Anti-CD33 antibodies and methods of use thereof

Abstract

To provide therapeutic anti-CD33 antibodies and pharmaceutical compositions for treating diseases, disorders, and conditions associated with undesirable CD33 activity.SOLUTION: Provided is an antibody that binds to a CD33 protein, the antibody comprising a heavy chain variable region and a light chain variable region, the antibody comprising a combination of sequences in which HVR-H1 to HVR-H3 and HVR-L1 to HVR-L3 each comprise specific amino acid sequences.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 62 / 541,024, filed August 3, 2017, and U.S. Provisional Patent Application No. 62 / 667,388, filed May 4, 2018, which are incorporated herein by reference in their entireties.

[0002] Submission of sequence listing as an ASCII text file The contents of the following submission in an ASCII text file are incorporated herein by reference in their entirety: Sequence Listing Computer Readable Form (CRF) (File Name: 735022001740SEQLIST.TXT, Date Recorded: August 2, 2018, Size: 185 KB).

[0003] FIELD OF THE INVENTION The present disclosure relates to anti-CD33 antibodies and therapeutic uses of such antibodies. [Background technology]

[0004] The myeloid cell surface antigen CD33 precursor (CD33), also known as Siglec-3, is a type 1 immunoglobulin-like transmembrane protein expressed on immune and hematopoietic cells, including immature and mature myeloid cells, dendritic cells, and microglial cells (Crocker et al. (2007) Nat Rev Immunol. 7:255-266; McMillan and Crocker (2008) Carbohydr Res. 343:2050-2056; Von Gunten and Bochner (2008) Ann NY Acad Sci. 1143:61-82; Handgretinger et al. (1993) Immunol Lett. 37:223-228; and Hernandez-Caselles et al. (2006) J Leukoc Biol. 79:46-58). CD33 contains an Ig-like C2-type (immunoglobulin-like) and an Ig-like V-type (immunoglobulin-like) extracellular domain, as well as two ITIM-like motifs in its cytoplasmic domain. Three alternatively spliced ​​forms (isoforms) of CD33 have been identified, including a high-molecular-weight variant designated CD33M and a smaller isoform, CD33m, which lacks the Ig-like V-type domain (ligand-binding site) and the disulfide bond linking the V and C domains.

[0005] Genome-wide association studies (GWAS) conducted on expanded cohorts (e.g., several thousand individuals) have shown that the CD33 single nucleotide polymorphism (SNP) rs3865444 CC (also known as rs3826656) and rs3865444 AA has been identified as a genetic regulator of risk for late-onset Alzheimer's disease (AD). In oncology, CD33 variants resulting in reduced CD33 expression have been shown to be associated with improved survival from childhood acute myeloid leukemia (AML). 3-year overall survival from remission was significantly increased with the variant rs35112940. GG The rate was 84% ​​+ / - 8% in patients with rs3865444, which is associated with decreased full-length CD33 expression. AAThe non-protective allele is in strong linkage disequilibrium with the variant. The remission rate for the non-protective allele is 68% + / - 15%. Carriers of the protective allele also have a lower risk of relapse and a higher disease-free survival rate. Similarly, patients homozygous for the less variant allele (TT) of rs12459419, which reduces full-length CD33 expression by more than 46%, are more likely to have a favorable disease outcome than carriers of the variants CC and CT (52% vs. 31%), and characteristic blast CD33 expression is significantly lower than in other genotypes. This is even the case in patients treated with anti-CD33 antibodies and toxic calicheamicin-gamma derivatives (Mortland et al., (2013) Clin Cancer Res, 1-8). 2459419, which shows a greater than 25% reduction in full-length CD33 expression, TT Allele carriers and rs12459419 CT Carriers of the allele also show a reduced risk of Alzheimer's disease (Malik M. et al. (2015) Human Molecular Genetics, 1-14), suggesting that reducing CD33 expression or function may be beneficial in Alzheimer's disease and cancer.

[0006] Thus, there is a need for therapeutic anti-CD33 antibodies to treat diseases, disorders, and conditions associated with unwanted CD33 activity.

[0007] All references cited herein, including patents, patent applications, and patent publications, are hereby incorporated by reference in their entirety. Summary of the Invention

[0008] The present disclosure relates generally to compositions comprising antibodies, such as monoclonal, chimeric, humanized antibodies, antibody fragments, etc., that specifically bind to human CD33, and methods of using such compositions.

[0009] Certain aspects of the present disclosure are based, at least in part, on the identification of anti-CD33 antibodies with improved and / or enhanced functional properties (e.g., relative to an anti-CD33 antibody having a heavy chain variable region comprising the sequence of SEQ ID NO: 103 and a light chain variable region comprising the sequence of SEQ ID NO: 104), including, for example, improved and / or enhanced ability to reduce cell surface CD33 levels on human primary immune cells and / or improved and / or enhanced binding kinetics. In some embodiments, the anti-CD33 antibodies of the present disclosure have a K D has a K for human CD33 that is at least 9-fold lower than an anti-CD33 antibody having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77. In some embodiments, the anti-CD33 antibodies of the present disclosure have a K for human CD33 that is at least 9-fold lower than an anti-CD33 antibody having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77. D has a K for human CD33 that is at least 3-fold lower than an anti-CD33 antibody having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86. In some embodiments, the anti-CD33 antibodies of the present disclosure have a K for human CD33 that is at least 3-fold lower than an anti-CD33 antibody having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86. D has an EC2 that is at least 3-fold lower than an anti-CD33 antibody having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 52 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86. In some embodiments, the anti-CD33 antibodies of the present disclosure reduce cell surface CD33 levels in vitro by at least about 50% lower than an anti-CD33 antibody having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77. 50 In some embodiments, the anti-CD33 antibodies of the present disclosure reduce cell surface CD33 levels in vitro with an EC2 that is at least about 10% lower than an anti-CD33 antibody having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86. 50 In some embodiments, the anti-CD33 antibodies of the present disclosure reduce cell surface CD33 levels in vitro with an EC2 that is at least about 10% lower than an anti-CD33 antibody having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 52 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86. 50In some embodiments, the anti-CD33 antibodies of the disclosure have an EC2 that is at least about 10-fold lower than an anti-CD33 antibody having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 103 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 104, as measured by in vitro flow cytometry on the cell surface. 50 Advantageously, the anti-CD33 antibody has a half maximal effective concentration (EC) in the range of about 151.1 pM to about 4.1 pM. 50 ) to reduce cellular levels of CD33 in vitro, bind to human cells (e.g., human primary dendritic cells), and exhibit dissociation constants (K ) for human CD33 ranging from about 8.57 nM to about 202 pM. D )

[0010] Accordingly, in one aspect, the disclosure relates to an antibody that binds to a CD33 protein, the antibody comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises an HVR-H1 comprising a sequence of Formula I: GX1X2X3TDYNX4H (SEQ ID NO: 152), where X1 is Y, A, or V, X2 is T or A, X3 is F, E, or H, and X4 is L, F, Y, or N; an HVR-H2 comprising a sequence of Formula II: FIYPX1NX2IX3G (SEQ ID NO: 153), where X1 is S or A, and X4 is L, F, Y, or N; and HVR-H3 comprising the sequence of Formula III:SX1VDYFDX2 (SEQ ID NO: 154), where X1 is T, D, F, or S and X2 is Y, D, or L, provided that the antibody is not an antibody comprising a heavy chain variable region comprising HVR-H1 comprising the sequence of GYTFTDYNLH (SEQ ID NO: 105), HVR-H2 comprising the sequence of FIYPSNGITG (SEQ ID NO: 115), and HVR-H3 comprising the sequence of STVDYFDY (SEQ ID NO: 121).

[0011] In another aspect, the disclosure relates to an antibody that binds to CD33 protein, the antibody comprising a heavy chain variable region and a light chain variable region, wherein the light chain variable region comprises an HVR-L1 comprising a sequence of Formula IV: X1X2SQX3VX4X5STYSYMH (SEQ ID NO: 155), wherein X1 is R or K, X2 is A, G, or V, X3 is S or D, X4 is S, G, or H, and X5 is T or A; or an HVR-L2 comprising a sequence of Formula V: YX1X2X3X4X5S (SEQ ID NO: 156), wherein X1 is A, V, or E, X2 is S, V, or F, and X3 is N, A, Y, or F. wherein X4 is L or V and X5 is E, G, or N; and an HVR-L3 comprising the sequence of formula VI: X1HSX2X3X4PLX5 (SEQ ID NO: 157), where X1 is Q or E, X2 is W or E, X3 is E or A, X4 is I or L, and X5 is T or E, provided that the antibody is not an antibody comprising a light chain variable region comprising an HVR-L1 comprising the sequence of RASQSVSTSTYSYMH (SEQ ID NO: 127), an HVR-L2 comprising the sequence of YASNLES (SEQ ID NO: 135), and an HVR-L3 comprising the sequence of QHSWEIPLT (SEQ ID NO: 146).

[0012] In another aspect, the disclosure relates to an antibody that binds to CD33 protein, the antibody comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises an HVR-H1 comprising a sequence of Formula I: GX1X2X3TDYNX4H (SEQ ID NO: 152), wherein Xi is Y, A, or V, X2 is T or A, X3 is F, E, or H, and X4 is L, F, Y, or N; an HVR-H2 comprising a sequence of Formula II: FIYPX1NX2IX3G (SEQ ID NO: 153), wherein Xi is S or A, X2 is G, Q, and HVR-H3 comprising a sequence of Formula III: SX1VDYFDX2 (SEQ ID NO: 154), where Xi is T, D, F, or S and X2 is Y, D, or L, wherein the light chain variable region comprises a sequence of Formula IV: X1X2SQX3VX4X5STYSYMH (SEQ ID NO: 155), where Xi is R or K, X2 is A, G, or V, X3 is S or D, X4 is S, G, or H, and X5 is T or A. HVR-L2 comprising a sequence of formula V: YX1X2X3X4X5S (SEQ ID NO: 156), where X1 is A, V, or E, X2 is S, V, or F, X3 is N, A, Y, or F, X4 is L or V, and X5 is E, G, or N; and HVR-L3 comprising a sequence of formula VI: X1HSX2X3X4PLX5 (SEQ ID NO: 157), where X1 is Q or E, X2 is W or E, X3 is E or A, X4 is I or L, and X5 is T or E. wherein the antibody is not an antibody comprising a heavy chain variable region comprising HVR-H1 comprising the sequence GYTFTDYNLH (SEQ ID NO: 105), HVR-H2 comprising the sequence FIYPSNGITG (SEQ ID NO: 115), and HVR-H3 comprising the sequence STVDYFDY (SEQ ID NO: 121), and a light chain variable region comprising HVR-L1 comprising the sequence RASQSVSTSTYSYMH (SEQ ID NO: 127), HVR-L2 comprising the sequence YASNLES (SEQ ID NO: 135), and HVR-L3 comprising the sequence QHSWEIPLT (SEQ ID NO: 146).

[0013] In another aspect, the disclosure relates to antibodies that bind to CD33 protein, the antibodies comprising a heavy chain variable region and a light chain variable region, the heavy chain variable region being selected from the group consisting of antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-63.19, AB-63.20, AB-63.21, AB-63.22, AB-63.23, AB-63.24, AB-63.25, AB-63.26, AB-63.27, AB-63.28, AB-63.29, AB-63.30, AB-63.31, AB-63.32, AB-63.33, AB-63.34, AB-63.35, AB-63.36, AB-63.37, AB-63.38, AB-63.39, AB-63.40, AB-63.41, AB-63.42, AB-63.43, AB-63.44, AB-63.45, AB-63.46, AB-63.47, AB HVR-H1, HVR-H2, and HVR-H3 (as shown in Tables 3A-3C) of AB-63.18, AB-64.1, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15.

[0014] In another aspect, the disclosure relates to an antibody that binds to a CD33 protein, the antibody comprising a heavy chain variable region and a light chain variable region, wherein the light chain variable region is selected from the group consisting of antibodies AB-14.3, AB-14.4, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB- and HVR-L1, HVR-L2, and HVR-L3 (as shown in Tables 4A-4C) of AB-63.10, AB-63.11, AB-63.12, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, or AB-64.8.

[0015] In another aspect, the disclosure relates to an antibody that binds to a CD33 protein, the antibody comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region is selected from the group consisting of antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.8, AB-63.9, AB-63.10, AB- 63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.3, AB-64.4, AB-64.5 , AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64. and the light chain variable region comprises the HVR-H1, HVR-H2, and HVR-H3 (as set forth in Tables 3A-3C) of antibodies AB-14.3, AB-14.4, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15. HVR-L1, HVR-L2, and HVR-L3 of AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, or AB-64.8 (as shown in Tables 4A-4C).

[0016] In another aspect, the disclosure relates to an antibody that binds to CD33 protein, the antibody comprising a heavy chain variable region comprising HVR-H1, HVR-H2, and HVR-H3 and a light chain variable region comprising HVR-L1, HVR-L2, and HVR-L3, the antibody being selected from antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-14.12, AB-14.13, AB-14.14, AB-14.15, AB-14.16, AB-14.17, AB-14.18, AB-14.19, AB-14.20, AB-14.21, AB-14.22, AB-14.23, AB-14.24, AB-14.25, AB-14.26, AB-14.27, AB-14.28, AB-14.29, AB-14.30, AB-14.31, AB-14.32, AB-14.33, AB-14.34, AB-14.35, AB-14.36, AB-14.37, AB-14.38, AB-14.39, AB-14.40, AB-14.41, AB-14.42, AB-14.43, AB-14.44, AB-14.45, AB-14.46, AB-14.47, AB-14.48, AB-14.49, -14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63. 7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63. 16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, A B-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, A Including HVR-H1, HVR-H2, HVR-H3, HVR-L1, HVR-L2, and HVR-L3 (as shown in Tables 3A-3C and Tables 4A-4C) of B-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15.

[0017] Another aspect of the present disclosure relates to an antibody that binds to CD33 protein, the antibody comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises the Kabat CDRs and / or the light chain variable region comprises the Kabat CDRs. In some embodiments, the heavy chain variable region comprises CDR-H1 comprising the sequence of DYNLH (SEQ ID NO: 190), CDR-H2 comprising the sequence of FIYPSNGITGYAQKFQ (SEQ ID NO: 194), and CDR-H3 comprising the sequence of YCARSDVD (SEQ ID NO: 191). In some embodiments, the light chain variable region comprises CDR-L1 comprising the sequence of RASQSVSTSTYSYMH (SEQ ID NO: 127), CDR-L2 comprising the sequence of LLIKYAS (SEQ ID NO: 192), and CDR-L3 comprising the sequence of VYYCQHSWE (SEQ ID NO: 193). In some embodiments, the heavy chain variable region comprises CDR-H1 comprising the sequence of DYNLH (SEQ ID NO: 190), CDR-H2 comprising the sequence of FIYPSNGITGYAQKFQ (SEQ ID NO: 194), and CDR-H3 comprising the sequence of YCARSDVD (SEQ ID NO: 191), and the light chain variable region comprises CDR-L1 comprising the sequence of RASQSVSTSTYSYMH (SEQ ID NO: 127), CDR-L2 comprising the sequence of LLIKYAS (SEQ ID NO: 192), and CDR-L3 comprising the sequence of VYYCQHSWE (SEQ ID NO: 193).

[0018] Another aspect of the present disclosure relates to an antibody that binds to a CD33 protein, the antibody comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises the Kabat CDRs and / or the light chain variable region comprises the Kabat CDRs. In some embodiments, the heavy chain variable region comprises a CDR-H1 comprising the sequence of DYNLH (SEQ ID NO: 190), a CDR-H2 comprising the sequence of FIYPSNRITGYAQKFQ (SEQ ID NO: 195), and a CDR-H3 comprising the sequence of YCARSDVD (SEQ ID NO: 191). In some embodiments, the light chain variable region comprises a CDR-L1 comprising the sequence of RASQSVSTSTYSYMH (SEQ ID NO: 127), a CDR-L2 comprising the sequence of LLIKYAS (SEQ ID NO: 192), and a CDR-L3 comprising the sequence of VYYCQHSWE (SEQ ID NO: 193). In some embodiments, the heavy chain variable region comprises CDR-H1 comprising the sequence of DYNLH (SEQ ID NO: 190), CDR-H2 comprising the sequence of FIYPSNRITGYAQKFQ (SEQ ID NO: 195), and CDR-H3 comprising the sequence of YCARSDVD (SEQ ID NO: 191), and the light chain variable region comprises CDR-L1 comprising the sequence of RASQSVSTSTYSYMH (SEQ ID NO: 127), CDR-L2 comprising the sequence of LLIKYAS (SEQ ID NO: 192), and CDR-L3 comprising the sequence of VYYCQHSWE (SEQ ID NO: 193).

[0019] Another aspect of the present disclosure relates to an antibody that binds to a CD33 protein, the antibody comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises the Kabat CDRs and / or the light chain variable region comprises the Kabat CDRs. In some embodiments, the heavy chain variable region comprises a CDR-H1 comprising the sequence of DYNLH (SEQ ID NO: 190), a CDR-H2 comprising the sequence of FIYPSNQITGYAQKFQ (SEQ ID NO: 196), and a CDR-H3 comprising the sequence of YCARSDVD (SEQ ID NO: 191). In some embodiments, the light chain variable region comprises a CDR-L1 comprising the sequence of RASQSVSTSTYSYMH (SEQ ID NO: 127), a CDR-L2 comprising the sequence of LLIKYAS (SEQ ID NO: 192), and a CDR-L3 comprising the sequence of VYYCQHSWE (SEQ ID NO: 193). In some embodiments, the heavy chain variable region comprises CDR-H1 comprising the sequence of DYNLH (SEQ ID NO: 190), CDR-H2 comprising the sequence of FIYPSNQITGYAQKFQ (SEQ ID NO: 196), and CDR-H3 comprising the sequence of YCARSDVD (SEQ ID NO: 191), and the light chain variable region comprises CDR-L1 comprising the sequence of RASQSVSTSTYSYMH (SEQ ID NO: 127), CDR-L2 comprising the sequence of LLIKYAS (SEQ ID NO: 192), and CDR-L3 comprising the sequence of VYYCQHSWE (SEQ ID NO: 193).

[0020] In some embodiments that may be combined with any of the preceding embodiments, the heavy chain variable region comprises one, two, three, or four framework regions selected from VH FR1, VH FR2, VH FR3, and VH FR4, wherein VH FR1 comprises a sequence of Formula VII: QVQLVQSGAEVKKPGX1SVKX2SCKAS (SEQ ID NO: 158), where X1 is A or S and X2 is V or I; VH FR2 comprises a sequence of SEQ ID NO: 5; and VH FR3 comprises a sequence of Formula VIII: X1AX2X3X4X5X6RX7TX8TVDX9X 10 X 11 STX 12X is Y or S, X is Q or E, X is K or D, X is F or D, X is Q, F, E, or T, X is G, D, or H, X is V or A, X is M or L, X is T, N, or Q, and X is G, D, or H. 10 is S or P, and X 11 is T or A, and X 12 is V or A, VH FR4 comprises a sequence of formula IX:WGQGTLX1TVSS (SEQ ID NO: 160), where X1 is V or L, and / or the light chain comprises one, two, three, or four framework regions selected from VL FR1, VL FR2, VL FR3, and VL FR4, where VL FR1 has the formula X:X1IX2X3TQSPX4SLX5X6SX7GX8RX9TIX 10 X1 is D or G, X2 is Q or V, X3 is M or L, X4 is S or D, X5 is S, P, or A, X6 is A or V, X7 is V or L, X8 is D or E, X9 is V or A, and X 10is T, N, or D; VL FR2 comprises the sequence of formula XI: WYQQKPGX1X2PKLLIK (SEQ ID NO: 162), where X1 is K or Q, and X2 is A or P; VL FR3 comprises the sequence of formula XII: GVPX1RFSGSGSGTDFTLTISSLQX2EDX3AX4YYC (SEQ ID NO: 163), where X1 is S or D, X2 is P or A, X3 is F, L, or V, and X4 is T or V; and VL FR4 comprises the sequence of formula XIII: FGQGTKLEIX1 (SEQ ID NO: 164), where X1 is K or E. In some embodiments that may be combined with any of the preceding embodiments, the heavy chain variable region comprises one, two, three, or four framework regions selected from VH FR1, VH FR2, VH FR3, and VH FR4, where VH FR1 comprises a sequence selected from the group consisting of SEQ ID NOs: 2-4, VH FR2 comprises the sequence of SEQ ID NO: 5, VH FR3 comprises a sequence selected from the group consisting of SEQ ID NOs: 6-19, and VH FR4 comprises a sequence selected from the group consisting of SEQ ID NOs: 20-21; and / or the light chain comprises one, two, three, or four framework regions selected from VL FR1, VL FR2, VL FR3, and VL FR4, where VL FR1 comprises a sequence selected from the group consisting of SEQ ID NOs: 22-26, VL FR2 comprises a sequence selected from the group consisting of SEQ ID NOs: 27-28, and VL FR3 comprises a sequence selected from the group consisting of SEQ ID NOs: 29-31. FR4 comprises a sequence selected from the group consisting of SEQ ID NOs: 32-33.

[0021] In some embodiments that may be combined with any of the preceding embodiments, the antibody comprises a heavy chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 34-72, and / or a light chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 77-101.In some embodiments, the antibody is antibody AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, the heavy chain variable region of AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 (as shown in Table 7) and / or the antibody is selected from the group consisting of antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB- AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 light chain variable region (as shown in Table 8).In some embodiments that may be combined with any of the preceding embodiments, the HVR-H1 comprises the amino acid sequence GYTFTDYNLH (SEQ ID NO: 105), the HVR-H2 comprises the amino acid sequence FIYPSNRITG (SEQ ID NO: 119), the HVR-H3 comprises the amino acid sequence SDVDYFDY (SEQ ID NO: 122), the HVR-L1 comprises the amino acid sequence RASQSVSTSTYSYMH (SEQ ID NO: 127), the HVR-L2 comprises the amino acid sequence YASNLES (SEQ ID NO: 135), and the HVR-L3 comprises the amino acid sequence QHSWEIP LT (SEQ ID NO: 146), or wherein the HVR-H1 comprises the amino acid sequence GYTFTDYNLH (SEQ ID NO: 105), the HVR-H2 comprises the amino acid sequence FIYPSNQITG (SEQ ID NO: 118), the HVR-H3 comprises the amino acid sequence SDVDYFDY (SEQ ID NO: 122), the HVR-L1 comprises the amino acid sequence RASQSVSTSTYSYMH (SEQ ID NO: 127), the HVR-L2 comprises the amino acid sequence YASNLES (SEQ ID NO: 135), and the HVR-L3 comprises the amino acid sequence QHSWEIPLT (SEQ ID NO: 146).

[0022] In another aspect, the disclosure relates to an antibody that binds to a CD33 protein, the antibody comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises HVR-H1 comprising the amino acid sequence GYTFTDYNLH (SEQ ID NO: 105), HVR-H2 comprising the amino acid sequence FIYPSNRITG (SEQ ID NO: 119), and HVR-H3 comprising the amino acid sequence SDVDYFDY (SEQ ID NO: 122); and the light chain variable region comprises HVR-L1 comprising the amino acid sequence RASQSVSTSTYSYMH (SEQ ID NO: 127), HVR-L2 comprising the amino acid sequence YASNLES (SEQ ID NO: 135), and HVR-L3 comprising the amino acid sequence QHSW or the heavy chain comprises an HVR-H1 comprising the amino acid sequence GYTFTDYNLH (SEQ ID NO: 105), an HVR-H2 comprising the amino acid sequence FIYPSNQITG (SEQ ID NO: 118), and an HVR-H3 comprising the amino acid sequence SDVDYFDY (SEQ ID NO: 122), and the light chain variable region comprises an HVR-L1 comprising the amino acid sequence RASQSVSTSTYSYMH (SEQ ID NO: 127), an HVR-L2 comprising the amino acid sequence YASNLES (SEQ ID NO: 135), and an HVR-L3 comprising the amino acid sequence QHSWEIPLT (SEQ ID NO: 146).

[0023] In another aspect, the present disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 34-72 and / or a light chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 77-101.In some embodiments, the antibody is antibody AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, the heavy chain variable region of AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 (as shown in Table 7) and / or the antibody is selected from the group consisting of antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB- AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 light chain variable region (as shown in Table 8).In some embodiments, the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:59 and / or the light chain variable region comprises the amino acid sequence of SEQ ID NO:86, or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:65 and / or the light chain variable region comprises the amino acid sequence of SEQ ID NO:86.

[0024] In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 34, 40, 42, 52, 53, and 73-76, and / or a light chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 77, 86, and 102. In some embodiments, the antibody comprises the heavy chain variable region of AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, or AB-H66 (as shown in Table 7), and / or the antibody comprises the light chain variable region of antibody AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, or AB-H66 (as shown in Table 8).

[0025] In another aspect, the present disclosure relates to antibodies that bind to CD33 protein, the antibodies being selected from the group consisting of AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB- and any combination thereof.

[0026] In another aspect, the present disclosure relates to antibodies that bind to CD33 protein, the antibodies being selected from the group consisting of AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB- and AB-H63, AB-H64, AB-H65, AB-H66, and AB-H67.

[0027] In another aspect, the disclosure relates to antibodies that bind to CD33 protein, the antibodies comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region includes an HVR-H1 comprising the sequence of Formula I: GX1X2X3TDYNX4H (SEQ ID NO: 186), wherein Xi is Y or V, X2 is T or A, X3 is F, E, or H, and X4 is L, F, Y, or N; an HVR-H2 comprising the sequence of Formula II: FIYPX1NX2IX3G (SEQ ID NO: 153), wherein Xi is S or A, X2 is G, Q, R, or V, and X3 is T or R; and an HVR-H3 comprising the sequence of Formula III: SX1VDYFDX2 (SEQ ID NO: 187), wherein Xi is T, D, or F, and X2 is Y, D, or L; IV: HVR-L1 comprising a sequence of formula XIX2SQX3VX4X5STYSYMH (SEQ ID NO: 188), wherein X1 is R or K, X2 is A, G, or V, X3 is S or D, X4 is S, G, or H, and X5 is T; V: HVR-L2 comprising a sequence of formula V: YX1X2X3X4X5S (SEQ ID NO: 189), wherein X1 is A or E; and HVR-L3 comprising a sequence of formula VI: X1HSX2X3X4PLX5 (SEQ ID NO: 157), wherein X1 is Q or E, X2 is W or E, X3 is E or A, X4 is I or L, and X5 is T or E.

[0028] In another aspect, the present disclosure relates to an antibody that binds to CD33 protein, the antibody comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises HVR-H1 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 105 and 108-114, HVR-H2 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 115-120, and HVR-H3 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 121-123 and 125-126, and the light chain variable region comprises HVR-L1 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 127-128 and 130-134, HVR-L2 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 135 and 140-145, and HVR-L3 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 146-151.

[0029] In some embodiments that may be combined with any of the preceding embodiments, the heavy chain variable region comprises one, two, three, or four framework regions selected from VH FR1, VH FR2, VH FR3, and VH FR4, wherein VH FR1 comprises a sequence of Formula VII: QVQLVQSGAEVKKPGX1SVKX2SCKAS (SEQ ID NO: 158), where X1 is A or S and X2 is V or I; VH FR2 comprises a sequence of SEQ ID NO: 5; and VH FR3 comprises a sequence of Formula VIII: X1AX2X3X4X5X6RX7TX8TVDX9X 10 X 11 STX 12 X is Y or S, X is Q or E, X is K or D, X is F or D, X is Q, F, E, or T, X is G, D, or H, X is V or A, X is M or L, X is T, N, or Q, and X is G, D, or H. 10 is S or P, and X 11 is T or A, and X 12is V or A, VH FR4 comprises a sequence of formula IX:WGQGTLX1TVSS (SEQ ID NO: 160), where X1 is V or L, and / or the light chain comprises one, two, three, or four framework regions selected from VL FR1, VL FR2, VL FR3, and VL FR4, where VL FR1 has the formula X:X1IX2X3TQSPX4SLX5X6SX7GX8RX9TIX 10 X1 is D or G, X2 is Q or V, X3 is M or L, X4 is S or D, X5 is S, P, or A, X6 is A or V, X7 is V or L, X8 is D or E, X9 is V or A, and X 10 is T, N, or D; VL FR2 comprises the sequence of formula XI: WYQQKPGX1X2PKLLIK (SEQ ID NO: 162), where X1 is K or Q, and X2 is A or P; VL FR3 comprises the sequence of formula XII: GVPX1RFSGSGSGTDFTLTISSLQX2EDX3AX4YYC (SEQ ID NO: 163), where X1 is S or D, X2 is P or A, X3 is F, L, or V, and X4 is T or V; and VL FR4 comprises the sequence of formula XIII: FGQGTKLEIX1 (SEQ ID NO: 164), where X1 is K or E.

[0030] In some embodiments that may be combined with any of the preceding embodiments, the heavy chain variable region comprises one, two, three, or four framework regions selected from VH FR1, VH FR2, VH FR3, and VH FR4, where VH FR1 comprises a sequence selected from the group consisting of SEQ ID NOs: 2-4, VH FR2 comprises the sequence of SEQ ID NO: 5, VH FR3 comprises a sequence selected from the group consisting of SEQ ID NOs: 6-19, and VH FR4 comprises a sequence selected from the group consisting of SEQ ID NOs: 20-21; and / or the light chain comprises one, two, three, or four framework regions selected from VL FR1, VL FR2, VL FR3, and VL FR4, where VL FR1 comprises a sequence selected from the group consisting of SEQ ID NOs: 22-26, VL FR2 comprises a sequence selected from the group consisting of SEQ ID NOs: 27-28, and VL FR3 comprises a sequence selected from the group consisting of SEQ ID NOs: 29-31. FR4 comprises a sequence selected from the group consisting of SEQ ID NOs: 32 to 33. In some embodiments that may be combined with any of the preceding embodiments, the heavy chain variable region comprises a VH FR3 comprising a sequence selected from the group consisting of SEQ ID NOs: 12 to 15.

[0031] In another aspect, the present disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 38 and 40-72, and / or a light chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 86-101.

[0032] In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:58 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:86; a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:59 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:86; a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:65 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:86; a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:66 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:86; a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:67 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:86; a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:68 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:86; or a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:69 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:86.

[0033] In some embodiments that may be combined with any of the preceding embodiments, the antibody is of the IgG class, the IgM class, or the IgA class. In some embodiments, the antibody is of the IgG class and has an IgG1, IgG2, IgG3, or IgG4 isotype. In some embodiments, the antibody has an IgG4 isotype and comprises an amino acid substitution of S228P at residue position 228, an amino acid substitution of F234A at residue position 234, and an amino acid substitution of L235A at residue position 235. The numbering of the residue positions is according to EU numbering. In some embodiments, the antibody comprises one or more amino acid substitutions in the Fc region at residue positions selected from the group consisting of C127S, L234A, L234F, L235A, L235E, S267E, K322A, L328F, A330S, P331S, E345R, E430G, S440Y, and any combination thereof, wherein the numbering of the residues is according to EU or Kabat numbering.In some embodiments, the Fc region comprises an amino acid substitution at position E430G, where the numbering of residue positions is according to EU numbering; the Fc region comprises amino acid substitutions at positions L243A, L235A, and P331A, where the numbering of residue positions is according to EU numbering; the Fc region comprises amino acid substitutions at positions L243A, L235A, P331A, and E430G, where the numbering of residue positions is according to EU numbering; or the Fc region comprises amino acid substitutions at positions K322A and E430G according to EU numbering; or the Fc region comprises amino acid substitutions at positions P331S and E430G wherein the numbering of residue positions is according to EU numbering; or the Fc region comprises amino acid substitutions at positions A330S, P331S, and E430G wherein the numbering of residue positions is according to EU numbering; or the Fc region comprises amino acid substitutions at positions K322A, A330S, and P331S wherein the numbering of residue positions is according to EU numbering. the Fc region comprises amino acid substitutions at positions K322A, P331S, and E430G, where the numbering of the residue positions is according to EU numbering; the Fc region comprises amino acid substitutions at position E430G, where the numbering of the residue positions is according to EU numbering; the Fc region comprises amino acid substitutions at positions A330S, P331S, and E430G, where the numbering of the residue positions is according to EU numbering; or the Fc region comprises amino acid substitutions at positions S267E and L328F, or the Fc region comprises an amino acid substitution at position C127S, where the numbering of residue positions is according to EU numbering, or the Fc region comprises amino acid substitutions at positions E345R, E430G, and S440Y, where the numbering of residue positions is according to EU numbering, or the Fc region comprises amino acid substitutions at positions L243A, L235A, and P331S, where the numbering of residue positions is according to EU numbering.

[0034] In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 176 and a light chain comprising the amino acid sequence of SEQ ID NO: 185. In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 177 and a light chain comprising the amino acid sequence of SEQ ID NO: 185. In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 178 and a light chain comprising the amino acid sequence of SEQ ID NO: 185. In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 179 and a light chain comprising the amino acid sequence of SEQ ID NO: 185. In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 180 and a light chain comprising the amino acid sequence of SEQ ID NO: 185. In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 181 and a light chain comprising the amino acid sequence of SEQ ID NO: 185. In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 182 and a light chain comprising the amino acid sequence of SEQ ID NO: 185. In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 183 and a light chain comprising the amino acid sequence of SEQ ID NO: 185. In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 184 and a light chain comprising the amino acid sequence of SEQ ID NO: 185. In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 197 and a light chain comprising the amino acid sequence of SEQ ID NO: 185. In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 198 and a light chain comprising the amino acid sequence of SEQ ID NO: 185. In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 199 and a light chain comprising the amino acid sequence of SEQ ID NO: 185.In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 200 and a light chain comprising the amino acid sequence of SEQ ID NO: 185. In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 201 and a light chain comprising the amino acid sequence of SEQ ID NO: 185. In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 202 and a light chain comprising the amino acid sequence of SEQ ID NO: 185. In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 203 and a light chain comprising the amino acid sequence of SEQ ID NO: 185. In another aspect, the disclosure relates to an antibody that binds to CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 204 and a light chain comprising the amino acid sequence of SEQ ID NO: 185. In another aspect, the disclosure relates to an antibody that binds to a CD33 protein, wherein the antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 205 and a light chain comprising the amino acid sequence of SEQ ID NO: 185.

[0035] In some embodiments that may be combined with any of the preceding embodiments, the CD33 protein is a mammalian protein or a human protein. In some embodiments, the CD33 protein is a wild-type protein. In some embodiments, the CD33 protein is a naturally occurring variant. In some embodiments that may be combined with any of the preceding embodiments, the CD33 protein is expressed on one or more cells selected from the group consisting of human dendritic cells, human macrophages, human monocytes, human osteoclasts, human neutrophils, human T cells, human T helper cells, human cytotoxic T cells, human granulocytes, and human microglia.

[0036] In some embodiments that may be combined with any of the preceding embodiments, the antibody specifically binds to human CD33 protein. In some embodiments, the antibody binds to human CD33 protein and does not cross-react with CD33 orthologs or homologs from other species. In some embodiments that may be combined with any of the preceding embodiments, the antibody is an antibody fragment that binds to an epitope comprising amino acid residues of human CD33 or a mammalian CD33 protein. In some embodiments that may be combined with any of the preceding embodiments, the antibody is an antibody fragment that binds to one or more human proteins selected from the group consisting of human CD33, naturally occurring variants of human CD33, and disease variants of human CD33. In some embodiments, the antibody fragment is crosslinked to a second antibody fragment that binds to one or more human proteins selected from the group consisting of human CD33, naturally occurring variants of human CD33, and disease variants of human CD33. In some embodiments, the fragment is a Fab, Fab', Fab'-SH, F(ab')2, Fv, or scFv fragment.

[0037] In some embodiments that may be combined with any of the preceding embodiments, the antibody is a humanized antibody, a bispecific antibody, a monoclonal antibody, a multivalent antibody, a conjugated antibody, or a chimeric antibody. In some embodiments, the antibody is a monoclonal antibody. In some embodiments, the antibody is a bispecific antibody that recognizes a first antigen and a second antigen. In some embodiments, the first antigen is CD33 and the second antigen is an antigen that facilitates transport across the blood-brain barrier, transferrin receptor (TR), insulin receptor (HIR), insulin-like growth factor receptor (IGFR), low-density lipoprotein receptor-related proteins 1 and 2 (LPR-1 and 2), diphtheria toxin receptor, CRM197, llama single domain antibody, TMEM 30(A), a protein transduction domain, TAT, Syn-B, penetratin, a polyarginine peptide, an angiopep peptide, and ANG1005, and a pathogen selected from the group consisting of an antigen, a pathogenic peptide or protein, and a pathogenic nucleic acid that promotes transport across the blood-brain barrier, wherein the pathogenic peptide or protein is amyloid beta, oligomeric amyloid beta, amyloid beta plaque, amyloid precursor protein or a fragment thereof, tau, IAPP, alpha-synuclein, TDP-43, FUS protein, C9orf72 (chromosome 9 open reading frame 72), c9RAN protein, a prion protein, PrPSc, huntingtin, calcitonin. , superoxide dismutase, ataxin, ataxin 1, ataxin 2, ataxin 3, ataxin 7, ataxin 8, ataxin 10, Lewy bodies, atrial natriuretic factor, islet amyloid polypeptide, insulin, apolipoprotein AI, serum amyloid A, medin, prolactin, transthyretin, lysozyme, beta-2 microglobulin, gelsolin, keratoepithelin, cystatin, immunoglobulin light chain AL, S-IBM protein, repeat-associated non-ATG (RAN) translation products, dipeptide repeat (DPR) peptides, glycine-alanine (GA) repeat peptides, glycine-proline (GP) repeat peptides, glycine-arginine (GR) repeat peptides, proline-alanine (PA) repeat peptides, ubiquitin,and proline-arginine (PR) repeat peptides, wherein the pathogen nucleic acid is an antisense GGCCCC (G2C4) repeat expansion RNA. Pathogens, immune cell-expressed ligands and / or proteins, including CD40, OX40, ICOS, CD28, CD137 / 4-1BB, CD27, GITR, PD-L1, CTLA4, PD-L2, PD-1, B7-H3, B7-H4, HVEM, LIGHT, BTLA, CD38, TIGIT , VISTA, KIR, GAL9, TIM1, TIM3, TIM4, A2AR, LAG3, DR5, CD39, CD70, CD73, TREM1, TREM2, Siglec-5, Siglec-7, Siglec-9, Siglec-11, SirpA, CD47, CSF1 receptor, and phosphatidylserine, and a ligand and / or protein selected from the group consisting of a protein, lipid, polysaccharide, or glycolipid expressed in one or more tumor cells.

[0038] In some embodiments that may be combined with any of the preceding embodiments, the antibody is selected from the group consisting of a pathogenic peptide, a pathogenic protein, amyloid beta, oligomeric amyloid beta, amyloid beta plaques, amyloid precursor protein or fragments thereof, tau, IAPP, alpha-synuclein, TDP-43, FUS protein, C9orf72 (chromosome 9 open reading frame 72), prion protein, PrPSc, huntingtin, calcitonin, superoxide dismutase, ataxin, ataxin 1, and ataxin 2. , ataxin 3, ataxin 7, ataxin 8, ataxin 10, Lewy bodies, atrial natriuretic factor, islet amyloid polypeptide, insulin, apolipoprotein AI, serum amyloid A, medin, prolactin, transthyretin, lysozyme, beta-2 microglobulin, gelsolin, keratoepithelin, cystatin, immunoglobulin light chain AL, S-IBM protein, repeat-associated non-ATG (RAN) translation products, dipeptide repeat (DPR) peptides, glycine-alanine (GA) repeat peptides, glycine-pro and / or in combination with one or more antibodies that specifically bind to a pathogen selected from the group consisting of: phospholipid (GP) repeat peptides, glycine-arginine (GR) repeat peptides, proline-alanine (PA) repeat peptides, ubiquitin, and proline-arginine (PR) repeat peptides, and any combination thereof; or CD40, OX40, ICOS, CD28, CD137 / 4-1BB, CD27, GITR, PD-L1, CTLA4, PD-L2, PD-1, B7-H3, B7-H4, HVEM, LIGHT, BTLA, CD3 8, TIGIT, VISTA, KIR, GAL9, TIM1, TIM3, TIM4, A2AR3, DR5, CD39, CD70, CD73, LAG3, TREM1, TREM2, Siglec-5, Siglec-7, Siglec-9, Siglec-11, SirpA, CD47, CSF1 receptor, phosphatidylserine, pathogenic nucleic acid, antisense GGCCCC (G2C4) repeat expansion RNA, and any combination thereof.

[0039] In some embodiments that may be combined with any of the preceding embodiments, the antibody has a dissociation constant (K D ) is at least 4-fold lower than that of an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77, or at least 1-fold lower than that of an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, or at least 1-fold lower than that of an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 52 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, in which case the K D is measured by surface plasmon resonance. In some embodiments that may be combined with any of the preceding embodiments, the antibody has a dissociation constant (K D ) is in the range of about 2 nM to about 200 pM, or less than about 200 pM, in which case the K D is measured by BioLayer interferometry.

[0040] In some embodiments that may be combined with any of the preceding embodiments, the antibody reduces cell surface CD33 levels. In some embodiments, the CD33 is expressed on the surface of human dendritic cells. In some embodiments, the antibody reduces cell surface CD33 levels in vitro. In some embodiments, the antibody reduces cell surface CD33 levels in vitro, as measured by flow cytometry, at a half maximal effective concentration (EC) of less than 150 pM. 50In some embodiments, the antibody reduces cell surface CD33 levels in vitro as measured by flow cytometry, and has an EC that is at least about 50% lower than that of an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77, at least about 10% lower than that of an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, at least about 10% lower than that of an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 52 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, or at least about 10-fold lower than that of an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 103 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 104. 50 Decreases by.

[0041] In another aspect, the disclosure pertains to an isolated nucleic acid comprising a nucleic acid sequence encoding any of the antibodies described herein.

[0042] In another aspect, the disclosure relates to a vector comprising any of the nucleic acids described herein. In some embodiments, the vector is an expression vector and / or a display vector.

[0043] In another aspect, the disclosure relates to an isolated host cell comprising any of the nucleic acids or vectors described herein.

[0044] In another aspect, the disclosure relates to a method for producing an antibody that binds to CD33, comprising culturing any of the host cells described herein to produce the antibody, hi some embodiments, the method further comprises recovering the antibody produced by the cell.

[0045] In another aspect, the disclosure relates to an antibody produced by any of the methods described herein.

[0046] In another aspect, the present disclosure relates to a pharmaceutical composition comprising any of the antibodies described herein and a pharmaceutically acceptable carrier. In some embodiments, the present disclosure relates to the use of any of the antibodies described herein for the preparation of a medicament.

[0047] In another aspect, the present disclosure relates to a method for preventing, reducing the risk of, or treating a disease, disorder, or injury selected from the group consisting of dementia, frontotemporal dementia, Alzheimer's disease, vascular dementia, mixed dementia, taupathies, infectious diseases, and cancer, comprising administering a therapeutically effective amount of any of the antibodies described herein to an individual in need thereof. In some embodiments, the disease, disorder, or injury is cancer. In some embodiments, the cancer is selected from the group consisting of bladder cancer, brain cancer, breast cancer, colon cancer, rectal cancer, endometrial cancer, kidney cancer, renal cell carcinoma, renal pelvis cancer, leukemia, lung cancer, melanoma, non-Hodgkin's lymphoma, pancreatic cancer, prostate cancer, ovarian cancer, fibrosarcoma, acute lymphocytic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), chronic myeloid leukemia (CML), and multiple myeloma. In some embodiments, the disclosure relates to the use of any of the antibodies described herein for the preparation of a medicament useful for preventing, reducing the risk of, or treating a disease, disorder, or injury selected from the group consisting of dementia, frontotemporal dementia, Alzheimer's disease, vascular dementia, mixed dementia, taupathies, infectious diseases, and cancer. In some embodiments, the disease, disorder, or injury is cancer. In some embodiments, the cancer is selected from the group consisting of bladder cancer, brain cancer, breast cancer, colon cancer, rectal cancer, endometrial cancer, kidney cancer, renal cell carcinoma, renal pelvis cancer, leukemia, lung cancer, melanoma, non-Hodgkin's lymphoma, pancreatic cancer, prostate cancer, ovarian cancer, fibrosarcoma, acute lymphocytic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), chronic myeloid leukemia (CML), and multiple myeloma. [Brief explanation of the drawings]

[0048] [Figure 1]1 shows the results of a flow cytometry assay measuring CD33 levels on the surface of primary human monocyte-derived dendritic cells after treatment with a humanized CD33 antibody. [Figure 2] 1 shows the results of flow cytometry measuring CD33 levels on the surface of primary human monocyte-derived dendritic cells after incubation with different concentrations of affinity-matured CD33 antibodies. [Figure 3] 1 shows the results of a ligand blocking assay in which red blood cells containing sialic acid ligands for CD33 are assessed for their ability to bind to CD33 in the presence of different concentrations of CD33 antibody. [Figure 4] 1 shows the results of a flow cytometry assay measuring CD33 levels on the surface of primary human monocyte-derived dendritic cells after treatment with different concentrations of CD33 antibodies containing different Fc regions. [Figure 5] 1 shows the results of flow cytometry measuring human CD33 levels on the surface of huCD45+huCD14+ cells in humanized NSG mice injected with CD33 antibody. [Figure 6] Figure 6A shows the results of flow cytometry assays measuring human CD33 levels on the surface of circulating CD11b+Gr1+ cells in human CD33 transgenic mice injected with a CD33 antibody, and Figure 6B shows the results of flow cytometry assays measuring human CD33 levels on the surface of blood or spleen CD11b+Gr1+ cells in human CD33 transgenic mice injected with a CD33 antibody. [Figure 7] 1 shows the results of an assay measuring the ADCC activity of a CD33 antibody. [Figure 8] 1 shows the results of a CDC assay in the presence of CD33 antibody. [Figure 9-1]Figure 9 shows the results of flow cytometry measuring human CD33 and human Siglec-7 levels on the cell surface in human CD33 and human Siglec-7 transgenic mice after treatment with different concentrations of CD33 antibody. Figure 9A shows human CD33 levels on the surface of microglia, Figure 9B shows human Siglec-7 levels on the surface of microglia, Figure 9C shows human CD33 levels on the surface of circulating neutrophils, and Figure 9D shows human CD33 levels on the surface of circulating monocytes. [Figure 9-2] Figure 9 shows the results of flow cytometry measuring human CD33 and human Siglec-7 levels on the cell surface in human CD33 and human Siglec-7 transgenic mice after treatment with different concentrations of CD33 antibody. Figure 9A shows human CD33 levels on the surface of microglia, Figure 9B shows human Siglec-7 levels on the surface of microglia, Figure 9C shows human CD33 levels on the surface of circulating neutrophils, and Figure 9D shows human CD33 levels on the surface of circulating monocytes. DETAILED DESCRIPTION OF THE INVENTION

[0049] General method The techniques and procedures described or referenced herein are generally well understood and commonly used by those of skill in the art using conventional methods, e.g., Sambrook et al., Molecular Cloning: A Laboratory Manual 3rd edition (2001) Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, Current Protocols in Molecular Biology (F.M.A.usubel, et al. eds., (2003)), series Methods in Enzymology (Academic Press, Inc.): PCR 2: A Practical Approach (M.J. MacPherson, B.D. Hames and G.R. Tayl, eds. (1995)), Harlow and Lane, eds. (1988) Antibodies, A Laboratory Manual, and Animal Cell Culture (R.I. Freshney, ed. (1987)), Oligonucleotide Synthesis (M.J. Gait, ed., 1984), Methods in Molecular Biology, Humana Press, Cell Biology: A Laboratory Manual. Notebook (JECellis, ed., 1998) Academic Press, Animal Cell Culture (RIFreshney), ed., 1987), Introduction to Cell and Tissue Culture (JP Mather and PE Roberts, 1998) Plenum Press, Cell and Tissue Culture: Laboratory Procedures (A. Doyle, JBGriffiths, and DG Newell, eds., 1993-8) J. Wiley and Sons, Handbook of Experimental Immunology (DM Weir and CC Blackwell, eds.), Gene Transfer Vectors for Mammalian Cells (JMMiller and MPCalos, eds., 1987), PCR: The Polymerase Chain Reaction, (Mullis et al., eds., 1994), Current Protocols in Immunology (JEColigan et al., eds., 1991), Short Protocols in Molecular Biology (Wiley and Sons, 1999), Immunobiology (CA Janeway and P. Travers, 1997), Antibodies (P. Finch, 1997), Antibodies: A Practical Approach (D. Catty., ed., IRL Press, 1988-1989), Monoclonal Antibodies: A Practical Approach (P. Shepherd and C. Dean, eds., Oxford University Press, 2000), Using Antibodies: A Laboratory Manual (E.Harlow and These include widely used methods described in D. Lane (Cold Spring Harbor Laboratory Press, 1999), The Antibodies (M. Zanetti and JD Capra, eds., Harwood Academic Publishers, 1995), and Cancer: Principles and Practice of Oncology (VT DeVita et al., eds., J.B. Lippincott Company, 1993).

[0050] definition As used herein, the term "prophylaxis" includes providing protection against the onset or recurrence of a particular disease, disorder, or condition in an individual who may be predisposed to, susceptible to, or at risk of developing such a disease, disorder, or condition, but who has not yet been diagnosed with the disease, disorder, or condition.

[0051] As used herein, an individual "at risk" of developing a particular disease, disorder, or condition may or may not have detectable disease or disease symptoms, and may or may not have exhibited detectable disease or disease symptoms prior to the treatment methods described herein. "At risk" means that an individual has one or more risk factors, which are measurable parameters that correlate with the development of a particular disease, disorder, or condition, as known in the art. Individuals who have one or more of these risk factors have a higher probability of developing a particular disease, disorder, or condition than individuals who do not have one or more of these risk factors.

[0052] As used herein, the term "treatment" refers to a clinical intervention designed to modify the natural course of a treated individual during the course of clinical pathology. Desirable effects of treatment include reducing the rate of progression of a particular disease, disorder, or condition, ameliorating or alleviating the pathological condition, and achieving remission or improving the prognosis. For example, an individual is successfully "treated" if one or more symptoms associated with a particular disease, disorder, or condition are reduced or eliminated.

[0053] An "effective amount" refers to at least an amount effective, at a dosage and for a period of time necessary, to achieve the desired therapeutic or prophylactic effect. An effective amount can be provided by one or more administrations. As used herein, an effective amount can vary depending on factors such as the individual's condition, age, sex, and weight, as well as the ability of the treatment to elicit a desired response in the individual. An effective amount is also one in which the beneficial effects of the treatment outweigh any toxic or adverse effects. For prophylactic use, beneficial or desired results include results such as elimination or reduction of the risk, reduction in severity, or delay in onset of the disease, including the biochemical, histological, and / or behavioral symptoms of the disease, its complications, and intermediate pathological phenotypes observed during the development of the disease. For therapeutic use, beneficial or desired results include clinical results, such as reduction in one or more symptoms caused by the disease, improvement in the quality of life of an individual suffering from the disease, reduction in the dosage of other drugs required to treat the disease, enhancement of the effect of another drug, for example, via targeting, delay in the progression of the disease, and / or prolongation of survival. An effective amount of a drug, compound, or pharmaceutical composition is an amount sufficient to directly or indirectly achieve preventive or therapeutic treatment.As understood in a clinical context, an effective amount of a drug, compound, or pharmaceutical composition may or may not be achieved in conjunction with another drug, compound, or pharmaceutical composition.Therefore, an "effective amount" may be considered in light of the administration of one or more therapeutic agents, and a single agent may be considered to be given in an effective amount if the desired result can be achieved or is achieved in conjunction with one or more other agents.

[0054] As used herein, administration "in conjunction with" another compound or composition includes simultaneous administration and / or administration at different times. Administration in conjunction also encompasses administration as a simultaneous formulation or as separate compositions, including different dosage times or intervals, and using the same or different routes of administration.

[0055] An "individual" for purposes of treatment, prevention, or risk reduction refers to any animal classified as a mammal, including humans, domestic and farm animals, as well as zoo, sport, or pet animals, such as dogs, horses, rabbits, cows, pigs, hamsters, gerbils, mice, ferrets, rats, cats, etc. Preferably, the individual is a human.

[0056] The term "immunoglobulin" (Ig) is used interchangeably herein with "antibody." The term "antibody" is used herein in the broadest sense to specifically include monoclonal antibodies, polyclonal antibodies, multispecific antibodies (e.g., bispecific antibodies) formed from at least two intact antibodies, and antibody fragments that exhibit only the desired biological activity.

[0057] The basic four-chain antibody unit is a heterotetrameric glycoprotein consisting of two identical light (L) chains and two identical heavy (H) chains. H and V L are paired together to form a single antigen-binding site. For the structure and properties of different classes of antibodies, see, e.g., Basic and Clinical Immunology, 8th Ed., Daniel P. Stites, Abba I. Terr and Tristram G. Parslow (eds.), Appleton & Lange, Norwalk, CT, 1994, page 71 and Chapter 6.

[0058] Light chains from any vertebrate species can be assigned to one of two clearly distinct types, called kappa ("κ") and lambda ("λ"), based on the amino acid sequence of their constant domains. Depending on the amino acid sequence of their heavy chain constant domains (CH), immunoglobulins can be assigned to different classes or isotypes. There are five classes of immunoglobulins: IgA, IgD, IgE, IgG, and IgM, which have heavy chains designated alpha ("α"), delta ("δ"), epsilon ("ε"), gamma ("γ"), and mu ("μ"), respectively. The gamma and alpha classes are further divided into subclasses (isotypes) based on relatively minor differences in the CH sequence and function. For example, humans express the following subclasses: IgG1, IgG2, IgG3, IgG4, IgA1, and IgA2. The subunit structures and three-dimensional configurations of different classes of immunoglobulins are well known; see, e.g., Abbas et al., Cellular and Molecular Immunology, 4 th It is generally described in Saunders Co., ed. (WBSaunders Co., 2000).

[0059] "Native antibodies" are usually heterotetrameric glycoproteins of about 150,000 daltons, composed of two identical light (L) chains and two identical heavy (H) chains. Each light chain is linked to a heavy chain by one covalent disulfide bond, while the number of disulfide linkages varies among the heavy chains of different immunoglobulin isotypes. Each heavy and light chain also has regularly spaced intrachain disulfide bridges. Each heavy chain contains at one end a variable domain (V H ) followed by multiple constant domains. Each light chain has a variable domain (V L ) and a constant domain at its other end, with the light-chain constant domain aligned with the first constant domain of the heavy chain and the light-chain variable domain aligned with the variable domain of the heavy chain. Particular amino acid residues are believed to form an interface between the light- and heavy-chain variable domains.

[0060] An "isolated" antibody, e.g., an anti-CD33 antibody of the present disclosure, is one that has been identified, separated, and / or recovered from components of its production environment (e.g., natural or recombinant). Preferably, an isolated polypeptide is free from all other contaminant components from its production environment. Contaminant components from its production environment, e.g., those resulting from recombinantly transfected cells, are substances that would normally interfere with the antibody's research, diagnostic, or therapeutic use and may include enzymes, hormones, and other proteinaceous or non-proteinaceous solutes. In preferred embodiments, the polypeptide is purified (1) to greater than 95% by weight, and in some embodiments, greater than 99% by weight, of the antibody, e.g., as determined by the Lowry assay; (2) to a degree sufficient to obtain at least 15 residues of N-terminal or internal amino acid sequence by use of a spinning cup sequenator; or (3) to homogeneity by SDS-PAGE under non-reducing or reducing conditions using Coomassie blue or, preferably, silver staining. Isolated antibody includes the antibody in situ within recombinant T cells since at least one component of the antibody's natural environment will not be present. Ordinarily, however, isolated polypeptide or antibody will be prepared by at least one purification step.

[0061] The "variable region" or "variable domain" of an antibody, such as an anti-CD33 antibody of the present disclosure, refers to the amino-terminal domains of the heavy or light chain of the antibody. The variable domains of the heavy and light chains are respectively referred to as "V H " and "V L These domains are usually the most variable parts of the antibody (compared to other antibodies of the same class) and contain the antigen-binding sites.

[0062] The term "variable" refers to the fact that certain segments of the variable domains differ extensively in sequence among antibodies, such as the anti-CD33 antibodies of the present disclosure. The V domains mediate antigen binding and determine the specificity of a particular antibody for its particular antigen. However, the variability is not uniformly distributed throughout the variable domains. Rather, it is concentrated in three segments called hypervariable regions (HVRs) in both the light and heavy chain variable domains. The more highly conserved portions of variable domains are called framework regions (FRs). Naturally occurring heavy and light chain variable domains each contain four FR regions, primarily in a beta-sheet conformation, connected by three HVRs, which form loops that connect, and in some cases form part of, the beta-sheet structure. The HVRs of each chain are closely spaced by the FR regions and linked to the HVRs from other chains, contributing to the formation of the antigen-binding site of antibodies (see Kabat et al., Sequences of Immunological Interest, Fifth Edition, National Institutes of Health, Bethesda, MD (1991)). The constant domains are not directly involved in binding the antibody to an antigen, but exhibit various effector functions, such as involvement in antibody-dependent cellular cytotoxicity of the antibody.

[0063] As used herein, the term "monoclonal antibody" refers to an antibody, such as an anti-CD33 antibody of the present disclosure, obtained from a population of substantially homogeneous antibodies; in other words, the individual antibodies comprising the population are identical except for possible naturally occurring mutations and / or post-translational modifications (e.g., isomerization, amidation), which may be present in minor amounts. Monoclonal antibodies are highly specific and are directed against one or more antigenic sites. In some embodiments, the monoclonal antibodies of the present disclosure may be bispecific. In contrast to polyclonal antibody preparations, which typically include different antibodies directed against different determinants (epitopes), each monoclonal antibody is directed against a single determinant on one or more antigenic sites. The modifier "monoclonal" indicates the character of the antibody as being obtained from a population of substantially homogeneous antibodies and is not to be construed as requiring production of the antibody by any particular method. For example, the monoclonal antibodies used in accordance with the present disclosure can be displayed using, for example, phage display technology (e.g., Clackson et al., Nature, 352:624-628 (1991); Marks et al., J. Mol. Biol. 222:581-597 (1992); Sidhu et al., J. Mol. Biol. 338(2): 299-310 (2004); Lee et al., J. Mol. Biol. 340(5):1073-1093 (2004); Fellouse, Proc. Nat'l Acad. Sci. USA 101(34):12467-472 (2004); and Lee et al., J. Immunol. Methods 284(1-2):119-132(2004), hybridoma method (e.g., Kohler and Milstein, Nature, 256:495-97(1975), Hongo et al., Hybridoma, 14(3):253-260(1995), Harlow et al., Antibodies: A Laboratory Manual, (Cold Spring Harbor Laboratory Press, 2nd ed. 1988), Hammerling et al., in: Monoclonal Antibodies and T-Cell Hybridomas 563-681 (Elsevier, NY, 1981)), recombinant DNA methods (see, e.g., U.S. Pat. No. 4,816,567), yeast display technology (see, e.g., WO2009 / 036379A2, WO2010105256, WO2012009568, and Xu et al., Protein Eng. Des. Sel., 26(10):663-70 (2013)), and techniques for producing human or human-like antibodies in animals that have some or all of the human immunoglobulin loci or genes encoding human immunoglobulin sequences (see, e.g., WO 1998 / 24893, WO 1996 / 34096, WO 1996 / 33735, WO 1991 / 10741, Jakobovits et al. al., Proc. Nat'l Acad. Sci. USA 90:2551(1993), Jakobovits et al., Nature 362:255-258(1993), Bruggemann et al., Year in Immunol.7:33 (1993), U.S. Patent Nos. 5,545,807, 5,545,806, 5,569,825, 5,625,126, 5,633,425, and 5,661,016, Marks et al.,Bio / Technology 10:779-783(1992), Lonberg et al., Nature 368:856-859(1994), Morrison, Nature 368:812-813 (1994); Fishwild et al., Nature Biotechnol. 14:845-851 (1996); Neuberger, Nature Biotechnol. 14:826 (1996); and Lonberg and Huszar, Intern. Rev. Immunol. 13:65-93 (1995)).

[0064] The terms "full-length antibody," "intact antibody," or "whole antibody" are used interchangeably and refer to an antibody in its substantially intact form, e.g., an anti-CD33 antibody of the present disclosure, as opposed to an antibody fragment. Specifically, a whole antibody includes heavy and light chains comprising an Fc region. The constant domains may be native-sequence constant domains (e.g., human native-sequence constant domains) or amino acid sequence variants thereof. In some cases, the intact antibody may have one or more effector functions.

[0065] An "antibody fragment" comprises a portion of an intact antibody, preferably the antigen-binding and / or variable region of the intact antibody. Examples of antibody fragments include Fab, Fab', F(ab'), and Fv fragments, diabodies, linear antibodies (see U.S. Pat. No. 5,641,870, Example 2; Zapata et al., Protein Eng. 8(10):1057-1062 (1995)), single-chain antibody molecules, and multispecific antibodies formed from antibody fragments.

[0066] Papain digestion of antibodies, such as the anti-CD33 antibodies of the present disclosure, produces two identical antigen-binding fragments called "Fab" fragments, and a residual "Fc" fragment, a designation reflecting the ability to readily crystallize. The Fab fragment contains the entire light chain along with the variable region domain of the heavy chain (V H ) and the first constant domain of one heavy chain (C H 1). Each Fab fragment is monovalent with respect to antigen binding; in other words, it has a single antigen-binding site. Pepsin treatment of an antibody yields a single large F(ab')2 fragment that roughly corresponds to the two disulfide-linked Fab fragments with different antigen-binding activities and that are still capable of cross-linking antigen. The Fab' fragment is C HF(ab')2 antibody fragments differ from Fab fragments by having several additional residues at the carboxy terminus of one domain, including one or more cysteines from the antibody hinge region. Fab'-SH is the designation used herein for Fab', in which the cysteine ​​residue(s) in the constant domains bear a free thiol group. F(ab')2 antibody fragments were originally produced as pairs of Fab' fragments with hinge cysteines between them. Other chemical linkages of antibody fragments are also known.

[0067] The Fc fragment contains the carboxy-terminal portions of both H chains linked by disulfides. The effector functions of the antibody are determined by the sequences in the Fc region, which are also recognized by Fc receptors (FcRs) found on certain types of cells.

[0068] An "Fv" is the minimum antibody fragment that contains a complete antigen-recognition and binding site. This fragment consists of a dimer of one heavy-chain and one light-chain variable region domain in tight, non-covalent association. Folding of these two domains generates six hypervariable loops (three loops each from the H and L chain), which provide the amino acid residues for antigen binding and confer antigen-binding specificity to the antibody. However, even a single variable domain (or half of an Fv containing only the three antigen-specific HVRs) has the ability to recognize and bind antigen, albeit with lower affinity than the entire binding site.

[0069] "Single-chain Fv," also abbreviated as "sFv" or "scFv," is an antibody fragment comprising the VH and VL antibody domains connected in a single polypeptide chain. Preferably, the sFv polypeptide further comprises a VH domain that enables the sFv to form the desired structure for antigen binding. H and V L For a review of sFvs, see Pluckthun in The Pharmacology of Monoclonal Antibodies, vol. 113, Rosenburg and Moore eds., Springer-Verlag, New York, pp. 269-315 (1994).

[0070] A "functional fragment" of an antibody, e.g., an anti-CD33 antibody of the present disclosure, typically comprises a portion of the intact antibody, including the antigen-binding or variable region of the intact antibody, or the F region of the antibody that retains FcR binding ability or has modified FcR binding ability. Examples of antibody fragments include linear antibodies, single-chain antibody molecules, and multispecific antibodies formed from antibody fragments.

[0071] The term "diabody" refers to a V H and V L This refers to small antibody fragments prepared by constructing sFv fragments (see previous paragraph) such that interchain, rather than intrachain, pairing of the V domains is achieved by a short linker (about 5-10 residues) between the domains, thereby producing a bivalent fragment, i.e., a fragment with two antigen-binding sites. Bispecific diabodies are heterodimers of two "crossover" sFv fragments, where the V domains of the two antibodies H and V L The domains are present on different polypeptide chains. Diabodies are described in detail, for example, in EP 404,097, WO 93 / 11161, and Hollinger et al., Proc. Nat'l Acad. Sci. USA 90:6444-48 (1993).

[0072] As used herein, "chimeric antibody" refers to antibodies (immunoglobulins), such as the anti-CD33 antibodies of the present disclosure, in which a portion of the heavy and / or light chain is identical to or homologous to corresponding sequences in antibodies derived from a particular species or belonging to a particular antibody class or subclass, while the remainder of the chain(s) is identical to or homologous to corresponding sequences in antibodies derived from another species or belonging to another antibody class or subclass, as well as fragments of such antibodies, so long as they exhibit the desired biological activity (U.S. Pat. No. 4,816,567; Morrison et al., Proc. Nat'l Acad. Sci. USA, 81:6851-55 (1984)). Chimeric antibodies of interest herein include PRIMATIZED® antibodies, whose antigen-binding regions are derived from, for example, antibodies produced by immunizing macaques with the antigen of interest. As used herein, "humanized antibodies" refers to a subset of "chimeric antibodies."

[0073] "Humanized" forms of non-human (e.g., murine) antibodies, such as the anti-CD33 antibodies of the present disclosure, are chimeric antibodies that contain minimal sequence derived from non-human immunoglobulins. In one embodiment, a humanized antibody is a human immunoglobulin (recipient antibody) in which residues from an HVR of the recipient are replaced by residues from an HVR of a non-human species (donor antibody), e.g., mouse, rat, rabbit, or non-human primate, possessing the desired specificity, affinity, and / or capacity. In some instances, FR residues of the human immunoglobulin are replaced by corresponding non-human residues. Furthermore, humanized antibodies may comprise residues that are not found in either the recipient antibody or the donor antibody. These modifications may be made to further improve antibody performance, such as binding affinity. Generally, a humanized antibody will comprise substantially all of at least one, and usually two, variable domains, in which all or substantially all of the hypervariable loops correspond to those of a non-human immunoglobulin sequence, and all or substantially all of the FR regions are those of a human immunoglobulin sequence, but the FR regions may comprise substitutions of one or more individual FR residues which improve antibody performance, such as binding affinity, isomerization, immunogenicity, etc. The number of these FR amino acid substitutions will usually not exceed six in the H chain and three in the L chain. The humanized antibody also optionally will comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. For further details, see, e.g., Jones et al., Nature 321:522-525 (1986), Riechmann et al., Nature 332:323-329 (1988), and Presta, Curr. Op. Struct. Biol. 2:593-596 (1992). See also, e.g., Vaswani and Hamilton, Ann. Allergy, Asthma & Immunol. 1:105-115 (1998), Harris, Biochem. Soc. Transactions 23:1035-1038 (1995), Hurle and Gross, Curr. Op. Biotech. 5:428-433 (1994), and U.S. Patent Nos. 6,982,321 and 7,087,409.

[0074] A "human antibody" is one that has an amino acid sequence corresponding to that of an antibody, such as the anti-CD33 antibody of the present disclosure, produced by a human and / or produced using any of the techniques for producing human antibodies disclosed herein. This definition of a human antibody specifically excludes humanized antibodies that contain non-human antigen-binding residues. Human antibodies can be produced using a variety of techniques known in the art, including phage display libraries. See Hoogenboom and Winter, J. Mol. Biol., 227:381 (1991); Marks et al., J. Mol. Biol., 222:581 (1991). Similarly applicable to the preparation of human monoclonal antibodies are the methods described in Cole et al., Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, p. 77 (1985); and Boerner et al., J. Immunol., 147(1):86-95 (1991). See also van Dijk and van de Winkel, Curr. Opin. Pharmacol. 5:368-74 (2001). Human antibodies can be prepared by administering antigen to transgenic animals, e.g., immunized xenomouse (see, e.g., U.S. Patent Nos. 6,075,181 and 6,150,584 regarding XENOMOUSE™ technology), which have been engineered to produce such antibodies in response to antigen challenge, but whose endogenous gene loci have been disabled. See also, e.g., Li et al., Proc. Nat'l Acad. Sci. USA, 103:3557-3562 (2006), regarding human antibodies generated by human B cell hybridoma technology. Alternatively, human antibodies can be prepared using yeast libraries and methods disclosed in, for example, WO2009 / 036379A2, WO2010105256, WO2012009568, and Xu et al., Protein Eng. Des. Sel., 26(10):663-70 (2013).

[0075] As used herein, the terms "hypervariable region," "HVR," or "HV" refer to the region of an antibody variable domain, such as that of an anti-CD33 antibody of the present disclosure, that is hypervariable in sequence and / or forms structurally distinct loops. Antibodies generally contain six HVRs: three in the VH (H1, H2, and H3) and three in the VL (L1, L2, and L3). In natural antibodies, H3 and L3 exhibit the greatest diversity among the six HVRs, and H3 in particular is thought to play a unique role in conferring fine specificity to antibodies. See, e.g., Xu et al., Immunity 13:37-45 (2000); Johnson and Wu in Methods in Molecular Biology 248:1-25 (Lo, ed., Human Press, Totowa, NJ, 2003). In fact, naturally occurring camelid antibodies consisting only of heavy chains are functional and stable in the absence of light chains. See, e.g., Hamers-Casterman et al., Nature 363:446-448 (1993) and Sheriff et al., Nature Struct. Biol. 3:733-736 (1996).

[0076] Several HVR delineations are in use and are encompassed herein. In some embodiments, the HVR may be a Kabat complementarity-determining region (CDR), which is based on sequence diversity and is the most commonly used (Kabat et al., supra). In some embodiments, the HVR may be a Chothia CDR. Chothia instead refers to the location of a structural loop (Chothia and Lesk J. Mol. Biol. 196:901-917 (1987)). In some embodiments, the HVR may be an AbM HVR. AbM HVRs represent the intermediate between a Kabat CDR and a Chothia structural loop and are used by Oxford Molecular's AbM antibody modeling software. In some embodiments, the HVR may be a "contact" HVR. "Contact" HVRs are based on analysis of available complex crystal structures. Residues from each of these HVRs are listed below. TIFF2025176024000002.tif50170

[0077] HVRs may include the following "extended HVRs": 24-36 or 24-34 (L1), 46-56 or 50-56 (L2), and 89-97 or 89-96 (L3) in VL, and 26-35 (H1), 50-65 or 49-65 (preferred embodiment) (H2), and 93-102, 94-102, or 95-102 (H3) in VH. The variable domain residues are numbered for each of these extended HVR definitions according to EU or Kabat et al., supra.

[0078] "Framework" or "FR" residues are those variable domain residues other than the HVR residues as herein defined.

[0079] The phrases "variable domain residue numbering according to EU or Kabat" or "amino acid position numbering according to EU or Kabat" and variations thereof refer to the numbering system used for the heavy or light chain variable domains of the antibody compilation in EU or Kabat et al., supra. Using this numbering system, the actual linear amino acid sequence may contain fewer or additional amino acids corresponding to a shortening of, or insertion into, a FR or HVR of the variable domain. For example, a heavy chain variable domain may contain a single amino acid insertion after residue 52 of H2 (residue 52a according to Kabat) and inserted residues after heavy chain FR residue 82 (e.g., residues 82a, 82b, and 82c, etc., according to Kabat). The EU or Kabat numbering of residues can be determined for a given antibody by alignment of the "standard" Kabat numbering sequence with the homologous regions of that antibody's sequence.

[0080] The EU or Kabat numbering system is typically used when referring to residues in the variable domain (approximately residues 1-107 of the light chain and residues 1-113 of the heavy chain) (e.g., Kabat et al., Sequences of Immunological Interest. 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991)). The "EU or Kabat numbering system" or "EU index" is typically used when referring to residues in the immunoglobulin heavy chain constant region (e.g., the EU index reported in Kabat et al., supra). The "EU index according to Kabat" refers to the numbering of residues in a human IgG1 EU antibody. Unless otherwise specified herein, references to residue numbers in the variable domain of an antibody refer to residue numbers according to the Kabat numbering system. Unless otherwise specified herein, references to residue numbers in the constant domain of an antibody refer to residue numbers according to the EU or Kabat numbering system (see, e.g., U.S. Patent Publication No. 2010-280227).

[0081] As used herein, an "acceptor human framework" is a framework that comprises the amino acid sequence of a VL or VH framework derived from a human immunoglobulin framework or a human consensus framework. An acceptor human framework "derived from" a human immunoglobulin framework or a human consensus framework may comprise the same amino acid sequence or may contain pre-existing amino acid sequence changes. In some embodiments, the number of pre-existing amino acid changes is 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, or 2 or less. When pre-existing amino acid changes are present in the VH, preferably, those changes occur at only three, two, or one of positions 71H, 73H, and 78H; for example, the amino acid residues at those positions may be 71A, 73T, and / or 78A. In one embodiment, the VL acceptor human framework is identical in sequence to the VL human immunoglobulin framework sequence or human consensus framework sequence.

[0082] A "human consensus framework" is a framework that represents the most commonly occurring amino acid residues in a selection of human immunoglobulin VL or VH framework sequences. Generally, the selection of the human immunoglobulin VL or VH sequence is from a subgroup of variable domain sequences. Generally, the subgroup of sequences is a subgroup according to Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, MD (1991). Examples include, for the VL, the subgroup can be subgroup kappa I, kappa II, kappa III, or kappa IV according to Kabat et al., supra. Additionally, for the VH, the subgroup can be subgroup I, subgroup II, or subgroup III according to Kabat et al., supra.

[0083] For example, an "amino acid modification" at a specific position in an anti-CD33 antibody of the present disclosure refers to the substitution or deletion of the specific residue, or the insertion of at least one amino acid residue adjacent to the specific residue. An insertion "adjacent" a specific residue means an insertion within 1 to 2 residues of the specific residue. The insertion may be on the N-terminal or C-terminal side of the specific residue. A preferred amino acid modification herein is a substitution.

[0084] An "affinity matured" antibody, such as an anti-CD33 antibody of the present disclosure, is one that contains one or more alterations in one or more HVRs thereof that result in an improvement in the affinity of the antibody for antigen compared to a parent antibody lacking those alteration(s). In one embodiment, the affinity matured antibody has nanomolar or even picomolar affinity for the target antigen. Affinity matured antibodies are produced by procedures known in the art. For example, Marks et al., Bio / Technology 10:779-783 (1992) describe affinity maturation by shuffling VH and VL domains. Random mutagenesis of HVR and / or framework residues has been described, for example, by Barbas et al. Proc Nat. Acad. Sci. USA 91:3809-3813 (1994), Schier et al. Gene 169:147-155 (1995), Yelton et al. J. Immunol. 155:1994-2004 (1995), Jackson et al., J. Immunol. 154(7):3310-9 (1995), and Hawkins et al., J. Mol. Biol. 226:889-896 (1992).

[0085] As used herein, the terms "specifically recognize" or "specifically bind" refer to a measurable and reproducible interaction, such as attraction or binding, between a target and an antibody, e.g., an anti-CD33 antibody of the present disclosure, i.e., a determinant of the presence of the target in the presence of a heterogeneous population of molecules, including biomolecules. For example, an antibody that specifically or preferentially binds to a target or epitope, e.g., an anti-CD33 antibody of the present disclosure, is an antibody that binds to this target or epitope with greater affinity, avidity, more readily, and / or for a longer period of time than it binds to other targets or other epitopes of that target. Reading this definition, it is understood that, for example, an antibody (or moiety) that specifically or preferentially binds to a first target may or may not specifically or preferentially bind to a second target. Thus, "specific binding" or "preferential binding" does not necessarily require (although it can include) exclusive binding. An antibody that specifically binds to a target has at least about 10 3 M -1 Or 10 4 M -1 , sometimes about 10 5 M -1 Or 10 6 M -1 , and in other cases, about 10 6 M -1 Or 10 7 M -1 , about 10 8 M -1 ~10 9 M -1 , or about 10 10 M -1 ~10 11 M -1or higher. A variety of immunoassay formats can be used to select antibodies specifically immunoreactive with a particular protein. For example, solid-phase ELISA immunoassays are commonly used to select monoclonal antibodies specifically immunoreactive with a protein. See, for example, Harlow and Lane (1988) Antibodies, A Laboratory Manual, Cold Spring Harbor Publications, New York, for a description of immunoassay formats and conditions that can be used to measure specific immunoreactivity.

[0086] As used herein, an "interaction" between a CD33 protein and a second protein includes, without limitation, protein-protein interactions, physical interactions, chemical interactions, bonds, covalent bonds, and ionic bonds. As used herein, an antibody "inhibits the interaction" between two proteins if the antibody disrupts, reduces, or completely eliminates the interaction between the two proteins. An antibody or fragment thereof of the present disclosure "inhibits the interaction" between two proteins if the antibody or fragment thereof binds to one of the two proteins.

[0087] An "agonist" or "activating" antibody is an antibody, such as an agonist anti-CD33 antibody of the present disclosure, that induces (e.g., increases) one or more activities or functions of an antigen after the antibody binds to the antigen.

[0088] A "blocking," "antagonist," or "inhibitory" antibody is an antibody, such as an anti-CD33 antibody of the present disclosure, that inhibits or reduces (e.g., decreases) antigen binding to one or more ligands after the antibody binds to the antigen and / or inhibits or reduces (e.g., decreases) one or more activities or functions of the antigen after the antibody binds to the antigen. In some embodiments, a blocking, antagonist, or inhibitory antibody substantially or completely inhibits antigen binding to one or more ligands and / or one or more activities or functions of the antigen.

[0089] Antibody "effector functions" refer to the biological activities attributable to the Fc region of an antibody (a native sequence Fc region or amino acid sequence variant Fc region), and vary depending on the antibody isotype.

[0090] As used herein, the term "Fc region" is used to define the C-terminal region of an immunoglobulin heavy chain, including native-sequence Fc regions and variant Fc regions. Although the boundaries of the Fc region of an immunoglobulin heavy chain can vary, the human IgG heavy chain Fc region is usually defined to stretch from the amino acid residue at position Cys226, or from Pro230, to the carboxyl terminus. The C-terminal lysine of the Fc region (residue 447 according to the EU or Kabat numbering system) may be removed, for example, during antibody production or purification, or by recombinantly engineering the nucleic acid encoding the antibody heavy chain. Thus, a composition of intact antibodies may include antibody populations in which all K447 residues have been removed, antibody populations in which the K447 residue has not been removed, and antibody populations having a mixture of antibodies with and without the K447 residue. Suitable native-sequence Fc regions for the antibodies of the present disclosure include human IgG1, IgG2, IgG3, and IgG4.

[0091] A "native sequence Fc region" comprises an amino acid sequence identical to that of an Fc region found in nature. Native sequence human 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, as well as naturally occurring variants thereof.

[0092] A "variant Fc region" comprises an amino acid sequence that differs from that of a native-sequence Fc region by at least one amino acid modification, preferably one or more amino acid substitutions. Preferably, the variant Fc region has at least one amino acid substitution, for example, about one to about ten amino acid substitutions, preferably about one to about five amino acid substitutions, relative to the native-sequence Fc region or the Fc region of a parent polypeptide. As used herein, the variant Fc region preferably has at least about 80% homology to the native-sequence Fc region and / or the Fc region of the parent polypeptide, most preferably at least about 90% homology, and more preferably at least about 95% homology.

[0093] "Fc receptor" or "FcR" refers to a receptor that binds to the Fc region of an antibody. A preferred FcR is a native-sequence human FcR. Furthermore, a preferred FcR is one that binds IgG antibodies (gamma receptors), including receptors of the FcγRI, FcγRII, and FcγRIII subclasses, as well as allelic variants and alternatively spliced ​​forms of these receptors. FcγRII receptors include FcγRIIA (an "activating receptor") and FcγRIIB (an "inhibiting receptor"), which have similar amino acid sequences that differ primarily in their cytoplasmic domains. Activating receptor FcγRIIA contains an immunoreceptor tyrosine-based activation motif ("ITAM") in its cytoplasmic domain. Inhibiting receptor FcγRIIB contains an immunoreceptor tyrosine-based inhibition motif ("ITIM") in its cytoplasmic domain (see, e.g., M. Daeron, Annu. Rev. Immunol. 15:203-234 (1997)). FcRs are reviewed in Ravetch and Kinet, Annu. Rev. Immunol. 9:457-92 (1991), Capel et al., Immunomethods 4:25-34 (1994), and de Haas et al., J. Lab. Clin. Med. 126:330-41 (1995). Other FcRs, including those yet to be identified, are encompassed by the term "FcR" herein. FcRs may also extend the serum half-life of antibodies.

[0094] In vivo binding to FcRn and serum half-life of human FcRn high-affinity binding polypeptides can be assayed, for example, in transgenic mice or transfected human cell lines expressing human FcRn, or in primates to which polypeptides having variant Fc regions are administered. WO 2004 / 42072 (Presta) describes antibody variants with improved or diminished binding to FcRs. See also, e.g., Shields et al., J. Biol. Chem. 9(2):6591-6604 (2001).

[0095] As used herein with respect to peptide, polypeptide, or antibody sequences, "percent (%) amino acid sequence identity" and "homology" refer to the percentage of amino acid residues in a candidate sequence that are identical to those in a particular peptide or polypeptide sequence after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity, without considering conservative substitutions as part of the sequence identity. Alignment for purposes of determining percent amino acid sequence identity can be accomplished in a variety of ways within the skill of those in the art, for example, using publicly available computer software such as BLAST, BLAST-2, ALIGN, or MEGALIGN™ (DNASTAR) software. Those skilled in the art can determine appropriate parameters for alignment comparisons, including any algorithms known in the art necessary to achieve maximal alignment over the full length of the sequences being compared.

[0096] An "isolated" nucleic acid molecule encoding an antibody, e.g., an anti-CD33 antibody of the present disclosure, is a nucleic acid molecule that has been identified and separated from at least one contaminant nucleic acid molecule with which it is normally associated in the environment in which it is produced. Preferably, the isolated nucleic acid is free from association with all components with which it is associated in the environment in which it is produced. Isolated nucleic acid molecules encoding the polypeptides and antibodies herein are in a form other than in the form or setting in which they are found in nature. Isolated nucleic acid molecules are therefore distinguished from nucleic acids encoding the polypeptides and antibodies herein that are naturally present in a cell.

[0097] As used herein, the term "vector" is intended to refer to a nucleic acid molecule capable of transporting another nucleic acid to which it has been linked. One type of vector is a "plasmid," which refers to a circular double-stranded DNA into which additional DNA segments can be ligated. Another type of vector is a phage vector. Another type of vector is a viral vector, in which additional DNA segments can be ligated into the viral genome. Certain vectors are capable of autonomous replication in a host cell into which they are introduced (e.g., bacterial vectors having a bacterial origin of replication and episomal mammalian vectors). Other vectors (e.g., non-episomal mammalian vectors) can be integrated into the genome of a host cell upon introduction into the host cell, and thereby are replicated along with the host genome. Moreover, certain vectors are capable of directing the expression of genes to which they are operably linked. Such vectors are referred to herein as "recombinant expression vectors," or simply "expression vectors." In general, expression vectors useful in recombinant DNA techniques are often in the form of plasmids. As the plasmid is the most commonly used form of vector, "plasmid" and "vector" may be used interchangeably herein.

[0098] As used interchangeably herein, "polynucleotide" or "nucleic acid" refers to a polymer of nucleotides of any length, including DNA and RNA. The nucleotides can be deoxyribonucleotides, ribonucleotides, modified nucleotides or bases, and / or their analogs, or any substrate that can be introduced into a polymer by DNA or RNA polymerase or by a synthetic reaction. A polynucleotide can contain modified nucleotides, such as methylated nucleotides and their analogs. Modifications to the nucleotide structure, if present, can be imparted before or after assembly of the polymer. The sequence of nucleotides can be interrupted by non-nucleotide components. A polynucleotide can also contain modification(s) made after synthesis, such as, for example, conjugation to a label. Other types of modifications include, for example, "caps," substitution of one or more naturally occurring nucleotides with an analog, internucleotide modifications such as those with uncharged linkages (e.g., methylphosphonates, phosphotriesters, phosphoamidates, carbamates, etc.) and charged linkages (e.g., phosphorothioates, phosphorodithioates, etc.), those containing pendant moieties such as proteins (e.g., nucleases, toxins, antibodies, signal peptides, ply-L-lysine, etc.), intercalating agents (e.g., acridine, psoralens, etc.), those containing chelators (e.g., metals, radioactive metals, boron, metal oxides, etc.), those containing alkylating agents, those with modified linkages (e.g., alpha anomeric nucleic acids, etc.), and unmodified forms of the polynucleotide(s). Additionally, any of the hydroxyl groups normally present on the sugar may be substituted with, for example, a phosphonate group, a phosphate group, protected with a standard protecting group, or activated to make additional bonds to additional nucleotides, or attached to a solid or semi-solid support. The 5' and 3' terminal OH may be phosphorylated, amine-substituted, or substituted with an organic capping group moiety of 1 to 20 carbon atoms. Other hydroxyls may also be derivatized to standard protecting groups.Polynucleotides can also include analogous forms of ribose or deoxyribose sugars commonly known in the art, such as 2'-O-methylribose, 2'-O-allylribose, 2'-fluororibose, or 2'-azidoribose, carbocyclic sugar analogs, α-anomeric sugars, epimeric sugars such as arabinose, xylose, or lyxose, pyranose sugars, furanose sugars, sedoheptulose, acyclic analogs, and basic nucleoside analogs, such as methyl riboside. One or more phosphodiester linkages can be replaced by alternative linking groups. These alternative linking groups include, but are not limited to, embodiments in which the phosphate is replaced by P(O)S (thioate), P(S)S (dithioate), (O)NR2 (amidate), P(O)R, P(O)OR', CO, or CH2 (formacetal), where each R or R' is independently H or a substituted or unsubstituted alkyl (1-20C), aryl, alkenyl, cycloalkyl, cycloalkenyl, or araldyl, optionally containing an ether (-O-) linkage. Not all linkages in a polynucleotide need be identical. The foregoing description applies to all polynucleotides referred to herein, including RNA and DNA.

[0099] A "host cell" includes an individual cell or cell culture that can be or has been a recipient for a vector(s) for the introduction of a polynucleotide insert. A host cell includes the progeny of a single host cell, which may not necessarily be completely identical (in morphology or genomic DNA complement) to the original parent cell due to natural, accidental, or deliberate mutation. A host cell includes cells transfected in vivo with a polynucleotide(s) of the present disclosure.

[0100] As used herein, "carrier" includes pharmaceutically acceptable carriers, excipients, or stabilizers that are not toxic to cells or mammals exposed thereto at the dosages and concentrations used. Often, physiologically acceptable carriers are pH-buffered aqueous solutions. Examples of physiologically acceptable carriers include buffers such as phosphate, citrate, and other organic acids; antioxidants, including ascorbic acid; low molecular weight (less than about 10 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™, polyethylene glycol (PEG), and PLURONICS™.

[0101] As used herein, the term "about" refers to a normal range of error for the respective value, readily known to one of ordinary skill in the art. As used herein, reference to "about" a value or parameter includes (and indicates) embodiments that are directed to that value or parameter itself.

[0102] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. For example, reference to an "antibody" is a reference to one to many antibodies, e.g., molar amounts, and includes equivalents thereof known to those skilled in the art, and so forth.

[0103] Aspects and embodiments of the present disclosure described herein are understood to include "comprising," "consisting of," and "consisting essentially of" aspects and embodiments.

[0104] overview The present disclosure relates, in part, to anti-CD33 antibodies with improved and / or enhanced functional properties (e.g., relative to an anti-CD33 antibody having a heavy chain variable region comprising the sequence of SEQ ID NO: 103 and a light chain variable region comprising the sequence of SEQ ID NO: 104), including, for example, antibodies capable of reducing cell surface CD33 levels and / or binding to CD33 with improved / enhanced kinetics, methods of making and using such antibodies, pharmaceutical compositions comprising such antibodies, nucleic acids encoding such antibodies, and host cells comprising nucleic acids encoding such antibodies.

[0105] In some embodiments, the anti-CD33 antibodies of the present disclosure have one or more activities attributable, at least in part, to the ability of the antibody to inhibit the interaction between CD33 and one or more natural glycan ligands. In some embodiments, the anti-CD33 antibodies of the present disclosure may have one or more activities attributable, at least in part, to the ability of the antibody to reduce cellular expression (e.g., cell surface expression) of CD33 by inducing degradation, downregulation, cleavage, receptor desensitization, and / or lysosomal targeting of CD33. In some embodiments, the anti-CD33 antibodies exhibit one or more of the following properties: a. A dissociation constant (K) for human CD33 D ) is lower than that of an anti-CD33 antibody having a heavy chain variable region comprising the sequence of SEQ ID NO: 103 and a light chain variable region comprising the sequence of SEQ ID NO: 104. b. Binds to human cells, such as primary human dendritic cells. c. Reduces cell surface CD33 levels to a lower half effective concentration (EC ) than that of an anti-CD33 antibody having a heavy chain variable region comprising the sequence of SEQ ID NO: 103 and a light chain variable region comprising the sequence of SEQ ID NO: 104. 50 ) (e.g., reducing cell surface CD33 levels in primary human dendritic cells in vitro). D The dissociation constant (K) of α-glucan for human CD33 was measured by surface plasmon resonance or BioLayer interferometry. D ) can be in the range of about 8.57 nM to about 4.1 pM. and / or e.g., EC 50Cell surface CD33 levels, as measured by flow cytometry in vitro, were measured at half effective concentrations (EC ), which may range from about 151.1 pM to about 4.1 pM. 50 ) (e.g., reduce cell surface CD33 levels in primary human dendritic cells in vitro). 50 ) refers to the concentration at which an anti-CD33 antibody of the disclosure reduces the cellular levels of CD33 on or within cells to half of that of untreated cells, or the concentration at which the antibody achieves half-maximal binding to CD33 on cells.

[0106] Advantageously, the anti-CD33 antibodies of the present disclosure exhibit more potent (e.g., lower EC 50 (e.g., by approximately 18-fold) (see Example 2). Additionally, advantageously, the anti-CD33 antibodies of the present disclosure have a higher affinity for CD33 (e.g., up to approximately 25-fold higher affinity) (e.g., K as measured by surface plasmon resonance) compared to a control anti-CD33 antibody (e.g., a control anti-CD33 antibody having a heavy chain variable region comprising the sequence of SEQ ID NO: 103 and a light chain variable region comprising the sequence of SEQ ID NO: 104). D values ​​are low) (see, e.g., Examples 1 and 3). Surprisingly, higher affinity for CD33 does not necessarily correlate with increased potency or potency in reducing cell surface CD33 expression (see, e.g., Examples 2 and 5).

[0107] Certain aspects of the present disclosure are based, at least in part, on the identification of anti-CD33 antibodies with improved and / or enhanced functional properties (e.g., relative to an anti-CD33 antibody having a heavy chain variable region comprising the sequence of SEQ ID NO: 103 and a light chain variable region comprising the sequence of SEQ ID NO: 104), including an improved / enhanced ability to reduce cell surface levels of CD33 on cells, resulting in the reduction, neutralization, prevention, or inhibition of one or more CD33 activities, including, without limitation, reduced proliferation of monocytes, macrophages, T cells, dendritic cells, and / or microglia; reduced T cell proliferation induced by dendritic cells, bone marrow-derived dendritic cells, monocytes, microglia, M1 microglia, activated M1 microglia, M2 microglia, macrophages, M1 macrophages, activated M1 macrophages, and / or M2 macrophages; Reduced survival of M1 macrophages, activated M1 macrophages, M2 macrophages, monocytes, osteoclasts, T cells, T helper cells, cytotoxic T cells, granulocytes, microglia, M1 microglia, activated M1 microglia, and / or M2 microglia, neutrophils, dendritic cells, bone marrow-derived dendritic cells, macrophages, M1 macrophages, activated M1 macrophages, M2 macrophages, monocytes, osteoclasts, T cells, T helper cells, cytotoxic T cells Reduction of proliferation of T cells, granulocytes, microglia, M1 microglia, activated M1 microglia, and / or M2 microglia; Inhibition of migration of neutrophils, dendritic cells, bone marrow-derived dendritic cells, macrophages, M1 macrophages, activated M1 macrophages, M2 macrophages, monocytes, osteoclasts, T cells, T helper cells, cytotoxic T cells, granulocytes, microglia, M1 microglia, activated M1 microglia, and / or M2 microglia; reduction in one or more functions of monocytes, macrophages, dendritic cells, bone marrow derived dendritic cells, macrophages, M1 macrophages, activated M1 macrophages, M2 macrophages, monocytes, osteoclasts, T cells, T helper cells, cytotoxic T cells, granulocytes, microglia, M1 microglia, activated M1 microglia, and / or M2 microglia; reduction in proliferation of monocytes, macrophages, T cells, dendritic cells, neutrophils, and / or microglia;Reduction of the overall function of dendritic cells, neutrophils, and / or microglia; inhibition of beneficial immune responses against different types of cancer selected from bladder cancer, brain cancer, breast cancer, colon cancer, rectal cancer, endometrial cancer, kidney cancer, renal cell carcinoma, renal pelvis cancer, leukemia, lung cancer, melanoma, non-Hodgkin's lymphoma, acute myeloid leukemia, pancreatic cancer, prostate cancer, ovarian cancer, fibrosarcoma, and thyroid cancer; dementia, frontotemporal dementia, Alzheimer's disease, vascular dementia, mixed dementia, Creutzfeldt-Jakob disease, normal pressure hydrocephalus, amyotrophic lateral sclerosis, Huntington's disease, tauopathy, Nasu-Hakola disease, stroke, acute Inhibition of beneficial immune responses to different types of neurological disorders selected from trauma, chronic trauma, essential tremor, Behcet's disease, Parkinson's disease, dementia with Lewy bodies, multiple system atrophy, Shy-Drager syndrome, progressive supranuclear palsy, corticobasal ganglionic degeneration, acute disseminated encephalomyelitis, granulomatous disease, sarcoidosis, age-related diseases, stroke, spinal cord injury, traumatic brain injury, age-related macular degeneration, glaucoma, retinitis pigmentosa, retinal degeneration, and multiple sclerosis; binding to CD33 ligand on tumor cells; dendritic cells, bone marrow-derived dendritic cells, monocytes, microglia, T cells, neutrophils, and inhibition of tumor cell killing by one or more of microglia, macrophages, dendritic cells, bone marrow-derived dendritic cells, neutrophils, T cells, T helper cells, or cytotoxic T cells; inhibition of anti-tumor cell proliferation activity of one or more of microglia, macrophages, dendritic cells, bone marrow-derived dendritic cells, neutrophils, T cells, T helper cells, or cytotoxic T cells; inhibition of tumor cell killing by one or more of microglia, macrophages, dendritic cells, bone marrow-derived dendritic cells, neutrophils, T cells, T helper cells, or cytotoxic T cells inhibiting the anti-tumor cell metastasis activity of one or more of microglia, macrophages, dendritic cells, bone marrow-derived dendritic cells, neutrophils, T cells, T helper cells, or cytotoxic T cells; modulating the expression of one or more inflammatory receptors, e.g., CD86, expressed on one or more of microglia, macrophages, dendritic cells, bone marrow-derived dendritic cells, neutrophils, T cells, T helper cells, or cytotoxic T cells; inhibiting the anti-tumor cell metastasis activity of one or more of microglia, macrophages, dendritic cells, bone marrow-derived dendritic cells, neutrophils, T cells, T helper cells, or cytotoxic T cells; modulating the expression of one or more of immunosuppressive dendritic cells, immunosuppressive macrophages, myeloid-derived suppressor cells, tumor-associated macrophages, immunosuppressive neutrophils, and regulatory T cells;Increased tumor infiltration, increased numbers of tumor-promoting myeloid / granulocytic immunosuppressive cells in tumors, peripheral blood, or other lymphoid organs, enhanced tumor-promoting activity of myeloid-derived suppressor cells, decreased activity of tumor-killing tumor-specific T lymphocytes, decreased infiltration of tumor-killing tumor-specific T lymphocytes, increased tumor growth rate, increased tumor recurrence rate, one or more immunotherapies modulating anti-tumor T cell responses, optionally including one or more of CD40, OX40, ICOS, CD28, CD137 / 4-1BB, CD27, GITR, PD-L1, CTLA4, PD-L2, PD-1, B7- H3, B7-H4, HVEM, LIGHT, BTLA, VISTA, KIR, GAL9, TIM1, TIM3, TIM4, A2AR, LAG3, DR-5, CD39, CD70, TREM1, TREM2, Siglec-5, Siglec-7, Siglec-9, Siglec-11, SirpA, CD447, CSF-1 receptor, and any combination thereof, or a reduction in the effectiveness of one or more immunotherapies, or one or more chemotherapeutic agents and / or one or more cancer vaccines.

[0108] In some embodiments, treating cancer with the anti-CD33 antibodies described herein involves (i) detecting tumor-infiltrating CD3 + (ii) expansion of T cell numbers, and (iii) non-tumorigenic CD14 + Reduction of cellular levels of CD33 in bone marrow cells, optionally in this case the non-tumorigenic CD14 + The myeloid cells may be tumor-infiltrating cells, or optionally, in this case, the non-tumorigenic CD14 + (iii) non-tumorigenic CD14 cells present in the blood + Reduction in bone marrow cell numbers, optionally in this case the non-tumorigenic CD14 + The myeloid cells may be tumor-infiltrating cells, or optionally, in this case, the non-tumorigenic CD14 +(iv) a reduction in PD-L1, PD-L2, B7-H2, B7-H3, CD200R, CD163, and / or CD206 levels in one or more cells, optionally where the one or more cells are non-tumorigenic myeloid-derived suppressor cells (MDSCs); (v) a reduction in tumor growth rate of a solid tumor; (vi) a reduction in tumor volume; (vii) an improvement in the efficacy of one or more PD-1 inhibitors; (viii) an improvement in the efficacy of one or more checkpoint inhibitor therapies and / or immunomodulatory therapies, optionally where the one or more checkpoint inhibitor therapies and / or immunomodulatory therapies target one or more of CTL4, adenosine pathway, PD-L1, PD-L2, OX40, TIM3, LAG-3, or any combination thereof; (ix) an improvement in the efficacy of one or more chemotherapeutic agents, optionally where the one or more chemotherapeutic agents are gemcitabine, capecitabine, or any combination thereof. Cytabine, anthracyclines, doxorubicin (Adriamycin®), epirubicin (Ellence®), taxanes, paclitaxel (Taxol®), docetaxel (Taxotere®), 5-fluorouracil (5-FU), cyclophosphamide (Cytoxan®), carboplatin (Paraplatin®), and any combination thereof, have the potential to (x) increase T cell proliferation in the presence of non-tumorigenic myeloid-derived suppressor cells (MDSCs), (xi) inhibit the differentiation, survival, and / or one or more functions of non-tumorigenic myeloid-derived suppressor cells (MDSCs), and (xii) when conjugated to a chemical or radiotoxin, kill CD33-expressing immunosuppressive non-tumorigenic myeloid cells and / or non-tumorigenic CD14-expressing cells in solid tumors and associated vasculature.

[0109] In some embodiments, the bone marrow cells of the present disclosure include, without limitation, CD45+CD14+ bone marrow cells, CD14+ bone marrow cells, and myeloid-derived suppressor cells (MDSCs). In some embodiments, the bone marrow cells of the present disclosure are non-tumorigenic bone marrow cells. Immunosuppressive cells may also be referred to as myeloid-derived suppressor cells (MDSCs). In humans, MDSCs can be defined by one of the following marker combinations: :(1)CD14+HLA-DR low / -, (2)CD14+IL4Rα+, (3)CD14+HLA-DR-IL4Rα+, (4)CD34+CD14+CD11b+CD33+, (5)CD11b+CD14+CD33+, (6)CD33+HL A-DR-, (7)Lin-HLA-DR-, (8)Lin-HLA-DR-CD33+, (9)Lin-HLA-DR-CD33+CD11b+, (10)Lin-CD33+CD11b+CD15+, (11)Lin-HLA-DR-CD33+ CD11b+CD14-CD15+, (12) CD11b+CD14-CD33+, (13) CD11b+CD14-HLA-DR-CD33+CD15+, (14) CD33+HLA-DR-CD15+, (15) CD15+IL4Rα+, (16) CD11b+CD15+CD66b+, (17) CD15+FSC-low SSC-high, (18) CD15-high CD33+, (19) CD11b+CD14-CD15+, (20) CD66b+SSC-high, and (21) CD11b+CD15+ (see also Solito S et al. Annals of the NY Academy of Sciences, 2014). In mice, MDSCs can be defined by the expression of the surface markers CD45+, CD11b+, Gr1+, and / or Il4Ra+. Further exemplary immunosuppressive monocyte lineages are CD45+, CD11b+, Gr1low, and CD45+, CD11c+.

[0110] CD33 protein In one aspect, the present disclosure provides antibodies, such as isolated (e.g., monoclonal) antibodies, that interact with or otherwise bind to a region, such as an epitope, within a CD33 protein of the disclosure. In some embodiments, the antibodies interact with or otherwise bind to a region, such as an epitope, within a CD33 protein of the disclosure with improved / enhanced kinetics (e.g., relative to an anti-CD33 antibody having a heavy chain variable region comprising the sequence of SEQ ID NO: 103 and a light chain variable region comprising the sequence of SEQ ID NO: 104). In some embodiments, the antibodies have a lower half maximal effective concentration (EC 50 ) interact with or otherwise bind to a region, such as an epitope, within the CD33 protein of a human cell, such as a dendritic cell. In some embodiments, the anti-CD33 antibodies of the present disclosure bind to the CD33 protein and, after binding to the CD33 protein, modulate one or more CD33 activities, e.g., activities associated with CD33 expression in a cell. CD33 proteins of the present disclosure include, without limitation, mammalian CD33 proteins, human CD33 proteins, mouse CD33 proteins, and rat CD33 proteins.

[0111] CD33 is variously referred to as CD33 molecule, Siglec3, Siglec-3, CD33 antigen (Gp67), P67, Gp67, sialic acid-binding Ig-like lectin 3, myeloid cell surface antigen CD33, or FLJ00391.

[0112] CD33 is an immunoglobulin-like receptor that is primarily expressed on cells of the myeloid lineage, including, without limitation, macrophages, dendritic cells, osteoclasts, monocytes, and microglia. In some embodiments, CD33 forms a receptor signaling complex with CD64. In some embodiments, CD33 signaling leads to downstream inhibition of PI3K or other intracellular signals. On myeloid cells, Toll-like receptor (TLR) signaling is important for inhibiting CD33 activity, for example, in terms of infection response. TLRs, for example, TLRs expressed on macrophages and dendritic cells, also play an important role in pathological inflammatory responses.

[0113] The amino acid sequence of human CD33 is set forth below as SEQ ID NO:1. TIFF2025176024000003.tif35170

[0114] In some embodiments, CD33 is a precursor protein that includes a signal sequence. In some embodiments, CD33 is a mature protein. In some embodiments, the mature CD33 protein does not include a signal sequence. In some embodiments, the mature CD33 protein is expressed on a cell. In some embodiments, the mature CD33 protein is expressed on a cell, e.g., on the cell surface, including, without limitation, human dendritic cells, human macrophages, human monocytes, human osteoclasts, human neutrophils, human T cells, human T helper cells, human cytotoxic T cells, human granulocytes, and human microglia. The anti-CD33 antibodies of the present disclosure can bind to any of the CD33 proteins of the present disclosure expressed on any of the cells disclosed herein.

[0115] The CD33 protein of the present disclosure, e.g., human CD33, comprises several domains, including, without limitation, a signal sequence located at amino acid residues 1-17 of SEQ ID NO: 1, an extracellular immunoglobulin-like variable (IgV) domain located at amino acid residues 19-135 of SEQ ID NO: 1, an Ig-like C2-type domain located at amino acid residues 145-228 of SEQ ID NO: 1, a transmembrane domain located at amino acid residues 260-282 of SEQ ID NO: 1, ITIM motif 1 located at amino acid residues 338-343 of SEQ ID NO: 1, and ITIM motif 2 located at amino acid residues 356-361 of SEQ ID NO: 1. As one of skill in the art will appreciate, the beginning and ending residues of the domains of the present disclosure may vary depending on the computer modeling program or method used to determine the domains.

[0116] Certain aspects of the present disclosure provide anti-CD33 antibodies that bind to human CD33 or homologs thereof, including, without limitation, mammalian CD33 proteins and CD33 orthologs from other species. In some embodiments, the anti-CD33 antibodies of the present disclosure bind to human CD33 or homologs thereof with improved / enhanced binding kinetics (e.g., relative to an anti-CD33 antibody having a heavy chain variable region comprising the sequence of SEQ ID NO: 103 and a light chain variable region comprising the sequence of SEQ ID NO: 104).

[0117] Thus, as used herein, the "CD33" protein of the present disclosure includes, without limitation, mammalian CD33 protein, human CD33 protein, primate CD33 protein, mouse CD33 protein, and rat CD33 protein. Furthermore, anti-CD33 antibodies of the present disclosure may bind to epitopes in human CD33 protein and primate CD33. In some embodiments, anti-CD33 antibodies of the present disclosure may specifically bind to human CD33.

[0118] In some embodiments, antibodies of the present disclosure may bind to CD33 in a pH-dependent manner. In some embodiments, antibodies of the present disclosure may bind to CD33 at neutral pH and may be internalized without dissociating from the CD33 protein. Alternatively, antibodies of the present disclosure may dissociate from CD33 upon internalization at acidic pH, followed by degradation via the endosomal / lysosomal pathway. In certain embodiments, anti-CD33 antibodies bind to CD33 at pH 5.5-8.0, 5.5-7.5, 5.5-7.0, 5.5-6.5, 5.5-6.0, 6.0-8.0, 6.5-8.0, 7.0-8.0, 7.5-8.0, 6.0-7.5, 6.0-7.0, or 6.5-7.5. In certain embodiments, the anti-CD33 antibody dissociates from CD33 at a pH below 6.0, below 5.5, below 5.0, below 4.5, below 4.0, below 3.5, below 3.0, below 2.5, or below 2.0.

[0119] In some embodiments, the antibodies of the present disclosure bind to a wild-type CD33 protein of the present disclosure, a naturally occurring variant thereof, and / or a disease variant thereof.

[0120] In some embodiments, antibodies of the disclosure bind to a variant of human CD33 comprising the single nucleotide polymorphism (SNP) rs3865444C at nucleotide (C). In some embodiments, antibodies of the disclosure that reduce cellular levels of CD33 and / or bind to or interact with CD33 bind to a variant of human CD33 comprising the single nucleotide polymorphism (SNP) rs3865444C at nucleotide (A). In some embodiments, anti-CD33 antibodies of the disclosure bind to a variant of human CD33 comprising the single nucleotide polymorphism (SNP) rs3865444 at nucleotide (A). AC or rs3865444 CC Binds to variants containing

[0121] In some embodiments, antibodies of the disclosure that reduce cellular levels of CD33 and / or bind to or interact with CD33 bind to a variant of human CD33 that includes SNP rs35112940 at a GG, AA, or AG nucleotide. In some embodiments, antibodies of the disclosure that reduce cellular levels of CD33 and / or bind to or interact with CD33 bind to a variant of human CD33 that includes SNP rs12459419 at a CC, CT, or TT genotype. In certain embodiments, the subject is homozygous or heterozygous for the coding SNP rs1803 at a GG, CG, or CC nucleotide.

[0122] In some embodiments, antibodies of the present disclosure that reduce cellular levels of CD33 and / or bind to or interact with CD33 bind to CD33 protein expressed on the surface of cells, including, without limitation, human dendritic cells, human macrophages, human monocytes, human osteoclasts, human neutrophils, human T cells, human T helper cells, human cytotoxic T cells, human granulocytes, and human microglia. In some embodiments, antibodies of the present disclosure that reduce cellular levels of CD33 and / or bind to or interact with CD33 bind to CD33 protein expressed on the cell surface and modulate (e.g., induce or inhibit) at least one CD33 activity of the present disclosure after binding to the surface-expressed CD33 protein. In some embodiments of the present disclosure, the anti-CD33 antibody specifically binds to CD33 protein. In some embodiments of the present disclosure, the anti-CD33 antibody further binds to at least one additional Siglec protein. In some embodiments, the anti-CD33 antibody modulates one or more activities of the at least one additional Siglec protein or one or more activities of a cell expressing the at least one additional Siglec protein.

[0123] CD33 Ligand The CD33 proteins of the present disclosure can interact with (eg, bind to) one or more CD33 ligands.

[0124] Exemplary CD33 ligands include, without limitation, sialic acid, sialic acid-containing glycolipids, sialic acid-containing glycoproteins, alpha-2,6-linked sialic acid-containing glycolipids, alpha-2,6-linked sialic acid-containing glycoproteins, alpha-2,3-linked sialic acid-containing glycolipids, alpha-2,3-linked sialic acid-containing glycoproteins, alpha-1 acid glycoprotein (AGP), CD24 protein, gangliosides (e.g., glycolipids comprising a ceramide attached to a sialylated glycan), secreted mucins, CD33 ligand expressed on erythrocytes, CD33 ligand expressed on bacterial cells, CD33 ligand expressed on apoptotic cells, CD33 ligand expressed on tumor cells, CD33 ligand expressed on viruses, CD33 ligand expressed on dendritic cells, CD33 ligand expressed on neuronal cells, CD33 ligand expressed on glial cells, Examples of CD33 ligands include CD33 ligands expressed on microglia, CD33 ligands expressed on astrocytes, CD33 ligands on beta-amyloid plaques, CD33 ligands on tau tangles, CD33 ligands on pathogenic proteins, CD33 ligands on pathogenic peptides, CD33 ligands expressed on macrophages, CD33 ligands expressed on natural killer cells, CD33 ligands expressed on T cells, CD33 ligands expressed on T helper cells, CD33 ligands expressed on cytotoxic T cells, CD33 ligands expressed on B cells, CD33 ligands expressed on tumor-buried immunosuppressive dendritic cells, CD33 ligands expressed on tumor-buried immunosuppressive macrophages, CD33 ligands expressed on myeloid-derived suppressor cells, and CD33 ligands expressed on regulatory T cells. In some embodiments, the CD33 ligands of the present disclosure are gangliosides. Gangliosides generally share a common lacto-ceramide core and one or more sialic acid residues.

[0125] Further examples of suitable ganglioside ligands are listed in Table A. In general, gangliosides are molecules consisting of glycosphingolipids with one or more sialic acids (e.g., n-acetylneuraminic acid, NANA) attached to the sugar chain. TIFF2025176024000004.tif237170

[0126] CD33 antibody Certain aspects of the present disclosure relate to anti-CD33 antibodies comprising one or more improved and / or enhanced functional properties. In some embodiments, the anti-CD33 antibodies of the present disclosure comprise one or more improved and / or enhanced functional properties relative to a control antibody (e.g., a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77, a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 52 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, and / or a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 103 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 104). In some embodiments, the anti-CD33 antibodies of the present disclosure have a higher affinity for CD33 (e.g., human CD33) than a control anti-CD33 antibody (e.g., a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77, a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, and a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 52 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, and / or a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 103 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 104). In some embodiments, an anti-CD33 antibody of the disclosure has a lower half maximal effective concentration (EC) than that of a control antibody (e.g., a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77, a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, and a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 52 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, and / or a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 103 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 104). 50In some embodiments, the anti-CD33 antibodies of the present disclosure bind to human cells, such as dendritic cells, at a lower half maximal effective concentration (EC ) than that of a control antibody (e.g., a control anti-CD33 antibody comprising a heavy chain variable region comprising the sequence of SEQ ID NO: 103 and a light chain variable region comprising the sequence of SEQ ID NO: 104). 50 ) to reduce cellular levels (e.g., cell surface levels) of CD33.

[0127] Cellular levels of CD33 can refer, without limitation, to cell surface CD33 levels, intracellular CD33 levels, and total CD33 levels. In some embodiments, reducing cellular levels of CD33 includes reducing cell surface CD33 levels. In some embodiments, anti-CD33 antibodies of the present disclosure that reduce cellular levels of CD33 (e.g., cell surface CD33 levels) have one or more of the following properties: (1) inhibiting or reducing one or more CD33 activities, (2) the ability to inhibit or reduce binding of CD33 to one or more of its ligands, (3) the ability to reduce CD33 expression in CD33-expressing cells, (4) the ability to interact with, bind to, or recognize CD33 protein, (5) the ability to specifically interact with or bind to CD33 protein, and (6) the ability to treat, ameliorate, or prevent any aspect of a disease or disorder described or contemplated herein.

[0128] The anti-CD33 antibodies of the present disclosure may have nanomolar or even picomolar affinities for the target antigen (e.g., human CD33). In certain embodiments, the dissociation constant (K D ) is about 0.001 to about 100 nM. In certain embodiments, the K D In certain embodiments, the K of the antibody is about 0.01 to about 10 nM. D In some embodiments, the K of the antibody is about 0.202 to about 8.57 nM. Dis about 100 nM, 90 nM, 80 nM, 70 nM, 60 nM, 50 nM, 40 nM, 30 nM, 20 nM, 10 nM, 9.5 nM, 9 nM, 8.5 nM, 8 nM, 7.5 nM, 7 nM, 6.5 nM, 6 nM, 5.5 nM, 5 nM, 4.5 nM, 4 nM, 3.5 nM, 3 nM, 2.5 nM, 2 nM, 1.5 nM, 1 nM, 0.9 nM, 0.8 nM, 0.7 nM, 0.6 nM, 0.5 nM, 0.4 nM, 0.3 nM, 0.2 nM, 0.1 nM, 0.05 nM, 0.01 nM, or 0.005 nM or less. D In some embodiments, the K of the antibody is less than about 5.22 nM. D is about 0.001 nM, 0.005 nM, 0.01 nM, 0.05 nM, 0.1 nM, 0.2 nM, 0.3 nM, 0.4 nM, 0.5 nM, 0.6 nM, 0.7 nM, 0.8 nM, 0.9 nM, 1 nM, 1.5 nM, 2 nM, 2.5 nM, 3 nM, 3.5 nM, 4 nM, 4.5 nM, 5 nM, 5.5 nM, 6 nM, 6.5 nM, 7 nM, 7.5 nM, 8 nM, 8.5 nM, 9 nM, 9.5 nM, 10 nM, 20 nM, 30 nM, 40 nM, 50 nM, 60 nM, 70 nM, 80 nM, or 90 nM or more. Dis an upper limit of about 100nM, 90nM, 80nM, 70nM, 60nM, 50nM, 40nM, 30nM, 20nM, 10nM, 9.5nM, 9nM, 8.5nM, 8nM, 7.5nM, 7nM, 6.5nM, 6nM, 5.5nM, 5nM, 4.5nM, 4nM, 3.5nM, 3nM, 2.5nM, 2nM, 1.5nM, 1nM, 0.9nM, 0.8nM, 0.7nM, 0.6nM, 0.5nM, 0.4nM, 0.3nM, 0.2nM, 0.1nM, 0.05nM, 0.01nM, or 0.005nM, and an independently selected lower limit of about. The affinity range may be any of the following: 0.001 nM, 0.005 nM, 0.01 nM, 0.05 nM, 0.1 nM, 0.2 nM, 0.3 nM, 0.4 nM, 0.5 nM, 0.6 nM, 0.7 nM, 0.8 nM, 0.9 nM, 1 nM, 1.5 nM, 2 nM, 2.5 nM, 3 nM, 3.5 nM, 4 nM, 4.5 nM, 5 nM, 5.5 nM, 6 nM, 6.5 nM, 7 nM, 7.5 nM, 8 nM, 8.5 nM, 9 nM, 9.5 nM, 10 nM, 20 nM, 30 nM, 40 nM, 50 nM, 60 nM, 70 nM, 80 nM, or 90 nM, where the lower limit is lower than the upper limit. In some embodiments, the K of the antibody may be any of the following: D is about 10 nM, about 9 nM, about 8 nM, about 7 nM, about 6 nM, about 5 nM, about 4 nM, about 3 nM, about 2 nM, about 1 nM, about 900 pM, about 800 pM, about 700 pM, about 600 pM, about 500 pM, about 400 pM, about 300 pM, about 200 pM, or about 100 pM. Various methods for measuring antibody affinity are known in the art, including, for example, the use of surface plasmon resonance or BioLayer interferometry (see, e.g., Example 1 below). In some embodiments, the K for CD33 is D is measured at a temperature of about 25° C. In some embodiments, the K D is measured at a temperature of about 4° C. In some embodiments, the K D is measured using a monovalent antibody (e.g., a Fab) or a full-length antibody in a monovalent form. D is measured using bivalent antibodies and monomeric recombinant CD33 protein.

[0129] In some embodiments, the anti-CD33 antibodies of the present disclosure have a dissociation constant (K D ) is lower than a control anti-CD33 antibody (e.g., a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77, a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, and a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 52 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, and / or a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 103 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 104). In some embodiments, the anti-CD33 antibodies of the present disclosure have a K D is a K for the target of a control anti-CD33 antibody (e.g., a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77, a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 52 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, and / or a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 103 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 104). D In some embodiments, the anti-CD33 antibodies of the present disclosure have a K for a target (e.g., human CD33) that is at least about 5%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, 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%, or at least about 99% lower. Dis a K for the target of a control anti-CD33 antibody (e.g., a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77, a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 52 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, and / or a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 103 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 104). D In some embodiments, the anti-CD33 antibodies of the present disclosure have a K for human CD33 that is at least about 1 fold, at least about 1.1 fold, at least about 1.5 fold, at least about 2 fold, at least about 3 fold, at least about 4 fold, at least about 5 fold, at least about 6 fold, at least about 7 fold, at least about 8 fold, at least about 9 fold, at least about 10 fold, at least about 12.5 fold, at least about 15 fold, at least about 17.5 fold, at least about 20 fold, at least about 22.5 fold, at least about 25 fold, at least about 27.5 fold, at least about 30 fold, at least about 50 fold, or at least about 100 fold lower. D is at least 9-fold higher than an anti-CD33 antibody having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77. In some embodiments, the anti-CD33 antibodies of the present disclosure have a K D is at least 3-fold higher than an anti-CD33 antibody having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86. In some embodiments, the anti-CD33 antibodies of the present disclosure have a K Dis at least three-fold higher than an anti-CD33 antibody having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:52 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:86. In some embodiments, the affinity is measured by surface plasmon resonance. In some embodiments, the affinity is measured at a temperature of about 25°C. In some embodiments, the affinity is measured at a temperature of about 4°C. In some embodiments, the affinity is measured using the experimental methods described in Example 1 below.

[0130] The anti-CD33 antibodies of the present disclosure have half maximal effective concentrations (EC 50 ) may reduce cellular levels (e.g., cell surface levels) of CD33 (e.g., as measured in vitro using primary human dendritic cells). In certain embodiments, the EC 50 In certain embodiments, the EC 50 In certain embodiments, the EC 50 In some embodiments, the EC 50 is about 500 pM, 400 pM, 300 pM, 250 pM, 225 pM, 200 pM, 175 pM, 150 pM, 125 pM, 100 pM, 75 pM, 50 pM, 25 pM, 10 pM, 1 pM, or 0.5 pM or less. 50 In some embodiments, the EC 50 is about 0.1 pM, 0.5 pM, 1 pM, 10 pM, 25 pM, 50 pM, 75 pM, 100 pM, 125 pM, 150 pM, 175 pM, 200 pM, 225 pM, 250 pM, 300 pM, or 400 pM or more. 50can be anywhere in a range having an upper limit of about 500 pM, 400 pM, 300 pM, 250 pM, 225 pM, 200 pM, 175 pM, 150 pM, 125 pM, 100 pM, 75 pM, 50 pM, 25 pM, 10 pM, 1 pM, or 0.5 pM, and an independently selected lower limit of about 0.1 pM, 0.5 pM, 1 pM, 10 pM, 25 pM, 50 pM, 75 pM, 100 pM, 125 pM, 150 pM, 175 pM, 200 pM, 225 pM, 250 pM, 300 pM, or 400 pM, where the lower limit is lower than the upper limit. In some embodiments, the EC 50 is approximately 1pM, 2pM, 3pM, 4pM, 5pM, 6pM, 7pM, 8pM, 9pM, 10pM, 15pM, 20pM, 25pM, 30pM, 35pM, 40pM, 45pM, 50pM, 55pM, 60pM, 65pM, 70pM, 75pM, 80pM, 85pM, 90pM, 95pM, 100p EC50 of the antibody is 100 pM, 105 pM, 110 pM, 115 pM, 120 pM, 125 pM, 130 pM, 135 pM, 140 pM, 145 pM, 150 pM, 155 pM, 160 pM, 165 pM, 170 pM, 175 pM, 180 pM, 185 pM, 190 pM, 195 pM, or 200 pM. 50 Various methods of measuring EC levels are known in the art, including, for example, by flow cytometry (see, e.g., Example 2 below). 50 is measured in vitro using primary human dendritic cells. In some embodiments, the EC 50 is measured in vitro using primary human monocytes. In some embodiments, the EC 50 is measured in vitro using primary human macrophages. In some embodiments, the EC 50 is measured in vitro using cultured cells transfected with human CD33. In some embodiments, the EC 50 is measured at a temperature of about 4° C. In some embodiments, the EC 50 is measured at a temperature of about 25° C. In some embodiments, the EC 50 is measured at a temperature of about 35° C. In some embodiments, the EC 50is measured at a temperature of about 37° C. In some embodiments, the EC 50 is measured using a monovalent antibody (e.g., a Fab) or a full-length antibody in a monovalent form. In some embodiments, the EC 50 is measured using an antibody comprising a constant region that exhibits improved Fc receptor binding. 50 is measured using antibodies containing constant regions that exhibit reduced Fc receptor binding.

[0131] In some embodiments, an anti-CD33 antibody of the present disclosure has a lower EC than a control anti-CD33 antibody (e.g., a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77, a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, and a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 52 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, and / or a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 103 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 104). 50 In some embodiments, the anti-CD33 antibodies of the present disclosure reduce cellular levels (e.g., cell surface levels) of CD33 at 100 ng / mL (e.g., as measured in vitro using primary human dendritic cells). ... vivo using primary human dendritic cells). In some embodiments, the anti-CD33 antibodies of the present disclosure reduce cellular levels (e.g 50at least about 5%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, 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%, or at least about 99% lower EC 50 In some embodiments, the anti-CD33 antibodies of the present disclosure reduce the cellular levels (e.g., cell surface levels) of CD33 by a factor greater than or equal to the EC of a control anti-CD33 antibody (e.g., a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77, a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 52 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, and / or a control anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 103 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 104). 50 at least about 1 fold, at least about 1.1 fold, at least about 1.5 fold, at least about 2 fold, at least about 3 fold, at least about 4 fold, at least about 5 fold, at least about 6 fold, at least about 7 fold, at least about 8 fold, at least about 9 fold, at least about 10 fold, at least about 12.5 fold, at least about 15 fold, at least about 17.5 fold, at least about 20 fold, at least about 22.5 fold, at least about 25 fold, at least about 27.5 fold, at least about 30 fold, at least about 50 fold, or at least about 100 fold lower EC 50 In some embodiments, the anti-CD33 antibodies of the present disclosure inhibit EC 50 is at least 1.6-fold lower than an anti-CD33 antibody having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77. In some embodiments, the anti-CD33 antibodies of the present disclosure have an EC 50is at least 1.05-fold lower than an anti-CD33 antibody having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86. In some embodiments, the anti-CD33 antibodies of the present disclosure have an EC 50 is at least 1.07-fold lower than an anti-CD33 antibody having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 52 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86. In some embodiments, the anti-CD33 antibodies of the present disclosure have an EC 50 is at least 1.2-fold lower than an anti-CD33 antibody having a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 103 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 104. In some embodiments, the EC 50 is measured in vitro using primary human dendritic cells. In some embodiments, the EC 50 is measured in vitro using primary human monocytes. In some embodiments, the EC 50 is measured in vitro using primary human macrophages. In some embodiments, the EC 50 is measured in vitro using cultured cells transfected with human CD33. In some embodiments, the EC 50 is measured by flow cytometry. 50 is measured at a temperature of about 25° C. In some embodiments, the EC 50 is measured at a temperature of about 35° C. In some embodiments, the EC 50 is measured at a temperature of about 37° C. In some embodiments, the EC 50 is measured using an antibody comprising a constant region that exhibits improved Fc receptor binding. 50 is measured using an antibody comprising a constant region that exhibits reduced Fc receptor binding. 50 is measured using the experimental method described in Example 2 below.

[0132] Inhibition of the interaction (e.g., binding) between CD33 and one or more CD33 ligands may be measured using any in vitro cell-based assay or suitable in vivo model described herein or known in the art. In some embodiments, the anti-CD33 antibodies of the disclosure inhibit the interaction (e.g., binding) between CD33 and one or more CD33 ligands by at least 21%, at least 22%, at least 23%, at least 24%, at least 25%, at least 26%, at least 27%, at least 28%, at least 29%, at least 30%, at least 31%, at least 32%, at least 33%, at least 34%, at least 35%, at least 36%, at least 37%, at least 38%, at least 39%, at least 40%, at least 41%, at least 42%, at least 43%, at least 44%, at least 45%, at least 46%, at least 47%, at least 48%, at least 49%, at least 50%, at least 51%, at least 52%, at least 53%, at least 54%, at least 55%, at least 56%, at least 57%, at least 58%, at least 59%, at least 60%, at least 61%, at least 62%, at least 63%, at least 64%, at least 65%, at least 66%, at least 67%, at least 68%, at least 69%, at least 70%, at least 71%, at least 72%, at least 73%, at least 74%, at least 75%, at least 76%, at least 77%, at least 78%, at least 79%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 9 at least 54%, at least 55%, at least 56%, at least 57%, at least 58%, at least 59%, at least 60%, at least 61%, at least 62%, at least 63%, at least 64%, at least 65%, at least 66%, at least 67%, at least 68%, at least 69%, at least 70%, at least 71%, at least 72%, at least 73%, at least 74%, at least 75%, at least 76%, at least 77%, at least 78%, at least 79%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or more.

[0133] In some embodiments, the anti-CD33 antibodies of the present disclosure inhibit cell surface clustering of CD33. In some embodiments, the anti-CD33 antibodies of the present disclosure inhibit one or more of, but are not limited to, disrupting phosphorylation of Tyr-340 and Tyr-358 by Src family tyrosine kinases such as LCK and FYN, recruiting and binding to tyrosine-specific protein phosphatases SHP1 and SHP2, recruiting and binding to PLC-gamma 1, which acts as a guanine nucleotide exchange factor for Dynamini-1, recruiting and binding to SH2 domain-containing proteins (e.g., Crkl), and spleen tyrosine kinase Syk. recruitment and binding of SH3-SH2-SH3 growth factor receptor-bound protein 2 (Grb2); recruitment and binding of multiple SH2-containing proteins; phosphorylation of Ser-307 and Ser-342 by protein kinase C; and expression of soluble receptors for one or more anti-inflammatory cytokines, IL-4, IL-10, IL-13, IL-35, IL-16, TGF-beta, IL-1Ra, G-CSF, and TNF, IFN-beta 1a, IFN-beta 1b, or IL-6, in monocytes and macrophages. , regulated expression in T cells, dendritic cells, neutrophils, and / or microglia, decreased intracellular calcium mobilization, and increased expression of one or more of the proinflammatory cytokines IFN-α4, IFN-b, IL-1β, TNF-α, IL-6, IL-8, CRP, IL-20 family members, LIF, IFN-gamma, OSM, CNTF, GM-CSF, IL-11, IL-12, IL-17, IL-18, IL-23, CXCL10, IL-33, CRP, IL-33, MCP-1, and MIP-1-beta in monocytes, macrophages, T cells, dendritic cells, neutrophils, and / or microglia. regulated expression in cells, neutrophils, and / or microglia of one or more proteins selected from C1qa, C1qB, C1qC, C1s, C1R, C4, C2, C3, ITGB2, HMOX1, LAT2, CASP1, CSTA, VSIG4, MS4A4A, C3AR1, GPX1, TyroBP, ALOX5AP, ITGAM, SLC7A7, CD4, ITGAX, PYCARD, CD14, CD16, HLA-DR, and CCR2; inhibition of phosphorylation of extracellular signal-regulated kinase (ERK);Decreased tyrosine phosphorylation of multiple cellular proteins, regulated expression of CC chemokine receptor 7 (CCR7), inhibition of microglial cell chemotaxis toward CCL19- and CCL21-expressing cells, activation of phosphoinositide 3-kinase, decreased proliferation of monocytes, macrophages, T cells, dendritic cells, and / or microglia, dendritic cells, bone marrow-derived dendritic cells, monocytes, microglia, M1 microglia, activated M1 microglia, M2 microglia, macrophages, M1 macrophages, activated M1 macrophages, and / or M2 macrophages. reduction of T cell proliferation, inhibition of osteoclast production, reduction of osteoclast formation rate, or both, neutrophils, dendritic cells, bone marrow-derived dendritic cells, macrophages, M1 macrophages, activated M1 macrophages, M2 macrophages, monocytes, osteoclasts, T cells, T helper cells, cytotoxic T cells, granulocytes, microglia, M1 microglia, activated M1 microglia, and / or M2 microglia, ... reduction of proliferation of neutrophils, monocytes, osteoclasts, T cells, T helper cells, cytotoxic T cells, granulocytes, microglia, M1 microglia, activated M1 microglia, and / or M2 microglia; inhibition of migration of neutrophils, dendritic cells, bone marrow-derived dendritic cells, macrophages, M1 macrophages, activated M1 macrophages, M2 macrophages, monocytes, osteoclasts, T cells, T helper cells, cytotoxic T cells, granulocytes, microglia, M1 microglia, activated M1 microglia, and / or M2 microglia; a reduction in one or more functions of neutrophils, dendritic cells, bone marrow-derived dendritic cells, macrophages, M1 macrophages, activated M1 macrophages, M2 macrophages, monocytes, osteoclasts, T cells, T helper cells, cytotoxic T cells, granulocytes, microglia, M1 microglia, activated M1 microglia, and / or M2 microglia; a reduction in one or more functions of neutrophils, dendritic cells, bone marrow-derived dendritic cells, macrophages, M1 macrophages, activated M1 macrophages, M2 macrophages, monocytes, osteoclasts, T cells, T helper cells, cytotoxic T cells, granulocytes, microglia, M1 microglia, activated M1 microglia, and / or M2 microglia;and / or inhibition of M2 microglia maturation, increased cell death and apoptosis of monocytes, macrophages, T cells, dendritic cells, neutrophils, and / or microglia, decreased phagocytic activity of monocytes, macrophages, T cells, dendritic cells, neutrophils, and / or microglia, decreased proliferation of monocytes, macrophages, T cells, dendritic cells, neutrophils, and / or microglia, decreased overall function of monocytes, macrophages, T cells, dendritic cells, neutrophils, and / or microglia, phosphorylation of ITAM-containing receptors, signaling molecules mediating ITAM signaling phosphorylation of CD33, reducing activation of pattern recognition receptors, reducing activation of Toll-like receptors, reducing activation of clearance of damage-related cellular and protein debris, interaction between CD33 and one or more of its ligands, interaction between CD33 and coreceptors such as CD64, removal of apoptotic neurons, removal of neural tissue debris, removal of dysfunctional synapses, removal of non-neural tissue debris, removal of bacteria or other foreign bodies, removal of pathogenic proteins, and removal of tumor cells, apoptotic neurons, neural tissue debris, non-neural tissue debris, Inhibition of phagocytosis of one or more of bacteria, other foreign bodies, pathogenic proteins, pathogenic peptides, pathogenic nucleic acids, pathogenic lipids, or tumor cells, e.g., inhibition of removal of pathogenic nucleic acids, e.g., where the pathogenic nucleic acid is an antisense GGCCCC (G2C4) repeat expansion RNA, amyloid beta, amyloid beta plaques, amyloid precursor protein or fragments thereof, tau, IAPP, alpha-synuclein, TDP-43, FUS protein, C9orf72 (chromosome 9 open reading frame 72), c9RAN protein, prion protein, PrPSc, huntingtin, calcitonin , superoxide dismutase, ataxin, ataxin 1, ataxin 2, ataxin 3, ataxin 7, ataxin 8, ataxin 10, Lewy bodies, atrial natriuretic factor, islet amyloid polypeptide, insulin, apolipoprotein AI, serum amyloid A, medin, prolactin, transthyretin, lysozyme, beta-2 microglobulin, gelsolin, keratoepithelin, cystatin, immunoglobulin light chain AL, S-IBM protein, repeat-associated non-ATG (RAN) translation products, dipeptide repeat (DPR) peptides,Activation of elimination of pathogenic proteins selected from glycine-alanine (GA) repeat peptides, glycine-proline (GP) repeat peptides, glycine-arginine (GR) repeat peptides, proline-alanine (PA) repeat peptides, ubiquitin, and proline-arginine (PR) repeat peptides, beneficial immunity against different types of cancer selected from bladder cancer, brain cancer, breast cancer, colon cancer, rectal cancer, endometrial cancer, kidney cancer, renal cell carcinoma, renal pelvis cancer, leukemia, lung cancer, melanoma, non-Hodgkin's lymphoma, acute myeloid leukemia, pancreatic cancer, prostate cancer, ovarian cancer, fibrosarcoma, and thyroid cancer. Response inhibition, dementia, frontotemporal dementia, Alzheimer's disease, vascular dementia, mixed dementia, Creutzfeldt-Jakob disease, normal pressure hydrocephalus, amyotrophic lateral sclerosis, Huntington's disease, taupathy, Nasu-Hakola disease, stroke, acute trauma, chronic trauma, essential tremor, Behçet's disease, Parkinson's disease, dementia with Lewy bodies, multiple system atrophy, Shy-Drager syndrome, progressive supranuclear palsy, corticobasal ganglionic degeneration, acute disseminated encephalomyelitis, granulomatous disease, sarcoidosis, age-related diseases, seizures, spinal cord injury, traumatic brain injury, age-related macular degeneration, glaucoma, retinal pigment epithelium inhibition of beneficial immune responses against different types of inflammation and infections selected from lupus, acute and chronic colitis, wound healing, Crohn's disease, inflammatory bowel disease, ulcerative colitis, obesity, malaria, respiratory tract infections, sepsis, eye infections, systemic infections, lupus, arthritis, low bone mineral density, osteoporosis, bone formation, osteopetrosis, and Paget's disease of bone; binding to CD33 ligand on tumor cells, dendritic cells, bone marrow-derived dendritic cells, monocytes, microglia, T cells, neutrophils, and / or or binding to CD33 ligand on macrophages; inhibiting tumor cell killing by one or more of microglia, macrophages, dendritic cells, bone marrow-derived dendritic cells, neutrophils, T cells, T helper cells, or cytotoxic T cells; inhibiting the anti-tumor cell proliferation activity of one or more of microglia, macrophages, dendritic cells, bone marrow-derived dendritic cells, neutrophils, T cells, T helper cells, or cytotoxic T cells; inhibiting the anti-tumor cell metastasis activity of one or more of microglia, macrophages, dendritic cells, bone marrow-derived dendritic cells, neutrophils, T cells, T helper cells, or cytotoxic T cells;promotion of immunosuppressive dendritic cells, immunosuppressive macrophages, myeloid-derived suppressor cells, tumor-associated macrophages, or regulatory T cells; inhibition of one or more ITAM motif-containing receptors, e.g., TREM1, TREM2, FcgR, DAP10, and DAP12; inhibition of one or more receptors containing the motif D / Ex0-2YxxL / IX6-8YxxL / I (SEQ ID NO: 165); inhibition of signaling by one or more pattern recognition receptors (PRRs), e.g., receptors that recognize pathogen-associated molecular patterns (PAMPs) and receptors that recognize damage-associated molecular patterns (DAMPs); inhibition of signaling by one or more Toll-like receptors; inhibiting one or more CD33 protein activities, including inhibiting the delivery pathway, inhibiting nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB), inhibiting PLCγ / PKC / calcium mobilization, inhibiting PI3K / Akt, Ras / MAPK signaling, reducing the expression of one or more inflammatory receptors, e.g., CD86, expressed on one or more of microglia, macrophages, dendritic cells, bone marrow-derived dendritic cells, neutrophils, T cells, T helper cells, or cytotoxic T cells, increasing the expression of one or more CD33-dependent genes, normalizing disrupted CD33-dependent gene expression, and reducing the expression of one or more ITAM-dependent genes, e.g., NFAT transcription factors;

[0134] In some embodiments, the anti-CD33 antibodies of the present disclosure include, without limitation, tumor-infiltrating CD3 + Increased T cell count, CD14 + Myeloid cells, e.g., tumor-infiltrating CD14 + CD14 in bone marrow cells and blood + Reduced cellular levels of CD33, CD14 in bone marrow cells + Myeloid cells, e.g., tumor-infiltrating CD14 + CD14 in bone marrow cells and blood +a reduction in the number of myeloid cells, a reduction in PD-L1, PD-L2, B7-H7, B7-H3, CD200R, CD163, and / or CD206 levels in one or more cells, e.g., myeloid-derived suppressor cells (MDSCs); a reduction in tumor growth rate of solid tumors; a reduction in tumor volume; an improvement in the efficacy of one or more PD-1 inhibitors; an improvement in the efficacy of one or more checkpoint inhibitor therapy and / or immunomodulatory therapy, e.g., checkpoint inhibitor therapy and / or immunomodulatory therapy targeting one or more of CTL4, the adenosine pathway, PD-L1, PD-L2, OX40, TIM3, LAG-3, or any combination thereof; an improvement in the efficacy of one or more chemotherapeutic agents, optionally wherein the one or more chemotherapeutic agents are gemcitabine, capecitabine, an anthracycline, doxorubicin (Adriamycin®), epirubicin (Ellence®), tachycardia (TCM®), cyclosporine (Cyclosporin ... San, paclitaxel (Taxol®), docetaxel (Taxotere®), 5-fluorouracil (5-FU), cyclophosphamide (Cytoxan®), carboplatin (Paraplatin®), oxaliplatin (Elotaxin®), leucovorin, temazolamide (Temodar®), and any combination thereof, exhibit one or more CD33 protein activities, including increasing T cell proliferation in the presence of myeloid-derived suppressor cells (MDSCs), inhibiting the differentiation, survival, and / or one or more functions of myeloid-derived suppressor cells (MDSCs), and killing CD33-expressing immunosuppressive non-tumorigenic myeloid cells and / or non-tumorigenic CD14-expressing cells in solid tumors and associated vasculature when conjugated to chemical or radiotoxins.

[0135] In some embodiments, the anti-CD33 antibody inhibits the interaction (e.g., binding) between a CD33 protein of the present disclosure and one or more CD33 ligands, including, without limitation, a CD33 ligand expressed on erythrocytes, a CD33 ligand expressed on bacterial cells, a CD33 ligand expressed on apoptotic cells, a CD33 ligand expressed on tumor cells, a CD33 ligand expressed on viruses, a CD33 ligand expressed on dendritic cells, a CD33 ligand expressed on neurons, a CD33 ligand expressed on glial cells, a CD33 ligand expressed on microglia, a CD33 ligand expressed on astrocytes, a CD33 ligand on beta-amyloid plaques, a CD33 ligand on tau tangles, a CD33 ligand on pathogenic proteins, a CD33 ligand on pathogenic peptides, a CD33 ligand expressed on macrophages, Ligands include CD33 ligand expressed on natural killer cells, CD33 ligand expressed on T cells, CD33 ligand expressed on T helper cells, CD33 ligand expressed on cytotoxic T cells, CD33 ligand expressed on B cells, CD33 ligand expressed on tumor-buried immunosuppressive dendritic cells, CD33 ligand expressed on tumor-buried immunosuppressive macrophages, CD33 ligand expressed on myeloid-derived suppressor cells, CD33 ligand expressed on regulatory T cells, secreted mucin, sialic acid, sialic acid-containing glycolipids, sialic acid-containing glycoproteins, alpha-2,6-linked sialic acid-containing glycolipids, alpha-2,6-linked sialic acid-containing glycoproteins, alpha-2,3-linked sialic acid-containing glycolipids, alpha-2,3-linked sialic acid-containing glycoproteins, alpha-1 acid glycoprotein (AGP), CD24 protein, and gangliosides.

[0136] In some embodiments, an anti-CD33 antibody of the present disclosure binds to a CD33 protein of the present disclosure expressed on the cell surface, and the naked antibody inhibits the interaction (e.g., binding) between the CD33 protein and one or more CD33 ligands. In some embodiments, an anti-CD33 antibody of the present disclosure that binds to the CD33 protein inhibits the interaction (e.g., binding) between the CD33 protein and one or more CD33 ligands by reducing the effective level of CD33 available for interaction with these proteins on the cell surface or inside the cell. In some embodiments, an anti-CD33 antibody of the present disclosure that binds to the CD33 protein inhibits the interaction (e.g., binding) between the CD33 protein and one or more CD33 ligands by inducing degradation of CD33.

[0137] As used herein, the level of CD33 may refer to the expression level of the gene encoding CD33, the expression level of one or more transcripts encoding CD33, the expression level of CD33 protein, and / or the amount of CD33 protein present in cells and / or on the cell surface. The level of CD33 can be measured using any method known in the art for measuring the levels of gene expression, transcription, translation, and / or protein amount or localization.

[0138] Additionally, the anti-CD33 antibodies of the present disclosure are useful in the treatment of dementia, frontotemporal dementia, Alzheimer's disease, vascular dementia, mixed dementia, Creutzfeldt-Jakob disease, normal pressure hydrocephalus, amyotrophic lateral sclerosis, Huntington's disease, tauopathy, Nasu-Hakola disease, stroke, acute trauma, chronic trauma, lupus, acute and chronic colitis, rheumatoid arthritis, wound healing, Crohn's disease, inflammatory bowel disease, and ulcerative colitis. , obesity, malaria, essential tremor, central nervous system lupus, Behçet's disease, Parkinson's disease, dementia with Lewy bodies, multiple system atrophy, Shy-Drager syndrome, progressive supranuclear palsy, corticobasal ganglionic degeneration, acute disseminated encephalomyelitis, granulomatous disease, sarcoidosis, age-related illnesses, stroke, spinal cord injury, traumatic brain injury, age-related macular degeneration, glaucoma, retinitis pigmentosa, retinal degeneration , respiratory tract infections, sepsis, eye infections, systemic infections, lupus, arthritis, multiple sclerosis, low bone density, osteoporosis, bone formation, osteopetrosis, Paget's disease of bone, cancers such as bladder cancer, brain cancer, breast cancer, colon cancer, rectal cancer, endometrial cancer, kidney cancer, renal cell carcinoma, renal pelvis cancer, leukemia, lung cancer, melanoma, non-Hodgkin's lymphoma, pancreatic cancer, prostate cancer, ovarian cancer, fibrosarcoma, acute lymphoblastic leukemia (ALL), acute It can be used to prevent, reduce the risk of, or treat myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), chronic myelogenous leukemia (CML), multiple myeloma, polycythemia vera, essential thrombocythemia, primary or idiopathic myelofibrosis, primary or idiopathic myelosclerosis, bone marrow derived tumors, tumors expressing CD33, thyroid cancer, infectious diseases, CNS herpes, parasitic infections, Trypanosoma infections, Trypanosoma cruzi infections, Pseudomonas aeruginosa infections, Leishmania donovani infections, Streptococcus group B infections, Campylobacter jejuni infections, Neisseria meningiditis infections, HIV type 1, and / or Haemophilus influenzae.In some embodiments, the anti-CD33 antibodies of the present disclosure can be used in an individual in need thereof to induce or promote the survival, maturation, function, migration, or proliferation of one or more immune cells, or to decrease the activity, function, or survival of regulatory T cells, tumor-buried immunosuppressive dendritic cells, tumor-buried immunosuppressive macrophages, myeloid-derived suppressor cells, tumor-associated macrophages, acute myeloid leukemia (AML) cells, chronic lymphocytic leukemia (CLL) cells, and / or chronic myeloid leukemia (CML) cells. In some embodiments, the anti-CD33 antibodies of the present disclosure are monoclonal antibodies.

[0139] In some embodiments, isolated anti-CD33 antibodies of the present disclosure reduce cellular levels of CD33 (e.g., cell surface levels, intracellular levels, and / or total levels). In some embodiments, isolated anti-CD33 antibodies of the present disclosure induce downregulation of CD33. In some embodiments, isolated anti-CD33 antibodies of the present disclosure induce cleavage of CD33. In some embodiments, isolated anti-CD33 antibodies of the present disclosure induce internalization of CD33. In some embodiments, isolated anti-CD33 antibodies of the present disclosure induce shedding of CD33. In some embodiments, isolated anti-CD33 antibodies of the present disclosure induce degradation of CD33. In some embodiments, isolated anti-CD33 antibodies of the present disclosure induce desensitization of CD33. In some embodiments, isolated anti-CD33 antibodies of the present disclosure act as ligand mimics that transiently activate CD33. In some embodiments, an isolated anti-CD33 antibody of the present disclosure acts as a ligand mimic, temporarily activating CD33 before inducing a reduction in cellular levels of CD33 and / or inhibiting an interaction (e.g., binding) between CD33 and one or more CD33 ligands. In some embodiments, an isolated anti-CD33 antibody of the present disclosure acts as a ligand mimic, temporarily activating CD33 before inducing CD33 degradation. In some embodiments, an isolated anti-CD33 antibody of the present disclosure acts as a ligand mimic, temporarily activating CD33 before inducing CD33 cleavage. In some embodiments, an isolated anti-CD33 antibody of the present disclosure acts as a ligand mimic, temporarily activating CD33 before inducing CD33 internalization. In some embodiments, an isolated anti-CD33 antibody of the present disclosure acts as a ligand mimic, temporarily activating CD33 before inducing CD33 shedding. In some embodiments, an isolated anti-CD33 antibody of the present disclosure acts as a ligand mimic, temporarily activating CD33 before inducing downregulation of CD33 expression. In some embodiments, the isolated anti-CD33 antibodies of the present disclosure act as ligand mimetics, transiently activating CD33 before inducing desensitization of CD33.

[0140] In some embodiments, the isolated anti-CD33 antibodies of the present disclosure are human, humanized, bispecific, monoclonal, multivalent, or chimeric antibodies. Exemplary descriptions of such antibodies are found throughout this disclosure.

[0141] In some embodiments, the anti-CD33 antibodies of the present disclosure bind to human CD33 or homologs thereof, including, without limitation, mammalian CD33 proteins. In some embodiments, the anti-CD33 antibodies of the present disclosure specifically bind to human CD33. In some embodiments, the anti-CD33 antibodies of the present disclosure bind to human CD33 and do not cross-react with CD33 orthologs or homologs from other species.

[0142] In some embodiments, an anti-CD33 antibody of the present disclosure binds to a CD33 protein of the present disclosure expressed on the cell surface and modulates (e.g., induces or inhibits) one or more CD33 activities of the present disclosure after binding to the surface-expressed CD33 protein. In some embodiments, an anti-CD33 antibody of the present disclosure is an inactive antibody.

[0143] Anti-CD33 antibody binding region In some embodiments, the anti-CD33 antibodies of the present disclosure may bind to a conformational epitope. In some embodiments, the anti-CD33 antibodies of the present disclosure may bind to a discontinuous CD33 epitope. In some embodiments, the discontinuous CD33 epitope comprises two or more peptides, three or more peptides, four or more peptides, five or more peptides, six or more peptides, seven or more peptides, eight or more peptides, nine or more peptides, or ten or more peptides. In some embodiments, the anti-CD33 antibodies of the present disclosure may bind to a CD33 epitope comprising one or more peptides. As disclosed herein, a CD33 epitope can comprise one or more peptides comprising 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, 19 or more, or 20 or more amino acid residues of the amino acid sequence of SEQ ID NO:1, or 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, 19 or more, or 20 or more amino acid residues of a mammalian CD33 protein corresponding to the amino acid sequence of SEQ ID NO:1.

[0144] In some embodiments, an anti-CD33 antibody of the disclosure binds to an epitope of human CD33 that is the same as or overlaps with a CD33 epitope bound by an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 103 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 104. In some embodiments, an anti-CD33 antibody of the disclosure binds to essentially the same CD33 epitope as that bound by an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 103 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 104.

[0145] In some embodiments, an anti-CD33 antibody of the disclosure competitively inhibits binding of an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 103 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 104. In some embodiments, an anti-CD33 antibody of the disclosure competes for binding to CD33 with an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 103 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 104.

[0146] In some embodiments, an anti-CD33 antibody of the present disclosure competitively inhibits the binding of at least one antibody selected from any of the antibodies listed in Tables 3A-3C, 4A-4C, 5A-5D, 6A-6D, 7, and 8. In some embodiments, the anti-CD33 antibodies of the disclosure are AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB .5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, AB-64.1.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, AB-H66, and any combination thereof. In some embodiments, the anti-CD33 antibodies of the disclosure exhibit a greater than 100% binding of AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-63.19, AB-63.19, AB-63.20, AB-63.21, AB-63.22, AB-63.23, AB-63.24, AB-63.25, AB-63.26, AB-63.27, AB-63.28, AB-63.29, AB-63.30, AB-63.31, AB-63.32, AB-63.33, AB-63.34, AB-63.35, AB-63.36, AB-63.37, AB-63.38, AB-63.39, AB-63.40, AB-63.41, AB-63.42, AB-63.43, AB-63.44, AB-63.45, AB-63.46, AB-63. .5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63 .15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB- 64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, AB-64.1.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, or the like, when the antibody reduces the binding to CD33 of one or more antibodies selected from AB-H65, AB-H66, and any combination thereof by an amount ranging from about 50% to 100%. , AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64 .2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB -64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, AB-64.1.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, AB-H66, and any combination thereof. In some embodiments, the anti-CD33 antibodies of the disclosure have a binding activity similar to that of AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64. 1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-6 and / or AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, AB-64.1.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, AB-H66, and any combination thereof, to CD33 by at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, A B-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, A B-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, AB-64.1.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, AB-H66, and any combination thereof. In some embodiments, AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1. 4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, AB-6 4.1.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, AB-H66, and any combination thereof, the anti-CD33 antibody of the present disclosure is selected from the group consisting of AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-14.12, AB-14.13, AB-14.14, AB-14.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, AB-H66, and any combination thereof, and , AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16 , AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.and AB-H63, AB-H64, AB-H65, AB-H66, and any combination thereof. In some embodiments, the anti-CD33 antibodies as well as AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB- 64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB- 64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, AB-64.1.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, AB-H66, and any combination thereof. The above antibodies are AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB -14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, A. and an anti-CD33 antibody to one or more antibodies selected from B-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, AB-64.1.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, AB-H66, and any combination thereof in a 10:1 ratio, 9:1 ratio, 8:1 ratio, 7:1 ratio, 6:1 ratio, 5:1 ratio, 4:1 ratio, 3:1 ratio, 2:1 ratio, 1:1 ratio, 0.75:1 ratio, 0.5:1 ratio, 0.25:1 ratio, 0.1:1 ratio, 0.075:1 ratio, 0.050:1 ratio, 0.025:1 ratio, 0.01:1 ratio, 0.0075 ... ratio, 0.0050:1 ratio, 0.0025:1 ratio, 0.001: ratio, 0.00075:1 ratio, 0.00050:1 ratio, 0.00025:1 ratio, 0.0001 : ratio, 1:10 ratio, 1:9 ratio, 1:8 ratio, 1:7 ratio, 1:6 ratio, 1:5 ratio, 1:4 ratio, 1:3 ratio, 1:2 ratio, 1:0.75 ratio, 1:0.5 ratio, 1:0.25 The compound is present in an amount corresponding to a ratio of 1:0.1, 1:0.075, 1:0.050, 1:0.025, 1:0.01, 1:0.0075, 1:0.0050, 1:0.0025, 1:0.001, 1:0.00075, 1:0.00050, 1:0.00025, or 1:0.0001.In some embodiments, the anti-CD33 antibody is AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB -63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63 .16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-6 and AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, AB-64.1.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, AB-H66, and any combination thereof.In some embodiments, the anti-CD33 antibody is AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63. 10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1 .3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.1 1, AB-64.1.12, AB-64.1.13, AB-64.1.14, AB-64.1.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H 64, AB-H65, AB-H66, and any combination thereof, and in an amount of about 2x, 3x, 4x, 5x, 6x, 7x, 8x, 9x, 10x, 15x, 20x, 25x, 30x, 35x, 40x, 45x, 50x, 55x, 60x, 65x, 70x, 75x, 80x, 85x, 90x, 95x, or 100x excess relative to the amount of one or more antibodies selected from AB-H64, AB-H65, AB-H66, and any combination thereof.

[0147] In some embodiments, an anti-CD33 antibody of the disclosure binds to a human CD33 epitope that is the same as or overlaps with a CD33 epitope bound by at least one antibody selected from any of the antibodies set forth in Tables 3A-3C, 4A-4C, 5A-5D, 6A-6D, 7, and 8. In some embodiments, an anti-CD33 antibody of the disclosure is selected from AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-14.10, AB-14.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-63.19, AB-63.20, AB-63.21, AB-63.22, AB-63.23, AB-63.24, AB-63.25, AB-63.26, AB-63.27, AB-63.28, AB-63.29, AB-63.30, AB-63.31, AB-63.32, AB-63.33, AB-63.34, AB-63.35, AB-63.36, AB-63.37, AB-63.38, AB 7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, A B-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6 , AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, AB-64.1.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, AB-H66.

[0148] In some embodiments, the anti-CD33 antibodies of the present disclosure bind to essentially the same CD33 epitope as that bound by at least one antibody selected from any of the antibodies set forth in Tables 3A-3C, 4A-4C, 5A-5D, 6A-6D, 7, and 8. In some embodiments, the anti-CD33 antibodies of the disclosure are AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5 , AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, AB-64.1.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, AB-H66. Details of exemplary methods for mapping antibody-binding epitopes are provided in Morris (1996) "Epitope Mapping Protocols," in Methods in Molecular Biology, vol. 66 (Humana Press, Totowa, NJ).

[0149] In some embodiments, the anti-CD33 antibodies of the disclosure are AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB and any combination thereof.

[0150]

[00130] Using any suitable competition or CD33 binding assay known in the art, e.g., BIAcore analysis, ELISA assay, or flow cytometry, the anti-CD33 antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3 .2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1. 3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1 The assay can determine whether a hybridoma competes for binding to CD33 with one or more antibodies selected from AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, AB-64.1.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, AB-H66, and any combination thereof. In an exemplary competition assay, immobilized CD33 or cells expressing CD33 on their cell surface are incubated in a solution containing a primary labeled antibody that binds to CD33 (e.g., human or non-human primate) and a secondary unlabeled antibody to be tested for its ability to compete with the primary antibody for binding to CD33. The secondary antibody can be present in hybridoma supernatant. As a control, immobilized CD33 or cells expressing CD33 are incubated in a solution containing the primary labeled antibody but not the secondary unlabeled antibody. After incubation under conditions that allow binding of the primary antibody to CD33, excess unbound antibody is removed and the amount of label associated with immobilized CD33 or cells expressing CD33 is measured.A substantial decrease in the amount of label associated with immobilized CD33 or cells expressing CD33 in the test sample relative to the control sample indicates that the secondary antibody competes with the primary antibody for binding to CD33. See Harlow and Lane (1988) Antibodies: A Laboratory Manual, ch. 14 (Cold Spring Harbor Laboratory, Cold Spring Harbor, NY).

[0151] Light and heavy chain variable regions of anti-CD33 antibodies In some embodiments, an anti-CD33 antibody of the disclosure comprises a heavy chain variable region comprising one or more (e.g., one or more, two or more, or all three) HVRs selected from HVR-H1, HVR-H2, and HVR-H3 (as set forth in Tables 3A-3C). In some embodiments, the heavy chain variable region comprises HVR-H1, HVR-H2, and HVR-H3 (as set forth in Tables 3A-3C). In some embodiments, the antibody is not an antibody comprising a heavy chain variable region comprising HVR-H1 comprising the sequence of GYTFTDYNLH (SEQ ID NO: 105), HVR-H2 comprising the sequence of FIYPSNGITG (SEQ ID NO: 115), and HVR-H3 comprising the sequence of STVDYFDY (SEQ ID NO: 121).

[0152] In some embodiments, the HVR-H1 comprises a sequence of Formula I: GX1X2X3TDYNX4H (SEQ ID NO: 152), where Xi is Y, A, or V, X2 is T or A, X3 is F, E, or H, and X4 is L, F, Y, or N. In some embodiments, the HVR-H1 comprises a sequence selected from SEQ ID NOs: 105-114. In some embodiments, the HVR-H2 comprises a sequence of Formula II: FIYPX1NX2IX3G (SEQ ID NO: 153), where Xi is S or A, X2 is G, Q, R, or V, and X3 is T or R. In some embodiments, the HVR-H2 comprises a sequence selected from SEQ ID NOs: 115-120. In some embodiments, the HVR-H3 comprises a sequence of Formula III:SX1VDYFDX2 (SEQ ID NO: 154), where X1 is T, D, F, or S and X2 is Y, D, or L. In some embodiments, the HVR-H3 comprises a sequence selected from SEQ ID NOs: 121-126.

[0153] In some embodiments, the heavy chain variable region comprises HVR-H1 of Formula I, HVR-H2 of Formula II, and HVR-H3 of Formula III, and the antibody is not an antibody comprising a heavy chain variable region comprising HVR-H1 comprising the sequence of GYTFTDYNLH (SEQ ID NO: 105), HVR-H2 comprising the sequence of FIYPSNGITG (SEQ ID NO: 115), and HVR-H3 comprising the sequence of STVDYFDY (SEQ ID NO: 121). In some embodiments, the heavy chain variable region comprises HVR-H1 comprising a sequence selected from SEQ ID NOs: 105 to 114, HVR-H2 comprising a sequence selected from SEQ ID NOs: 115 to 120, and HVR-H3 comprising a sequence selected from SEQ ID NOs: 121 to 126, and the antibody is not an antibody comprising a heavy chain variable region comprising HVR-H1 comprising the sequence GYTFTDYNLH (SEQ ID NO: 105), HVR-H2 comprising the sequence FIYPSNGITG (SEQ ID NO: 115), and HVR-H3 comprising the sequence STVDYFDY (SEQ ID NO: 121).

[0154] In some embodiments, the heavy chain variable region is selected from the group consisting of antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-6 ...64.9, AB-14.10, AB-14.11, AB-63.12, AB-63 .4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15, and any combination thereof of HVR-H1, HVR-H2, and HVR-H3 (as shown in Tables 3A-3C).

[0155] In some embodiments, an anti-CD33 antibody of the disclosure comprises a heavy chain variable region selected from the group consisting of: (a) antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB- HVR-H1 amino of 64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 (b) antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, and AB-14.9; and (c) antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, and AB-14.9. , AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-6 3.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, or at least 90% identical to the HVR-H2 amino acid sequence of AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 and (c) antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-14.12, AB-14.13, AB-14.14, AB-14.15, AB-14.16, AB-14.17, AB-14.18, AB-14.19, AB-14.20, AB-14.21, AB-14.22, AB-14.23, AB-14.24, AB-14.25, AB-14.26, AB-14.27, AB-14.28, AB-14.29 ...9, AB-14.20, AB-14.21, AB AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, A B-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB -64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.The antibody comprises one or more HVR-H3s comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the HVR-H3 amino acid sequences of 15, and the antibody is not an antibody comprising a heavy chain variable region comprising HVR-H1 comprising the sequence of GYTFTDYNLH (SEQ ID NO: 105), HVR-H2 comprising the sequence of FIYPSNGITG (SEQ ID NO: 115), and HVR-H3 comprising the sequence of STVDYFDY (SEQ ID NO: 121).

[0156] In some embodiments, an anti-CD33 antibody of the disclosure comprises an HVR-H1 comprising the amino acid sequence GYTFTDYNLH (SEQ ID NO: 105), an HVR-H2 comprising the amino acid sequence FIYPSNRITG (SEQ ID NO: 119), and an HVR-H3 comprising the amino acid sequence SDVDYFDY (SEQ ID NO: 122). In some embodiments, an anti-CD33 antibody of the disclosure comprises an HVR-H1 comprising the amino acid sequence GYTFTDYNLH (SEQ ID NO: 105), an HVR-H2 comprising the amino acid sequence FIYPSNQITG (SEQ ID NO: 118), and an HVR-H3 comprising the amino acid sequence SDVDYFDY (SEQ ID NO: 122).

[0157] In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable region comprising one or more (e.g., one or more, two or more, or all three) HVRs selected from HVR-L1, HVR-L2, and HVR-L3 (as set forth in Tables 4A-4C). In some embodiments, the light chain variable region comprises HVR-L1, HVR-L2, and HVR-L3 (as set forth in Tables 4A-4C). In some embodiments, the antibody is not an antibody comprising a light chain variable region comprising HVR-L1 comprising the sequence of RASQSVSTSTYSYMH (SEQ ID NO: 127), HVR-L2 comprising the sequence of YASNLES (SEQ ID NO: 135), and HVR-L3 comprising the sequence of QHSWEIPLT (SEQ ID NO: 146).

[0158] In some embodiments, the HVR-L1 comprises a sequence of formula IV: X1X2SQX3VX4X5STYSYMH (SEQ ID NO: 155), where X1 is R or K, X2 is A, G, or V, X3 is S or D, X4 is S, G, or H, and X5 is T or A. In some embodiments, the HVR-L1 comprises a sequence selected from SEQ ID NOs: 127-134. In some embodiments, the HVR-L2 comprises a sequence of formula V: YX1X2X3X4X5S (SEQ ID NO: 156), where X1 is A, V, or E, X2 is S, V, or F, X3 is N, A, Y, or F, X4 is L or V, and X5 is E, G, or N. In some embodiments, the HVR-L2 comprises a sequence selected from SEQ ID NOs: 135-145. In some embodiments, the HVR-L3 comprises a sequence of formula VI: X1HSX2X3X4PLX5 (SEQ ID NO: 157), where X1 is Q or E, X2 is W or E, X3 is E or A, X4 is I or L, and X5 is T or E. In some embodiments, the HVR-l3 comprises a sequence selected from SEQ ID NOs: 146-151.

[0159] In some embodiments, the light chain variable region comprises HVR-L1 of Formula IV, HVR-L2 of Formula V, and HVR-L3 of Formula VI, and the antibody is not an antibody comprising a light chain variable region comprising HVR-L1 comprising the sequence of RASQSVSTSTYSYMH (SEQ ID NO: 127), HVR-L2 comprising the sequence of YASNLES (SEQ ID NO: 135), and HVR-L3 comprising the sequence of QHSWEIPLT (SEQ ID NO: 146). In some embodiments, the light chain variable region comprises HVR-L1 comprising a sequence selected from SEQ ID NOs: 127 to 134, HVR-L2 comprising a sequence selected from SEQ ID NOs: 135 to 145, and HVR-L3 comprising a sequence selected from SEQ ID NOs: 146 to 151, and the antibody is not an antibody comprising a light chain variable region comprising HVR-L1 comprising a sequence of RASQSVSTSTYSYMH (SEQ ID NO: 127), HVR-L2 comprising a sequence of YASNLES (SEQ ID NO: 135), and HVR-L3 comprising a sequence of QHSWEIPLT (SEQ ID NO: 146).

[0160] In some embodiments, the light chain variable region comprises the HVR-L1, HVR-L2, and HVR-L3 of antibody AB-14.3, AB-14.4, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, or AB-64.8, and any combination thereof (as shown in Tables 4A-4C).

[0161] In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable region, the light chain variable region being selected from the group consisting of: (a) antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB- HVR-L1 amino of 64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 (b) antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, and AB-14.9; and (c) antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, and AB-14.9. , AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-6 3.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.or AB-64.1.15, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15. and (c) an HVR-L2 comprising an amino acid sequence with at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, A B-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB -64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.The antibody comprises one or more HVR-L3s comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the HVR-L3 amino acid sequence of SEQ ID NO: 15, and the antibody is not an antibody comprising a light chain variable region comprising an HVR-L1 comprising the sequence RASQSVSTSTYSYMH (SEQ ID NO: 127), an HVR-L2 comprising the sequence YASNLES (SEQ ID NO: 135), and an HVR-L3 comprising the sequence QHSWEIPLT (SEQ ID NO: 146).

[0162] In some embodiments, an anti-CD33 antibody of the disclosure comprises an HVR-L1 comprising the amino acid sequence RASQSVSTSTYSYMH (SEQ ID NO: 127), an HVR-L2 comprising the amino acid sequence YASNLES (SEQ ID NO: 135), and an HVR-L3 comprising the amino acid sequence QHSWEIPLT (SEQ ID NO: 146). In some embodiments, an anti-CD33 antibody of the disclosure comprises an HVR-L1 comprising the amino acid sequence RASQSVSTSTYSYMH (SEQ ID NO: 127), an HVR-L2 comprising the amino acid sequence YASNLES (SEQ ID NO: 135), and an HVR-L3 comprising the amino acid sequence QHSWEIPLT (SEQ ID NO: 146).

[0163] In some embodiments, an anti-CD33 antibody of the disclosure comprises a heavy chain variable region comprising one or more (e.g., one or more, two or more, or all three) HVRs selected from HVR-H1, HVR-H2, and HVR-H3 (as shown in Tables 3A-3C), and a light chain variable region comprising one or more (e.g., one or more, two or more, or all three) HVRs selected from HVR-L1, HVR-L2, and HVR-L3 (as shown in Tables 4A-4C). In some embodiments, the heavy chain variable region comprises HVR-H1, HVR-H2, and HVR-H3 (as shown in Tables 3A-3C), and the light chain variable region comprises HVR-L1, HVR-L2, and HVR-L3 (as shown in Tables 4A-4C). In some embodiments, the antibody is not an antibody comprising a heavy chain variable region comprising HVR-H1 comprising the sequence GYTFTDYNLH (SEQ ID NO: 105), HVR-H2 comprising the sequence FIYPSNGITG (SEQ ID NO: 115), and HVR-H3 comprising the sequence STVDYFDY (SEQ ID NO: 121), and a light chain variable region comprising HVR-L1 comprising the sequence RASQSVSTSTYSYMH (SEQ ID NO: 127), HVR-L2 comprising the sequence YASNLES (SEQ ID NO: 135), and HVR-L3 comprising the sequence QHSWEIPLT (SEQ ID NO: 146).

[0164] In some embodiments, the heavy chain variable region comprises HVR-H1 of Formula I, HVR-H2 of Formula II, and HVR-H3 of Formula III; the light chain variable region comprises HVR-L1 of Formula IV, HVR-L2 of Formula V, and HVR-L3 of Formula VI; and the antibody is not an antibody comprising a heavy chain variable region comprising HVR-H1 comprising the sequence of GYTFTDYNLH (SEQ ID NO: 105), HVR-H2 comprising the sequence of FIYPSNGITG (SEQ ID NO: 115), and HVR-H3 comprising the sequence of STVDYFDY (SEQ ID NO: 121), and a light chain variable region comprising HVR-L1 comprising the sequence of RASQSVSTSTYSYMH (SEQ ID NO: 127), HVR-L2 comprising the sequence of YASNLES (SEQ ID NO: 135), and HVR-L3 comprising the sequence of QHSWEIPLT (SEQ ID NO: 146). In some embodiments, the heavy chain variable region comprises HVR-H1 comprising a sequence selected from SEQ ID NOs: 105 to 114, HVR-H2 comprising a sequence selected from SEQ ID NOs: 115 to 120, and HVR-H3 comprising a sequence selected from SEQ ID NOs: 121 to 126; the light chain variable region comprises HVR-L1 comprising a sequence selected from SEQ ID NOs: 127 to 134, HVR-L2 comprising a sequence selected from SEQ ID NOs: 135 to 145, and HVR-L3 comprising a sequence selected from SEQ ID NOs: 146 to 151; and the antibody is not an antibody comprising a heavy chain variable region comprising HVR-H1 comprising the sequence GYTFTDYNLH (SEQ ID NO: 105), HVR-H2 comprising the sequence FIYPSNGITG (SEQ ID NO: 115), and HVR-H3 comprising the sequence STVDYFDY (SEQ ID NO: 121), and a light chain variable region comprising HVR-L1 comprising the sequence RASQSVSTSTYSYMH (SEQ ID NO: 127), HVR-L2 comprising the sequence YASNLES (SEQ ID NO: 135), and HVR-L3 comprising the sequence QHSWEIPLT (SEQ ID NO: 146).

[0165] In some embodiments, the anti-CD33 antibodies of the disclosure are antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63. 15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-6 4.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB- and antibodies AB-14.3, AB-14.4, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15, and any combination thereof, including heavy chain variable regions comprising HVR-H1, HVR-H2, and HVR-H3 (as shown in Tables 3A-3C). and a light chain variable region comprising HVR-L1, HVR-L2, and HVR-L3 (as shown in Tables 4A-4C) of AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, or AB-64.8, and any combination thereof.In some embodiments, an anti-CD33 antibody of the disclosure comprises a heavy chain variable region comprising HVR-H1, HVR-H2, and HVR-H3 and a light chain variable region comprising HVR-L1, HVR-L2, and HVR-L3, and is selected from the group consisting of antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-63.19, AB-63.20, AB-63.21, AB-63.22, AB-63.23, AB-63.24, AB-63.25, AB-63.26, AB-63.27, AB-63.28, AB-63.29, AB-63.30, AB-63.31, AB-63.32, AB-63.33, AB-63.34, AB-63.35, AB-63.36, AB-63.37, AB-63.38, AB-63.39, AB-63.40, AB-63.41, AB-63.42, AB -63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-6 4.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB- 64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 (as shown in Tables 3A-3C and 4A-4C), including HVR-H1, HVR-H2, HVR-H3, HVR-L1, HVR-L2, and HVR-L3.

[0166] In some embodiments, an anti-CD33 antibody of the disclosure comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region is selected from the group consisting of: (a) antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-6 4.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15. (b) antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-14.12, AB-14.13, AB-14.14, AB-14.15, AB-14.16, AB-14.17, AB-14.18, AB-14.19, AB-14.20, AB-14.21, AB-14.22, AB-14.23, AB-14.24, AB-14.25, AB-14.26, AB-14.27, AB-14.28, AB-14.29, AB-14.30, AB-14.31, AB-14.32, AB-14.33, AB-14.34, AB-14.35, AB-14.36, AB-14.37, AB-14.38, AB-14.39, AB-14.40, AB-14.41, AB-14.42, AB-14.43, AB-14.44, AB-14.45, AB-14.46, AB-14.47, AB-14.48, AB-14.49, AB-14.50, AB-14.51, AB-14.52, AB-14.53, AB-14.54, AB-14.55, AB-14.56, AB-14.57, AB- .8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB- 63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 100%, at least 101%, at least 102%, at least 103%, at least 104%, at least 105%, at least 106%, at least 107%, at least 108%, at least 109%, at least 1109%, at least 1111%, at least 1120%, at least 1130%, at least 1140%, at least 1151%, at least 1160%, at least 1170%, at least 1180%, at least 1190%, at least 1191, at least 1192, at least 1193, at least 1194, at least 1195, at least 1196, at least 1201, at least 1211, at least 1212, at least 1213, at least 1214, at least 1215, at least 1216, at least 1217, at least 1218, at least 1221, at least 1222, at least 1231, at least 1232, at least 1233, at least 1234, at least 1235, at least 1236, at least 1237, at least 1238, at least 1239, at least 1241, at least 1242, at least 1243, at least 1244, at least 1245, at least 1246, at least 1247, at least 1248 and (c) an HVR-H2 comprising an amino acid sequence with 9%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB- 14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.1 1, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64. 4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, A B-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.and one or more HVR-H3s comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the 15 HVR-H3 amino acid sequences, and the antibody includes an HVR-H1 comprising the sequence of GYTFTDYNLH (SEQ ID NO: 105), FIYPSNGITG (SEQ ID NO: 11), or a HVR-H2 comprising the sequence of GYTFTDYNLH (SEQ ID NO: 11). 5), and HVR-H3 comprising the sequence of STVDYFDY (SEQ ID NO: 121), and the light chain variable region is not an antibody comprising a heavy chain variable region comprising HVR-H2 comprising the sequence of STVDYFDY (SEQ ID NO: 121), but the light chain variable region is (a) antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63 .13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, A B-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, A (b) antibodies B-14.1, AB-14.2, AB-14.3, AB-14.4, and AB-14.5; and (c) antibodies B-14.1, AB-14.2, AB-14.3, AB-14.4, and AB-14.6; and (d) antibodies B-14.1, AB-14.2, AB-14.3, AB-14.4, and AB-14.7; and (e) antibodies B-14.1, AB-14.2, AB-14.3, AB-14.4, and AB-14.8; and (f) antibodies B-14.1, AB-14.2, AB-14.3, AB-14.4, and AB-14.9; and (f) antibodies B-14.1, AB-14.5, AB-14.6, AB-14.7, AB-14.9, and AB-14.9; and (f) antibodies B-14.1, AB-14.2, AB-14.3, AB-14.4, and AB-14.9; and (f) antibodies B-14.1, AB-14.5, AB-14.6, AB-14.7, AB-14.9, AB-14.9, AB-14.9, AB-14.10, AB-14.11, AB-14.12, AB-14.13, AB-14.14, AB-14.15, and AB-14.16; and (f) antibodies B-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-145, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63. 12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-6 at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 100%, at least 101%, at least 102%, at least 103%, at least 104%, at least 105%, at least 106%, at least 107%, at least 108%, at least 109%, at least 1109%, at least 1111, at least 112, at least 113, at least 114, at least 115, at least 116%, at least 117%, at least 118%, at least 119%, at least 1200, at least 1210, at least 1220, at least 1230, at least 1240, at least 1250, at least 1260, at least 1270, at least 1280, at least 1290, at least 1300, at least 1310, at least 1320, at least 1330, at least 1340, at least 1350, at least 1360, at least 1370, at least 1380, at least 1390, at least 1400, at least 1410, at least 1420, at least 1430, at least 1440, at least 1450, at least 1460, at least 1470, at least 1480, at least 1490, at least 1490, at least 1490, at least 1490, at least 1490, at least 1490 and (c) an HVR-L2 comprising an amino acid sequence with 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, and AB-63. 11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB- 64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.and one or more HVR-L3s comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the HVR-L3 amino acid sequence of AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15, wherein the antibody is not an antibody comprising a light chain variable region comprising an HVR-L1 comprising the sequence of RASQSVSTSTYSYMH (SEQ ID NO: 127), an HVR-L2 comprising the sequence of YASNLES (SEQ ID NO: 135), and an HVR-L3 comprising the sequence of QHSWEIPLT (SEQ ID NO: 146).

[0167] In some embodiments, an anti-CD33 antibody of the present disclosure comprises an HVR-H1 comprising the amino acid sequence GYTFTDYNLH (SEQ ID NO: 105), an HVR-H2 comprising the amino acid sequence FIYPSNRITG (SEQ ID NO: 119), an HVR-H3 comprising the amino acid sequence SDVDYFDY (SEQ ID NO: 122), an HVR-L1 comprising the amino acid sequence RASQSVSTSTYSYMH (SEQ ID NO: 127), an HVR-L2 comprising the amino acid sequence YASNLES (SEQ ID NO: 135), and an HVR-L3 comprising the amino acid sequence QHSWEIPLT (SEQ ID NO: 146). In some embodiments, an anti-CD33 antibody of the disclosure comprises an HVR-H1 comprising the amino acid sequence GYTFTDYNLH (SEQ ID NO: 105), an HVR-H2 comprising the amino acid sequence FIYPSNQITG (SEQ ID NO: 118), an HVR-H3 comprising the amino acid sequence SDVDYFDY (SEQ ID NO: 122), an HVR-L1 comprising the amino acid sequence RASQSVSTSTYSYMH (SEQ ID NO: 127), an HVR-L2 comprising the amino acid sequence YASNLES (SEQ ID NO: 135), and an HVR-L3 comprising the amino acid sequence QHSWEIPLT (SEQ ID NO: 146).

[0168] In some embodiments, an anti-CD33 antibody of the present disclosure comprises a heavy chain variable region comprising an amino acid sequence selected from SEQ ID NOs: 34 to 72. In some embodiments, the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 59. In some embodiments, the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 65. In some embodiments, the anti-CD33 antibodies of the disclosure include antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-63.19, AB-63.20, AB-63.21, AB-63.22, AB-63.23, AB-63.24, AB-63.25, AB-63.26, AB-63.27, AB-63.28, AB-63.29, AB-63.30, AB-63.31, AB-63.32, AB-63.33, AB-63.34, AB-63.35, AB-63.36, AB-63.37, AB-63.38, AB-63.39, AB-63.40, AB-63.41, AB-63.42, AB-63.43, AB-63.44, AB-63.45, AB-63.46, AB-63.47, AB-63.48, AB-63. AB-64.1.8, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 (as shown in Table 7). In some embodiments, an anti-CD33 antibody of the disclosure comprises a heavy chain variable region comprising HVR-H1 comprising the amino acid sequence GYTFTDYNLH (SEQ ID NO: 105), HVR-H2 comprising the amino acid sequence FIYPSNRITG (SEQ ID NO: 119), and HVR-H3 comprising the amino acid sequence SDVDYFDY (SEQ ID NO: 122). In some embodiments, an anti-CD33 antibody of the disclosure comprises a heavy chain variable region comprising HVR-H1 comprising the amino acid sequence GYTFTDYNLH (SEQ ID NO: 105), HVR-H2 comprising the amino acid sequence FIYPSNQITG (SEQ ID NO: 118), and HVR-H3 comprising the amino acid sequence SDVDYFDY (SEQ ID NO: 122).

[0169] In some embodiments, an anti-CD33 antibody of the present disclosure comprises a light chain variable region comprising an amino acid sequence selected from SEQ ID NOs: 77 to 101. In some embodiments, the light chain variable region comprises the amino acid sequence of SEQ ID NO: 86. In some embodiments, the anti-CD33 antibodies of the disclosure include antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-63.19, AB-63.20, AB-63.21, AB-63.22, AB-63.23, AB-63.24, AB-63.25, AB-63.26, AB-63.27, AB-63.28, AB-63.29, AB-63.30, AB-63.31, AB-63.32, AB-63.33, AB-63.34, AB-63.35, AB-63.36, AB-63.37, AB-63.38, AB-63.39, AB-63.40, AB-63.41, AB-63.42, AB-63.43, AB-63.44, AB-63.45, AB-63.46, AB-63.47, AB-63.48, AB-63. AB-64.1.8, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 (as shown in Table 8). In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable region comprising HVR-L1 comprising the amino acid sequence RASQSVSTSTYSYMH (SEQ ID NO: 127), HVR-L2 comprising the amino acid sequence YASNLES (SEQ ID NO: 135), and HVR-L3 comprising the amino acid sequence QHSWEIPLT (SEQ ID NO: 146). In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable region comprising HVR-L1 comprising the amino acid sequence RASQSVSTSTYSYMH (SEQ ID NO: 127), HVR-L2 comprising the amino acid sequence YASNLES (SEQ ID NO: 135), and HVR-L3 comprising the amino acid sequence QHSWEIPLT (SEQ ID NO: 146).

[0170] In some embodiments, an anti-CD33 antibody of the present disclosure comprises a heavy chain variable region comprising an amino acid sequence selected from SEQ ID NOs: 34 to 72, and a light chain variable region comprising an amino acid sequence selected from SEQ ID NOs: 77 to 101. In some embodiments, the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 59, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 86. In some embodiments, the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 65, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 86.In some embodiments, the anti-CD33 antibodies of the disclosure include antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, the heavy chain variable region of AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 (as shown in Table 7 ), and antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-63.19, AB-64.20, AB-64.21, AB-64.22, AB-64.23, AB-64.24, AB-64.25, AB-64.26, AB-64.27, AB-64.28, AB-64.29, AB-65.30, AB-65.31, AB-65.32, AB-65.33, AB-65.34, AB-65.35, AB-65.36, AB-65.37, AB-65.38, AB-65.39, AB-66.40, AB-66.41, AB-66.42, AB-66.43, AB-66.44, AB-66.45, AB-66.46, AB-66.47, AB-66.48, AB-66.49, AB and / or AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 light chain variable region (as shown in Table 8).In some embodiments, an anti-CD33 antibody of the disclosure comprises a heavy chain variable region comprising HVR-H1 comprising the amino acid sequence GYTFTDYNLH (SEQ ID NO: 105), HVR-H2 comprising the amino acid sequence FIYPSNRITG (SEQ ID NO: 119), HVR-H3 comprising the amino acid sequence SDVDYFDY (SEQ ID NO: 122), and a light chain variable region comprising HVR-L1 comprising the amino acid sequence RASQSVSTSTYSYMH (SEQ ID NO: 127), HVR-L2 comprising the amino acid sequence YASNLES (SEQ ID NO: 135), and HVR-L3 comprising the amino acid sequence QHSWEIPLT (SEQ ID NO: 146). In some embodiments, an anti-CD33 antibody of the disclosure comprises a heavy chain variable region comprising HVR-H1 comprising the amino acid sequence GYTFTDYNLH (SEQ ID NO: 105), HVR-H2 comprising the amino acid sequence FIYPSNQITG (SEQ ID NO: 118), HVR-H3 comprising the amino acid sequence SDVDYFDY (SEQ ID NO: 122), and a light chain variable region comprising HVR-L1 comprising the amino acid sequence RASQSVSTSTYSYMH (SEQ ID NO: 127), HVR-L2 comprising the amino acid sequence YASNLES (SEQ ID NO: 135), and HVR-L3 comprising the amino acid sequence QHSWEIPLT (SEQ ID NO: 146).

[0171] In some embodiments, an anti-CD33 antibody of the disclosure comprises a heavy chain variable region comprising an amino acid sequence selected from SEQ ID NOs: 34, 40, 42, 52, 53, and 73-76. In some embodiments, the antibody comprises the heavy chain variable region of AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, or AB-H66 (as shown in Table 7). In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable region comprising an amino acid sequence selected from SEQ ID NOs: 77, 86, and 102. In some embodiments, the antibody comprises the light chain variable region of antibody AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, or AB-H66 (as shown in Table 8). In some embodiments, an anti-CD33 antibody of the disclosure comprises a heavy chain variable region comprising an amino acid sequence selected from SEQ ID NOs: 34, 40, 42, 52, 53, and 73-76, and a light chain variable region comprising an amino acid sequence selected from SEQ ID NOs: 77, 86, and 102. In some embodiments, the antibody comprises the heavy chain variable region of antibody AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, or AB-H66 (as shown in Table 7), and the light chain variable region of antibody AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, or AB-H66 (as shown in Table 8).

[0172] Any of the antibodies of the present disclosure can be produced by a cell line. In some embodiments, the cell line can be a mammalian cell line. In certain embodiments, the cell line can be a hybridoma cell line. In other embodiments, the cell line can be a yeast cell line. Any cell line known in the art that is suitable for antibody production can be used to produce the antibodies of the present disclosure. Exemplary cell lines for antibody production are described throughout this disclosure.

[0173] In some embodiments, the anti-CD33 antibody is AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64. AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, AB-64.1.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, or AB-H66.

[0174] In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain and a heavy chain variable domain, wherein the heavy chain variable domain has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1 or the amino acid sequence of SEQ ID NO: 52. and / or the light chain variable domain comprises an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1 or the amino acid sequence of SEQ ID NO:86. In some embodiments, an anti-CD33 antibody of the present disclosure comprises a heavy chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1 or the amino acid sequence of SEQ ID NO: 52, wherein the heavy chain variable domain comprises the amino acid sequence of HVR-H1, HVR-H2, and HVR-H3 of antibody AB-64.1.In some embodiments, an anti-CD33 antibody of the present disclosure comprises a light chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1 or the amino acid sequence of SEQ ID NO: 86, wherein the light chain variable domain comprises the amino acid sequence of HVR-L1, HVR-L2, and HVR-L3 of antibody AB-64.1. In some embodiments, the anti-CD33 antibody comprises a heavy chain variable domain (VH) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1 or the amino acid sequence of SEQ ID NO: 52, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence), but the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1 or the amino acid sequence of SEQ ID NO: 52. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1 or the amino acid sequence of SEQ ID NO: 52. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VH sequence of antibody CD33 or SEQ ID NO: 52, including post-translational modifications of that sequence.In certain embodiments, the VH comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-H1 of antibody AB-64.1, (b) the amino acid sequence of HVR-H2 of antibody AB-64.1, and (c) the amino acid sequence of HVR-H3 of antibody AB-64.1. In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain (VL) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1 or the amino acid sequence of SEQ ID NO: 86, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence), but the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VL sequence of antibody AB-64.1 or SEQ ID NO: 86, including post-translational modifications of that sequence. In certain embodiments, the VL comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-L1 of antibody AB-64.1, (b) the amino acid sequence of HVR-L2 of antibody AB-64.1, and (c) the amino acid sequence of HVR-L3 of antibody AB-64.1.

[0175] In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain and a heavy chain variable domain, wherein the heavy chain variable domain has an amino acid sequence that is at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.1 or the amino acid sequence of SEQ ID NO:58. and / or the light chain variable domain comprises an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.1 or the amino acid sequence of SEQ ID NO:86. In some embodiments, an anti-CD33 antibody of the present disclosure comprises a heavy chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.1 or the amino acid sequence of SEQ ID NO: 58, wherein the heavy chain variable domain comprises the amino acid sequence of HVR-H1, HVR-H2, and HVR-H3 of antibody AB-64.1.1.In some embodiments, an anti-CD33 antibody of the present disclosure comprises a light chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.1 or the amino acid sequence of SEQ ID NO: 86, and the light chain variable domain comprises the amino acid sequence of HVR-L1, HVR-L2, and HVR-L3 of antibody AB-64.1.1. In some embodiments, the anti-CD33 antibody comprises a heavy chain variable domain (VH) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.1 or the amino acid sequence of SEQ ID NO: 58, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence), but the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.1 or the amino acid sequence of SEQ ID NO: 58. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.1 or the amino acid sequence of SEQ ID NO: 58. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VH sequence of antibody CD33 or SEQ ID NO: 58, including post-translational modifications of that sequence.In certain embodiments, the VH comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-H1 of antibody AB-64.1.1, (b) the amino acid sequence of HVR-H2 of antibody AB-64.1.1, and (c) the amino acid sequence of HVR-H3 of antibody AB-64.1.1. In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain (VL) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.1 or the amino acid sequence of SEQ ID NO: 86, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence) but wherein the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.1 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.1 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VL sequence of antibody AB-64.1.1 or SEQ ID NO: 86, including post-translational modifications of that sequence. In certain embodiments, the VL comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-L1 of antibody AB-64.1.1, (b) the amino acid sequence of HVR-L2 of antibody AB-64.1.1, and (c) the amino acid sequence of HVR-L3 of antibody AB-64.1.1.

[0176] In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain and a heavy chain variable domain, wherein the heavy chain variable domain has an amino acid sequence that is at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.2 or the amino acid sequence of SEQ ID NO:59. and / or the light chain variable domain comprises an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.2 or the amino acid sequence of SEQ ID NO:86. In some embodiments, an anti-CD33 antibody of the present disclosure comprises a heavy chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.2 or the amino acid sequence of SEQ ID NO: 59, wherein the heavy chain variable domain comprises the amino acid sequence of HVR-H1, HVR-H2, and HVR-H3 of antibody AB-64.1.2.In some embodiments, an anti-CD33 antibody of the present disclosure comprises a light chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.2 or the amino acid sequence of SEQ ID NO: 86, wherein the light chain variable domain comprises the amino acid sequence of HVR-L1, HVR-L2, and HVR-L3 of antibody AB-64.1.2. In some embodiments, the anti-CD33 antibody comprises a heavy chain variable domain (VH) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.2 or the amino acid sequence of SEQ ID NO: 59, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence) but wherein the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.2 or the amino acid sequence of SEQ ID NO: 59. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.2 or the amino acid sequence of SEQ ID NO: 59. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VH sequence of antibody CD33 or SEQ ID NO: 59, including post-translational modifications of that sequence.In certain embodiments, the VH comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-H1 of antibody AB-64.1.2, (b) the amino acid sequence of HVR-H2 of antibody AB-64.1.2, and (c) the amino acid sequence of HVR-H3 of antibody AB-64.1.2. In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain (VL) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.2 or the amino acid sequence of SEQ ID NO: 86, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence) but such anti-CD33 antibodies retain the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.2 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.2 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VL sequence of antibody AB-64.1.2 or SEQ ID NO: 86, including post-translational modifications of that sequence. In certain embodiments, the VL comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-L1 of antibody AB-64.1.2, (b) the amino acid sequence of HVR-L2 of antibody AB-64.1.2, and (c) the amino acid sequence of HVR-L3 of antibody AB-64.1.2.

[0177] In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain and a heavy chain variable domain, wherein the heavy chain variable domain has an amino acid sequence that is at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.3 or the amino acid sequence of SEQ ID NO: 60. and / or the light chain variable domain comprises an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.3 or the amino acid sequence of SEQ ID NO:86. In some embodiments, an anti-CD33 antibody of the present disclosure comprises a heavy chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.3 or the amino acid sequence of SEQ ID NO: 60, wherein the heavy chain variable domain comprises the amino acid sequence of HVR-H1, HVR-H2, and HVR-H3 of antibody AB-64.1.3.In some embodiments, an anti-CD33 antibody of the present disclosure comprises a light chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.3 or the amino acid sequence of SEQ ID NO: 86, wherein the light chain variable domain comprises the amino acid sequence of HVR-L1, HVR-L2, and HVR-L3 of antibody AB-64.1.3. In some embodiments, the anti-CD33 antibody comprises a heavy chain variable domain (VH) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.3 or the amino acid sequence of SEQ ID NO: 60, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence) but wherein the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.3 or the amino acid sequence of SEQ ID NO: 60. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.3 or the amino acid sequence of SEQ ID NO: 60. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VH sequence of antibody CD33 or SEQ ID NO: 60, including post-translational modifications of that sequence.In certain embodiments, the VH comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-H1 of antibody AB-64.1.3, (b) the amino acid sequence of HVR-H2 of antibody AB-64.1.3, and (c) the amino acid sequence of HVR-H3 of antibody AB-64.1.3. In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain (VL) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.3 or the amino acid sequence of SEQ ID NO: 86, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence) but wherein the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.3 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.3 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VL sequence of antibody AB-64.1.3 or SEQ ID NO: 86, including post-translational modifications of that sequence. In certain embodiments, the VL comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-L1 of antibody AB-64.1.3, (b) the amino acid sequence of HVR-L2 of antibody AB-64.1.3, and (c) the amino acid sequence of HVR-L3 of antibody AB-64.1.3.

[0178] In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain and a heavy chain variable domain, wherein the heavy chain variable domain has an amino acid sequence that is at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.4 or the amino acid sequence of SEQ ID NO: 61. and / or the light chain variable domain comprises an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.4 or the amino acid sequence of SEQ ID NO:86. In some embodiments, an anti-CD33 antibody of the present disclosure comprises a heavy chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.4 or the amino acid sequence of SEQ ID NO: 61, wherein the heavy chain variable domain comprises the amino acid sequence of HVR-H1, HVR-H2, and HVR-H3 of antibody AB-64.1.4.In some embodiments, an anti-CD33 antibody of the present disclosure comprises a light chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.4 or the amino acid sequence of SEQ ID NO: 86, wherein the light chain variable domain comprises the amino acid sequence of HVR-L1, HVR-L2, and HVR-L3 of antibody AB-64.1.4. In some embodiments, the anti-CD33 antibody comprises a heavy chain variable domain (VH) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.4 or the amino acid sequence of SEQ ID NO: 61, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence) but wherein the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.4 or the amino acid sequence of SEQ ID NO: 61. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.4 or the amino acid sequence of SEQ ID NO: 61. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VH sequence of antibody CD33 or SEQ ID NO: 61, including post-translational modifications of that sequence.In certain embodiments, the VH comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-H1 of antibody AB-64.1.4, (b) the amino acid sequence of HVR-H2 of antibody AB-64.1.4, and (c) the amino acid sequence of HVR-H3 of antibody AB-64.1.4. In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain (VL) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.4 or the amino acid sequence of SEQ ID NO: 86, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence) but wherein the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.4 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.4 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VL sequence of antibody AB-64.1.4 or SEQ ID NO: 86, including post-translational modifications of that sequence. In certain embodiments, the VL comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-L1 of antibody AB-64.1.4, (b) the amino acid sequence of HVR-L2 of antibody AB-64.1.4, and (c) the amino acid sequence of HVR-L3 of antibody AB-64.1.4.

[0179] In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain and a heavy chain variable domain, wherein the heavy chain variable domain has an amino acid sequence that is at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.5 or the amino acid sequence of SEQ ID NO: 62. and / or the light chain variable domain comprises an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.5 or the amino acid sequence of SEQ ID NO:86. In some embodiments, an anti-CD33 antibody of the present disclosure comprises a heavy chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.5 or the amino acid sequence of SEQ ID NO: 62, wherein the heavy chain variable domain comprises the amino acid sequence of HVR-H1, HVR-H2, and HVR-H3 of antibody AB-64.1.5.In some embodiments, an anti-CD33 antibody of the present disclosure comprises a light chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.5 or the amino acid sequence of SEQ ID NO: 86, wherein the light chain variable domain comprises the amino acid sequence of HVR-L1, HVR-L2, and HVR-L3 of antibody AB-64.1.5. In some embodiments, the anti-CD33 antibody comprises a heavy chain variable domain (VH) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.5 or the amino acid sequence of SEQ ID NO: 62, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence), but the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.5 or the amino acid sequence of SEQ ID NO: 62. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.5 or the amino acid sequence of SEQ ID NO: 62. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VH sequence of antibody CD33 or SEQ ID NO: 62, including post-translational modifications of that sequence.In certain embodiments, the VH comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-H1 of antibody AB-64.1.5, (b) the amino acid sequence of HVR-H2 of antibody AB-64.1.5, and (c) the amino acid sequence of HVR-H3 of antibody AB-64.1.5. In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain (VL) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.5 or the amino acid sequence of SEQ ID NO: 86, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence) but wherein the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.5 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.5 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VL sequence of antibody AB-64.1.5 or SEQ ID NO: 86, including post-translational modifications of that sequence. In certain embodiments, the VL comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-L1 of antibody AB-64.1.5, (b) the amino acid sequence of HVR-L2 of antibody AB-64.1.5, and (c) the amino acid sequence of HVR-L3 of antibody AB-64.1.5.

[0180] In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain and a heavy chain variable domain, wherein the heavy chain variable domain has an amino acid sequence that is at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.6 or the amino acid sequence of SEQ ID NO: 63. and / or the light chain variable domain comprises an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.6 or the amino acid sequence of SEQ ID NO:86. In some embodiments, an anti-CD33 antibody of the present disclosure comprises a heavy chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.6 or the amino acid sequence of SEQ ID NO: 63, wherein the heavy chain variable domain comprises the amino acid sequence of HVR-H1, HVR-H2, and HVR-H3 of antibody AB-64.1.6.In some embodiments, an anti-CD33 antibody of the present disclosure comprises a light chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.6 or the amino acid sequence of SEQ ID NO: 86, wherein the light chain variable domain comprises the amino acid sequence of HVR-L1, HVR-L2, and HVR-L3 of antibody AB-64.1.6. In some embodiments, the anti-CD33 antibody comprises a heavy chain variable domain (VH) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.6 or the amino acid sequence of SEQ ID NO: 63, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence), but the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.6 or the amino acid sequence of SEQ ID NO: 63. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.6 or the amino acid sequence of SEQ ID NO: 63. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VH sequence of antibody CD33 or SEQ ID NO: 63, including post-translational modifications of that sequence.In certain embodiments, the VH comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-H1 of antibody AB-64.1.6, (b) the amino acid sequence of HVR-H2 of antibody AB-64.1.6, and (c) the amino acid sequence of HVR-H3 of antibody AB-64.1.6. In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain (VL) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.6 or the amino acid sequence of SEQ ID NO: 86, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence) but wherein the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.6 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.6 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VL sequence of antibody AB-64.1.6 or SEQ ID NO: 86, including post-translational modifications of that sequence. In certain embodiments, the VL comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-L1 of antibody AB-64.1.6, (b) the amino acid sequence of HVR-L2 of antibody AB-64.1.6, and (c) the amino acid sequence of HVR-L3 of antibody AB-64.1.6.

[0181] In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain and a heavy chain variable domain, wherein the heavy chain variable domain has an amino acid sequence that is at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.7 or the amino acid sequence of SEQ ID NO: 64. and / or the light chain variable domain comprises an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.7 or the amino acid sequence of SEQ ID NO:86. In some embodiments, an anti-CD33 antibody of the present disclosure comprises a heavy chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.7 or the amino acid sequence of SEQ ID NO: 64, wherein the heavy chain variable domain comprises the amino acid sequence of HVR-H1, HVR-H2, and HVR-H3 of antibody AB-64.1.7.In some embodiments, an anti-CD33 antibody of the present disclosure comprises a light chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.7 or the amino acid sequence of SEQ ID NO: 86, wherein the light chain variable domain comprises the amino acid sequence of HVR-L1, HVR-L2, and HVR-L3 of antibody AB-64.1.7. In some embodiments, the anti-CD33 antibody comprises a heavy chain variable domain (VH) sequence having at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.7 or the amino acid sequence of SEQ ID NO: 64, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence) but wherein the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.7 or the amino acid sequence of SEQ ID NO: 64. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.7 or the amino acid sequence of SEQ ID NO: 64. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VH sequence of antibody CD33 or SEQ ID NO: 64, including post-translational modifications of that sequence.In certain embodiments, the VH comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-H1 of antibody AB-64.1.7, (b) the amino acid sequence of HVR-H2 of antibody AB-64.1.7, and (c) the amino acid sequence of HVR-H3 of antibody AB-64.1.7. In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain (VL) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.7 or the amino acid sequence of SEQ ID NO: 86, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence) but wherein the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.7 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.7 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VL sequence of antibody AB-64.1.7 or SEQ ID NO: 86, including post-translational modifications of that sequence. In certain embodiments, the VL comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-L1 of antibody AB-64.1.7, (b) the amino acid sequence of HVR-L2 of antibody AB-64.1.7, and (c) the amino acid sequence of HVR-L3 of antibody AB-64.1.7.

[0182] In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain and a heavy chain variable domain, wherein the heavy chain variable domain has an amino acid sequence that is at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.8 or the amino acid sequence of SEQ ID NO: 65. and / or the light chain variable domain comprises an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.8 or the amino acid sequence of SEQ ID NO:86. In some embodiments, an anti-CD33 antibody of the present disclosure comprises a heavy chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.8 or the amino acid sequence of SEQ ID NO: 65, wherein the heavy chain variable domain comprises the amino acid sequence of HVR-H1, HVR-H2, and HVR-H3 of antibody AB-64.1.8.In some embodiments, an anti-CD33 antibody of the present disclosure comprises a light chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.8 or the amino acid sequence of SEQ ID NO: 86, wherein the light chain variable domain comprises the amino acid sequence of HVR-L1, HVR-L2, and HVR-L3 of antibody AB-64.1.8. In some embodiments, the anti-CD33 antibody comprises a heavy chain variable domain (VH) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.8 or the amino acid sequence of SEQ ID NO: 65, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence) but wherein the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.8 or the amino acid sequence of SEQ ID NO: 65. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.8 or the amino acid sequence of SEQ ID NO: 65. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VH sequence of antibody CD33 or SEQ ID NO: 65, including post-translational modifications of that sequence.In certain embodiments, the VH comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-H1 of antibody AB-64.1.8, (b) the amino acid sequence of HVR-H2 of antibody AB-64.1.8, and (c) the amino acid sequence of HVR-H3 of antibody AB-64.1.8. In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain (VL) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.8 or the amino acid sequence of SEQ ID NO: 86, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence) but wherein the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.8 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.8 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VL sequence of antibody AB-64.1.8 or SEQ ID NO: 86, including post-translational modifications of that sequence. In certain embodiments, the VL comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-L1 of antibody AB-64.1.8, (b) the amino acid sequence of HVR-L2 of antibody AB-64.1.8, and (c) the amino acid sequence of HVR-L3 of antibody AB-64.1.8.

[0183] In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain and a heavy chain variable domain, wherein the heavy chain variable domain has an amino acid sequence that is at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.9 or the amino acid sequence of SEQ ID NO: 66. and / or the light chain variable domain comprises an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.9 or the amino acid sequence of SEQ ID NO:86. In some embodiments, an anti-CD33 antibody of the present disclosure comprises a heavy chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.9 or the amino acid sequence of SEQ ID NO: 66, wherein the heavy chain variable domain comprises the amino acid sequence of HVR-H1, HVR-H2, and HVR-H3 of antibody AB-64.1.9.In some embodiments, an anti-CD33 antibody of the present disclosure comprises a light chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.9 or the amino acid sequence of SEQ ID NO: 86, wherein the light chain variable domain comprises the amino acid sequence of HVR-L1, HVR-L2, and HVR-L3 of antibody AB-64.1.9. In some embodiments, the anti-CD33 antibody comprises a heavy chain variable domain (VH) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.9 or the amino acid sequence of SEQ ID NO: 66, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence), but the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.9 or the amino acid sequence of SEQ ID NO: 66. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.9 or the amino acid sequence of SEQ ID NO: 66. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VH sequence of antibody CD33 or SEQ ID NO: 66, including post-translational modifications of that sequence.In certain embodiments, the VH comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-H1 of antibody AB-64.1.9, (b) the amino acid sequence of HVR-H2 of antibody AB-64.1.9, and (c) the amino acid sequence of HVR-H3 of antibody AB-64.1.9. In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain (VL) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.9 or the amino acid sequence of SEQ ID NO: 86, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence), but wherein the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.9 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.9 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VL sequence of antibody AB-64.1.9 or SEQ ID NO: 86, including post-translational modifications of that sequence. In certain embodiments, the VL comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-L1 of antibody AB-64.1.9, (b) the amino acid sequence of HVR-L2 of antibody AB-64.1.9, and (c) the amino acid sequence of HVR-L3 of antibody AB-64.1.9.

[0184] In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain and a heavy chain variable domain, wherein the heavy chain variable domain has an amino acid sequence that is at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.10 or the amino acid sequence of SEQ ID NO: 67. and / or the light chain variable domain comprises an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.10 or the amino acid sequence of SEQ ID NO:86. In some embodiments, an anti-CD33 antibody of the present disclosure comprises a heavy chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.10 or the amino acid sequence of SEQ ID NO: 67, wherein the heavy chain variable domain comprises the amino acid sequence of HVR-H1, HVR-H2, and HVR-H3 of antibody AB-64.1.10.In some embodiments, an anti-CD33 antibody of the present disclosure comprises a light chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.10 or the amino acid sequence of SEQ ID NO: 86, wherein the light chain variable domain comprises the amino acid sequence of HVR-L1, HVR-L2, and HVR-L3 of antibody AB-64.1.10. In some embodiments, the anti-CD33 antibody comprises a heavy chain variable domain (VH) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.10 or the amino acid sequence of SEQ ID NO: 67, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence), but the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.10 or the amino acid sequence of SEQ ID NO: 67. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.10 or the amino acid sequence of SEQ ID NO: 67. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VH sequence of antibody CD33 or SEQ ID NO: 67, including post-translational modifications of that sequence.In certain embodiments, the VH comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-H1 of antibody AB-64.1.10, (b) the amino acid sequence of HVR-H2 of antibody AB-64.1.10, and (c) the amino acid sequence of HVR-H3 of antibody AB-64.1.10. In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain (VL) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.10 or the amino acid sequence of SEQ ID NO: 86, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence) but such anti-CD33 antibodies retain the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.10 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.10 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VL sequence of antibody AB-64.1.10 or SEQ ID NO: 86, including post-translational modifications of that sequence. In certain embodiments, the VL comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-L1 of antibody AB-64.1.10, (b) the amino acid sequence of HVR-L2 of antibody AB-64.1.10, and (c) the amino acid sequence of HVR-L3 of antibody AB-64.1.10.

[0185] In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain and a heavy chain variable domain, wherein the heavy chain variable domain has an amino acid sequence that is at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.11 or the amino acid sequence of SEQ ID NO: 68. and / or the light chain variable domain comprises an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.11 or the amino acid sequence of SEQ ID NO: 86. In some embodiments, an anti-CD33 antibody of the present disclosure comprises a heavy chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.11 or the amino acid sequence of SEQ ID NO: 68, wherein the heavy chain variable domain comprises the amino acid sequence of HVR-H1, HVR-H2, and HVR-H3 of antibody AB-64.1.11.In some embodiments, an anti-CD33 antibody of the present disclosure comprises a light chain variable domain comprising an amino acid sequence with at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.11 or the amino acid sequence of SEQ ID NO: 86, wherein the light chain variable domain comprises the amino acid sequence of HVR-L1, HVR-L2, and HVR-L3 of antibody AB-64.1.11. In some embodiments, the anti-CD33 antibody comprises a heavy chain variable domain (VH) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.11 or the amino acid sequence of SEQ ID NO: 68, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence), but the anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.11 or the amino acid sequence of SEQ ID NO: 68. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the heavy chain variable domain of antibody AB-64.1.11 or the amino acid sequence of SEQ ID NO: 68. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VH sequence of antibody CD33 or SEQ ID NO: 68, including post-translational modifications of that sequence.In certain embodiments, the VH comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-H1 of antibody AB-64.1.11, (b) the amino acid sequence of HVR-H2 of antibody AB-64.1.11, and (c) the amino acid sequence of HVR-H3 of antibody AB-64.1.11. In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain (VL) sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identity to the amino acid sequence of the light chain variable domain of antibody AB-64.1.11 or the amino acid sequence of SEQ ID NO: 86, and contains substitutions (e.g., conservative substitutions, insertions, or deletions relative to the reference sequence), but such anti-CD33 antibodies retain the ability to bind to CD33. In certain embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.11 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, a total of 1 to 5 amino acids are substituted, inserted, and / or deleted in the amino acid sequence of the light chain variable domain of antibody AB-64.1.11 or the amino acid sequence of SEQ ID NO: 86. In certain embodiments, the substitutions, insertions, or deletions occur in regions outside the HVRs (i.e., FR regions). In some embodiments, the substitutions, insertions, or deletions occur within the FR regions. Optionally, the anti-CD33 antibody comprises the VL sequence of antibody AB-64.1.11 or SEQ ID NO: 86, including post-translational modifications of that sequence. In certain embodiments, the VL comprises one, two, or three HVRs selected from (a) the amino acid sequence of HVR-L1 of antibody AB-64.1.11, (b) the amino acid sequence of HVR-L2 of antibody AB-64.1.11, and (c) the amino acid sequence of HVR-L3 of antibody AB-64.1.11.

[0186] In some embodiments, an anti-CD33 antibody of the disclosure comprises a light chain variable domain and a heavy chain variable domain, wherein the heavy chain variable domain has an amino acid sequence that is at least 85%, at least 86%, at least 87%, at ...

Claims

1. An antibody that binds to a CD33 protein, comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region is Formula I: GX １ X ２ X ３ TDYNX ４ HVR-H1 comprising the sequence of H (SEQ ID NO: 152), wherein X １ is Y, A, or V, and X ２ is T or A, and X ３ is F, E, or H, and X ４ is L, F, Y, or N; Formula II: FIYPX １ NX ２ IX ３ HVR-H2 comprising the sequence of X (SEQ ID NO: 153), １ is S or A, and X ２ is G, Q, R, or V, and X ３ is T or R, and Formula III: SX １ VDYFDX ２ HVR-H3 comprising the sequence of (SEQ ID NO: 154), wherein X １ is T, D, F, or S, and X ２ is Y, D, or L, The antibody is not an antibody comprising a heavy chain variable region comprising HVR-H1 comprising the sequence GYTFTDYNLH (SEQ ID NO: 105), HVR-H2 comprising the sequence FIYPSNGITG (SEQ ID NO: 115), and HVR-H3 comprising the sequence STVDYFDY (SEQ ID NO: 121).

2. An antibody that binds to a CD33 protein, comprising a heavy chain variable region and a light chain variable region, wherein the light chain variable region is Formula IV:X １ X ２ SQX ３ VX ４ X ５ HVR-L1 comprising the sequence of STYSYMH (SEQ ID NO: 155), wherein X １ is R or K, and X ２ is A, G, or V, and X ３ is S or D, and X ４ is S, G, or H, and X ５ is T or A, Formula V: YX １ X ２ X ３ X ４ X ５ S (SEQ ID NO: 156), wherein X １ is A, V, or E, and X ２ is S, V, or F, and X ３ is N, A, Y, or F, and X ４ is L or V, and X ５ is E, G, or N; and Formula VI:X １ HSX ２ X ３ X ４ PLX ５ HVR-L3 comprising the sequence of (SEQ ID NO: 157), wherein X １ is Q or E, and X ２ is W or E, and X ３ is E or A, and X ４ is I or L, and X ５ is the antibody, including those in which is T or E, The antibody is not an antibody comprising a light chain variable region comprising HVR-L1 comprising the sequence of RASQSVSSTYSYMH (SEQ ID NO: 127), HVR-L2 comprising the sequence of YASNLES (SEQ ID NO: 135), and HVR-L3 comprising the sequence of QHSWEIPLT (SEQ ID NO: 146).

3. An antibody that binds to a CD33 protein, comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region is Formula I: GX １ X ２ X ３ TDYNX ４ HVR-H1 comprising the sequence of H (SEQ ID NO: 152), wherein X １ is Y, A, or V, and X ２ is T or A, and X ３ is F, E, or H, and X ４ is L, F, Y, or N; Formula II: FIYPX １ NX ２ IX ３ HVR-H2 comprising the sequence of X (SEQ ID NO: 153), １ is S or A, and X ２ is G, Q, R, or V, and X ３ is T or R, and Formula III: SX １ VDYFDX ２ HVR-H3 comprising the sequence of (SEQ ID NO: 154), wherein X １ is T, D, F, or S, and X ２ is Y, D, or L, and the light chain variable region is Formula IV:X １ X ２ SQX ３ VX ４ X ５ HVR-L1 comprising the sequence of STYSYMH (SEQ ID NO: 155), wherein X １ is R or K, and X ２ is A, G, or V, and X ３ is S or D, and X ４ is S, G, or H, and X ５ is T or A, Formula V: YX １ X ２ X ３ X ４ X ５ S (SEQ ID NO: 156), wherein X １ is A, V, or E, and X ２ is S, V, or F, and X ３ is N, A, Y, or F, and X ４ is L or V, and X ５ is E, G, or N; and Formula VI:X １ HSX ２ X ３ X ４ PLX ５ HVR-L3 comprising the sequence of (SEQ ID NO: 157), wherein X １ is Q or E, and X ２ is W or E, and X ３ is E or A, and X ４ is I or L, and X ５ is the antibody, including those in which is T or E, The antibody is not an antibody comprising a heavy chain variable region comprising HVR-H1 comprising the sequence of GYTFTDYNLH (SEQ ID NO: 105), HVR-H2 comprising the sequence of FIYPSNGITG (SEQ ID NO: 115), and HVR-H3 comprising the sequence of STVDYFDY (SEQ ID NO: 121), and a light chain variable region comprising HVR-L1 comprising the sequence of RASQSVSSTTYSYMH (SEQ ID NO: 127), HVR-L2 comprising the sequence of YASNLES (SEQ ID NO: 135), and HVR-L3 comprising the sequence of QHSWEIPLT (SEQ ID NO: 146).

4. 1. An antibody that binds to CD33 protein, comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region is selected from the group consisting of antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-63.19, AB-63.20, AB-63.21, AB-63.22, AB-63.23, AB-63.24, AB-63.25, AB-63.26, AB-63.27, AB-63.28, AB-63.29, AB-63.30, AB-63.31, AB-63.32, AB-63.33, AB-63.34, AB-63.35, AB-63.36, AB-63.37, AB-63.38, AB-63.39, AB-63.40, AB-63.41, AB-63.42, AB-63.43, AB-63.44, AB-63.45, AB-63.46, AB-63.47, AB-63. -64.1, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-6 The antibody comprises HVR-H1, HVR-H2, and HVR-H3 of AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 (as shown in Tables 9A-9C).

5. an antibody that binds to the CD33 protein, comprising a heavy chain variable region and a light chain variable region, wherein the light chain variable region is selected from the group consisting of antibodies AB-14.3, AB-14.4, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, and AB-63 AB-63.11, AB-63.12, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, or AB-64.8 (as shown in Tables 10A-10C).

6. An antibody that binds to CD33 protein, comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region is selected from the group consisting of antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.8, AB-63.9, AB-63.10, AB-63.11, and AB-63.1 2, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB- 64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1 AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 (as set forth in Tables 9A-9C), wherein the light chain variable region comprises the HVR-H1, HVR-H2, and HVR-H3 sequences of antibodies AB-14.3, AB-14.4, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.6, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.

15. AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, or AB-64.8 (as shown in Tables 10A-10C).

7. an antibody that binds to the CD33 protein, the antibody comprising a heavy chain variable region comprising HVR-H1, HVR-H2, and HVR-H3 and a light chain variable region comprising HVR-L1, HVR-L2, and HVR-L3; and antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-1 4.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63. 9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB- 63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64. 1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB- The antibody comprises the HVR-H1, HVR-H2, HVR-H3, HVR-L1, HVR-L2, and HVR-L3 of AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 (as shown in Tables 9A-9C and 10A-10C).

8. the heavy chain variable region comprises one, two, three, or four framework regions selected from VH FR1, VH FR2, VH FR3, and VH FR4; VH FR1 has the formula VII: QVQLVQSGAEVKKPGX １ SVKX ２ SCKAS (SEQ ID NO: 158), wherein X １ is A or S, and X ２ is V or I, VH FR2 comprises the sequence of SEQ ID NO: 5; VH FR3 has the formula VIII:X １ AX ２ X ３ X ４ X ５ X ６ RX ７ TX ８ TVDX ９ X １０ X １１ STX １２ YMELSSLRSEDTAVYYCAR (SEQ ID NO: 159), wherein X １ is Y or S, and X ２ is Q or E, and X ３ is K or D, and X ４ is F or D, and X ５ is Q, F, E, or T, and X ６ is G, D, or H, and X ７ is V or A, and X ８ is M or L, and X ９ is T, N, or Q, and X １０ is S or P, and X １１ is T or A, and X １２ is V or A, VH FR4 is of formula IX: WGQGTLX １ TVSS (SEQ ID NO: 160), wherein X １ is V or L, and / or the light chain comprises one, two, three, or four framework regions selected from VL FR1, VL FR2, VL FR3, and VL FR4; VL FR1 is a group of the formula X:X １ IX ２ X ３ TQSPX ４ SLX ５ X ６ SX ７ GX ８ RX ９ TIX １０ C (SEQ ID NO: 161), wherein X １ is D or G, and X ２ is Q or V, and X ３ is M or L, and X ４ is S or D, and X ５ is S, P, or A, and X ６ is A or V, and X ７ is V or L, and X ８ is D or E, and X ９ is V or A, and X １０ is T, N, or D; VL FR2 is represented by Formula XI: WYQQKPGX １ X ２ PKLLIK (SEQ ID NO: 162), wherein X １ is K or Q, and X ２ is A or P, VL FR3 is represented by Formula XII: GVPX １ RFSGSGSGTDFTLISSLQX ２ EDX ３ AX ４ YYC (SEQ ID NO: 163), wherein X １ is S or D, and X ２ is P or A, and X ３ is F, L, or V, and X ４ is T or V, VL FR4 has the formula XIII: FGQGTKLEIX １ (SEQ ID NO: 164), wherein X １ The antibody according to any one of claims 1 to 7, wherein is K or E.

9. the heavy chain variable region comprises one, two, three, or four framework regions selected from VH FR1, VH FR2, VH FR3, and VH FR4; VH FR1 comprises a sequence selected from the group consisting of SEQ ID NOs: 2-4; VH FR2 comprises the sequence of SEQ ID NO: 5; VH FR3 comprises a sequence selected from the group consisting of SEQ ID NOs: 6-19; VH FR4 comprises a sequence selected from the group consisting of SEQ ID NOs: 20-21, and / or the light chain comprises one, two, three, or four framework regions selected from VL FR1, VL FR2, VL FR3, and VL FR4; VL FR1 comprises a sequence selected from the group consisting of SEQ ID NOs: 22-26; VL FR2 comprises a sequence selected from the group consisting of SEQ ID NOs: 27-28; VL FR3 comprises a sequence selected from the group consisting of SEQ ID NOs: 29-31; The antibody of any one of claims 1 to 8, wherein VL FR4 comprises a sequence selected from the group consisting of SEQ ID NOs: 32 to 33.

10. The antibody according to any one of claims 1 to 9, comprising a heavy chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 34 to 72, and / or a light chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 77 to 101.

11. 11. The antibody of claim 10, comprising antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB- or AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 heavy chain variable region (as shown in Table 13). The above antibodies and / or antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, The foregoing antibodies comprise the light chain variable region of AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 (as shown in Table 14).

12. The antibody according to any one of claims 1 to 11, (a) the HVR-H1 comprises the amino acid sequence GYTFTDYNLH (SEQ ID NO: 105); the HVR-H2 comprises the amino acid sequence FIYPSNRITG (SEQ ID NO: 119); the HVR-H3 comprises the amino acid sequence SDDVDYFDY (SEQ ID NO: 122); the HVR-L1 comprises the amino acid sequence RASQSVSSTTYSYMH (SEQ ID NO: 127); the HVR-L2 comprises the amino acid sequence YASNLES (SEQ ID NO: 135); the HVR-L3 comprises the amino acid sequence QHSWEIPLT (SEQ ID NO: 146); or (b) the HVR-H1 comprises the amino acid sequence GYTFTDYNLH (SEQ ID NO: 105); the HVR-H2 comprises the amino acid sequence FIYPSNQITG (SEQ ID NO: 118); the HVR-H3 comprises the amino acid sequence SDDVDYFDY (SEQ ID NO: 122); the HVR-L1 comprises the amino acid sequence RASQSVSSTTYSYMH (SEQ ID NO: 127); the HVR-L2 comprises the amino acid sequence YASNLES (SEQ ID NO: 135); The antibody, wherein the HVR-L3 comprises the amino acid sequence QHSWEIPLT (SEQ ID NO: 146).

13. An antibody that binds to a CD33 protein, comprising a heavy chain variable region and a light chain variable region, (a) the heavy chain variable region is HVR-H1 comprising the amino acid sequence GYTFTDYNLH (SEQ ID NO: 105); HVR-H2 comprising the amino acid sequence FIYPSNRITG (SEQ ID NO: 119), and HVR-H3 comprising the amino acid sequence SDDVDYFDY (SEQ ID NO: 122); the light chain variable region HVR-L1 comprising the amino acid sequence RASQSVSSTTYSYMH (SEQ ID NO: 127); HVR-L2 comprising the amino acid sequence YASNLES (SEQ ID NO: 135), and an HVR-L3 comprising the amino acid sequence QHSWEIPLT (SEQ ID NO: 146); or (b) the heavy chain is HVR-H1 comprising the amino acid sequence GYTFTDYNLH (SEQ ID NO: 105); HVR-H2 comprising the amino acid sequence FIYPSNQITG (SEQ ID NO: 118), and HVR-H3 comprising the amino acid sequence SDDVDYFDY (SEQ ID NO: 122), wherein the light chain variable region comprises: HVR-L1 comprising the amino acid sequence RASQSVSSTTYSYMH (SEQ ID NO: 127); HVR-L2 comprising the amino acid sequence YASNLES (SEQ ID NO: 135), and The antibody, comprising an HVR-L3 comprising the amino acid sequence QHSWEIPLT (SEQ ID NO: 146).

14. An antibody that binds to CD33 protein, the antibody comprising a heavy chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 34 to 72, and / or a light chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 77 to 101.

15. 15. The antibody of claim 14, comprising antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB- or AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 heavy chain variable region (as shown in Table 13). The above antibodies and / or antibodies AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB-63.18, AB-64.1, The foregoing antibodies comprise the light chain variable region of AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.1.14, or AB-64.1.15 (as shown in Table 14).

16. 16. The antibody of claim 14 or 15, (a) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 59, and / or the light chain variable region comprises the amino acid sequence of SEQ ID NO: 86, or (b) the antibody, wherein the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 65, and / or the light chain variable region comprises the amino acid sequence of SEQ ID NO:

86.

17. An antibody that binds to a CD33 protein, the antibody comprising a heavy chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 34, 40, 42, 52, 53, and 73 to 76, and / or a light chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 77, 86, and 102.

18. 18. The antibody of claim 17, comprising the heavy chain variable region of antibody AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, or AB-H66 (as shown in Table 13), and / or the light chain variable region of antibody AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, or AB-H66 (as shown in Table 14).

19. An antibody that binds to a CD33 protein, comprising a heavy chain variable region and a light chain variable region, the heavy chain variable region Formula I: GX １ X ２ X ３ TDYNX ４ HVR-H1 comprising the sequence of H (SEQ ID NO: 186), wherein X １ is Y or V, and X ２ is T or A, and X ３ is F, E, or H, and X ４ is L, F, Y, or N; Formula II: FIYPX １ NX ２ IX ３ HVR-H2 comprising the sequence of X (SEQ ID NO: 153), １ is S or A, and X ２ is G, Q, R, or V, and X ３ is T or R, and Formula III: SX １ VDYFDX ２ HVR-H3 comprising the sequence of (SEQ ID NO: 187), wherein X １ is T, D, or F, and X ２ is Y, D, or L; the light chain variable region Formula IV:X １ X ２ SQX ３ VX ４ X ５ HVR-L1 comprising the sequence of STYSYMH (SEQ ID NO: 188), wherein X １ is R or K, and X ２ is A, G, or V, and X ３ is S or D, and X ４ is S, G, or H, and X ５ is T, Formula V: YX １ X ２ X ３ X ４ X ５ S (SEQ ID NO: 189), wherein X １ is A or E, and X ２ is S or F, and X ３ is N, Y, or F, and X ４ is L or V, and X ５ is E or N, and Formula VI:X １ HSX ２ X ３ X ４ PLX ５ HVR-L3 comprising the sequence of (SEQ ID NO: 157), wherein X １ is Q or E, and X ２ is W or E, and X ３ is E or A, and X ４ is I or L, and X ５ is T or E.

20. An antibody that binds to a CD33 protein, comprising a heavy chain variable region and a light chain variable region, the heavy chain variable region HVR-H1 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 105 and 108-114; HVR-H2 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 115-120; and HVR-H3 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 121-123 and 125-126; HVR-L1, wherein the light chain variable region comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 127-128 and 130-134; HVR-L2 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 135 and 140-145; and The antibody, comprising an HVR-L3 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 146 to 151.

21. the heavy chain variable region comprises one, two, three, or four framework regions selected from VH FR1, VH FR2, VH FR3, and VH FR4; VH FR1 has the formula VII: QVQLVQSGAEVKKPGX １ SVKX ２ SCKAS (SEQ ID NO: 158), wherein X １ is A or S, and X ２ is V or I, VH FR2 comprises the sequence of SEQ ID NO: 5; VH FR3 has the formula VIII:X １ AX ２ X ３ X ４ X ５ X ６ RX ７ TX ８ TVDX ９ X １０ X １１ STX １２ YMELSSLRSEDTAVYYCAR (SEQ ID NO: 159), wherein X １ is Y or S, and X ２ is Q or E, and X ３ is K or D, and X ４ is F or D, and X ５ is Q, F, E, or T, and X ６ is G, D, or H, and X ７ is V or A, and X ８ is M or L, and X ９ is T, N, or Q, and X １０ is S or P, and X １１ is T or A, and X １２ is V or A, VH FR4 is of formula IX: WGQGTLX １ TVSS (SEQ ID NO: 160), wherein X １ is V or L, and / or the light chain comprises one, two, three, or four framework regions selected from VL FR1, VL FR2, VL FR3, and VL FR4; VL FR1 is a group of the formula X:X １ IX ２ X ３ TQSPX ４ SLX ５ X ６ SX ７ GX ８ RX ９ TIX １０ C (SEQ ID NO: 161), wherein X １ is D or G, and X ２ is Q or V, and X ３ is M or L, and X ４ is S or D, and X ５ is S, P, or A, and X ６ is A or V, and X ７ is V or L, and X ８ is D or E, and X ９ is V or A, and X １０ is T, N, or D; VL FR2 is represented by Formula XI: WYQQKPGX １ X ２ PKLLIK (SEQ ID NO: 162), wherein X １ is K or Q, and X ２ is A or P, VL FR3 is represented by Formula XII: GVPX １ RFSGSGSGTDFTLISSLQX ２ EDX ３ AX ４ YYC (SEQ ID NO: 163), wherein X １ is S or D, and X ２ is P or A, and X ３ is F, L, or V, and X ４ is T or V, VL FR4 has the formula XIII: FGQGTKLEIX １ (SEQ ID NO: 164), wherein X １ The antibody of claim 19 or claim 20, wherein is K or E.

22. the heavy chain variable region comprises one, two, three, or four framework regions selected from VH FR1, VH FR2, VH FR3, and VH FR4; VH FR1 comprises a sequence selected from the group consisting of SEQ ID NOs: 2-4; VH FR2 comprises the sequence of SEQ ID NO: 5; VH FR3 comprises a sequence selected from the group consisting of SEQ ID NOs: 6-19; VH FR4 comprises a sequence selected from the group consisting of SEQ ID NOs: 20-21, and / or the light chain comprises one, two, three, or four framework regions selected from VL FR1, VL FR2, VL FR3, and VL FR4; VL FR1 comprises a sequence selected from the group consisting of SEQ ID NOs: 22-26; VL FR2 comprises a sequence selected from the group consisting of SEQ ID NOs: 27-28; VL FR3 comprises a sequence selected from the group consisting of SEQ ID NOs: 29-31; The antibody of any one of claims 19 to 21, wherein VL FR4 comprises a sequence selected from the group consisting of SEQ ID NOs: 32 to 33.

23. The antibody of any one of claims 19 to 22, wherein the heavy chain variable region comprises a VH FR3 comprising a sequence selected from the group consisting of SEQ ID NOs: 12 to 15.

24. An antibody that binds to a CD33 protein, the antibody comprising a heavy chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 38 and 40 to 72, and / or a light chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 86 to 101.

25. An antibody that binds to CD33 protein, comprising: a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:58 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:86; a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:59 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:86; a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:65 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:86; a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:66 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:86; a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:67 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:86; a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:68 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:86; or a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:69 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:

86.

26. The antibody according to any one of claims 1 to 25, which is an antibody of the IgG class, IgM class, or IgA class.

27. 27. The antibody of claim 26, which is an IgG class antibody and has an IgG1, IgG2, IgG3, or IgG4 isotype.

28. 28. The antibody of claim 27, having an IgG4 isotype and comprising an amino acid substitution of S228P at residue position 228, an amino acid substitution of F234A at residue position 234, and an amino acid substitution of L235A at residue position 235, wherein the numbering of the residue positions is according to EU numbering.

29. 28. The antibody of claim 27, comprising one or more amino acid substitutions in the Fc region at residue positions selected from the group consisting of C127S, L234A, L234F, L235A, L235E, S267E, K322A, L328F, A330S, P331S, E345R, E430G, S440Y, and any combination thereof, wherein the numbering of said residues is according to EU or Kabat numbering.

30. 30. The antibody of claim 29, (a) the Fc region comprises an amino acid substitution at position E430G, wherein the numbering of residue positions is according to EU numbering; or (b) the Fc region comprises amino acid substitutions at positions L243A, L235A, and P331A, wherein the numbering of residue positions is according to EU numbering; or (c) the Fc region comprises amino acid substitutions at positions L243A, L235A, P331A, and E430G, wherein the numbering of residue positions is according to EU numbering; (d) the Fc region comprises amino acid substitutions at positions K322A and E430G, wherein the numbering of residue positions is according to EU numbering; (e) the Fc region comprises amino acid substitutions at positions P331S and E430G, wherein the numbering of residue positions is according to EU numbering; (f) the Fc region comprises amino acid substitutions at positions A330S, P331S, and E430G, wherein the numbering of residue positions is according to EU numbering; (g) the Fc region comprises amino acid substitutions at positions K322A, A330S, and P331S, wherein the numbering of residue positions is according to EU numbering; (h) the Fc region comprises amino acid substitutions at positions K322A, P331S, and E430G, wherein the numbering of residue positions is according to EU numbering; (i) the Fc region comprises an amino acid substitution at position E430G, wherein the numbering of residue positions is according to EU numbering; or (j) the Fc region comprises amino acid substitutions at positions A330S, P331S, and E430G, wherein the numbering of residue positions is according to EU numbering; (k) the Fc region comprises amino acid substitutions at positions S267E and L328F, wherein the numbering of residue positions is according to EU numbering; (l) the Fc region comprises an amino acid substitution at position C127S, wherein the numbering of residue positions is according to EU numbering; (m) the Fc region comprises amino acid substitutions at positions E345R, E430G, and S440Y, wherein the numbering of residue positions is according to EU numbering; or (n) The antibody, wherein the Fc region comprises amino acid substitutions at positions L243A, L235A, and P331S, wherein the numbering of residue positions is according to EU numbering.

31. The antibody of any one of claims 1 to 30, wherein the CD33 protein is a mammalian or human protein.

32. The antibody of any one of claims 1 to 31, wherein the CD33 protein is a wild-type protein.

33. The antibody of any one of claims 1 to 31, wherein the CD33 protein is a naturally occurring variant.

34. The antibody of any one of claims 1 to 33, wherein the CD33 protein is expressed on one or more cells selected from the group consisting of human dendritic cells, human macrophages, human monocytes, human osteoclasts, human neutrophils, human T cells, human T helper cells, human cytotoxic T cells, human granulocytes, and human microglia.

35. The antibody of any one of claims 1 to 34, which specifically binds to human CD33 protein.

36. The antibody of any one of claims 1 to 35, which is an antibody fragment that binds to an epitope comprising amino acid residues of human CD33 or mammalian CD33 protein.

37. The antibody of any one of claims 1 to 35, which is an antibody fragment that binds to one or more human proteins selected from the group consisting of human CD33, naturally occurring variants of human CD33, and disease variants of human CD33.

38. The antibody of claim 36 or claim 37, wherein the antibody fragment is crosslinked to a second antibody fragment that binds to one or more human proteins selected from the group consisting of human CD33, naturally occurring variants of human CD33, and disease variants of human CD33.

39. The antibody of any one of claims 36 to 38, wherein the fragment is a Fab, Fab', Fab'-SH, F(ab')2, Fv, or scFv fragment.

40. 40. The antibody of any one of claims 1 to 39, which is a humanized antibody, a bispecific antibody, a monoclonal antibody, a multivalent antibody, a composite antibody, or a chimeric antibody.

41. The antibody according to any one of claims 1 to 40, which is a monoclonal antibody.

42. The antibody according to any one of claims 1 to 40, which is a bispecific antibody that recognizes a first antigen and a second antigen.

43. The first antigen is CD33, and the second antigen is (a) an antigen that facilitates transport across the blood-brain barrier; (b) an antigen that promotes transport across the blood-brain barrier selected from the group consisting of transferrin receptor (TR), insulin receptor (HIR), insulin-like growth factor receptor (IGFR), low-density lipoprotein receptor-related proteins 1 and 2 (LPR-1 and 2), diphtheria toxin receptor, CRM197, llama single domain antibody, TMEM 30(A), protein transduction domain, TAT, Syn-B, penetratin, polyarginine peptides, angiopep peptides, and ANG1005; (c) a pathogen selected from the group consisting of a pathogenic peptide or protein and a pathogenic nucleic acid, wherein the pathogenic peptide or protein is selected from the group consisting of amyloid beta, oligomeric amyloid beta, amyloid beta plaques, amyloid precursor protein or a fragment thereof, tau, IAPP, alpha-synuclein, TDP-43, FUS protein, C9orf72 (chromosome 9 open reading frame 72), c9RAN protein, prion protein, PrPSc, huntingtin, calcitonin, superoxide dismutase, ataxin, ataxin 1, ataxin 2, ataxin 3, ataxin 7, ataxin 8, ataxin 10, Lewy bodies, atrial natriuretic factor, pancreatic islet amyloid polypeptide, the pathogen nucleic acid is selected from the group consisting of peptides, insulin, apolipoprotein AI, serum amyloid A, medin, prolactin, transthyretin, lysozyme, beta-2 microglobulin, gelsolin, keratoepithelin, cystatin, immunoglobulin light chain AL, S-IBM protein, repeat-associated non-ATG (RAN) translation products, dipeptide repeat (DPR) peptides, glycine-alanine (GA) repeat peptides, glycine-proline (GP) repeat peptides, glycine-arginine (GR) repeat peptides, proline-alanine (PA) repeat peptides, ubiquitin, and proline-arginine (PR) repeat peptides, and the pathogen nucleic acid is an antisense GGCCCC (G2C4) repeat expansion RNA; (d) a ligand and / or protein expressed on an immune cell, the ligand and / or protein being selected from the group consisting of CD40, OX40, ICOS, CD28, CD137 / 4-1BB, CD27, GITR, PD-L1, CTLA4, PD-L2, PD-1, B7-H3, B7-H4, HVEM, LIGHT, BTLA, CD38, TIGIT, VISTA, KIR, GAL9, TIM1, TIM3, TIM4, A2AR, LAG3, DR5, CD39, CD70, CD73, TREM1, TREM2, Siglec-5, Siglec-7, Siglec-9, Siglec-11, SirpA, CD47, CSF1 receptor, and phosphatidylserine; and (e) the antibody of claim 42, which is a protein, lipid, polysaccharide, or glycolipid expressed in one or more tumor cells.

44. Pathogenic peptide, pathogenic protein, amyloid beta, oligomeric amyloid beta, amyloid beta plaque, amyloid precursor protein or a fragment thereof, tau, IAPP, alpha-synuclein, TDP-43, FUS protein, C9orf72 (chromosome 9 open reading frame 72), prion protein, PrPSc, huntingtin, calcitonin, superoxide dismutase, ataxin, ataxin 1, ataxin 2, ataxin 3, ataxin 7, ataxin 8, ataxin 10, Lewy corpuscle, atrial natriuretic factor, islet amyloid polypeptide, insulin, apolipoprotein AI, serum amyloid A, medin, prolactin, transthyretin, lysozyme, beta-2 microglobulin, gelsolin, keratoepithelin, cystatin, immunoglobulin light chain AL, S-IBM protein, repeat-associated non-ATG (RAN) translation products, dipeptide repeat (DPR) peptide, glycine-alanine (GA) repeat peptide, glycine-proline (GP) repeat peptide, glycine-arginine (GR) repeat In combination with one or more antibodies that specifically bind to a pathogen selected from the group consisting of: a peptide, a proline-alanine (PA) repeat peptide, ubiquitin, and a proline-arginine (PR) repeat peptide, and any combination thereof, or CD40, OX40, ICOS, CD28, CD137 / 4-1BB, CD27, GITR, PD-L1, CTLA4, PD-L2, PD-1, B7-H3, B7-H4, HVEM, LIGHT, BTLA, CD38, TIGIT, VISTA, KIR, GAL9, TI 44. The antibody of any one of claims 1 to 43, used in combination with one or more antibodies that bind to an immunomodulatory protein selected from the group consisting of M1, TIM3, TIM4, A2AR3, DR5, CD39, CD70, CD73, LAG3, TREM1, TREM2, Siglec-5, Siglec-7, Siglec-9, Siglec-11, SirpA, CD47, CSF1 receptor, phosphatidylserine, pathogenic nucleic acid, antisense GGCCCC (G2C4) repeat expanded RNA, and any combination thereof.

45. Dissociation constant (K Ｄ ) is at least 4-fold lower than that of an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77, or at least 1-fold lower than that of an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, or at least 1-fold lower than that of an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 52 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, Ｄ The antibody of any one of claims 1 to 44, wherein is measured by surface plasmon resonance.

46. Dissociation constant (K Ｄ ) is in the range of about 2 nM to about 200 pM or less than about 200 pM, Ｄ The antibody of any one of claims 1 to 44, wherein is measured by BioLayer interferometry.

47. The antibody of any one of claims 1 to 46, which reduces cell surface CD33 levels.

48. 48. The antibody of claim 47, wherein the CD33 is expressed on the surface of human dendritic cells.

49. 49. The antibody of claim 47 or claim 48, which reduces cell surface CD33 levels in vitro.

50. Cell surface CD33 levels were measured in vitro by flow cytometry and showed a half maximal effective concentration (EC ) of less than 150 pM. ５０ The antibody according to any one of claims 47 to 49, wherein the antibody is reduced by

51. The cell surface CD33 level is measured in vitro by flow cytometry and is at least 50% lower than that of an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 77, at least 10% lower than that of an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 40 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, at least 10% lower than that of an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 52 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 86, or at least 10-fold lower than that of an anti-CD33 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 103 and a light chain variable region comprising the amino acid sequence of SEQ ID NO:

104. ５０ The antibody according to any one of claims 47 to 50, which reduces the

52. AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-14. 9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9, AB- 63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63.17, AB -63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, AB-64.1.7, A B-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1.13, AB-64.

1.

52. The antibody of any one of claims 1 to 51, which competes for binding to CD33 with one or more antibodies selected from the group consisting of: AB-64.1.14, AB-64.1.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, AB-H66, and any combination thereof.

53. AB-14.1, AB-14.2, AB-14.3, AB-14.4, AB-14.5, AB-14.6, AB-14.7, AB-14.8, AB-1 4.9, AB-14.10, AB-14.11, AB-63.4, AB-63.5, AB-63.6, AB-63.7, AB-63.8, AB-63.9 , AB-63.10, AB-63.11, AB-63.12, AB-63.13, AB-63.14, AB-63.15, AB-63.16, AB-63 .17, AB-63.18, AB-64.1, AB-64.2, AB-64.3, AB-64.4, AB-64.5, AB-64.6, AB-64.7, AB-64.8, AB-64.1.1, AB-64.1.2, AB-64.1.3, AB-64.1.4, AB-64.1.5, AB-64.1.6, A B-64.1.7, AB-64.1.8, AB-64.1.9, AB-64.1.10, AB-64.1.11, AB-64.1.12, AB-64.1 52. The antibody of any one of claims 1 to 51, which binds to essentially the same CD33 epitope as an antibody selected from the group consisting of AB-64.1.13, AB-64.1.14, AB-64.1.15, AB-H2, AB-H9, AB-H14, AB-H15, AB-H63, AB-H64, AB-H65, and AB-H66.

54. An antibody that binds to CD33 protein, (a) a heavy chain comprising the amino acid sequence of SEQ ID NO: 176 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; (b) a heavy chain comprising the amino acid sequence of SEQ ID NO: 197 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; (c) a heavy chain comprising the amino acid sequence of SEQ ID NO: 177 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; (d) a heavy chain comprising the amino acid sequence of SEQ ID NO: 198 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; (e) a heavy chain comprising the amino acid sequence of SEQ ID NO: 178 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; (f) a heavy chain comprising the amino acid sequence of SEQ ID NO: 199 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; (g) a heavy chain comprising the amino acid sequence of SEQ ID NO: 179 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; (h) a heavy chain comprising the amino acid sequence of SEQ ID NO: 200 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; (i) a heavy chain comprising the amino acid sequence of SEQ ID NO: 180 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; (j) a heavy chain comprising the amino acid sequence of SEQ ID NO: 201 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; (k) a heavy chain comprising the amino acid sequence of SEQ ID NO: 181 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; (l) a heavy chain comprising the amino acid sequence of SEQ ID NO: 202 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; (m) a heavy chain comprising the amino acid sequence of SEQ ID NO: 182 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; (n) a heavy chain comprising the amino acid sequence of SEQ ID NO: 203 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; (o) a heavy chain comprising the amino acid sequence of SEQ ID NO: 183 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; (p) a heavy chain comprising the amino acid sequence of SEQ ID NO: 204 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; (q) a heavy chain comprising the amino acid sequence of SEQ ID NO: 184 and a light chain comprising the amino acid sequence of SEQ ID NO: 185; or (r) the antibody, comprising a heavy chain comprising the amino acid sequence of SEQ ID NO: 205 and a light chain comprising the amino acid sequence of SEQ ID NO:

185.

55. An isolated nucleic acid comprising a nucleic acid sequence encoding the antibody of any one of claims 1 to 54.

56. A vector comprising the nucleic acid of claim 55.

57. 57. An isolated host cell comprising the vector of claim 56.

58. 58. A method for producing an antibody that binds to CD33, comprising culturing the cells of claim 57 so that the antibody is produced.

59. 59. The method of claim 58, further comprising recovering the antibody produced by the cell.

60. 60. An isolated antibody that binds to CD33 produced by the method of claim 58 or claim 59.

61. A pharmaceutical composition comprising the antibody of any one of claims 1 to 54 and a pharmaceutically acceptable carrier.

62. 55. A method for preventing, reducing the risk of, or treating a disease, disorder, or injury selected from the group consisting of dementia, frontotemporal dementia, Alzheimer's disease, vascular dementia, mixed dementia, taupathies, infectious diseases, and cancer, comprising administering to an individual in need thereof a therapeutically effective amount of the antibody of any one of claims 1 to 54.

63. 63. The method of claim 62, wherein the disease, disorder, or injury is cancer.

64. 64. The method of claim 62 or claim 63, wherein the cancer is selected from the group consisting of bladder cancer, brain cancer, breast cancer, colon cancer, rectal cancer, endometrial cancer, kidney cancer, renal cell carcinoma, renal pelvis cancer, leukemia, lung cancer, melanoma, non-Hodgkin's lymphoma, pancreatic cancer, prostate cancer, ovarian cancer, fibrosarcoma, acute lymphocytic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), chronic myelogenous leukemia (CML), and multiple myeloma.

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