Engineered iga antibodies and methods of use thereof

Abstract

Provided herein are engineered antibodies comprising modified IgA heavy chain constant regions, pharmaceutical compositions, and methods of use. The engineered antibodies described herein comprise one or more amino acid substitutions or deletions in the constant region of an IgA domain. Also provided herein are methods of treating disorders, including cancer, by administering the engineered IgA antibodies described herein.

Description

[0001] Cross-references

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 824,864, filed March 27, 2019, which is incorporated herein by reference in its entirety.

[0003] Background of this public disclosure

[0004] IgG isotype monoclonal antibodies targeting tumor antigens have proven effective in treating various cancers. Over the years, an increasing number of monoclonal antibodies targeting different tumor antigens have been approved for cancer treatment. However, their clinical efficacy and side effects, particularly as monotherapy, remain inadequate. Therefore, it is of interest to develop novel antibody therapies with increased clinical efficacy, novel targeting mechanisms or modes of action, and / or reduced number and severity of side effects.

[0005] Overview of this public disclosure

[0006] This article provides an antibody or a functional fragment thereof, the antibody or functional fragment thereof comprising: an antigen-binding domain; and a constant domain, wherein the constant domain comprises an immunoglobulin A (IgA) heavy chain constant region, wherein the IgA heavy chain constant region comprises an IgA CH2 region and an IgA CH3 region, wherein the IgA heavy chain constant region comprises modifications of at least two naturally occurring glycosylation sites compared to the corresponding wild-type (WT) IgA heavy chain constant region, and wherein each of the at least two naturally occurring glycosylation sites is located in the IgA CH2 region or the IgA CH3 region.

[0007] In some embodiments, the at least two naturally occurring glycosylation sites are two naturally occurring N-linked glycosylation sites. In some embodiments, one or more of the at least two naturally occurring glycosylation sites in the engineered antibodies disclosed herein comprises a modified naturally occurring asparagine (N) amino acid residue compared to the corresponding wild type IgA. In some embodiments, the modification comprises an amino acid substitution or an amino acid deletion of one or both of the at least two naturally occurring glycosylation sites. In some embodiments, the amino acid substitution is a non-conservative amino acid substitution. In some embodiments, the IgA heavy chain constant region comprises an amino acid substitution at i. N114 and N135, ii. N114 and N15.2, or iii. N135 and N15.2, according to IMGT numbering scheme, relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1. In some embodiments, the IgA heavy chain constant region comprises i. a N114T amino acid substitution and a N135Q amino acid substitution, ii. a N114T amino acid substitution and an amino acid substitution from the group consisting of N15.2G, N15.2Q, and N15.2T, or iii. a N135Q amino acid substitution and an amino acid substitution from the group consisting of N15.2G, N15.2Q, and N15.2T, according to IMGT numbering scheme, relative to the corresponding WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1.

[0008] In some embodiments, the IgA heavy chain constant region comprises a modification of at least three naturally occurring glycosylation sites compared to the corresponding wild type IgA. In some embodiments, the at least three naturally occurring glycosylation sites are three N-linked glycosylation sites. In some embodiments, each of the three naturally occurring glycosylation sites in the antibodies described herein comprises a modified asparagine (N) amino acid residue.

[0009] In some embodiments, the modification is an amino acid substitution or an amino acid deletion. In some embodiments, the amino acid substitution is a non-conservative substitution. In some embodiments, the IgA heavy chain constant region comprises an amino acid substitution at N114, N135, and N15.2, according to IMGT numbering scheme, relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1. In some embodiments, the IgA heavy chain constant region comprises i. a N114T amino acid substitution, ii. a N135Q amino acid substitution, and iii. an amino acid substitution from the group consisting of N15.2G, N15.2Q, and N15.2T, according to IMGT numbering scheme, relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1.

[0010] In some embodiments, the IgA heavy chain constant region of the antibodies described herein further comprises an IgA CH1 region. In some embodiments, the heavy chain constant region comprises, as compared to the corresponding wild type IgA: a modification of at least one naturally occurring N-linked glycosylation site in the IgA CH2 region, a modification of at least one naturally occurring glycosylation site in the IgA CH3 region, and a modification of at least one naturally occurring glycosylation site within the IgA CH1 region. In some embodiments, the IgA heavy chain constant region comprises amino acid substitutions at i. N45.2, N114, and N135, or ii. N45.2, N15.2, and N135, according to IMGT scheme numbering, relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1.

[0011] In some embodiments, the IgA heavy chain constant region comprises, relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1: i. a N45.2G amino acid substitution, a N114T amino acid substitution, and a N135Q amino acid substitution; or ii. a N45.2G amino acid substitution, a N135Q amino acid substitution, and an amino acid substitution selected from the group consisting of N15.2G, N15.2Q, and N15.2T, according to IMGT scheme numbering.

[0012] In some embodiments, the heavy chain constant region of the antibodies described herein comprises, as compared to the corresponding wild type IgA: a modification of at least two naturally occurring N-linked glycosylation sites in the IgA CH2 region, and a modification of at least one naturally occurring glycosylation site within the IgA CH1 region. In some embodiments, the IgA heavy chain constant region comprises amino acid substitutions at i. N45.2, N114, and N15.2G, according to IMGT scheme numbering. In some embodiments, the IgA heavy chain constant region described herein comprises, relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1: i. a N45.2G amino acid substitution, ii. a N114T amino acid substitution, and iii. an amino acid substitution selected from the group consisting of N15.2G, N15.2Q, and N15.2T, according to IMGT scheme numbering.

[0013] In some embodiments, the antibodies or functional fragments thereof described herein exhibit a longer circulating half-life compared to a corresponding WT IgA antibody. In some embodiments, the antibodies or functional fragments thereof exhibit reduced aggregation compared to a corresponding WT IgA antibody. In some embodiments, the antibodies or functional fragments thereof exhibit reduced aggregation with serum proteins compared to a corresponding WT IgA antibody. In some embodiments, the antibodies or functional fragments thereof induce increased antibody-dependent cell-mediated cytotoxicity (ADCC) compared to a comparable antibody comprising an IgG heavy chain constant region. In some embodiments, the antibodies or functional fragments thereof exhibit increased thermal stability compared to a corresponding WT IgA antibody. In some embodiments, the antibodies or functional fragments thereof exhibit reduced glycosylation compared to a corresponding WT IgA antibody.

[0014] In some embodiments, the IgA heavy chain constant region exhibits binding to FcaR expressed on immune effector cells with increased affinity compared to a corresponding WT IgA antibody. In some embodiments, the IgA heavy chain constant region comprises modification of at least four naturally occurring glycosylation sites compared to a corresponding wild-type IgA. In some embodiments, the at least four naturally occurring glycosylation sites are four naturally occurring N-linked glycosylation sites. In some embodiments, the at least four naturally occurring glycosylation sites each comprise a naturally occurring asparagine (N) amino acid residue. In some embodiments, the heavy chain constant region comprises, compared to a corresponding wild-type IgA, modification of at least two naturally occurring N-linked glycosylation sites within the IgA CH2 region, modification of at least one naturally occurring N-linked glycosylation site within the IgA CH3 region, and modification of at least one naturally occurring N-linked glycosylation site within the IgA CHI region. In some embodiments, the IgA heavy chain constant region comprises amino acid substitutions at the following amino acid residues: N45.2, N114, N135, and N15.2, numbered according to the IMGT scheme.

[0015] In some embodiments, the IgA heavy chain constant region of the antibodies described herein comprises non-conservative amino acid substitutions at the following amino acid residues: N45.2, N114, N135, and N15.2, numbered according to the IMGT scheme.

[0016] In some embodiments, the IgA heavy chain constant region comprises, relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1 : i. a N45.2G amino acid substitution, ii. a N114T amino acid substitution, iii. a N135Q amino acid substitution, and iv. an amino acid substitution selected from the group consisting of N15.2G, N15.2Q, and N15.2T, numbering according to the IMGT scheme. In some embodiments, the antibody or functional fragment thereof exhibits a longer circulating half-life compared to a corresponding IgA antibody comprising at least one naturally occurring N-linked glycosylation site. In some embodiments, the antibody or functional fragment thereof induces increased antibody-dependent cell-mediated cytotoxicity (ADCC) compared to a corresponding comparable antibody comprising an IgG CH2 domain and an IgG CH3 domain. In some embodiments, the antibody or functional fragment thereof exhibits increased thermal stability compared to a corresponding IgA antibody comprising at least one naturally occurring N-linked glycosylation site. In some embodiments, the antibody or functional fragment thereof exhibits reduced glycosylation compared to a corresponding IgA antibody comprising at least one naturally occurring N-linked glycosylation site. In some embodiments, the IgA heavy chain constant region exhibits binding to FcaR expressed on immune effector cells with increased affinity compared to a corresponding IgA antibody comprising at least one naturally occurring N-linked glycosylation site.

[0017] In some embodiments, the IgA heavy chain constant region of the antibodies described herein comprises a modification of at least one naturally occurring cysteine (C) amino acid residue compared to a corresponding wild-type IgA. In some embodiments, the modification is an amino acid substitution or an amino acid deletion of the at least one naturally occurring cysteine (C) amino acid residue. In some embodiments, the amino acid substitution is a non-conservative amino acid substitution of the at least one naturally occurring cysteine (C) amino acid residue. In some embodiments, the at least one naturally occurring cysteine amino acid residue is C147 or C86 relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises a C86S amino acid substitution relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises a deletion of C147 relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the antibody or functional fragment thereof exhibits reduced aggregation compared to a corresponding WT IgA antibody or functional fragment thereof. In some embodiments, the antibody or functional fragment thereof exhibits reduced aggregation with serum proteins compared to a corresponding WT IgA construct.

[0018] In some embodiments, the IgA heavy chain constant region of the antibodies described herein comprises a modification of at least two naturally occurring cysteine (C) amino acid residues compared to a corresponding wild type IgA. In some embodiments, the modification comprises an amino acid substitution of one or both of the at least two naturally occurring cysteine (C) amino acid residues. In some embodiments, the modification comprises a deletion of one or both of the at least two naturally occurring cysteine (C) amino acid residues.

[0019] In some embodiments, the IgA heavy chain constant region comprises an amino acid substitution of one of the at least two naturally occurring cysteine (C) amino acid residues, and a deletion of one of the at least two naturally occurring cysteine (C) amino acid residues. In some embodiments, the at least two naturally occurring cysteine amino acid residues are C147 and C86 relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises a deletion of C147 relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises an amino acid substitution of C86 relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme.

[0020] In some embodiments, the IgA heavy chain constant region of the antibodies described herein comprises an amino acid substitution of the naturally occurring C86 amino acid residue and a deletion of the naturally occurring C147 amino acid residue relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises a C86S amino acid substitution relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the antibody or functional fragment thereof exhibits reduced aggregation compared to a corresponding WT IgA antibody. In some embodiments, the antibody or functional fragment thereof exhibits reduced aggregation with serum proteins compared to a corresponding WT IgA antibody.

[0021] In some embodiments, the IgA heavy chain constant region of the antibodies described herein comprises at least one modification of a naturally occurring tyrosine (Y) amino acid residue compared to the corresponding wild type IgA. In some embodiments, the modification is an amino acid substitution or deletion of at least one naturally occurring tyrosine (Y) amino acid residue. In some embodiments, the amino acid substitution is a non-conservative amino acid mutation of at least one naturally occurring tyrosine (Y) amino acid residue compared to the WT IgA antibody. In some embodiments, the at least one tyrosine residue is Y148 relative to the WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the amino acid Y148 is deleted relative to the WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the antibody or functional fragment thereof exhibits reduced aggregation compared to the corresponding WT IgA antibody. In some embodiments, the antibody or functional fragment thereof exhibits reduced aggregation with serum proteins compared to the corresponding WT IgA antibody.

[0022] In some embodiments, the IgA heavy chain constant region of the antibodies described herein comprises at least one modification of a naturally occurring threonine (T) amino acid residue compared to a corresponding wild type IgA antibody. In some embodiments, the modification comprises an amino acid substitution or deletion of at least one naturally occurring threonine (T) amino acid residue compared to a corresponding wild type IgA antibody. In some embodiments, the amino acid substitution is a non-conservative amino acid substitution of at least one naturally occurring threonine (T) amino acid residue. In some embodiments, the at least one naturally occurring threonine amino acid residue is T116 or T16 relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the antibody or functional fragment thereof exhibits reduced aggregation compared to a corresponding WT IgA antibody. In some embodiments, the antibody or functional fragment thereof exhibits reduced aggregation with serum proteins compared to a corresponding WT IgA antibody. In some embodiments, the IgA heavy chain constant region comprises at least two modifications of a naturally occurring threonine (T) amino acid residue compared to a corresponding wild type IgA antibody. In some embodiments, the modification comprises an amino acid substitution or deletion of one or both of the at least two naturally occurring threonine (T) amino acid residues. In some embodiments, the amino acid substitution is a non-conservative amino acid substitution of one or both of the at least two naturally occurring threonine (T) amino acid residues. In some embodiments, the at least two naturally occurring threonine (T) amino acid residues are T116 or T16 relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises a T116S amino acid substitution relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises a T16S amino acid substitution relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme.

[0023] In some embodiments, the IgA heavy chain constant region of the antibodies described herein comprises at least one modification of a naturally occurring isoleucine (I) amino acid residue compared to the corresponding wild type IgA. In some embodiments, the modification comprises an amino acid substitution or deletion of at least one naturally occurring isoleucine (I) amino acid residue. In some embodiments, the amino acid substitution comprises a non-conservative amino acid substitution of at least one naturally occurring isoleucine (I) amino acid residue. In some embodiments, the at least one naturally occurring isoleucine (I) residue is I115 relative to the WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises an I115L amino acid substitution relative to the WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises at least one modification of a naturally occurring leucine (L) amino acid residue compared to the corresponding wild type IgA antibody. In some embodiments, the modification comprises an amino acid substitution or deletion of at least one naturally occurring leucine (L) amino acid residue. In some embodiments, the amino acid substitution is a non-conservative amino acid substitution of at least one naturally occurring leucine (L) amino acid residue. In some embodiments, the at least one naturally occurring leucine (L) residue is L15.3 relative to the WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises an L15.3I amino acid substitution relative to the WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme.

[0024] In some embodiments, the IgA heavy chain constant region of the antibodies described herein comprises a modification of at least one naturally occurring proline (P) amino acid residue compared to a corresponding wild type IgA. In some embodiments, the IgA heavy chain constant region comprises an amino acid substitution or deletion of at least one naturally occurring proline (P) amino acid residue. In some embodiments, the amino acid substitution is a non-conservative amino acid substitution of at least one naturally occurring proline (P) amino acid residue. In some embodiments, the at least one naturally occurring proline (P) residue is P124 with respect to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises a P124R amino acid substitution with respect to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the antibody or functional fragment thereof exhibits greater stability compared to a corresponding WT IgA antibody. In some embodiments, the antibody or functional fragment thereof exhibits greater stability between the heavy chain and the light chain compared to a corresponding WT IgA antibody. In some embodiments, the antibody or functional fragment thereof has a covalent linkage between the heavy chain and the light chain. In some embodiments, the antibody or functional fragment thereof comprises a disulfide bond between a cysteine (C) amino acid residue of the heavy chain and a cysteine (C) amino acid residue of the light chain. In some embodiments, the IgA heavy chain constant region comprises an amino acid sequence selected from any one of SEQ ID NOs: 16-21.

[0025] In some embodiments, the antibodies described herein comprise a heavy chain region of a modified IgA of allotype IgA2m(l) antibody or IgA2m(2). In some embodiments, the antibody is an allotype Caucasian IgA2m(l) antibody. In some embodiments, the IgA heavy chain constant region comprises a modification of the C-terminal IgA tail piece compared to a corresponding wild type IgA. In some embodiments, the modification comprises a deletion of C-terminal 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 12, 10, 8, 6, 4, or 2 amino acids. In some embodiments, the modification comprises a deletion of C-terminal 18 amino acids. In some embodiments, the modification comprises a deletion of C-terminal amino acid residues 131-148 with respect to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises a deletion of C-terminal amino acid residues P131-Y148 with respect to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbering according to the IMGT scheme.

[0026] In some embodiments, the IgA heavy chain constant region of the antibody described herein comprises an IgAl constant region comprising an IgAl CH2 region and an IgAl CH3 region. In some embodiments, the IgAl constant region further comprises an IgAl CH1 region. In some embodiments, the IgA heavy chain constant region comprises an IgA2 constant region comprising an IgA2 CH2 region and an IgA2 CH3 region. In some embodiments, the IgA2 constant region further comprises an IgA2 CH1 region. In some embodiments, the antibody or functional fragment thereof exhibits a circulating half-life that is within 1%, 5%, 10%, 20%, or 30% of the circulating half-life of a corresponding antibody comprising an antigen binding domain and an IgA heavy chain constant region comprising an IgG CH2 region and an IgG CH3 region.

[0027] Provided herein is an antibody or functional fragment thereof, comprising: an antigen binding domain; and a constant domain, wherein the constant domain comprises an IgA2 heavy chain constant region comprising an IgA2 CH1 region, an IgA2 CH2 region, and an IgA2 CH3 region; wherein the IgA2 heavy chain constant region comprises an N135Q amino acid substitution relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbered according to the IMGT scheme.

[0028] In some embodiments, the heavy chain constant region further comprises, relative to a WT IgA2 heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, the following: an N45.2G amino acid substitution, an N114T amino acid substitution, an I115L amino acid substitution, a T116S amino acid substitution, and an amino acid substitution selected from the group consisting of N15.2G, N15.2Q, and N15.2T, numbered according to the IMGT scheme. In some embodiments, the heavy chain constant region further comprises, relative to a WT IgA2 heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, the following: a C86S amino acid substitution, a P124R amino acid substitution, a deletion of C147, a deletion of Y148, a L15.3I amino acid substitution, a T16S amino acid substitution, or a combination thereof, numbered according to the IMGT scheme.

[0029] Provided herein is an antibody or functional fragment thereof, comprising: an antigen binding domain; and a constant domain, wherein the constant domain comprises an IgA2 heavy chain constant region comprising an IgA2 CH2 region and an IgA2 CH3 region, and wherein the IgA2 heavy chain constant region comprises the following relative to a WT IgA2 heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1 : a C86S amino acid substitution, a N114T amino acid substitution, a I115L amino acid substitution, a T116S amino acid substitution, and a N135Q amino acid substitution, numbered according to the IMGT scheme.

[0030] Provided herein is an antibody or functional fragment thereof, comprising: an antigen binding domain; and a constant domain, wherein the constant domain comprises an IgA2 heavy chain constant region comprising an IgA2 CH1 region, an IgA2 CH2 region, and an IgA CH3 region, and wherein the IgA2 heavy chain constant region comprises the following relative to a WT IgA2 heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1 : a N45.2G amino acid substitution, a C86S amino acid substitution, a N114T amino acid substitution, a I115L amino acid substitution, a T116S amino acid substitution, a N135Q amino acid substitution, a deletion of C147, and a deletion of Y148, numbered according to the IMGT scheme. In some embodiments, the IgA2 heavy chain constant region comprises an amino acid sequence that is at least 95% identical to SEQ ID NO: 16.

[0031] Provided herein is an antibody or functional fragment thereof, comprising: an antigen binding domain; and a constant domain, wherein the constant domain comprises an IgA2 heavy chain constant region comprising an IgA2 CH1 region, an IgA2 CH2 region, and an IgA2 CH3 region, and wherein the IgA2 heavy chain constant region comprises the following relative to a WT IgA2 heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1 : a N45.2G amino acid substitution, a C86S amino acid substitution, a N114T amino acid substitution, a I115L amino acid substitution, a T116S amino acid substitution, and a deletion of a C-terminal tail, numbered according to the IMGT scheme.

[0032] In some embodiments, the deletion of the C-terminal tail comprises a deletion of C-terminal amino acid residues P131-Y148 relative to a WT IgA heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1, numbered according to the IMGT scheme.

[0033] In some embodiments, the IgA2 heavy chain constant region of the antibody described herein comprises an amino acid sequence that is at least 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, or 100% identical to SEQ ID NO: 17.

[0034] Provided herein is an antibody or functional fragment thereof, comprising: an antigen binding domain; and a constant domain, wherein the constant domain comprises an IgA2 heavy chain constant region comprising an IgA2 CH1 region, an IgA2 CH2 region, and an IgA2 CH3 region; wherein the IgA2 heavy chain constant region comprises, relative to a WT IgA2 heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1: an N45.2G amino acid substitution, an N114T amino acid substitution, an I115L amino acid substitution, a T116S amino acid substitution, an N135Q amino acid substitution, an amino acid substitution selected from the group consisting of N15.2G, N15.2Q, and N15.2T, an L15.3I amino acid substitution, and a T16S amino acid substitution, numbered according to the IMGT scheme.

[0035] Provided herein is an antibody or functional fragment thereof, comprising: an antigen binding domain; and a constant domain, wherein the constant domain comprises an IgA2 heavy chain constant region comprising an IgA2 CH1 region, an IgA2 CH2 region, and an IgA2 CH3 region, and wherein the IgA2 heavy chain constant region comprises, relative to a WT IgA2 heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1: an N45.2G amino acid substitution, an N114T amino acid substitution, an I115L amino acid substitution, a T116S amino acid substitution, an amino acid substitution selected from the group consisting of N15.2G, N15.2Q, and N15.2T, an L15.3I amino acid substitution, a T16S amino acid substitution, and a deletion of C-terminal amino acids P131-Y148, numbered according to the IMGT scheme.

[0036] In some embodiments, the antibody or functional fragment thereof disclosed herein comprises, relative to the WT IgA2 heavy chain constant region comprising the amino acid sequence of SEQ ID NO:1, a C86S amino acid substitution, a P124R amino acid substitution, a deletion of C147, a deletion of Y148, or a combination thereof, according to IMGT scheme numbering. In some embodiments, the IgA2 heavy chain constant region comprises an amino acid sequence that is at least 95% identical to the sequence selected from any one of SEQ ID NO:18-21. In some embodiments, the antibody or functional fragment thereof is non-glycosylated. In some embodiments, the antibody or functional fragment thereof has an increased cycling half-life compared to the corresponding IgA comprising one or more of wild-type amino acid residues N45.2, N114, I115, T116, N15.2, L15.3, T16, or C-terminal amino acid residues P131-Y148, according to IMGT scheme numbering.

[0037] In some embodiments, the antibody or functional fragment thereof described herein induces increased antibody-dependent cell-mediated cytotoxicity (ADCC) compared to a corresponding antibody comprising an IgG heavy chain constant domain. In some embodiments, the antibody or functional fragment thereof exhibits increased thermal stability compared to a corresponding IgA comprising one or more of wild-type amino acid residues N45.2, N114, 1115, T116, N15.2, L15.3, T16, or C-terminal amino acid residues P131-Y148, numbered according to the IMGT scheme. In some embodiments, the antibody or functional fragment thereof exhibits decreased glycosylation compared to a corresponding IgA comprising one or more of wild-type amino acid residues N45.2, N114, 1115, T116, N15.2, L15.3, T16, or C-terminal amino acid residues P131-Y148, numbered according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region exhibits increased affinity for binding to FcaR expressed on immune effector cells compared to a corresponding IgA comprising one or more of wild-type amino acid residues N45.2, N114, 1115, T116, N15.2, L15.3, T16, or C-terminal amino acid residues P131-Y148, numbered according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region further comprises a hinge region. In some embodiments, the hinge region comprises an IgA hinge amino acid sequence or a variant or fragment thereof. In some embodiments, the hinge region comprises a human IgA hinge amino acid sequence or a variant or fragment thereof. In some embodiments, the hinge is an IgAl hinge or an IgA2 hinge or a variant or fragment thereof. In some embodiments, the constant domain further comprises a light chain constant region. In some embodiments, the light chain constant region is a kappa light chain constant region, wherein the kappa light chain constant region comprises the sequence of SEQ ID NO: 31. In some embodiments, the IgA heavy chain constant region further comprises one or more albumin binding regions. In some embodiments, the one or more albumin binding domains are fused to the C-terminus of the CH3 region. In some embodiments, the constant region comprises a light chain constant region, and the one or more albumin binding domains are fused to the light chain constant region. In some embodiments, the antibody or functional fragment thereof has a longer circulating half-life compared to a corresponding IgA antibody that does not comprise the one or more albumin binding domains. In some embodiments, the antibody or functional fragment thereof exhibits decreased complement-dependent cytotoxicity (CDC) compared to a corresponding antibody comprising an IgG heavy chain constant domain when measured in a suitable in vitro CDC assay.

[0038] In some embodiments, the antibodies or functional fragments thereof described herein exhibit increased antibody-dependent cell-mediated cytotoxicity (ADCC) when measured in a suitable in vitro ADCC assay as compared to a corresponding WT IgA antibody. In some embodiments, the antigen binding domain comprises a heavy chain variable region and a light chain variable region. In some embodiments, the heavy chain variable region of the antibodies described herein comprises at least one of the following complementarity determining regions (CDRs): HC-CDR1 comprising an amino acid sequence selected from any one of SEQ ID NOs: 33-40, HC-CDR2 comprising an amino acid sequence selected from any one of SEQ ID NOs: 41-48; and HC-CDR3 comprising an amino acid sequence selected from any one of SEQ ID NOs: 49-56.

[0039] In some embodiments, the light chain variable region of the antibodies described herein comprises at least one of the following complementarity determining regions (CDRs): LC-CDR1 comprising an amino acid sequence selected from any one of SEQ ID NOs: 57-64; LC-CDR2 comprising an amino acid sequence selected from any one of SEQ ID NOs: 65-72; and LC-CDR3 comprising an amino acid sequence selected from any one of SEQ ID NOs: 73-80.

[0040] In some embodiments, the heavy chain variable region of the described antibodies comprises a sequence that is at least 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, or 100% identical to an amino acid sequence selected from any one of SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NOs: 81-86. In some embodiments, the light chain variable region comprises a sequence that is at least 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, or 100% identical to an amino acid sequence selected from any one of SEQ ID NO: 5, SEQ ID NO: 8, SEQ ID NOs: 95-100. In some embodiments, each of the heavy chain CDRs and the light chain CDRs are derived from an IgG antibody. In some embodiments, the heavy chain variable region further comprises the following four framework regions (FWs): HC-FW1, HC-FW2, HC-FW3, and HC-FW4. In some embodiments, the light chain variable region further comprises the following four framework regions (FWs): LC-FW1, LC-FW2, LC-FW3, and LC-FW4.

[0041] In some embodiments, each of the heavy and light chain FW regions is derived from an IgG antibody. In some embodiments, each of the heavy and light chain FW regions is derived from an IgA antibody.

[0042] In some embodiments, the antibody or functional fragment thereof described herein is a chimeric antibody, a heavy chain antibody, a single chain antibody, a humanized antibody, a human antibody, a monoclonal antibody, a de-immunized antibody, a bispecific antibody, a multispecific antibody, a multivalent antibody, or a combination thereof.

[0043] In some embodiments, the antigen binding fragment of the antibody described herein includes a Fab, Fab', Fab'-SH, Fv, scFv, F(ab')2, diabody, linear antibody, single domain antibody (sdAb), VHH domain, or a multispecific antibody formed from antibody fragments. In some embodiments, the variable domain specifically binds to GD2, CD20, CD47, CD38, CD19, EGFR, HER2, PD-L1, or CD25. In some embodiments, the antibody or functional fragment thereof further includes an enzyme, a substrate, a cofactor, a luminescent marker, a chemiluminescent marker, a peptide tag, a magnetic particle, a drug, a toxin, a radionuclide, a binding site for a secondary antibody, a metal binding domain, or a combination thereof.

[0044] Provided herein is a pharmaceutical composition comprising the antibody or functional fragment thereof of any of the above aspects and a pharmaceutically acceptable carrier.

[0045] Provided herein is a method for treating or a composition for use in treating a subject in need thereof, comprising administering to the subject a therapeutic dose of the antibody or functional fragment thereof of any of the above aspects or the pharmaceutical composition disclosed above.

[0046] In some embodiments, the antibody or functional fragment thereof or the pharmaceutical composition is cytolytic to a target cell. In some embodiments, the target cell is a cancer cell. In some embodiments, the antibody or functional fragment thereof or the pharmaceutical composition inhibits tumor growth. In some embodiments, the antibody or functional fragment thereof or the pharmaceutical composition is administered subcutaneously, intravenously, intradermally, intraperitoneally, orally, intramuscularly, or intracranially. In some embodiments, the antibody or functional fragment thereof or the pharmaceutical composition is administered to the subject in combination with a second therapeutic agent. In some embodiments, the second therapeutic agent includes an anti-cancer agent, a chemotherapeutic agent, radiation therapy, a cytotoxic agent, an NSAID, a corticosteroid, a dietary supplement such as an antioxidant, or a combination thereof. In some embodiments, the second therapeutic agent is administered prior to, concurrently with, or after administration of the antibody or functional fragment thereof or the pharmaceutical composition.

[0047] Provided herein is an isolated nucleic acid encoding the antibody or functional fragment thereof of any of the above aspects.

[0048] Provided herein is an isolated nucleic acid molecule encoding a heavy chain polypeptide, the isolated nucleic acid molecule comprising a first nucleic acid sequence encoding an IgA heavy chain constant region, wherein the first nucleic acid sequence is selected from any one of SEQ ID NOs: 25-32. In some embodiments, the isolated nucleic acid molecule of the above aspect further comprises a second nucleic acid sequence encoding a heavy chain variable region, wherein the second nucleic acid sequence is selected from any one of SEQ ID NOs: 87-94.

[0049] Provided herein is a vector comprising the isolated nucleic acid molecule of any of the above aspects.

[0050] Provided herein is a host cell comprising the isolated nucleic acid molecule of any of the above aspects. In some embodiments, the host cell of any of the above aspects further comprises an isolated nucleic acid molecule encoding a light chain polypeptide, wherein the isolated nucleic acid molecule encoding a light chain polypeptide comprises a nucleic acid sequence encoding a light chain variable region, wherein the nucleic acid sequence is selected from any one of SEQ ID NOs: 101-108. In some embodiments, the isolated nucleic acid molecule encoding a light chain polypeptide further comprises a nucleic acid sequence encoding a kappa light chain constant region, wherein the nucleic acid sequence comprises the sequence of SEQ ID NO: 32.

[0051] Provided herein is a host cell expressing the antibody or functional fragment thereof of any of the above aspects. In some embodiments, the host cell is a bacterial cell or a mammalian cell. In some embodiments, the host cell is a CHO cell or a HEK293 cell.

[0052] Provided herein is a method of producing an antibody or functional fragment thereof, the method comprising: (a) culturing the host cell of any of the above aspects in a culture medium under conditions that allow for expression of the polypeptide encoded by the isolated nucleic acid molecule and assembly of the antibody or functional fragment thereof; and (b) purifying the antibody or functional fragment thereof from the cultured host cell or culture medium of the host cell. In some embodiments, the purification is by size exclusion chromatography.

[0053] Provided herein is an antibody or functional fragment thereof that selectively binds to a CD20 polypeptide or variant thereof, the antibody or functional fragment thereof comprising: (a) an IgA heavy chain constant region, wherein the IgA heavy chain constant region comprises an amino acid sequence selected from any one of SEQ ID NOs: 16-21; and (b) a heavy chain variable region, wherein the heavy chain variable region comprises at least one of: a heavy chain complementarity determining region 1 (HC-CDR1) of SEQ ID NO: 33, a HC-CDR2 of SEQ ID NO: 41, and a HC-CDR3 of SEQ ID NO: 49; (c) a light chain variable region, wherein the light chain variable region comprises at least one of: a light chain complementarity determining region 1 (LC-CDR1) of SEQ ID NO: 57, a LC-CDR2 of SEQ ID NO: 65, and a LC-CDR3 of SEQ ID NO: 73; or (d) a variable heavy chain of (b) and a variable light chain of (c). In some embodiments, the variable heavy chain comprises a polypeptide sequence having at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 81, and the variable light chain comprises a polypeptide sequence having at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 95.

[0054] Provided herein is an antibody or functional fragment thereof that selectively binds to a GD2 protein or variant thereof, the antibody or functional fragment thereof comprising: (a) an IgA heavy chain constant region, wherein the IgA heavy chain constant region comprises an amino acid sequence selected from any one of SEQ ID NOs: 16-21; and (b) a heavy chain variable region, wherein the heavy chain variable region comprises at least one of: a heavy chain complementarity determining region 1 (HC-CDR1) of SEQ ID NO: 34, a HC-CDR2 of SEQ ID NO: 42, and a HC-CDR3 of SEQ ID NO: 50; (c) a light chain variable region, wherein the light chain variable region comprises at least one of: a light chain complementarity determining region 1 (LC-CDR1) of SEQ ID NO: 58, a LC-CDR2 of SEQ ID NO: 66, and a LC-CDR3 of SEQ ID NO: 74; or (d) a variable heavy chain of (b) and a variable light chain of (c). In some embodiments, the variable heavy chain comprises a polypeptide sequence having at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 4, and the variable light chain comprises a polypeptide sequence having at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 5.

[0055] Provided herein is an antibody or functional fragment thereof that selectively binds to a Her2 protein or variant thereof, the antibody or functional fragment thereof comprising: (a) an IgA heavy chain constant region, wherein the IgA heavy chain constant region comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 16-21; and (b) a heavy chain variable region, wherein the heavy chain variable region comprises at least one of: a heavy chain complementarity determining region 1 (HC-CDR1) of SEQ ID NO: 35, a HC-CDR2 of SEQ ID NO: 43, and a HC-CDR3 of SEQ ID NO: 51; (c) a light chain variable region, wherein the light chain variable region comprises at least one of: a light chain complementarity determining region 1 (LC-CDR1) of SEQ ID NO: 59, a LC-CDR2 of SEQ ID NO: 67, and a LC-CDR3 of SEQ ID NO: 75; or (d) a variable heavy chain of (b) and a variable light chain of (c). In some embodiments, the variable heavy chain comprises a polypeptide sequence having at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 82, and the variable light chain comprises a polypeptide sequence having at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 96.

[0056] Provided herein is an antibody or functional fragment thereof that selectively binds to a gp75 protein or variant thereof, the antibody or functional fragment thereof comprising: (a) an IgA heavy chain constant region, wherein the IgA heavy chain constant region comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 16-21; and (b) a heavy chain variable region, wherein the heavy chain variable region comprises at least one of: a heavy chain complementarity determining region 1 (HC-CDR1) of SEQ ID NO: 36, a HC-CDR2 of SEQ ID NO: 44, and a HC-CDR3 of SEQ ID NO: 52; (c) a light chain variable region, wherein the light chain variable region comprises at least one of: a light chain complementarity determining region 1 (LC-CDR1) of SEQ ID NO: 60, a LC-CDR2 of SEQ ID NO: 68, and a LC-CDR3 of SEQ ID NO: 76; or (d) a variable heavy chain of (b) and a variable light chain of (c). In some embodiments, the variable heavy chain comprises a polypeptide sequence having at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 83, and the variable light chain comprises a polypeptide sequence having at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 97.

[0057] Provided herein is an antibody or functional fragment thereof that selectively binds to a CTLA4 protein or variant thereof, the antibody or functional fragment thereof comprising: (a) an IgA heavy chain constant region, wherein the IgA heavy chain constant region comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 16-21; and (b) a heavy chain variable region, wherein the heavy chain variable region comprises at least one of: a heavy chain complementarity determining region 1 (HC-CDR1) of SEQ ID NO: 37, a HC-CDR2 of SEQ ID NO: 45, and a HC-CDR3 of SEQ ID NO: 53; (c) a light chain variable region, wherein the light chain variable region comprises at least one of: a light chain complementarity determining region 1 (LC-CDR1) of SEQ ID NO: 61, a LC-CDR2 of SEQ ID NO: 69, and a LC-CDR3 of SEQ ID NO: 77; or (d) a variable heavy chain of (b) and a variable light chain of (c). In some embodiments, the variable heavy chain comprises a polypeptide sequence having at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 84, and the variable light chain comprises a polypeptide sequence having at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 98.

[0058] Provided herein is an antibody or functional fragment thereof that selectively binds to a CD47 protein or variant thereof, the antibody or functional fragment thereof comprising: (a) an IgA heavy chain constant region, wherein the IgA heavy chain constant region comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 16-21; and (b) a heavy chain variable region, wherein the heavy chain variable region comprises at least one of: a heavy chain complementarity determining region 1 (HC-CDR1) of SEQ ID NO: 38, a HC-CDR2 of SEQ ID NO: 46, and a HC-CDR3 of SEQ ID NO: 54; (c) a light chain variable region, wherein the light chain variable region comprises at least one of: a light chain complementarity determining region 1 (LC-CDR1) of SEQ ID NO: 62, a LC-CDR2 of SEQ ID NO: 70, and a LC-CDR3 of SEQ ID NO: 78; or (d) a variable heavy chain of (b) and a variable light chain of (c). In some embodiments, the variable heavy chain comprises a polypeptide sequence having at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 85, and the variable light chain comprises a polypeptide sequence having at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 99.

[0059] Provided herein is an antibody or functional fragment thereof, comprising: an antigen binding domain; and a constant domain, wherein the constant domain comprises an IgA2 heavy chain constant region comprising an IgA2 CH1 region, an IgA2 CH2 region, and an IgA2 CH3 region, and wherein the IgA2 heavy chain constant region comprises, relative to a WT IgA2 heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1 : an N45.2G amino acid substitution, an N135Q amino acid substitution, a deletion of C147, and a deletion of Y148, numbered according to the IMGT scheme.

[0060] Provided herein is an antibody or functional fragment thereof, comprising: an antigen binding domain; and a constant domain, wherein the constant domain comprises an IgA2 heavy chain constant region comprising an IgA2 CH1 region, an IgA2 CH2 region, and an IgA2 CH3 region, and wherein the IgA2 heavy chain constant region comprises, relative to a WT IgA2 heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1 : an N45.2G amino acid substitution, an N114T amino acid substitution, an I115L amino acid substitution, a T116S amino acid substitution, an amino acid substitution selected from the group consisting of N15.2G, N15.2Q, and N15.2T, and a deletion of C-terminal amino acids P131-Y148, numbered according to the IMGT scheme.

[0061] In some embodiments, the antibody or functional fragment thereof of the above aspects further comprises, relative to a WT IgA2 heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 1 : a C86S amino acid substitution, a P124R amino acid substitution, a deletion of C147, a deletion of Y148, a L15.3I amino acid substitution, a T16S amino acid substitution, or a combination thereof, numbered according to the IMGT scheme.

[0062] In some embodiments, the IgA2 heavy chain constant region comprises an amino acid sequence that is at least 95% identical to a sequence selected from any one of SEQ ID NOs: 18-21. In some embodiments, the antibody or functional fragment thereof is non-glycosylated.

[0063] In some embodiments, the antibody or functional fragment thereof has an increased circulating half-life compared to a corresponding IgA comprising one or more of wild-type amino acid residues N45.2, N114, I115, T116, N15.2, or C-terminal amino acid residues P131-Y148, numbered according to the IMGT scheme.

[0064] In some embodiments, the antibody or functional fragment thereof induces increased antibody-dependent cell-mediated cytotoxicity (ADCC) compared to a corresponding antibody comprising an IgG heavy chain constant domain. In some embodiments, the antibody or functional fragment thereof exhibits increased thermal stability compared to a corresponding IgA comprising one or more of wild-type amino acid residues N45.2, N114, 1115, T116, N15.2, or C-terminal amino acid residues P131-Y148, numbered according to the IMGT scheme. In some embodiments, the antibody or functional fragment thereof exhibits decreased glycosylation compared to a corresponding IgA comprising one or more of wild-type amino acid residues N45.2, N114, 1115, T116, N15.2, or C-terminal amino acid residues P131-Y148, numbered according to the IMGT scheme.

[0065] incorporated by reference

[0066] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. BRIEF DESCRIPTION OF DRAWINGS

[0068] The features of the present disclosure are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present disclosure will be obtained by reference to the following detailed description and drawings, which sets forth illustrative embodiments in which the principles of the present disclosure are utilized, and in which:

[0069] Figure 1 is a diagram showing the amino acid sequence of an IgA2 heavy chain (UniProt Reference No: A0A0G2JMB2) (SEQ ID NO: 1). Highlighted amino acids depict amino acids that undergo substitution in some embodiments described herein. Underlined sequences indicate a tailpiece, all or part of which can be deleted in some embodiments described herein.

[0070] Figure 2 is a diagram showing the amino acid sequence of an IgA2 heavy chain (UniProt Reference No: P01877) (SEQ ID NO: 2). Highlighted amino acids depict amino acids that undergo substitution in some embodiments described herein. Underlined sequences indicate a tailpiece, all or part of which can be deleted in some embodiments described herein.

[0071] Figure 3is a graphic showing the amino acid sequence of a representative IgA2 heavy chain (UniProt Reference Number: A0A286YEY5) (SEQ ID NO: 3). The highlighted amino acids depict amino acids that undergo substitution or deletion in some embodiments described herein. In some additional embodiments, the corresponding amino acids can be deleted in comparable IgA antibodies or comparable chimeric antibodies having an IgA2 constant region.

[0072] Figures 4A-4D shows a schematic representation of engineered IgA variants relative to wild-type IgA (IgA2(m1)). Figure 4A shows a representation of wild-type (WT) IgA; IgA2m1 antibody. Wild-type (WT) IgA (IgA2m1) comprises three N-glycosylation sites in its CH domain and 1 glycosylation site in its tailpiece.

[0073] Figure 4B shows a representation of engineered IgA3.0+ (plus) variant. The engineered IgA3.0+ variant is generated by engineering the IgA2m1 antibody to comprise a heavy and light chain linkage stabilized via a CH1-P124R mutation, removal of two free cysteines, where 1 is mutated to a serine (CH2-C86S) and the second (CH3-CHS-C147del) is removed by deletion of the two final amino acids of the tailpiece. In addition, three N-linked glycosylation sites are removed by substitution of key amino acids in three N-glycosylation motifs. Mutations in these three N-glycosylation motifs include CH1-N45.2G; CH2-N114T-I115L-T116S; CH3-CHS-N135Q.

[0074] Figure 4C shows a representation of engineered IgA3.0- or IgA3.0min variant comprising deletion of the entire tailpiece (CH3-CHS-P131-Y148del). The IgA3.0min variant comprises a stabilized heavy and light chain linkage (CH1-P124R mutation), deletion of the entire tailpiece (CH3-CHS-P131-Y148del), lack of two free cysteines, where 1 is mutated to a serine (CH2-C86S) and the second (CH3-CHS-C147del) is the tailpiece deletion. In addition, three N-linked glycosylation sites are removed by substitution of key amino acids in 2 N-glycosylation motifs, CH1-N45.2G and CH2-N114T-I115L-T116S, and CH3-CHS-N135Qdel is deleted by tailpiece deletion.

[0075] Figure 4DRepresentations of engineered IgA4.0 variants are shown, which comprise all the features of IgA3.0min and further comprise mutations in the final N-linked glycosylation motif CH2-N15.2. Thus, the IgA4.0 variants comprise a stabilized heavy and light chain junction (CH1-P124R mutation), deletion of the entire tailpiece (CH3-CHS-P131-Y148del), lack of two free cysteines, with 1 mutated to serine (CH2-C86S) and the second (CH3-CHS-C147del) is a tailpiece deletion. In addition, four N-linked glycosylation sites are removed by substitution of key amino acids in four N-glycosylation motifs (CH1-N45.2G; CH2-N114T-I115L-T116S; CH3-CHS-N135Q; and one of CH2-N15.2G, CH2-N15.2Q, CH2-N15.2T, or CH2-N15.2T-L15.3I-T16S). The IgA4.0 variants are aglycosylated IgAs.

[0076] Figure 5A and Figure 5B Yields of IgA3.0min antibody variants are shown.

[0077] Figure 5A Concentrations of anti-Her2 IgA antibodies (i.e., IgA2-Her2) determined by ELISA on supernatants of HEK293F cells transfected with different heavy chain (HC):light chain (LC):pAdvantage ratios are shown.

[0078] Figure 5B Concentrations of anti-CD47 IgA3.0min antibodies (i.e., IgA3.0min antibodies comprising anti-CD47 variable domains (IgA3.0min-C47A8-CQ)) determined by ELISA on supernatants of HEK293F cells transfected with different heavy chain (HC):light chain (LC):pAdvantage ratios are shown. Variable domains were obtained from C47A8-CQ antibodies.

[0079] Figures 6A-6C Comparison of antibody yields of IgA3.0min antibody variants in HEK293F cells and ExpiCHO-S cells determined by ELISA is shown.

[0080] Figure 6A Comparison of yields of anti-CD20 IgA3.0min-Obi antibodies in HEK293F cells and ExpiCHO cells is shown. IgA3.0min-Obi antibodies comprise IgA3.0min and Obinutuzumab (Obi) variable domains.

[0081] Figure 6B A comparison of the yield of anti-Her2 IgA3.0min-Her2 antibody in HEK293F cells and ExpiCHO cells is shown. The IgA3.0min-Her2 antibody comprises IgA3.0min with an anti-Her2 variable domain.

[0082] Figure 6C A comparison of the yield of anti-mCTLA4 IgA3.0min-mCTLA4 antibody in HEK293F cells and ExpiCHO cells is shown. The IgA3.0min-mCTLA4 comprises IgA3.0min with an anti-mCTLA4 variable domain.

[0083] Figures 7A-7D Concentrations of IgA3.0min antibody variants in ExpiCHO-S cells transfected with different heavy chain (HC):light chain (LC):pAdvantage ratios are shown.

[0084] Figure 7A Concentrations of anti-GD2 IgA3.0min-ch14.18 antibody are shown. The IgA3.0min-ch14.18 antibody comprises IgA3.0min with a ch14.18 variable domain.

[0085] Figure 7B Concentrations of anti-gp75 IgA3.0min-TA99 antibody are shown. The IgA3.0min-TA99 antibody comprises IgA3.0min with a TA99 variable domain.

[0086] Figure 7C Concentrations of anti-Her2 IgA3.0min-Her2 antibody are shown. The IgA3.0min-Her2 antibody comprises IgA3.0min with an anti-Her2 variable domain (the anti-Her2 variable domain is derived from the anti-Her2 antibody trastuzumab).

[0087] Figure 7D Concentrations of anti-CD20 IgA3.0min-Obi antibody are shown. The IgA3.0min-Obi antibody comprises IgA3.0min with an obinutuzumab (Obi) variable domain.

[0088] Figures 8A-8D Yields of IgA4.0 antibody variants in ExpiCHO-S cells transfected with different heavy chain (HC):light chain (LC):pAdvantage ratios are shown.

[0089] Figure 8AThe generation of the anti-CD20 IgA4.0_NG-Obi variant is illustrated. The IgA4.0_NG-Obi variant comprises IgA4.0 with a CH2-N15.2G mutation at the glycosylation site and a variable domain from Obi.

[0090] Figure 8B The generation of the anti-CD20 IgA4.0_NT-Obi variant is shown. The IgA4.0_NT-Obi variant contains IgA4.0 with a CH2-N15.2T mutation at the glycosylation site and a variable domain from Obi.

[0091] Figure 8C The generation of the anti-CD20 IgA4.0_NQ-Obi variant is illustrated. The IgA4.0_NQ-Obi variant comprises IgA4.0 with a CH2-N15.2Q mutation at the glycosylation site and a variable domain from Obi.

[0092] Figure 8D The generation of the anti-CD20 IgA4.0_NLT-TIS-Obi variant is illustrated. The IgA4.0_NLT-TIS-Obi variant comprises IgA4.0 with an N15.2T-L15.3I-T16S mutation at the glycosylation site and a variable domain from Obi.

[0093] Figures 9A-9B This demonstrates the use of KappaSelect columns (GE Healthcare) to extract cells from the production cell line ExpiCHO-S (… Figure 9A ) and HEK293F ( Figure 9B Elution profile of IgA 3.0 min-Obi in the supernatant of )

[0094] Figures 9C-9D The image shows cells from the production cell line ExpiCHO-S ( Figure 9C ) and HEK293F ( Figure 9D The SEC separation spectrum of IgA 3.0 min-Obi showed that no aggregates were observed during SEC separation.

[0095] Figures 10A-10B This demonstrates the use of KappaSelect columns (GE Healthcare) to extract cells from the production cell line ExpiCHO-S (… Figure 10A ) and HEK293F ( Figure 10B Elution profile of IgA 3.0 min-Her2 in the supernatant of )

[0096] Figures 10C-10D The image shows cells from the production cell line ExpiCHO-S ( Figure 10C ) and HEK293F (Figure 10D ) IgA3.0min-Her2 SEC elution profile, no aggregates observed at SEC separation.

[0097] Figure 11A A typical elution profile of IgA4.0-Obi from supernatant from production cell line ExpiCHO-S using KappaSelect column (GE Healthcare) is shown.

[0098] Figure 11B SEC elution profile of IgA4.0-Obi from production cell line ExpiCHO-S, no aggregates observed at SEC separation is shown.

[0099] Figures 12A-12E Binding of IgA3.0+-Obi and IgA3.0min-Obi to CD20 positive Daudi cells analyzed by flow cytometry is shown.

[0100] Figure 12A Unstained CD20+ Daudi cell control is shown.

[0101] Figure 12B Daudi cell negative control stained with secondary antibody only is shown.

[0102] Figure 12C Positive control stained with anti-CD20 IgA Obi (5ug / mL) is shown.

[0103] Figure 12D Daudi cells stained with IgA3.0+-Obi (supernatant) is shown. Figure 12E Daudi cells stained with IgA3.0min-Obi (supernatant) is shown. Figures 12D-12E Daudi cells stained with supernatant from HEK293F cells transfected with IgA3.0min-Obi or IgA3.0+-Obi are shown. Both variant IgA3.0+-Obi ( Figure 12D ) and IgA3.0min-Obi ( Figure 12E ) bind CD20 positive Daudi to the same extent as IgA Obi ( Figure 12C ).

[0104] Figure 13Binding of the Fc portion of IgA3.0min-Obi to PMNs as evaluated by a PMN binding assay is shown. PMNs were added to ELISA plate wells coated with different concentrations of antibody. A series of washes determined the strength of binding of the Fc portion of IgA3.0min-Obi and IgA2 to PMNs. After the 6th wash, a binding plot was generated. IgA3.0min-Obi showed equivalent to better binding to PMNs compared to wild-type IgA2.

[0105] Figure 14 Equivalent coating concentrations of IgA3.0min compared to wild-type IgA2 are shown.

[0106] Figure 15 Binding analysis of IgA4.0 variants is shown. Supematants from ExpiCHO-S cells transfected with IgA4.0 variants (IgA4.0_NT-Obi, IgA4.0_NQ-Obi, IgA4.0_NG-Obi, and IgA4.0_NLT-TIS-Obi) were evaluated for binding to SKBR3 cells expressing CD20. All IgA4.0-Obi variants bound to SKBR3-CD20 to the same extent as supematants from ExpiCHO-S cells transfected with IgA3.0min-Obi or purified IgA3.0min-Obi.

[0107] Figures 16A-16D IgA variant-induced PMN-mediated ADCC against target cells is shown.

[0108] Figure 16A IgA3.0min-Her2 antibodies induced ADCC against SKBR3 cells to a similar or better extent than IgA2-Her2 as determined by chromium release assay is shown.

[0109] Figures 16B-16C IgA3.0min-Obi antibodies produced by HEK293F cells or ExpiCHO-S cells induced similar levels of ADCC against Ramos cells ( Figure 16B ) and Daudi cells ( Figure 16C ) as evaluated by chromium release assay.

[0110] Figure 16DIgA variants induced ADCC against Daudi cells. Purified IgA3.0min-Obi, supernatant from cells transfected with IgA3.0min-Obi, supernatant from cells transfected with IgA4.0_NG-Obi, supernatant from cells transfected with IgA4.0_NQ-Obi, supernatant from cells transfected with IgA4.0_NT-Obi, and supernatant from cells transfected with IgA4.0_NLT-TIS-Obi showed increased ADCC compared to purified IgG1-Obi. IgA4.0-Obi variants (IgA4.0_NG-Obi, IgA4.0_NQ-Obi, IgA4.0_NT-Obi, and IgA4.0_NLT-TIS-Obi) showed similar levels of ADCC induction compared to purified IgA3.0min-Obi, supernatant from cells transfected with IgA-3.0min-Obi.

[0111] Figures 17A-17C Thermal stability of IgA variants is shown. Thermal stability of IgA3.0min and IgA4.0 was determined using SYPRO Orange thermal shift assay. Figure 17A It is shown that engineered IgA3.0min variants (IgA3.0min with Obi variable domain and IgA3.0min with 2.3D11 variable domain) show increased thermal stability compared to wild type IgA2(m1) (i.e., IgA2 with ch14.18 variable domain and IgA2 with Her2 variable domain).

[0112] Figure 17A It is also shown that engineered IgA4.0min variants (IgA4.0NQ, IgA4.0 NT, IgA4.0 NLT-TIS, and IgA4.0NG all with Obi variable domain) show increased thermal stability compared to wild type IgA2(m1) (i.e., IgA2 with ch14.18 variable domain and IgA2 with Her2 variable domain). Increased thermal stability of engineered IgA3.0min variants and engineered IgA4.0 variants relative to wild type IgA2(m1) is indicated by a shift to higher temperatures.

[0113] Figure 17B A graph showing the average Tm values of engineered IgA3.0min variants and engineered IgA4.0 variants analyzed relative to wild type IgA2(m1) is shown. The graph shows that engineered IgA3.0min variants and engineered IgA4.0 variants are more heat resistant compared to wild type IgA2.

[0114] Figure 17C The functionality of antibodies exposed to increasing temperatures in PMN-ADCC against Raji cells expressing CD20 is shown. Wild-type IgA2(m1) showed decreasing efficacy starting at 47°C, while both IgA3.0min-Obi and IgA4.0_NT-Obi were still effective. At 71°C, both IgA3.0min-Obi and IgA4.0_NT-Obi provided more than 50% killing efficacy, while IgA2(m1) was non-functional at this temperature.

[0115] Figure 18 The effect of PNGase F treatment on deglycosylation of engineered IgA3.0min variants and engineered IgA4.0 variants compared to wild-type IgA2 is shown. Wild-type IgA2 (IgA2(m1)-UMAB10) shows the greatest migration, while the engineered IgA3.0min variant (IgA3.0min-Obi) shows a slight migration compared to wild-type IgA2, indicating reduced glycosylation. The engineered IgA4.0 variant (IgA4.0_NG-Obi) does not show migration compared to the engineered IgA3.0min variant and wild-type IgA2, indicating reduced glycosylation.

[0116] Figures 19A-19G The overall glycosylation profile of wild-type IgA2 and engineered IgA variants determined with MALDI-TOF-MS is shown

[0117] Figure 19A The overall glycosylation profile of wild-type IgA2 (IgA2-Her2) produced in HEK293 cells is shown.

[0118] Figure 19B The overall glycosylation profile of the engineered IgA3.0min variant (IgA3.0min-Her2) produced in HEK293 cells is shown. The profile shows all signals from the single glycosylation sites present in the engineered IgA3.0min variant.

[0119] Figure 19C Glycosylation site-specific analysis of the engineered IgA3.0min variant (IgA3.0min-Obi) produced in HEK293F and ExpiCHO-S is shown. IgA3.0min-Obi produced in ExpiCHO-S shows less free galactose, which means less sensitivity to ASGPR-dependent clearance in the liver.

[0120] Figures 19D-19GNon-denaturing MS analysis is shown for the following four IgA4.0 variants: IgA4.0_NG-Obi( Figure 19D ), IgA4.0_NQ-Obi( Figure 19E ), IgA4.0_NT-Obi( Figure 19F ), and IgA4.0_NLT-TIS-Obi( Figure 19G ). The large plot shows the broad mass range of the antibodies, and the inset zooms in on the highest peaks. The observed masses are practically equal to the theoretical masses, ruling out the presence of bulky N-glycans, indicating the absence of glycosylation in the IgA4.0 variants.

[0121] Figures 20A-20B Pharmacokinetic and drug distribution analysis of engineered IgA variants is shown. Wild-type-IgG1-dinutuximab, wild-type-IgA2-dinutuximab, and IgA3.0min-dinutuximab, IgA3.0min- obinutuzumab, IgA4.0- obinutuzumab were injected into BALB / c mice in an amount of 100 pg, and blood was analyzed by ELISA at the indicated time points.

[0122] Figure 20A IgA3.0min variants (IgA3.0min-dinutuximab) are shown to display an extended half-life compared to their wild-type IgA2 counterparts.

[0123] Figure 20B Comparison between IgA3.0min and IgA4.0 in the form of obinutuzumab is shown. The engineered IgA4.0 variant (IgA4.0- obinutuzumab) displays a superior half-life profile compared to the engineered IgA3.0min variant (IgA3.0min- obinutuzumab). Obinutuzumab IgA4.0 is still detectable after 120 hours.

[0124] Figures 21A-21B Biodistribution of IgG1 dinutuximab and engineered IgA3.0min variant containing variable domains from dinutuximab (IgA3.0min dinutuximab) is shown. Indium-111 radiolabeled IgG1 dinutuximab and engineered IgA3.0min variant (IgA3.0min dinutuximab) were injected intravenously (i.v.) into mice for biodistribution analysis. Mice were monitored to track the distribution of the antibodies after 24 hours Figure 21A ) and after 48 hours Figure 21B ). Significant infiltration of the tumors was observed for both IgG1 and engineered IgA3.0min variant.

[0125] Figure 22 Quantification of the distribution of radiolabeled IgGl dinutuximab and engineered IgA3.0min variant (IgA3.0min dinutuximab) in mice from Figures 21A-21B The ratio of tumor signal to liver signal was determined to adjust for background signal. This graph shows that the engineered IgA3.0min variant (IgA3.0min dinutuximab) shows an increased tumor / liver ratio compared to IgGl dinutuximab.

[0126] Figure 23 Inhibition of tumor growth after administration of engineered IgA3.0min variant (IgA3.0min-Her2) in an established tumor model is shown. A431-Luc2-Her2 cells were intraperitoneally injected into hCD89 transgenic or non-transgenic SCID mice on day 0, followed by a subcutaneous injection of pegG-CSF on day 6. Bioluminescence signal was measured starting on day 6 and on this day mice were randomized into different treatment groups and a significant signal was measured. Treatment started on day 7 with an intraperitoneal injection of 10 ug IgA3.0min-Her2 daily for 10 days. Bioluminescence signal was measured at the indicated time points.

[0127] The present disclosure details

[0128] The following description and examples detail embodiments of the present disclosure. It is to be understood that the present disclosure is not limited to the specific embodiments described herein, and as such can vary. One skilled in the art will recognize many variations and modifications of this disclosure from the description and examples below.

[0129] All terms are intended to be interpreted broadly. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0130] The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0131] Although various features of the present disclosure can be described in the context of individual embodiments, the features can also be provided alone or in any suitable combination. Conversely, although the present disclosure can be described in the context of individual embodiments for clarity, the present disclosure can also be implemented in a single embodiment.

[0132] Definitions

[0133] The following definitions supplement those in the art and are directed to the present application, and are not to be attributed to any related or unrelated case, such as any commonly owned patent or application. Although any methods and materials similar or equivalent to those described herein can be used in the practice of the present disclosure, the preferred materials and methods are described herein. Accordingly, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0134] In this application, the use of the singular includes the plural, unless specifically stated otherwise. It must be noted that as used herein the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. In this application, the use of "or" means "and / or" unless stated otherwise. Furthermore, the use of the term "including" as well as other forms such as "include", "includes" and "included" is not limiting.

[0135] References in the specification to "some embodiments", "an embodiment”, "one embodiment” or "other embodiments” indicate that the particular feature, structure, or characteristic being described is included in at least some embodiments, but not necessarily all embodiments, of the disclosure.

[0136] As used in the specification and in one or more claims (s), the words "comprising" (and any form of comprising, such as "comprise" and "comprises"), "having" (and any form of having, such as "have" and "has"), "including" (and any form of including, such as "includes" and "include") or "containing" (and any form of containing, such as "contains" and "contain") are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. It is contemplated that any embodiment discussed in the specification can be implemented with respect to any method or composition of the present disclosure, and vice versa. Furthermore, combinations of compositions of the present disclosure can be used to implement methods of the present disclosure.

[0137] The term“about” or“approximately” means within an acceptable error range for the particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined, i.e., the limitations of the measurement system. For example,“about” can mean within 1 or more than 1 standard deviation, per the practice in the art. Alternatively,“about” can mean ranges approximately 20%, approximately 10%, approximately 5%, or approximately 1% of a particular value. In other instances,“about 10” can include 10 and any amount from 9 to 11.

[0138] In yet other instances, the term“about” in reference to a numerical value can also include a range of values plus or minus 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1% of that value. Alternatively, particularly in reference to biological systems or processes, the term“about” can mean within an order of magnitude, preferably within 5-fold and more preferably within 2-fold of a value. When a particular value is described in the application and claims, unless otherwise stated the term“about” shall be assumed to mean within an acceptable error range for the particular value.

[0139] As used herein, the term“antibody” refers to an immunoglobulin (Ig), whether natural or partially or wholly synthetically produced. The term also encompasses any polypeptide or protein having a binding domain that is or is homologous to an antigen binding domain. The term also includes“antigen binding fragments” or“functional fragments thereof,” or“fragments of an antibody,”“antibody fragments,”“functional fragments of an antibody,” and other interchangeable terms for similar binding fragments as described below.

[0140] Antibodies include, for example, monoclonal antibodies, chimeric antibodies, humanized antibodies, human antibodies, recombinant antibodies, chemically engineered antibodies, deimmunized antibodies, affinity matured antibodies, multispecific antibodies (e.g., bispecific antibodies and polyreactive antibodies), heteroconjugated antibodies, antibody fragments, and combinations thereof (e.g., monoclonal antibodies that are also deimmunized, humanized antibodies that are also deimmunized, etc.).

[0141] Antibodies can be, for example, murine antibodies, chimeric antibodies, humanized antibodies, heteroconjugated antibodies, bispecific antibodies, diabodies, triabodies, or tetrabodies. Antigen binding fragments can include, for example, Fab’, F(ab’)2, Fab, Fv, rIgG, scFv, hcAb (heavy chain antibody), single domain antibody, VHH, VNAR, sdAb, or nanobody.

[0142] The term "monoclonal antibody" as used herein refers to antibodies produced by a single clone of B cells and bind to the same epitope. In contrast, "polyclonal antibodies" refers to a population of antibodies produced by different B cells and bind to different epitopes of the same antigen. A complete antibody is typically composed of four polypeptides: two identical copies of a heavy (H) chain polypeptide and two identical copies of a light (L) chain polypeptide. Each heavy chain comprises one N-terminal variable (VH) region and three C-terminal constant (CH1, CH2, and CH3) regions, and each light chain comprises one N-terminal variable (VL) region and one C-terminal constant (CL) region. The variable regions of each pair of light and heavy chains form the antigen binding site of the antibody. The VH and VL regions have similar general structures, with each region comprising four framework regions, the sequences of which are relatively conserved. The framework regions are connected by three complementarity determining regions (CDRs). The three CDRs, referred to as CDR1, CDR2, and CDR3, form the "hypervariable region" of the antibody responsible for antigen binding.

[0143] As used herein, a "chimeric antibody" is an antibody that comprises amino acid sequences derived from two different species or two different sources and includes synthetic molecules. By way of non-limiting example, an antibody comprises non-human CDRs and human variable region framework or constant regions or Fc regions, an antibody has binding domains from two different monoclonal antibodies, or an antibody comprises one or more amino acid residue mutations to increase or decrease the biological activity or binding of a portion of the antibody. In certain embodiments, a recombinant antibody is produced from a recombinant DNA molecule or is synthesized. In certain embodiments, the antibodies described herein are one or more polypeptides encoded by one or more polynucleotides.

[0144] As used herein, "recognize" refers to the association or binding between an antigen binding domain and an antigen. As used herein, "antigen" refers to an antigenic substance capable of triggering an immune response in a host. An antigenic substance can be a molecule, such as a costimulatory molecule capable of triggering an immune response in a host.

[0145] As used herein, "antibody construct" refers to a construct comprising an antigen binding domain and an Fc domain.

[0146] As used herein, "binding domain" refers to an antibody or non-antibody domain.

[0147] As used herein, an“antigen binding domain” refers to a binding domain from an antibody or from a non-antibody that is capable of binding to an antigen. The antigen binding domain can be a tumor antigen binding domain or a domain capable of binding to an antigen on an antigen presenting cell, such as a molecule. When there is more than one antigen binding domain present in a particular conjugate or antibody construct, the antigen binding domains can be numbered (e.g., first antigen binding domain, second antigen binding domain, third antigen binding domain, etc.). Different antigen binding domains in the same conjugate or construct can target the same antigen or different antigens (e.g., a first antigen binding domain is capable of binding to a tumor antigen, a second antigen binding domain is capable of binding to a molecule on an antigen presenting cell (APC antigen), and a third antigen binding domain is capable of binding to an APC antigen). The term“antigen binding domain” refers to a fragment of an antibody comprising a region that binds specifically to an epitope and is complementary to a portion or all of an antigen. An antigen binding domain can be provided by, for example, one or more antibody variable domains (also referred to as antibody variable regions). In particular, an antigen binding domain comprises an antibody light chain variable region (VL) and an antibody heavy chain variable region (VH).

[0148] As used herein, the term“antigen” means a molecule or a portion of a molecule capable of reacting with the recognition site of an antibody. The term“antigen” also includes a molecule or a portion of a molecule that is capable of eliciting an immune response by itself or together with an adjuvant or carrier (also referred to as an“immunogen”). The term“antigen” as used herein includes a molecule or a portion of a molecule (epitope) that is capable of eliciting antibody production or capable of binding to an antibody. The term includes substances that react with antibodies strongly and with high specificity, and also includes substances that react with antibodies weakly and / or with low affinity.

[0149] The term "epitope" as used herein refers to a determinant that interacts with a particular antigenic binding site (becomes a paratope) in the variable region of an antibody molecule. A single antigen can have more than one epitope. Thus, different antibodies can bind to different regions of an antigen and can have different biological effects. Epitopes can be conformational or linear. Conformational epitopes result from spatial juxtaposition of amino acids from different segments of a linear polypeptide chain. Linear epitopes are formed by contiguous amino acid residues in the polypeptide chain. In certain instances, an epitope can include portions of carbohydrates, phosphoryl groups, or sulfonyl groups on the antigen. Various techniques known to those of ordinary skill in the art can be used to determine whether an antigen binding domain of an antibody interacts with "one or more amino acids" in a polypeptide or protein. Exemplary techniques include, e.g., routine cross-blocking assays such as those described in Antibodies, Harlow and Lane (Cold Spring Harbor Press, Cold Spring Harb., NY), alanine scanning mutational analysis, peptide mapping analysis (Reineke, 2004, Methods Mol Biol 248:443-463), and peptide cleavage analysis. In addition, methods such as epitope excision, epitope extraction, and chemical modification of antigens can be employed (Tomer, 2000, Protein Science 9:487-496). Another method that can be used to identify amino acids within a polypeptide that interact with an antigen binding domain of an antibody is hydrogen / deuterium exchange detected by mass spectrometry. Generally, the hydrogen / deuterium exchange method involves deuterium labeling of a protein of interest, followed by binding of the antibody to the deuterium-labeled protein. Next, the protein / antibody complex is transferred to water to allow hydrogen-deuterium exchange to occur at all residues except those protected by the antibody, which remain deuterium-labeled. After the antibody dissociates, the target protein is subjected to protease cleavage and mass spectrometry analysis, revealing the deuterium-labeled residues that correspond to the specific amino acids that interact with the antibody. See, e.g., Ehring (1999) Analytical Biochemistry 267(2):252-259; Engen and Smith (2001) Anal. Chem. 73:256A-265A. X-ray crystallography of antigen / antibody complexes can also be used for epitope mapping purposes.

[0150] As used herein, "antibody antigen binding domain" refers to a binding domain from an antibody that is capable of binding to an antigen.

[0151] As used herein, "Fc domain" refers to an Fc domain from an antibody or from a non-antibody that is capable of binding to an Fc receptor. As used herein, "Fc domain" and "Fc-containing domain" are used interchangeably.

[0152] As used herein, "target binding domain" refers to a construct comprising an antigen binding domain from an antibody or from a non-antibody that is capable of binding to an antigen.

[0153] As used herein, the abbreviations for the natural 1 -enantiomeric amino acids are conventional and can be as follows: alanine (A, Ala); arginine (R, Arg); asparagine (N, Asn); aspartic acid (D, Asp); cysteine (C, Cys); glutamic acid (E, Glu); glutamine (Q, Gin); glycine (G, Gly); histidine (H, His); isoleucine (I, He); leucine (L, Leu); lysine (K, Lys); methionine (M, Met); phenylalanine (F, Phe); proline (P, Pro); serine (S, Ser); threonine (T, Thr); tryptophan (W, Trp); tyrosine (Y, Tyr); valine (V, Val). Unless otherwise specified, X can indicate any amino acid. In some aspects, X can be asparagine (N), glutamine (Q), histidine (H), lysine (K), or arginine (R).

[0154] The expression "pharmaceutically acceptable" is employed herein to refer to those compounds, materials, compositions, and / or dosage forms that are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit / risk ratio.

[0155] The phrase "pharmaceutically acceptable excipient" or "pharmaceutically acceptable carrier" as used herein means a pharmaceutically-acceptable substance, composition or vehicle, such as a liquid or solid filler, diluent, excipient, solvent or encapsulating material. Each carrier must be "acceptable" in the sense of being compatible with the other ingredients of the formulation and not injurious to the patient. Some examples of materials which can serve as pharmaceutically acceptable carriers include: (1) sugars, such as lactose, glucose and sucrose; (2) starches, such as corn starch and potato starch; (3) cellulose, and its derivatives, such as sodium carboxymethyl cellulose, ethyl cellulose and cellulose acetate; (4) powdered tragacanth; (5) malt; (6) gelatin; (7) talc; (8) excipients, such as cocoa butter and suppository waxes; (9) oils, such as peanut oil, cottonseed oil, safflower oil, sesame oil, olive oil, corn oil and soybean oil; (10) glycols, such as propylene glycol; (11) polyols, such as glycerin, sorbitol, mannitol and polyethylene glycol; (12) esters, such as ethyl oleate and ethyl laureate; (13) agar; (14) buffering agents, such as magnesium hydroxide and aluminum hydroxide; (15) alginic acid; (16) pyrogen-free water; (17) isotonic saline; (18) Ringer's solution; (19) ethyl alcohol; (20) phosphate buffer solutions; and (21) other non-toxic compatible substances employed in pharmaceutical formulations.

[0156] The terms "cancer," "tumor," "proliferative disorder," "malignant tumor," or "malignancy" relate to a physiological condition in a mammal characterized by unregulated or unwanted cell growth. Cancer is a class of diseases in which a group of cells display uncontrolled growth or unwanted growth. Cancer cells can also spread to other locations, which can lead to the formation of metastases. For example, the spread of cancer cells within the body can occur via the lymph or blood. Unregulated growth, invasion, and metastasis formation are also known as malignant properties of cancer. These malignant properties distinguish cancer from benign tumors, which typically do not invade or metastasize.

[0157] "Antigen recognition moiety" or "antibody recognition domain" refers to a molecule or a portion of a molecule that specifically binds to an antigen. In one embodiment, the antigen recognition moiety is an antibody, an antibody-like molecule, or a fragment thereof, and the antigen is a tumor antigen or an infectious disease antigen.

[0158] The terms“fragment of an antibody,”“antibody fragment,”“functional fragment of an antibody,”“antigen binding portion,” or their grammatical equivalents are used interchangeably herein and mean one or more fragments or portions of an antibody that retain the ability to bind specifically to an antigen (see generally, Holliger et al., Nat. Biotech., 23(9): 1126-1129 (2005)). An antibody fragment desirably comprises, for example, one or more CDRs, a variable region (or portion thereof), a constant region (or portion thereof), or combinations thereof. Examples of antibody fragments include, but are not limited to, (i) a Fab fragment, which is a monovalent fragment consisting of the VL, VH, CL, and CHI domains; (ii) a F(ab’)2 fragment, which is a bivalent fragment comprising two Fab fragments connected by a disulfide bridge at the stalk region; (iii) a Fv fragment, which consists of the VL and VH domains of a single arm of an antibody; (iv) a single chain Fv (scFv), which is a monovalent molecule consisting of the two domains of a Fv fragment (i.e., VL and VH) connected by a synthetic linker that enables the two domains to associate to form a single polypeptide chain (see, e.g., Bird et al., Science, 242: 423-426 (1988); Huston et al., Proc. Natl. Acad. Sci. USA, 85: 5879-5883 (1988); and Osbourn et al., Nat. Biotechnol., 16: 778 (1998)), and (v) a diabody, which is a dimer of polypeptide chains, wherein each polypeptide chain comprises a VH connected to a VL by a peptide linker that is too short to allow pairing between the VHand VL on the same polypeptide chain, thereby driving pairing between complementary domains on different VH-VL polypeptide chains to produce a dimeric molecule with two functional antigen binding sites. Antibody fragments are known in the art and are described in greater detail in, e.g., U.S. Patent No. 8,603,950. Other antibody fragments can include variable fragments of heavy chain antibodies (VHHs).

[0159] The term "conservative amino acid substitution" or "conservative mutation" refers to the replacement of one amino acid by another amino acid of common property. One functional way of defining common properties among individual amino acids is by analyzing the normalized frequency of amino acid changes between corresponding proteins of homologous organisms (Schulz, G. E. and Schirmer, R. H., Principles of Protein Structure, Springer-Verlag, New York (1979)). According to such an analysis, groups of amino acids can be defined, wherein amino acids within a group prefer to exchange with each other and are thus most similar to each other in their impact on the overall protein structure (Schulz, G. E. and Schirmer, R. H., supra). Examples of conservative mutations include amino acid substitutions of amino acids within the above groups, e.g., lysine for arginine and vice versa, such that a positive charge can be maintained; glutamic acid for aspartic acid and vice versa, such that a negative charge can be maintained; serine for threonine, such that a free -OH can be maintained; and glutamine for asparagine, such that a free -NH2can be maintained. Alternatively or additionally, the therapeutic IgA antibody can comprise an amino acid sequence of the reference protein with at least one non-conservative amino acid substitution.

[0160] The term "non-conservative mutation" or "non-conservative amino acid substitution" relates to amino acid substitutions between different groups, e.g., lysine for tryptophan or phenylalanine for serine, etc. In this case, it is preferred that the non-conservative amino acid substitution does not interfere with or inhibit the biological activity of the therapeutic IgA antibody. The non-conservative amino acid substitution can enhance the biological activity of the therapeutic IgA antibody, such that the biological activity of the therapeutic IgA antibody is increased compared to the wild-type therapeutic IgA antibody.

[0161] As used herein, "humanized" antibody refers to a form of a particular chimeric immunoglobulin, immunoglobulin chain or fragment thereof (such as Fv, Fab, Fab', F(ab')2 or other antigen- binding subsequence of an antibody) that contains minimal sequence derived from non-human immunoglobulin. For the most part, humanized antibodies are human immunoglobulins (recipient antibody) in which residues from a CDR of the recipient are replaced by residues from a CDR of a non-human species (donor antibody) such as mouse, rat, or rabbit having the desired specificity, affinity, and capacity. In some instances, Fv framework region (FR) residues of the human immunoglobulin are replaced by corresponding non-human residues. Furthermore, humanized antibodies can comprise residues that are found neither in the recipient antibody nor in the imported CDR or framework sequences, but are included to further improve and optimize antibody performance. Generally, the humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the CDR regions correspond to those of a non-human immunoglobulin and all or substantially all of the FR regions are those of a human immunoglobulin consensus sequence. The humanized antibody optimally also will include at least a portion of an immunoglobulin constant region or domain (Fc). Other forms of humanized antibodies have one or more CDRs (one, two, three, four, five, six) that are altered with respect to the original antibody, which are also referred to as "derived from" one or more CDRs from the original antibody.

[0162] As used herein, "isolated antibody" is one which has been separated from a component of its natural environment and / or recovered from a component of its natural environment. Contaminant components of its natural environment are materials that would interfere with diagnostic or therapeutic uses of the antibody, and can include enzymes, hormones, and other proteinaceous or nonproteinaceous components. In preferred embodiments, the antibody is purified (1) to greater than 95% by weight, and most preferably more than 99% by weight, as determined by the Lowry method, (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 reducing or nonreducing conditions, using Coomassie blue or, preferably, silver stain. Isolated antibody includes the antibody in situ within recombinant cells, because at least one component of the antibody's natural environment will not be present. Ordinarily, however, isolated antibody will be prepared by at least one purification step.

[0163] "Purified" means that the antibody or functional fragment thereof is substantially free of cellular material or other contaminants originating from the cell or tissue source from which it is derived, or free from chemical precursors or other chemicals when chemically synthesized. The language includes preparations of the antibody in which the antibody is separated from the cellular components of the cells from which it is isolated or recombinantly produced. Thus, an antibody that is substantially free of cellular material includes preparations of the antibody having less than about 30%, 20%, 10%, or 5% (by dry weight) of contaminating protein and medium. In some embodiments, the antibody can be purified by chromatography, e.g., size exclusion chromatography or ion exchange chromatography.

[0164] As used herein, the term "complementarity determining region" (CDR, i.e., CDR1, CDR2, and CDR3) refers to amino acid residues of an antibody variable domain that are necessary for antigen binding. Each variable domain generally has three CDR regions identified as CDR1, CDR2, and CDR3. The CDRs of a variable heavy chain can be CDR-H1, CDR-H2, and CDR-H3. The CDRs of a variable light chain can be CDR-L1, CDR-L2, and CDR-L3. Exemplary hypervariable loops occur at amino acid residues 26-32 (L1), 50-52 (L2), 91-96 (L3), 26-32 (H1), 53-55 (H2), and 96-101 (H3). (Chothia and Lesk, J. Mol. Biol. 196:901-917 (1987)). Exemplary CDRs (CDR-L1, CDR-L2, CDR-L3, CDR-H1, CDR-H2, and CDR-H3) occur at amino acid residues 24-34 of L1, 50-56 of L2, 89-97 of L3, 31-35B of H1, 50-65 of H2, and 95-102 of H3 (Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed. (1991)). Thus, a HV can be contained within a corresponding CDR, and unless otherwise indicated, references herein to "hypervariable loops" of a VHand VLdomain are to be interpreted as also containing the corresponding CDRs, and vice versa. The more highly conserved regions of variable domains are called framework regions (FRs), as defined below. The variable domains of the heavy and light chains each comprise four FRs (FR1, FR2, FR3, and FR4), predominantly in the form of a [beta]-sheet conformation joined by three hypervariable loops. The hypervariable loops in each chain are held together and in relation to the CDRs from the other chain by the FRs, and contribute to the formation of the antigen binding site of antibodies. Structural analysis of antibodies reveals a relationship between the sequence and shape of the binding site formed by the CDRs (Chothia et al., J. Mol. Biol. 227:799-817 (1992)); Tramontano et al., J. Mol. Biol, 215:175-182 (1990)). Despite their high sequence variability, five of the six loops adopt only a small number of main-chain conformations, called "canonical structures." These conformations are determined primarily by the length of the loop, and secondarily by the presence of key residues at certain positions in the loop and framework regions, which determine the conformation by their packing, hydrogen bonding, or ability to adopt a unique main-chain conformation.

[0165] The “variable region” of an antibody refers to the variable region of either the light chain or the heavy chain, either alone or in combination. Each variable region of the heavy and light chains is composed of four frame regions (FRs) linked by three complementarity-determining regions (CDRs) (also known as hypervariable regions). The CDRs in each chain are held together very closely by the FRs and, together with the CDRs from the other chain, contribute to the formation of the antigen-binding site of the antibody. At least two techniques exist for determining CDRs: (1) methods based on cross-species sequence variability (i.e., Kabat et al., Sequences of Proteins of Immunological Interest, 5th edition, 1991, National Institutes of Health, Bethesda Md.); and (2) methods based on crystallographic studies of antigen-antibody complexes (Allazikani et al., 1997, J. Molec. Biol. 273: 927-948). A CDR can refer to a CDR defined by either method or a combination of both.

[0166] The "constant region" of an antibody refers to the constant region of the antibody light chain (i.e., the light chain constant region) or the constant region of the antibody heavy chain (i.e., the heavy chain constant region), whether alone or in combination. The constant region does not change with respect to antigen specificity.

[0167] As used herein, the term "heavy chain region" includes an amino acid sequence derived from an immunoglobulin heavy chain constant domain. A polypeptide comprising a heavy chain region comprises at least one of a CH1 domain, a hinge (e.g., upper hinge region, middle hinge region, and / or lower hinge region) domain, a CH2 domain, a CH3 domain, or a variant or fragment thereof. In one embodiment, an antibody or antigen-binding fragment thereof can comprise an Fc region of an immunoglobulin heavy chain (e.g., hinge portion, CH2 domain, and CH3 domain). In another embodiment, an antibody or antigen-binding fragment thereof lacks at least one region of a constant domain (e.g., all or part of a CH2 domain). In certain embodiments, at least one and preferably all of the constant domains are derived from a human immunoglobulin heavy chain. For example, in a preferred embodiment, the heavy chain region comprises a fully human hinge domain. In other preferred embodiments, the heavy chain region comprises a fully human Fc region (e.g., hinge, CH2 domain, and CH3 domain sequences from a human immunoglobulin). In certain embodiments, the constituent constant domains of the heavy chain region are from different immunoglobulin molecules. For example, the heavy chain region of a polypeptide can comprise a domain derived from an IgA molecule and a hinge region derived from an IgA1 molecule or an IgA2 molecule. In other embodiments, the constant domains are chimeric domains comprising regions of different immunoglobulin molecules. For example, a hinge can include a first region from an IgA1 molecule and a second region from an IgA2 molecule. As set forth above, one of ordinary skill in the art will appreciate that the constant domains of a heavy chain region can be modified such that they differ in amino acid sequence from naturally occurring (wild-type) immunoglobulin molecules. That is, the presently disclosed polypeptides can comprise alterations or modifications to one or more heavy chain constant domains (CH1, hinge, CH2, or CH3) and / or light chain constant domains (CL). Exemplary modifications include the addition, deletion, or substitution of one or more amino acids in one or more domains. In some embodiments, the modifications are selected from the modifications in Table 2.

[0168] An antibody or antigen-binding fragment thereof of the present disclosure can comprise a CDR3 region that is at least about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 amino acids in length. An antibody or antigen-binding fragment thereof of the present disclosure can comprise a CDR3 region that is at least about 18 amino acids in length.

[0169] As used herein, the term "hinge region" includes the region of a heavy chain molecule that connects the CH1 domain to the CH2 domain. The hinge region can comprise about 25 residues and is flexible, thereby allowing the two N-terminal antigen binding regions to move independently. The hinge region can be subdivided into three distinct domains: upper hinge, middle hinge, and lower hinge (Roux et al. J. Immunol. 1998 161 :4083).

[0170] As used herein, the term "Fv" is the minimum antibody fragment that contains a complete antigen recognition and binding site. This fragment consists of a dimer of one heavy and one light chain variable region domain in tight, non-covalent association.

[0171] The folding of the two domains generates six hypervariable loops (three loops from each of H and L chains), which contribute the amino acid residues for antigen binding, and impart antigen binding specificity to the antibody. However, even a single variable domain (or half of an Fv comprising only three antigen-specific CDRs) is sufficient for antigen recognition and binding, although at a lower affinity than the entire binding site.

[0172] A "heavy chain variable region" or "VH" with respect to an antibody refers to the fragment of the heavy chain that contains three CDRs interposed between flanking stretches called framework regions, which are generally more highly conserved than the CDRs and form a scaffold that supports the CDRs.

[0173] A "light chain variable region" or "VL" with respect to an antibody refers to the fragment of the light chain that contains three CDRs interposed between flanking stretches called framework regions, which are generally more highly conserved than the CDRs and form a scaffold that supports the CDRs.

[0174] The six hypervariable loops (three loops from each of H and L chains) contribute the amino acid residues for antigen binding, and impart antigen binding specificity to the antibody. However, even a single variable domain (or half of an Fv comprising only three antigen-specific CDRs) is sufficient for antigen recognition and binding, although at a lower affinity than the entire binding site.

[0175] "Framework" or FR residues are those variable domain residues other than the hypervariable region residues.

[0176] It is understood in the art that an antibody is a glycoprotein comprising at least two heavy chains (H) and two light chains (L) interconnected by disulfide bonds, or an antigen binding portion thereof. The heavy chains include a heavy chain variable region (VH) and a heavy chain constant region (CH1, CH2, and CH3). The light chains include a light chain variable region (VL) and a light chain constant region (CL). The variable regions of both the heavy and light chains comprise framework regions (FRs or FWRs) and hypervariable regions (HVRs). The HVRs are the amino acid residues in an antibody that are responsible for antigen binding. The hypervariable regions generally include amino acid residues from a complementarity determining region (CDR) with the highest sequence variability and / or involvement in antigen recognition. The CDRs generally include the amino acid residues that form the hypervariable loops, except for CDR1 in VH. The CDRs also include the "specificity determining residues" or "SDRs" which are residues that contact the antigen. The SDRs are contained within a region of the CDRs called abbreviated-CDRs or a-CDRs. Exemplary a-CDRs (a-CDR-L1, a-CDR-L2, a-CDR-L3, a-CDR-H1, a-CDR-H2, and a-CDR-H3) occur at amino acid residues 31-34 of L1, 50-55 of L2, 89-96 of L3, 31-35B of H1, 50-58 of H2, and 95-102 of H3 (see, e.g., Fransson, Front. Biosci. 13: 1619-1633 (2008)).

[0177] Unless otherwise indicated, HVR residues and other residues in the variable domains (e.g., FR residues) are numbered herein according to Rabat et al. (supra). A variable region is the domain of an antibody heavy or light chain that is involved in binding the antibody to an antigen. (See, e.g., Kindt et al. Kuby Immunology, 6th ed., W.H. Freeman and Co., page 91 (2007)). A single VH domain or VL domain can be sufficient to confer antigen-binding specificity. Furthermore, antibodies that bind a particular antigen can be isolated using a VH domain or a VL domain from an antibody that binds the antigen to screen a library of complementary VL domains or VH domains, respectively. (See, e.g., Portolano et al. J. Immunol. 150:880-887 (1993); Clarkson et al. Nature 352:624-628 (1991)). The four FWR regions are generally more conserved, while the CDR regions (CDR1, CDR2, and CDR3) represent hypervariable regions, and are arranged from the NH2 terminus to the COOH terminus as follows: FWR1, CDR1, FWR2, CDR2, FWR3, CDR3, and FWR4. The variable regions of both heavy and light chains contain a binding domain that interacts with an antigen, while the constant regions can mediate the binding of the immunoglobulin to host tissues or factors, depending on the isotype. Antibodies also include chimeric antibodies, humanized antibodies, and recombinant antibodies, human antibodies produced from transgenic non-human animals, and antibodies selected from libraries using enrichment techniques available to the skilled artisan.

[0178] The term "antibody heavy chain" refers to the larger of the two types of polypeptide chains found in an antibody molecule in its naturally occurring conformation, and an antibody heavy chain generally determines the class of the antibody.

[0179] The term "antibody light chain" refers to the smaller of the two types of polypeptide chains found in an antibody molecule in its naturally occurring conformation. Kappa ("K") and lambda ("l") light chains refer to the two major antibody light chain isotypes.

[0180] If an antibody or its antigen-binding fragment binds to a target with greater affinity and / or avidity than it binds to an epitope on an unrelated polypeptide, then the antibody or its antigen-binding fragment is “specifically bound” or “preferentially bound” to the target. The specificity of an antibody or its antigen-binding fragment or a portion thereof can be determined based on affinity and / or avidity. Methods for determining such specific binding are also well known in the art. According to certain embodiments of this disclosure, an antibody or its antigen-binding fragment may bind to human cancer antigens but not to cancer antigens from other species. Optionally, in some embodiments, an antibody or its antigen-binding fragment binds to human cancer antigens and cancer antigens from one or more non-human species. For example, an antibody or its antigen-binding fragment may bind to human cancer antigens and, depending on the specific circumstances, may bind to or not bind to cancer antigens from one or more of the following: mice, rats, guinea pigs, hamsters, gerbils, pigs, cats, dogs, rabbits, goats, sheep, cattle, horses, camels, cynomolgus monkeys, marmosets, rhesus monkeys, or chimpanzees.

[0181] The dissociation equilibrium constant (K) between antigen and antigen-binding protein D Affinity, expressed as K, is a measure of the strength of binding between an antigenic determinant and an antigen-binding site on an antigen-binding protein. D The smaller the value, the stronger the binding strength between the antigen determinant and the antigen-binding molecule. Alternatively, affinity can also be expressed as the affinity constant (K). A ), which is 1 / K D Those skilled in the art will understand that affinity can be determined, by methods known per se, based on the specific antigen of interest. Therefore, the affinity of an antibody or its antigen-binding fragment, as defined herein, for binding to a first target or antigen (as described above, and appropriately expressed as, for example, K) is considered. D An antibody or its antigen-binding fragment is considered "specific" to a first target or antigen when its affinity for the amino acid sequence or polypeptide is at least 50 times, such as at least 100 times, and preferably at least 1000 times, and up to 10,000 times or more, greater than that for a second target or antigen. Preferably, when an antibody or its antigen-binding fragment is "specific" to a target or antigen compared to another target or antigen, the antibody or its antigen-binding fragment can bind to that target or antigen but not to another target or antigen. However, as those skilled in the art will understand, in some embodiments where the binding site on the target is shared or partially shared by multiple different ligands, the antibody or its antigen-binding fragment can specifically bind to the target (such as a cancer-associated antigen) and have, for example, a functional effect of inhibiting / preventing tumor progression.

[0182] In some embodiments, the antibodies provided herein have concentrations of about 1 μM, 100 nM, 10 nM, 5 nM, 2 nM, 1 nM, 0.5 nM, 0.1 nM, 0.05 nM, 0.01 nM, or 0.001 nM or less (e.g., 10 μM). -8 M or smaller, for example, 10 -8 M to 10 -13 M, for example, 10 -9 M to 10 -13 The dissociation constant (K) of M) D Another aspect of the invention provides antibodies or antigen-binding fragments thereof that have increased affinity for their targets, for example, affinity-matured antibodies. Affinity-matured antibodies are antibodies with one or more alterations in one or more hypervariable regions (HVRs), which, compared to parental antibodies without such alterations, result in improved affinity of the antibody for the antigen. These affinity-matured antibodies are capable of binding at approximately 5 × 10⁻⁶. -9 M, 2×10 -9 M, 1×10 -9 M, 5×10 -10 M, 2×10 -10 M, 1×10 -10 M, 5×10 -11 M, 1×10 -11 M, 5×10 -12 M, 1×10 -12 M or smaller K D Binding to antigens. In some embodiments, this disclosure provides an antibody or antigen-binding fragment thereof that has an increased affinity of at least 1.5-fold, 2-fold, 2.5-fold, 3-fold, 4-fold, 5-fold, 10-fold, 20-fold, or higher compared to a WT IgA antibody or WT IgG antibody comprising a heavy chain sequence and a light chain sequence or both. In other embodiments, the antibody or functional fragment thereof provided herein competes with a corresponding antibody derived from a variable domain for binding to the same epitope. In some embodiments, antibodies or antigen-binding fragments thereof that bind to the same epitope with an antibody and / or compete with an antibody for binding to the same epitope exhibit effector functional activities, such as, for example, Fc-mediated cytotoxicity, including ADCC activity.

[0183] K D It can be measured by any suitable determination. For example, K DIt can be measured by radiolabeled antigen binding assay (RIA) (see, for example, Chen et al., J. Mol. Biol. 293:865-881 (1999); Presta et al., Cancer Res. 57:4593-4599 (1997)). For example, KD can be measured using surface plasmon resonance (e.g., using... or To measure. For example, K D Competitive ELISA can be used for measurement.

[0184] Affinity is a measure of the strength of binding between an antigen-binding molecule and its associated antigen. Affinity is related to the affinity between antigenic determinants and antigen-binding sites on the antigen-binding molecule, as well as the number of associated binding sites present on the antigen-binding molecule. Typically, antigen-binding proteins are expressed with respect to their dissociation constant (10⁻⁶). -5 Up to 10 -12 mol / L or less, and preferably 10 -7 Up to 10 -12 mol / L or less, and more preferably 10 -8 Up to 10 -12 moles / liter of K D (that is, with 10) 5 Up to 10 12 liters per mole or greater, and preferably 10 7 Up to 10 12 liters per mole or greater, and more preferably 10 8 Up to 10 12 Binding constant (K) per liter / molar A It binds to its homologous antigens or specific antigens. Any antigen greater than 10 -4 moles / liter of K D Value (or anything below 10) 4 M -1 K A The K-value is generally considered to indicate nonspecific binding. A meaningful (e.g., specific) K-value for biological interactions is considered... D Usually in 10 -10 M(0.1nM) to 10 -5 Within the range of M (10000nM). The stronger the interaction, the greater its K. DThe lower the better. Preferably, the binding site on the anti-LAP antibody or antigen-binding fragment thereof described herein will bind with an affinity of less than 500 nM, preferably less than 200 nM, more preferably less than 10 nM, such as less than 500 pM. Specific binding of an antigen-binding protein to an antigen or antigenic determinant can be determined in any suitable method known per se, including, for example, Scatchard analysis and / or competitive binding assays, such as radioimmunoassays (RIA), enzyme immunoassays (EIA) and sandwich competition assays, as well as different variants thereof known per se in the art; as well as other techniques mentioned herein.

[0185] As used herein, the term "k on " is intended to refer to the rate constant of association of an antibody or antigen-binding fragment thereof with an antigen.

[0186] As used herein, the term "K off " is intended to refer to the rate constant of dissociation of an antibody or antigen-binding fragment thereof from an antibody / antigen complex.

[0187] As used herein, the term "recombinant human antibody" includes all human antibodies that are prepared, expressed, created or isolated by recombinant means, such as (a) antibodies isolated from an animal (e.g., a mouse) that is transgenic or transchromosomal for human immunoglobulin genes or a hybridoma prepared therefrom (described further below), (b) antibodies isolated from a host cell transformed to express human antibody, e.g., from a transfectoma, (c) antibodies isolated from a recombinant, combinatorial human antibody library, and (d) antibodies prepared, expressed, created or isolated by any other means that involve splicing of human immunoglobulin gene sequences to other DNA sequences. Such recombinant human antibodies, as disclosed herein, have variable regions in which the framework and CDR regions are derived from immunoglobulin sequences. In certain embodiments, however, such recombinant human antibodies can be subjected to in vitro mutagenesis (or, when a transgenic animal carrying human Ig sequences is used, in vivo somatic mutagenesis), and thus the amino acid sequences of the VH and VL regions of the recombinant antibodies are sequences that, while derived from and related to human immunoglobulin VH and VL sequences, are not naturally occurring in the human antibody germline library.

[0188] The term "specificity" or "specific for" in the context of an antibody or antigen-binding fragment thereof refers to the number of different types of antigens or antigenic determinants to which a particular antibody or antigen-binding fragment thereof is capable of binding. The specificity of an antibody or antigen-binding fragment or portion thereof can be determined on the basis of affinity and / or avidity. The affinity of an antigen-binding protein for an antigen or antigenic determinant can be determined by the dissociation equilibrium constant (Kd) of the antigen-binding protein for the antigen. The Kd is the dissociation constant of the antigen-binding protein for the antigen, and is the ratio of the dissociation rate constant (koff) to the association rate constant (kon) of the antigen-binding protein for the antigen. The Kd is determined by measuring the rate of dissociation of the antigen-binding protein from the antigen at various concentrations of the antigen-binding protein, and is calculated by the equation:D Affinity, expressed as K, is a measure of the strength of binding between an antigenic determinant and an antigen-binding site on an antigen-binding protein. D The smaller the value, the stronger the binding strength between the antigenic determinant and the antigen-binding molecule. Alternatively, affinity can also be expressed as the affinity constant (K). A ), which is 1 / K D Those skilled in the art will understand that affinity can be determined, by methods known per se, based on the specific antigen of interest. Therefore, the affinity of an antibody or its antigen-binding fragment, as defined herein, for binding to a first target or antigen (as described above, and appropriately expressed as, for example, K) is considered. D An antibody or its antigen-binding fragment is considered "specific" to a first target or antigen when its affinity for the amino acid sequence or polypeptide is at least 50 times, such as at least 100 times, and preferably at least 1000 times, and up to 10,000 times or more, greater than that of the affinity of the amino acid sequence or polypeptide for binding to another target or polypeptide. Preferably, when an antibody or its antigen-binding fragment is "specific" to a target or antigen compared to another target or antigen, the antibody or its antigen-binding fragment can bind to that target or antigen but not to the other target or antigen.

[0189] However, as those skilled in the art will understand, in some embodiments, where the binding site on the target is shared or partially shared by multiple different ligands, the antibody or its antigen-binding fragment can specifically bind to the target antigen and have, for example, a functional effect of inhibiting / preventing tumor progression.

[0190] Affinity is a measure of the strength of binding between an antigen-binding molecule and its associated antigen. Affinity is related to the affinity between antigenic determinants and antigen-binding sites on the antigen-binding molecule, as well as the number of associated binding sites present on the antigen-binding molecule. Typically, antigen-binding proteins are expressed with respect to their dissociation constant (10⁻⁶). -5 Up to 10 -12 mol / L or less, and preferably 10 -7 Up to 10 -12 mol / L or less, and more preferably 10 -8 Up to 10 -12 moles / liter of K D (that is, with 10) 5 Up to 10 12 liters per mole or greater, and preferably 10 7 Up to 10 12 liters per mole or greater, and more preferably 10 8 Up to 10 12 Binding constant (K) per liter / molar A It binds to its homologous antigens or specific antigens. Any antigen greater than 10 -4 moles / liter of KD Values (or any values below 10 4 M -1 of K A values) are generally considered to indicate non-specific binding. K D values for biologic interactions that are considered meaningful (e.g., specific) are generally in the range of 10 -10 M (0.1 nM) to 10 -5 M (10000 nM). The stronger the interaction, the lower its K D Preferably, the binding site on the anti-LAP antibody or antigen-binding fragment thereof described herein will bind with an affinity of less than 500 nM, preferably less than 200 nM, more preferably less than 10 nM, such as less than 500 pM. Specific binding of an antigen-binding protein to an antigen or antigenic determinant can be determined in any suitable method known per se, including, for example, Scatchard analysis and / or competitive binding assays, such as radioimmunoassays (RIA), enzyme immunoassays (EIA) and sandwich competition assays, as well as different variants thereof known per se in the art; as well as other techniques mentioned herein.

[0191] The term "fusion protein" as used herein refers to a polypeptide comprising an amino acid sequence of an antibody or fragment thereof and an amino acid sequence of a heterologous polypeptide (i.e., an unrelated polypeptide).

[0192] In some embodiments, the antibody or antigen-binding fragment thereof of the present disclosure is a single domain antibody. The expression“single domain antibody” (sdAb) or“single variable domain (SVD) antibody” generally refers to a single variable region (VH or VL) in which antibody-antigen binding can be conferred. In other words, a single variable domain does not require interaction with another variable region to recognize a target antigen. Single domain antibody monomers bind antigen with a single arm per antibody variable region (VH*VJ combination). Examples of single domain antibodies include those derived from camelid (camels and llamas) and cartilaginous fish (e.g., nurse sharks) antibodies as well as those from human and mouse antibodies by recombinant methods (Ward et al., Nature (1989) 341 :544-546; Dooley and Flajnik, Dev Comp Immunol (2006) 30:43-56; Muyldermans et al., Trend Biochem Sci (2001) 26:230-235; Holt et al. Trends Biotechnol (2003): 21 :484-490; W02005 / 035572; TO 03 / 035694; Davies and Riechmann, Febs Lett (1994) 339:285-290; W000 / 29 004; WO 02 / 051870), and the single variable region of the antibody can be different from the single domain antibody variable region, or the variable domains are present in antigen binding arms (e.g., homomultimers or heteromultimers together).

[0193] As used herein, the term“modification” refers to an amino acid substitution or an amino acid deletion in one or more amino acid residues in the antibody heavy chain constant region compared to the WT heavy chain constant region of a WT antibody. In some embodiments, the modification is in an amino acid residue in the IgA CH1 region of the heavy chain constant region. In some embodiments, the modification is in an amino acid residue in the IgA CH2 region of the heavy chain constant region. In some embodiments, the modification is in an amino acid residue in the IgA CH3 region of the heavy chain constant region. In some embodiments, the modification is selected from Table 2. In some embodiments, one or more modifications disclosed herein result in an improvement in a property of the antibody comprising the one or more modifications compared to the corresponding WT antibody.

[0194] The term "improved property" means a property associated with an antibody comprising one or more modifications disclosed herein that is improved as compared to the parent WT antibody that does not comprise the one or more modifications. Such improved properties include, but are not limited to, increased thermal stability, increased circulating half-life, increased ADCC, decreased aggregation, decreased aggregation with serum proteins, increased tumor targeting, increased stability, decreased glycosylation, increased binding to FcaR expressed on immune cells. In some embodiments, the improved property is an increase in one or more effector functions of the antibody or functional fragment thereof as compared to the corresponding WT IgA. Effector functions are biological activities attributable to the Fc region of an antibody, which differs with antibody isotype. Examples of antibody effector functions include: Clq binding and complement dependent cytotoxicity (CDC); Fc receptor binding; antibody-dependent cell-mediated cytotoxicity (ADCC); phagocytosis.

[0195] In some embodiments, the antibodies or functional fragments thereof disclosed herein (e.g., comprising one or more modifications in the IgA heavy chain constant region disclosed herein) have at least 2%, 3%, 4%, 5%, 7%, 8%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or at least 100% of one or more improved properties as compared to the corresponding WT IgA antibody or the corresponding WT IgG antibody.

[0196] As used herein, the term "corresponding" unmodified antibody means a wild-type antibody that is identical to the antibody sequence comprising one or more selected modifications disclosed herein, but without one or more selected modifications described herein, particularly in the heavy chain constant region. In some embodiments, the corresponding antibody can be a WT IgA antibody comprising a WT IgA heavy chain constant region. In some embodiments, the corresponding antibody can be a WT IgG antibody comprising a WT IgG heavy chain constant region. In some embodiments, the corresponding WT IgA antibody is a WT IgA1 antibody. In some embodiments, the corresponding WT IgA antibody is a WT IgA2 antibody. In some embodiments, the corresponding WT IgA antibody comprises a wild-type IgA heavy chain constant region comprising the amino acid sequence set forth in SEQ ID NO: 1. In some embodiments, the corresponding WT IgA2 antibody comprises a wild-type IgA2 heavy chain constant region comprising the amino acid sequence set forth in SEQ ID NO: 1. In some embodiments, the corresponding WT IgA antibody comprises a wild-type IgA heavy chain constant region comprising the amino acid sequence set forth in SEQ ID NO: 2. In some embodiments, the corresponding WT IgA antibody comprises a wild-type IgA heavy chain constant region comprising the amino acid sequence set forth in SEQ ID NO: 2. In some embodiments, the WT IgA heavy chain constant region comprises the amino acid sequence set forth in SEQ ID NO: 1. In some embodiments, the WT IgA2 heavy chain constant region comprises the amino acid sequence set forth in SEQ ID NO: 1. In some embodiments, the amino acid modifications disclosed herein are relative to the amino acid residues at the selected positions in a WT IgA heavy chain constant region (e.g., a WT IgA2 heavy chain constant region) comprising the amino acid sequence set forth in SEQ ID NO: 1, numbered according to the IMGT scheme.

[0197] In some embodiments, the WT IgA heavy chain constant region comprises the amino acid sequence set forth in SEQ ID NO: 2. In some embodiments, the WT IgA2 heavy chain constant region comprises the amino acid sequence set forth in SEQ ID NO: 2. In some embodiments, the amino acid modifications disclosed herein are relative to the amino acid residues at the selected positions in a WT IgA heavy chain constant region (e.g., a WT IgA2 heavy chain constant region) comprising the amino acid sequence set forth in SEQ ID NO: 2, numbered according to the IMGT scheme.

[0198] In some embodiments, the WT IgA heavy chain constant region contains the amino acid sequence listed in SEQ ID NO:3. In some embodiments, the WT IgA2 heavy chain constant region contains the amino acid sequence listed in SEQ ID NO:3. In some embodiments, the amino acid modifications disclosed herein are amino acid residues at selected positions relative to the WT IgA heavy chain constant region containing the amino acid sequence listed in SEQ ID NO:3 (e.g., the WT IgA2 heavy chain constant region), numbered according to the IMGT scheme.

[0199] As used herein, the term "Fab" is intended to refer to a region of an antibody (a monovalent antigen-binding fragment) containing one constant domain and one variable domain for each heavy and light chain, but in which the heavy chain is truncated, resulting in the absence of the CH2 and CH3 domains (i.e., VH, CH1, VL, and CL), and possibly some or all of the hinge region. Fab can be produced by digesting the entire antibody with papain. Fab can refer to this region alone, or in the context of a full-length antibody, an immunoglobulin construct, or a Fab fusion protein.

[0200] As used herein, the term Fab' can be obtained by treating the entire antibody with pepsin and then reducing it to produce a molecule consisting of a complete light chain and a heavy chain portion containing a VH and a single constant domain. Each antibody treated in this way yields two Fab' fragments.

[0201] "scFv" refers to an antibody fragment containing both the VH and VL domains of an antibody, where these domains are present within a single polypeptide chain. See, for example, U.S. Patents 4,946,778, 5,260,203, 5,455,030, and 5,856,456. Typically, Fv polypeptides also contain a polypeptide linker between the VH and VL domains, which allows the scFv to form the structure required for antigen binding. For a review of scFv, see Pluckthun (1994), *The Pharmacology of Monoclonal Antibodies*, Vol. 113, eds. Rosenburg and Moore (Springer-Verlag, New York), pp. 269-315. The VH and VL domain complex of an Fv fragment can also be stabilized by disulfide bonds (U.S. Patent 5,747,654).

[0202] As used herein, the terms “in vivo half-life” or “circulating half-life” refer to the circulation of an antibody or a functional fragment thereof in a particular animal and are expressed as the time required for half of the amount administered to the animal to be cleared from circulation.

[0203] The term "increased circulating half-life" as used herein means that an antibody comprising one or more modifications relative to a WT IgA antibody provided according to the application has greater persistence and / or takes a longer period of time to reduce to half of the maximum measured serum or plasma concentration relative to the same antibody that does not comprise the same modification (i.e., a WT antibody, e.g., a WT IgA antibody) in serum or plasma.

[0204] The term "increased thermal stability" means a higher retention of biological activity (e.g., ADCC, binding to antigen, binding to FcaR) of an antibody or functional fragment disclosed herein relative to the corresponding WT IgA antibody after incubation at a temperature for a period of time. Increased thermal stability can be evaluated, for example, under conditions of one or more (e.g., several) temperatures. For example, the one or more (e.g., several) temperatures can be any temperature or a temperature in the range of 45 °C to 95 °C, e.g., 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, or 95 °C (or therebetween, e.g., 62 °C, 68 °C, 72 °C, etc.), at one or more (e.g., several) pH in the range of 3 to 9, e.g., 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, or 9.0 (or therebetween), for a suitable incubation period of time (time), e.g., 1 minute, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 45 minutes, or 60 minutes (or therebetween, e.g., 23 minutes, 37 minutes, etc.), such that the variant retains residual activity. However, longer incubation periods of time can also be used. The term "increased thermal stability" can be used interchangeably with "improved thermal stability."

[0205] As used herein, the term "naturally occurring" when it refers to a glycosylation site or an amino acid residue in an IgA heavy chain constant region refers to the fact that the glycosylation site or the amino acid residue can be found in an IgA heavy chain constant region in nature, e.g., can be isolated from a source in nature and has not been intentionally modified in the laboratory by a human (including a virus). A polypeptide or polynucleotide sequence that is found in an organism is a naturally occurring sequence.

[0206] The terms “disease,” “disorder,” or “condition” are used interchangeably in this text to refer to any alteration in the state of the body or organs, interruption or interference with the performance of functions, and / or symptoms in the person afflicted or in contact with the person, such as discomfort, dysfunction, pain, or even death. Disease or disorder can also be associated with fever, ailing, ailment, malady, disorder, sickness, illness, complaint, or affectation.

[0207] When used in the context of therapeutic or preventative treatment, the term "having a corresponding need" means having a disease, being diagnosed with a disease, or needing to prevent a disease, for example, for someone at risk of developing a disease. Therefore, a subject with a corresponding need can be a subject who needs treatment or prevention for a disease.

[0208] As used herein, the term "administration" means placing a compound (e.g., an antibody or antigen-binding fragment thereof, as disclosed herein) into a subject by a method or route that results in at least partial delivery of the agent at a desired site. Pharmaceutical compositions comprising antibodies or antigen-binding fragments thereof disclosed herein may be administered via any appropriate route that results in effective treatment in a subject, including but not limited to intravenous, intra-arterial injection, or direct infusion into tissue parenchyma. Where necessary or desired, administration may include, for example, intraventricular (“ICV”) administration, intranasal administration, intracranial administration, intracerebellar administration, or intrathecal administration.

[0209] The term "cancer" refers to a disease characterized by the rapid and uncontrolled growth of abnormal cells. Cancer cells can spread locally or to other parts of the body via the bloodstream and lymphatic system.

[0210] The term "antitumor effect" refers to biological effects that can be manifested through various means, including but not limited to: reduction in tumor volume, reduction in the number of tumor cells, reduction in the number of metastases, increase in life expectancy, reduction in tumor cell proliferation, reduction in tumor cell survival, or improvement in various physiological symptoms associated with cancerous conditions. The "antitumor effect" can also be manifested through the ability of the peptides, polynucleotides, cells, and antibodies of the present invention to prevent tumorigenesis.

[0211] As used herein, the terms "subject," "patient," "individual," and the like are used interchangeably and refer to a vertebrate, a mammal, a primate, or a human. Mammals include, but are not limited to, humans, primates, rodents, wild or domesticated animals, including feral animals, farm animals, sport animals, and pets. Primates include, for example, chimpanzees, cynomolgus monkeys, spider monkeys, and macaques, e.g., rhesus macaques. Rodents include, for example, mice, rats, woodchucks, ferrets, rabbits, and hamsters. Domesticated and game animals include, for example, cattle, horses, pigs, deer, bison, buffalo, feline species such as domestic cats, and canine species such as dogs, foxes, wolves, avian species (e.g., chickens, emus, ostriches), and fish (e.g., trout, catfish, and salmon). The terms "individual," "patient," and "subject" are used interchangeably herein. A subject can be male or female.

[0212] In some embodiments, a subject is a mammal. A mammal can be a human, a non-human primate, a mouse, a rat, a dog, a cat, a horse, or a cow, but is not limited to these examples. Mammals other than humans can advantageously be used as subjects that represent animal models of conditions or disorders associated with uncontrolled cell growth, e.g., cancer. Non-limiting examples include murine tumor models. In addition, the compositions and methods described herein can be used to treat domesticated animals and / or pets. A subject can be a subject previously diagnosed with or identified as suffering from a cancer. A subject can be a subject diagnosed with a particular disorder, e.g., cancer, and is currently being treated, or is seeking treatment, monitoring, adjustment, or modification of an existing therapeutic treatment, or is at risk of developing a particular disorder, e.g., cancer.

[0213] A "cytotoxic agent" refers to an agent that has a cytotoxic and / or cytostatic effect on cells. A "cytotoxic effect" refers to the depletion, elimination, and / or killing of target cells. A "cytostatic effect" refers to the inhibition of cell proliferation.

[0214] As used herein, the terms "protein," "peptide," and "polypeptide" are used interchangeably to refer to a series of amino acid residues connected to one another by peptide bonds between the alpha-amino groups and carboxyl groups of adjacent residues. The terms "protein," "peptide," and "polypeptide" refer to polymers of amino acids (including modified amino acids (e.g., phosphorylated amino acids, glycosylated amino acids, glycosylated amino acids, etc.) and amino acid analogs) regardless of their size or function. "Protein" and "polypeptide" are often used to refer to relatively larger polypeptides, while the term "peptide" is often used to refer to small polypeptides, although the use of these terms overlap in the art. The terms "protein," "peptide," and "polypeptide" are used interchangeably herein when referring to gene products and fragments thereof. These terms include, for example, natural and artificial proteins, protein fragments, and polypeptide analogs of protein sequences such as muteins, variants, and fusion proteins, as well as post-translationally modified proteins, or proteins that are otherwise covalently or non-covalently modified. A peptide, polypeptide, or protein can be monomeric or multimeric. A polypeptide can have an amino acid sequence from a naturally occurring polypeptide from any mammal. Such naturally occurring sequence polypeptides can be isolated from nature, or can be produced by recombinant or synthetic means. In some embodiments, a polypeptide is a "variant." By "variant" is meant a biologically active polypeptide that has at least about 80% amino acid sequence identity, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity, and not considering any conservative substitutions as part of the sequence identity. Such variants include, for example, polypeptides in which one or more amino acid residues are added or deleted at the N- or C-terminus of the polypeptide. In some embodiments, a variant will have at least about 80% amino acid sequence identity. In some embodiments, a variant will have at least about 90% amino acid sequence identity. In some embodiments, a variant will have at least about 95% amino acid sequence identity to a naturally occurring sequence polypeptide. A "derivative" of a polypeptide is a polypeptide (e.g., an antibody) that has been chemically modified, e.g., via conjugation to another chemical moiety such as, for example, polyethylene glycol or albumin, e.g., human serum albumin, phosphorylation, and glycosylation.

[0215] The terms "increased," "increase," or "enhance" are used herein generally to mean an increase by a statistically significant amount; for the avoidance of doubt, the terms "increased," "increase," or "enhance" mean an increase of at least 10% as compared to a reference level, e.g., an increase of at least about 10%, or at least about 20%, or at least about 30%, or at least about 40%, or at least about 50%, or at least about 60%, or at least about 70%, or at least about 80%, or at least about 90% as compared to a reference level, or an increase of up to and including 100%, or any increase between 10-100%, or an increase of at least about 2-fold, or at least about 3-fold, or at least about 4-fold, or at least about 5-fold, or at least about 10-fold, or any increase between 2-fold and 10-fold, or greater as compared to a reference level.

[0216] The term "fusion protein" as used herein refers to a polypeptide comprising the amino acid sequence of an antibody or fragment thereof and the amino acid sequence of a heterologous polypeptide (i.e., an unrelated polypeptide).

[0217] The terms "decrease," "reduce," "reduction," "lower," "lowering," or "inhibit" are used herein generally to mean a decrease by a statistically significant amount. For example, "decrease," "reduce," "reduction," or "inhibit" means a decrease of at least 10% as compared to a reference level, e.g., a decrease of at least about 20%, or at least about 30%, or at least about 40%, or at least about 50%, or at least about 60%, or at least about 70%, or at least about 80%, or at least about 90%, or up to and including 100% decrease (e.g., tumor size after treatment as compared to a reference level before treatment) or any decrease between 10-100%. In the context of a marker or symptom, these terms mean a statistically significant decrease in the level. The decrease can be, for example, at least 10%, at least 20%, at least 30%, at least 40% or more, and preferably down to a level within the normal range for an individual not afflicted with the particular disease. The decrease or inhibition can relate to, for example, the symptoms of the disorder being treated, the presence or size of metastases or micrometastases, the size of a primary tumor, the presence or size of dormant tumors.

[0218] The terms "synthetic polynucleotide," "synthetic gene," or "synthetic polypeptide" as used herein mean a corresponding polynucleotide sequence or portion thereof, or an amino acid sequence or portion thereof, that is derived from a sequence that has been designed or synthesized de novo or modified as compared to an equivalent naturally occurring sequence. Synthetic polynucleotides (antibodies or antigen binding fragments) or synthetic genes can be made by methods known in the art, including but not limited to chemical synthesis of nucleic acid sequences or amino acid sequences. Synthetic genes are typically different from naturally occurring genes at the amino acid level or the polynucleotide level (or both) and are typically in the context of synthetic expression control sequences. Synthetic gene polynucleotide sequences can not necessarily encode a protein with different amino acids as compared to a natural gene; for example, they can also include synthetic polynucleotide sequences that incorporate different codons but encode the same amino acids (i.e., nucleotide changes that represent silent mutations at the amino acid level).

[0219] IgA antibody

[0220] IgA has two subclasses (IgAl and IgA2) and can be produced in monomeric form as well as in dimeric and secreted forms. In some embodiments, the IgA antibody can be monomeric. In some embodiments, the IgA antibody can comprise one or more IgAl amino acid sequences. In some embodiments, the IgA antibody can comprise one or more IgA2 amino acid sequences. In some embodiments, the IgA antibody can comprise one or more IgAl amino acid sequences and one or more IgA2 amino acid sequences.

[0221] In some embodiments, the IgA antibody is an allotype IgA2 antibody: IgA2m(l), IgA2(m)2, or IgA2n. In some embodiments, the IgA2m(l) antibody is a Caucasian IgA2m(l) antibody. In some embodiments, the IgA2m(2) antibody is an African IgA2m(2) antibody or an Asian IgA2m(2) antibody.

[0222] In some embodiments, the IgA antibody comprises a heavy chain constant region comprising at least 60%, 70%, 75%, 80%, 85%, 90%, 95%, or 99% of IgA amino acids. In some embodiments, the IgA antibody comprises a light chain constant region comprising at least 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, or 99% of IgA amino acids.

[0223] In some embodiments, the IgA antibody comprises a heavy chain constant region comprising one or more of an IgA CH3 region, an IgA CH2 region, or an IgA CH1 region, or any combination thereof. In some embodiments, the IgA antibody comprises a light chain region comprising an IgA CH1 region. In some embodiments, the IgA antibody comprises a light chain region comprising a kappa light chain constant region. In some embodiments, the IgA antibody comprises a heavy chain constant region comprising one or more of the amino acids of an IgG CH3 region, an IgG CH2 region, or an IgG CH1 region, or any combination thereof. In some embodiments, the IgA antibody comprises a heavy chain constant region comprising an IgA CH3 region, an IgA CH2 region, and an IgA CH1 region, or any combination thereof. In some embodiments, the IgA antibody comprises a heavy chain constant region comprising an IgA CH3 region, an IgA CH2 region, and an IgG CH1 region, or any combination thereof. In some embodiments, the IgA2 antibody comprises a heavy chain constant region comprising one or more of an IgA2 CH3 region, an IgA2 CH2 region, or an IgA2 CH1 region, or any combination thereof.

[0224] In some embodiments, the IgA antibody comprises an IgG light chain variable region. In some embodiments, the IgA antibody comprises an IgG heavy chain variable region. In some embodiments, the IgA antibody comprises an IgG light chain variable region and an IgG heavy chain variable region.

[0225] In some embodiments, the IgA antibody can be a humanized antibody. In some embodiments, the IgA antibody can be a chimeric antibody. In some embodiments, the IgA antibody can be a human antibody.

[0226] In some embodiments, the IgA antibody can be a monospecific antibody. In some embodiments, the IgA antibody can be a bispecific antibody. In some embodiments, the IgA antibody can be a trispecific antibody. In some embodiments, the IgA antibody can be a multispecific antibody.

[0227] In some embodiments, the IgA antibody can be a bispecific antibody. In some embodiments, the IgA antibody co-engages two antigens at the cell surface. In some examples, the binding of the IgA antibody to the two different antigens is sequential. For example, the binding of the IgA antibody to the first antigen occurs first and thereby restricts the space explored by the second antibody arm. As a result, there can be a significant increase in the local concentration of the second antigen, which can facilitate the binding of the second antibody arm.

[0228] In some embodiments, the IgA antibody can comprise at least a portion of an Fc domain. In some embodiments, the IgA antibody comprises a heavy chain constant region comprising a CH3 domain, a CH2 domain, and a CH1 domain. In some embodiments, the IgA antibody comprises a light chain constant region comprising a CH1.

[0229] In some embodiments, the IgA antibody induces complement-dependent cytotoxicity (CDC). In some embodiments, the IgA antibody induces polymorphonuclear neutrophil (PMN)-mediated tumor cell lysis. In some embodiments, the IgA antibody induces programmed cell death (PCD) via a caspase-independent pathway. In some embodiments, the IgA antibody induces antibody-dependent cell-mediated cytotoxicity (ADCC). In some embodiments, the IgA antibody induces antibody-dependent cell-mediated cytotoxicity (ADCC) mediated by neutrophils.

[0230] In some embodiments, the IgA antibody can have a higher capacity to recruit neutrophils for antibody-dependent cell-mediated cytotoxicity (ADCC) compared to a corresponding IgG antibody. In some embodiments, the IgA antibody can require only a lower effector: target (E:T) ratio. In some embodiments, the IgA antibody can require only a lower tumor opsonizing antibody concentration compared to other types of antibodies (e.g., IgG). In some embodiments, the IgA antibody can trigger neutrophil-mediated phagocytosis or trogocytosis of tumor cells upon IgA antibody-neutrophil engagement. This mechanism of killing tumor cells is mediated primarily through interaction with the Fc receptor for IgA (FcαRI; CD89), which is the best characterized IgA receptor. FcαRI is expressed on monocytes, macrophages, granulocytes, dendritic cell subsets, and Kupffer cells, and binds both monomeric and dimeric IgA subclasses with moderate affinity. Binding of IgA to FcαRI mediates effector functions such as phagocytosis, oxidative burst, cytokine release, antigen presentation, and ADCC. In humans, two IgA isotypes, IgAl and IgA2, and three allotypes, IgA2m(l), IgA2m(2), and IgA2n, have been distinguished. In some embodiments, the IgA antibody is more effective than an IgG antibody in triggering polymorphonuclear cell (PMN)-mediated ADCC.

[0231] In some embodiments, IgA does not bind to B cells, T cells, platelets, and / or red blood cells. For example, in some embodiments, the IgA antibody can have low immunogenicity.

[0232] In some embodiments, the IgA antibody is a therapeutic antibody. In some embodiments, the IgA antibody can be a recombinant antibody. In some embodiments, the IgA antibody is made in a cell line. In some embodiments, the cell line is CHO. In some embodiments, the cell line is SP20. In some embodiments, the cell line is a HEK 239 cell line. In some embodiments, the HEK293 cell line is HEK 293F.

[0233] In some embodiments, the antibody or functional fragment thereof provided herein comprises an IgA heavy chain constant region having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 16-21. In some embodiments, the antibody or functional fragment thereof provided herein comprises a variable heavy chain domain from an IgG antibody. In some embodiments, the antibody or functional fragment thereof provided herein comprises a variable light chain domain from an IgG antibody. The variable domains can be derived from, for example, Dinutuximab, Obinutuzumab, Unituxin, TA99, 2.3D11, C47A8-CQ, UMAB10, and Trastuzumab and Rituxan (Rituximab), other antibodies within the scope of the present disclosure that have therapeutic activity include, but are not limited to, Avastin, Herceptin, 3F8, 8H9, Abagovomab, Ablciximab, Actoxumab, Adalimumab, Adecatumumab, Aducanumab, Afelimomab, Afutuzumab, Alacizumab pegol, ALD518, Alemtuzumab, Alirocumab, Altumomab pentetate, Amatuximab, Anatumomab mafenatox, Anifrolumab, Anrukinzumab, Apolizumab, Arcitumomab, Aselizumab, Atinumab, Atlizumab, Atorolimumab, Bapineuzumab, Basiliximab, Bavituximab, Bectumomab, Belimumab, Benralizumab, Bertilimumab, Besilesomab, Bevacizumab, Bezlotoxumab, Biciromab, Bimagrumab, Bivatuzumab mertansine, Blinatumomab, Blosozumab, Brentuximab,vedotin, Briakinumab, Brodalumab, Canakinumab, Cantuzumab mertansine, Cantuzumab ravtansine, Caplacizumab, Capromab pendetide, Carlumab, Catumaxomab, cBR96-doxorubicin immunoconjugate, CC49, Cedelizumab, Certolizumab pegol, Cetuximab, Ch.14.18, Citatuzumab bogatox, Cixutumumab, Clazakizumab, Clenoliximab, Clivatuzumab tetraxetan, Conatumumab, Concizumab, CR6261, Crenezumab, Dacetuzumab, Daclizumab, Dalotuzumab, Daratumumab, Demcizumab, Denosumab, Detumomab, Dorlimomab aritox, Drozitumab, Duligotumab, Dupilumab, Dusigitumab, Ecromeximab, Eculizumab, Edobacomab, Edrecolomab, Efalizumab, Efungumab, Eldelumab, Elotuzumab, Elsilimomab, Enavatuzumab, Enlimomab pegol, Enokizumab, Enoticumab, Ensituximab, Epitumomabcituxetan, Epratuzumab, Erlizumab, Ertumaxomab, Etaracizumab, Etrolizumab, Evolocumab, Exbivirumab, Fanolesomab, Faralimomab, Farletuzumab, Fasinumab, FBTA05, Felvizumab, Fezakinumab, Ficlatuzumab, Figitumumab, Flanvotumab, Fontolizumab, Foralumab, Foravirumab, Fresolimumab, Fulranumab, Futuximab, Galiximab, Ganitumab, Gantenerumab, Gavilimomab, Gemtuzumab ozogamicin, Gevokizumab, Girentuximab, Glembatumumab vedotin, Golimumab, Gomiliximab, Guselkumab, Ibalizumab, Ibritumomab tiuxetan, Icrucumab, Igovomab, IMAB362, Imciromab, Imgatuzumab, Inclacumab, Indatuximab ravtansine, Infliximab, Inolimomab, Inotuzumabozogamicin, intetumumab, ipilimumab, iratumumab, itolizumab, ixekizumab, keliximab, labetuzumab, lambrolizumab, lampalizumab, lebrikizumab, lelemosomab, lerdelimumab, lexatumumab, libivirumab, ligelizumab, lintuzumab, lirilumab, lodelcizumab, lorvotuzumab mertansine, lucatumumab, lumiliximab, mapatumumab, margetuximab, maslimomab, matuzumab, mavrilimumab, mepolizumab, metelimumab, milatuzumab, minretumomab, mitumomab, mogamulizumab, morolimumab, motavizumab, moxetumomab pasudotox, muromonab-CD3, nacolomab tafenatox, namilumab, naptumomab estafenatox, narnatumab, natalizumab, nebacumab, necitumumab, nerelimomab, nesvacumab, nimotuzumab, nivolumab, nofetumomab merpentan, ocaratuzumab, ocrelizumab, odulimomab, ofatumumab, olaratumab, olokizumab, omalizumab, onartuzumab, ontuxizumab, oportuzumab, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib, orantinib,monatox), Oregovomab, Orticumab, Otelixizumab, Otlertuzumab, Oxelumab, Ozanezumab, Ozoralizumab, Pagibaximab, Palivizumab, Panitumumab, Pankomab, Panobacumab, Parsatuzumab, Pascolizumab, Pateclizumab, Patritumab, Pemtumomab, Perakizumab, Pertuzumab, Pexelizumab, Pidilizumab, Pinatuzumab vedotin, Pintumomab, Placulumab, Polatuzumab vedotin, Ponezumab, Priliximab, Pritoxaximab, Pritumumab, PRO 140, Quilizumab, Racotumomab, Radretumab, Rafivirumab, Ramucirumab, Ranibizumab, Raxibacumab, Regavirumab, Reslizumab, Rilotumumab, Rituximab, Robatumumab, Roledumab, Romosozumab, Rontalizumab, Rovelizumab, Ruplizumab, Samalizumab, Sarilumab, Satumomabpendetide, Secukinumab, Seribantumab, Setoxaximab, Sevirumab, SGN-CD19A, SGN-CD33A, Sibrotuzumab, Sifalimumab, Siltuximab, Simtuzumab, Siplizumab, Sirukumab, Solanezumab, Solitomab, Sonepcizumab, Sontuzumab, Stamulumab, Sulesomab, Suvizumab, Tabalumab, Tacatuzumab tetraxetan, Tadocizumab, Talizumab, Tanezumab, Taplitumomab paptox, Tefibazumab, Telimomab aritox, Tenatumomab, Teneliximab, Teplizumab, Teprotumumab, TGN1412, Ticilimumab, Tigatuzumab, Tildrakizumab, TNX-650, Tocilizumab, Toralizumab, Tositumomab, Tovetumab, Tralokinumab, Trastuzumab, TRBS07, Tregalizumab, Tremelimumab, Tucotuzumab celmoleukin, Tuvirumab, Ublituximab, Urelumab, Urtoxazumab, Ustekinumab, Vantictumab, Vapaliximab, Vatelizumab, Vedolizumab, Veltuzumab, Vepalimomab, Vesencumab, Visilizumab, Volociximab, VorsetuzumabMafodotin, Votumumab, Zalutumumab, Zanolimumab, Zatuximab, Ziralimumab, hu14.18K322A, Zolimomab aritox, Rituximab (CD20) Trastuzumab (HER2) Alemtuzumab (CD52) Ibritumomab tiuxetan (CD20) Tositumomab-I-131 (CD20) Cetuximab (EGFR) Bevacizumab (VEGF) Panitumumab (EGFR) Ofatumumab (CD20) Ipilimumab (CTLA-4) Brentuximab vedotin (CD30) Pertuzumab (HER2) Adotrastuzumab, Ematansine (HER2) Ocaratuzumab (CD20) Nivolumab and Pembrolizumab (anti-PD-1)

[0234] In one aspect, the antibody or its antigen-binding fragment comprises a heavy chain variable region (VH) sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity with the amino acid sequence of any one of SEQ ID NO:4, SEQ ID NO:7, and SEQ ID NO:81-86. In some embodiments, the VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity comprises substitutions (e.g., conserved substitutions), insertions, or deletions relative to a reference sequence, but the antibody comprising this sequence retains the ability to bind the same antigen as a WT antibody. In some embodiments, a total of 1 to 10 amino acids in the amino acid sequence of any one of SEQ ID NO:4, SEQ ID NO:7, and SEQ ID NO:81-86 are substituted, inserted, and / or deleted. In some embodiments, substitution, insertion, or deletion occurs in regions outside the CDR (e.g., in the FR). Optionally, the antibody comprises a VH sequence of the amino acid sequences of SEQ ID NO:4, SEQ ID NO:7, and SEQ ID NO:81-86, including one or more post-translational modifications of that sequence. In a particular embodiment, the VH comprises one, two, or three CDRs selected from: (a) HC-CDR1 comprising any one of the amino acid sequences of SEQ ID NO:33-40, (b) HC-CDR2 comprising any one of the amino acid sequences of SEQ ID NO:41-48, and (c) HC-CDR3 comprising any one of the amino acid sequences of SEQ ID NO:49-56.

[0235] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a VL that has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NO: 5, SEQ ID NO: 8, SEQ ID NOs: 95-100. In some embodiments, a VL sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody or antigen-binding fragment thereof comprising that sequence retains the ability to bind the same antigen as the WT antibody. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of any one of SEQ ID NO: 5, SEQ ID NO: 8, SEQ ID NOs: 95-100. In some embodiments, the substitutions, insertions, or deletions occur in regions outside of the CDRs (e.g., in the FRs). Optionally, the antibody or antigen-binding fragment thereof comprises a VL sequence of any one of SEQ ID NO: 5, SEQ ID NO: 8, SEQ ID NOs: 95-100, including post-translational modifications of that sequence. In particular embodiments, the VL comprises one, two, or three CDRs selected from: (a) LC-CDR1 comprising the amino acid sequence of any one of SEQ ID NOs: 57-64; (b) LC-CDR2 comprising the amino acid sequence of any one of SEQ ID NOs: 65-72; and (c) LC-CDR3 comprising the amino acid sequence of any one of SEQ ID NOs: 73-80.

[0236] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a VL that has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NO: 5, SEQ ID NO: 8, SEQ ID NOs: 95-100. In some embodiments, a VL sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody or antigen-binding fragment thereof comprising that sequence retains the ability to bind the same antigen as the WT antibody. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of any one of SEQ ID NO: 5, SEQ ID NO: 8, SEQ ID NOs: 95-100. In some embodiments, the substitutions, insertions, or deletions occur in regions outside of the CDRs (e.g., in the FRs). Optionally, the antibody or antigen-binding fragment thereof comprises a VL sequence of any one of SEQ ID NO: 5, SEQ ID NO: 8, SEQ ID NOs: 95-100, including post-translational modifications of that sequence. In particular embodiments, the VL comprises one, two, or three CDRs selected from: (a) LC-CDR1 comprising the amino acid sequence of any one of SEQ ID NOs: 57-64; (b) LC-CDR2 comprising the amino acid sequence of any one of SEQ ID NOs: 65-72; and (c) LC-CDR3 comprising the amino acid sequence of any one of SEQ ID NOs: 73-80.

[0237] In one aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a VH selected from any of the VHs in Table 9. In one aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a VL selected from any of the VLs in Table 9. In one aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a VH selected from any of the VHs in Table 9 and a VL selected from any of the VLs in Table 9. In one aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a VH selected from any of the VHs in Table 9 and a VL selected from any of the VLs in Table 9, wherein the selected VH and VL are paired according to Table 9. In one aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a HC-CDR3 selected from any of the HC-CDR3s in Table 5 and a LC-CDR3 selected from any of the LC-CDR3s in Table 6, wherein the selected HC-CDR3 and LC-CDR3 are paired according to Table 9. In one aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a HC-CDR2 selected from any of the HC-CDR2s in Table 5 and a LC-CDR-2 selected from any of the LC-CDR-2s in Table 6, wherein the selected HC-CDR2 and LC-CDR2 are paired according to Table 9. In one aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a HC-CDR1 selected from any of the HC-CDR1s in Table 5 and a LC-CDR1 selected from any of the LC-CDR1s in Table 6, wherein the selected HC-CDR1 and LC-CDR1 are paired according to Table 9. In one aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a HC-CDR1, HC-CDR2, and HC-CDR3 selected from any of the HC-CDR1, HC-CDR2, and HC-CDR3s in Table 5, and a LC-CDR1, LC-CDR2, and LC-CDR3 selected from any of the LC-CDR1, LC-CDR2, and LC-CDR3s in Table 6, wherein the selected HC-CDR1, HC-CDR2, HC-CDR3, LC-CDR1, LC-CDR2, and LC-CDR3 are paired according to Table 9. In some embodiments, the antibody or antigen-binding fragment thereof comprises any one of a HC-CDR1, HC-CDR2, and HC-CDR3 selected from any of the HC-CDR1, HC-CDR2, and HC-CDR3s in Table 5 and any IgA heavy chain constant region selected from SEQ ID NOs: 16-21. In some embodiments, the antibody or antigen-binding fragment thereof comprises any one of a LC-CDR1, LC-CDR2, and LC-CDR3 selected from any of the LC-CDR1, LC-CDR2, and LC-CDR3s in Table 6 and any IgA heavy chain constant region selected from SEQ ID NOs: 16-21.

[0238] In some embodiments, the antibody or its antigen-binding fragment comprises any one of HC-CDR1, HC-CDR2, and HC-CDR3 selected from any HC-CDR1, HC-CDR2, and HC-CDR3 in Table 5, and any one of LC-CDR1, LC-CDR2, and LC-CDR3 selected from any LC-CDR1, LC-CDR2, and LC-CDR3 in Table 6, as well as any IgA heavy chain constant region selected from SEQ ID NO:16-21, wherein the selected HC-CDR1, HC-CDR2, HC-CDR3, selected LC-CDR1, LC-CDR2, LC-CDR3, and selected IgA heavy chain constant regions are paired according to Table 9.

[0239] IgA antibody modification

[0240] This article describes IgA antibodies containing one or more amino acid substitutions and / or one or more amino acid deletions.

[0241] In some embodiments, the amino acid numbering of the IgA antibodies described herein is indicated according to the IMGT unique numbering for C-DOMAIN and C-LIKE-DOMAIN (as disclosed in “IMGT unique numbering for immunoglobulin and T cell receptor constant domains and Ig superfamily C-like domains.” Dev Comp Immunol. 2005; 29(3): 185-203, the entire contents of which are incorporated herein by reference). In some embodiments, the amino acid modifications disclosed herein are numbered according to the IMGT scheme relative to the amino acid residues at selected positions in a WT IgA heavy chain constant region (e.g., a WT IgA2 heavy chain constant region) comprising the amino acid sequence set forth in SEQ ID NO: 1. It is noted that US 62 / 824,864, incorporated in its entirety herein, also includes antibodies and antibody constructs comprising modified IgA heavy chain constant regions numbered according to the IMGT numbering scheme. Some of the amino acids are inadvertently mislabeled, and the specific amino acid positions as described in US 62 / 824,864 correspond to the following specific amino acid positions as provided herein. The positions C92, N120, I121, and T122 as mentioned in US 62 / 824,864 correspond to the amino acid residues C86, N114, I115, and T116 in the antibodies described herein, which are correctly labeled according to the IMGT numbering scheme (IMGT numbering, depicted in Table 11, for reference position numbering only). The reference wild-type heavy chain constant region sequence of these antibodies as disclosed in US 62 / 824,864 and the present application is identical, i.e., SEQ ID NO: 1 as shown in Figure 1 Table 1. Thus, it would be apparent to the skilled artisan that residues C86, N114, I115, and T116 in the IMGT nomenclature scheme were inadvertently mislabeled as C92, N120, I121, and T122 in US 62 / 824,864.

[0242] In some embodiments, the IgA antibodies disclosed herein comprise a deletion of at least four glycosylation sites within the constant region. In some embodiments, the IgA antibodies disclosed herein comprise a deletion of at least three N-linked glycosylation sites in the antibody constant region. In some embodiments, the IgA antibodies comprise a deletion of at least three N-linked glycosylation sites in the antibody constant region and at least one O-linked glycosylation site in the antibody constant region. In some embodiments, the IgA antibodies or functional fragments disclosed herein comprise one or more modifications disclosed herein (e.g., Table 2) in the IgA heavy chain constant region. In some embodiments, the IgA antibodies or functional fragments disclosed herein comprise one or more modifications disclosed herein (e.g., Table 2) in the IgAl heavy chain constant region. In some embodiments, the IgA antibodies or functional fragments disclosed herein comprise one or more modifications disclosed herein (e.g., Table 2) in the IgA2 heavy chain constant region. In some embodiments, the one or more modifications are in amino acid residues within the CHI region, the CH2 region, and / or the CH3 region of the IgAl heavy chain constant region.

[0243] In some embodiments, the IgA antibody comprises a deleted tailpiece. In some embodiments, the one or more modifications are in amino acid residues within the CH1 region, the CH2 region, and / or the CH3 region of the IgA2 heavy chain constant region. In some embodiments, the IgA CH1 region comprises an amino acid sequence that is at least about 80%, 85%, 90%, 95%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 109. In some embodiments, the IgA CH3 region comprises an amino acid sequence that is at least about 80%, 85%, 90%, 95%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 110. In some embodiments, the IgA CH2 region comprises an amino acid sequence that is at least about 80%, 85%, 90%, 95%, 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO: 111. In some embodiments, the IgA antibody or functional fragment thereof as disclosed herein comprises a deletion of 3-20, 3-19, 3-18, 3-17, 3-16, 3-15, 3-14, 3-13, 3-12, 3-11, 3-10, 3-9, 3-8, 3-7, 3-6, 3-5, 3-4 C-terminal amino acids. In some embodiments, the IgA2 antibody comprises a deletion of 3-20, 3-19, 3-18, 3-17, 3-16, 3-15, 3-14, 3-13, 3-12, 3-11, 3-10, 3-9, 3-8, 3-7, 3-6, 3-5, 3-4 C-terminal amino acids. In some embodiments, the C-terminal amino acids are from amino acids 131-148 of the IgA2 antibody, numbered according to the IMGT scheme.

[0244] In some embodiments, the IgA2 antibody comprises a deletion of amino acids 131-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 147-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 146-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 145-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 144-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 143-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 142-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 141-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 140-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 139-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 138-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 137-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 136-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 135-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 134-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 133-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 132-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids 131-148, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acids P131-Y148, numbered according to the IMGT scheme.

[0245] In some embodiments, the IgA antibody comprises a mutation of the C-terminal asparagine (N) amino acid. In some embodiments, the mutation is a non-conservative amino acid substitution. In some embodiments, the mutation is a deletion of the glycosylation site of the C-terminal asparagine (N) amino acid of the IgA. In some embodiments, the IgA2 antibody comprises a mutation of N135, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a non-conservative mutation of N135, numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a N135Q mutation, numbered according to the IMGT scheme.

[0246] In some embodiments, the IgA antibody or functional fragment thereof disclosed herein comprises a modification in at least two naturally occurring glycosylation sites in the IgA heavy chain constant region. In some embodiments, the IgA antibody or functional fragment thereof disclosed herein comprises a modification in at least three naturally occurring glycosylation sites in the IgA heavy chain constant region. In some embodiments, the IgA antibody or functional fragment thereof disclosed herein comprises a modification in at least four naturally occurring glycosylation sites. In some embodiments, the glycosylation sites comprise N-linked glycosylation sites. In some embodiments, the glycosylation sites comprise naturally occurring asparagine residues. In some embodiments, the glycosylation sites are located in the CH2 region, the CH3 region, and / or the CH1 region. In some embodiments, the IgA heavy chain constant region comprises a modification at N45.2G, N15.2, L15.3, T16, N114, I115, T116, N135, or a combination thereof, numbered according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises an amino acid substitution of N45.2G, N45.2A, N15.2G, N15.2Q, N15.2T, L15.3I, T16S, N114T, I115L, T116S, N135Q, or a combination thereof, numbered according to the IMGT scheme. In some embodiments, provided herein is a non-glycosylated antibody or functional fragment thereof. In some embodiments, the non-glycosylated antibody comprises a modification at all four naturally occurring glycosylation sites in the IgA2 heavy chain constant region. In some embodiments, the non-glycosylated antibody provided herein comprises a modification at residues N45.2, N15.2, L15.3, T16, N114, I115, T116, and N135, numbered according to the IMGT scheme. In some embodiments, the non-glycosylated antibody provided herein comprises a modification at residues N45.2, N15.2, N114, I115, T116, and N135, numbered according to the IMGT scheme.

[0247] In some embodiments, the non-glycosylated antibody provided herein comprises modifications at residues N45.2, N15.2, L15.3, T16, N114, I115, T116, and N135, numbered according to the IMGT scheme, and a deletion of the C-terminal tail residues P131-Y148. In some embodiments, the non-glycosylated antibody provided herein comprises modifications at residues N45.2, N15.2, N114, I115, T116, and N135, numbered according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises amino acid substitutions N45.2G, N45.2A, N15.2G, N114T, I115L, T116S, and N135Q, numbered according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises amino acid substitutions N45.2G, N45.2A, N15.2Q, L15.3I, T16S, N114T, I115L, T116S, and N135Q. In some embodiments, the IgA heavy chain constant region comprises amino acid substitutions N45.2G, N45.2A, N15.2G, N15.2T, N114T, I115L, T116S, and N135Q, numbered according to the IMGT scheme. In some embodiments, the antibody comprising a combination of amino acid substitutions N45.2G, N45.2A, N15.2G, N15.2T, N114T, I115L, T116S, and N135Q in the IgA heavy chain constant region, numbered according to the IMGT scheme, is a non-glycosylated antibody. In some embodiments, the non-glycosylated antibody comprises a combination of amino acid substitutions N45.2G, N45.2A, N15.2G, T16S, N114T, I115L, T116S, and a deletion of the C-terminal tail.

[0248] In some embodiments, the non-glycosylated antibody provided herein comprises modifications at residues N45.2, N15.2, L15.3, T16, N114, I115, T116, and N135, numbered according to the IMGT scheme, and a deletion of the C-terminal tail residues P131-Y148. In some embodiments, the non-glycosylated antibody provided herein comprises modifications at residues N45.2, N15.2, N114, I115, T116, and N135, numbered according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises amino acid substitutions N45.2G, N45.2A, N15.2G, N114T, I115L, T116S, and N135Q, numbered according to the IMGT scheme. In some embodiments, the IgA heavy chain constant region comprises amino acid substitutions N45.2G, N45.2A, N15.2Q, L15.3I, T16S, N114T, I115L, T116S, and N135Q. In some embodiments, the IgA heavy chain constant region comprises amino acid substitutions N45.2G, N45.2A, N15.2G, N15.2T, N114T, I115L, T116S, and N135Q, numbered according to the IMGT scheme. In some embodiments, the antibody comprising a combination of amino acid substitutions N45.2G, N45.2A, N15.2G, N15.2T, N114T, I115L, T116S, and N135Q in the IgA heavy chain constant region, numbered according to the IMGT scheme, is a non-glycosylated antibody. In some embodiments, the non-glycosylated antibody comprises a combination of amino acid substitutions N45.2G, N45.2A, N15.2G, T16S, N114T, I115L, T116S, and a deletion of the C-terminal tail.

[0249] In some embodiments, the antibody comprising a combination of amino acid substitutions in the IgA heavy chain constant region of N45.2G, N45.2A, N15.2Q, N114T, I115L, T116S, and N135Q, numbered according to the IMGT scheme, is a non-glycosylated antibody. In some embodiments, the non-glycosylated antibody comprises a combination of amino acid substitutions of N45.2G, N45.2A, N15.2Q, T16S, N114T, I115L, T116S, and a deletion of the C-terminal tailpiece. In some embodiments, the antibody comprising a combination of amino acid substitutions in the IgA heavy chain constant region of N45.2G, N45.2A, N15.2T, N114T, I115L, T116S, and N135Q, numbered according to the IMGT scheme, is a non-glycosylated antibody. In some embodiments, the non-glycosylated antibody comprises a combination of amino acid substitutions of N45.2G, N45.2A, N15.2T, T16S, N114T, I115L, T116S, and a deletion of the C-terminal tailpiece. In some embodiments, the antibody comprising a combination of amino acid substitutions in the IgA heavy chain constant region of N45.2G, N45.2A, N15.2T, L15.3I, T16S, N114T, I115L, T116S, and N135Q, numbered according to the IMGT scheme, is a non-glycosylated antibody. In some embodiments, the non-glycosylated antibody comprises a combination of amino acid substitutions of N45.2G, N45.2A, N15.2T, L15.3I, T16S, T16S, N114T, I115L, T116S, and a deletion of the C-terminal tailpiece.

[0250] In some embodiments, the non-glycosylated antibody exhibits increased circulating half-life relative to a corresponding antibody or a corresponding WT IgA antibody comprising at least one glycosylation site (e.g., WT residue N45.2, N114, N15.2, and N135 numbered according to the IMGT scheme). In some embodiments, the non-glycosylated antibody exhibits decreased aggregation relative to a corresponding antibody or a WT IgA antibody comprising at least one glycosylation site (e.g., WT residue N45.2, N114, N15.2, and N135 numbered according to the IMGT scheme). In some embodiments, the non-glycosylated antibody exhibits decreased aggregation with serum proteins relative to a corresponding antibody or a corresponding WT IgA antibody comprising at least one glycosylation site (e.g., WT residue N45.2, N114, N15.2, and N135 numbered according to the IMGT scheme). In some embodiments, the non-glycosylated antibody exhibits decreased aggregation relative to a corresponding antibody or a corresponding WT IgA antibody comprising at least one glycosylation site (e.g., WT residue N45.2, N114, N15.2, and N135 numbered according to the IMGT scheme). In some embodiments, the non-glycosylated antibody exhibits increased thermal stability relative to a corresponding WT IgA. In some embodiments, the non-glycosylated antibody exhibits increased binding affinity to an Fc receptor relative to a corresponding WT IgA. In some embodiments, the non-glycosylated antibody induces ADCC against a target cell. In some embodiments, the non-glycosylated antibody specifically binds to a target antigen. In some embodiments, the non-glycosylated antibody specifically binds to a target cell.

[0251] In some embodiments, the antibody comprises a mutation of N45.2 numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a non-conservative mutation of N45.2 numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises N45.2G numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody has increased circulating half-life compared to an IgA2 antibody that does not have a mutation of the N45.2 amino acid.

[0252] In some embodiments, the antibody comprises a mutation of P124 numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a non-conservative mutation of P124 numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises P124R numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody has increased circulating half-life compared to an IgA2 antibody that does not have a mutation of the P124 amino acid. In some embodiments, the IgA2 antibody has increased stability compared to an IgA2 antibody that does not have a mutation of the P124 amino acid.

[0253] In some embodiments, the antibody as described herein comprises a mutation of C86 numbered according to the IMGT scheme (referred to as C92 in US 62 / 824,864, which is incorporated in its entirety herein, inadvertently as described above). In some embodiments, the antibody comprises a non-conservative mutation of C86 numbered according to the IMGT scheme. In some embodiments, the antibody comprises C86S numbered according to the IMGT scheme. In some embodiments, the antibody has reduced aggregation compared to an antibody that does not have a mutation of the C86 amino acid. In some embodiments, the antibody has reduced aggregation with serum proteins compared to an antibody that does not have a mutation of the C86 amino acid. In some embodiments, the antibody has reduced aggregation in vitro or in vivo compared to an antibody that does not have a mutation of the C86 amino acid.

[0254] In some embodiments, the IgA2 antibody comprises a mutation of C86 according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a non-conservative mutation of C86 numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises C86S numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody has reduced aggregation compared to an IgA2 antibody that does not have a mutation of the C86 amino acid. In some embodiments, the IgA2 antibody has reduced aggregation with serum proteins compared to an IgA2 antibody that does not have a mutation of the C86 amino acid. In some embodiments, the IgA2 antibody has reduced aggregation in vitro or in vivo compared to an IgA2 antibody that does not have a mutation of the C86 amino acid.

[0255] In some embodiments, the antibody comprises a mutation of N114 numbered according to the IMGT scheme (referred to as N120 in US 62 / 824,864, which is incorporated in its entirety herein, inadvertently as described above). In some embodiments, the antibody comprises a non-conservative mutation of N114 numbered according to the IMGT scheme. In some embodiments, the antibody comprises N114T numbered according to the IMGT scheme. In some embodiments, the antibody has increased circulating half-life compared to an IgA2 antibody that does not have a mutation of the N114 amino acid.

[0256] In some embodiments, the antibody comprises a mutation of N114 according to the IMGT numbering scheme. In some embodiments, the antibody comprises a non-conservative mutation of N114 according to the IMGT numbering scheme. In some embodiments, the antibody comprises N14T according to the IMGT numbering scheme. In some embodiments, the IgA2 antibody has an increased circulating half-life compared to an IgA2 antibody that does not have a mutation of the N114 amino acid.

[0257] In some embodiments, the antibody comprises a mutation of T116 according to the IMGT numbering scheme. In some embodiments, the antibody comprises a non-conservative mutation of T116 according to the IMGT numbering scheme. In some embodiments, the antibody comprises T116S according to the IMGT numbering scheme. In some embodiments, the IgA2 antibody has an increased circulating half-life compared to an IgA2 antibody that does not have a mutation of the T116 amino acid.

[0258] In some embodiments, the IgA2 antibody comprises a mutation of N114 according to the IMGT numbering scheme. In some embodiments, the IgA2 antibody comprises a non-conservative mutation of N114 according to the IMGT numbering scheme. In some embodiments, the IgA2 antibody comprises N14T according to the IMGT numbering scheme. In some embodiments, the IgA2 antibody has an increased circulating half-life compared to an IgA2 antibody that does not have a mutation of the N114 amino acid.

[0259] In some embodiments, the IgA2 antibody comprises a mutation of I115 according to the IMGT numbering scheme. In some embodiments, the IgA2 antibody comprises a non-conservative mutation of I115 according to the IMGT numbering scheme. In some embodiments, the IgA2 antibody comprises I115L according to the IMGT numbering scheme. In some embodiments, the IgA2 antibody has an increased circulating half-life compared to an IgA2 antibody that does not have a mutation of the I115 amino acid.

[0260] In some embodiments, the IgA2 antibody comprises a mutation of T116 according to the IMGT numbering scheme. In some embodiments, the IgA2 antibody comprises a non-conservative mutation of T116 according to the IMGT numbering scheme. In some embodiments, the IgA2 antibody comprises T116S according to the IMGT numbering scheme. In some embodiments, the IgA2 antibody has an increased circulating half-life compared to an IgA2 antibody that does not have a mutation of the T116 amino acid.

[0261] In some embodiments, the IgA2 antibody comprises a mutation of N15.2 according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a non-conservative mutation of N15.2 numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises N15.2G, N15.2Q, or N15.2T according to the IMGT scheme numbering. In some embodiments, the IgA2 antibody has an increased circulating half-life compared to an IgA2 antibody that does not have a mutation of the N15.2 amino acid.

[0262] In some embodiments, the IgA2 antibody comprises a mutation of L15.3 according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a non-conservative mutation of L15.3 numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises L15.3I according to the IMGT scheme numbering. In some embodiments, the IgA2 antibody has an increased circulating half-life compared to an IgA2 antibody that does not have a mutation of the L15.3 amino acid.

[0263] In some embodiments, the IgA2 antibody comprises a mutation of T16 according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a non-conservative mutation of T16 numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises T16S according to the IMGT scheme numbering. In some embodiments, the IgA2 antibody has an increased circulating half-life compared to an IgA2 antibody that does not have a mutation of the T16S amino acid.

[0264] In some embodiments, the IgA2 antibody comprises a mutation of C147 according to the IMGT scheme numbering. In some embodiments, the IgA2 antibody comprises a non-conservative mutation of C147 numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acid C147 according to the IMGT scheme numbering. In some embodiments, the IgA2 antibody has a decreased aggregation compared to an IgA2 antibody that does not have a mutation of the C147 amino acid.

[0265] In some embodiments, the IgA2 antibody comprises a mutation of Y148 according to the IMGT scheme numbering. In some embodiments, the IgA2 antibody comprises a non-conservative mutation of Y148 numbered according to the IMGT scheme. In some embodiments, the IgA2 antibody comprises a deletion of amino acid Y148 according to the IMGT scheme numbering.

[0266] In some embodiments, the IgA antibody comprises one or more albumin binding domains. In some embodiments, the one or more albumin binding domains are fused to a light chain or a heavy chain of the IgA constant region. In some embodiments, the one or more albumin binding domains are fused to a heavy chain of the IgA constant region. In some embodiments, the one or more albumin binding domains are fused to a C-terminal region of a CH3 region of a heavy chain of the IgA constant region. In some embodiments, the IgA2 antibody has an increased circulating half-life compared to an IgA2 antibody that does not comprise one or more albumin binding domains. In some embodiments, the IgA2 antibody comprises one or more albumin binding domains and has a circulating half-life that is within 1%, 5%, or 10% of the circulating half-life of a corresponding IgG antibody. In some embodiments, the IgA2 antibody comprises one or more albumin binding domains and has a circulating half-life that is greater than the circulating half-life of a corresponding IgG antibody.

[0267] In some embodiments, the IgA antibody comprises one or more mutations described in Lohse S. et al. Cancer Res. 2015; 76(2):403-17; Meyer S. et al. mAbs. 2016; 8(1):87-98; or Leusen J. et al. Molecular Immunology. 2015; 68:35-39.

[0268] In some embodiments, the one or more mutations or deletions result in an increase or decrease in the circulating half-life of the IgA antibody. In some embodiments, the one or more mutations or deletions result in an increase in the circulating half-life of the IgA antibody. For example, the one or more mutations can increase the serum half-life of the IgA antibody in humans up to 21 days or more. In addition, the one or more mutations can increase the serum half-life of the IgA antibody in mice up to 9 days or more. In some embodiments, the one or more mutations can increase the serum half-life of the IgA antibody to a level comparable to the serum half-life of an immunoglobulin G (IgG) molecule. In some embodiments, the one or more mutations or deletions result in a decrease in the circulating half-life of the IgA antibody.

[0269] In some embodiments, the one or more mutations can increase the serum half-life of the IgA antibody by at least about 7 days to about 30 days or more. In some embodiments, the one or more mutations can increase the serum half-life of the IgA antibody by at least about 7 days. In some embodiments, the one or more mutations can increase the serum half-life of the IgA antibody by at most about 30 days. In some embodiments, the one or more mutations can increase the serum half-life of the IgA antibody by about 7 days to about 8 days, about 7 days to about 9 days, about 7 days to about 10 days, about 7 days to about 15 days, about 7 days to about 20 days, about 7 days to about 25 days, about 7 days to about 30 days, about 8 days to about 9 days, about 8 days to about 10 days, about 8 days to about 15 days, about 8 days to about 20 days, about 8 days to about 25 days, about 8 days to about 30 days, about 9 days to about 10 days, about 9 days to about 15 days, about 9 days to about 20 days, about 9 days to about 25 days, about 9 days to about 30 days, about 10 days to about 15 days, about 10 days to about 20 days, about 10 days to about 25 days, about 10 days to about 30 days, about 15 days to about 20 days, about 15 days to about 25 days, about 15 days to about 30 days, about 20 days to about 25 days, about 20 days to about 30 days, or about 25 days to about 30 days. In some embodiments, the one or more mutations can increase the serum half-life of the IgA antibody by about 7 days, about 8 days, about 9 days, about 10 days, about 15 days, about 20 days, about 25 days, or about 30 days. Thus, in some embodiments, the antibodies or functional fragments thereof disclosed herein exhibit a longer circulating half-life compared to the corresponding WT IgA antibody. In some embodiments, the antibody exhibits a circulating half-life that is at least about 2%, 5%, 10%, 12%, 15%, 20%, 25%, 50%, 65%, 70%, 75%, 85%, 90%, 95%, 99%, 100%, 150%, and 200% greater relative to the corresponding WT IgA antibody.

[0270] In some embodiments, the IgA antibody exhibits increased stability. In some embodiments, the one or more mutations and / or one or more deletions result in increased stability of the IgA antibody compared to the corresponding IgA antibody that does not comprise the one or more mutations and / or one or more deletions.

[0271] In some embodiments, the IgA antibody exhibits reduced aggregation. Antibody aggregation is a more common manifestation of physical instability. Protein aggregates generally have reduced activity, and more importantly, greater immunogenic potential due to multiplicity of epitopes and / or conformational changes. Immunoglobulin aggregates are known to cause severe renal failure and anaphylactic reactions such as headache, fever, and chills. Thus, it is advantageous to reduce aggregation in antibody therapeutics. Furthermore, according to the World Health Organization (WHO) standards, aggregate levels of commercial intravenous immunoglobulin products are limited to less than 5%. In some embodiments, the one or more mutations result in reduced aggregation. In some embodiments, the one or more mutations and / or one or more deletions result in reduced aggregation of the IgA antibody compared to the corresponding IgA antibody that does not comprise the one or more mutations and / or one or more deletions. In some embodiments, the antibody or functional fragment thereof disclosed herein exhibits reduced aggregation compared to the corresponding WT IgA antibody. In some embodiments, the antibody exhibits at least about 2%, at least 5%, at least 10%, at least 12%, at least 15%, at least 20%, at least 25%, at least 50%, at least 65%, at least 70%, at least 75%, at least 85%, at least 90%, at least 95%, at least 99%, at least 100%, at least 150%, and at least 200% less aggregation relative to the corresponding WT IgA antibody. In some embodiments, the antibody or functional fragment thereof disclosed herein exhibits reduced aggregation with serum proteins compared to the corresponding WT IgA antibody. In some embodiments, the antibody exhibits at least 2%, at least 5%, at least 10%, at least 12%, at least 15%, at least 20%, at least 25%, at least 50%, at least 65%, at least 70%, at least 75%, at least 85%, at least 90%, at least 95%, at least 99%, at least 100%, at least 150%, and at least 200% less aggregation relative to the corresponding WT IgA antibody.

[0272] In some embodiments, the IgA antibodies provided herein have an aggregate level ranging from at least about 0.1% to at most about 5%. In some embodiments, the IgA antibodies provided herein have an aggregate level ranging from at least about 0.1%. In some embodiments, the IgA antibodies provided herein have an aggregate level ranging from at most about 5%. In some embodiments, the IgA antibodies provided herein have an aggregate level ranging from about 0.1% to about 0.5%, about 0.1% to about 1%, about 0.1% to about 2%, about 0.1% to about 3%, about 0.1% to about 4%, about 0.1% to about 5%, about 0.5% to about 1%, about 0.5% to about 2%, about 0.5% to about 3%, about 0.5% to about 4%, about 0.5% to about 5%, about 1% to about 2%, about 1% to about 3%, about 1% to about 4%, about 1% to about 5%, about 2% to about 3%, about 2% to about 4%, about 2% to about 5%, about 3% to about 4%, about 3% to about 5%, or about 4% to about 5%. In some embodiments, the IgA antibodies provided herein have an aggregate level ranging from about 0.1%, about 0.5%, about 1%, about 2%, about 3%, about 4%, or about 5%.

[0273] The therapeutic antibodies disclosed herein can comprise synthetic amino acids in place of one or more naturally occurring amino acids. Such synthetic amino acids are known in the art and include, for example, aminocyclohexane carboxylic acid, norleucine, alpha-amino normal decanoic acid, homoserine, S-acetylamino methyl-cysteine, trans-3-hydroxyproline and trans-4-hydroxyproline, 4-aminophenylalanine, 4-nitrophenylalanine, 4-chlorophenylalanine, 4-carboxyphenylalanine, beta-phenylserine, beta-hydroxyphenylalanine, phenylglycine, alpha-naphthylalanine, cyclohexylalanine, cyclohexylglycine, dihydroindole-2-carboxylic acid, 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid, aminomalonic acid, aminomalonic acid monoamide, N'-benzyl-N'-methyl- lysine, N',N'-dibenzyl-lysine, 6-hydroxylysine, ornithine, alpha-aminocyclopentane carboxylic acid, alpha-aminocyclohexane carboxylic acid, alpha-aminocycloheptane carboxylic acid, alpha-(2-amino-2-norbornane)-carboxylic acid, alpha, gamma-diaminobutyric acid, alpha, beta-diaminopropionic acid, homophenylalanine, and alpha-tert-butylglycine.

[0274] Methods of substituting or deleting amino acids are known in the art. For example, amino acid substitutions or deletions can be accomplished by site-directed mutagenesis (e.g., Zoller and Smith Nucl. Acids Res. 10:6487 (1982)). Mutagenesis can be performed by synthesizing oligonucleotides having one or more modifications within the constant domain sequence of the antibody to be modified. Antibodies of the present disclosure (e.g., comprising one or more modifications in the IgA heavy chain constant region) can be made using any mutagenesis procedure known in the art, such as site-directed mutagenesis, synthetic gene construction, semi-synthetic gene construction, random mutagenesis, shuffling, and the like. Site-directed mutagenesis allows for the production of mutants by using specific oligonucleotide sequences that encode the desired mutation, and a sufficient number of adjacent oligonucleotides to provide primer sequences of sufficient size and sequence complexity to form stable duplexes on both sides of the deletion junction being traversed. Typically, primers of about 17 to about 75 nucleotides or more in length are preferred, about 10 to about 25 or more residues on both sides of the junction of the sequence being altered. A number of such primers can be used to introduce a variety of different mutations at one or more positions to produce a library of mutants.

[0275] Site-directed mutagenesis techniques are known in the art (see, e.g., Kunkel et al., Methods Enzymol., 154:367-82, 1987). Typically, site-directed mutagenesis is performed by first obtaining a single-stranded vector or unzipping the two strands of a double-stranded vector, which contains a DNA sequence encoding a desired peptide in its sequence. An oligonucleotide primer carrying the desired mutant sequence is prepared, usually synthetically. The primer is then annealed to the single-stranded vector and subjected to a DNA polymerase, such as T7 DNA polymerase, to complete the synthesis of the mutant-bearing strand. A heteroduplex is thereby formed, in which one strand encodes the original, non-mutant sequence, and the second strand carries the desired mutation. The heteroduplex vector is then used to transform or transfect suitable cells, such as E. coli cells, and clones containing recombinant vectors carrying the mutant sequence arrangement are selected. As will be appreciated, this technique typically employs bacteriophage vectors that exist in both single-stranded and double-stranded forms. Typical vectors that can be used for site-directed mutagenesis include vectors such as M13 bacteriophage. These bacteriophages are readily commercially available, and their use is generally well known to those skilled in the art. Double-stranded plasmids are also routinely used for site-directed mutagenesis, which eliminates the step of transferring the gene of interest from a plasmid to a bacteriophage. Site-directed mutagenesis has also been used to identify amino acid residues that affect plasma clearance of murine IgGl hinge-Fc fragments, as described in Kim Jin-Kyoo et al. (1994) Eur. J. Immunol. 24:542-548).

[0276] Alternatively, the use of PCR performed by commercially available thermostable enzymes, such as Taq DNA polymerase, can be used to incorporate mutagenic oligonucleotide primers into the amplified DNA fragment, which can then be cloned into a suitable cloning or expression vector. For PCR-mediated mutagenesis procedures, see, e.g., Tomic et al., Nucleic Acids Res., 18(6):1656, 1987, and Upender et al., Biotechniques, 18(1):29-30, 32, 1995. In addition to thermostable polymerases, PCR employing thermostable ligases can also be used to incorporate phosphorylated mutagenic oligonucleotides into the amplified DNA fragment, which can then be cloned into a suitable cloning or expression vector (see, e.g., Michael, Biotechniques, 16(3):410-2, 1994).

[0277] Other methods known to those skilled in the art for generating sequence variants of the Fc region of an antibody or FcR binding domain thereof can be used. For example, a recombinant vector encoding the amino acid sequence of a constant domain of an antibody or fragment thereof can be treated with a mutagenic agent, such as hydroxylamine, to obtain sequence variants. Mutants that result in a desired property (e.g., increased ADCC, decreased aggregation, increased affinity for an FcR, and / or increased half-life in vivo) can be screened using routine assays, such as those described below.

[0278] Synthetic gene construction requires in vitro synthesis of a designed polynucleotide molecule encoding a polypeptide of interest. Gene synthesis can be performed using a number of techniques, such as the multiplexed microchip-based technology described by Tian et al. (2004, Nature 432:1050-1054) in which oligonucleotides are synthesized and assembled on a light-programmable microfluidic chip, and similar technologies. Single or multiple amino acid substitutions, deletions, and / or insertions can be made and tested using known methods in the art, such as mutagenesis, recombination, and / or shuffling, followed by appropriate screening procedures (such as those described by Reidhaar-Olson and Sauer, 1988, Science 241 :53-57; Bowie and Sauer, 1989, Proc. Natl. Acad. Sci. USA 86:2152-2156; WO 95 / 17413; or WO 95 / 22625). Other methods that can be used include error-prone PCR, phage display (e.g., Lowman et al., 1991, Biochemistry 30:10832-10837; U.S. Patent No. 5,223,409; WO 92 / 06204), and region-directed mutagenesis (Derbyshire et al., 1986, Gene 46:145; Ner et al., 1988, DNA 7:127).

[0279] Mutagenesis / shuffling methods can be combined with high-throughput automated screening methods to detect the activity of cloned, mutagenized polypeptides expressed in host cells (Ness et al., 1999, Nature Biotechnology 17:893-896). The mutagenized DNA molecules that encode active polypeptides can be recovered from the host cells and rapidly sequenced using standard methods in the art. These methods allow the rapid determination of the importance of individual amino acid residues in the polypeptide.

[0280] Hemisynthetic gene construction is accomplished by combining aspects of synthetic gene construction, and / or site-directed mutagenesis, and / or random mutagenesis, and / or shuffling. A typical feature of hemisynthetic construction is a process that utilizes synthetic polynucleotide fragments in conjunction with PCR techniques. Thus, specific regions of a gene can be synthesized de novo, while other regions can be amplified using site-specific mutagenic primers, while yet other regions can undergo error-prone or non-error prone PCR amplification. The polynucleotide subsequences can then be shuffled.

[0281] Other covalent modifications

[0282] Covalent modifications of antibodies are also included within the scope of this invention. Covalent modifications of the antibody, if applicable, can be performed by chemical synthesis or by enzymatic or chemical cleavage of the antibody. Other types of covalent modifications of the antibody introduce molecules into the antibody by reacting a targeted amino acid residue of the antibody with an organic derivatizing agent that is capable of reacting with selected side chains or the N- or C-terminal residues.

[0283] Cysteine residues most typically are reacted with haloacetic acids (and corresponding amines) such as chloroacetic acid or chloroacetic amide to provide carboxymethyl or carboxyamidomethyl derivatives. Cysteine residues also are derivatized by reaction with bromotrifluoropropanone, alpha-bromo-(5 imidozoyl) propionic acid, chloroacetyl phosphate, N-alkylmaleimides, 3-nitro-2-pyridyl disulfide, methyl 2-pyridyl disulfide, p-chloromercuribenzoate, 2-chloromercuri-4-nitrophenol, or chloro-7-nitrobenz-2-oxa-1,3-diazole.

[0284] Histidine residues are derivatized by reaction with diethyl pyrocarbonate at pH 5.5-7.0, since this reagent is relatively specific for the histidine side chain. Para-bromophenacyl bromide is also useful; the reaction is preferably performed in 0.1 M sodium diethyldithiocarbamate at pH 6.0. Lysine and amino terminal residues are reacted with succinic or other carboxylic acid anhydrides. Derivatization with these agents has the effect of reversing the charge on the lysine residue. Other suitable reagents for derivatizing amino-containing residues include imidoesters such as methyl picolinimidate, pyridoxal phosphate, pyridoxal, chloroborohydride, trinitrophenylsulfonic acid, methyl isourea, 2,4-pentanedione, and transaminase-catalyzed reaction with glyoxylate.

[0285] Arginyl residues are modified by reaction with one or several of the common reagents, including phenylglyoxal, 2,3-butanedione, 1,2-cyclohexanedione, and indanetrione. Because of the high pKa of the guanidine function, derivatization of arginine residues requires that the reaction be carried out under basic conditions. In addition, these reagents can react with lysine groups as well as with arginine ε-amino groups.

[0286] Particular modification of tyrosyl residues is often desirous, particularly the introduction of spectroscopic labels into tyrosyl residues by reaction with aromatic diazonium compounds or tetranitromethane. Most commonly, N-acetylimidazole and tetranitromethane are used to form O-acetyl tyrosyl species and 3-nitro derivatives, respectively. Tyrosyl residues are iodinated using 125I or 131I to prepare labeled proteins for use in radioimmunoassays. Selective O-phosphorylation of the hydroxyl groups of seryl or threonyl residues is often used experimentally to stabilize proteins against degradation, since seryl and threonyl residues tend to be cleaved in proteins. Carboxyl side groups (aspartyl or glutamyl) are selectively modified by reaction with carbodiimides (R-N=C=N-R'), where R and R' are different alkyl groups, such as l-cyclohexyl-3-(2-morpholin-4-ethyl) carbodiimide or l-ethyl-3-(4-azonia-4,4-dimethylpentyl) carbodiimide. In addition, aspartyl and glutamyl residues are converted to asparagine and glutamine residues, respectively, by reaction with ammonium ions.

[0287] Glutamine and asparagine residues are frequently deamidated to the corresponding glutamic acid and aspartic acid residues, respectively. These deamidation reactions occur when the -CO-NH2 side chain group is adjacent to a carboxylic acid (-COOH) or a carbonyl moiety in the peptide backbone. The deamidation of asparagines and glutamine residues also falls within the scope of this invention. Other modifications include hydroxylation of proline and lysine, phosphorylation of hydroxyl groups of seryl or threonyl residues, methylation of the alpha-amino groups of lysine, arginine, and histidine side chains (T. E. Creighton, Proteins: Structure and Molecular Properties, W. H. Freeman & Co., San Francisco, pp. 79-86 (1983)), acetylation of the N-terminal amine, and amide formation from any C-terminal carboxylic acid group.

[0288] Another type of covalent modification comprises the conjugation of glycosides chemically or enzymatically to antibodies. These procedures have the advantage that they do not require production of the antibody in a host cell having glycosylation capability for N-linked or O-linked glycosylation. Depending on the mode of conjugation used, sugars can be attached to (a) arginine and histidine, (b) free carboxyl groups, (c) free sulfhydryl groups such as those of cysteine, (d) free hydroxyl groups such as those of serine, threonine, or hydroxyproline, (e) aromatic residues such as those of phenylalanine, tyrosine, or tryptophan, or (f) the amide group of glutamine. These methods are described in WO 87105330, published September 11, 1987, and Aplin and Wriston, CRC Crit. Rev. Biochem., pp. 259-306 (1981).

[0289] Removal of any carbohydrate moieties present on the antibody can be accomplished chemically or enzymatically. Chemical deglycosylation requires exposure of the antibody to the compound trifluoromethanesulfonic acid or an equivalent compound. This treatment results in the cleavage of most or all sugars except the linking sugar (N-acetylglucosamine or N-acetylgalactosamine) with the antibody remaining intact. Chemical deglycosylation is described by Hakimuddin et al. Arch. Biochem. Biophys. 259:52 (1987) and by Edge et al. Anal. Biochem., 118:131 (1981). Enzymatic cleavage of carbohydrate moieties on antibodies can be achieved by the use of various endoglycosidases and exoglycosidases as described by Thotakura et al. Meth. Enzymol. 138:350 (1987).

[0290] Another type of covalent modification of the antibody comprises linking the antibody to one of various nonproteinaceous polymers, e.g., polyethylene glycol, polypropylene glycol, polyoxyethylated polyols, polyoxyethylated sorbitol, polyoxyethylated glucose, polyoxyethylated glycerol, polyoxyalkylenes, or sugar polymers such as dextran. Such methodologies are known in the art, see, e.g., U.S. Pat. Nos. 4,640,835; 4,496,689; 4,301,144; 4,670,417; 4,791,192; 4,179,337; 4,766,106; 4,179,337; 4,495,285; 4,609,546; or EP 315 456.

[0291] IgA antibody targets

[0292] The IgA antibodies described herein can be used to target antigens expressed on the surface of a cell. In some embodiments, the IgA antibody comprises an antigen binding region that specifically binds to an antigen expressed on the surface of a target cell (e.g., a cancer cell). In some embodiments, the antigen is a human antigen. In some embodiments, the target cell is a human cell. In some embodiments, the IgA antibody comprises an antigen binding domain that specifically binds to an antigen of one of the following proteins: CD20, GD2, CD47, CD38, EGFR, HER2, PD-L1, CD25, CD33, BCMA, CD44, CD21, CD64, a-folate receptor, CAIX, CD30, ROR1, CEA, EGP-2, EGP-40, HER3, folate-binding protein, GD3, IL-13R-a2, KDR, EDB-F, mesothelin, EGFR, MUC-1, MAGE-A1, MUC16, h5T4, PSMA, TAG-72, EGFRvIII, CD123, VEGF-R2, BCMA, CD19, CD22, CD30, CD33, CD123, CD38, CD44, CD70, CD274, CD45, CD123, CD138, CD171, ROR1, EGFR, EphA2, FBP, FAP, CEA, EGP2, EGP40, TAG72, PSMA, PSA, PAP, hsp70-2, M-CSF, LAGE-la, p53, NKG2D ligand, B7-H6, IL-13Rα2, IL-11Rα, MUC1, MUC16, CA9, GD3, HMW-MAA, CD171, Lewis Y, G250 / CAIX, HLA-AIMAGE A1, HLA-A2 NY-ESO-1, PSC1, PCTA-1, MAGE, ELF2M, IGF-I, IGF-II, IGF-I receptor, hTERT, WT1, MUC1, LMP2, HPV16, HPV18, RGL4, MelanA, MART, ML-IAP, AFP, BCR, ABL, CYP1B1, PLAC1, BORIS, NY-BR-1, RGS5, SART3, EphA2, Glypican-3, 5T4, 8H9, ανβ6 integrin, B7-H3, B7-H6, CAIX, CA9, CSPG4, EGP2, EGP40, EPCAM, ERBB3, ERBB4, ErbB3 / 4, FAP, FAR, FBP, KDR, MCSP, Muc1, Muc16, NCAM, PRAME, ROR1, CD44v7 / 8, 8H9, NCAM, VEGF-R, TAG72, RAGE-1, MN-CAIX, RU1, RU2 (AS), fetal AchR, TEM1, TEM8, PAX5, OY-TES1, LCK, HMWMAA, AKAP-4, SSX2, XAGE 1, tie 2, PDGFR-beta, Kallikrein 4, PBF, PRAME, HSDL1, CA125, TADG-12, MUC16, Mannotriose-MIC-1, HERV-K-MEL, KK-LC-1, KM-HN-1, LAGE-1, MAGE-A4, SP17, SSX4, TAG1, TAG2, ENAH, mammaglobin-A, NY-BR-1, BAGE-1, HERV-K-MEL, KK-LC-1, KM-KN-1, LAGE1, MAGE1A, MAGEA2, mucink, TRAG3, c-myc, Cyclin B1, p62, DKK1, RU2AS, k-ras, ME1, NFYC, STEAP1, FGF5, RU2AS, hsp70-2, ARTC1, B-RAF, beta catenin, CDC27, CDK4, CDK12, CDKN2A, CLPP, CSNK1A1, FN1, GAS7, GPNMB, HAUS3, LDLR-fucosyltransferase, MART2, MATN, MUM1, MUM2, MUM3, neo-PAP, myosin, PPP1R3B, PRDX5, PTPRK, RBAF600, SIRT2, SNRPD1, Triosephosphate isomerase, OA1, RAB38, TRP1, TRP2, melan-A, BAGE1, GAGE1, GAGE2, GAGE8, GAGE3, GAGE4, GAGE5, GAGE6, GAGE7, GNTVF, LY6K, TRAG3, CASP8, SAGE, DEK-CAN, EFTUD2, FLT3-ITD, Cyclin A1, FNDC3B, MAGEAG, G250, hepsin, intestinal carboxylesterase, PBF, CASP5, COA1, OGT, OS9, CALCA, MDM2, alpha-actinin 4, elongation factor 2, fos-related antigen 1, legumain, sperm protein 17, carbonic anhydrase IX, folate receptor-alpha, neutrophil elastase, ephrinB2, glioma-associated antigen, beta-human chorionic gonadotropin, alpha-fetoprotein, thyroglobulin, telomerase reverse transcriptase, intestinal carboxylesterase, prostein, or survivin.

[0293] Ganglioside G2

[0294] In some embodiments, the IgA antibodies or functional fragments thereof disclosed herein (i.e., antibodies comprising one or more modifications disclosed herein in the IgA heavy chain constant region) specifically bind GD2. In some embodiments, the IgA antibodies bind O-acetylated GD2. In some embodiments, the IgA antibodies bind GD2, but not O-acetylated GD2. In some embodiments, the IgA antibodies bind O-acetylated GD2, but not GD2. In some embodiments, the antibodies bind GD2 and bind O-acetylated GD2. In some embodiments, the antibodies or functional fragments disclosed herein specifically bind human GD2 polypeptides. Polypeptides and encoding nucleic acid sequences of GD2 of human origin and of many animal origins are publicly available, e.g., available from the NCBI website.

[0295] In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of antibody ch14.18. In some embodiments, the IgA antibody comprises one, two, or three of CDR1, CDR2, or CDR3 of the heavy chain of antibody ch14.18. In some embodiments, the IgA antibody comprises one, two, or three of CDR1, CDR2, or CDR3 of the light chain of antibody ch14.18. In some embodiments, the IgA antibody comprises one, two, or three of CDR1, CDR2, or CDR3 of the heavy chain of antibody ch14.18 and one, two, or three of CDR1, CDR2, or CDR3 of the light chain of antibody ch14.18. In some embodiments, the IgA antibody comprises CDR1, CDR2, or CDR3 of the heavy chain of antibody ch14.18 and CDR1, CDR2, or CDR3 of the light chain of antibody ch14.18. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of antibody ch14.18 and an IgA hinge. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of antibody ch14.18, an IgA hinge, a CH1 IgA region. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of antibody ch14.18, an IgA hinge, a CH1 IgA region, and a CH2 IgA region. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of antibody ch14.18, an IgA hinge, a CH1 IgA region, a CH2 IgA region, and a CH3 IgA region. In some embodiments, the IgA antibody comprises a heavy chain variable region comprising the amino acid sequence:In some embodiments, the IgA antibody comprises a heavy chain variable region comprising the amino acid sequence: EVQLLQSGPELEKPGASVMISCKASGSSFTGYNMNWVRQNIGKSLEWIGAIDPYYGGTSYNQKFKGRATLTVDKSSSTAYMHLKSLTSEDSAVYYCVSGMEYWGQGTSVTVSS [SEQ ID NO:4] and a light chain variable region comprising the amino acid sequence: EIVMTQSPATLSVSPGERATLSCRSSQSLVHRNGNTYLHWYLQKPGQSPKLLIHKVSNRFSGVPDRFSGSGSGTDFTLKISRVEAEDLGVYFCSQSTHVPPLTFGAGTKLELK [SEQ ID NO:5].

[0296] In some embodiments, the IgA antibody comprises a variable heavy chain comprising one or more of: a CDR1 comprising the amino acid sequence: EFTFTDYY [SEQ ID NO: 10]; a CDR2 comprising the amino acid sequence: IRNRANGYTT [SEQ ID NO: 11]; a CDR3 comprising the amino acid sequence: ARVSNWAFDY [SEQ ID NO: 12]. In some embodiments, the IgA antibody comprises a variable light chain comprising one or more of: a CDR1 comprising the amino acid sequence: QSLLKNNGNTFL [SEQ ID NO: 13]; a CDR2 comprising the amino acid sequence: KVS [SEQ ID NO: 14]; a CDR3 comprising the amino acid sequence: SQSTHIPYT [SEQ ID NO: 15].

[0297] In some embodiments, the IgA antibody comprises a variable heavy chain comprising one or more of: a CDR1 comprising the amino acid sequence: EFTFTDYY [SEQ ID NO: 10]; a CDR2 comprising the amino acid sequence: IRNRANGYTT [SEQ ID NO: 11]; a CDR3 comprising the amino acid sequence: ARVSNWAFDY [SEQ ID NO: 12]; and a variable light chain comprising one or more of: a CDR1 comprising the amino acid sequence: QSLLKNNGNTFL [SEQ ID NO: 13]; a CDR2 comprising the amino acid sequence: KVS [SEQ ID NO: 14]; a CDR3 comprising the amino acid sequence: SQSTHIPYT [SEQ ID NO: 15].

[0298] In some embodiments, the anti-GD2 IgA antibody comprises one or more (e.g., two, three, four, five, or six) of the HC-CDR1, HC-CDR2, HC-CDR3, LC-CDR1, LC-CDR2, LC- CDR3 of the 3F8 antibody. In some embodiments, the anti-GD2 antibody comprises the variable heavy chain and / or the variable light chain of the 3F8 antibody.

[0299] In one aspect, the present disclosure provides an antibody or antigen-binding fragment thereof, comprising one or more variable regions selected from the group consisting of: (a) a VH comprising the amino acid sequence of SEQ ID NO: 4, (b) a VL comprising the amino acid sequence of SEQ ID NO: 5, and (c) combinations thereof.

[0300] In one aspect, the present disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, two, three, four, five, or six CDRs selected from: (a) HC- CDR1 comprising the amino acid sequence of SEQ ID NO: 34; (b) HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 42; (c) HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 50; (d) LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 58; (e) LC-CDR2 comprising the amino acid sequence of SEQ ID NO: 66; and (f) LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 74.

[0301] In one aspect, the present disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VH CDR sequences selected from: (a) HC- CDR1 comprising the amino acid sequence of SEQ ID NO: 34; (b) HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 42; and (c) HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 50; and (d) a VL comprising the amino acid sequence of SEQ ID NO: 5.

[0302] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from the group consisting of: (a) an LC-CDR1 comprising an amino acid sequence of SEQ ID NO:58; (b) an LC-CDR2 comprising an amino acid sequence of SEQ ID NO:66; and (c) an LC-CDR3 comprising an amino acid sequence of SEQ ID NO:74; and a VH comprising an amino acid sequence of SEQ ID NO:4.

[0303] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising the following CDRs: an HC-CDR3 comprising an amino acid sequence of SEQ ID NO:50; and an LC-CDR3 comprising an amino acid sequence of SEQ ID NO:74.

[0304] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from the group consisting of: (a) an LC-CDR1 comprising an amino acid sequence of SEQ ID NO:58; (b) an LC-CDR2 comprising an amino acid sequence of SEQ ID NO:66; and (c) an LC-CDR3 comprising an amino acid sequence of SEQ ID NO:74. In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VH CDR sequences selected from the group consisting of: (a) an HC-CDR1 comprising an amino acid sequence of SEQ ID NO:34; (b) an HC-CDR2 comprising an amino acid sequence of SEQ ID NO:42; and (c) an HC-CDR3 comprising an amino acid sequence of SEQ ID NO:50.

[0305] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising the following CDRs: (a) an HC-CDR1 comprising an amino acid sequence of SEQ ID NO:34; (b) an HC-CDR2 comprising an amino acid sequence of SEQ ID NO:42; (c) an HC-CDR3 comprising an amino acid sequence of SEQ ID NO:50; (d) an LC-CDR1 comprising an amino acid sequence of SEQ ID NO:58; (e) an LC-CDR2 comprising an amino acid sequence of SEQ ID NO:66; and (f) an LC-CDR3 comprising an amino acid sequence of SEQ ID NO:74.

[0306] In one aspect, the antibody or antigen-binding fragment thereof comprises a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of SEQ ID NO: 4. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody or antigen-binding fragment thereof comprising that sequence retains the ability to bind to antigen. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of SEQ ID NO: 4. In some embodiments, substitutions, insertions, or deletions occur in regions outside the CDRs (e.g., in the FRs). Optionally, the antibody or antigen-binding fragment thereof comprises the VH sequence of the amino acid sequence of SEQ ID NO: 4, including post-translational modifications of that sequence. In particular embodiments, the VH comprises one, two, or three CDRs selected from (a) HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 34, (b) HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 42, and (c) HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 50.

[0307] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain variable domain (VH) having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of SEQ ID NO: 4. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody, or antigen-binding fragment thereof, comprising that sequence retains the ability to bind to antigen. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of SEQ ID NO: 4. In some embodiments, the substitutions, insertions, or deletions occur in regions outside the CDRs (e.g., in the FRs). Optionally, the antibody, or antigen-binding fragment thereof, comprises the VH sequence of SEQ ID NO: 4, including post-translational modifications of that sequence. In particular embodiments, the VH comprises one, two, or three CDRs selected from: (a) a HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 10; (b) a HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 18; and (c) a HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 26.

[0308] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a VH as in any of the embodiments provided above and a VL as in any of the embodiments provided above. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 4, and a VL sequence in SEQ ID NO: 5, including post-translational modifications of these sequences. In some embodiments, the antibody or antigen-binding fragment thereof comprises an IgA heavy chain constant region having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any of SEQ ID NOs: 16-21. In some embodiments, the antibody or antigen-binding fragment thereof comprises a kappa light chain constant region of SEQ ID NO: 31.

[0309] CD20

[0310] In some embodiments, the IgA antibody specifically binds CD20. In some embodiments, the IgA antibody comprises an antigen binding domain comprising a Type II or Type I / II CD20 binding region. In some embodiments, the antibody or functional fragment disclosed herein specifically binds to a human CD20 polypeptide. Polypeptides and encoding nucleic acid sequences of CD20 of human origin and of many animal origins are publicly available, e.g., available from the NCBI website. In some embodiments, the IgA antibody comprises an antigen binding domain that specifically binds to a CD20 epitope, wherein the CD20 epitope is within the following amino acid sequence: YNCEPANPSEKNSPSTQYCYS [SEQ ID NO: 6].

[0311] In some embodiments, the variable region of the CD20 antibody is described in PCT NL2017050581, which is incorporated by reference herein in its entirety. In some embodiments, the heavy chain variable region comprises one, two, or three of CDR1, CDR2, or CDR3 within the following amino acid sequence: QAYLQQSGAELVRPGASVKMSCKASGYTFTSYNLHWVKQTPRQGLEWIGAIYPGNGDTSYNQKFKGKATLTVDKSSSTAYMQLSRLTSEDSAVYFCARSNSYGSTYWYFDVWGTGTTVTVSS [SEQ ID NO: 7]. In some embodiments, the light chain variable region comprises one, two, or three of CDR1, CDR2, or CDR3 within the following amino acid sequence: QIVLSQSPAVLFASPGEKVTMTCRARSSVSYMDWYQQKPRSSPKPWIYATSNLASGVPARFSGSGSGTSYSLTISRVEAEDAATYYCQQWTSNPPTFGSGTKLEIKRADAAPTVSIFPPSS [SEQ ID NO: 8].

[0312] In some embodiments, the heavy chain variable region comprises the following amino acid sequence: QAYLQQSGAELVRPGASVKMSCKASGYTFTSYNLHWVKQTPRQGLEWIGAIYPGNGDTSYNQKFKGKATLTVDKSSSTAYMQLSRLTSEDSAVYFCARSNSYGSTYWYFDVWGTGTTVTVSS [SEQ ID NO: 7]. In some embodiments, the light chain variable region comprises the following amino acid sequence: QIVLSQSPAVLFASPGEKVTMTCRARSSVSYMDWYQQKPRSSPKPWIYATSNLASGVPARFSGSGSGTSYSLTISRVEAEDAATYYCQQWTSNPPTFGSGTKLEIKRADAAPTVSIFPPSS [SEQ ID NO: 8].

[0313] In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of the antibody obinutuzumab. In some embodiments, the IgA antibody comprises one, two, or three of the CDR1, CDR2, or CDR3 of the heavy chain of the antibody obinutuzumab. In some embodiments, the IgA antibody comprises one, two, or three of the CDR1, CDR2, or CDR3 of the light chain of the antibody obinutuzumab. In some embodiments, the IgA antibody comprises one, two, or three of the CDR1, CDR2, or CDR3 of the heavy chain of the antibody obinutuzumab and one, two, or three of the CDR1, CDR2, or CDR3 of the light chain of the antibody obinutuzumab. In some embodiments, the IgA antibody comprises the CDR1, CDR2, or CDR3 of the heavy chain of the antibody obinutuzumab and the CDR1, CDR2, or CDR3 of the light chain of the antibody obinutuzumab. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of the antibody obinutuzumab and an IgA hinge. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of the antibody obinutuzumab, an IgA hinge, a CH1 IgA region. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of the antibody obinutuzumab, an IgA hinge, a CH1 IgA region, and a CH2 IgA region. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of the antibody obinutuzumab, an IgA hinge, a CH1 IgA region, a CH2 IgA region, and a CH3 IgA region.

[0314] In some embodiments, the IgA antibody specifically binds to the CD20 epitope EPANPSEK.

[0315] In some embodiments, the IgA antibody specifically binds CD20 and has increased programmed cell death (PCD) function compared to rituximab having the same isotype constant region. In some embodiments, the IgA antibody specifically binds CD20 and has increased antibody-dependent cell-mediated cytotoxicity (ADCC) function compared to rituximab having the same isotype constant region. In some embodiments, the IgA antibody specifically binds CD20 and has increased complement-dependent cytotoxicity (CDC) function compared to rituximab having the same isotype constant region.

[0316] In some embodiments, the IgA antibody has a shorter circulating half-life compared to a corresponding IgG antibody. In some embodiments, administration of the anti-CD20 IgA antibody is associated with fewer side effects from B cell depletion compared to a corresponding IgG antibody. In some embodiments, administration of the anti-CD20 antibody is associated with faster B cell replenishment compared to a corresponding IgG antibody.

[0317] In one aspect, the present disclosure provides an antibody or antigen-binding fragment thereof, comprising one or more variable regions selected from the group consisting of: (a) a VH comprising an amino acid sequence of SEQ ID NO: 81, (b) a VL comprising an amino acid sequence of SEQ ID NO: 95, and (c) a combination thereof.

[0318] In one aspect, the present disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, two, three, four, five, or six CDRs selected from: (a) HC- CDR1 comprising an amino acid sequence of SEQ ID NO: 33; (b) HC-CDR2 comprising an amino acid sequence of SEQ ID NO: 41; (c) HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 49; (d) LC-CDR1 comprising an amino acid sequence of SEQ ID NO: 57; (e) LC-CDR2 comprising an amino acid sequence of SEQ ID NO: 65; and (f) LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 73.

[0319] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from the group consisting of: (a) LC-CDR1 comprising an amino acid sequence of SEQ ID NO: 57; (b) LC-CDR2 comprising an amino acid sequence of SEQ ID NO: 65; and (c) LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 73; and a VH comprising an amino acid sequence of SEQ ID NO: 81.

[0320] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from the group consisting of: (a) LC-CDR1 comprising an amino acid sequence of SEQ ID NO: 57; (b) LC-CDR2 comprising an amino acid sequence of SEQ ID NO: 65; and (c) LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 73; and a VH comprising an amino acid sequence of SEQ ID NO: 81.

[0321] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising the following CDRs: HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 49; and LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 73.

[0322] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from the group consisting of: (a) LC-CDR1 comprising an amino acid sequence of SEQ ID NO: 57; (b) LC-CDR2 comprising an amino acid sequence of SEQ ID NO: 65; and (c) LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 73. In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VH CDR sequences selected from the group consisting of: (a) HC-CDR1 comprising an amino acid sequence of SEQ ID NO: 33; (b) HC-CDR2 comprising an amino acid sequence of SEQ ID NO: 41; and (c) HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 49.

[0323] In one aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising the following CDRs: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 33; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 41; (c) an HC- CDR3 comprising the amino acid sequence of SEQ ID NO: 49; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 57; (e) an LC-CDR2 comprising the amino acid sequence of SEQ ID NO: 65; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 73.

[0324] In one aspect, the antibody or antigen-binding fragment thereof comprises a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of SEQ ID NO: 81. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody, or antigen-binding fragment thereof, comprising that sequence retains the ability to bind to antigen. In some embodiments, a total of from 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of SEQ ID NO: 81. In some embodiments, substitutions, insertions, or deletions occur in regions outside the CDRs (e.g., in the FRs). Optionally, the antibody or antigen-binding fragment thereof comprises a VH sequence of the amino acid sequence of SEQ ID NO: 81, including post-translational modifications of that sequence. In particular embodiments, the VH comprises one, two, or three CDRs selected from (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 33; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 41; and (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 49.

[0325] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain variable domain (VH) having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 1-6. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody, or antigen-binding fragment thereof, comprising that sequence retains the ability to bind to an antigen. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of any one of SEQ ID NOs: 1-6. In some embodiments, the substitutions, insertions, or deletions occur in regions outside of the CDRs (e.g., in the FRs). Optionally, the antibody or antigen-binding fragment thereof comprises a VH sequence of any one of SEQ ID NOs: 1-6, including post-translational modifications of these sequences. In some embodiments, the VH comprises one, two, or three CDRs selected from: (a) a HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 7; (b) a HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 8; and (c) a HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 9.

[0326] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a VH as in any of the embodiments provided above and a VL as in any of the embodiments provided above. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 81, and a VL sequence in SEQ ID NO: 95, including post-translational modifications of these sequences. In some embodiments, the antibody or antigen-binding fragment thereof comprises an IgA heavy chain constant region having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 16-21. In some embodiments, the antibody or antigen-binding fragment thereof comprises a kappa light chain constant region of SEQ ID NO: 31.

[0327] In some embodiments, provided herein are antibodies or functional fragments thereof that specifically bind CD20. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of antibody UMAB10. In some embodiments, the IgA antibody comprises one, two, or three of CDR1, CDR2, or CDR3 of the heavy chain of antibody UMAB10. In some embodiments, the IgA antibody comprises one, two, or three of CDR1, CDR2, or CDR3 of the light chain of antibody UMAB10. In some embodiments, the IgA antibody comprises one, two, or three of CDR1, CDR2, or CDR3 of the heavy chain of antibody UMAB10 and one, two, or three of CDR1, CDR2, or CDR3 of the light chain of antibody UMAB10. In some embodiments, the IgA antibody comprises CDR1, CDR2, or CDR3 of the heavy chain of antibody UMAB10 and CDR1, CDR2, or CDR3 of the light chain of antibody UMAB10. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of antibody UMAB10 and an IgA hinge. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of antibody UMAB10, an IgA hinge, a CH1 IgA region. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of antibody UMAB10, an IgA hinge, a CH1 IgA region, and a CH2 IgA region. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of antibody UMAB10, an IgA hinge, a CH1 IgA region, a CH2 IgA region, and a CH3 IgA region.

[0328] In one aspect, the present disclosure provides an antibody or antigen binding fragment thereof, comprising one or more variable regions selected from the group consisting of: (a) a VH comprising an amino acid sequence of SEQ ID NO: 86, (b) a VL comprising an amino acid sequence of SEQ ID NO: 100, and (c) a combination thereof.

[0329] In one aspect, the present disclosure provides an antibody or antigen binding fragment thereof, comprising at least one, two, three, four, five, or six CDRs selected from: (a) HC- CDR1 comprising an amino acid sequence of SEQ ID NO: 40; (b) HC-CDR2 comprising an amino acid sequence of SEQ ID NO: 48; (c) HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 56; (d) LC-CDR1 comprising an amino acid sequence of SEQ ID NO: 64; (e) LC-CDR2 comprising an amino acid sequence of SEQ ID NO: 72; and (f) LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 80.

[0330] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from the group consisting of: (a) LC-CDR1 comprising an amino acid sequence of SEQ ID NO:64; (b) LC-CDR2 comprising an amino acid sequence of SEQ ID NO:72; and (c) LC-CDR3 comprising an amino acid sequence of SEQ ID NO:80; and a VH comprising an amino acid sequence of SEQ ID NO:7.

[0331] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from the group consisting of: (a) LC-CDR1 comprising an amino acid sequence of SEQ ID NO:64; (b) LC-CDR2 comprising an amino acid sequence of SEQ ID NO:72; and (c) LC-CDR3 comprising an amino acid sequence of SEQ ID NO:80; and a VH comprising an amino acid sequence of SEQ ID NO:7.

[0332] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising the following CDRs: HC-CDR3 comprising an amino acid sequence of SEQ ID NO:56; and LC-CDR3 comprising an amino acid sequence of SEQ ID NO:80.

[0333] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from the group consisting of: (a) LC-CDR1 comprising an amino acid sequence of SEQ ID NO:64; (b) LC-CDR2 comprising an amino acid sequence of SEQ ID NO:72; and (c) LC-CDR3 comprising an amino acid sequence of SEQ ID NO:80. In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VH CDR sequences selected from the group consisting of: (a) HC-CDR1 comprising an amino acid sequence of SEQ ID NO:40; (b) HC-CDR2 comprising an amino acid sequence of SEQ ID NO:48; and (c) HC-CDR3 comprising an amino acid sequence of SEQ ID NO:56.

[0334] In one aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising the following CDRs: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 40; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 48; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 56; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 64; (e) an LC-CDR2 comprising the amino acid sequence of SEQ ID NO: 72; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 80.

[0335] In one aspect, the antibody or antigen-binding fragment thereof comprises a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of SEQ ID NO: 7. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody, or antigen-binding fragment thereof, comprising that sequence retains the ability to bind to antigen. In some embodiments, a total of from 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of SEQ ID NO: 7. In some embodiments, substitutions, insertions, or deletions occur in regions outside the CDRs (e.g., in the FRs). Optionally, the antibody or antigen-binding fragment thereof comprises a VH sequence of the amino acid sequence of SEQ ID NO: 7, including post-translational modifications of that sequence. In particular embodiments, the VH comprises one, two, or three CDRs selected from (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 40, (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 48, and (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 56.

[0336] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain variable domain (VH) having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of SEQ ID NO: 7. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody, or antigen-binding fragment thereof, comprising that sequence retains the ability to bind to antigen. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of SEQ ID NO: 7. In some embodiments, the substitutions, insertions, or deletions occur in regions outside the CDRs (e.g., in the FRs). Optionally, the antibody, or antigen-binding fragment thereof, comprises the VH sequence of SEQ ID NO: 7, including post-translational modifications of that sequence. In particular embodiments, the VH comprises one, two, or three CDRs selected from: (a) a HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 62; (b) a HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 70; and (c) a HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 78.

[0337] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a VH as in any of the embodiments provided above and a VL as in any of the embodiments provided above. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL sequence in SEQ ID NO: 8, including post-translational modifications of these sequences. In some embodiments, the antibody or antigen-binding fragment thereof comprises an IgA heavy chain constant region having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any of SEQ ID NOs: 16-21. In some embodiments, the antibody or antigen-binding fragment thereof comprises a kappa light chain constant region of SEQ ID NO: 31.

[0338] Her2

[0339] In some embodiments, provided herein are antibodies or functional fragments thereof that specifically bind Her2. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of the antibody trastuzumab. In some embodiments, the IgA antibody comprises one, two, or three of CDR1, CDR2, or CDR3 of the heavy chain of the antibody trastuzumab. In some embodiments, the IgA antibody comprises one, two, or three of CDR1, CDR2, or CDR3 of the light chain of the antibody trastuzumab. In some embodiments, the IgA antibody comprises one, two, or three of CDR1, CDR2, or CDR3 of the heavy chain of the antibody trastuzumab and one, two, or three of CDR1, CDR2, or CDR3 of the light chain of the antibody trastuzumab. In some embodiments, the IgA antibody comprises CDR1, CDR2, or CDR3 of the heavy chain of the antibody trastuzumab and CDR1, CDR2, or CDR3 of the light chain of the antibody trastuzumab. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of the antibody trastuzumab and an IgA hinge. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of the antibody trastuzumab, an IgA hinge, a CH1 IgA region. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of the antibody trastuzumab, an IgA hinge, a CH1 IgA region, and a CH2 IgA region. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of the antibody trastuzumab, an IgA hinge, a CH1 IgA region, a CH2 IgA region, and a CH3 IgA region.

[0340] In one aspect, the present disclosure provides an antibody or antigen binding fragment thereof, comprising one or more variable regions selected from the group consisting of: (a) a VH comprising an amino acid sequence of SEQ ID NO: 82, (b) a VL comprising an amino acid sequence of SEQ ID NO: 96, and (c) a combination thereof.

[0341] In one aspect, the present disclosure provides an antibody or antigen binding fragment thereof, comprising at least one, two, three, four, five, or six CDRs selected from: (a) HC- CDR1 comprising an amino acid sequence of SEQ ID NO: 35; (b) HC-CDR2 comprising an amino acid sequence of SEQ ID NO: 43; (c) HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 51; (d) LC-CDR1 comprising an amino acid sequence of SEQ ID NO: 59; (e) LC- CDR2 comprising an amino acid sequence of SEQ ID NO: 67; and (f) LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 75.

[0342] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from the group consisting of: (a) LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 59; (b) LC-CDR2 comprising the amino acid sequence of SEQ ID NO: 67; and (c) LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 75; and a VH comprising the amino acid sequence of SEQ ID NO: 82.

[0343] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from the group consisting of: (a) LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 59; (b) LC-CDR2 comprising the amino acid sequence of SEQ ID NO: 67; and (c) LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 75; and a VH comprising the amino acid sequence of SEQ ID NO: 82.

[0344] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising the following CDRs: HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 51; and LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 75.

[0345] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from the group consisting of: (a) LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 59; (b) LC-CDR2 comprising the amino acid sequence of SEQ ID NO: 67; and (c) LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 75. In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VH CDR sequences selected from the group consisting of: (a) HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 35; (b) HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 43; and (c) HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 51.

[0346] In one aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising the following CDRs: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 35; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 43; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 51; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 59; (e) an LC-CDR2 comprising the amino acid sequence of SEQ ID NO: 67; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 75.

[0347] In one aspect, the antibody or antigen-binding fragment thereof comprises a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of SEQ ID NO: 82. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody, or antigen-binding fragment thereof, comprising that sequence retains the ability to bind to antigen. In some embodiments, a total of from 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of SEQ ID NO: 82. In some embodiments, substitutions, insertions, or deletions occur in regions outside the CDRs (e.g., in the FRs). Optionally, the antibody or antigen-binding fragment thereof comprises a VH sequence of the amino acid sequence of SEQ ID NO: 82, including post-translational modifications of that sequence. In particular embodiments, the VH comprises one, two, or three CDRs selected from (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 35, (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 43, and (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 51.

[0348] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain variable domain (VH) having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 1-6. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody, or antigen-binding fragment thereof, comprising that sequence retains the ability to bind to an antigen. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of any one of SEQ ID NOs: 1-6. In some embodiments, the substitutions, insertions, or deletions occur in regions outside of the CDRs (e.g., in the FRs). Optionally, the antibody, or antigen-binding fragment thereof, comprises the VH sequence of any one of SEQ ID NOs: 1-6, including post-translational modifications of that sequence. In some embodiments, the VH comprises one, two, or three CDRs selected from: (a) a HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 7; (b) a HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 15; and (c) a HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 23.

[0349] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a VH as in any of the embodiments provided above and a VL as in any of the embodiments provided above. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 82, and a VL sequence in SEQ ID NO: 96, including post-translational modifications of those sequences. In some embodiments, the antibody or antigen-binding fragment thereof comprises an IgA heavy chain constant region having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 16-21. In some embodiments, the antibody or antigen-binding fragment thereof comprises a kappa light chain constant region of SEQ ID NO: 31.

[0350] gp75

[0351] In some embodiments, provided herein are antibodies or functional fragments thereof that specifically bind gp75 or tyrosinase-related protein 1. In some embodiments, the antibodies or functional fragments disclosed herein specifically bind a human gp75 polypeptide. Polypeptides and encoding nucleic acid sequences of gp75 of human origin and of many animal origins are publicly available, e.g., available from the NCBI website. In some embodiments, the IgA antibody comprises at least CDR3 of the heavy chain of antibody TA99. In some embodiments, the IgA antibody comprises one, two, or three of CDR1, CDR2, or CDR3 of the heavy chain of antibody TA99. In some embodiments, the IgA antibody comprises one, two, or three of CDR1, CDR2, or CDR3 of the light chain of antibody TA99. In some embodiments, the IgA antibody comprises one, two, or three of CDR1, CDR2, or CDR3 of the heavy chain of antibody TA99, and one, two, or three of CDR1, CDR2, or CDR3 of the light chain of antibody TA99. In some embodiments, the IgA antibody comprises CDR1, CDR2, or CDR3 of the heavy chain of antibody TA99, and CDR1, CDR2, or CDR3 of the light chain of antibody TA99. In some embodiments, the IgA antibody comprises at least CDR3 of the heavy chain of antibody TA99 and an IgA hinge. In some embodiments, the IgA antibody comprises at least CDR3 of the heavy chain of antibody TA99, an IgA hinge, a CH1 IgA region. In some embodiments, the IgA antibody comprises at least CDR3 of the heavy chain of antibody TA99, an IgA hinge, a CH1 IgA region, and a CH2 IgA region. In some embodiments, the IgA antibody comprises at least CDR3 of the heavy chain of antibody TA99, an IgA hinge, a CH1 IgA region, a CH2 IgA region, and a CH3 IgA region.

[0352] In one aspect, the present disclosure provides an antibody or antigen-binding fragment thereof, comprising one or more variable regions selected from the group consisting of: (a) a VH comprising the amino acid sequence of SEQ ID NO: 83, (b) a VL comprising the amino acid sequence of SEQ ID NO: 97, and (c) combinations thereof.

[0353] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, two, three, four, five, or six CDRs selected from: (a) HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 36; (b) HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 44; (c) HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 52; (d) LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 60; (e) LC-CDR2 comprising the amino acid sequence of SEQ ID NO: 68; and (f) LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 76.

[0354] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VH CDR sequences selected from: (a) HC- CDR1 comprising the amino acid sequence of SEQ ID NO: 36; (b) HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 44; and (c) HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 52; and (d) VL comprising the amino acid sequence of SEQ ID NO: 97.

[0355] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from: (a) LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 60; (b) LC-CDR2 comprising the amino acid sequence of SEQ ID NO: 68; and (c) LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 76; and VH comprising the amino acid sequence of SEQ ID NO: 83.

[0356] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising the following CDRs: HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 52; and LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 76.

[0357] In one aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from: (a) LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 60; (b) LC-CDR2 comprising the amino acid sequence of SEQ ID NO: 68; and (c) LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 76. In one aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VH CDR sequences selected from: (a) HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 36; (b) HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 44; and (c) HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 52.

[0358] In one aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising the following CDRs: (a) HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 36, (b) HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 44; (c) HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 52; (d) LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 60; (e) LC-CDR2 comprising the amino acid sequence of SEQ ID NO: 68; and (f) LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 76.

[0359] In one aspect, the antibody or antigen-binding fragment thereof comprises a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of SEQ ID NO: 83. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody or antigen-binding fragment thereof comprising that sequence retains the ability to bind to antigen. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of SEQ ID NO: 83. In some embodiments, substitutions, insertions, or deletions occur in regions outside the CDRs (e.g., in the FRs). Optionally, the antibody or antigen-binding fragment thereof comprises the VH sequence of the amino acid sequence of SEQ ID NO: 83, including post-translational modifications of that sequence. In particular embodiments, the VH comprises one, two, or three CDRs selected from (a) HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 36, (b) HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 44, and (c) HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 52.

[0360] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain variable domain (VH) having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 1-8. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody, or antigen-binding fragment thereof, comprising that sequence retains the ability to bind to an antigen. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of any one of SEQ ID NOs: 1-8. In some embodiments, the substitutions, insertions, or deletions occur in regions outside of the CDRs (e.g., in the FRs). Optionally, the antibody or antigen-binding fragment thereof comprises a VH sequence of any one of SEQ ID NOs: 1-8, including post-translational modifications of that sequence. In some embodiments, the VH comprises one, two, or three CDRs selected from: (a) a HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 9; (b) a HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 17; and (c) a HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 25.

[0361] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a VH as in any of the embodiments provided above and a VL as in any of the embodiments provided above. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 83, and a VL sequence in SEQ ID NO: 97, including post-translational modifications of those sequences. In some embodiments, the antibody or antigen-binding fragment thereof comprises an IgA heavy chain constant region having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 16-21. In some embodiments, the antibody or antigen-binding fragment thereof comprises a kappa light chain constant region of SEQ ID NO: 31.

[0362] CTLA4

[0363] In some embodiments, provided herein are antibodies or functional fragments thereof that specifically bind cytotoxic T-lymphocyte-associated protein 4 (CTLA4). In some embodiments, the antibodies or functional fragments disclosed herein specifically bind a human CTLA4 polypeptide. In some embodiments, the antibodies or functional fragments disclosed herein specifically bind a mouse CTLA4 polypeptide. Polypeptides and encoding nucleic acid sequences of CTLA4 of human origin and of many animal origins are publicly available, e.g., available from the NCBI website.

[0364] In one aspect, the present disclosure provides an antibody or antigen binding fragment thereof, comprising one or more variable regions selected from the group consisting of: (a) a VH comprising an amino acid sequence of SEQ ID NO: 84, (b) a VL comprising an amino acid sequence of SEQ ID NO: 98, and (c) a combination thereof.

[0365] In one aspect, the present disclosure provides an antibody or antigen binding fragment thereof, comprising at least one, two, three, four, five, or six CDRs selected from: (a) HC-CDR1 comprising an amino acid sequence of SEQ ID NO: 37; (b) HC-CDR2 comprising an amino acid sequence of SEQ ID NO: 45; (c) HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 53; (d) LC-CDR1 comprising an amino acid sequence of SEQ ID NO: 61; (e) LC-CDR2 comprising an amino acid sequence of SEQ ID NO: 69; and (f) LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 77.

[0366] In one aspect, the present disclosure provides an antibody or antigen binding fragment thereof, comprising at least one, at least two, or all three VH CDR sequences selected from: (a) HC- CDR1 comprising an amino acid sequence of SEQ ID NO: 37; (b) HC-CDR2 comprising an amino acid sequence of SEQ ID NO: 45; and (c) HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 53; and (d) a VL comprising an amino acid sequence of SEQ ID NO: 98.

[0367] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from the group consisting of: (a) LC-CDR1 comprising an amino acid sequence of SEQ ID NO: 61; (b) LC-CDR2 comprising an amino acid sequence of SEQ ID NO: 69; and (c) LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 77; and a VH comprising an amino acid sequence of SEQ ID NO: 84.

[0368] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising the following CDRs: HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 53; and LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 77.

[0369] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from the group consisting of: (a) LC-CDR1 comprising an amino acid sequence of SEQ ID NO: 61; (b) LC-CDR2 comprising an amino acid sequence of SEQ ID NO: 69; and (c) LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 77. In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VH CDR sequences selected from the group consisting of: (a) HC-CDR1 comprising an amino acid sequence of SEQ ID NO: 37; (b) HC-CDR2 comprising an amino acid sequence of SEQ ID NO: 45; and (c) HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 53.

[0370] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising the following CDRs: (a) HC-CDR1 comprising an amino acid sequence of SEQ ID NO: 37, (b) HC-CDR2 comprising an amino acid sequence of SEQ ID NO: 45; (c) HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 53; (d) LC-CDR1 comprising an amino acid sequence of SEQ ID NO: 61; (e) LC-CDR2 comprising an amino acid sequence of SEQ ID NO: 69; and (f) LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 77.

[0371] In one aspect, the antibody or antigen-binding fragment thereof comprises a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of SEQ ID NO: 84. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody or antigen-binding fragment thereof comprising that sequence retains the ability to bind to antigen. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of SEQ ID NO: 84. In some embodiments, substitutions, insertions, or deletions occur in regions outside the CDRs (e.g., in the FRs). Optionally, the antibody or antigen-binding fragment thereof comprises the VH sequence of the amino acid sequence of SEQ ID NO: 84, including post-translational modifications of that sequence. In particular embodiments, the VH comprises one, two, or three CDRs selected from (a) HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 37, (b) HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 45, and (c) HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 53.

[0372] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain variable domain (VH) having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 1-6. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody, or antigen-binding fragment thereof, comprising that sequence retains the ability to bind to an antigen. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of any one of SEQ ID NOs: 1-6. In some embodiments, the substitutions, insertions, or deletions occur in regions outside of the CDRs (e.g., in the FRs). Optionally, the antibody, or antigen-binding fragment thereof, comprises the VH sequence of any one of SEQ ID NOs: 1-6, including post-translational modifications of that sequence. In some embodiments, the VH comprises one, two, or three CDRs selected from: (a) a HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 7; (b) a HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 15; and (c) a HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 23.

[0373] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a VH as in any of the embodiments provided above and a VL as in any of the embodiments provided above. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 84, and a VL sequence in SEQ ID NO: 98, including post-translational modifications of those sequences. In some embodiments, the antibody or antigen-binding fragment thereof comprises an IgA heavy chain constant region having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 16-21. In some embodiments, the antibody or antigen-binding fragment thereof comprises a kappa light chain constant region of SEQ ID NO: 31.

[0374] CD47

[0375] In some embodiments, the IgA antibody specifically binds CD47. In some embodiments, the antibody or functional fragment disclosed herein specifically binds a human CD47 polypeptide. Polypeptides and encoding nucleic acid sequences of CD47 of human origin and of many animal origins are publicly available, e.g., available from the NCBI website. In some embodiments, the IgA antibody reduces the binding of SIRPa to CD47 expressed on the surface of a cancer cell. In some embodiments, the IgA antibody binds to CD47 with a binding affinity (Kd) ranging from about 0.5 mM to about 999 mM as compared to a corresponding wild-type antibody. In some embodiments, the IgA antibody binds to CD47 with a binding affinity (Kd) ranging from about 1 mM to about 1000 mM as compared to a corresponding wild-type antibody. In some embodiments, the IgA antibody inhibits the interaction of human CD47 with signal regulatory protein alpha (SIRPa). In some embodiments, inhibiting the interaction between the human CD47 and the SIRPa increases the potential of the IgA antibody. In some embodiments, inhibiting the interaction between the human CD47 and the SIRPa increases phagocytosis and clearance of cancer cells at a tumor site. In some embodiments, the cancer cell is an IgA opsonized cancer cell. In some embodiments, the IgA antibody comprises an antigen binding domain that binds CD47 and an antigen binding domain that specifically binds a tumor associated antigen (e.g., an antigen binding domain described herein).

[0376] In some embodiments, the IgA antibody binds to CD47. In some embodiments, the IgA antibody reduces the binding of CD47 to cancer cells. For example, the IgA antibody can inhibit the interaction of human CD47 with signal regulatory protein alpha (SIRPa). Further, inhibiting the interaction between human CD47 and SIRPa can increase the potency of the IgA antibody. Inhibiting the interaction between human CD47 and SIRPa can increase phagocytosis and clearance of cancer cells at the tumor site. For example, the cancer cells can be IgA-opsonized cancer cells. In some embodiments, the IgA antibodies described herein have low affinity binding to CD47, which prevents the IgA antibodies from binding to CD47 on cells other than cancer cells. In some embodiments, the low affinity CD47 arm of the IgA antibodies described herein binds to tumor cells expressing CD47. In some examples, the low affinity CD47 arm of the IgA antibodies described herein does not bind to non-tumor cells expressing CD47. In some embodiments, the IgA antibody binds to CD47 with a binding affinity (Kd) of at least about 0.01 micromolar per liter (pM) to about 999 pM or greater. In some embodiments, the IgA antibody binds to CD47 with a binding affinity (Kd) of at least about 0.01 pM. In some embodiments, the IgA antibody binds to CD47 with a binding affinity (Kd) of at most about 999 pM.In some embodiments, the IgA antibody binds to CD47 with a binding affinity (Kd) of about 0.01 pM to about 0.1 pM, about 0.01 pM to about 0.5 pM, about 0.01 pM to about 1 pM, about 0.01 pM to about 5 pM, about 0.01 pM to about 10 pM, about 0.01 pM to about 50 pM, about 0.01 pM to about 100 pM, about 0.01 pM to about 200 pM, about 0.01 pM to about 300 pM, about 0.01 pM to about 500 pM, about 0.01 pM to about 999 pM, about 0.1 pM to about 0.5 pM, about 0.1 pM to about 1 pM, about 0.1 pM to about 5 pM, about 0.1 pM to about 10 pM, about 0.1 pM to about 50 pM, about 0.1 pM to about 100 pM, about 0.1 pM to about 200 pM, about 0.1 pM to about 300 pM, about 0.1 pM to about 500 pM, about 0.1 pM to about 999 pM, about 0.5 pM to about 1 pM, about 0.5 pM to about 5 pM, about 0.5 pM to about 10 pM, about 0.5 pM to about 50 pM, about 0.5 pM to about 100 pM, about 0.5 pM to about 200 pM, about 0.5 pM to about 300 pM, about 0.5 pM to about 500 pM, about 0.5 pM to about 999 pM, about 1 pM to about 5 pM, about 1 pM to about 10 pM, about 1 pM to about 50 pM, about 1 pM to about 100 pM, about 1 pM to about 200 pM, about 1 pM to about 300 pM, about 1 pM to about 500 pM, about 1 pM to about 999 pM, about 5 pM to about 10 pM, about 5 pM to about 50 pM, about 5 pM to about 100 pM, about 5 pM to about 200 pM, about 5 pM to about 300 pM, about 5 pM to about 500 pM, about 5 pM to about 999 pM, about 10 pM to about 50 pM, about 10 pM to about 100 pM, about 10 pM to about 200 pM, about 10 pM to about 300 pM, about 10 pM to about 500 pM, about 10 pM to about 999 pM, about 50 pM to about 100 pM, about 50 pM to about 200 pM, about 50 pM to about 300 pM, about 50 pM to about 500 pM, about 50 pM to about 999 pM, about 100 pM to about 200 pM, about 100 pM to about 300 pM, about 100 pM to about 500 pM, about 100 pM to about 999 pM, about 200 pM to about 300 pM, about 200 pM to about 500 pM, about 200 pM to about 999 pM, about 300 pM to about 500 pM, about 300 pM to about 999 pM, or about 500 pM to about 999 pM.In some embodiments, the IgA antibody binds to CD47 with a binding affinity (Kd) of about 0.01 μΜ, about 0.1 μΜ, about 0.5 μΜ, about 1 μΜ, about 5 μΜ, about 10 μΜ, about 50 μΜ, about 100 μΜ, about 200 μΜ, about 300 μΜ, about 500 μΜ, or about 999 μΜ.

[0377] In some embodiments, the IgA antibody binds to CD47 with a binding affinity (Kd) of about 1 mM to about 1,000 millimolar (mM). In some embodiments, the IgA antibody binds to CD47 with a binding affinity (Kd) of at least about 1 mM. In some embodiments, the IgA antibody binds to CD47 with a binding affinity (Kd) of at most about 1,000 mM.In some embodiments, the IgA antibody binds to CD47 with a binding affinity (Kd) of about 1 mM to about 5 mM, about 1 mM to about 10 mM, about 1 mM to about 50 mM, about 1 mM to about 100 mM, about 1 mM to about 200 mM, about 1 mM to about 300 mM, about 1 mM to about 400 mM, about 1 mM to about 500 mM, about 1 mM to about 600 mM, about 1 mM to about 800 mM, about 1 mM to about 1,000 mM, about 5 mM to about 10 mM, about 5 mM to about 50 mM, about 5 mM to about 100 mM, about 5 mM to about 200 mM, about 5 mM to about 300 mM, about 5 mM to about 400 mM, about 5 mM to about 500 mM, about 5 mM to about 600 mM, about 5 mM to about 800 mM, about 5 mM to about 1,000 mM, about 10 mM to about 50 mM, about 10 mM to about 100 mM, about 10 mM to about 200 mM, about 10 mM to about 300 mM, about 10 mM to about 400 mM, about 10 mM to about 500 mM, about 10 mM to about 600 mM, about 10 mM to about 800 mM, about 10 mM to about 1,000 mM, about 50 mM to about 100 mM, about 50 mM to about 200 mM, about 50 mM to about 300 mM, about 50 mM to about 400 mM, about 50 mM to about 500 mM, about 50 mM to about 600 mM, about 50 mM to about 800 mM, about 50 mM to about 1,000 mM, about 100 mM to about 200 mM, about 100 mM to about 300 mM, about 100 mM to about 400 mM, about 100 mM to about 500 mM, about 100 mM to about 600 mM, about 100 mM to about 800 mM, about 100 mM to about 1,000 mM, about 200 mM to about 300 mM, about 200 mM to about 400 mM, about 200 mM to about 500 mM, about 200 mM to about 600 mM, about 200 mM to about 800 mM, about 200 mM to about 1,000 mM, about 300 mM to about 400 mM, about 300 mM to about 500 mM, about 300 mM to about 600 mM, about 300 mM to about 800 mM, about 300 mM to about 1,000 mM, about 400 mM to about 500 mM, about 400 mM to about 600 mM, about 400 mM to about 800 mM, about 400 mM to about 1,000 mM, about 500 mM to about 600 mM, about 500 mM to about 800 mM, about 500 mM to about 1,000 mM, about 600 mM to about 800 mM, about 600 mM to about 1,000 mM, or about 800 mM to about 1,000 mM.In some embodiments, the IgA antibody binds to CD47 with a binding affinity (Kd) of about 1 mM, about 5 mM, about 10 mM, about 50 mM, about 100 mM, about 200 mM, about 300 mM, about 400 mM, about 500 mM, about 600 mM, about 800 mM, or about 1,000 mM.

[0378] In some embodiments, provided herein are antibodies or functional fragments thereof that specifically bind CD47. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of antibody 2.3D11 or antibody C47A8-CQ. In some embodiments, the IgA antibody comprises one, two, or three of CDR1, CDR2, or CDR3 of the heavy chain of antibody 2.3D11 or antibody C47A8-CQ. In some embodiments, the IgA antibody comprises one, two, or three of CDR1, CDR2, or CDR3 of the light chain of antibody 2.3D11 or antibody C47A8-CQ. In some embodiments, the IgA antibody comprises one, two, or three of CDR1, CDR2, or CDR3 of the heavy chain of antibody 2.3D11 or antibody C47A8-CQ, and one, two, or three of CDR1, CDR2, or CDR3 of the light chain of antibody 2.3D11 or antibody C47A8-CQ. In some embodiments, the IgA antibody comprises CDR1, CDR2, or CDR3 of the heavy chain of antibody 2.3D11 or antibody C47A8-CQ, and CDR1, CDR2, or CDR3 of the light chain of antibody 2.3D11 or antibody C47A8-CQ. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of antibody 2.3D11 or antibody C47A8-CQ and an IgA hinge. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of antibody 2.3D11 or antibody C47A8-CQ, an IgA hinge, a CH1 IgA region. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of antibody 2.3D11 or antibody C47A8-CQ, an IgA hinge, a CH1 IgA region, and a CH2 IgA region. In some embodiments, the IgA antibody comprises at least the CDR3 of the heavy chain of antibody 2.3D11 or antibody C47A8-CQ, an IgA hinge, a CH1 IgA region, a CH2 IgA region, and a CH3 IgA region.

[0379] In one aspect, the present disclosure provides an antibody or antigen binding fragment thereof, comprising one or more variable regions selected from the group consisting of: (a) a VH comprising the amino acid sequence of SEQ ID NO: 85, (b) a VL comprising the amino acid sequence of SEQ ID NO: 99, and (c) a combination thereof.

[0380] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, two, three, four, five, or six CDRs selected from: (a) HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 38; (b) HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 46; (c) HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 54; (d) LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 62; (e) LC-CDR2 comprising the amino acid sequence of SEQ ID NO: 70; and (f) LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 78.

[0381] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VH CDR sequences selected from: (a) HC- CDR1 comprising the amino acid sequence of SEQ ID NO: 38; (b) HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 46; and (c) HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 54; and (d) a VL comprising the amino acid sequence of SEQ ID NO: 99.

[0382] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from: (a) LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 62; (b) LC-CDR2 comprising the amino acid sequence of SEQ ID NO: 70; and (c) LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 78; and a VH comprising the amino acid sequence of SEQ ID NO: 85.

[0383] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising the following CDRs: HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 54; and LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 78.

[0384] In one aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from: (a) LC- CDR1 comprising the amino acid sequence of SEQ ID NO: 62; (b) LC-CDR2 comprising the amino acid sequence of SEQ ID NO: 70; and (c) LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 78. In one aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VH CDR sequences selected from: (a) HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 38; (b) HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 46; and (c) HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 54.

[0385] In one aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising the following CDRs: (a) HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 38, (b) HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 46; (c) HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 54; (d) LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 62; (e) LC-CDR2 comprising the amino acid sequence of SEQ ID NO: 70; and (f) LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 78.

[0386] In one aspect, the antibody or antigen-binding fragment thereof comprises a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of SEQ ID NO: 85. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody or antigen-binding fragment thereof comprising that sequence retains the ability to bind to antigen. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of SEQ ID NO: 85. In some embodiments, substitutions, insertions, or deletions occur in regions outside the CDRs (e.g., in the FRs). Optionally, the antibody or antigen-binding fragment thereof comprises the VH sequence of the amino acid sequence of SEQ ID NO: 85, including post-translational modifications of that sequence. In particular embodiments, the VH comprises one, two, or three CDRs selected from (a) HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 38, (b) HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 46, and (c) HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 54.

[0387] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain variable domain (VH) having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity with the amino acid sequence of any one of SEQ ID NOs: 1-8. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity includes substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but an antibody or antigen-binding fragment thereof comprising that sequence retains the ability to bind to an antigen. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of any one of SEQ ID NOs: 1-8. In some embodiments, the substitutions, insertions, or deletions occur in regions outside the CDRs (e.g., in the FRs). Optionally, the antibody or antigen-binding fragment thereof comprises a VH sequence of any one of SEQ ID NOs: 1-8, including post-translational modifications of that sequence. In some embodiments, the VH comprises one, two, or three CDRs selected from: (a) a HC-CDR1 comprising an amino acid sequence of SEQ ID NO: 9; (b) a HC-CDR2 comprising an amino acid sequence of SEQ ID NO: 17; and (c) a HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 25.

[0388] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain variable domain (VH) having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity with the amino acid sequence of any one of SEQ ID NOs: 1-8. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity includes substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but an antibody or antigen-binding fragment thereof comprising that sequence retains the ability to bind to an antigen. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of any one of SEQ ID NOs: 1-8. In some embodiments, the substitutions, insertions, or deletions occur in regions outside the CDRs (e.g., in the FRs). Optionally, the antibody or antigen-binding fragment thereof comprises a VH sequence of any one of SEQ ID NOs: 1-8, including post-translational modifications of that sequence. In some embodiments, the VH comprises one, two, or three CDRs selected from: (a) a HC-CDR1 comprising an amino acid sequence of SEQ ID NO: 9; (b) a HC-CDR2 comprising an amino acid sequence of SEQ ID NO: 17; and (c) a HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 25.

[0389] In an aspect, the present disclosure provides an antibody or antigen-binding fragment thereof, comprising one or more variable regions selected from the group consisting of: (a) a VH comprising an amino acid sequence of SEQ ID NO: 86, (b) a VL comprising an amino acid sequence of SEQ ID NO: 100, and (c) a combination thereof.

[0390] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, two, three, four, five, or six CDRs selected from: (a) HC-CDR1 comprising an amino acid sequence of SEQ ID NO: 39; (b) HC-CDR2 comprising an amino acid sequence of SEQ ID NO: 47; (c) HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 54; (d) LC-CDR1 comprising an amino acid sequence of SEQ ID NO: 63; (e) LC-CDR2 comprising an amino acid sequence of SEQ ID NO: 71; and (f) LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 79.

[0391] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VH CDR sequences selected from: (a) HC- CDR1 comprising an amino acid sequence of SEQ ID NO: 39; (b) HC-CDR2 comprising an amino acid sequence of SEQ ID NO: 47; and (c) HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 55; and a VL comprising an amino acid sequence of SEQ ID NO: 100.

[0392] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from: (a) LC- CDR1 comprising an amino acid sequence of SEQ ID NO: 63; (b) LC-CDR2 comprising an amino acid sequence of SEQ ID NO: 71; and (c) LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 79; and a VH comprising an amino acid sequence of SEQ ID NO: 86.

[0393] In an aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising the following CDRs: HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 55; and LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 79.

[0394] In one aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VL CDR sequences selected from: (a) an LC- CDR1 comprising an amino acid sequence of SEQ ID NO: 63; (b) an LC-CDR2 comprising an amino acid sequence of SEQ ID NO: 71; and (c) an LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 79. In one aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising at least one, at least two, or all three VH CDR sequences selected from: (a) an HC-CDR1 comprising an amino acid sequence of SEQ ID NO: 39; (b) an HC-CDR2 comprising an amino acid sequence of SEQ ID NO: 47; and (c) an HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 55.

[0395] In one aspect, the disclosure provides an antibody or antigen-binding fragment thereof, comprising the following CDRs: (a) an HC-CDR1 comprising an amino acid sequence of SEQ ID NO: 39; (b) an HC-CDR2 comprising an amino acid sequence of SEQ ID NO: 47; (c) an HC-CDR3 comprising an amino acid sequence of SEQ ID NO: 55; (d) an LC-CDR1 comprising an amino acid sequence of SEQ ID NO: 63; (e) an LC-CDR2 comprising an amino acid sequence of SEQ ID NO: 71; and (f) an LC-CDR3 comprising an amino acid sequence of SEQ ID NO: 79.

[0396] In one aspect, the antibody or antigen-binding fragment thereof comprises a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of SEQ ID NO: 86. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody or antigen-binding fragment thereof comprising that sequence retains the ability to bind to antigen. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of SEQ ID NO: 86. In some embodiments, substitutions, insertions, or deletions occur in regions outside the CDRs (e.g., in the FRs). Optionally, the antibody or antigen-binding fragment thereof comprises the VH sequence of the amino acid sequence of SEQ ID NO: 86, including post-translational modifications of that sequence. In particular embodiments, the VH comprises one, two, or three CDRs selected from (a) HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 39, (b) HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 47, and (c) HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 55.

[0397] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a heavy chain variable domain (VH) having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 1-6. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (e.g., conservative substitutions), insertions, or deletions relative to the reference sequence, but the antibody, or antigen-binding fragment thereof, comprising that sequence retains the ability to bind to an antigen. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in the amino acid sequence of any one of SEQ ID NOs: 1-6. In some embodiments, the substitutions, insertions, or deletions occur in regions outside the CDRs (e.g., in the FRs). Optionally, the antibody, or antigen-binding fragment thereof, comprises the VH sequence of any one of SEQ ID NOs: 1-6, including post-translational modifications of that sequence. In some embodiments, the VH comprises one, two, or three CDRs selected from: (a) a HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 7; (b) a HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 15; and (c) a HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 23.

[0398] In an aspect, an antibody or antigen-binding fragment thereof is provided, wherein the antibody or antigen-binding fragment thereof comprises a VH as in any of the embodiments provided above and a VL as in any of the embodiments provided above. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 86, and a VL sequence in SEQ ID NO: 100, including post-translational modifications of those sequences. In some embodiments, the antibody or antigen-binding fragment thereof comprises an IgA heavy chain constant region having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 16-21. In some embodiments, the antibody or antigen-binding fragment thereof comprises a kappa light chain constant region of SEQ ID NO: 31.

[0399] Improved IgA antibody properties and functions

[0400] In some embodiments, the antibodies or functional fragments thereof disclosed herein exhibit improved stability relative to their corresponding wild-type IgA antibodies. As used herein, the term "increased stability" includes increased thermal stability and / or reduced aggregation. Enhanced or improved stability can be determined, for example, by accelerated stability studies. Exemplary accelerated stability studies include, but are not limited to, studies characterized by increased storage temperature. A reduction in antibody aggregate formation observed compared to the corresponding WT IgA antibody indicates increased stability. The stability of the antibodies and functional fragments thereof disclosed herein can be tested by measuring the change in the melting temperature transition of the antibody compared to the corresponding wild-type IgA antibody immunoglobulin. In such embodiments, the increased stability or increased thermal stability of the antibody or functional fragment relative to the corresponding WT IgA or functional fragment will become apparent with increasing melting temperature transition. In some embodiments, the antibody or functional fragment thereof has a higher temperature than the corresponding WT IgA antibody. In some embodiments, the melting temperature of the antibody or functional fragment thereof of this disclosure is at least about 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 1.0, or higher than that of the corresponding WT IgA antibody. In some embodiments, the melting temperature of the antibody or functional fragment thereof of this disclosure is at least about 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 12°C, 15°C, or higher than that of the corresponding WT IgA antibody. In some embodiments, the antibody or functional fragment thereof of this disclosure has a melting temperature of at least about 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or higher. In some embodiments, this increased stability is due to the absence of additional disulfide bonds. In particular, the increased stability is due to the absence of additional disulfide bonds in the constant region of the IgA heavy chain. In one embodiment, the CH3 domain of the antibody disclosed herein does not contain additional disulfide bonds compared to the wild-type CH3 domain. In an alternative embodiment, the CH3 domain of the antibody disclosed herein contains at least one disulfide bond compared to the wild-type CH3 domain.

[0401] Other methods for measuring protein aggregation are described in U.S. Patent Application Serial No. 10 / 176,809 and US20030022243A1, the contents of which are incorporated by reference in their entirety. Various analytical techniques for measuring protein stability are available in the art, such as those outlined below: Peptide and Protein Drug Delivery, 247-301, Vincent Lee, ed., Marcel Dekker, Inc., New York, New York, Pubs., 1991; and Jones, A. Adv. Drug Delivery Rev. 10:29-90, 1993. Stability can be measured at a selected temperature for a selected time. Stability is determined qualitatively and / or quantitatively in a variety of different ways, including determining aggregate formation (e.g., using size exclusion chromatography or by measuring turbidity and / or visual inspection). Methods include: evaluating charge heterogeneity using cation exchange chromatography or capillary zone electrophoresis; analysis of amino terminal or carboxy terminal sequence; mass spectrometry analysis; SDS-PAGE analysis of reduced or intact antibody; peptide mapping (e.g., trypsin or LYS-C) analysis; determining biological activity or antigen binding function of the antibody. Instability includes any one or more of: aggregation, oxidation (e.g., Met oxidation), isomerization (e.g., Asp isomerization), clipping / hydrolysis / fragmentation (e.g., fragmentation of hinge region), succinimide formation, unpaired cysteines, N-terminal extensions, C-terminal processing, etc. The term "reduced aggregation" means that the antibody or functional fragment thereof of the present disclosure has reduced aggregation with other antibody molecules and / or other large molecules including serum proteins such as albumin, as compared to the aggregation exhibited by the corresponding WT IgA antibody or variant thereof.

[0402] Increased thermal stability of the antibody relative to the corresponding WT IgA antibody or variant thereof can be determined by differential scanning calorimetry (DSC) using methods standard in the art (see, e.g., Sturtevant, 1987, Annual Review of Physical Chemistry 38:463-488). Increased thermal stability of the antibody relative to the corresponding WT IgA antibody or variant thereof can also be determined using protein thermal unfolding analysis. Alternatively, increased thermal stability of the antibody relative to the corresponding WT IgA antibody or variant thereof can be determined using any application assay for antibodies in which the performance of the antibody is compared to the WT. For example, ADCC on target cells, binding to antigen, or binding to FcaR on immune cells.

[0403] Immunoeffect functions of IgA antibodies

[0404] Provided herein are engineered IgA variants or antibodies comprising one or more modifications within their heavy chain constant region relative to a corresponding WT IgA antibody comprising a WT heavy chain constant region. In some embodiments, the antibodies or functional fragments thereof disclosed herein (e.g., antibodies comprising one or more modific...

Claims

1. An engineered antibody, comprising: a) an antibody antigen binding domain; and b) a constant domain, wherein the constant domain comprises an immunoglobulin A (IgA) heavy chain constant region, wherein the IgA heavy chain constant region comprises an IgA CH2 region, an IgA CH3 region, and an IgA CH1 region, and wherein the IgA heavy chain constant region differs in amino acids from a wild-type IgA heavy chain constant region consisting of the amino acid sequence of SEQ ID NO: 1 by: i) an N45.2G amino acid substitution corresponding to a substitution of Asn at amino acid residue 46 of SEQ ID NO: 109 to Gly; ii) a P124R amino acid substitution corresponding to a substitution of Pro at amino acid residue 101 of SEQ ID NO: 109 to Arg; iii) a C86S amino acid substitution corresponding to a substitution of Cys at amino acid residue 71 of SEQ ID NO: 110 to Ser; iv) an N114T amino acid substitution corresponding to a substitution of Asn at amino acid residue 97 of SEQ ID NO: 110 to Thr; v) an I115L amino acid substitution corresponding to a substitution of Ile at amino acid residue 98 of SEQ ID NO: 110 to Leu; vi) a T116S amino acid substitution corresponding to a substitution of Thr at amino acid residue 99 of SEQ ID NO: 110 to Ser; and vii) a deletion of C-terminal amino acid residues P131-Y148 corresponding to a deletion of amino acid residues spanning Pro at amino acid residue 114 of SEQ ID NO: 111 to Tyr at amino acid residue 131 of SEQ ID NO:

111.

2. An engineered antibody, comprising: a) an antibody antigen binding domain; and b) a constant domain, wherein the constant domain comprises an immunoglobulin A (IgA) heavy chain constant region, wherein the IgA heavy chain constant region comprises an IgA CH2 region, an IgA CH3 region, and an IgA CH1 region, and wherein the IgA heavy chain constant region differs in amino acids from a wild-type IgA heavy chain constant region consisting of the amino acid sequence of SEQ ID NO: 1 by: i) an N45.2G amino acid substitution corresponding to a substitution of Asn at amino acid residue 46 of SEQ ID NO: 109 to Gly; ii) a P124R amino acid substitution corresponding to a substitution of Pro at amino acid residue 101 of SEQ ID NO: 109 to Arg; iii) a C86S amino acid substitution corresponding to a substitution of Cys at amino acid residue 71 of SEQ ID NO: 110 to Ser; iv) an N114T amino acid substitution corresponding to a substitution of Asn at amino acid residue 97 of SEQ ID NO: 110 to Thr; v) an I115L amino acid substitution corresponding to a substitution of Ile at amino acid residue 98 of SEQ ID NO: 110 to Leu; vi) a T116S amino acid substitution corresponding to a substitution of Thr at amino acid residue 99 of SEQ ID NO: 110 to Ser; and vii) a deletion of C-terminal amino acid residues P131-Y148 corresponding to a deletion of amino acid residues spanning Pro at amino acid residue 114 of SEQ ID NO: 111 to Tyr at amino acid residue 131 of SEQ ID NO:

111. v) an I115L amino acid substitution corresponding to a substitution of lie at amino acid residue 98 of SEQ ID NO: 110 to Leu; vi) a T116S amino acid substitution corresponding to a substitution of Thr at amino acid residue 99 of SEQ ID NO: 110 to Ser; and vii) a deletion of C-terminal amino acid residues P131-Y148 corresponding to a deletion of amino acid residues spanning Pro at amino acid residue 114 of SEQ ID NO: 111 to Tyr at amino acid residue 131 of SEQ ID NO: 111; viii) an amino acid substitution selected from N15.2G, N15.2Q, and N15.2T corresponding to an Asn to Gly, Asn to Gin, or Asn to Thr amino acid substitution at amino acid residue 23 of SEQ ID NO: 110, ix) an L15.3I amino acid substitution corresponding to a Leu to Ile amino acid substitution at amino acid residue 24 of SEQ ID NO: 110, x) a T16S amino acid substitution corresponding to a Thr to Ser amino acid substitution at amino acid residue 25 of SEQ ID NO:

110.

3. The engineered antibody of claim 2, wherein the amino acid sequence of the IgA heavy chain constant region is any one of the group consisting of SEQ ID NOs: 18-21.

4. The engineered antibody of claim 1, wherein the amino acid sequence of the IgA heavy chain constant region is SEQ ID NO:

17.

5. The engineered antibody of claim 1, wherein the antibody antigen binding domain comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises a heavy chain complementarity determining region 1 (HC-CDR1), HC-CDR2, and HC-CDR3, the light chain variable region comprises a light chain complementarity determining region 1 (LC-CDR1), LC-CDR2, and LC-CDR3, and wherein (a) the HC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 33, the HC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 41, the HC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 49, the LC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 57, the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 65, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 73; or (b) the HC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 34, the HC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 42, the HC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 50, the LC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 58, the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 66, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO:

74. ​ ​ ​ ​ ​ ​ ​ ​ ​ the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 67, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 75; (c) the HC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 35, the HC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 43, the HC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 51, the LC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 59, the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 67, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 75; (d) the HC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 36, the HC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 44, the HC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 52, the LC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 60, the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 68, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 76; (e) the HC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 37, the HC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 45, the HC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 53, the LC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 61, the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 69, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 77; (f) the HC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 38, the HC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 46, the HC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 54, the LC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 62, the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 70, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 78; (g) the HC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 39, the HC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 47, the HC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 55, the LC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 63, the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 70, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 78; The LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 71, and The LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 79; or (h) The HC-CDR1 sequence is the amino acid sequence of SEQ ID NO:

40. The HC-CDR2 sequence is the amino acid sequence of SEQ ID NO:

48. The HC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 56, and the LC-CDR1 sequence is the amino acid sequence of SEQ ID NO:

64. The LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 72, and The LC-CDR3 sequence is the amino acid sequence of SEQ ID NO:

80.

6. The engineered antibody according to claim 5, wherein: The amino acid sequence of the heavy chain variable region is SEQ ID NO: 4, and the amino acid sequence of the light chain variable region is SEQ ID NO: 5; The amino acid sequence of the heavy chain variable region is SEQ ID NO: 7, and the amino acid sequence of the light chain variable region is SEQ ID NO: 8; The amino acid sequence of the heavy chain variable region is SEQ ID NO: 81, and the amino acid sequence of the light chain variable region is SEQ ID NO: 95; The amino acid sequence of the heavy chain variable region is SEQ ID NO: 82, and the amino acid sequence of the light chain variable region is SEQ ID NO: 96; The amino acid sequence of the heavy chain variable region is SEQ ID NO: 83, and the amino acid sequence of the light chain variable region is SEQ ID NO: 97; The amino acid sequence of the heavy chain variable region is SEQ ID NO: 84, and the amino acid sequence of the light chain variable region is SEQ ID NO: 98; The amino acid sequence of the heavy chain variable region is SEQ ID NO: 85, and the amino acid sequence of the light chain variable region is SEQ ID NO: 99; or The amino acid sequence of the heavy chain variable region is SEQ ID NO: 86, and the amino acid sequence of the light chain variable region is SEQ ID NO:

100.

7. A pharmaceutical composition comprising the engineered antibody according to claim 1, and a pharmaceutically acceptable carrier, diluent, or excipient.

8. An engineered antibody, said engineered antibody comprising: a) Antigen-binding domain; and b) A constant domain, wherein the constant domain comprises the constant region of the immunoglobulin A (IgA) heavy chain. The constant region of the IgA heavy chain includes the IgA CH2 region and the IgA CH3 region. The amino acid differences between the IgA heavy chain constant region and the wild-type IgA heavy chain constant region with the amino acid sequence SEQ ID NO: 1 are as follows: i) an N135Q amino acid substitution corresponding to an Asn to Gin amino acid substitution at amino acid residue 118 of SEQ ID NO: 110, ii) an N45.2G amino acid substitution corresponding to a substitution of Asn at amino acid residue 46 of SEQ ID NO: 109 to Gly; iii) a P124R amino acid substitution corresponding to a substitution of Pro at amino acid residue 101 of SEQ ID NO: 109 to Arg; iv) a C86S amino acid substitution corresponding to a substitution of Cys at amino acid residue 71 of SEQ ID NO: 110 to Ser; v) an N114T amino acid substitution corresponding to a substitution of Asn at amino acid residue 97 of SEQ ID NO: 110 to Thr; vi) an I115L amino acid substitution corresponding to a substitution of Ile at amino acid residue 98 of SEQ ID NO: 110 to Leu; vii) a T116S amino acid substitution corresponding to a substitution of Thr at amino acid residue 99 of SEQ ID NO: 110 to Ser; viii) a deletion of C147 corresponding to a deletion of Cys at amino acid residue 130 of SEQ ID NO: 111; and ix) a deletion of Y148 corresponding to a deletion of Tyr at amino acid residue 131 of SEQ ID NO:

111.

9. The engineered antibody of claim 8, wherein the amino acid sequence of the IgA heavy chain constant region is SEQ ID NO:

16.

10. The engineered antibody of claim 8, wherein the antigen binding domain comprises a heavy chain variable region comprising: a heavy chain complementarity determining region 1 (HC-CDR1), HC-CDR2, and HC- CDR3, and a light chain variable region comprising a light chain complementarity determining region 1 (LC-CDR1), LC-CDR2, and LC-CDR3, and wherein (a) the HC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 33, the HC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 41, the HC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 49, the LC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 57, the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 65, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 73; (b) the HC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 34, the HC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 42, the HC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 50, the LC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 58, the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 66, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 74; the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 67, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 75; (c) the HC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 35, the HC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 43, the HC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 51, the LC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 59, the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 67, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 75; (d) the HC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 36, the HC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 44, the HC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 52, the LC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 60, the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 68, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 76; (e) the HC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 37, the HC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 45, the HC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 53, the LC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 61, the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 69, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 77; (f) the HC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 38, the HC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 46, the HC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 54, the LC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 62, the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 70, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 78; (g) the HC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 39, the HC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 47, the HC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 55, the LC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 63, the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 70, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 78; the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 71, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 79; or (h) the HC-CDR1 sequence is the amino acid sequence of SEQ ID NO: 40, the HC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 48, the HC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 56; the LC- CDR1 sequence is the amino acid sequence of SEQ ID NO: 64, the LC-CDR2 sequence is the amino acid sequence of SEQ ID NO: 71, and the LC-CDR3 sequence is the amino acid sequence of SEQ ID NO: 79; or 11. The engineered antibody of claim 10, wherein: the amino acid sequence of the heavy chain variable region is SEQ ID NO: 4, and the amino acid sequence of the light chain variable region is SEQ ID NO: 5; the amino acid sequence of the heavy chain variable region is SEQ ID NO: 7, and the amino acid sequence of the light chain variable region is SEQ ID NO: 8; the amino acid sequence of the heavy chain variable region is SEQ ID NO: 81, and the amino acid sequence of the light chain variable region is SEQ ID NO: 95; the amino acid sequence of the heavy chain variable region is SEQ ID NO: 82, and the amino acid sequence of the light chain variable region is SEQ ID NO: 96; the amino acid sequence of the heavy chain variable region is SEQ ID NO: 83, and the amino acid sequence of the light chain variable region is SEQ ID NO: 97; the amino acid sequence of the heavy chain variable region is SEQ ID NO: 84, and the amino acid sequence of the light chain variable region is SEQ ID NO: 98; the amino acid sequence of the heavy chain variable region is SEQ ID NO: 85, and the amino acid sequence of the light chain variable region is SEQ ID NO: 99; or the amino acid sequence of the heavy chain variable region is SEQ ID NO: 86, and wherein the amino acid sequence of the light chain variable region is SEQ ID NO:

100.

12. A pharmaceutical composition comprising the engineered antibody of claim 8, and a pharmaceutically acceptable carrier, diluent, or excipient.

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