, antibodies are provided herein that bind to SIRPα (including SIRPα polypeptides, SIRPα polypeptide fragments, SIRPα peptides, or SIRPα epitopes). In certain embodiments, the antibodies provided herein bind to human and / or cynomolgus monkey SIRPα. In other embodiments, the antibodies provided herein do not bind to rodent SIRPα (e.g., mouse SIRPα). In one embodiment, the antibodies provided herein bind to human SIRPα. In another embodiment, the antibodies provided herein bind to cynomolgus monkey SIRPα. In another embodiment, the antibodies provided herein bind to human SIRPα and cynomolgus monkey SIRPα. In some embodiments, the antibodies provided herein bind to human SIRPα and do not bind to rodent SIRPα (e.g., mouse SIRPα). In some embodiments, the antibodies provided herein bind to cynomolgus monkey SIRPα and do not bind to rodent SIRPα (e.g., mouse SIRPα). In some embodiments, the antibodies provided herein bind to human SIRPα, bind to cynomolgus monkey SIRPα, and do not bind to rodent SIRPα (e.g., mouse SIRPα). In some embodiments, the anti-SIRPα antibody blocks or inhibits CD47 binding to the SIRPα polypeptide. In some embodiments, the anti-SIRPα antibody competes with CD47 for binding to the SIRPα polypeptide. In other embodiments, the anti-SIRPα antibody is a human or humanized antibody (e.g., comprising a human constant region) that binds to SIRPα (including a SIRPα polypeptide, a SIRPα polypeptide fragment, a SIRPα peptide, or a SIRPα epitope).

[0249] In certain embodiments, the anti-SIRPα antibody comprises the VH region, VL region, VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2 and / or VL CDR3 of any one of the monoclonal antibodies described herein, such as the amino acid sequences depicted in Tables 1-4 and 9-10. Thus, in some embodiments, the isolated antibodies or functional fragments thereof provided herein comprise one, two and / or three heavy chain CDRs and / or one, two and / or three light chain CDRs from: (a) antibody SIRPAB-1, (b) antibody SIRPAB-2, (c) antibody SIRPAB-3, (d) antibody SIRPAB-4, (e) antibody SIRPAB-5, (f) antibody SIRPAB-6, (g) antibody SIRPAB-7, (h) antibody SIRPAB-8, (i) antibody SIRPAB-9, (j) antibody SIRPAB-10, (k) antibody SIRPAB-11, (l) antibody SIRPAB-12, (m) antibody SIRPAB-13, (n) antibody SIRPAB-17, (o) antibody SIRPAB-18, (p) antibody SIRPAB-19, (q) antibody SIRPAB-20, or (r) antibody SIRPAB-21, as shown in Tables 1-2.

[0250] Table 1. VL CDR amino acid sequences

[0251]

[0252] Table 2. VH CDR amino acid sequences

[0253]

[0254]

[0255] In some embodiments, the antibodies provided herein comprise or consist of six CDRs, e.g., VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and / or VL CDR3 identified in Tables 1-2. In some embodiments, the antibodies provided herein may comprise less than six CDRs. In some embodiments, the antibodies comprise or consist of one, two, three, four, or five CDRs selected from the group consisting of: VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and / or VL CDR3 identified in Tables 1-2. In some embodiments, the antibodies comprise or consist of one, two, three, four, or five CDRs selected from the group consisting of: VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and / or VL CDR3 of a monoclonal antibody. The monoclonal antibody is selected from the group consisting of: (a) antibody SIRPAB-1, (b) antibody SIRPAB-2, (c) antibody SIRPAB-3, (d) antibody SIRPAB-4, (e) antibody SIRPAB-5, (f) antibody SIRPAB-6, (g) antibody SIRPAB-7, (h) antibody SIRPAB-8, (i) antibody SIRPAB-9, (j) antibody SIRPAB-10, (k) antibody SIRPAB-11, (l) antibody SIRPAB-12, (m) antibody SIRPAB-13, (n) antibody SIRPAB-17, (o) antibody SIRPAB-18, (p) antibody SIRPAB-19, (q) antibody SIRPAB-20, and (r) antibody SIRPAB-21 described herein. Thus, in some embodiments, the antibody comprises or consists of one, two, three, four, or five CDRs of any of the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and / or VL CDR3 identified in Tables 1-2.

[0256] In some embodiments, the antibodies provided herein comprise one or more (e.g., one, two, or three) VH CDRs listed in Table 2. In other embodiments, the antibodies provided herein comprise one or more (e.g., one, two, or three) VL CDRs listed in Table 1. In yet other embodiments, the antibodies provided herein comprise one or more (e.g., one, two, or three) VH CDRs listed in Table 2 and one or more VL CDRs listed in Table 1. Thus, in some embodiments, the antibodies comprise a VH CDR1 having an amino acid sequence of any one of SEQ ID NOs: 78 and 82. In some embodiments, the antibodies comprise a VH CDR2 having an amino acid sequence of any one of SEQ ID NOs: 69 and 83. In some embodiments, the antibodies comprise a VH CDR3 having an amino acid sequence of SEQ ID NO: 57. In some embodiments, the antibodies comprise a VH CDR1 and / or a VH CDR2 and / or a VH CDR3 independently selected from any one of the VH CDR1, VH CDR2, and VH CDR3 amino acid sequences as depicted in Table 2. In some embodiments, the antibody comprises a VL CDR1 having the amino acid sequence of SEQ ID NO: 62. In another embodiment, the antibody comprises a VL CDR2 having the amino acid sequence of SEQ ID NO: 63. In some embodiments, the antibody comprises a VL CDR3 having the amino acid sequence of SEQ ID NO: 65. In some embodiments, the antibody comprises a VL CDR1 and / or a VL CDR2 and / or a VL CDR3 independently selected from any one of the VL CDR1, VL CDR2, and VL CDR3 amino acid sequences depicted in Table 1.

[0257] In certain embodiments, the antibodies provided herein comprise a VH region comprising: (1) a VH CDR1 having the amino acid sequence of SEQ ID NO: 78, (2) a VH CDR2 having the amino acid sequence of SEQ ID NO: 69, and (3) a VH CDR3 having the amino acid sequence of SEQ ID NO: 57; and a VL region comprising: (1) a VL CDR1 having the amino acid sequence of SEQ ID NO: 62; (2) a VL CDR2 having the amino acid sequence of SEQ ID NO: 63; and (3) a VLCDR3 having the amino acid sequence of SEQ ID NO: 65.

[0258] In certain embodiments, the antibodies provided herein comprise a VH region comprising: (1) a VH CDR1 having the amino acid sequence of SEQ ID NO: 82, (2) a VH CDR2 having the amino acid sequence of SEQ ID NO: 83, and (3) a VH CDR3 having the amino acid sequence of SEQ ID NO: 57; and a VL region comprising: (1) a VL CDR1 having the amino acid sequence of SEQ ID NO: 62, (2) a VL CDR2 having the amino acid sequence of SEQ ID NO: 63, and (3) a VL CDR3 having the amino acid sequence of SEQ ID NO: 65.

[0259] In some embodiments, the antibodies provided herein comprise a VH region comprising: (1) a VH CDR1 having the amino acid sequence of SEQ ID NO: 78; (2) a VH CDR2 having the amino acid sequence of SEQ ID NO: 69; and (3) a VH CDR3 having the amino acid sequence of SEQ ID NO: 57.

[0260] In other embodiments, the antibodies provided herein comprise a VL region comprising: (1) a VL CDR1 having the amino acid sequence of SEQ ID NO: 62; (2) a VL CDR2 having the amino acid sequence of SEQ ID NO: 63; and (3) a VL CDR3 having the amino acid sequence of SEQ ID NO: 65.

[0261] In some embodiments, the antibodies provided herein comprise a VH region comprising: (1) a VH CDR1 having the amino acid sequence of SEQ ID NO: 82; (2) a VH CDR2 having the amino acid sequence of SEQ ID NO: 83; and (3) a VH CDR3 having the amino acid sequence of SEQ ID NO: 57.

[0262] Also provided herein are antibodies comprising one or more (e.g., one, two, or three) VH CDRs and one or more (e.g., one, two, or three) VL CDRs listed in Tables 1-2. Specifically, provided herein are antibodies comprising VH CDR1 (SEQ ID NO: 78 or 82) and VL CDR1 (SEQ ID NO: 62). In one embodiment, the antibody comprises VH CDR1 (SEQ ID NO: 78 or 82) and VL CDR2 (SEQ ID NO: 63). In other embodiments, the antibody comprises VH CDR1 (SEQ ID NO: 78 or 82) and VL CDR3 (SEQ ID NO: 65). In another embodiment, the antibody comprises VH CDR2 (SEQ ID NO: 69 or 83) and VL CDR1 (SEQ ID NO: 62). In some embodiments, the antibody comprises VH CDR2 (SEQ ID NO: 69 or 83) and VL CDR2 (SEQ ID NO: 63). In one embodiment, the antibody comprises a VH CDR2 (SEQ ID NO: 69 or 83) and a VL CDR3 (SEQ ID NO: 65). In another embodiment, the antibody comprises a VH CDR3 (SEQ ID NO: 57) and a VL CDR1 (SEQ ID NO: 62). In other embodiments, the antibody comprises a VH CDR3 (SEQ ID NO: 57) and a VL CDR2 (SEQ ID NO: 63). In some embodiments, the antibody comprises a VH CDR3 (SEQ ID NO: 57) and a VL CDR3 (SEQ ID NO: 65). In another embodiment, the antibody comprises a VH CDR1 (SEQ ID NO: 78 or 82), a VH CDR2 (SEQ ID NO: 69 or 83), and a VL CDR1 (SEQ ID NO: 62). In one embodiment, the antibody comprises a VH CDR1 (SEQ ID NO: 78 or 82), a VH CDR2 (SEQ ID NO: 69 or 83), and a VL CDR2 (SEQ ID NO: 63). In other embodiments, the antibody comprises a VH CDR1 (SEQ ID NO: 78 or 82), a VH CDR2 (SEQ ID NO: 69 or 83), and a VL CDR3 (SEQ ID NO: 65). In another embodiment, the antibody comprises a VH CDR2 (SEQ ID NO: 69 or 83), a VH CDR3 (SEQ ID NO: 57), and a VL CDR1 (SEQ ID NO: 62).In some embodiments, the antibody comprises VH CDR2 (SEQ ID NO: 69 or 83), VH CDR3 (SEQ ID NO: 57), and VL CDR2 (SEQ ID NO: 63). In one embodiment, the antibody comprises VH CDR2 (SEQ ID NO: 69 or 83), VH CDR3 (SEQ ID NO: 57), and VL CDR3 (SEQ ID NO: 65). In another embodiment, the antibody comprises VH CDR1 (SEQ ID NO: 78 or 82), VH CDR3 (SEQ ID NO: 57), and VL CDR1 (SEQ ID NO: 62). In other embodiments, the antibody comprises VH CDR1 (SEQ ID NO: 78 or 82), VH CDR3 (SEQ ID NO: 57), and VL CDR2 (SEQ ID NO: 63). In some embodiments, the antibody comprises VH CDR1 (SEQ ID NO: 78 or 82), VH CDR3 (SEQ ID NO: 57), and VL CDR3 (SEQ ID NO: 65). In another embodiment, the antibody comprises VH CDR1 (SEQ ID NO: 78 or 82), VL CDR1 (SEQ ID NO: 62), and VL CDR2 (SEQ ID NO: 63). In one embodiment, the antibody comprises VH CDR1 (SEQ ID NO: 78 or 82), VL CDR1 (SEQ ID NO: 62), and VL CDR3 (SEQ ID NO: 65). In other embodiments, the antibody comprises VH CDR1 (SEQ ID NO: 78 or 82), VL CDR2 (SEQ ID NO: 63), and VL CDR3 (SEQ ID NO: 65). In another embodiment, the antibody comprises VH CDR2 (SEQ ID NO: 69 or 83), VL CDR1 (SEQ ID NO: 62), and VL CDR2 (SEQ ID NO: 63). In some embodiments, the antibody comprises VH CDR2 (SEQ ID NO: 69 or 83), VL CDR1 (SEQ ID NO: 62), and VL CDR3 (SEQ ID NO: 65). In one embodiment, the antibody comprises VH CDR2 (SEQ ID NO: 69 or 83), VL CDR2 (SEQ ID NO: 63) and VL CDR3 (SEQ ID NO: 65). In another embodiment, the antibody comprises VH CDR3 (SEQ ID NO: 57), VL CDR1 (SEQ ID NO: 62) and VL CDR2 (SEQ ID NO: 63).In other embodiments, the antibody comprises a VH CDR3 (SEQ ID NO: 57), a VL CDR1 (SEQ ID NO: 62), and a VL CDR3 (SEQ ID NO: 65). In some embodiments, the antibody comprises a VH CDR3 (SEQ ID NO: 57), a VL CDR2 (SEQ ID NO: 63), and a VL CDR3 (SEQ ID NO: 65). In another embodiment, the antibody comprises a VH CDR1 (SEQ ID NO: 78 or 82), a VH CDR2 (SEQ ID NO: 69 or 83), a VH CDR3 (SEQ ID NO: 57), and a VL CDR1 (SEQ ID NO: 62). In one embodiment, the antibody comprises a VH CDR1 (SEQ ID NO: 78 or 82), a VH CDR2 (SEQ ID NO: 69 or 83), a VH CDR3 (SEQ ID NO: 57), and a VL CDR2 (SEQ ID NO: 63). In other embodiments, the antibody comprises VH CDR1 (SEQ ID NO: 78 or 82), VH CDR2 (SEQ ID NO: 69 or 83), VH CDR3 (SEQ ID NO: 57) and VL CDR3 (SEQ ID NO: 65). In another embodiment, the antibody comprises VH CDR1 (SEQ ID NO: 78 or 82), VH CDR2 (SEQ ID NO: 69 or 83), VL CDR1 (SEQ ID NO: 62) and VL CDR2 (SEQ ID NO: 63). In some embodiments, the antibody comprises VH CDR1 (SEQ ID NO: 78 or 82), VH CDR2 (SEQ ID NO: 69 or 83), VL CDR1 (SEQ ID NO: 62) and VL CDR3 (SEQ ID NO: 65). In one embodiment, the antibody comprises VH CDR1 (SEQ ID NO: 78 or 82), VH CDR2 (SEQ ID NO: 69 or 83), VL CDR2 (SEQ ID NO: 63) and VL CDR3 (SEQ ID NO: 65). In another embodiment, the antibody comprises VH CDR1 (SEQ ID NO: 78 or 82), VH CDR3 (SEQ ID NO: 57), VL CDR1 (SEQ ID NO: 62) and VL CDR2 (SEQ ID NO: 63).In other embodiments, the antibody comprises a VH CDR1 (SEQ ID NO: 78 or 82), a VH CDR3 (SEQ ID NO: 57), a VL CDR1 (SEQ ID NO: 62), and a VL CDR3 (SEQ ID NO: 65). In some embodiments, the antibody comprises a VH CDR1 (SEQ ID NO: 78 or 82), a VH CDR3 (SEQ ID NO: 57), a VL CDR2 (SEQ ID NO: 63), and a VL CDR3 (SEQ ID NO: 65). In another embodiment, the antibody comprises a VH CDR2 (SEQ ID NO: 69 or 83), a VH CDR3 (SEQ ID NO: 57), a VL CDR1 (SEQ ID NO: 62), and a VL CDR2 (SEQ ID NO: 63). In one embodiment, the antibody comprises a VH CDR2 (SEQ ID NO: 69 or 83), a VH CDR3 (SEQ ID NO: 57), a VL CDR1 (SEQ ID NO: 62), and a VL CDR3 (SEQ ID NO: 65). In another embodiment, the antibody comprises a VH CDR2 (SEQ ID NO: 69 or 83), a VH CDR3 (SEQ ID NO: 57), a VL CDR2 (SEQ ID NO: 63), and a VL CDR3 (SEQ ID NO: 65). In another embodiment, the antibody comprises a VH CDR1 (SEQ ID NO: 78 or 82), a VH CDR2 (SEQ ID NO: 69 or 83), a VH CDR3 (SEQ ID NO: 57), a VL CDR1 (SEQ ID NO: 62), and a VL CDR2 (SEQ ID NO: 63). In some embodiments, the antibody comprises VH CDR1 (SEQ ID NO: 78 or 82), VH CDR2 (SEQ ID NO: 69 or 83), VH CDR3 (SEQ ID NO: 57), VL CDR1 (SEQ ID NO: 62), and VL CDR3 (SEQ ID NO: 65). In one embodiment, the antibody comprises VH CDR1 (SEQ ID NO: 78 or 82), VH CDR2 (SEQ ID NO: 69 or 83), VHCDR3 (SEQ ID NO: 57), VL CDR2 (SEQ ID NO: 63), and VL CDR3 (SEQ ID NO: 65).In another embodiment, the antibody comprises a VH CDR1 (SEQ ID NO: 78 or 82), a VH CDR2 (SEQ ID NO: 69 or 83), a VL CDR1 (SEQ ID NO: 62), a VL CDR2 (SEQ ID NO: 63), and a VL CDR3 (SEQ ID NO: 65). In other embodiments, the antibody comprises a VH CDR1 (SEQ ID NO: 78 or 82), a VH CDR3 (SEQ ID NO: 57), a VL CDR1 (SEQ ID NO: 62), a VL CDR2 (SEQ ID NO: 63), and a VL CDR3 (SEQ ID NO: 65). In some embodiments, the antibody comprises a VH CDR2 (SEQ ID NO: 69 or 83), a VH CDR3 (SEQ ID NO: 57), a VL CDR1 (SEQ ID NO: 62), a VL CDR2 (SEQ ID NO: 63), and a VL CDR3 (SEQ ID NO: 65). In another embodiment, the antibody comprises a VH CDR1 (SEQ ID NO: 78 or 82), a VL CDR1 (SEQ ID NO: 62), a VL CDR2 (SEQ ID NO: 63), and a VL CDR3 (SEQ ID NO: 65). In one embodiment, the antibody comprises a VH CDR2 (SEQ ID NO: 69 or 83), a VL CDR1 (SEQ ID NO: 62), a VL CDR2 (SEQ ID NO: 63), and a VL CDR3 (SEQ ID NO: 65). In other embodiments, the antibody comprises a VH CDR3 (SEQ ID NO: 57), a VL CDR1 (SEQ ID NO: 62), a VL CDR2 (SEQ ID NO: 63), and a VL CDR3 (SEQ ID NO: 65). In another embodiment, the antibody comprises any combination of the VH CDRs and VL CDRs listed in Tables 1-2.

[0263] In yet another aspect, CDR disclosed herein comprises a consensus sequence derived from a group of related antibodies (see, e.g., Tables 1-2). As described herein, a "consensus sequence" refers to an amino acid sequence having conserved amino acids common to many sequences and variable amino acids that are different within a given amino acid sequence.

[0264] In some embodiments, the isolated antibodies or functional fragments thereof provided herein further comprise one, two, three and / or four heavy chain FRs and / or one, two, three and / or four light chain FRs from: (a) antibody SIRPAB-1, (b) antibody SIRPAB-2, (c) antibody SIRPAB-3, (d) antibody SIRPAB-4, (e) antibody SIRPAB-5, (f) antibody SIRPAB-6, (g) antibody SIRPAB-7, (h) antibody SIRPAB-8, (i) antibody SIRPAB-9, (j) antibody SIRPAB-10, (k) antibody SIRPAB-11, (l) antibody SIRPAB-12, (m) antibody SIRPAB-13, (n) antibody SIRPAB-17, (o) antibody SIRPAB-18, (p) antibody SIRPAB-19, (q) antibody SIRPAB-20, and (r) antibody SIRPAB-21, as shown in Tables 3-4.

[0265] Table 3. VL FR amino acid sequences

[0266]

[0267]

[0268] Table 4. VH FR amino acid sequences

[0269]

[0270]

[0271] In certain embodiments, the isolated antibodies or functional fragments thereof provided herein further comprise one, two, three and / or four heavy chains from (a) antibody SIRPAB-1, (b) antibody SIRPAB-2, (c) antibody SIRPAB-3, (d) antibody SIRPAB-4, (e) antibody SIRPAB-5, (f) antibody SIRPAB-6, (g) antibody SIRPAB-7, (h) antibody SIRPAB-8, (i) antibody SIRPAB-9, (j) antibody SIRPAB-10, (k) antibody SIRPAB-11, (l) antibody SIRPAB-12, (m) antibody SIRPAB-13, (n) antibody SIRPAB-17, (o) antibody SIRPAB-18, (p) antibody SIRPAB-19, (q) antibody SIRPAB-20, and (r) antibody SIRPAB-21, as shown in Table 4. In some embodiments, the antibody heavy chain FR is from antibody SIRPAB-1. In some embodiments, the antibody heavy chain FRs are from the antibody SIRPAB-2. In other embodiments, the antibody heavy chain FRs are from the antibody SIRPAB-3. In certain embodiments, the antibody heavy chain FRs are from the antibody SIRPAB-4. In other embodiments, the antibody heavy chain FRs are from the antibody SIRPAB-5. In some embodiments, the antibody heavy chain FRs are from the antibody SIRPAB-6. In some embodiments, the antibody heavy chain FRs are from the antibody SIRPAB-7. In some embodiments, the antibody heavy chain FRs are from the antibody SIRPAB-8. In certain embodiments, the antibody heavy chain FRs are from the antibody SIRPAB-9. In some embodiments, the antibody heavy chain FRs are from the antibody SIRPAB-10. In some embodiments, the antibody heavy chain FRs are from the antibody SIRPAB-11. In certain embodiments, the antibody heavy chain FRs are from the antibody SIRPAB-12. In some embodiments, the antibody heavy chain FRs are from the antibody SIRPAB-13. In some embodiments, the antibody heavy chain FRs are from the antibody SIRPAB-17. In certain embodiments, the antibody heavy chain FRs are from the antibody SIRPAB-18. In some embodiments, the antibody heavy chain FR is from the antibody SIRPAB-19. In certain embodiments, the antibody heavy chain FR is from the antibody SIRPAB-20. In another embodiment, the antibody heavy chain FR is from the antibody SIRPAB-21.

[0272] In some embodiments, the isolated antibodies or functional fragments thereof provided herein further comprise one, two, three and / or four light chains from (a) antibody SIRPAB-1, (b) antibody SIRPAB-2, (c) antibody SIRPAB-3, (d) antibody SIRPAB-4, (e) antibody SIRPAB-5, (f) antibody SIRPAB-6, (g) antibody SIRPAB-7, (h) antibody SIRPAB-8, (i) antibody SIRPAB-9, (j) antibody SIRPAB-10, (k) antibody SIRPAB-11, (l) antibody SIRPAB-12, (m) antibody SIRPAB-13, (n) antibody SIRPAB-17, (o) antibody SIRPAB-18, (p) antibody SIRPAB-19, (q) antibody SIRPAB-20, and (r) antibody SIRPAB-21, as shown in Table 3. In some embodiments, the antibody light chain FR is from antibody SIRPAB-1. In some embodiments, the antibody light chain FRs are from the antibody SIRPAB-2. In other embodiments, the antibody light chain FRs are from the antibody SIRPAB-3. In certain embodiments, the antibody light chain FRs are from the antibody SIRPAB-4. In other embodiments, the antibody light chain FRs are from the antibody SIRPAB-5. In some embodiments, the antibody light chain FRs are from the antibody SIRPAB-6. In some embodiments, the antibody light chain FRs are from the antibody SIRPAB-7. In some embodiments, the antibody light chain FRs are from the antibody SIRPAB-8. In included embodiments, the antibody light chain FRs are from the antibody SIRPAB-9. In some embodiments, the antibody light chain FRs are from the antibody SIRPAB-10. In some embodiments, the antibody light chain FRs are from the antibody SIRPAB-11. In certain embodiments, the antibody light chain FRs are from the antibody SIRPAB-12. In some embodiments, the antibody light chain FRs are from the antibody SIRPAB-13. In some embodiments, the antibody light chain FRs are from the antibody SIRPAB-17. In certain embodiments, the antibody light chain FRs are from the antibody SIRPAB-18. In some embodiments, the antibody light chain FR is from the antibody SIRPAB-19. In certain embodiments, the antibody light chain FR is from the antibody SIRPAB-20. In another embodiment, the antibody light chain FR is from the antibody SIRPAB-21.

[0273] In certain embodiments, the antibodies or fragments thereof described herein comprise a VH region comprising: (1) a VH FR1 having the amino acid sequence of SEQ ID NO: 52; (2) a VH FR2 having the amino acid sequence of SEQ ID NO: 54; (3) a VH FR3 having the amino acid sequence of SEQ ID NO: 56; and / or (4) a VH FR4 having the amino acid sequence of SEQ ID NO: 58. In specific embodiments, the antibodies comprise a VH region comprising all four of the above-mentioned VH FR1, VH FR2, VH FR3, and VH FR4.

[0274] Thus, in some embodiments, the humanized antibody comprises a VH region comprising a VHFR1 having an amino acid sequence of SEQ ID NO: 52. In some embodiments, the humanized antibody comprises a VH region comprising a VH FR2 having an amino acid sequence of SEQ ID NO: 54. In some embodiments, the humanized antibody comprises a VH region comprising a VH FR3 having an amino acid sequence of SEQ ID NO: 56. In other embodiments, the humanized antibody comprises a VH region comprising a VH FR4 having an amino acid sequence of SEQ ID NO: 58.

[0275] In certain embodiments, the antibodies or antigen-binding fragments thereof described herein comprise a VL region comprising: (1) a VL FR1 having the amino acid sequence of SEQ ID NO:61; (2) a VL FR2 having the amino acid sequence of SEQ ID NO:12; (3) a VL FR3 having the amino acid sequence of SEQ ID NO:64; and / or (4) a VL FR4 having the amino acid sequence of SEQ ID NO:16.

[0276] Thus, in some embodiments, the humanized antibody comprises a VL region comprising a VLFR1 having an amino acid sequence of SEQ ID NO: 61. In certain embodiments, the humanized antibody comprises a VL region comprising a VL FR2 having an amino acid sequence of SEQ ID NO: 12. In other embodiments, the humanized antibody comprises a VL region comprising a VL FR3 having an amino acid sequence of SEQ ID NO: 64. In yet other embodiments, the humanized antibody comprises a VL region comprising a VL FR4 having an amino acid sequence of SEQ ID NO: 16.

[0277] In certain embodiments, the antibodies or antigen-binding fragments thereof described herein comprise a VH region and a VL region, wherein the VH region comprises: (1) a VH FR1 having an amino acid sequence of SEQ ID NO: 52; (2) a VH FR2 having an amino acid sequence of SEQ ID NO: 54; (3) a VH FR3 having an amino acid sequence of SEQ ID NO: 56; and / or (4) a VH FR4 having an amino acid sequence of SEQ ID NO: 58; and wherein the VL region comprises: (1) a VL FR1 having an amino acid sequence of SEQ ID NO: 61; (2) a VL FR2 having an amino acid sequence of SEQ ID NO: 12; (3) a VL FR3 having an amino acid sequence of SEQ ID NO: 64; and / or (4) a VL FR4 having an amino acid sequence of SEQ ID NO: 16. In some embodiments, the antibodies comprise a VH region comprising all four of the above-mentioned VH FR1, VH FR2, VH FR3, and VH FR4. In other embodiments, the antibody comprises a VL region comprising all four of the above-mentioned VL FR1, VL FR2, VL FR3, and VL FR4. In yet other embodiments, the antibody comprises a VH region comprising all four of the above-mentioned VH FR1, VH FR2, VH FR3, and VH FR4, and a VL region comprising all four of the above-mentioned VL FR1, VL FR2, VL FR3, and VL FR4.

[0278] Also provided herein are antibodies comprising one or more (e.g., one, two, three, or four) VH FRs and one or more (e.g., one, two, three, or four) VL FRs listed in Tables 3-4. Specifically, provided herein is an antibody comprising VH FR1 (SEQ ID NO: 52) and VL FR1 (SEQ ID NO: 61). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52) and VL FR2 (SEQ ID NO: 12). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52) and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52) and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54) and VL FR1 (SEQ ID NO: 61). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54) and VL FR2 (SEQ ID NO: 12). In some embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54) and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54) and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR3 (SEQ ID NO: 56) and VL FR1 (SEQ ID NO: 61). In other embodiments, the antibody comprises VH FR3 (SEQ ID NO: 56) and VL FR2 (SEQ ID NO: 12). In another embodiment, the antibody comprises VH FR3 (SEQ ID NO: 56) and VL FR3 (SEQ ID NO: 64). In some embodiments, the antibody comprises VH FR3 (SEQ ID NO: 56) and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR4 (SEQ ID NO: 58) and VL FR1 (SEQ ID NO: 61). In another embodiment, the antibody comprises VH FR4 (SEQ ID NO: 58) and VL FR2 (SEQ ID NO: 12). In one embodiment, the antibody comprises VH FR4 (SEQ ID NO: 58) and VL FR3 (SEQ ID NO: 64). In some embodiments, the antibody comprises VH FR4 (SEQ ID NO: 58) and VL FR4 (SEQ ID NO: 16).In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), and VL FR1 (SEQ ID NO: 61). In other embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), and VL FR2 (SEQ ID NO: 12). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), and VL FR1 (SEQ ID NO: 61). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), and VL FR2 (SEQ ID NO: 12). In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), and VL FR3 (SEQ ID NO: 64). In other embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VL FR1 (SEQ ID NO: 61), and VL FR2 (SEQ ID NO: 12). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VL FR1 (SEQ ID NO: 61), and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VL FR1 (SEQ ID NO: 61), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16).In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VL FR1 (SEQ ID NO: 61), and VL FR2 (SEQ ID NO: 12). In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VL FR1 (SEQ ID NO: 61), and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VL FR1 (SEQ ID NO: 61), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), and VL FR2 (SEQ ID NO: 12). In other embodiments, the antibody comprises VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), and VL FR3 (SEQ ID NO: 64). In some embodiments, the antibody comprises VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR3 (SEQ ID NO: 56), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR3 (SEQ ID NO: 56), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR3 (SEQ ID NO: 56), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16).In another embodiment, the antibody comprises VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR2 (SEQ ID NO: 12). In some embodiments, the antibody comprises VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR3 (SEQ ID NO: 64). In other embodiments, the antibody comprises VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR4 (SEQ ID NO: 58), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), and VL FR1 (SEQ ID NO: 61). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), and VL FR2 (SEQ ID NO: 12). In other embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), and VL FR1 (SEQ ID NO: 61).In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), and VL FR2 (SEQ ID NO: 12). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), and VL FR1 (SEQ ID NO: 61). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), and VL FR2 (SEQ ID NO: 12). In other embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), and VL FR1 (SEQ ID NO: 61). In some embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), and VL FR2 (SEQ ID NO: 12). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), and VL FR3 (SEQ ID NO: 64).In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VL FR1 (SEQ ID NO: 61), and VL FR2 (SEQ ID NO: 12). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VL FR1 (SEQ ID NO: 61), and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VL FR1 (SEQ ID NO: 61), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), and VL FR2 (SEQ ID NO: 12). In other embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), and VL FR4 (SEQ ID NO: 16).In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR2 (SEQ ID NO: 12). In other embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR4 (SEQ ID NO: 58), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), and VL FR2 (SEQ ID NO: 12).In some embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR2 (SEQ ID NO: 12). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In some embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16).In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR2 (SEQ ID NO: 12). In one embodiment, the antibody comprises VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In other embodiments, the antibody comprises VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VL FR1 (SEQ ID NO: 61), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16).In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VL FR1 (SEQ ID NO: 61), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR3 (SEQ ID NO: 56), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64).In one embodiment, the antibody comprises VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), and VL FR1 (SEQ ID NO: 61). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), and VL FR2 (SEQ ID NO: 12). In other embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), and VL FR3 (SEQ ID NO: 64). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), and VL FR2 (SEQ ID NO: 12). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), and VL FR3 (SEQ ID NO: 64).In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR2 (SEQ ID NO: 12). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR3 (SEQ ID NO: 64). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64).In one embodiment, the antibody comprises VHFR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR2 (SEQ ID NO: 12). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16).In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR2 (SEQ ID NO: 12). In other embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In some embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In other embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16).In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VL FR1 (SEQ ID NO: 61), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16).In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16).In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16).In one embodiment, the antibody comprises VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR2 (SEQ ID NO: 12). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12) and VL FR3 (SEQ ID NO: 64). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12) and VL FR4 (SEQ ID NO: 16).In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In other embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO:52), VH FR2 (SEQ ID NO:54), VH FR4 (SEQ ID NO:58), VL FR1 (SEQ ID NO:61), VL FR2 (SEQ ID NO:12), and VL FR4 (SEQ ID NO:16).In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO:54), VH FR3 (SEQ ID NO:56), VH FR4 (SEQ ID NO:58), VL FR1 (SEQ ID NO:61), VL FR2 (SEQ ID NO:12), and VL FR3 (SEQ ID NO:64).In some embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO:54), VH FR3 (SEQ ID NO:56), VLFR1 (SEQ ID NO:61), VL FR2 (SEQ ID NO:12), VL FR3 (SEQ ID NO:64), and VL FR4 (SEQ ID NO:16).In another embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR3 (SEQ ID NO: 64). In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VHFR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16).In another embodiment, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR2 (SEQ ID NO: 54), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In other embodiments, the antibody comprises VH FR1 (SEQ ID NO: 52), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In one embodiment, the antibody comprises VH FR2 (SEQ ID NO: 54), VH FR3 (SEQ ID NO: 56), VH FR4 (SEQ ID NO: 58), VL FR1 (SEQ ID NO: 61), VL FR2 (SEQ ID NO: 12), VL FR3 (SEQ ID NO: 64), and VL FR4 (SEQ ID NO: 16). In some embodiments, the antibody comprises any combination of VH FR (SEQ ID NO: 52, 54, 56, 58) and VL FR (SEQ ID NO: 61, 12, 64, 16) listed in Tables 3-4.

[0279] In some embodiments, the antibodies provided herein comprise a VH region or a VH domain. In other embodiments, the antibodies provided herein comprise a VL region or a VL domain. In certain embodiments, the antibodies provided herein have (i) a VH domain or a VH region; and / or (ii) a combination of a VL domain or a VL region. In yet other embodiments, the antibodies provided herein have (i) a VH domain or a VH region; and / or (ii) a combination of a VL domain or a VL region selected from the group consisting of SEQ ID NO: 18, 46, 67, 133, 138, 141, 9, 22, 27, 32, 36, 42, 50, 60, 71, 76, 80, 85, 90, 123, and 127, as described in Tables 9-10. In yet other embodiments, the antibodies provided herein have a combination of: (i) a VH domain or VH region; and / or (ii) a VL domain or VL region of any one of antibodies SIRPAB-1, SIRPAB-2, SIRPAB-3, SIRPAB-4, SIRPAB-5, SIRPAB-6, SIRPAB-7, SIRPAB-8, SIRPAB-9, SIRPAB-10, SIRPAB-11, SIRPAB-12, SIRPAB-13, SIRPAB-17, SIRPAB-18, SIRPAB-19, SIRPAB-20, or SIRPAB-21, as listed in Tables 9-10.

[0280] In certain embodiments, the antibodies provided herein comprise a VH region comprising: (1) a VH CDR1 having an amino acid sequence selected from the group consisting of SEQ ID NOs: 78 and 82; (2) a VH CDR2 having an amino acid sequence selected from the group consisting of SEQ ID NOs: 69 and 83; and (3) a VH CDR3 having an amino acid sequence of SEQ ID NO: 57; and a VL region selected from the group consisting of SEQ ID NOs: 18, 46, 67, 133, 138, and 141, as listed in Table 9. In some embodiments, the VL region has the amino acid sequence of SEQ ID NO: 18. In other embodiments, the VL region has the amino acid sequence of SEQ ID NO: 46. In some embodiments, the VL region has the amino acid sequence of SEQ ID NO: 67.

[0281] In other embodiments, the antibodies provided herein comprise a VH region selected from the group consisting of SEQ ID NOs: 9, 22, 27, 32, 36, 42, 50, 60, 71, 76, 80, 85, 90, 123, and 127, as listed in Table 10; and a VL region comprising: (1) a VL CDR1 having the amino acid sequence of SEQ ID NO: 62; (2) a VL CDR2 having the amino acid sequence of SEQ ID NO: 63; and (3) a VL CDR3 having the amino acid sequence of SEQ ID NO: 65. In some embodiments, the VH region has the amino acid sequence of SEQ ID NO: 9. In some embodiments, the VH region has the amino acid sequence of SEQ ID NO: 22. In some embodiments, the VH region has the amino acid sequence of SEQ ID NO: 27. In some embodiments, the VH region has the amino acid sequence of SEQ ID NO: 32. In some embodiments, the VH region has the amino acid sequence of SEQ ID NO: 36. In some embodiments, the VH region has the amino acid sequence of SEQ ID NO: 42. In some embodiments, the VH region has the amino acid sequence of SEQ ID NO: 50. In some embodiments, the VH region has the amino acid sequence of SEQ ID NO: 60. In some embodiments, the VH region has the amino acid sequence of SEQ ID NO: 71. In some embodiments, the VH region has the amino acid sequence of SEQ ID NO: 76. In some embodiments, the VH region has the amino acid sequence of SEQ ID NO: 80. In some embodiments, the VH region has the amino acid sequence of SEQ ID NO: 85. In some embodiments, the VH region has the amino acid sequence of SEQ ID NO: 90. In some embodiments, the VH region has the amino acid sequence of SEQ ID NO: 123. In some embodiments, the VH region has the amino acid sequence of SEQ ID NO: 127.

[0282] Table 9. VL domain amino acid sequences

[0283]

[0284]

[0285] Table 10. VH domain amino acid sequences

[0286]

[0287]

[0288]

[0289] Also provided herein are isolated nucleic acid molecules encoding immunoglobulin heavy chains, light chains, VH regions, VL regions, VH CDR1, VH CDR2, VHCDR3, VL CDR1, VL CDR2 and / or VL CDR3 of anti-SIRPα antibodies that bind to a SIRPα polypeptide, a SIRPα polypeptide fragment, a SIRPα peptide or a SIRPα epitope. Exemplary nucleic acid sequences of the VL and VH regions of any of the antibodies SIRPAB-1, SIRPAB-2, SIRPAB-3, SIRPAB-4, SIRPAB-5, SIRPAB-6, SIRPAB-7, SIRPAB-8, SIRPAB-9, SIRPAB-10, SIRPAB-11, SIRPAB-12, SIRPAB-13, SIRPAB-18, SIRPAB-19, SIRPAB-20 or SIRPAB-21 are shown in Tables 11-12.

[0290] Table 11. VL nucleic acid sequences

[0291]

[0292]

[0293]

[0294]

[0295] Table 12. VH nucleic acid sequences

[0296]

[0297]

[0298]

[0299]

[0300]

[0301] In some embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB-1. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 9 and the VL amino acid sequence of SEQ ID NO: 18.

[0302] In other embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB-2. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 22 and the VL amino acid sequence of SEQ ID NO: 18.

[0303] In some embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB-3. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 27 and the VL amino acid sequence of SEQ ID NO: 18.

[0304] In other embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB-4. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 32 and the VL amino acid sequence of SEQ ID NO: 18.

[0305] In some embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB-5. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 36 and the VL amino acid sequence of SEQ ID NO: 18.

[0306] Additionally, in some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:42 and the VL amino acid sequence of SEQ ID NO:18. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:50 and the VL amino acid sequence of SEQ ID NO:18. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:60 and the VL amino acid sequence of SEQ ID NO:18. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:71 and the VL amino acid sequence of SEQ ID NO:18. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:76 and the VL amino acid sequence of SEQ ID NO:18. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:80 and the VL amino acid sequence of SEQ ID NO:18. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:85 and the VL amino acid sequence of SEQ ID NO:18. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:90 and the VL amino acid sequence of SEQ ID NO:18. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 123, and the VL amino acid sequence of SEQ ID NO: 18. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 127 and the VL amino acid sequence of SEQ ID NO: 18.

[0307] In other embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB-6. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 42 and the VL amino acid sequence of SEQ ID NO: 46.

[0308] In some embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB-7. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 50 and the VL amino acid sequence of SEQ ID NO: 46.

[0309] In addition, in some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 9 and the VL amino acid sequence of SEQ ID NO: 46. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 22 and the VL amino acid sequence of SEQ ID NO: 46. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 27 and the VL amino acid sequence of SEQ ID NO: 46. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 32 and the VL amino acid sequence of SEQ ID NO: 46. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 36 and the VL amino acid sequence of SEQ ID NO: 46. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 60 and the VL amino acid sequence of SEQ ID NO: 46. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 71 and the VL amino acid sequence of SEQ ID NO: 46. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 76 and the VL amino acid sequence of SEQ ID NO: 46. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 80 and the VL amino acid sequence of SEQ ID NO: 46. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 85 and the VL amino acid sequence of SEQ ID NO: 46. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 90 and the VL amino acid sequence of SEQ ID NO: 46. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 123 and the VL amino acid sequence of SEQ ID NO: 46. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 127 and the VL amino acid sequence of SEQ ID NO: 46.

[0310] In other embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB-8. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 60 and the VL amino acid sequence of SEQ ID NO: 67.

[0311] In some embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB-9. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 71 and the VL amino acid sequence of SEQ ID NO: 67.

[0312] In other embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB-10. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 76 and the VL amino acid sequence of SEQ ID NO: 67.

[0313] In some embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB- 11. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 80 and the VL amino acid sequence of SEQ ID NO: 67.

[0314] In other embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB- 12. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 85 and the VL amino acid sequence of SEQ ID NO: 67.

[0315] In some embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB- 13. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 90 and the VL amino acid sequence of SEQ ID NO: 67.

[0316] In addition, in some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 9 and the VL amino acid sequence of SEQ ID NO: 67. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 22 and the VL amino acid sequence of SEQ ID NO: 67. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 27 and the VL amino acid sequence of SEQ ID NO: 67. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 32 and the VL amino acid sequence of SEQ ID NO: 67. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 36 and the VL amino acid sequence of SEQ ID NO: 67. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 42 and the VL amino acid sequence of SEQ ID NO: 67. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 50 and the VL amino acid sequence of SEQ ID NO: 67. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 123 and the VL amino acid sequence of SEQ ID NO: 67. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 127 and the VL amino acid sequence of SEQ ID NO: 67.

[0317] In some embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB- 17. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 123 and the VL amino acid sequence of SEQ ID NO: 18.

[0318] In other embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB- 18. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 127 and the VL amino acid sequence of SEQ ID NO: 18.

[0319] In some embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB-19. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 127 and the VL amino acid sequence of SEQ ID NO: 133.

[0320] Additionally, in some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 9 and the VL amino acid sequence of SEQ ID NO: 133. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 22 and the VL amino acid sequence of SEQ ID NO: 133. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 27 and the VL amino acid sequence of SEQ ID NO: 133. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 32 and the VL amino acid sequence of SEQ ID NO: 133. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 36 and the VL amino acid sequence of SEQ ID NO: 133. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 42 and the VL amino acid sequence of SEQ ID NO: 133. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 50 and the VL amino acid sequence of SEQ ID NO: 133. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO: 60 and the VL amino acid sequence of SEQ ID NO: 133. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:71 and the VL amino acid sequence of SEQ ID NO:133. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:76 and the VL amino acid sequence of SEQ ID NO:133. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:80 and the VL amino acid sequence of SEQ ID NO:133. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:85 and the VL amino acid sequence of SEQ ID NO:133. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:90 and the VL amino acid sequence of SEQ ID NO:133. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:123 and the VL amino acid sequence of SEQ ID NO:133.

[0321] In other embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB-20. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 127 and the VL amino acid sequence of SEQ ID NO: 138.

[0322] Additionally, in some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:9 and the VL amino acid sequence of SEQ ID NO:138. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:22 and the VL amino acid sequence of SEQ ID NO:138. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:27 and the VL amino acid sequence of SEQ ID NO:138. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:32 and the VL amino acid sequence of SEQ ID NO:138. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:36 and the VL amino acid sequence of SEQ ID NO:138. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:42 and the VL amino acid sequence of SEQ ID NO:138. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:50 and the VL amino acid sequence of SEQ ID NO:138. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:60 and the VL amino acid sequence of SEQ ID NO:138. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:71 and the VL amino acid sequence of SEQ ID NO: 138. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:76 and the VL amino acid sequence of SEQ ID NO:138. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:80 and the VL amino acid sequence of SEQ ID NO:138. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:85 and the VL amino acid sequence of SEQ ID NO:138. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:90 and the VL amino acid sequence of SEQ ID NO:138. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:123 and the VL amino acid sequence of SEQ ID NO:138.

[0323] In some embodiments, the antibodies provided herein have the VH and VL amino acid sequences of SIRPAB-21. In some embodiments, the antibodies comprise the VH amino acid sequence of SEQ ID NO: 127 and the VL amino acid sequence of SEQ ID NO: 141.

[0324] Additionally, in some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:9 and the VL amino acid sequence of SEQ ID NO:141. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:22 and the VL amino acid sequence of SEQ ID NO:141. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:27 and the VL amino acid sequence of SEQ ID NO:141. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:32 and the VL amino acid sequence of SEQ ID NO:141. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:36 and the VL amino acid sequence of SEQ ID NO:141. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:42 and the VL amino acid sequence of SEQ ID NO:141. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:50 and the VL amino acid sequence of SEQ ID NO:141. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:60 and the VL amino acid sequence of SEQ ID NO:141. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:71 and the VL amino acid sequence of SEQ ID NO:141. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:76 and the VL amino acid sequence of SEQ ID NO:141. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:80 and the VL amino acid sequence of SEQ ID NO:141. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:85 and the VL amino acid sequence of SEQ ID NO:141. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:90 and the VL amino acid sequence of SEQ ID NO:141. In some embodiments, the antibody comprises the VH amino acid sequence of SEQ ID NO:123 and the VL amino acid sequence of SEQ ID NO:141.

[0325] In certain embodiments, an antibody or antigen-binding fragment thereof described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein the light chain comprises a constant region having the amino acid sequence:

[0326] RTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESV TEQDSKDSTYSLSSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC (SEQ ID NO: 211).

[0327] In other embodiments, an antibody or antigen-binding fragment thereof described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein the heavy chain comprises a human IgG1 Fc region having the amino acid sequence:

[0328] ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKS CDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKC K VSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK (SEQ ID NO: 155, K322 highlighted).

[0329] In some embodiments, an antibody or antigen-binding fragment thereof described herein that specifically binds to a SIRPα polypeptide, such as the ECD of SIRPα (eg, human SIRPα), comprises a light chain and a heavy chain, wherein the heavy chain does not comprise a human IgG1 Fc region having the amino acid sequence of SEQ ID NO: 155.

[0330] In certain embodiments, an antibody or antigen-binding fragment thereof described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein the heavy chain comprises a human IgG1-K322A Fc region having the amino acid sequence:

[0331] ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKS CDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKC A VSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK (SEQ ID NO: 157, K322A substitution highlighted).

[0332] In some embodiments, an antibody or antigen-binding fragment thereof described herein that specifically binds to a SIRPα polypeptide, e.g., an ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein the heavy chain comprises a human IgG4 Fc region having the amino acid sequence: ASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTKTYTCNVDHKPSNTKVDKRVESKYGPPCP S CPAPEF L GGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQP REPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK(SEQ ID NO:156, S228 and L235 highlighted).

[0333] In another embodiment, an antibody or antigen-binding fragment thereof described herein that specifically binds to a SIRPα polypeptide, e.g., an ECD of SIRPα, e.g., human SIRPα, comprises a light chain and a heavy chain, wherein the heavy chain comprises a human IgG4β Fc region having the amino acid sequence: ASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTKTYTCNVDHKPSNTKVDKRVESKYGPPCP P CPAPEFLGPSVFLFPPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKA KGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK(SEQ ID NO:158, S228P substitution highlighted).

[0334] In yet another embodiment, an antibody or antigen-binding fragment thereof described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα, e.g., human SIRPα, comprises a light chain and a heavy chain, wherein the heavy chain comprises a human IgG4 PE Fc region having the amino acid sequence: ASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTKTYTCNVDHKPSNTKVDKRVESKYGPPCP P CPAPEF E GGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQP REPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK(SEQ ID NO:159, S228P and L235E superseded highlighted).

[0335] In some embodiments, an antibody or antigen-binding fragment thereof described herein that specifically binds to a SIRPα polypeptide, such as the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein the heavy chain does not comprise a human IgG4 PE Fc region having the amino acid sequence of SEQ ID NO: 159.

[0336] In yet another embodiment, the antibody or antigen-binding fragment thereof described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα, e.g., human SIRPα, comprises a light chain and a heavy chain, wherein the light chain comprises a constant region having the amino acid sequence of SEQ ID NO: 211; and the heavy chain comprises an Fc region having an amino acid sequence selected from the group consisting of SEQ ID NOs: 144 and 155-159.

[0337] In certain embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, such as the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein the light chain comprises the following amino acid sequence:

[0338] DIQMTQSPSSVSASVGDRVTITCRASQGISSWLAWYQQKPGKAPKLLIYAASNLQSGVPSRFSGSGSGTDFTLTISSLQPEDFATYYCQQGASFPITFGGGTKVEIKRT VAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC(SEQ IDNO:143, LC_SIRPAB-11).

[0339] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, such as the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein the heavy chain comprises the following amino acid sequence:

[0340] QVQLVQSGAEVKKPGASVKVSCKASGYTFRGYGISWVRQAPGQGLEWMGWISAYGGETNYAQKLQGRVTMTTDTSSTAYMELRSLRSDDTAVYYCAREAGSSWYDFDLWGRGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWN SGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKC K VSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK (SEQ ID NO: 142, HC_SIRPAB-11, K322 highlighted).

[0341] In other embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, such as the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein the heavy chain comprises the following amino acid sequence:

[0342] QVQLVQSGAEVKKPGASVKVSCKASGYTFRGYGISWVRQAPGQGLEWMGWISAYGGETNYAQKLQGRVTMTTDTSSTAYMELRSLRSDDTAVYYCAREAGSSWYDFDLWGRGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWN SGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKC AVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK(SEQ ID NO:119, HC_SIRPAB-11-IgG1-K322A, K322A substitution highlighted).

[0343] In another embodiment, an antibody described herein that specifically binds to a SIRPα polypeptide, eg, the ECD of SIRPα (eg, human SIRPα), comprises a light chain and a heavy chain, wherein the heavy chain comprises the following amino acid sequence:

[0344] (SEQ ID NO: 112, HC_SIRPAB-11-IgG4P, IgG4P Fc backbone is italicized and underlined).

[0345] In yet another embodiment, an antibody described herein that specifically binds to a SIRPα polypeptide, eg, the ECD of SIRPα (eg, human SIRPα), comprises a light chain and a heavy chain, wherein the heavy chain comprises the following amino acid sequence:

[0346] (SEQ ID NO: 120, HC_SIRPAB-11-IgG4PE, IgG4PE Fc backbone is italicized and underlined).

[0347] In yet another embodiment, an antibody described herein that specifically binds to a SIRPα polypeptide, eg, the ECD of SIRPα (eg, human SIRPα), comprises a light chain and a heavy chain, wherein the heavy chain comprises the following amino acid sequence:

[0348] (SEQ ID NO:98, HC_SIRPAB-11-IgG1-AAS, IgG1-AAS Fc backbone is italicized and underlined).

[0349] In a specific embodiment, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 143; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 142.

[0350] In another specific embodiment, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 143; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 119.

[0351] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 143; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 98.

[0352] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 143; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 120.

[0353] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 143; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 112.

[0354] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 143; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 204.

[0355] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 143; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 205.

[0356] In yet another specific embodiment, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 200; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 212.

[0357] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 200; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 213.

[0358] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 200; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 214.

[0359] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 200; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 215.

[0360] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 200; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 216.

[0361] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 202; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 217.

[0362] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 202; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 218.

[0363] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 143; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 219.

[0364] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 143; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 220.

[0365] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 143; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 221.

[0366] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 143; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 222.

[0367] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 200; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 223.

[0368] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 200; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 207.

[0369] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 208; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 117.

[0370] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 209; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 110.

[0371] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 210; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 148.

[0372] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 143; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 106.

[0373] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 143; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 118.

[0374] In some embodiments, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 143; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 111.

[0375] Exemplary light and heavy chain sequences are summarized below in Table 13:

[0376] Table 13: Light and heavy chain sequences

[0377]

[0378]

[0379]

[0380]

[0381]

[0382]

[0383]

[0384]

[0385] In some embodiments, the antibodies provided herein comprise any combination or arrangement of any light chain provided herein and any heavy chain provided herein. In certain embodiments, the antibodies provided herein comprise light and heavy chain pairs as listed in Table 14 below:

[0386] Table 14: Exemplary light chain and heavy chain pairs of anti-SIRPα antibodies

[0387] Antibody light chain Heavy chain SIRPAB-1 SEQ ID NO:200 SEQ ID NO:212 SIRPAB-2 SEQ ID NO:200 SEQ ID NO:213 SIRPAB-3 SEQ ID NO:200 SEQ ID NO:214 SIRPAB-4 SEQ ID NO:200 SEQ ID NO:215 SIRPAB-5 SEQ ID NO:200 SEQ ID NO:216 SIRPAB-6 SEQ ID NO:202 SEQ ID NO:217 SIRPAB-7 SEQ ID NO:202 SEQ ID NO:218 SIRPAB-8 SEQ ID NO:143 SEQ ID NO:219 SIRPAB-9 SEQ ID NO:143 SEQ ID NO:220 SIRPAB-10 SEQ ID NO:143 SEQ ID NO:221 SIRPAB-11 SEQ ID NO:143 SEQ ID NO:142 SIRPAB-12 SEQ ID NO:143 SEQ ID NO:204 SIRPAB-13 SEQ ID NO:143 SEQ ID NO:222 SIRPAB-17 SEQ ID NO:200 SEQ ID NO:223 SIRPAB-18 SEQ ID NO:200 SEQ ID NO:207 SIRPAB-19 SEQ ID NO:208 SEQ ID NO:117 SIRPAB-20 SEQ ID NO:209 SEQ ID NO:110 SIRPAB-21 SEQ ID NO:210 SEQ ID NO:148 SIRPAB-11-K322A SEQ ID NO:143 SEQ ID NO:119 SIRPAB-11-AAS SEQ ID NO:143 SEQ ID NO:98 SIRPAB-11-4PE SEQ ID NO:143 SEQ ID NO:120 SIRPAB-11-4P SEQ ID NO:143 SEQ ID NO:112 SIRPAB-12-K322A SEQ ID NO:143 SEQ ID NO:205 SIRPAB-12-AAS SEQ ID NO:143 SEQ ID NO:106 SIRPAB-12-4PE SEQ ID NO:143 SEQ ID NO:118 SIRPAB-12-4P SEQ ID NO:143 SEQ ID NO:111

[0388] In yet another specific embodiment, an antibody described herein that specifically binds to a SIRPα polypeptide, e.g., the ECD of SIRPα (e.g., human SIRPα), comprises a light chain and a heavy chain, wherein (i) the light chain comprises the amino acid sequence of SEQ ID NO: 200; and (ii) the heavy chain comprises the amino acid sequence of SEQ ID NO: 213.

[0389] In yet another aspect, antibodies that compete with one of the exemplified antibodies or functional fragments for binding to SIRPα are provided. Such antibodies may also bind to the same epitope or overlapping epitope as one of the antibodies exemplified herein. It is expected that antibodies and fragments that compete with or bind to the same epitope as the exemplified antibodies exhibit similar functional properties. Exemplary antigen-binding proteins and fragments include those having VH and VL regions and CDRs provided herein, including those in Tables 1-4 and 9-10. Thus, as a specific example, the antibodies provided include antibodies that compete with antibodies comprising: (a) 1, 2, 3, 4, 5 or all 6 CDRs listed for the antibodies listed in Tables 1-2; (b) VH and VL selected from the VH and VL regions listed for the antibodies listed in Tables 9-10; or (c) two light chains and two heavy chains comprising VH and VL as specified for the antibodies listed in Tables 9-10. In some embodiments, the antibody is SIRPAB-1. In some embodiments, the antibody is SIRPAB-2. In some embodiments, the antibody is SIRPAB-3. In some embodiments, the antibody is SIRPAB-4. In some embodiments, the antibody is SIRPAB-5. In some embodiments, the antibody is SIRPAB-6. In some embodiments, the antibody is SIRPAB-7. In some embodiments, the antibody is SIRPAB-8. In some embodiments, the antibody is SIRPAB-9. In some embodiments, the antibody is SIRPAB-10. In some embodiments, the antibody is SIRPAB-11. In some embodiments, the antibody is SIRPAB-12. In some embodiments, the antibody is SIRPAB-13. In some embodiments, the antibody is SIRPAB-17. In some embodiments, the antibody is SIRPAB-18. In some embodiments, the antibody is SIRPAB-19. In some embodiments, the antibody is SIRPAB-20. In some embodiments, the antibody is SIRPAB-21.

[0390] In another aspect, the antibodies or antigen-binding fragments thereof provided herein bind to a region of human SIRPα or cynomolgus monkey SIRPα, including an epitope. For example, in some embodiments, the antibodies provided herein bind to a region of human SIRPα (SEQ ID NO: 146), comprising amino acid residues 30 to 98 of human SIRPα. In another aspect, the antibodies provided herein bind to a specific epitope of human SIRPα.

[0391] In certain embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 30-36 (SEQ ID NO: 147) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 30-52 (SEQ ID NO: 160) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 30-67 (SEQ ID NO: 161) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 30-69 (SEQ ID NO: 162) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 30-74 (SEQ ID NO: 163) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 30-93 (SEQ ID NO: 164) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 30-95 (SEQ ID NO: 165) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 30-96 (SEQ ID NO: 166) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 30-98 (SEQ ID NO: 167) within the amino acid sequence of SEQ ID NO: 146.

[0392] In certain embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 36-52 (SEQ ID NO: 168) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 36-67 (SEQ ID NO: 169) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 36-69 (SEQ ID NO: 170) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 36-74 (SEQ ID NO: 171) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 36-93 (SEQ ID NO: 172) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 36-95 (SEQ ID NO: 173) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 36-96 (SEQ ID NO: 174) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 36-98 (SEQ ID NO: 175) within the amino acid sequence of SEQ ID NO: 146.

[0393] In certain embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 52-67 (SEQ ID NO: 176) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 52-69 (SEQ ID NO: 177) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 52-74 (SEQ ID NO: 178) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 52-93 (SEQ ID NO: 179) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 52-95 (SEQ ID NO: 180) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 52-96 (SEQ ID NO: 181) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 52-98 (SEQ ID NO: 182) within the amino acid sequence of SEQ ID NO: 146.

[0394] In certain embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 67-69 (amino acid sequence having TKR) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 67-74 (SEQ ID NO: 183) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 67-93 (SEQ ID NO: 184) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 67-95 (SEQ ID NO: 185) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 67-96 (SEQ ID NO: 186) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 67-98 within the amino acid sequence of SEQ ID NO: 146 (SEQ ID NO: 187).

[0395] In certain embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 69-74 (SEQ ID NO: 188) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 69-93 (SEQ ID NO: 189) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 69-95 (SEQ ID NO: 190) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 69-96 (SEQ ID NO: 191) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 69-98 (SEQ ID NO: 192) within the amino acid sequence of SEQ ID NO: 146.

[0396] In certain embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 74-93 (SEQ ID NO: 193) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 74-95 (SEQ ID NO: 194) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 74-96 (SEQ ID NO: 195) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 74-98 (SEQ ID NO: 196) within the amino acid sequence of SEQ ID NO: 146.

[0397] In certain embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 93-95 (amino acid sequence having KFR) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 93-96 (SEQ ID NO: 198) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 93-98 (SEQ ID NO: 199) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 95-96 (amino acid sequence having RK) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 95-98 (SEQ ID NO: 201) within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one of residues 96-98 within the amino acid sequence of SEQ ID NO: 146 (having the amino acid sequence of KGS).

[0398] In certain embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one residue within the amino acid sequence of SEQ ID NO: 146 selected from the group consisting of L30, I36, Q52, T67, R69, F74, K93, R95, K96, and S98. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to at least one residue within the amino acid sequence of SEQ ID NO: 146 selected from the group consisting of T67, R69, R95, K96, and S98.

[0399] In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to two or more residues within the amino acid sequence of SEQ ID NO: 146, the residues being selected from the group consisting of L30, I36, Q52, T67, R69, F74, K93, R95, K96, and S98. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to two or more residues within the amino acid sequence of SEQ ID NO: 146, the residues being selected from the group consisting of T67, R69, R95, K96, and S98.

[0400] In other embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to three or more residues within the amino acid sequence of SEQ ID NO: 146, the residues being selected from the group consisting of L30, I36, Q52, T67, R69, F74, K93, R95, K96, and S98. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to three or more residues within the amino acid sequence of SEQ ID NO: 146, the residues being selected from the group consisting of T67, R69, R95, K96, and S98.

[0401] In certain embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to four or more residues within the amino acid sequence of SEQ ID NO: 146, the residues being selected from the group consisting of L30, I36, Q52, T67, R69, F74, K93, R95, K96, and S98. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to four or more residues within the amino acid sequence of SEQ ID NO: 146, the residues being selected from the group consisting of T67, R69, R95, K96, and S98.

[0402] In one embodiment, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to five or more residues within the amino acid sequence of SEQ ID NO: 146, the residues being selected from the group consisting of L30, I36, Q52, T67, R69, F74, K93, R95, K96, and S98. In other embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to five residues within the amino acid sequence of SEQ ID NO: 146, the residues consisting of T67, R69, R95, K96, and S98.

[0403] In another embodiment, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to six or more residues within the amino acid sequence of SEQ ID NO: 146, said residues being selected from the group consisting of: L30, I36, Q52, T67, R69, F74, K93, R95, K96, and S98.

[0404] In yet another embodiment, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to seven or more residues within the amino acid sequence of SEQ ID NO: 146, said residues being selected from the group consisting of: L30, I36, Q52, T67, R69, F74, K93, R95, K96, and S98.

[0405] In yet another embodiment, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to eight or more residues within the amino acid sequence of SEQ ID NO: 146, said residues being selected from the group consisting of: L30, I36, Q52, T67, R69, F74, K93, R95, K96, and S98.

[0406] In certain embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to nine or more residues within the amino acid sequence of SEQ ID NO: 146, selected from the group consisting of: L30, I36, Q52, T67, R69, F74, K93, R95, K96, and S98.

[0407] In other embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to all ten residues within the amino acid sequence of SEQ ID NO: 146, selected from the group consisting of: L30, I36, Q52, T67, R69, F74, K93, R95, K96, and S98.

[0408] In another embodiment, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to L30 within the amino acid sequence of SEQ ID NO: 146. In another embodiment, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to I36 within the amino acid sequence of SEQ ID NO: 146. In a specific embodiment, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to Q52 within the amino acid sequence of SEQ ID NO: 146. In a specific embodiment, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to T67 within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to R69 within the amino acid sequence of SEQ ID NO: 146. In other embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to F74 within the amino acid sequence of SEQ ID NO: 146. In another embodiment, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to K93 within the amino acid sequence of SEQ ID NO: 146. In yet another embodiment, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to R95 within the amino acid sequence of SEQ ID NO: 146. In yet another embodiment, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to K96 within the amino acid sequence of SEQ ID NO: 146. In some embodiments, the antibody or antigen-binding fragment thereof, when bound to SIRPα, binds to S98 within the amino acid sequence of SEQ ID NO: 146. Any combination of two, three, four, five, six, seven, eight, nine, or ten of the above-mentioned amino acid SIRPα binding sites is also contemplated.

[0409] On the one hand, provided herein are antibodies that specifically bind to SIRPα and can reduce the binding between SIRPα and CD47. As known to those skilled in the art, there are a variety of naturally occurring SIRPα polymorphisms. The anti-SIRPα antibodies or fragments thereof provided herein can be bound to one, two, three, four, five, six, seven, eight, nine, ten or more or all of the SIRPα polymorphisms known to those skilled in the art, such as Takenaka K et al., Nat Immunol. 2007 December; 8(12): one, two, three, four, five, six, seven, eight, nine, ten or more or all of the SIRPα polymorphisms described in 1313-23. In some specific embodiments, the anti-SIRPα antibodies or fragments thereof provided herein can bind to one or more SIRPα polymorphisms selected from the group consisting of: SIRPαv1 whose IgV domain comprises SEQ ID NO: 149, SIRPαv2 whose IgV domain comprises SEQ ID NO: 150, SIRPαv3 whose IgV domain comprises SEQ ID NO: 151, SIRPαv4 whose IgV domain comprises SEQ ID NO: 152, SIRPαv5 whose IgV domain comprises SEQ ID NO: 153, and SIRPαv6 whose IgV domain comprises SEQ ID NO: 154, and / or reduce the binding between CD47 and one or more SIRPα polymorphisms selected from the group consisting of: SIRPαv1 whose IgV domain comprises SEQ ID NO: 149, SIRPαv2 whose IgV domain comprises SEQ ID NO: 150, SIRPαv3 whose IgV domain comprises SEQ ID NO: 151, SIRPαv4 whose IgV domain comprises SEQ ID NO: 152, SIRPαv5 whose IgV domain comprises SEQ ID NO: 153, and SIRPαv6 whose IgV domain comprises SEQ ID NO: 154. SIRPαv4 of NO: 152, SIRPαv5 of IgV domain comprising SEQ ID NO: 153, and SIRPαv6 of IgV domain comprising SEQ ID NO: 154.

[0410] In some embodiments, the anti-SIRPα antibodies or fragments thereof provided herein can bind to two or more SIRPα polymorphisms selected from the group consisting of: SIRPαv1 whose IgV domain comprises SEQ ID NO: 149, SIRPαv2 whose IgV domain comprises SEQ ID NO: 150, SIRPαv3 whose IgV domain comprises SEQ ID NO: 151, SIRPαv4 whose IgV domain comprises SEQ ID NO: 152, SIRPαv5 whose IgV domain comprises SEQ ID NO: 153, and SIRPαv6 whose IgV domain comprises SEQ ID NO: 154, and / or reduce the binding between CD47 and two or more SIRPα polymorphisms selected from the group consisting of: SIRPαv1 whose IgV domain comprises SEQ ID NO: 149, SIRPαv2 whose IgV domain comprises SEQ ID NO: 150, SIRPαv3 whose IgV domain comprises SEQ ID NO: 151, SIRPαv4 whose IgV domain comprises SEQ ID NO: 152, SIRPαv5 whose IgV domain comprises SEQ ID NO: 153, and SIRPαv6 whose IgV domain comprises SEQ ID NO: 154. SIRPαv4 of NO: 152, SIRPαv5 of IgV domain comprising SEQ ID NO: 153, and SIRPαv6 of IgV domain compri...

Claims

1. An antibody or antigen-binding fragment thereof that binds to human SIRPα, wherein the antibody or antigen-binding fragment thereof comprises: (a) a light chain variable region (VL), comprising The amino acid sequence of VL complementarity determining region 1 (CDR1) is shown in SEQ ID NO:62, The amino acid sequence of VL CDR2 is shown in SEQ ID NO:63, and VL CDR3 having an amino acid sequence as shown in SEQ ID NO:65; and (b) a heavy chain variable region (VH), comprising The amino acid sequence of VH CDR1 is shown in SEQ ID NO: 78, The amino acid sequence of VH CDR2 is shown in SEQ ID NO:69, and The amino acid sequence of VH CDR3 is shown in SEQ ID NO:

57.

2. The antibody or antigen-binding fragment thereof of claim 1, wherein the antibody or antigen-binding fragment thereof comprises a VL comprising the amino acid sequence shown in SEQ ID NO:

67.

3. The antibody or antigen-binding fragment thereof according to claim 1, wherein the antibody or antigen-binding fragment thereof comprises a VH comprising the amino acid sequence shown in SEQ ID NO:

80.

4. The antibody or antigen-binding fragment thereof according to claim 1, wherein the antibody or antigen-binding fragment thereof comprises: (a) a VL comprising the amino acid sequence shown in SEQ ID NO: 67; and (b) VH comprising the amino acid sequence shown in SEQ ID NO:

80. 5 . The antibody or antigen-binding fragment thereof according to claim 1 , wherein the antibody or antigen-binding fragment thereof comprises a human IgG1 Fc region or a mutant thereof.

6. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof comprises a human IgG1-K322A Fc region.

7. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof comprises a human IgG1-AAS Fc region.

8. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof comprises a human IgG4 Fc region or a mutant thereof.

9. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof comprises a human IgG4P Fc region.

10. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof comprises a human IgG4PE Fc region.

11. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain Fc region comprising an amino acid sequence selected from the group consisting of the amino acid sequences shown in SEQ ID NOs: 144 and 155-159.

12. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof further comprises a light chain constant region comprising the amino acid sequence shown in SEQ ID NO:

211.

13. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof comprises: (a) a light chain constant region comprising the amino acid sequence shown in SEQ ID NO: 211; and (b) a heavy chain Fc region comprising an amino acid sequence selected from the group consisting of amino acids shown in SEQ ID NOs: 144 and 155-159.

14. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof comprises a light chain comprising the amino acid sequence shown in SEQ ID NO:

143.

15. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence shown in SEQ ID NO:

142.

16. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain comprising the amino acid sequence shown in SEQ ID NO:

119.

17. The antibody or antigen-binding fragment of any one of claims 1-4, wherein the antibody or antigen-binding fragment comprises a heavy chain comprising the amino acid sequence shown in SEQ ID NO:

98.

18. The antibody or antigen-binding fragment of any one of claims 1-4, wherein the antibody or antigen-binding fragment comprises a heavy chain comprising the amino acid sequence shown in SEQ ID NO:

120.

19. The antibody or antigen-binding fragment of any one of claims 1-4, wherein the antibody or antigen-binding fragment comprises a heavy chain comprising the amino acid sequence shown in SEQ ID NO:

112.

20. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence shown in SEQ ID NO: 143; and (b) a heavy chain comprising the amino acid sequence shown in SEQ ID NO:

142.

21. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence shown in SEQ ID NO: 143; and (b) a heavy chain comprising the amino acid sequence shown in SEQ ID NO:

119.

22. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence shown in SEQ ID NO: 143; and (b) A heavy chain comprising the amino acid sequence shown in SEQ ID NO:

98.

23. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence shown in SEQ ID NO: 143; and (b) a heavy chain comprising the amino acid sequence shown in SEQ ID NO:

120.

24. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof comprises: (a) a light chain comprising the amino acid sequence shown in SEQ ID NO: 143; and (b) a heavy chain comprising the amino acid sequence shown in SEQ ID NO:

112.

25. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 4, wherein the antibody or antigen-binding fragment, when binding to SIRPα, binds to at least one of residues 67-98 within the amino acid sequence shown in SEQ ID NO:

146.

26. The antibody or antigen-binding fragment thereof according to claim 25, wherein the antibody or antigen-binding fragment, when binding to SIRPα, binds to at least one of residues 67-74 within the amino acid sequence shown in SEQ ID NO:

146.

27. The antibody or antigen-binding fragment thereof according to claim 25, wherein the antibody or antigen-binding fragment, when binding to SIRPα, binds to at least one of residues 93-98 within the amino acid sequence shown in SEQ ID NO:

146.

28. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 4, wherein the antibody or antigen-binding fragment, when binding to SIRPα, binds to at least one of residues 30-93 within the amino acid sequence shown in SEQ ID NO:

146.

29. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody or antigen-binding fragment, when bound to SIRPα, binds to at least one residue within the amino acid sequence shown in SEQ ID NO: 146 selected from the group consisting of: L30, I36, Q52, T67, R69, F74, K93, R95, K96 and S98.

30. The antibody or antigen-binding fragment thereof according to claim 29, wherein the antibody or antigen-binding fragment binds to L30 within the amino acid sequence shown in SEQ ID NO: 146 when binding to SIRPα.

31. The antibody or antigen-binding fragment thereof according to claim 29, wherein the antibody or antigen-binding fragment binds to I36 within the amino acid sequence shown in SEQ ID NO: 146 when binding to SIRPα.

32. The antibody or antigen-binding fragment thereof of claim 29, wherein the antibody or antigen-binding fragment binds to Q52 within the amino acid sequence shown in SEQ ID NO: 146 when binding to SIRPα.

33. The antibody or antigen-binding fragment thereof according to claim 29, wherein the antibody or antigen-binding fragment binds to T67 within the amino acid sequence shown in SEQ ID NO: 146 when binding to SIRPα.

34. The antibody or antigen-binding fragment thereof according to claim 29, wherein the antibody or antigen-binding fragment binds to R69 within the amino acid sequence shown in SEQ ID NO: 146 when binding to SIRPα.

35. The antibody or antigen-binding fragment thereof of claim 29, wherein the antibody or antigen-binding fragment binds to F74 within the amino acid sequence shown in SEQ ID NO: 146 when binding to SIRPα.

36. The antibody or antigen-binding fragment thereof of claim 29, wherein the antibody or antigen-binding fragment binds to K93 within the amino acid sequence shown in SEQ ID NO: 146 when binding to SIRPα.

37. The antibody or antigen-binding fragment thereof of claim 29, wherein the antibody or antigen-binding fragment binds to R95 within the amino acid sequence shown in SEQ ID NO: 146 when binding to SIRPα.

38. The antibody or antigen-binding fragment thereof of claim 29, wherein the antibody or antigen-binding fragment binds to K96 within the amino acid sequence shown in SEQ ID NO: 146 when binding to SIRPα.

39. The antibody or antigen-binding fragment thereof according to claim 29, wherein the antibody or antigen-binding fragment, when binding to SIRPα, binds to S98 within the amino acid sequence shown in SEQ ID NO:

146.

40. The antibody or antigen-binding fragment thereof according to claim 29, wherein the antibody or antigen-binding fragment, when binding to SIRPα, binds to T67, R69, R95, K96 and S98 within the amino acid sequence shown in SEQ ID NO:

146.

41. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof reduces the binding between SIRPα and CD47.

42. The antibody or antigen-binding fragment thereof according to claim 41, wherein the IgV domain of SIRPα comprises a haplotype selected from the group consisting of: an amino acid sequence as shown in SEQ ID NOS: 149, 150, 151, 152, 153 and 154.

43. The antibody or antigen-binding fragment thereof of claim 41, wherein the antibody or antigen-binding fragment thereof reduces binding of CD47 to each of the six SIRPα haplotypes, The six SIRPα haplotypes are composed of SIRPαv1, SIRPαv2, SIRPαv3, SIRPαv4, SIRPαv5 and SIRPαv6, and Wherein the IgV domain of SIRPαv1 comprises SEQ ID NO:149, the IgV domain of SIRPαv2 comprises SEQ ID NO:150, the IgV domain of SIRPαv3 comprises SEQ ID NO:151, the IgV domain of SIRPαv4 comprises SEQ ID NO:152, the IgV domain of SIRPαv5 comprises SEQ ID NO:153, and the IgV domain of SIRPαv6 comprises SEQ ID NO:

154.

44. The antibody or antigen-binding fragment thereof of claim 41, wherein CD47-SIRPα binding is reduced by 50%, 60%, 70%, 80%, 90%, 95% or 99%.

45. The antibody or antigen-binding fragment thereof of claim 41, wherein the EC of the antibody or antigen-binding fragment thereof for reducing CD47-SIRPα binding is 50 1 pM to 10 pM, 10 pM to 100 pM, 100 pM to 1 nM, 1 nM to 10 nM or 10 nM to 100 nM.

46. ​​The antibody or antigen-binding fragment thereof of claim 41, wherein the EC of the antibody or antigen-binding fragment thereof for reducing CD47-SIRPα binding is 50 It is 2nM, 2.1nM, 2.2nM, 2.3nM, 2.4nM, 2.5nM, 2.6nM, 2.7nM, 2.8nM, 2.9nM, 3nM, 3.1nM, 3.2nM, 3.3nM, 3.4nM, 3.5nM, 3.6nM, 3.7nM, 3.8nM, 3.9nM, 4.0nM, 4.1nM, 4.2nM, 4.3nM, 4.4nM, 4.5nM, 4.6nM, 4.7nM, 4.8nM, 4.9nM, 5.0nM, 5.1nM, 5.2nM, 5.3nM, 5.4nM, 5.5nM, 5.6nM, 5.7nM, 5.8nM, 5.9nM or 6.0nM.

47. The antibody or antigen-binding fragment thereof according to any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof specifically binds to one or more of the six SIRPα haplotypes, The six SIRPα haplotypes are composed of SIRPαv1, SIRPαv2, SIRPαv3, SIRPαv4, SIRPαv5 and SIRPαv6, and Wherein the IgV domain of SIRPαv1 comprises SEQ ID NO:149, the IgV domain of SIRPαv2 comprises SEQ ID NO:150, the IgV domain of SIRPαv3 comprises SEQ ID NO:151, the IgV domain of SIRPαv4 comprises SEQ ID NO:152, the IgV domain of SIRPαv5 comprises SEQ ID NO:153, and the IgV domain of SIRPαv6 comprises SEQ ID NO:

154.

48. The antibody or antigen-binding fragment thereof of claim 47, wherein the antibody or antigen-binding fragment thereof binds to each of the six SIRPα haplotypes.

49. The antibody or antigen-binding fragment thereof of claim 48, wherein the antibody or antigen-binding fragment thereof has a dissociation constant (K) of no more than 5 nM. D ) binds to each of the 6 SIRPα haplotypes.

50. The antibody or antigen-binding fragment thereof of claim 47, wherein the antibody or antigen-binding fragment thereof has a K of no greater than 0.2 nM. D Binds to purified SIRPαv1.

51. The antibody or antigen binding fragment thereof of claim 47, wherein the antibody or antigen binding fragment thereof has a K of 0.13 nM. D Binds to purified SIRPαv1.

52. The antibody or antigen binding fragment thereof of claim 47, wherein the antibody or antigen binding fragment thereof has a K of no greater than 5 nM. D Binds to purified SIRPαv2.

53. The antibody or Fab of claim 47, wherein the antibody or Fab of claim 47 has a K of 4.4 nM. D Binds to purified SIRPαv2.

54. The antibody or antigen-binding fragment thereof of claim 47, wherein the antibody or antigen-binding fragment thereof has a K of no greater than 0.2 nM. D Binds to purified SIRPαv3.

55. The antibody or antigen binding fragment thereof of claim 47, wherein the antibody or antigen binding fragment thereof has a K of 0.15 nM. D Binds to purified SIRPαv3.

56. The antibody or antigen-binding fragment thereof of claim 47, wherein the antibody or antigen-binding fragment thereof has a K of no greater than 2 nM. D Binds to purified SIRPαv4.

57. The antibody or antigen binding fragment thereof of claim 47, wherein the antibody or antigen binding fragment thereof has a K of 1.5 nM. D Binds to purified SIRPαv4.

58. The antibody or antigen-binding fragment thereof of claim 47, wherein the antibody or antigen-binding fragment thereof has a K of no greater than 0.7 nM. D Binds to purified SIRPαv5.

59. The antibody or antigen binding fragment thereof of claim 47, wherein the antibody or antigen binding fragment thereof has a K of 0.6 nM. D Binds to purified SIRPαv5.

60. The antibody or antigen-binding fragment thereof of claim 47, wherein the antibody or antigen-binding fragment thereof has a K of no greater than 0.2 nM. D Binds to purified SIRPαv6.

61. The antibody or antigen binding fragment thereof of claim 47, wherein the antibody or antigen binding fragment thereof has a K of 0.18 nM. D Binds to purified SIRPαv6.

62. The antibody or antigen-binding fragment thereof of claim 47, wherein the antibody or antigen-binding fragment thereof has an EC of 1 pM to 10 pM, 10 pM to 100 pM, 100 pM to 1 nM, 1 nM to 10 nM, or 10 nM to 100 nM. 50 Binds to human SIRPα expressed on cells.

63. The antibody or antigen-binding fragment thereof of claim 62, wherein the EC 50 It is 2nM, 2.1nM, 2.2nM, 2.3nM, 2.4nM, 2.5nM, 2.6nM, 2.7nM, 2.8nM, 2.9nM, 3nM, 3.1nM, 3.2nM, 3.3nM, 3.4nM, 3.5nM, 3.6nM, 3.7nM, 3.8nM, 3.9nM, 4.0nM, 4.1nM, 4.2nM, 4.3nM, 4.4nM, 4.5nM, 4.6nM, 4.7nM, 4.8nM, 4.9nM, 5.0nM, 5.1nM, 5.2nM, 5.3nM, 5.4nM, 5.5nM, 5.6nM, 5.7nM, 5.8nM, 5.9nM or 6.0nM.

64. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof specifically binds to human SIRPα and / or monkey SIRPα, but not to rodent SIRPα.

65. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof has an EC of 1 pM to 10 pM, 10 pM to 100 pM, 100 pM to 1 nM, 1 nM to 10 nM, or 10 nM to 100 nM. 50 Binds to cynomolgus monkey SIRPα expressed on cells.

66. The antibody or antigen-binding fragment thereof of claim 65, wherein the EC 50 It is 2nM, 2.1nM, 2.2nM, 2.3nM, 2.4nM, 2.5nM, 2.6nM, 2.7nM, 2.8nM, 2.9nM, 3nM, 3.1nM, 3.2nM, 3.3nM, 3.4nM, 3.5nM, 3.6nM, 3.7nM, 3.8nM, 3.9nM, 4.0nM, 4.1nM, 4.2nM, 4.3nM, 4.4nM, 4.5nM, 4.6nM, 4.7nM, 4.8nM, 4.9nM, 5.0nM, 5.1nM, 5.2nM, 5.3nM, 5.4nM, 5.5nM, 5.6nM, 5.7nM, 5.8nM, 5.9nM or 6.0nM.

67. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof enhances phagocytosis of cancer cells by co-cultured macrophages.

68. The antibody or antigen-binding fragment thereof of claim 67, wherein the antibody or antigen-binding fragment thereof, when used as a monotherapeutic agent, enhances phagocytosis of cancer cells by co-cultured macrophages.

69. The antibody or antigen-binding fragment thereof of claim 67, wherein the antibody or antigen-binding fragment thereof enhances phagocytosis of cancer cells by co-cultured macrophages when used in combination with a second therapeutic agent.

70. The antibody or antigen-binding fragment thereof of claim 69, wherein the second therapeutic agent is selected from the group consisting of cetuximab and rituximab.

71. The antibody or antigen-binding fragment thereof of claim 67, wherein SIRPα is expressed on macrophages, cancer cells, or both macrophages and cancer cells.

72. The antibody or antigen-binding fragment thereof of claim 71, wherein SIRPα is one or more of the six SIRPα haplotypes, The six SIRPα haplotypes are composed of SIRPαv1, SIRPαv2, SIRPαv3, SIRPαv4, SIRPαv5 and SIRPαv6, and Wherein the IgV domain of SIRPαv1 comprises SEQ ID NO:149, the IgV domain of SIRPαv2 comprises SEQ ID NO:150, the IgV domain of SIRPαv3 comprises SEQ ID NO:151, the IgV domain of SIRPαv4 comprises SEQ ID NO:152, the IgV domain of SIRPαv5 comprises SEQ ID NO:153, and the IgV domain of SIRPαv6 comprises SEQ ID NO:

154.

73. The antibody or antigen-binding fragment thereof of claim 67, wherein the antibody or antigen-binding fragment thereof increases the minimum percentage of phagocytic macrophages in a macrophage population to 10%, 20%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 99%.

74. The antibody or antigen binding fragment thereof of claim 67, wherein the antibody or antigen binding fragment thereof enhances phagocytosis of macrophages by 10%, 20%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 125%, 150%, 175%, 200%, 250%, 300%, 400%, 500%, 600%, 700%, 800%, 900% or 1000%.

75. The antibody or antigen-binding fragment thereof of claim 67, wherein the cancer cell is selected from the group consisting of colorectal cancer, head and neck squamous cell carcinoma, acute myeloid leukemia, and diffuse large B-cell lymphoma.

76. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof produces a synergistic effect when used in combination with a second therapeutic agent to enhance phagocytosis of cancer cells by co-cultured macrophages.

77. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof produces a synergistic effect when used in combination with a second therapeutic agent, rituximab, to enhance phagocytosis of cancer cells by co-cultured macrophages.

78. The antibody or antigen-binding fragment thereof of claim 76, wherein SIRPα is expressed on macrophages, cancer cells, or both macrophages and cancer cells.

79. The antibody or antigen-binding fragment thereof of claim 77, wherein SIRPα is expressed on macrophages, cancer cells, or both macrophages and cancer cells.

80. The antibody or antigen-binding fragment thereof of claim 78 or 79, wherein SIRPα is one or more of the six SIRPα haplotypes, The six SIRPα haplotypes are composed of SIRPαv1, SIRPαv2, SIRPαv3, SIRPαv4, SIRPαv5 and SIRPαv6, and Wherein the IgV domain of SIRPαv1 comprises SEQ ID NO:149, the IgV domain of SIRPαv2 comprises SEQ ID NO:150, the IgV domain of SIRPαv3 comprises SEQ ID NO:151, the IgV domain of SIRPαv4 comprises SEQ ID NO:152, the IgV domain of SIRPαv5 comprises SEQ ID NO:153, and the IgV domain of SIRPαv6 comprises SEQ ID NO:

154.

81. The antibody or antigen-binding fragment thereof of claim 76, wherein the difference between the percentage of phagocytic macrophages induced by the antibody or antigen-binding fragment together with the second therapeutic agent and the sum of the percentages of phagocytosis induced by the antibody or antigen-binding fragment and the second therapeutic agent separately is 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65% or 70%.

82. The antibody or antigen-binding fragment thereof of claim 77, wherein the difference between the percentage of phagocytic macrophages induced by the antibody or antigen-binding fragment together with the second therapeutic agent and the sum of the percentages of phagocytosis induced by the antibody or antigen-binding fragment and the second therapeutic agent separately is 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65% or 70%.

83. The antibody or antigen-binding fragment thereof of claim 76, wherein the percentage of phagocytic macrophages induced by the antibody or antigen-binding fragment together with the second therapeutic agent is increased by 10%, 20%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 125%, 150%, 175%, 200%, 250%, 300% or 400% relative to the sum of the percentages of phagocytosis induced by the antibody or antigen-binding fragment and the second therapeutic agent, respectively.

84. The antibody or antigen-binding fragment thereof of claim 77, wherein the percentage of phagocytic macrophages induced by the antibody or antigen-binding fragment together with the second therapeutic agent is increased by 10%, 20%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 125%, 150%, 175%, 200%, 250%, 300% or 400% relative to the sum of the percentages of phagocytosis induced by the antibody or antigen-binding fragment and the second therapeutic agent, respectively.

85. The antibody or antigen-binding fragment thereof of claim 76, wherein the cancer cell is selected from the group consisting of colorectal cancer, head and neck squamous cell carcinoma, acute myeloid leukemia, and diffuse large B-cell lymphoma.

86. The antibody or antigen-binding fragment thereof of claim 77, wherein the cancer cell is selected from the group consisting of colorectal cancer, head and neck squamous cell carcinoma, acute myeloid leukemia, and diffuse large B-cell lymphoma.

87. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof has attenuated ADCC activity, attenuated ADCP activity and / or attenuated CDC activity compared to an isotype control antibody.

88. The antibody or antigen-binding fragment thereof of claim 87, wherein the maximum ADCC activity is no greater than 5%, 10%, 20%, 30% or 40% of the cytotoxicity as measured by the percentage of target cells killed.

89. The antibody or antigen-binding fragment thereof of claim 87, wherein the maximum ADCP activity is no greater than 5%, 10%, 20% or 30% of phagocytic macrophages targeting autologous T cells and / or monocytes.

90. The antibody or antigen-binding fragment thereof of claim 87, wherein the antibody or antigen-binding fragment thereof has an EC50 of at least 100 μM in a CDC assay.

91. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof induces cytokine release no more than the level of cytokine release induced by an isotype control antibody.

92. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody is a monoclonal antibody.

93. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody is a humanized, human or chimeric antibody.

94. The antibody or antigen-binding fragment thereof of claim 93, wherein the humanized antibody is a deimmunized antibody or a composite human antibody.

95. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof is Fab, Fab', F(ab') 2 , Fv, scFv, dsFv, diabody, triabody, tetrabody, or a multispecific antibody formed by antibody fragments.

96. The antibody or antigen-binding fragment thereof of any one of claims 1 to 4, wherein the antibody or antigen-binding fragment thereof is conjugated to an agent.

97. The antibody or antigen-binding fragment thereof of claim 96, wherein the agent is selected from the group consisting of a radioisotope, a metal chelator, an enzyme, a fluorescent compound, a bioluminescent compound, and a chemiluminescent compound.

98. A composition comprising the antibody or antigen-binding fragment thereof as described in any one of claims 1 to 4 and a pharmaceutically acceptable carrier.

99. A composition comprising one or more polynucleotide molecules encoding both the VH and VL of an antibody as described in any one of claims 1 to 4, or encoding both the heavy chain and the light chain of an antibody as described in any one of claims 1 to 4.

100. The composition of claim 99, wherein the one or more polynucleotide molecules are operably linked to a promoter.

101. The composition of claim 99, wherein the one or more polynucleotide molecules are in a vector.

102. The composition of claim 99, wherein the one or more polynucleotide molecules are in a cell.

103. A cell comprising the vector of claim 101.

104. An isolated cell that produces the antibody or antigen-binding fragment thereof of any one of claims 1 to 4.

105. A kit comprising the antibody or antigen-binding fragment thereof according to any one of claims 1 to 4.

106. A use for preparing an antibody or an antigen-binding fragment thereof, wherein the antibody or the antigen-binding fragment thereof specifically binds to an epitope of human SIRPα, the use comprising culturing the cell according to claim 102 to express the antibody or the antigen-binding fragment thereof.

107. A use for preparing an antibody or an antigen-binding fragment thereof, wherein the antibody or the antigen-binding fragment thereof specifically binds to an epitope of human SIRPα, the use comprising expressing the polynucleotide molecule according to claim 99.

108. Use of the antibody or antigen-binding fragment of any one of claims 1-4 in the preparation of a medicament for treating cancer in a subject, wherein the cancer is a cancer selected from colorectal cancer, head and neck cancer, diffuse large B-cell lymphoma, and acute myeloid leukemia.

109. The use of claim 108, wherein the cancer cells, macrophages, or both cancer cells and macrophages express SIRPα.

110. The use of claim 109, wherein SIRPα is one or more of the six SIRPα haplotypes, The six SIRPα haplotypes consist of SIRPαv1, SIRPαv2, SIRPαv3, SIRPαv4, SIRPαv5, and SIRPαv6, and wherein SIRPa v1 comprises SEQ ID NO: 149 in the IgV domain, SIRPa v2 comprises SEQ ID NO: 150 in the IgV domain, SIRPa v3 comprises SEQ ID NO: 151 in the IgV domain, SIRPa v4 comprises SEQ ID NO: 152 in the IgV domain, SIRPα v5 comprises SEQ ID NO: 153 in the IgV domain, and SIRPα v6 comprises SEQ ID NO: 154 in the IgV domain.

111. The use according to claim 108, wherein the medicament is used in combination with a second therapeutic agent.

112. The use according to claim 111, wherein the second therapeutic agent is selected from the group consisting of cetuximab and rituximab.

113. The use of claim 108, wherein the subject is selected from the group consisting of humans, monkeys, mice, dogs, and rats.

Images