Anti-ACVR2A antibodies and uses thereof

Abstract

The invention relates to an anti-ACVR2A antibody or an antigen binding fragment thereof and use thereof for inhibiting or antagonizing ACVR2A. The antibodies and antigen-binding fragments are useful in therapeutic methods of treating a disease or disorder associated with ACVR2A or an ACVR2A ligand, which disease or disorder is ameliorated or ameliorated by inhibition of ACVR2A.

Description

[0001] This application is a divisional application of the patent application with application number 202280071417.X filed on September 2, 2022 and invention name “Anti-ACVR2A Antibodies and Their Uses”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the priority benefit of international patent application No. PCT / CN2021 / 116485 filed on September 3, 2021, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0004] Provided herein are molecules capable of binding to ACVR2A, pharmaceutical compositions comprising the molecules, and uses thereof. Background Art

[0005] The activin receptor type 2A (ACVR2A) is a receptor that mediates the functions of activin, as well as other biological activities. Activins are dimeric growth and differentiation factors that belong to the transforming growth factor-β (TGF-β) superfamily of structurally related signaling proteins. Activins signal through a heteromeric complex of receptor serine kinases that includes type I and type II receptors, all of which are transmembrane proteins consisting of a ligand-binding extracellular domain with a cysteine-rich region, a transmembrane domain, and a cytoplasmic domain with serine / threonine specificity. Type I receptors are required for signaling; and type II receptors are required for ligand binding and type I receptor phosphorylation. Although the type II receptor ACVR2A has been implicated in various disease states, there is a need in the art for improved antibody therapies targeting ACVR2A. Summary of the Invention

[0006] In one aspect, provided herein are antibodies or antigen-binding fragments thereof that selectively bind to ACVR2A. In some embodiments, the antibodies provided herein bind to ACVR2A more than ACVR2B. In some embodiments, the antibodies or antigen-binding fragments provided herein have an affinity for ACVR2A that is at least 10 times greater than the affinity for ACVR2B. The present disclosure provides methods for using ACVR2A binding proteins. In some embodiments, ACVR2A binding proteins are capable of inhibiting or blocking the binding of ACVR2A to ACVR2A ligands such as activin A, activin B, GDF8, and GDF11. In some embodiments, provided herein are antibodies or antigen-binding fragments comprising:

[0007] (i) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO: 1, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO: 2;

[0008] (ii) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO: 3, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO: 2;

[0009] (iii) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO:4, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO:2;

[0010] (iv) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO: 5, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO: 6;

[0011] (v) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO:7, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO:6;

[0012] (vi) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO:8, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO:6;

[0013] (vii) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO: 9, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO: 2;

[0014] (viii) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO: 10, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO: 2;

[0015] (ix) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO: 11, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO: 2;

[0016] (x) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 2;

[0017] (xi) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO: 13, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO: 2;

[0018] (xii) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 14;

[0019] (xiii) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO: 15;

[0020] (xiv) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO:7, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO:2;

[0021] (xv) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO: 16;

[0022] (xvi) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO: 17;

[0023] (xvii) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO: 18;

[0024] (xviii) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO:7, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO:19;

[0025] (xix) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO:7, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO:20;

[0026] (xx) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 21;

[0027] (xxi) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 22;

[0028] (xxii) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO:7, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO:23;

[0029] (xxiii) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO:7, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO:24;

[0030] (xxiv) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO:7, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO:6;

[0031] (xxv) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO: 25;

[0032] (xxvi) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 26;

[0033] (xxvii) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 27;

[0034] (xxviii) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO:7, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO:28;

[0035] (xxix) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 29;

[0036] (xxx) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 11, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 30;

[0037] (xxxi) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO:7, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO:31;

[0038] (xxxii) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO:7, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO:32;

[0039] (xxxiii) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO:7, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO:33;

[0040] (xxxiv) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO:9, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO:34;

[0041] (xxxv) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 11, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 35;

[0042] (xxxvi) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 11, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 36;

[0043] (xxxvii) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 11, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 37;

[0044] (xxxviii) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 38;

[0045] (xxxix) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 39;

[0046] (xxxx) HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 40; or

[0047] (xxxxi) HCDR1, HCDR2 and HCDR3 as shown in SEQ ID NO: 9, and LCDR1, LCDR2 and LCDR3 as shown in SEQ ID NO: 41.

[0048] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise:

[0049] (i) HCDR1 comprises the amino acid sequence of SEQ ID NO:42, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:46, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0050] (ii) HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47; or

[0051] (iii) HCDR1 comprises the amino acid sequence of SEQ ID NO: 49, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47; or

[0052] (iv) HCDR1 comprises the amino acid sequence of SEQ ID NO: 50, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 52, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 53; or

[0053] (v) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:52, LCDR2 comprises the amino acid sequence of SEQ ID NO:46, and LCDR3 comprises the amino acid sequence of SEQ ID NO:53; or

[0054] (vi) HCDR1 comprises the amino acid sequence of SEQ ID NO:49, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:52, LCDR2 comprises the amino acid sequence of SEQ ID NO:46, and LCDR3 comprises the amino acid sequence of SEQ ID NO:53; or

[0055] (vii) HCDR1 comprises the amino acid sequence of SEQ ID NO: 54, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47; or

[0056] (viii) HCDR1 comprises the amino acid sequence of SEQ ID NO: 55, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47; or

[0057] (ix) HCDR1 comprises the amino acid sequence of SEQ ID NO: 56, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47; or

[0058] (x) HCDR1 comprises the amino acid sequence of SEQ ID NO: 57, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47; or

[0059] (xi) HCDR1 comprises the amino acid sequence of SEQ ID NO: 58, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47; or

[0060] (xii) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:59, LCDR2 comprises the amino acid sequence of SEQ ID NO:46, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0061] (xiii) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:60, LCDR2 comprises the amino acid sequence of SEQ ID NO:46, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0062] (xiv) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:46, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0063] (xv) HCDR1 comprises the amino acid sequence of SEQ ID NO: 57, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 61, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47; or

[0064] (xvi) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:62, LCDR2 comprises the amino acid sequence of SEQ ID NO:46, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0065] (xvii) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:63, LCDR2 comprises the amino acid sequence of SEQ ID NO:46, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0066] (xviii) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:52, LCDR2 comprises the amino acid sequence of SEQ ID NO:82, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0067] (xix) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:64, LCDR2 comprises the amino acid sequence of SEQ ID NO:46, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0068] (xx) HCDR1 comprises the amino acid sequence of SEQ ID NO: 57, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 65, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47; or

[0069] (xxi) HCDR1 comprises the amino acid sequence of SEQ ID NO: 57, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 66, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47; or

[0070] (xxii) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:59, LCDR2 comprises the amino acid sequence of SEQ ID NO:67, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0071] (xxiii) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:59, LCDR2 comprises the amino acid sequence of SEQ ID NO:68, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0072] (xxiv) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:52, LCDR2 comprises the amino acid sequence of SEQ ID NO:46, and LCDR3 comprises the amino acid sequence of SEQ ID NO:53; or

[0073] (xxv) HCDR1 comprises the amino acid sequence of SEQ ID NO:57, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:59, LCDR2 comprises the amino acid sequence of SEQ ID NO:69, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0074] (xxvi) HCDR1 comprises the amino acid sequence of SEQ ID NO: 57, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 59, LCDR2 comprises the amino acid sequence of SEQ ID NO: 70, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47; or

[0075] (xxvii) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:71, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0076] (xxviii) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:72, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0077] (xxix) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:73, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0078] (xxx) HCDR1 comprises the amino acid sequence of SEQ ID NO: 56, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 74, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47; or

[0079] (xxxi) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:75, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0080] (xxxii) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:67, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0081] (xxxiii) HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:68, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0082] (xxxiv) HCDR1 comprises the amino acid sequence of SEQ ID NO:54, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:76, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0083] (xxxv) HCDR1 comprises the amino acid sequence of SEQ ID NO:56, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:77, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0084] (xxxvi) HCDR1 comprises the amino acid sequence of SEQ ID NO:56, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:78, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0085] (xxxvii) HCDR1 comprises the amino acid sequence of SEQ ID NO:56, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:79, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0086] (xxxviii) HCDR1 comprises the amino acid sequence of SEQ ID NO:57, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:69, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0087] (xxxix) HCDR1 comprises the amino acid sequence of SEQ ID NO:57, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:80, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0088] (xxxx) HCDR1 comprises the amino acid sequence of SEQ ID NO:57, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:70, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47; or

[0089] (xxxxi) HCDR1 comprises the amino acid sequence of SEQ ID NO:54, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:81, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47.

[0090] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise:

[0091] (i) a VH comprising the amino acid sequence of SEQ ID NO: 1, and a VL comprising the amino acid sequence of SEQ ID NO: 2;

[0092] (ii) a VH comprising the amino acid sequence of SEQ ID NO: 3, and a VL comprising the amino acid sequence of SEQ ID NO: 2;

[0093] (iii) a VH comprising the amino acid sequence of SEQ ID NO: 4, and a VL comprising the amino acid sequence of SEQ ID NO: 2;

[0094] (iv) a VH comprising the amino acid sequence of SEQ ID NO: 5, and a VL comprising the amino acid sequence of SEQ ID NO: 6;

[0095] (v) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 6;

[0096] (vi) a VH comprising the amino acid sequence of SEQ ID NO: 8, and a VL comprising the amino acid sequence of SEQ ID NO: 6;

[0097] (vii) a VH comprising the amino acid sequence of SEQ ID NO: 9, and a VL comprising the amino acid sequence of SEQ ID NO: 2;

[0098] (viii) a VH comprising the amino acid sequence of SEQ ID NO: 10, and a VL comprising the amino acid sequence of SEQ ID NO: 2;

[0099] (ix) a VH comprising the amino acid sequence of SEQ ID NO: 11, and a VL comprising the amino acid sequence of SEQ ID NO: 2;

[0100] (x) a VH comprising the amino acid sequence of SEQ ID NO: 12, and a VL comprising the amino acid sequence of SEQ ID NO: 2;

[0101] (xi) a VH comprising the amino acid sequence of SEQ ID NO: 13, and a VL comprising the amino acid sequence of SEQ ID NO: 2;

[0102] (xii) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 14;

[0103] (xiii) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 15;

[0104] (xiv) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 2;

[0105] (xv) a VH comprising the amino acid sequence of SEQ ID NO: 12, and a VL comprising the amino acid sequence of SEQ ID NO: 16;

[0106] (xvi) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 17;

[0107] (xvii) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 18;

[0108] (xviii) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 19;

[0109] (xix) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 20;

[0110] (xx) a VH comprising the amino acid sequence of SEQ ID NO: 12, and a VL comprising the amino acid sequence of SEQ ID NO: 21;

[0111] (xxi) a VH comprising the amino acid sequence of SEQ ID NO: 12, and a VL comprising the amino acid sequence of SEQ ID NO: 22;

[0112] (xxii) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 23;

[0113] (xxiii) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 24;

[0114] (xxiv) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 6;

[0115] (xxv) a VH comprising the amino acid sequence of SEQ ID NO: 12, and a VL comprising the amino acid sequence of SEQ ID NO: 25;

[0116] (xxvi) a VH comprising the amino acid sequence of SEQ ID NO: 12, and a VL comprising the amino acid sequence of SEQ ID NO: 26;

[0117] (xxvii) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 27;

[0118] (xxviii) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 28;

[0119] (xxix) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 29;

[0120] (xxx) a VH comprising the amino acid sequence of SEQ ID NO: 11, and a VL comprising the amino acid sequence of SEQ ID NO: 30;

[0121] (xxxi) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 31;

[0122] (xxxii) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 32;

[0123] (xxxiii) a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 33;

[0124] (xxxiv) a VH comprising the amino acid sequence of SEQ ID NO: 9, and a VL comprising the amino acid sequence of SEQ ID NO: 34;

[0125] (xxxv) a VH comprising the amino acid sequence of SEQ ID NO: 11, and a VL comprising the amino acid sequence of SEQ ID NO: 35;

[0126] (xxxvi) a VH comprising the amino acid sequence of SEQ ID NO: 11, and a VL comprising the amino acid sequence of SEQ ID NO: 36;

[0127] (xxxvii) a VH comprising the amino acid sequence of SEQ ID NO: 11, and a VL comprising the amino acid sequence of SEQ ID NO: 37;

[0128] (xxxviii) a VH comprising the amino acid sequence of SEQ ID NO: 12, and a VL comprising the amino acid sequence of SEQ ID NO: 38;

[0129] (xxxix) a VH comprising the amino acid sequence of SEQ ID NO: 12, and a VL comprising the amino acid sequence of SEQ ID NO: 39;

[0130] (xxxx) a VH comprising the amino acid sequence of SEQ ID NO: 12, and a VL comprising the amino acid sequence of SEQ ID NO: 40; or

[0131] (xxxxi) VH comprising the amino acid sequence of SEQ ID NO:9, and VL comprising the amino acid sequence of SEQ ID NO:41.

[0132] In some embodiments, the antibodies provided herein are IgG.In some embodiments, the antibodies are humanized antibodies.

[0133] In some embodiments, the antibody or antigen-binding fragment thereof is genetically fused or chemically conjugated to the agent.

[0134] In another aspect, provided herein are nucleic acid molecules encoding the antibodies or antigen-binding fragments provided herein.

[0135] In another aspect, provided herein are vectors comprising a nucleic acid molecule encoding an antibody or antigen-binding fragment provided herein.

[0136] In yet another aspect, provided herein is a host cell transformed with a vector encoding an antibody or antigen-binding fragment provided herein.

[0137] In yet another aspect, provided herein is a composition comprising a therapeutically effective amount of an antibody or antigen-binding fragment, a nucleic acid molecule or vector encoding the antibody or antigen-binding fragment provided herein, and a pharmaceutically acceptable excipient.

[0138] In yet another aspect, provided herein is a method for treating a disease or condition in a subject, comprising administering to the subject a composition provided herein. In some embodiments, the method further comprises administering to the subject a second agent. In some embodiments, the disease or condition is associated with ACVR2A. In some embodiments, the disease or condition is associated with an ACVR2A ligand, including activins (such as activin A, activin B, activin AB, activin C, activin AC, and activin E), growth / differentiation factors (GDFs, such as GDF1, GDF3, GDF5, GDF6, GDF7, GDF8, GDF10, and GDF11), bone morphogenetic proteins (BMPs, such as BMP2, BMP4, BMP6, BMP7, BMP8a, BMP8b, BMP9, and BMP10).

[0139] The method of any one of claims 11 to 13, wherein the disease or condition is associated with ACVR2A.

[0140] In some embodiments, the disease or disorder is a musculoskeletal disease or disorder. In some embodiments, the musculoskeletal disease or disorder is selected from the group consisting of anemia, muscle atrophy, spinal muscular atrophy and cancer cachexia. In some embodiments, the disease or disorder is an age-related condition selected from the group consisting of sarcopenia, skin atrophy, muscle wasting, brain atrophy, atherosclerosis, arteriosclerosis, emphysema, osteoporosis, osteoarthritis, immunodeficiency, hypertension, dementia, Huntington's disease, Alzheimer's disease, cataracts, age-related macular degeneration, prostate cancer, stroke, shortened life expectancy, weakness, memory loss, wrinkles, impaired renal function and age-related hearing loss. In some embodiments, the disease or disorder is a metabolic disorder selected from the group consisting of type 2 diabetes, metabolic syndrome, hyperglycemia, non-alcoholic steatohepatitis (NASH) and obesity. In some embodiments, the disease or condition is selected from the group consisting of acute and / or chronic kidney disease or renal failure, liver fibrosis or cirrhosis, pulmonary fibrosis, pulmonary hypertension, cancer, renal fibrosis, Parkinson's disease, amyotrophic lateral sclerosis (ALS), brain atrophy, dementia and anemia, cachexia, sarcoma, bone loss. In some embodiments, the disease or condition is cancer, including ovarian cancer, breast cancer, breast cancer, esophageal cancer, head and neck cancer, lung cancer, melanoma, multiple myeloma, colorectal cancer, hepatocellular carcinoma, pancreatic cancer, endometrial cancer, and gastrointestinal cancer.

[0141] In yet another aspect, provided herein are methods for inhibiting or antagonizing ACVR2A in a cell, comprising contacting the cell with a composition provided herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0142] Figures 1A to 1D : Activin A competition ELISA assay for ACVR2A hits. Anti-ACVR2A hits from a CDRL1 and CDRL2 random mutant phage display library bind to ACVR2A and block the interaction between activin A and ACVR2A. Figure 1A : Anti-ACVR2A Fab hits from the CDRL1 mutant library. Figure 1B : Anti-ACVR2A Fab hits from the CDRL2 mutant library. Figure 1C : Anti-ACVR2A IgG hits from CDRL1 and CDRL2 mutant libraries. Figure 1D : Anti-ACVR2A IgG hits generated using the CDR shuffling approach.

[0143] Figures 2A to 2DFigure 3: Phospho-Smad-dependent reporter gene assay for ACVR2A hits. The ACVR2B knockout stable cell line HEK293T-B1 was transfected with a CAGA-12 luciferase reporter plasmid, and luciferase signaling was tested after overnight incubation with IgG hits and activin A. Figure 2A : Hits J, 21047, 21155, 21169, 21341, 21343, 21366, and 275 inhibit activin A-induced phosphorylated Smad-dependent signaling. Figure 2B and Figure 2C : CDR-shuffled IgG hits NGS-1, NGS-2, NGS-3, NGS-4, NGS-5, 6401, 6403, 3351, 3352, 3353, 3354 and 3355 inhibit activin A-induced phosphorylated Smad-dependent signaling. Figure 2D : Hits J, 275, 21155, 21169, 21341, 21343, 21366, and 6401 inhibit GDF8-induced phosphorylated Smad-dependent signaling.

[0144] Figure 3 : Inhibition of phosphorylated Smad3 by IgG hits in C2C12 cells. The level of Smad3 phosphorylation in satellite C2C12 cells treated for 30 minutes in the presence of activin A (50 ng / ml) alone (PBS) and in combination with ACVE2A Ab hits was quantified using the HTRF protocol. Hits J, 21155, 21169, 21341, 275, and 6401 reduced the level of phosphorylated Smad3 induced by activin A.

[0145] Figures 4A to 4D ACVR2A Ab increases body and muscle weight in mice. Naive SCID mice were treated with ACVR2A Ab LA01 at 20 mg / kg once a week for 28 days. Figure 4A : Body weight growth curves are expressed as mean ± SEM (n = 8). Ab LA01 treatment significantly increased body weight. Figure 4B : Ab LA01 treatment increased tibialis anterior muscle weight. Figure 4C : Changes in inguinal adipose tissue weight. Figure 4D : Changes in epididymal adipose tissue weight. *, P < 0.05 relative to isotype control; **, P < 0.01 relative to control; ***, P < 0.001 relative to control (Student's t test).

[0146] Figures 5A to 5C ACVR2A Ab increases body and muscle weight in wild-type mice. C57BL / 6 mice were treated with ACVR2A Ab LA01 at 10 mg / kg twice a week for 6 weeks. Figure 5A : The body weight growth curves are expressed as mean ± SEM (n = 8). Figure 5B : Ab LA01 increased the weight of tibialis anterior muscle. Figure 5C : Ab LA01 increased the change in gastrocnemius muscle weight. *, P < 0.05 relative to isotype control; **, P < 0.01 relative to control; ***, P < 0.001 relative to control (Student's t-test).

[0147] Figures 6A to 6G ACVR2A Ab promotes erythropoiesis. C57BL / 6 mice were treated with ACVR2A Ab LA01 and / or ACVR2B Trap ACE-536 at 10 mg / kg twice weekly for 2 weeks. After 7 days of treatment, ACVR2B Trap ACE-536 alone or in combination with ACVR2A Ab LA01 increased erythrocyte counts ( Figure 6A ), hemoglobin( Figure 6B ) and hematocrit ( Figure 6C In contrast, single treatment with Ab LA01 for 7 days had little effect on erythrocyte maturation ( Figure 6A 、 Figure 6B and Figure 6C However, treatment with Ab LA01 for 7 days significantly increased reticulocyte counts. After 14 days of treatment, Ab LA01 promoted hematopoiesis, similar to ACE-536, including red blood cell counts ( Figure 6E ), hemoglobin( Figure 6F ) and hematocrit ( Figure 6G Ab LA01 and ACE-536 combination treatment is more effective in hematopoiesis than single agent treatment ( Figures 6E to 6G ). Mean ± SEM are shown. *, P < 0.05 relative to isotype control; **, P < 0.01 relative to control; ***, P < 0.001 relative to control; ****, P < 0.0001 relative to control (one-way ANOVA test).

[0148] 7A to 7EACVR2A Ab attenuates CC14-induced liver fibrosis in a mouse model. Liver fibrosis was induced in 6-8 week old C57 / BL6 mice using intraperitoneal injection of CC14 dissolved in corn oil (1 mL / kg) at a 1:10 ratio twice weekly for 5 weeks. Mice were treated subcutaneously with ACVR2A Ab LA01 or an isotype control antibody at a dose of 20 mg / kg once weekly for 5 weeks. Serum alanine aminotransferase (ALT) and (aspartate aminotransferase) AST were analyzed after two weeks of Ab LA01 treatment. At the end of the study, livers were stained with hematoxylin and eosin (HE) and Masson's trichrome to assess fibrosis, inflammation, and hepatitis, and analyzed using the Knodell tissue activity index (HAI) system. Collagen 3 (Col3) mRNA was analyzed using real-time PCR. Figure 7A : From day 13 to day 35, Ab LA01 significantly increased body weight compared to the isotype control Ab. Figure 7B : Two weeks of treatment with Ab LA01 reduced serum ALT and AST levels in a CC14-induced liver fibrosis model. Figure 7C : Hepatic Col3 expression is reduced after 5 weeks of treatment with Ab LA01. Figure 7D Liver histological analysis showed that Ab LA01 attenuated CC14-induced liver fibrosis and liver injury as assessed by liver fibrosis, portal vein inflammation, and hepatitis lesion scores. Figure 7E Ab LA01 promotes erythropoiesis in a CC14-induced liver fibrosis model. After 24 days of treatment with Ab LA01, RBC count, hemoglobin concentration, and hematocrit values ​​increased. Mean ± SEM values ​​are shown. *, P < 0.05 relative to isotype control; **, P < 0.01 relative to control; ***, P < 0.001 relative to control; ****, P < 0.0001 relative to control (one-way ANOVA test).

[0149] Figures 8A to 8F ACVR2A Ab attenuates liver fibrosis in the HFD (high-fat diet)-CC14 NASH model. 18-19-week-old diet-induced obese (DIO) C57 / BL6 mice were fed an HFD and treated with a low-dose CC14 (25% CC14, 0.5 ml / kg) to induce NSAH. Mice were treated with ACVR2A Ab LA01 for 4 weeks, subcutaneously, at 4 mg / kg or 20 mg / kg twice weekly; the FXR agonist obeticholic acid (OCA) was used as a positive control drug, orally, at 30 mpk once daily. Figure 8A ACVR2A Ab LA01 treatment increased mouse body weight compared to the isotype control group. Figure 8B 、 Figure 8C: Treatment with 20 mg / kg LA01 reduced liver fibrosis scores and Sirius red staining signals. Figure 8D 、 Figure 8E : In the 20 mg / kg LA01-treated group, hepatic collagen gene expression (Col3al) and hepatic aSMA were decreased. Figure 8F : LA01 treatment increases liver weight. Mean ± SEM is shown. *, P < 0.05 relative to isotype control; **, P < 0.01 relative to control; ***, P < 0.001 relative to control (one-way ANOVA test).

[0150] Figures 9A to 9B ACVR2A Ab LA01 inhibits CT26 tumor growth. Balb / C mice (n=8 per treatment) inoculated subcutaneously with 0.5×10E6 viable CT26 cells (day 5) were treated twice weekly with PBS, 10 mg / kg anti-PD-L1 antibody 10F.9G2 intraperitoneally (IP), or 10 mg / kg 10F.9G2 (IP) plus 10 mg / kg ACVR2A Ab LA01 subcutaneously (SC). Figure 9A : Effects of LA01 on tumor growth. Figure 9B : Individual tumor volumes per mouse on day 14. Anti-PD-L1 antibody treatment alone had no efficacy. In contrast, combining ACVR2A Ab LA01 and PD-L1 antibody resulted in no significant effect. Mean ± SEM are shown. **, P < 0.01 (one-way ANOVA test).

[0151] Figure 10 ACVR2A Ab LA01 combined with PD-L1 Ab inhibits LLC tumor growth. C57 / BL6 mice received an intramuscular (hind leg) inoculation of 5×10E5 LLC cells and were treated with PBS, 10 mg / kg PD-L1 Ab FAZ053 intravenously (TV) twice weekly, or a combination of PD-L1 Ab and ACVR2A Ab, 10 mg / kg FAZ053 IV, plus 10 mg / kg ACVR2A Ab SC twice weekly. PD-L1 Ab treatment alone had little effect on tumor growth (Group 2, T / C = 0.62, p = 0.04). Combining ACVR2A Ab LA01 and PD-L1 antibody significantly inhibited tumor growth compared to the control group (Group 3, T / C = 0.41, p < 0.01).

[0152] Figures 11A to 11I ACVR2A Ab LA01 in combination with carboplatin inhibits LLC tumor growth. LLC tumor-bearing C57 / BL6 mice were treated with vehicle control, carboplatin, or a combination of carboplatin and ACVR2A Ab. Figure 11A : Combining ACVR2A AbLA01 and carboplatin significantly inhibited tumor growth compared to carboplatin alone. Figure 11B : Individual tumor volumes in each group, ACVR2A Ab LA01 combination enhances the antitumor effect of carboplatin. Figure 11C 、 Figure 11D and Figure 11E : The percentages of CD8+ T effector cells (Teff), Foxp3+ T regulatory cells (Treg), and the ratio of Teff to Treg in tumors of different groups. Figure 11F : The ratio of Teff to Treg was negatively correlated with tumor volume (R square = 0.30, p value

[0153] =0.0054). Figure 11G 、 Figure 11H and Figure 11I Figure 3: M1 phenotype macrophages, M2 phenotype macrophages, and M1 / M2 ratios in different groups. The M1 / M2 ratio was significantly increased in the combination group. Mean ± SEM is shown. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001; ns, not significant (two-tailed t-test).

[0154] 12A to 12F ACVR2A Ab LA01 attenuated carboplatin-induced anemia. Complete blood count results showed that after carboplatin treatment, white blood cells (WBC) ( Figure 12A ): Neutrophils (NEUT) ( Figure 12B ) and platelets (PLT) ( Figure 12C ) decreased, and ACVR2A Ab treatment significantly increased the number of PLTs. Figure 12D 、 Figure 12E and Figure 12F : Changes in red blood cell (RBC), hemoglobin (HGB), and hematocrit (HCT) in different groups. *, P < 0.05; ***, P < 0.001; ****, p < 0.0001 (one-way ANOVA test).

[0155] 13A to 13D : ACVR2A Ab inhibits tumor growth in the CDX mouse model of ovarian cancer. Figure 13A : Compared with other ovarian cancer cells, TOV-21G cells secrete high levels of activin A in the culture medium. Figure 13B Effect of Ab LA01 on tumor growth. 6-8 week-old female Balb / C nude mice were subcutaneously inoculated in the right flank with 3×10E6 viable TOV-21G cells in 0.1 ml PBS. Single-agent treatment with ACVR2A Ab LA01 significantly inhibited tumor growth compared to the control group (p < 0.001). Figure 13C and Figure 13D : Immunophenotyping of tumor-infiltrating lymphocytes (TILs). More lymphocytes were found to infiltrate the tumors in the LA01 Ab-treated group. Compared with the control group, the number of total NK cells (CD45+CD3-CD49+) and activated NK cells (CD69+ or NKG2D+) in the tumors increased in the LA01 Ab-treated group (p=0.0108, p=0.0076, and p=0.0244, respectively) ( Figure 13C Similarly, there were more macrophages in LA01 Ab treated tumors (p=0.00341) ( Figure 13D ). DETAILED DESCRIPTION

[0156] The present disclosure is based, in part, on novel antibodies that bind to ACVR2A and their superior properties.

[0157] 5.1. Definitions

[0158] The techniques and procedures described or referenced herein include those generally well understood by those skilled in the art and / or commonly employed using conventional methodology, such as, for example, the widely utilized methods described in Sambrook et al., Molecular Cloning: A Laboratory Manual (3rd ed., 2001); Current Protocols in Molecular Biology (Ausubel et al., eds., 2003); Therapeutic Monoclonal Antibodies: From Bench to Clinic (An ed., 2009); Monoclonal Antibodies :Methods and Protocols (Albitar ed., 2010); and Antibody Engineering Volume 1 and Volume 2 (Kontermann and Dübel eds., 2nd edition, 2010). Unless otherwise defined herein, the technical and scientific terms used in this specification have the meanings generally understood by those of ordinary skill in the art. For the purpose of explaining this specification, the following description of terminology will apply, and whenever appropriate, terms used in the singular will also include the plural form, and vice versa. In the case where any description of the terminology set forth conflicts with any document incorporated herein by reference, the description of the term set forth below shall prevail.

[0159] The terms "antibody," "immunoglobulin," or "Ig" are used interchangeably herein and in the broadest sense, and specifically encompass, for example, monoclonal antibodies (including agonists, antagonists, neutralizing antibodies, full-length or intact monoclonal antibodies), antibody compositions with multiple or single epitope specificity, polyclonal or monovalent antibodies, multivalent antibodies, multispecific antibodies formed from at least two intact antibodies (e.g., bispecific antibodies, so long as they exhibit the desired biological activity), single-chain antibodies, and fragments thereof (e.g., domain antibodies), as described below. Antibodies can be human, humanized, chimeric, and / or affinity matured, as well as antibodies from other species (e.g., mouse, rabbit, llama, etc.). The term "antibody" is intended to include B-cell polypeptide products within the immunoglobulin class of polypeptides, which are capable of binding to a specific molecular antigen and are composed of two identical pairs of polypeptide chains, wherein each pair has one heavy chain (about 50 kDa-70 kDa) and one light chain (about 25 kDa), each amino-terminal portion of each chain comprising a variable region of about 100 to about 130 or more amino acids, and each carboxyl-terminal portion of each chain comprising a constant region. See, e.g., Antibody Engineering (Borrebaeck, ed., 2nd ed., 1995); and Kuby, Immunology (3rd edition, 1997). Antibodies also include, but are not limited to, synthetic antibodies, recombinantly produced antibodies, antibodies including those from Camelidae species (e.g., llamas or alpacas) or humanized variants thereof, intrabodies, anti-idiotypic (anti-Id) antibodies, and functional fragments (e.g., antigen-binding fragments) of any of the antibodies described above, which functional portion refers to a portion of an antibody heavy or light chain polypeptide that retains some or all of the binding activity of the antibody from which the fragment is derived. Non-limiting examples of functional fragments (e.g., antigen-binding fragments) include single-chain Fv (scFv) (e.g., including monospecific, bispecific, etc.), Fab fragments, F(ab') fragments, F(ab') fragments, F(ab') fragments, disulfide-linked Fv (dsFv), Fd fragments, Fv fragments, diabodies, triabodies, tetrabodies, and minibodies. In particular, the antibodies provided herein include immunoglobulin molecules and immunologically active portions of immunoglobulin molecules, e.g., an antigen binding domain or molecule containing an antigen binding site that binds an antigen (e.g., one or more CDRs of an antibody). Such antibody fragments can be found, for example, in Harlow and Lane, Antibodies:A Laboratory Manual (1989); Mol,Biology and Biotechnology:A Comprehensive Desk Reference(Myers ed., 1995); Huston et al., 1993, Cell Biophysics 22:189-224; Plückthun and Skerra, 1989, Meth. Enzymol. 178:497-515; and Day, Advanced Immunochemistry (2nd edition, 1990). The antibodies provided herein can be any class (e.g., IgG, IgE, IgM, IgD, and IgA) or any subclass (e.g., IgG1, IgG2, IgG3, IgG4, IgA1, and IgA2) of immunoglobulin molecules. The antibodies can be agonist antibodies or antagonist antibodies. The antibodies can be neither agonist nor antagonist.

[0160] An "antigen" is a structure to which an antibody can selectively bind. A target antigen can be a polypeptide, carbohydrate, nucleic acid, lipid, hapten, or other naturally occurring or synthetic compound. In some embodiments, the target antigen is a polypeptide. In certain embodiments, the antigen is associated with a cell, e.g., present on or in a cell.

[0161] An "intact" antibody is one that comprises an antigen binding site, CL, and at least heavy chain constant regions, CH1, CH2, and CH3. The constant region may comprise a human constant region or an amino acid sequence variant thereof. In certain embodiments, an intact antibody has one or more effector functions.

[0162] The term "binds" or "binding" refers to interactions between molecules, including, for example, to form a complex. The interactions can be, for example, non-covalent interactions, including hydrogen bonds, ionic bonds, hydrophobic interactions, and / or van der Waals interactions. A complex can also include the combination of two or more molecules held together by covalent or non-covalent bonds, interactions, or forces. The strength of the total non-covalent interactions between a single antigen binding site on an antibody and a single epitope of a target molecule (such as an antigen) is the affinity of the antibody or functional fragment for that epitope. The dissociation rate (k) of a binding molecule (e.g., an antibody) for a monovalent antigen is the affinity of the antibody or functional fragment for that epitope. off ) and the association rate (k on ) ratio (k off / k on ) is the dissociation constant K D , which is negatively correlated with affinity. K D The lower the value, the higher the affinity of the antibody. D The value of varies for different antibody and antigen complexes and depends on k on and k off Both. The dissociation constant K of the antibodies provided herein DCan use any method that this paper provides or any other method well known to those skilled in the art to determine.The avidity at a binding site does not always reflect the true interactional intensity between antibody and antigen.When the complex antigen containing a plurality of repeated antigenic determinants (such as multivalent antigens) contacts with the antibody containing a plurality of binding sites, the interaction of antibody and antigen at a site will increase the possibility of reacting at a second site.The intensity of this type of multiple interactions between multivalent antibody and antigen is called as avidity.

[0163] With respect to the binding molecules described herein, terms such as "binds to," "specifically binds to," and similar terms are also used interchangeably herein and refer to a binding molecule or antigen binding domain that specifically binds to an antigen (such as a polypeptide). A binding molecule or antigen binding domain that binds or specifically binds to an antigen can be detected, for example, by immunoassays, Or other techniques known to those skilled in the art to identify. In some embodiments, when a binding molecule or antigen binding domain binds to an antigen with a higher affinity than any cross-reactive antigen, the binding molecule or antigen binding domain binds or specifically binds to the antigen, as determined using experimental techniques such as enzyme-linked immunosorbent assay (ELISA). Typically, a specific or selective reaction will be at least twice the background signal or noise, and can be more than 10 times the background. For a discussion of binding specificity, see, e.g., Fundamental Immunology 332-36 (Paul ed., 2nd ed., 1989). In certain embodiments, the extent of binding of a binding molecule or antigen binding domain to a "non-target" protein is less than about 10% of the binding of the binding molecule or antigen binding domain to its specific target antigen, e.g., as determined by fluorescence activated cell sorting (FACS) analysis. Binding molecules or antigen binding domains that bind to an antigen include binding molecules or antigen binding domains that are capable of binding to the antigen with sufficient affinity such that the binding molecule can be used, for example, as a therapeutic and / or diagnostic agent targeting the antigen. In certain embodiments, the binding molecule or antigen binding domain binds to an antigen with a dissociation constant (K) of less than or equal to 1 μM, 800 nM, 600 nM, 550 nM, 500 nM, 300 nM, 250 nM, 100 nM, 50 nM, 10 nM, 5 nM, 4 nM, 3 nM, 2 nM, 1 nM, 0.9 nM, 0.8 nM, 0.7 nM, 0.6 nM, 0.5 nM, 0.4 nM, 0.3 nM, 0.2 nM, or 0.1 nM. D In certain embodiments, the binding molecule or antigen binding domain binds to an epitope of an antigen that is conserved among antigens from different species.

[0164] In certain embodiments, the binding molecules or antigen binding domains may comprise "chimeric" sequences in which a portion of the heavy and / or light chain is identical or homologous to a corresponding sequence in an antibody derived from a particular species or belonging to a particular antibody class or subclass, while the remainder of the chain is identical or homologous to a corresponding sequence in an antibody derived from another species or belonging to another antibody class or subclass, as well as fragments of such antibodies, so long as they exhibit the desired biological activity (see U.S. Pat. No. 4,816,567; and Morrison et al., 1984, Proc. Natl. Acad. Sci. USA 81:6851-55). Chimeric sequences may include humanized sequences.

[0165] In certain embodiments, binding molecules or antigen-binding domains can comprise the part of " humanized " form of non-human (for example, camelid, murine, non-human primate) antibody, this " humanized " form comprises the sequence from human immunoglobulin (for example, recipient antibody), wherein natural CDR residues are replaced with the residue with required specificity, affinity and ability of the corresponding CDR from non-human species (for example, donor antibody) (such as camelid, mouse, rat, rabbit or non-human primate).In some cases, one or more FR district residues of human immunoglobulin sequence are replaced by corresponding non-human residue.In addition, humanized antibody can be included in the residue that is not found in recipient antibody or in donor antibody.Carry out these modifications to further optimize antibody performance.Humanized antibody heavy chain or light chain can comprise substantially all of at least one or more variable regions, wherein all or substantially all CDRs correspond to those CDRs of non-human immunoglobulin, and all or substantially all FRs are those FRs of human immunoglobulin sequence. In certain embodiments, the humanized antibody will comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. For further details, see Jones et al., Nature 321:522-25 (1986); Riechmann et al., Nature 332:323-29 (1988); Presta, Curr. Op. Struct. Biol. 2:593-96 (1992); Carter et al., Proc. Natl. Acad. Sci. USA 89:4285-89 (1992); U.S. Patents: 6,800,738; 6,719,971; 6,639,055; 6,407,213; and 6,054,297.

[0166] In certain embodiments, a binding molecule or antigen binding domain may comprise a portion of a "fully human antibody" or "human antibody," wherein the terms are used interchangeably herein and refer to an antibody comprising a human variable region and, for example, a human constant region. A binding molecule may comprise an antibody sequence. In a specific embodiment, the term refers to an antibody comprising a variable region and a constant region of human origin. In certain embodiments, a "fully human" antibody may also encompass an antibody that binds to a polypeptide and is encoded by a nucleic acid sequence that is a naturally occurring somatic variant of a human germline immunoglobulin nucleic acid sequence. The term "fully human antibody" includes antibodies having variable and constant regions that correspond to human germline immunoglobulin sequences, as described by Kabat et al. (See Kabat et al., (1991)). Sequences of Proteins of Immunological Interest, Fifth Edition, US Department of Health and Human Services, NIH Publication No. 91-3242). A "human antibody" is an antibody having an amino acid sequence that corresponds to the amino acid sequence of an antibody produced by a human and / or has been produced using any technique for producing human antibodies. This definition of a human antibody specifically excludes humanized antibodies that comprise non-human antigen-binding residues. Human antibodies can be produced using various techniques known in the art, including phage display libraries (Hoogenboom and Winter, J. Mol. Biol. 227:381 (1991); Marks et al., J. Mol. Biol. 222:581 (1991)) and yeast display libraries (Chao et al., Nature Protocols 1:755-68 (2006)). Methods that can also be used to prepare human monoclonal antibodies are described in Cole et al., Monoclonal Antibodies and Cancer Therapy 77 (1985); Boemer et al., J. Immunol. 147(1):86-95 (1991); and van Dijk and van de Winkel, Curr. Opin. Pharmacol. 5:368-74 (2001). Human antibodies can be prepared by administering an antigen to a transgenic animal that has been modified to produce such antibodies in response to antigenic challenge but whose endogenous loci have been disabled, such as mice (for XENOMOUSE TMFor techniques, see, e.g., Jakobovits, Curr. Opin. Biotechnol. 6(5):561-66 (1995); Bruggemann and Taussing, Curr. Opin. Biotechnol. 8(4):455-58 (1997); and U.S. Pat. Nos. 6,075,181 and 6,150,584). For human antibodies generated by human B cell hybridoma technology, see also, e.g., Li et al., Proc. Natl. Acad. Sci. USA 103:3557-62 (2006).

[0167] In certain embodiments, the binding molecules or antigen binding domains may comprise portions of "recombinant human antibodies," wherein the phrase includes human antibodies prepared, expressed, generated, or isolated by recombinant means, such as antibodies expressed using recombinant expression vectors transfected into host cells, antibodies isolated from a recombinant combinatorial human antibody library, antibodies isolated from animals (e.g., mice or cattle) that are transgenic and / or transchromosomal for human immunoglobulin genes (see, e.g., Taylor, LD et al., Nucl. Acids Res. 20:6287-6295 (1992)), or antibodies prepared, expressed, generated, or isolated by any other means involving splicing of human immunoglobulin gene sequences to other DNA sequences. Such recombinant human antibodies may have variable and constant regions derived from human germline immunoglobulin sequences (see Kabat, EA et al., (1991) Sequences of Proteins ofImmunological Interest, 5th ed., US Department of Health and Human Services, NIH Publication No. 91-3242). However, in certain embodiments, such recombinant human antibodies are subjected to in vitro mutagenesis (or, when an animal transgenic for human Ig sequences is used, in vivo somatic mutagenesis) so that the amino acid sequences of the VH and VL regions of the recombinant antibodies are sequences that, while derived from and related to human germline VH and VL sequences, may not naturally exist within the human antibody germline repertoire in vivo.

[0168] In certain embodiments, a binding molecule or antigen-binding domain may comprise a portion of a "monoclonal antibody," wherein the term as used herein refers to an antibody obtained from a substantially homogeneous antibody population, e.g., the individual antibodies comprising the population are identical except for possible naturally occurring mutations or well-known post-translational modifications, such as amino acid isomerization or deamidation, methionine oxidation, or asparagine or glutamine deamidation, which may be present in small amounts, each monoclonal antibody typically recognizing a single epitope on the antigen. In specific embodiments, a "monoclonal antibody," as used herein, is an antibody produced by a single hybridoma or other cell. The term "monoclonal" is not limited to any particular method for preparing an antibody. For example, monoclonal antibodies useful in the present disclosure can be prepared by the hybridoma methodology first described by Kohler et al., Nature 256:495 (1975), or can be prepared in bacterial cells or eukaryotic animal cells or eukaryotic plant cells using recombinant DNA methods (see, e.g., U.S. Patent No. 4,816,567). For example, "monoclonal antibodies" can also be isolated from phage antibody libraries using the techniques described in Clackson et al., Nature 352:624-28 (1991) and Marks et al., J. Mol. Biol. 222:581-97 (1991). Other methods for preparing clonal cell lines and monoclonal antibodies expressed therefrom are well known in the art. See, for example, Short Protocols in Molecular Biology (Ausubel et al. eds., 5th ed., 2002).

[0169] A typical 4-chain antibody unit is a heterotetrameric glycoprotein consisting of two identical light (L) chains and two identical heavy (H) chains. In the case of IgG, the 4-chain unit is generally about 150,000 daltons. Each L chain is connected to the H chain by a covalent disulfide bond, and the two H chains are connected to each other by one or more disulfide bonds depending on the H chain isotype. Each H chain and L chain also has regularly spaced intrachain disulfide bridges. Each H chain has a variable domain (VH) at the N-terminus, followed by three constant domains (CH) of each α chain and γ chain and four CH domains of μ isotype and ε isotype. Each L chain has a variable domain (VL) at the N-terminus, followed by a constant domain (CL) at its other end. VL is aligned with VH, and CL is aligned with the first constant domain (CH1) of the heavy chain. It is believed that specific amino acid residues form an interface between the light chain variable domain and the heavy chain variable domain. The pairing of VH and VL together forms a single antigen binding site. For the structure and properties of different classes of antibodies, see e.g. Basic and Clinical Immunology 71 (Stites et al., eds., 8th ed., 1994); and Immunobiology (Janeway et al. eds., 5th ed., 2001).

[0170] The term "Fab" or "Fab region" refers to the region of an antibody that binds to an antigen. Conventional IgG typically comprises two Fab regions, each located on one of the two arms of the Y-shaped IgG structure. Each Fab region is typically composed of a variable region and a constant region of each heavy chain and light chain. More specifically, the variable region and constant region of the heavy chain in the Fab region are the VH region and the CH1 region, and the variable region and constant region of the light chain in the Fab region are the VL region and the CL region. The VH, CH1, VL, and CL in the Fab region can be arranged in various ways to impart antigen-binding ability according to the present disclosure. For example, the VH region and the CH1 region can be on one polypeptide, and the VL region and the CL region can be on separate polypeptides, similar to the Fab region of conventional IgG. Alternatively, the VH region, the CH1 region, the VL region, and the CL region can all be on the same polypeptide and oriented in different orders, as described in more detail in the following sections.

[0171] The terms "variable region," "variable domain," "V region," or "V domain" refer to a portion of the light or heavy chain of an antibody that is typically located at the amino terminus of the light or heavy chain and has a length of about 120 to 130 amino acids in the heavy chain and about 100 to 110 amino acids in the light chain, and is used for the binding and specificity of each particular antibody to its specific antigen. The variable region of the heavy chain may be referred to as "VH." The variable region of the light chain may be referred to as "VL." The term "variable" refers to the fact that certain segments of the variable region differ extensively in sequence between antibodies. The V region mediates antigen binding and defines the specificity of a particular antibody for its specific antigen.

[0172] However, variability is not evenly distributed across the 110 amino acid span of the variable region. Instead, the V region consists of less variable (e.g., relatively invariant) stretches of about 15 to 30 amino acids called framework regions (FRs), separated by shorter regions of greater variability (e.g., extreme variability) called "hypervariable regions" that are each about 9 to 12 amino acids long. The variable regions of the heavy and light chains each contain four FRs, primarily in a beta-pleated configuration, connected by three hypervariable regions that form loops connecting and in some cases form part of the beta-pleated structure. The hypervariable regions in each chain are held together in close proximity by the FRs and, together with the hypervariable regions from the other chain, contribute to the formation of the antigen-binding site of the antibody (see, e.g., Kabat et al., Sequences of Proteins of

[0173] Immunological Interest(5th edition, 1991)). The constant region is not directly involved in binding the antibody to the antigen, but exhibits various effector functions, such as participation of the antibody in antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). The variable region differs widely in sequence between different antibodies. In specific embodiments, the variable region is a human variable region.

[0174] The term "variable region residue numbering according to Kabat" or "amino acid position numbering as in Kabat" and variations thereof refer to the numbering system for heavy chain variable regions or light chain variable regions as used in the compilation of antibodies in Kabat et al., supra. Using this numbering system, the actual linear amino acid sequence may contain fewer or additional amino acids corresponding to shortening of the FR or CDR of the variable domain or insertion into the FR or CDR of the variable domain. For example, the heavy chain variable domain may include a single amino acid insertion after residue 52 (residue 52a according to Kabat) and three inserted residues after residue 82 (e.g., residues 82a, 82b, and 82c according to Kabat, etc.). For a given antibody, the Kabat numbering of the residues can be determined by aligning the sequence with the "standard" Kabat numbering in an area of ​​homology to the sequence of the antibody. The Kabat numbering system (approximately residues 1-107 for the light chain and residues 1-113 for the heavy chain) is generally used when referring to residues in the variable domain (e.g., Kabat et al., supra). When referring to residues in the constant region of an immunoglobulin heavy chain, the "EU numbering system" or "EU index" is generally used (e.g., the EU index reported in Kabat et al., supra). The "EU index as in Kabat" refers to the residue numbering of the human IgG1 EU antibody. Other numbering systems have been described, for example, AbM, Chothia, Contact, IMGT, and AHon.

[0175] When used to refer to an antibody, the term "heavy chain" refers to a polypeptide chain of about 50 kDa to 70 kDa, wherein the amino terminal portion includes a variable region of about 120 to 130 or more amino acids, and the carboxyl terminal portion includes a constant region. Based on the amino acid sequence of the heavy chain constant region, the constant region can be one of five different types (e.g., isotypes) known as alpha (α), delta (δ), epsilon (ε), gamma (γ), and mu (μ). Different heavy chains have different sizes: α, δ, and γ contain approximately 450 amino acids, while μ and ε contain approximately 550 amino acids. When combined with a light chain, these different types of heavy chains produce antibodies of five well-known classes (e.g., isotypes): IgA, IgD, IgE, IgG, and IgM, including four IgG subclasses, i.e., IgG1, IgG2, IgG3, and IgG4.

[0176] When used to refer to antibodies, the term "light chain" refers to a polypeptide chain of about 25 kDa, wherein the amino terminal portion includes a variable region of about 100 to about 110 or more amino acids, and the carboxyl terminal portion includes a constant region. The approximate length of a light chain is 211 to 217 amino acids. There are two different types, called kappa (κ) or lambda (λ) based on the amino acid sequence of the constant domain.

[0177] As used herein, the terms "hypervariable region", "HVR", "complementarity determining region" and "CDR" are used interchangeably. "CDR" refers to one of the three hypervariable regions (H1, H2 or H3) within the non-framework region of the VH β-fold framework of an immunoglobulin (Ig or antibody), or one of the three hypervariable regions (L1, L2 or L3) within the non-framework region of the VL β-fold framework of an antibody. The CDR1, CDR2 and CDR3 in the VH domain are also referred to as HCDR1, HCDR2 and HCDR3, respectively. The CDR1, CDR2 and CDR3 in the VL domain are also referred to as LCDR1, LCDR2 and LCDR3, respectively. Therefore, CDRs are variable region sequences interspersed within the framework region sequences.

[0178] CDR district is well known to those skilled in the art, and is defined by a well-known numbering system. For example, Kabat complementary determining region (CDR) is based on sequence variability and is the most commonly used (see, for example, Kabat et al., supra; Nick Deschacht et al., J Immunol 2010; 184: 5696-5704). Chothia refers to the position of the structural loop instead (see, for example, Chothia and Lesk, J. Mol. Biol. 196: 901-17 (1987)). When numbering using the Kabat numbering convention, the end of the Chothia CDR-H1 loop changes between H32 and H34, depending on the length of the loop (this is because the Kabat numbering scheme places insertions at H35A and H35B; If 35A and 35B are not present, the loop ends at 32; If only 35A is present, the loop ends at 33; If both 35A and 35B are present, the loop ends at 34). The AbM hypervariable regions represent a compromise between the Kabat CDRs and the Chothia structural loops and are used by Oxford Molecular's AbM antibody modeling software (see, e.g., Antibody Engineering Volume 2 (Kontermann and Dübel eds., 2nd ed., 2010). The "contact" hypervariable regions are based on analysis of available complex crystal structures. Another universal numbering system that has been developed and widely adopted is ImMunoGeneTics (IMGT). (Lafranc et al., Dev. Comp. Immunol. 27(1):55-77(2003)). IMGT is an integrated information system dedicated to immunoglobulins (IG), T cell receptors (TCRs) and major histocompatibility complexes (MHCs) in humans and other vertebrates. In this article, CDR refers to both the amino acid sequence and the position within the light or heavy chain. Since the "position" of CDRs within the structure of the immunoglobulin variable domain is conserved between species and is present in structures called loops, CDR and framework residues are easily identified by using a numbering system that aligns the variable domain sequences according to structural features. This information can be used to transplant and replace CDR residues from immunoglobulins of one species into an acceptor framework, typically from a human antibody. Another numbering system (AHon) has been developed by Honegger and Plückthun, J. Mol. Biol. 309:657-70(2001). The correspondence between numbering systems (including, for example, Kabat numbering and the IMGT unique numbering system) is well known to those skilled in the art (see, for example, Kabat, supra; Chothia and Lesk, supra; Martin, supra; Lefranc et al., supra). Residues from each of these hypervariable regions or CDRs are exemplified in Table 1 below.

[0179] Table 1: Exemplary CDRs according to various numbering systems

[0180]

[0181] In some embodiments, the term "CDR" or "CDR" refers to a specific region of a polypeptide or polypeptide having a specific sequence. In some embodiments, the term "CDR" refers to a ...

[0182] The hypervariable regions may comprise the following "extended hypervariable regions": 24-36 or 24-34 (L1), 46-56 or 50-56 (L2) and 89-97 or 89-96 (L3) in VL, and 26-35 or 26-35A (H1), 50-65 or 49-65 (H2) and 93-102, 94-102 or 95-102 (H3) in VH.

[0183] The term "constant region" or "constant domain" refers to the carboxyl terminal portion of the light chain and the heavy chain, which is not directly involved in the binding of the antibody to the antigen, but exhibits various effector functions, such as interaction with Fc receptors. The term refers to the portion of the immunoglobulin molecule that has a more conserved amino acid sequence relative to the other parts of the immunoglobulin containing the antigen binding site (i.e., the variable region). The constant region may contain the CH1, CH2, and CH3 regions of the heavy chain and the CL region of the light chain.

[0184] The term "framework" or "FR" refers to those variable region residues that flank the CDRs. FR residues are present in, for example, chimeric antibodies, humanized antibodies, human antibodies, domain antibodies, diabodies, linear antibodies, and bispecific antibodies. FR residues are those variable domain residues other than hypervariable region residues or CDR residues.

[0185] The term "Fc region" is used herein to define the C-terminal region of an immunoglobulin heavy chain, including, for example, a native sequence Fc region, a recombinant Fc region, and a variant Fc region. Although the boundaries of the Fc region of an immunoglobulin heavy chain may vary, the human IgG heavy chain Fc region is generally defined as extending from the amino acid residue at position Cys226 or from Pro230 to its carboxyl terminus. The C-terminal lysine (residue 447 according to the EU numbering system) in the Fc region can be removed, for example, during the production or purification of the antibody or by recombinant engineering of nucleic acids encoding the antibody heavy chain. Therefore, the composition of a complete antibody can include an antibody population with all K447 residues removed, an antibody population without the K447 residue removed, and an antibody population with a mixture of antibodies containing and not containing the K447 residue. A "functional Fc region" has the "effector functions" of a native sequence Fc region. Exemplary "effector functions" include C1q binding; CDC; Fc receptor binding; ADCC; phagocytosis; downregulating cell surface receptors (e.g., B cell receptors), etc. In some embodiments, the variant Fc region comprises an amino acid sequence that is different from the amino acid sequence of the native sequence Fc region due to at least one amino acid modification (e.g., substitution, addition or deletion). In certain embodiments, the variant Fc region has at least one amino acid substitution compared to the native sequence Fc region or the Fc region of the parent polypeptide, for example, about one to about ten amino acid substitutions or about one to about five amino acid substitutions in the native sequence Fc region or in the Fc region of the parent polypeptide. The variant Fc region herein can have at least about 80% homology with the native sequence Fc region and / or with the Fc region of the parent polypeptide, or at least about 90% homology thereto, for example, at least about 95% homology thereto.

[0186] As used herein, "epitope" is a term in the art and refers to a local region of an antigen to which a binding molecule (e.g., an antibody) can specifically bind. An epitope can be a linear epitope or a conformational, non-linear, or discontinuous epitope. In the case of a polypeptide antigen, for example, an epitope can be a continuous amino acid of a polypeptide (a "linear" epitope), or an epitope can comprise amino acids from two or more discontinuous regions of a polypeptide (a "conformational," "non-linear," or "discontinuous" epitope). It will be understood by those skilled in the art that, in general, a linear epitope may or may not be dependent on a secondary, tertiary, or quaternary structure. For example, in some embodiments, a binding molecule binds to a group of amino acids, regardless of whether they are folded in a native three-dimensional protein structure. In other embodiments, the binding molecule requires that the amino acid residues constituting the epitope exhibit a specific conformation (e.g., bend, twist, flip, or fold) in order to recognize and bind to the epitope.

[0187] "Percent (%) amino acid sequence identity" and "homology" with respect to peptide, polypeptide or antibody sequences are defined as the percentage of amino acid residues in a candidate sequence that are identical with the amino acid residues in a particular peptide or polypeptide sequence, 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. Alignment for the purpose of determining percent amino acid sequence identity can be achieved in various ways that are within the skill in the art, for example, using publicly available computer software such as BLAST, BLAST-2, ALIGN or MEGALIGN. TM (DNASTAR) software). Those skilled in the art can determine appropriate parameters for measuring alignment, including any algorithms needed to achieve maximal alignment over the full length of the sequences being compared.

[0188] The term "specificity" refers to the selective recognition of a particular epitope of an antigen by an antigen-binding protein. For example, natural antibodies are monospecific. As used herein, the term "multispecific" means that an antigen-binding protein has two or more antigen-binding sites, at least two of which bind to different antigens. As used herein, "bispecific" means that an antigen-binding protein has two different antigen-binding specificities. As used herein, the term "monospecific" antibody means an antigen-binding protein that has one or more binding sites, each of which binds to the same antigen.

[0189] As used herein, the term "valent" refers to the presence of a specific number of binding sites in an antigen-binding protein. For example, a native antibody or full-length antibody has two binding sites and is bivalent. Thus, the terms "trivalent," "tetravalent," "pentavalent," and "hexavalent" refer to the presence of two, three, four, five, and six binding sites, respectively, in an antigen-binding protein.

[0190] The terms "polypeptide," "peptide," and "protein" are used interchangeably herein and refer to polymers of amino acids of any length. The polymer may be linear or branched, it may contain modified amino acids, and it may be interrupted by non-amino acids. The term also encompasses amino acid polymers that have been modified naturally or by intervention. For example, disulfide bond formation, glycosylation, lipidation, acetylation, phosphorylation, or any other manipulation or modification. The definition also includes, for example, polypeptides containing one or more amino acid analogs (including but not limited to non-natural amino acids), as well as other modifications known in the art. It should be understood that because the polypeptides of the present disclosure may be based on antibodies or other members of the immunoglobulin superfamily, in certain embodiments, a "polypeptide" may exist as a single chain or as two or more associated chains.

[0191] "Polynucleotide" or "nucleic acid" are used interchangeably herein to refer to nucleotide polymers of any length and include DNA and RNA. Nucleotides can be deoxyribonucleotides, ribonucleotides, modified nucleotides or bases and / or their analogs, or any substrate that can be incorporated into a polymer by DNA or RNA polymerase or by a synthetic reaction. Polynucleotides may contain modified nucleotides, such as methylated nucleotides and their analogs. As used herein, "oligonucleotide" refers to a short, usually single-stranded, synthetic polynucleotide that is typically, but not necessarily, less than about 200 nucleotides in length. The terms "oligonucleotide" and "polynucleotide" are not mutually exclusive. The above description of polynucleotides is also and fully applicable to oligonucleotides. Cells that produce the binding molecules of the present disclosure can include parent hybridoma cells, as well as bacterial and eukaryotic host cells into which nucleic acids encoding antibodies have been introduced. Unless otherwise indicated, the left-hand end of any single-stranded polynucleotide sequence disclosed herein is the 5' end; the left-hand direction of a double-stranded polynucleotide sequence is referred to as the 5' direction. The direction of 5' to 3' addition of the nascent RNA transcript is called the transcription direction; the sequence region on the DNA chain that has the same sequence as the RNA transcript and is located 5' to the 5' end of the RNA transcript is called the "upstream sequence"; the sequence region on the DNA chain that has the same sequence as the RNA transcript and is located 3' to the 3' end of the RNA transcript is called the "downstream sequence".

[0192] "Isolated nucleic acid" is a nucleic acid (e.g., RNA, DNA, or mixed nucleic acid) that is substantially separated from other genomic DNA sequences and naturally accompanying proteins or complexes (such as ribosomes and polymerases) of native sequences. "Isolated" nucleic acid molecules are nucleic acid molecules separated from other nucleic acid molecules present in the natural source of this nucleic acid molecule. In addition, "isolated" nucleic acid molecules (such as cDNA molecules) can be substantially free of other cellular materials or culture medium when produced by recombinant technology, or can be substantially free of chemical precursors or other chemical substances when chemically synthesized. In a specific embodiment, one or more nucleic acid molecules encoding antibodies as described herein are separated or purified. This term includes nucleic acid sequences removed from its natural environment, and includes recombinant or cloned DNA isolates and chemically synthesized analogs or analogs synthesized biologically by heterologous systems. Substantially pure molecules can include the isolated form of this molecule. Specifically, "isolated" nucleic acid molecules encoding antibodies as described herein are nucleic acid molecules identified and isolated from at least one contaminating nucleic acid molecule that is typically associated with it in the environment in which it is produced.

[0193] Unless otherwise indicated, a "nucleotide sequence encoding an amino acid sequence" includes all nucleotide sequences that are degenerate versions of each other and that encode the same amino acid sequence. The phrase "nucleotide sequence encoding a protein or RNA" may also include introns, to the extent that a nucleotide sequence encoding a protein may contain introns in some forms.

[0194] The term "control sequence" refers to DNA sequences necessary for the expression of an operably linked coding sequence in a particular host organism. For example, control sequences suitable for use in prokaryotes include a promoter, optionally an operator sequence, and a ribosome binding site. Eukaryotic cells are known to utilize promoters, polyadenylation signals, and enhancers.

[0195] As used herein, the term "operably linked" and similar phrases (e.g., gene fusions), when used to refer to nucleic acids or amino acids, refer to the operable connection of nucleic acid sequences or amino acid sequences that are in a functional relationship with each other, respectively. For example, operably linked promoters, enhancer elements, open reading frames, 5' and 3' UTRs, and terminator sequences result in the accurate production of nucleic acid molecules (e.g., RNA). In some embodiments, the operably linked nucleic acid elements result in the transcription of the open reading frame and ultimately result in the production of polypeptides (i.e., expression of the open reading frame). As another example, an operably linked peptide is one in which functional domains are placed at an appropriate distance from each other to impart the intended function of each domain.

[0196] The term "vector" refers to a material for carrying or including a nucleic acid sequence (including a nucleic acid sequence encoding a binding molecule as described herein (e.g., an antibody)) so that the nucleic acid sequence is introduced into the host cell. Suitable vectors for use include, for example, expression vectors, plasmids, phage vectors, viral vectors, episomes, and artificial chromosomes, which can include a selection sequence or a marker operable for stable integration into the host cell chromosome. In addition, the vector can include one or more selective marker genes and appropriate expression control sequences. The selective marker gene that can be included, for example, provides resistance to antibiotics or toxins, supplements nutritional deficiencies, or supplies key nutrients that are not in the culture medium. Expression control sequences can include constitutive and inducible promoters, transcription enhancers, transcription terminators, etc., which are well known in the art. When co-expressing two or more nucleic acid molecules (e.g., antibody heavy chain and light chain or antibody VH and VL), two nucleic acid molecules can be inserted into, for example, a single expression vector or separate expression vectors. For single vector expression, the encoding nucleic acid can be operably linked to a common expression control sequence or be connected to different expression control sequences, such as an inducible promoter and a constitutive promoter. The introduction of nucleic acid molecules into host cells can be confirmed using methods well known in the art. Such methods include, for example, nucleic acid analysis (such as Northern blots or polymerase chain reaction (PCR) amplification of mRNA), immunoblotting of gene product expression, or other suitable analytical methods for testing the expression of the introduced nucleic acid sequence or its corresponding gene product. It will be understood by those skilled in the art that nucleic acid molecules are expressed in an amount sufficient to produce the desired product, and it will also be understood that expression levels can be optimized using methods well known in the art to obtain sufficient expression.

[0197] As used herein, the term "host" refers to an animal, such as a mammal (eg, a human).

[0198] As used herein, the term "host cell" refers to a specific subject cell that can be transfected with a nucleic acid molecule, as well as the progeny or potential progeny of such a cell. The progeny of such a cell may differ from the parent cell that was transfected with the nucleic acid molecule due to mutations or environmental influences that may occur in subsequent generations or due to integration of the nucleic acid molecule into the host cell genome.

[0199] As used herein, the term "transfected" or "transformed" or "transduced" refers to the process of transferring or introducing exogenous nucleic acid into a host cell. A "transfected" or "transformed" or "transduced" cell is a cell that has been transfected, transformed, or transduced with exogenous nucleic acid. Such cells include the primary subject cell and its progeny.

[0200] As used herein, the term "pharmaceutically acceptable" means approved by a regulatory agency of the Federal or a state government, or in United States Pharmacopoeia, European Pharmacopoeiaor other generally recognized pharmacopoeia for use in animals and more particularly in humans.

[0201] " excipient " means pharmaceutically acceptable material, composition or vehicle, such as liquid or solid filler, diluent, solvent or encapsulating material. Excipient includes for example encapsulating material or additive, such as absorption accelerator, antioxidant, adhesive, buffer, carrier, coating agent, coloring agent, diluent, disintegrant, emulsifier, swelling agent, filler, flavoring agent, wetting agent, lubricant, spices, preservative, propellant, releasing agent, bactericide, sweetener, solubilizing agent, wetting agent and their mixture.Term " excipient " can also refer to diluent, adjuvant (for example, Freund's adjuvant (complete or incomplete)) or vehicle.

[0202] In some embodiments, the excipient is a pharmaceutically acceptable excipient. Examples of pharmaceutically acceptable excipients include buffers such as phosphate, citrate, and other organic acids; antioxidants including ascorbic acid; low molecular weight (e.g., less than about 10 amino acid residues) polypeptides; proteins such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, arginine, or lysine; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrins; chelating agents such as EDTA; sugar alcohols such as mannitol or sorbitol; salt-forming counterions such as sodium; and / or nonionic surfactants such as TWEEN®. TM , polyethylene glycol (PEG) and PLURONICS TM Other examples of pharmaceutically acceptable excipients are described in Remington and Gennaro, Remington ' s Pharmaceutical Sciences (18th edition, 1990).

[0203] In one embodiment, each component is "pharmaceutically acceptable" in the sense of being compatible with the other ingredients of the pharmaceutical formulation and suitable for use in contact with the tissues or organs of humans and animals without excessive toxicity, irritation, allergic response, immunogenicity, or other problems or complications commensurate with a reasonable benefit / risk ratio. See, e.g., Lippincott Williams & Wilkins: Philadelphia, PA, 2005; Handbook of Pharmaceutical Excipients, 6th ed.; Rowe et al., eds.; the Pharmaceutical Press and the American Pharmaceutical Association: 2009; Handbook of Pharmaceutical Additives, 3rd ed.; Ash and Ash, eds.; Gower Publishing Company: 2007; Pharmaceutical Preformulation and Formulation, 2nd ed.; Gibson, ed.; CRC Press, Inc.: Boca Raton, FL, 2009. In some embodiments, a pharmaceutically acceptable excipient is nontoxic to the cells or mammals to which it is exposed at the dosages and concentrations employed. In some embodiments, the pharmaceutically acceptable excipient is a pH buffered aqueous solution.

[0204] In some embodiments, excipient is a sterile liquid, such as water and oil, including oils from petroleum, animal, plant or synthetic sources, such as peanut oil, soybean oil, mineral oil, sesame oil, etc. When administering compositions (for example, pharmaceutical compositions) intravenously, water is an exemplary excipient. Saline solutions and glucose and glycerol aqueous solutions can also be used as liquid excipients, particularly for injectable solutions. Excipient can also include starch, glucose, lactose, sucrose, gelatin, malt, rice, flour, chalk, silica gel, sodium stearate, glyceryl monostearate, talc, sodium chloride, skim milk powder, glycerol, propylene, ethylene glycol, water, ethanol, etc. If desired, the composition can also contain a small amount of wetting agent or emulsifier or pH buffer. Composition can take the form of solution, suspension, emulsion, tablet, pill, capsule, powder, sustained release formulations, etc. Oral compositions (including preparations) can include standard excipients, such as pharmaceutical grade mannitol, lactose, starch, magnesium stearate, sodium saccharin, cellulose, magnesium carbonate, etc.

[0205] Compositions (including pharmaceutical compounds) can contain, for example, the binding molecule (eg, antibody) in isolated or purified form and a suitable amount of an excipient.

[0206] As used herein, the term "effective amount" or "therapeutically effective amount" refers to an amount of an antibody, or a therapeutic molecule comprising an agent and an antibody, or a pharmaceutical composition provided herein sufficient to produce a desired result.

[0207] The terms "subject" and "patient" are used interchangeably. As used herein, in certain embodiments, the subject is a mammal, such as a non-primate or primate (e.g., a human). In specific embodiments, the subject is a human. In one embodiment, the subject is a mammal (e.g., a human) diagnosed with a disease or condition. In another embodiment, the subject is a mammal (e.g., a human) at risk of developing a disease or condition.

[0208] "Administer" or "administration" refers to the act of injecting or otherwise physically delivering a substance present outside the body into a patient's body, such as by mucosal, intradermal, intravenous, intramuscular delivery, and / or any other physical delivery method described herein or known in the art.

[0209] As used herein, the terms "treat," "treatment," and "treating" refer to a reduction or improvement in the progression, severity, and / or duration of a disease or condition resulting from the administration of one or more therapies. Treatment can be determined by assessing whether one or more symptoms associated with the underlying condition have been reduced, alleviated, and / or relieved, such that improvement is observed in the patient, notwithstanding that the patient may still be afflicted with the underlying condition. The term "treat" includes both the management and the amelioration of a disease. The terms "manage," "managing," and "management" refer to the beneficial effects that a subject obtains from a therapy that does not necessarily result in a cure for the disease.

[0210] The terms "prevent," "preventing," and "prevention" refer to reducing the likelihood of the onset (or recurrence) of a disease, disorder, condition, or associated symptoms (eg, diabetes or cancer).

[0211] As used herein, "delaying" the development of cancer means postponing, hindering, slowing, retarding, stabilizing, and / or delaying the progression of the disease. This delay can be of varying lengths of time, depending on the history of the disease and / or the individual being treated. As will be apparent to one skilled in the art, a sufficient or significant delay can actually encompass prevention, in that the individual does not develop the disease.

[0212] An approach to "delaying" cancer development is one that reduces the likelihood of disease development in a given time frame and / or reduces the extent of the disease in a given time frame when compared to not using the approach. Such comparisons are typically based on clinical studies using a statistically significant number of individuals. Cancer development can be detected using standard methods, including but not limited to computerized axial tomography (CAT scan), magnetic resonance imaging (MRI), abdominal ultrasound, coagulation tests, arteriography, or biopsy. Development can also refer to the progression of a cancer that may not initially be detected, and includes onset, recurrence, and onset.

[0213] As used herein, "ACVR2A-associated disease or condition" refers to a disease or condition involving cells or tissues in which ACVR2A is expressed or overexpressed. In some embodiments, an ACVR2A-associated disease or condition comprises cells in which ACVR2A is aberrantly expressed. In other embodiments, an ACVR2A-associated disease or condition comprises cells in which or on which ACVR2A lacks at least one of its activities.

[0214] As used herein, "ACVR2A ligand-associated disease or condition" refers to a disease or condition involving cells or tissues in which one or more ACVR2A ligands are expressed or overexpressed, including activins (such as activin A, activin B, activin AB, activin C, activin AC, and activin E), growth / differentiation factors (GDFs, such as GDF1, GDF3, GDF5, GDF6, GDF7, GDF8, GDF10, and GDF11), and bone morphogenetic proteins (BMPs, such as BMP2, BMP4, BMP6, BMP7, BMP8a, BMP8b, BMP9, and BMP10). In some embodiments, an ACVR2A ligand-associated disease or condition involves cells in which one or more ACVR2A ligands are abnormally expressed. In other embodiments, an ACVR2A ligand-associated disease or condition involves cells in which one or more ACVR2A ligands lack at least one of their activities. In other embodiments, the ACVR2A ligand-associated disease or disorder comprises abnormal levels of one or more ACVR2A ligand proteins in serum, plasma, or blood.

[0215] The terms "about" and "approximately" mean within 20%, within 15%, within 10%, within 9%, within 8%, within 7%, within 6%, within 5%, within 4%, within 3%, within 2%, within 1% or less of a given value or range.

[0216] As used in this disclosure and the claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0217] It should be understood that wherever herein an embodiment is described using the term "comprising," other similar embodiments described using "consisting of" and / or "consisting essentially of" are also provided. It should also be understood that wherever herein an embodiment is described using the phrase "consisting essentially of," other similar embodiments described using "consisting of" are also provided.

[0218] The term “between” as used in phrases such as “between A and B” or “between AB” refers to a range that includes both A and B.

[0219] The term "and / or" as used herein in phrases such as "A and / or B" is intended to include both A and B. A or B; A (alone); and B (alone). Likewise, the term "and / or" as used in phrases such as "A, B and / or C" is intended to include both A and B.

[0220] "Or" is intended to encompass each of the following embodiments: A, B, and C; A, B, or C; A or C; A or B; B or C; A and C; A and B; B and C; A (alone); B (alone); and C (alone).

[0221] ACVR2A Binding Molecules

[0222] 5.2.1. Antibodies that bind to ACVR2A

[0223] In one aspect, provided herein are antibodies capable of binding to ACVR2A. ACVR2A is a receptor that mediates the function of activin, a member of the transforming growth factor-β (TGF-β) superfamily that is involved in a variety of biological processes. ACVR2A is a transmembrane serine-threonine kinase receptor that mediates signal transduction by forming heterodimeric complexes with various combinations of type I and type II receptors and ligands in a cell-specific manner. Type II receptors are primarily involved in ligand binding and include an extracellular ligand binding domain, a transmembrane domain, and a cytoplasmic serine-threonine kinase domain. The nucleic acid and amino acid sequences of ACVR2A are known (see GCID: GC02P 147844, HGNC: 173, NCBI Entrez Gene: 92, Ensembl: ENSG00000121989, 102581 and UniProtKB / Swiss-Prot: P27037) In some embodiments, the antibodies provided herein bind to human ACVR2A. In some embodiments, the anti-ACVR2A antibodies provided herein modulate one or more ACVR2A activities. In some embodiments, the anti-ACVR2A antibodies provided herein are antagonist antibodies.

[0224] In one embodiment, the antibodies according to the present disclosure are ACVR2A antagonists that have no or low agonist activity. In another embodiment, the antibodies or functional fragments comprising an antigen-binding portion bind to the target protein ACVR2A and reduce the binding of activin A to ACVR2A to basal levels. In one aspect of this embodiment, the antibody or functional fragment reduces the amount of activin A bound to ACVR2A. In another aspect of this embodiment, the antibody or functional fragment completely prevents activin A from binding to ACVR2A. In another embodiment, the antibody or functional fragment inhibits Smad activation. As determined according to methods known in the art and described herein, an antibody that inhibits one or more of these ACVR2A functional properties (e.g., biochemical, immunochemical, cellular, physiological, or other biological activities, etc.) will be understood to be associated with a statistically significant reduction in a specific activity relative to that observed in the absence of the antibody (e.g., or in the presence of a control antibody of irrelevant specificity). In some embodiments, antibodies that inhibit ACVR2A activity achieve such a statistically significant reduction of at least 10%, at least 50%, 80%, or 90% of the measured parameter, and in certain embodiments, the antibodies of the present disclosure can inhibit greater than 95%, 98%, or 99% of ACVR2A functional activity.

[0225] In one embodiment, the antibodies of the present disclosure do not cross-react with ACVR2A-related proteins, and more specifically do not cross-react with human ACVR2B (NP_001607.1, GI:4501897). In one embodiment, the antibodies of the present disclosure bind to ACVR2A but not ACVR2B. In one embodiment, the antibodies of the present disclosure bind to ACVR2A with 10 times the affinity that they bind to ACVR2B. In one embodiment, the antibodies of the present disclosure bind to ACVR2A with 20 times the affinity that they bind to ACVR2B. In one embodiment, the antibodies of the present disclosure bind to ACVR2A with 30 times the affinity that they bind to ACVR2B. In one embodiment, the antibodies of the present disclosure bind to ACVR2A with 40 times the affinity that they bind to ACVR2B. In one embodiment, the antibodies of the present disclosure bind to ACVR2A with 50 times the affinity that they bind to ACVR2B. In one embodiment, the antibodies of the present disclosure bind to ACVR2A with an affinity 60 times greater than that of ACVR2B. In one embodiment, the antibodies of the present disclosure bind to ACVR2A with an affinity 70 times greater than that of ACVR2B. In one embodiment, the antibodies of the present disclosure bind to ACVR2A with an affinity 80 times greater than that of ACVR2B. In one embodiment, the antibodies of the present disclosure bind to ACVR2A with an affinity 90 times greater than that of ACVR2B. In one embodiment, the antibodies of the present disclosure bind to ACVR2A with an affinity 100 times greater than that of ACVR2B. In one embodiment, the antibodies of the present disclosure bind to ACVR2A with an affinity greater than 100 times greater than that of ACVR2B, such as 500 times or 1000 times greater than that of ACVR2B.

[0226] In some embodiments, the anti-ACVR2A antibodies provided herein are expressed at ≤1 μM, ≤100 nM, ≤10 nM, ≤1 nM, ≤0.1 nM, ≤0.01 nM, or ≤0.001 nM (e.g., 10 -8 M or smaller, such as 10 -8 M to 10 -13 M, for example 10 -9 M to 10 -13 The dissociation constant (K D ) binds to ACVR2A (e.g., human ACVR2A). A variety of methods for measuring binding affinity are known in the art, any of which can be used for the purposes of the present disclosure, including by RIA, for example, with a Fab form of the antibody of interest and its antigen (Chen et al., 1999, J. Mol Biol 293:865-81); by biolayer interferometry (BLI) or surface plasmon resonance (SPR) assays, by (Using e.g. Red96 system) or through (Using e.g. TM-2000 or TM-3000). “On-rate” or “rate of association” or “association rate” or “kon” may also be measured using the same biolayer interferometry (BLI) or surface plasmon resonance (SPR) techniques described above using, for example, Red96, TM-3000 or TM-8000 system to determine.

[0227] In some embodiments, the anti-ACVR2A antibodies provided herein are those described in Section 7 below. Thus, in some embodiments, the antibodies provided herein comprise one or more CDR sequences of any one of SEQ ID NOs: 1 to 41. CDR sequences can be determined according to well-known numbering systems. In some embodiments, CDRs are numbered according to IMGT. In some embodiments, CDRs are numbered according to Kabat. In some embodiments, CDRs are numbered according to AbM. In other embodiments, CDRs are numbered according to Chothia. In other embodiments, CDRs are numbered according to Contact. In some embodiments, the anti-ACVR2A antibodies are humanized. In some embodiments, the anti-ACVR2A antibodies comprise an acceptor human framework, such as a human immunoglobulin framework or a human consensus framework.

[0228] In some embodiments, the anti-ACVR2A antibodies provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 1. In some embodiments, the anti-ACVR2A antibodies provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 3. In some embodiments, the anti-ACVR2A antibodies provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 4. In some embodiments, the anti-ACVR2A antibodies provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 5. In some embodiments, the anti-ACVR2A antibodies provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 7. In some embodiments, the anti-ACVR2A antibodies provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 8. In some embodiments, the anti-ACVR2A antibodies provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 9.

[0229] ACVR2A antibodies comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 9. In some embodiments, anti-ACVR2A antibodies provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 10.

[0230] In some embodiments, the anti-ACVR2A antibodies provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 11. In some embodiments, the anti-ACVR2A antibodies provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 12. In some embodiments, the anti-ACVR2A antibodies provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 13.

[0231] The ACVR2A antibody comprises HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 13. CDR sequences can be identified according to well-known numbering systems or combinations thereof. In some embodiments, the CDRs are numbered according to IMGT. In some embodiments, the CDRs are numbered according to Kabat. In some embodiments, the CDRs are numbered according to AbM. In other embodiments, the CDRs are numbered according to Chothia. In other embodiments, the CDRs are numbered according to Contact.

[0232] In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 2. In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 6. In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 7.

[0233] ACVR2A antibodies comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 14. In some embodiments, anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 15.

[0234] In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 16. In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 17. In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 18.

[0235] ACVR2A antibodies comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 18. In some embodiments, anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 19.

[0236] In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 20. In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 21. In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 22.

[0237] ACVR2A antibodies comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 22. In some embodiments, anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 23.

[0238] In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 24. In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 25. In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 26.

[0239] ACVR2A antibodies comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 26. In some embodiments, anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 27.

[0240] In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 28. In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 29.

[0241] ACVR2A antibodies comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 30. In some embodiments, anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 31.

[0242] In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 32. In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 33. In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 34.

[0243] ACVR2A antibodies comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 34. In some embodiments, anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 35.

[0244] In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 36. In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 37.

[0245] ACVR2A antibodies comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 38. In some embodiments, anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 39.

[0246] LCDR3. In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as set forth in SEQ ID NO:40. In some embodiments, the anti-ACVR2A antibodies provided herein comprise LCDR1, LCDR2, and LCDR3 as set forth in SEQ ID NO:41. CDR sequences can be identified according to well-known numbering systems or combinations thereof. In some embodiments, the CDRs are numbered according to IMGT. In some embodiments, the CDRs are numbered according to Kabat. In some embodiments, the CDRs are numbered according to AbM. In other embodiments, the CDRs are numbered according to Chothia. In other embodiments, the CDRs are numbered according to Contact.

[0247] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 1, and LCDR1, LCDR2, and LCDR3 as set forth in SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 3, and LCDR1, LCDR2, and LCDR3 as set forth in SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 4, and LCDR1, LCDR2, and LCDR3 as set forth in SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 5, and LCDR1, LCDR2, and LCDR3 as set forth in SEQ ID NO: 6. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 7, and LCDR1, LCDR2, and LCDR3 as set forth in SEQ ID NO: 6. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 8, and LCDR1, LCDR2, and LCDR3 as set forth in SEQ ID NO: 6. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 9, and LCDR1, LCDR2, and LCDR3 as set forth in SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 10, and LCDR1, LCDR2, and LCDR3 as set forth in SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 11, and LCDR1, LCDR2, and LCDR3 as set forth in SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 12, and LCDR1, LCDR2, and LCDR3 as set forth in SEQ ID NO: 2.In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 13, and LCDR1, LCDR2, and LCDR3 as set forth in SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as set forth in SEQ ID NO: 7, and LCDR1, LCDR2, and LCDR3 as set forth in SEQ ID NO: 14.

[0248] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and

[0249] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and

[0250] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2, and

[0251] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and

[0252] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 18.

[0253] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and

[0254] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and

[0255] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2, and

[0256] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2, and

[0257] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 23.

[0258] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 24.

[0259] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and

[0260] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2, and

[0261] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2, and

[0262] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 27.

[0263] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 28.

[0264] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and

[0265] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 11, and LCDR1, LCDR2, and

[0266] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and

[0267] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and

[0268] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 7, and LCDR1, LCDR2, and

[0269] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 9, and LCDR1, LCDR2, and

[0270] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 11, and LCDR1, LCDR2, and

[0271] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 11, and LCDR1, LCDR2, and

[0272] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 11, and LCDR1, LCDR2, and

[0273] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2, and

[0274] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2, and

[0275] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 12, and LCDR1, LCDR2, and

[0276] LCDR3. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise HCDR1, HCDR2, and HCDR3 as shown in SEQ ID NO: 9, and LCDR1, LCDR2, and LCDR3 as shown in SEQ ID NO: 41. CDR sequences can be determined according to well-known numbering systems or combinations thereof. In some embodiments, CDRs are numbered according to IMGT. In some embodiments, CDRs are numbered according to Kabat. In some embodiments, CDRs are numbered according to AbM. In other embodiments, CDRs are numbered according to Chothia. In other embodiments, CDRs are numbered according to Contact.

[0277] In other embodiments, provided herein are antibodies that bind to ACVR2A comprising a HCDR1 comprising an amino acid sequence that is at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to any one of SEQ ID NOs: 42, 48, 49, 50, 54, 55, 56, 57, and 58; (ii) a HCDR2 comprising an amino acid sequence that is at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to any one of SEQ ID NOs: 43 and 51; (iii) a HCDR3 comprising an amino acid sequence that is at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to any one of SEQ ID NOs: 94, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to any one of SEQ ID NOs: 45, 52, 59, 60, 61, 62, 63 and 64; (v) a HCDR3 comprising an amino acid sequence that is at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to any one of SEQ ID NOs: 45, 52, 59, 60, 61, 62, 63 and 64; NO: 46, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81 and 82 having an amino acid sequence that is at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical; and / or (vi) containing an amino acid sequence that is identical to SEQ In some embodiments, the anti-ACVR2A antibody is humanized. In some embodiments, the anti-ACVR2A antibody comprises an acceptor human framework, such as a human immunoglobulin framework or a human consensus framework.

[0278] In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 42, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 49, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 50, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 52, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 53. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO:48, HCDR2 comprises the amino acid sequence of SEQ ID NO:51, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:52, LCDR2 comprises the amino acid sequence of SEQ ID NO:46, and LCDR3 comprises the amino acid sequence of SEQ ID NO:53.In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 49, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 52, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 53. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 54, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 55, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 56, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO:57, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:46, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47.In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 58, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 59, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 60, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 57, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 61, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47.In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 62, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 63, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 52, LCDR2 comprises the amino acid sequence of SEQ ID NO: 82, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 64, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO:57, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:65, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47.In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 57, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 66, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 59, LCDR2 comprises the amino acid sequence of SEQ ID NO: 67, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 59, LCDR2 comprises the amino acid sequence of SEQ ID NO: 68, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 52, LCDR2 comprises the amino acid sequence of SEQ ID NO: 46, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 53. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 57, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 59, LCDR2 comprises the amino acid sequence of SEQ ID NO: 69, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47.In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 57, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 59, LCDR2 comprises the amino acid sequence of SEQ ID NO: 70, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 71, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 72, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 73, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO:56, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:74, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47.In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 75, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 67, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 48, HCDR2 comprises the amino acid sequence of SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 68, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 54, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 76, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO:56, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:77, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47.In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 56, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 78, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 56, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 79, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 57, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 69, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO: 57, HCDR2 comprises the amino acid sequence of SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of SEQ ID NO: 44, LCDR1 comprises the amino acid sequence of SEQ ID NO: 45, LCDR2 comprises the amino acid sequence of SEQ ID NO: 80, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 47. In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO:57, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:70, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47.In some embodiments, in the antibodies or antigen-binding fragments provided herein, HCDR1 comprises the amino acid sequence of SEQ ID NO:54, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:81, and LCDR3 comprises the amino acid sequence of SEQ ID NO:47.

[0279] In some embodiments, the antibody further comprises one or more framework regions of SEQ ID NOs: 1 to 41. In some embodiments, the antibodies provided herein are humanized antibodies. The framework regions described herein are determined based on the boundaries of the CDR numbering system. In other words, if the CDRs are determined by, for example, Kabat, IMGT, or Chothia, the framework regions are the amino acid residues surrounding the CDRs in the variable region of the FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4 format from N-terminus to C-terminus. For example, FR1 is defined as the amino acid residue located N-terminal to the CDR1 amino acid residue as defined by, e.g., the Kabat numbering system, the IMGT numbering system, or the Chothia numbering system, FR2 is defined as the amino acid residue between the CDR1 amino acid residue and the CDR2 amino acid residue as defined by, e.g., the Kabat numbering system, the IMGT numbering system, or the Chothia numbering system, FR3 is defined as the amino acid residue between the CDR2 amino acid residue and the CDR3 amino acid residue as defined by, e.g., the Kabat numbering system, the IMGT numbering system, or the Chothia numbering system, and FR4 is defined as the amino acid residue located C-terminal to the CDR3 amino acid residue as defined by, e.g., the Kabat numbering system, the IMGT numbering system, or the Chothia numbering system.

[0280] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 1 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 3 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 4 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 5 and a VL comprising the amino acid sequence of SEQ ID NO: 6. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 6. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 8 and a VL comprising the amino acid sequence of SEQ ID NO: 6. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 9 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 10 and a VL comprising

[0281] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 13 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 14. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 15. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 16. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 17. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO:

[0282] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 19. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 20. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 21. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 22. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 23. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 24. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 6. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 25. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO:

[0283] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 27. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 28. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 29. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 30. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 31. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 32. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 33. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 9 and a VL comprising the amino acid sequence of SEQ ID NO: 34. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising

[0284] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 36. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 37. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 38. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 39. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 40. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH comprising the amino acid sequence of SEQ ID NO:9 and a VL comprising the amino acid sequence of SEQ ID NO:41.

[0285] In certain embodiments, the antibodies or antigen-binding fragments thereof described herein comprise an amino acid sequence having a certain percent identity relative to any of the antibodies provided herein (e.g., those described in Section 7, below).

[0286] The determination of percent identity between two sequences (e.g., amino acid sequences or nucleic acid sequences) can be accomplished using a mathematical algorithm. A non-limiting example of a mathematical algorithm for comparing two sequences is the algorithm of Karlin and Altschul, Proc. Natl. Acad. Sci. USA 87:2264-2268 (1990), as modified in Karlin and Altschul, Proc. Natl. Acad. Sci. USA 90:5873-5877 (1993). This algorithm is incorporated into the NBLAST and XBLAST programs of Altschul et al., J. Mol. Biol. 215:403 (1990). BLAST nucleotide searches can be performed with the NBLAST nucleotide program parameters set to, for example, score = 100 and word length = 12 to obtain nucleotide sequences homologous to the nucleic acid molecules described herein.

[0287] BLAST protein searches can be performed with the XBLAST program parameters set to, for example, score = 50 and wordlength = 3, to obtain amino acid sequences homologous to the protein molecules described herein. To obtain gapped alignments for comparison purposes, Gapped BLAST can be utilized as described in Altschul et al., Nucleic Acids Res. 25:3389-3402 (1997).

[0288] In some embodiments, the present invention provides the method for the comparison of the sequence of the two sequences of the present invention.For example, the method for the comparison of the sequence of the two sequences of the present invention can be used to determine the identity percentage between the two sequences. Alternatively, PSI BLAST can be used for iterative search, which detects the long-range relationship (Id.) between molecules. When utilizing BLAST, Breach BLAST and PSI Blast programs, the default parameters of the corresponding programs (for example, the default parameters of XBLAST and NBLAST) can be used (see for example, National Center for Biotechnology Information (NCBI), World Wide Web: ncbi.nlm.nih.gov). Another non-limiting example of the mathematical algorithm for sequence comparison is the algorithm of Myers and Miller, CABIOS 4:11-17 (1998). This algorithm is incorporated into the ALIGN program (version 2.0), which is a part for the GCG sequence alignment software package. When utilizing the ALIGN program to compare amino acid sequences, PAM 120 weight residue tables, gap length penalty 12 and gap penalty 4 can be used. The technology similar to those technologies described above can be used to determine the identity percentage between the two sequences when allowing or not allowing gaps. When calculating the identity percentage, typically only the exact matches are counted.

[0289] In some embodiments, the antibodies provided herein contain substitutions (e.g., conservative substitutions), insertions, or deletions relative to a reference sequence, but anti-ACVR2A antibodies comprising such sequences retain the ability to bind to ACVR2A. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted, and / or deleted in the reference amino acid sequence. In some embodiments, the substitutions, insertions, or deletions occur in regions outside of the CDRs (i.e., within the FRs). Optionally, the anti-ACVR2A antibodies provided herein include post-translational modifications of the reference sequence.

[0290] In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 1, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:3, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:4, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:5, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:6.In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:7, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:6. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:8, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:6. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:9, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 10, and a VL domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 2.In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 11, and a VL domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO:2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 12, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 13, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO:7, and a VL domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO:14.In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:7, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:15. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:7, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:2. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 12, and a VL domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 16. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:7, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:17.In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:7, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:18. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:7, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:19. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:7, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:20. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 12, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 21.In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 12, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 22. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:7, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:23. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO:7, and a VL domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO:24. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:7, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:6.In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 12, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 25. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 12, and a VL domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 26. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:7, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:27. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:7, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:28.In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:7, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:29. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 11, and a VL domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 30. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:7, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO:31. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO:7, and a VL domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO:32.In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO:7, and a VL domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO:33. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 9, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 11, and a VL domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 35. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 11, and a VL domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 36.In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 11, and a VL domain that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 37. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 12, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 38. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 12, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 39. In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 12, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 40.In some embodiments, the antibodies or antigen-binding fragments provided herein comprise a VH domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 9, and a VL domain that has at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 41. In all of the above embodiments, the antibody binds to ACVR2A.

[0291] In some embodiments, functional epitopes can be mapped, for example, by combined alanine scanning, to identify amino acids in the ACVR2A protein that are essential for interaction with the anti-ACVR2A antibodies provided herein. In some embodiments, the conformation and crystal structure of anti-ACVR2A antibodies bound to ACVR2A can be used to identify epitopes. In some embodiments, the present disclosure provides antibodies that specifically bind to the same epitope as any of the anti-ACVR2A antibodies provided herein. For example, in some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 1 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 3 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 4 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 5 and a VL comprising the amino acid sequence of SEQ ID NO: 6. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 6. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 8 and a VL comprising the amino acid sequence of SEQ ID NO: 6. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 9 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 10 and a VL comprising the amino acid sequence of SEQ ID NO: 2.In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 13 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 14. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 15. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 16. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 17. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 18. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 18.

[0292] An ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 19. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 20. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 21. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 22. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 23. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 23.

[0293] An ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 24. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 6. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 25. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 26. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 27. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 27.

[0294] An ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 28. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 29. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 30. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 31. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 32. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 32.

[0295] An ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 33. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 9 and a VL comprising the amino acid sequence of SEQ ID NO: 34. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 35. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 36. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 37. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 37.

[0296] An ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 38. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 39. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 40. In some embodiments, the antibodies or antigen-binding fragments provided herein bind to the same epitope as an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 9 and a VL comprising the amino acid sequence of SEQ ID NO: 41.

[0297] In some embodiments, provided herein are anti-ACVR2A antibodies or antigen-binding fragments thereof that compete with any of the anti-ACVR2A antibodies described herein for specific binding to ACVR2A. In some embodiments, provided herein are antibodies or antigen-binding fragments that compete with an anti-ACVR2A antibody for specific binding to ACVR2A, the anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 1 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, provided herein are antibodies or antigen-binding fragments that compete with an anti-ACVR2A antibody for specific binding to ACVR2A, the anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 3 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, provided herein are antibodies or antigen-binding fragments that compete with an anti-ACVR2A antibody for specific binding to ACVR2A.

[0298] ACVR2A, the anti-ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 4 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to ACVR2A, the anti-ACVR2A antibodies comprising a VH comprising the amino acid sequence of SEQ ID NO: 5 and a VL comprising the amino acid sequence of SEQ ID NO: 6. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to ACVR2A, the anti-ACVR2A antibodies comprising a VH comprising the amino acid sequence of SEQ ID NO: 5 and a VL comprising the amino acid sequence of SEQ ID NO: 6.

[0299] ACVR2A antibodies comprise a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 6. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to ACVR2A, the anti-ACVR2A antibodies comprising a VH comprising the amino acid sequence of SEQ ID NO: 8 and a VL comprising the amino acid sequence of SEQ ID NO: 6. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to ACVR2A, the anti-ACVR2A antibodies comprising a VH comprising the amino acid sequence of SEQ ID NO: 9 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to

[0300] ACVR2A, the anti-ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 10 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to ACVR2A, the anti-ACVR2A antibodies comprising a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to ACVR2A, the anti-ACVR2A antibodies comprising a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 2.

[0301] An ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 13 and a VL comprising the amino acid sequence of SEQ ID NO: 2 for specific binding to ACVR2A. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 14 for specific binding to ACVR2A.

[0302] ACVR2A, the anti-ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 15. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to ACVR2A, the anti-ACVR2A antibodies comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to ACVR2A, the anti-ACVR2A antibodies comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 2.

[0303] An ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 16. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with an anti-ACVR2A antibody for specific binding to ACVR2A, the anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 17. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with an anti-ACVR2A antibody for specific binding to ACVR2A, the anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 18. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with an anti-ACVR2A antibody for specific binding to ACVR2A.

[0304] ACVR2A, the anti-ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 19. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to ACVR2A, the anti-ACVR2A antibodies comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 20. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to ACVR2A, the anti-ACVR2A antibodies comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 20.

[0305] An ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 21. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 22 for specific binding to ACVR2A. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 23 for specific binding to ACVR2A. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with an anti-ACVR2A antibody for specific binding to ACVR2A.

[0306] ACVR2A, the anti-ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 24. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to ACVR2A, the anti-ACVR2A antibodies comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 6. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to ACVR2A, the anti-ACVR2A antibodies comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 6.

[0307] An ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 25. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 26 for specific binding to ACVR2A. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 27 for specific binding to ACVR2A.

[0308] ACVR2A, the anti-ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 28. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to ACVR2A, the anti-ACVR2A antibodies comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 29. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to ACVR2A, the anti-ACVR2A antibodies comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 29.

[0309] ACVR2A antibodies comprise a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 30. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with an anti-ACVR2A antibody for specific binding to ACVR2A, the anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 31. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with an anti-ACVR2A antibody for specific binding to ACVR2A, the anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 32. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with an anti-ACVR2A antibody for specific binding to

[0310] ACVR2A, the anti-ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 33. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to ACVR2A, the anti-ACVR2A antibodies comprising a VH comprising the amino acid sequence of SEQ ID NO: 9 and a VL comprising the amino acid sequence of SEQ ID NO: 34. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with anti-ACVR2A antibodies for specific binding to ACVR2A, the anti-ACVR2A antibodies comprising a VH comprising the amino acid sequence of SEQ ID NO: 9 and a VL comprising the amino acid sequence of SEQ ID NO: 34.

[0311] An ACVR2A antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 35. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with an anti-ACVR2A antibody for specific binding to ACVR2A, the anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 36. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with an anti-ACVR2A antibody for specific binding to ACVR2A, the anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 37. In some embodiments, the antibodies or antigen-binding fragments provided herein compete with an anti-ACVR2A antibody for specific binding to ACVR2A.

[0312] ACVR2A, the anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 38. In some embodiments, the antibodies or antigen-binding fragments provided herein compete for specific binding to ACVR2A with an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 39. In some embodiments, the antibodies or antigen-binding fragments provided herein compete for specific binding to ACVR2A with an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 40. In some embodiments, the antibodies or antigen-binding fragments provided herein compete for specific binding to ACVR2A with an anti-ACVR2A antibody comprising a VH comprising the amino acid sequence of SEQ ID NO: 9 and a VL comprising the amino acid sequence of SEQ ID NO: 41.

[0313] In some embodiments, provided herein are ACVR2A binding proteins comprising any of the anti-ACVR2A antibodies described above. In some embodiments, the ACVR2A binding protein is a monoclonal antibody, including a mouse antibody, a chimeric antibody, a humanized antibody, or a human antibody. In some embodiments, the anti-ACVR2A antibody is an antibody fragment (e.g., scFv). In some embodiments, the ACVR2A binding protein is a fusion protein comprising an anti-ACVR2A antibody provided herein. In other embodiments, the ACVR2A binding protein is a multispecific antibody comprising an anti-ACVR2A antibody provided herein. Other exemplary ACVR2A binding molecules are described in more detail in the following sections.

[0314] In some embodiments, an anti-ACVR2A antibody or antigen binding protein according to any of the above embodiments may incorporate any of the features, alone or in combination, as described in Sections 5.2.2 to 5.2.6 below.

[0315] 5.2.2. Antibody fragments

[0316] As used herein, the term "antibody" also includes various antibody fragments thereof. Antibodies provided herein include but are not limited to immunoglobulin molecules and immunologically active portions of immunoglobulin molecules. Immunoglobulin molecules provided herein can be any class (e.g., IgG, IgE, IgM, IgD and IgA) or any subclass (e.g., IgG1, IgG2, IgG3, IgG4, IgA1 and IgA2) of immunoglobulin molecules. In some embodiments, the antibody is an IgG antibody. In some embodiments, the IgG antibody is an IgG1 antibody. In some embodiments, the IgG antibody is an IgG2 antibody, an IgG3 antibody or an IgG4 antibody.

[0317] Variants and derivatives of antibodies include functional fragments of antibodies that retain the ability to bind to an antigen. Exemplary functional fragments include Fab fragments (e.g., antibody fragments containing an antigen binding domain and comprising a light chain and a portion of a heavy chain bridged by a disulfide bond); Fab' (e.g., an antibody fragment containing a single antigen binding domain comprising a Fab and an additional portion of a heavy chain via a hinge region); F(ab')2 (e.g., two Fab' molecules linked by an interchain disulfide bond in the hinge region of the heavy chain; the Fab' molecules can be directed against the same or different epitopes); bispecific Fab (e.g., a Fab molecule having two antigen binding domains, each of which can be directed against a different epitope); a single chain comprising a variable region, also known as scFv (e.g., the variable antigen binding determining regions of a single light chain and a heavy chain of an antibody linked together by a chain of, for example, 10 to 25 amino acids); disulfide-linked Fv or dsFv (e.g., the variable antigen binding determining regions of a single light chain and a heavy chain of an antibody linked together by disulfide bonds); camelized VH (e.g., the variable antigen binding determining regions of a single heavy chain of an antibody); region, in which some of the amino acids at the VH interface are those found in naturally occurring camelid antibody heavy chains); bispecific scFv (e.g., an scFv or dsFv molecule having two antigen-binding domains, wherein each antigen-binding domain can be directed against a different epitope); diabody (e.g., a dimeric scFv formed when the VH domain of a first scFv is assembled with the VL domain of a second scFv, and the VL domain of the first scFv is assembled with the VH domain of the second scFv; the two antigen-binding regions of the diabody can be directed against the same or different epitopes); triabody (e.g., a trimerized scFv, which is formed in a manner similar to a diabody, but in which three antigen-binding domains are generated in a single complex; the three antigen-binding domains can be directed against the same or different epitopes); and tetrabody (e.g., a tetrameric scFv, which is formed in a manner similar to a diabody, but in which four antigen-binding domains are generated in a single complex; the four antigen-binding domains can be directed against the same or different epitopes).

[0318] A variety of techniques have been developed to produce antibody fragments. Traditionally, these fragments are obtained by proteolytic digestion of intact antibodies (see, for example, Morimoto et al., 1992, J.Biochem.Biophys.Methods 24:107-17; and Brennan et al., 1985, Science 229:81-83). However, these fragments can now be produced directly by recombinant host cells. For example, Fab, Fv and scFv antibody fragments can all be expressed in and secreted from Escherichia coli (E.coli) or yeast cells, thus allowing for easy production of a large number of these fragments. Antibody fragments can be isolated from the above-mentioned antibody phage library. Alternatively, Fab'-SH fragments can be directly recovered from E. coli and chemically coupled to form F(ab')2 fragments (Carter et al., 1992, Bio / Technology 10:163-67). According to another method, F(ab')2 fragments can be directly isolated from recombinant host cell cultures. Fab and F(ab')2 fragments comprising salvage receptor binding epitope residues with increased in vivo half-life are described, for example, in U.S. Patent No. 5,869,046. Other techniques for producing antibody fragments will be apparent to those skilled in the art. In certain embodiments, the antibody is a single-chain Fv fragment (scFv) (see, for example, WO 93 / 16185; U.S. Patent Nos. 5,571,894 and 5,587,458). Fv and scFv have complete binding sites that lack constant regions; therefore, they may be suitable for reducing nonspecific binding during in vivo use. scFv fusion proteins can be constructed to produce fusions of effector proteins at the amino or carboxyl termini of scFv (see, for example, Borrebaeck et al., supra). Antibody fragments may also be "linear antibodies," for example, as described in the references cited above. Such linear antibodies may be monospecific or multispecific, such as bispecific.

[0319] 5.2.3. Antibody variants

[0320] In some embodiments, amino acid sequence modifications of the antibodies described herein that bind to ACVR2A are contemplated. For example, it may be desirable to optimize the binding affinity and / or other biological properties of the antibody, including but not limited to specificity, thermal stability, expression level, effector function, glycosylation, reduced immunogenicity, or solubility. Thus, in addition to the antibodies described herein that bind to ACVR2A, it is contemplated that variants of the antibodies described herein that bind to ACVR2A can be prepared. For example, antibody variants can be prepared by introducing appropriate nucleotide changes into the encoding DNA and / or by synthesizing the desired antibody or polypeptide. Those skilled in the art will appreciate that amino acid changes may alter post-translational processes of the antibody.

[0321] Chemical modification

[0322] In some embodiments, the antibody provided herein is chemically modified, for example, by the covalent attachment of any type of molecule to the antibody. Antibody derivatives can include chemically modified antibodies, which are for example chemically modified by glycosylation, acetylation, pegylation, phosphorylation, amidation, by derivatization of known protection / blocking groups, proteolytic cleavage, connection with cell ligands or other proteins, or by conjugation with one or more immunoglobulin domains (for example, a part for Fc or Fc). Any of many chemical modifications can be carried out by known techniques, and these techniques include but are not limited to the metabolic synthesis of specific chemical cleavage, acetylation, preparation, tunicamycin, etc. In addition, the antibody can contain one or more non-classical amino acids.

[0323] In some embodiments, the antibodies provided herein are altered to increase or decrease the extent to which the antibodies are glycosylated. Addition or deletion of glycosylation sites can be conveniently achieved by altering the amino acid sequence such that one or more glycosylation sites are created or removed.

[0324] When the antibody provided herein is fused to the Fc district, the carbohydrate connected thereto can be changed. The natural antibody produced by mammalian cells typically comprises the biantennary oligosaccharide of branching, which is usually connected to the Asn297 of the CH2 domain in the Fc district by N connection. See, for example, Wright et al., TIBTECH 15:26-32 (1997). Oligosaccharides can include various carbohydrates, for example mannose, N-acetylglucosamine (GlcNAc), galactose and sialic acid and the fucose connected to the GlcNAc in the " stem " of biantennary oligosaccharide structure. In some embodiments, the oligosaccharide in the binding molecule provided herein can be modified to produce variants with some improved characteristics.

[0325] In other embodiments, when the antibodies provided herein are fused to an Fc region, the antibody variants provided herein can have a carbohydrate structure lacking fucose that is attached to the Fc region (directly or indirectly). For example, the amount of fucose in such an antibody can be 1% to 80%, 1% to 65%, 5% to 65%, or 20% to 40%. The amount of fucose is determined by calculating the average amount of fucose at Asn 297 within the sugar chain relative to the sum of all sugar structures (e.g., complex, hybrid, and high mannose structures) attached to Asn 297, as measured by MALDI-TOF mass spectrometry, for example, as described in WO 2008 / 077546. Asn297 refers to the asparagine residue located at approximately position 297 (EU numbering of Fc region residues) in the Fc region; however, Asn297 may also be located about ±3 amino acids upstream or downstream of position 297, i.e., between position 294 and position 300, due to minor sequence variations in antibodies. Such fucosylation variants may have improved ADCC function. See, for example, U.S. Patent Publication Nos. US2003 / 0157108 and US

[0326] No. 2004 / 0093621. Examples of publications related to "defucosylated" or "fucose-deficient" antibody variants include: US 2003 / 0157108; WO 2000 / 61739; WO 2001 / 29246; US 2003 / 0115614; US

[0327] 2002 / 0164328; US2004 / 0093621; US2004 / 0132140; US2004 / 0110704; US2004 / 0110282; US2004 / 0109865; WO 2003 / 085119; WO 2003 / 084570; WO 2005 / 035586;WO

[0328] 2005 / 035778; WO2005 / 053742; WO2002 / 031140; Okazaki et al., J. Mol. Biol. 336: 1239-1249 (2004); Yamane-Ohnuki et al., Biotech. Bioeng. 87: 614 (2004). Examples of cell lines capable of producing defucosylated antibodies include Lee 13 CHO cells that lack protein fucosylation (Ripka et al., Arch. Biochem. Biophys. 249: 533-545 (1986); U.S. Patent Application No. US2003 / 0157108; and WO2004 / 056312), and knockout cell lines, such as α-1,6-fucosyltransferase gene FUT8 knockout CHO cells (see, e.g., Yamane-Ohnuki et al., Biotech. Bioeng. 87: 614 (2004); Kanda, Y. et al., Biotechnol. Bioeng., 94(4): 680-688 (2006); and WO2003 / 085107).

[0329] Binding molecules comprising antibodies provided herein are also provided with bisected oligosaccharides, for example, wherein the biantennary oligosaccharide attached to the Fc region is bisected by GlcNAc. Such variants may have reduced fucosylation and / or improved ADCC function. Examples of such variants are described in, for example, WO 2003 / 011878 (Jean-Mairet et al.); U.S. Patent No. 6,602,684 (Umana et al.); and US2005 / 0123546 (Umana et al.). Variants having at least one galactose residue in the oligosaccharide attached to the Fc region are also provided. Such variants may have improved CDC function. Such variants are described in, for example, WO 1997 / 30087; WO 1998 / 58964; and WO 1999 / 22764.

[0330] In a molecule comprising an antibody of the invention and an Fc region, one or more amino acid modifications can be introduced into the Fc region to generate an Fc region variant. The Fc region variant can comprise a human Fc region sequence (e.g., a human IgG1, IgG2, IgG3, or IgG4 Fc region) comprising an amino acid modification (e.g., substitution) at one or more amino acid positions.

[0331] In some embodiments, the present application contemplates variants having some, but not all, effector functions, making them desirable candidates for applications where the in vivo half-life of the binding molecule is important but certain effector functions (such as complement and ADCC) are unnecessary or deleterious. In vitro and / or in vivo cytotoxicity assays can be performed to confirm reduction / depletion of CDC and / or ADCC activity. For example, Fc receptor (FcR) binding assays can be performed to ensure that the binding molecule lacks FcγR binding (and therefore may lack ADCC activity), but retains FcRn binding ability. Non-limiting examples of in vitro assays for evaluating ADCC activity of a molecule of interest are described in U.S. Pat. Nos. 5,500,362 (see, e.g., Hellstrom, I. et al., Proc. Nat'l Acad. Sci. USA 83:7059-7063 (1986)) and Hellstrom, I et al., Proc. Nat'l Acad. Sci. USA 82:1499-1502 (1985); 5,821,337 (see, e.g., Bruggemann, M. et al., J. Exp. Med. 166:1351-1361 (1987)). Alternatively, non-radioactive assays can be used (see, e.g., ACTI for flow cytometry). TM Non-radioactive cytotoxicity assay

[0332] (Cell Technology, Inc. Mountain View, CA); and CytoTox Non-radioactive cytotoxicity assay (Promega, Madison, WI). Effector cells that can be used for such assays include peripheral blood mononuclear cells (PBMC) and natural killer (NK) cells. Alternatively or additionally, ADCC activity of the molecule of interest can be assessed in vivo, for example, in an animal model, such as that disclosed in Clynes et al., Proc. Nat'l Acad. Sci. USA 95:652-656 (1998). C1q binding assays can also be performed to confirm that the antibody cannot bind to C1q and therefore lacks CDC activity. See, for example, C1q and C3c binding ELISAs in WO 2006 / 029879 and WO 2005 / 100402. To assess complement activation, a CDC assay can be performed (see, e.g., Gazzano-Santoro et al., J. Immunol. Methods 202: 163 (1996); Cragg, MS et al., Blood 101: 1045-1052 (2003); and Cragg, MS and MJ Glennie, Blood 103: 2738-2743 (2004)). FcRn binding and in vivo clearance / half-life assays can also be performed using methods known in the art (see, e.g., Petkova, SB et al., Int'l. Immunol. 18(12): 1759-1769 (2006)).

[0333] Binding molecules with reduced effector function include those with substitutions of one or more of Fc region residues 238, 265, 269, 270, 297, 327, and 329 ( U.S. Pat. No. 6,737,056 ). Such Fc mutants include those with substitutions at two or more of amino acid positions 265, 269, 270, 297, and 327, including the so-called "DANA" Fc mutant in which residues 265 and 297 are substituted with alanine ( U.S. Pat. No. 7,332,581 ).

[0334] Certain variants with improved or decreased binding to FcRs have been described. (See, e.g., U.S. Patent No. 6,737,056; WO 2004 / 056312, and Shields et al., J. Biol. Chem. 9(2):6591-6604 (2001).)

[0335] In some embodiments, the variant comprises an Fc region with one or more amino acid substitutions that improve ADCC, e.g., substitutions at positions 298, 333, and / or 334 of the Fc region (EU numbering of residues). In some embodiments, alterations are made in the Fc region that result in altered (i.e., improved or reduced) Clq binding and / or complement-dependent cytotoxicity (CDC), e.g., as described in U.S. Pat. No. 6,194,551, WO 99 / 51642, and Idusogie et al., J. Immunol. 164:4178-4184 (2000).

[0336] Binding molecules with increased half-life and improved binding to the neonatal Fc receptor (FcRn), which is responsible for the transfer of maternal IgG to the fetus (Guyer et al., J. Immunol. 117:587 (1976) and Kim et al., J. Immunol. 24:249 (1994)) are described in US 2005 / 0014934 A1 (Hinton et al.). These molecules comprise an Fc region having one or more substitutions therein that improve binding of the Fc region to FcRn. Such Fc variants include those with substitutions at one or more of the following Fc region residues: 238, 256, 265, 272, 286, 303, 305, 307, 311, 312, 317, 340, 356, 360, 362, 376, 378, 380, 382, ​​413, 424, or 434, such as substitution of Fc region residue 434 ( U.S. Pat. No. 7,371,826 ). For other examples of Fc region variants, see also Duncan and Winter, Nature 322: 738-40 (1988); U.S. Pat. No. 5,648,260; U.S. Pat. No. 5,624,821; and WO 94 / 29351.

[0337] In some embodiments, it may be desirable to generate cysteine ​​engineered antibodies in which one or more residues of an antibody are substituted with cysteine ​​residues. In some embodiments, the substituted residues occur at accessible sites of the antibody. By replacing those residues with cysteine, reactive sulfhydryl groups are thereby localized at accessible sites of the antibody and can be used to conjugate the antibody to other moieties, such as drug moieties or linker-drug moieties, to produce immunoconjugates, as further described herein.

[0338] Substitution, deletion or insertion

[0339] The variation can be a substitution, deletion or insertion of one or more codons encoding an antibody or polypeptide that results in a change in the amino acid sequence compared to the original antibody or polypeptide. Interested sites for substitution mutagenesis include CDRs and FRs.

[0340] Amino acid substitution can be the result of replacing a kind of amino acid with another kind of amino acid with similar structure and / or chemical properties (such as leucine is replaced with serine, for example conservative amino acid substitution).Can use standard techniques well known to those skilled in the art in the nucleotide sequence of coding molecule provided herein to introduce sudden change, comprise for example site-directed mutagenesis and PCR-mediated mutagenesis that cause amino acid substitution.Insert or disappearance can be optionally in the scope of about 1 to 5 amino acid.In certain embodiments, replace, disappearance or insertion comprise and be less than 25 amino acid substitutions, less than 20 amino acid substitutions, less than 15 amino acid substitutions, less than 10 amino acid substitutions, less than 5 amino acid substitutions, less than 4 amino acid substitutions, less than 3 amino acid substitutions or less than 2 amino acid substitutions relative to original molecule.In a specific embodiment, replacement is the conservative amino acid substitution carried out at one or more predicted non-essential amino acid residues.Can determine the variation that is allowed by systematically carrying out amino acid insertion, disappearance or replacement in sequence and testing the activity shown by parent antibody of gained variant.

[0341] Amino acid sequence insertions include amino-terminal and / or carboxyl-terminal fusions ranging in length from one residue to polypeptides containing multiple residues, as well as intrasequence insertions of single or multiple amino acid residues. Examples of terminal insertions include antibodies with an N-terminal methionyl residue.

[0342] The antibody produced by conservative amino acid substitution is included in the present disclosure.In conservative amino acid substitution, amino acid residue is replaced by the amino acid residue with a side chain with similar charge.As mentioned above, the amino acid residue family with a side chain with similar charge has been defined in the art.These families include amino acid with basic side chain (for example, lysine, arginine, histidine), amino acid with acidic side chain (for example, aspartic acid, glutamic acid), amino acid with uncharged polar side chain (for example, glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine), amino acid with non-polar side chain (for example, alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), amino acid with β-branched side chain (for example, threonine, valine, isoleucine) and amino acid with aromatic side chain (for example, tyrosine, phenylalanine, tryptophan, histidine). Alternatively, mutations can be introduced randomly along all or part of the coded sequence, such as by saturation mutagenesis, and the biological activity of the resulting mutant can be screened to identify mutants that retain activity. After mutagenesis, the coded protein can be expressed, and the activity of the protein can be determined. Conservative substitutions (for example, in amino acid groups with similar properties and / or side chains) can be carried out to maintain this characteristic or not significantly change this characteristic. Exemplary substitutions are shown in Table 2 below.

[0343] Table 2: Amino acid substitutions

[0344]

[0345] Amino acids can be grouped according to the similarity of the properties of their side chains (see, e.g., Lehninger, Biochemistry 73-75 (2nd ed., 1975)): (1) nonpolar: Ala (A), Val (V), Leu (L), Ile (I), Pro (P), Phe (F), Trp (W), Met (M); (2) uncharged polar: Gly (G), Ser (S), Thr (T), Cys (C), Tyr (Y), Asn (N), Gln (Q); (3) acidic: Asp (D), Glu (E); and (4) basic: Lys (K), Arg (R), His (H). Alternatively, naturally occurring residues can be divided into groups based on common side chain properties: (1) hydrophobic: norleucine, Met, Ala, Val, Leu, Ile; (2) neutral hydrophilic: Cys, Ser, Thr, Asn, Gln; (3) acidic: Asp, Glu; (4) basic: His, Lys, Arg; (5) residues affecting chain orientation: Gly, Pro; and (6) aromatic: Trp, Tyr, Phe. For example, any cysteine ​​residue that is not involved in maintaining the correct conformation of the antibody can also be substituted, for example, with another amino acid (such as alanine or serine) to improve the oxidative stability of the molecule and prevent aberrant cross-linking. Non-conservative substitutions would require exchanging a member of one of these classes for another.

[0346] The substitution variants of one type relate to one or more hypervariable region residues that replace parental antibody (for example, humanization or people's antibody).Usually, the gained variant selected for further study will have modification (for example, improvement) relative to parental antibody in some biological properties (for example, the affinity of increase, the immunogenicity of reduction), and / or some biological properties of parental antibody will be substantially retained.Exemplary substitution variants are affinity-matured antibodies, which can be easily produced using affinity maturation techniques (such as, those described herein) based on phage display.In brief, one or more CDR residues are mutated, and variant antibodies are displayed on phage and screened for specific biological activity (for example binding affinity).

[0347] Changes (e.g., substitutions) can be made in the CDRs, for example to improve antibody affinity. Such changes can be made in CDR "hot spots" (i.e., residues encoded by codons that undergo mutations at high frequency during the somatic maturation process) (see, for example, Chowdhury, Methods Mol.Biol.207:179-196 (2008)) and / or SDRs (a-CDRs), wherein the binding affinity of the resulting variant antibody or its fragment is tested. For example, in Hoogenboom et al., Methods in Molecular Biology 178:1-37 (O'Brien et al., ed., Human Press, Totowa, NJ, (2001)), affinity maturation by construction and reselection from a secondary library has been described. In some embodiments of affinity maturation, diversity is introduced into the variable genes selected for maturation by any of a variety of methods (e.g., error-prone PCR, chain shuffling, or oligonucleotide-directed mutagenesis). A secondary library is then created. The library is then screened to identify any antibody variant with the desired affinity. Another method for introducing diversity involves a method for CDRs, in which several CDR residues (e.g., 4 to 6 residues at a time) are randomized. For example, using alanine scanning mutagenesis or modeling, CDR residues that participate in antigen binding can be specifically identified. A more detailed description of affinity maturation is provided in the following section.

[0348] In some embodiments, substitution, insertion or deletion may occur in one or more CDRs, as long as such changes do not substantially reduce the ability of the antibody to bind antigens. For example, conservative changes (e.g., conservative substitutions as provided herein) that do not substantially reduce binding affinity can be made in the CDRs. In some embodiments of the variant antibody sequences provided herein, each CDR is unchanged, or contains no more than one, two or three amino acid substitutions.

[0349] A useful method for identifying residues or regions of antibodies that can be targeted for mutagenesis is referred to as "alanine scanning mutagenesis," as described in Cunningham and Wells, Science, 244:1081-1085 (1989). In this method, a residue or a group of target residues (e.g., charged residues, such as Arg, Asp, His, Lys, and Glu) are identified and replaced with neutral or negatively charged amino acids (e.g., alanine or polyalanine) to determine whether the interaction of the antibody with the antigen is affected. Additional substitutions can be introduced at amino acid positions that demonstrate functional sensitivity to the initial substitution. Alternatively or additionally, the crystal structure of the antigen-antibody complex is used to identify the contact points between the antibody and the antigen. Such contact residues and adjacent residues can be targeted or removed as candidates for substitution. Variants can be screened to determine whether they contain desired properties.

[0350] Amino acid sequence insertions include amino-terminal and / or carboxyl-terminal fusions ranging in length from one residue to polypeptides containing one hundred or more residues, as well as intrasequence insertions of single or multiple amino acid residues. Examples of terminal insertions include antibodies with an N-terminal methionyl residue. Other insertion variants of the antibody molecule include fusion of the N-terminus or C-terminus of the antibody with an enzyme (e.g., for ADEPT) or a polypeptide that increases the serum half-life of the antibody.

[0351] Methods known in the art, such as oligonucleotide-mediated (site-directed) mutagenesis, alanine scanning, and PCR mutagenesis can be used to perform mutations. Site-directed mutagenesis (see, e.g., Carter, Biochem J. 237: 1-7 (1986); and Zoller et al., Nucl. Acids Res. 10: 6487-500 (1982)), cassette mutagenesis (see, e.g., Wells et al., Gene 34: 315-23 (1985)), or other known techniques can be performed on cloned DNA to generate antibody variant DNA.

[0352] 5.2.4. In vitro affinity maturation

[0353] In some embodiments, the antibody variants with improved characteristics (such as affinity, stability or expression level) compared with the parent antibody can be prepared by in vitro affinity maturation.The same as natural prototype, in vitro affinity maturation is based on the principle of mutation and selection.Antibody library is displayed on the surface of organism (for example, phage, bacterium, yeast or mammalian cell) or associates (for example, covalently or non-covalently) with its encoding mRNA or DNA.The affinity of displayed antibody selects to allow separation of organism or the complex of the genetic information carrying the encoding antibody.Use two or three rounds of mutation and selection of display method (such as phage display) to produce the antibody fragment with the affinity of low nanomolar scope usually.The antibody of affinity maturation can have nanomolar or even picomolar affinity to target antigen.

[0354] Phage display is a method widely used to display and select antibodies. Antibodies are displayed on the surface of Fd or M13 bacteriophage as fusions with bacteriophage capsid proteins. Selection involves exposure to antigens to allow phage-displayed antibodies to bind to their targets, a process known as "panning". Phages that bind to the antigen are recovered and used to infect bacteria to produce phage for further rounds of selection. For review, see, for example, Hoogenboom, Methods. Mol. Biol. 178: 1-37 (2002); and Bradbury and Marks, J. Immunol. Methods 290: 29-49 (2004).

[0355] In some embodiments, a mammalian display system may be used.

[0356] Diversity can also be introduced into the CDRs of the antibody library in a targeted manner or by random introduction. The former method includes sequentially targeting all CDRs of the antibody by high-level or low-level mutagenesis, or targeting isolated hot spots of somatic hypermutation (see, for example, Ho et al., J.Biol.Chem.280:607-17 (2005)) or residues suspected of affecting affinity based on experimental basis or structural reasons. Diversity can also be introduced by replacing naturally diverse regions through DNA shuffling or similar techniques (see, for example, Lu et al., J.Biol.Chem.278:43496-507 (2003); U.S. Patents 5,565,332 and 6,989,250). Alternative techniques targeting hypervariable loops extending into framework residues (see, e.g., Bond et al., J. Mol. Biol. 348: 699-709 (2005)) employ loop deletions and insertions in the CDRs or use hybridization-based diversification (see, e.g., U.S. Patent Publication No. 2004 / 0005709). Additional methods for generating diversity in the CDRs are disclosed, e.g., in U.S. Patent No. 7,985,840. Additional methods that can be used for generating antibody libraries and / or antibody affinity maturation are disclosed, e.g., in U.S. Patent Nos. 8,685,897 and 8,603,930 and U.S. Publications Nos. 2014 / 0170705, 2014 / 0094392, 2012 / 0028301, 2011 / 0183855, and 2009 / 0075378, each of which is incorporated herein by reference.

[0357] Screening of libraries can be accomplished by various techniques known in the art. For example, antibodies can be immobilized on a solid support, column, needle, or cellulose / poly(vinylidene fluoride) membrane / other filter, expressed on host cells attached to an adsorbent plate or used for cell sorting, or conjugated to biotin for capture with streptavidin-coated beads or used in any other method for panning display libraries.

[0358] For review of in vitro affinity maturation methods, see, eg, Hoogenboom, Nature Biotechnology 23: 1105-16 (2005); Quiroz and Sinclair, Revista Ingeneria Biomedia 4: 39-51 (2010); and references therein.

[0359] 5.2.5. Antibody Modification

[0360] Covalent modifications of antibodies are included within the scope of the present disclosure. Covalent modifications include reacting targeted amino acid residues of the antibody with an organic derivatizing agent that is reactive with selected side chains or the N-terminal or C-terminal residues of the antibody. Other modifications include deamidation of glutaminyl and asparaginyl residues to the corresponding glutamyl and aspartyl residues, respectively; hydroxylation of proline and lysine; phosphorylation of the hydroxyl groups of seryl or threonyl residues; methylation of the α-amino groups of lysine, arginine, and histidine side chains (see, e.g., Creighton, et al., 2001; Creighton ... Proteins: StructureandMolecularProperties 79-86 (1983)); acetylation of the N-terminal amine; and amidation of any C-terminal carboxyl group.

[0361] Other types of covalent modifications included within the scope of the present disclosure include altering the native glycosylation pattern of the antibody or polypeptide as described above (see, e.g., Beck et al., Curr. Pharm. Biotechnol. 9:482-501 (2008); and Walsh, Drug Discov. Today 15:773-80 (2010)), and linking the antibody to one of a variety of nonprotein polymers (e.g., polyethylene glycol (PEG), polypropylene glycol, or polyoxyalkylenes) in a manner such as described in U.S. Pat. Nos. 4,640,835; 4,496,689; 4,301,144; 4,670,417; 4,791,192; or 4,179,337. The disclosed antibodies that bind to ACVR2A can also be genetically fused or conjugated to one or more immunoglobulin constant regions or portions thereof (eg, Fc) to extend half-life and / or confer known Fc-mediated effector functions.

[0362] The disclosed antibodies that bind to ACVR2A can also be modified to form chimeric molecules comprising an antibody that binds to ACVR2A conjugated to another heterologous polypeptide or amino acid sequence (e.g., an epitope tag) (see, e.g., Terpe, Appl. Microbiol. Biotechnol. 60:523-33 (2003)) or the Fc region of an IgG molecule (see, e.g., Aruffo, AntibodyFusionProteins 221-42 (Chamow and Ashkenazi eds., 1999)) fusion.

[0363] Also provided herein are fusion proteins comprising an antibody of the present disclosure that binds to ACVR2A and a heterologous polypeptide. In some embodiments, a heterologous polypeptide genetically fused or chemically conjugated to an antibody can be used to target the antibody to cells that have ACVR2A expressed on the cell surface.

[0364] Also provided herein are panels of antibodies that bind to the ACVR2A antigen. In specific embodiments, the panel of antibodies has different on-rates, different off-rates, different affinities for the ACVR2A antigen, and / or different specificities for the ACVR2A antigen. In some embodiments, the panel comprises or consists of about 10 to about 1000 or more antibodies. The panel of antibodies can be used, for example, in 96-well or 384-well plates for assays such as ELISA.

[0365] 5.2.6. Other Binding Molecules Including Antibodies

[0366] In another aspect, provided herein are binding molecules comprising the anti-ACVR2A antibodies provided herein. In some embodiments, the antibodies to ACVR2A provided herein are part of other binding molecules. Exemplary binding molecules of the present disclosure are described herein.

[0367] Fusion protein

[0368] In various embodiments, the antibodies provided herein can be genetically fused or chemically conjugated to another agent (e.g., a protein-based entity). The antibody can be chemically conjugated to the agent, or otherwise non-covalently conjugated to the agent. The agent can be a peptide or an antibody (or a fragment thereof).

[0369] Thus, in some embodiments, provided herein are antibodies and uses thereof that are recombinantly fused or chemically conjugated (covalently or non-covalently) to a heterologous protein or polypeptide (or a fragment thereof, e.g., to about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, about 150, about 200, about 250, about 300, about 350, about 400, about 450, or about 500 amino acids or a polypeptide of more than 500 amino acids) to produce a fusion protein. In particular, provided herein are fusion proteins comprising an antigen-binding fragment (e.g., CDR1, CDR2, and / or CDR3) of an antibody provided herein and a heterologous protein, polypeptide, or peptide.

[0370] In addition, the antibodies provided herein can be fused to markers or "tag" sequences (such as peptides) to facilitate purification. In specific embodiments, the marker or tag amino acid sequence is a hexa-histidine peptide, hemagglutinin ("HA") tag, and a "FLAG" tag.

[0371] Methods for fusing or conjugating moieties, including polypeptides, to antibodies are known (see, e.g., Amon et al., Monoclonal Antibodies for Immunotargeting of Drugs in Cancer Therapy, in Monoclonal Antibodies and Cancer Therapy 243-56 (Reisfeld et al., eds., 1985); Hellstrom et al., Antibodies for Drug Delivery, in Controlled Drug Delivery 623-53 (Robinson et al., eds., 2nd ed., 1987); Thorpe, Antibody Carriers of Cytotoxic Agents in Cancer Therapy: A Review, in Monoclonal Antibodies: Biological and Clinical Applications 475-506 (Pinchera et al., eds., 1985); Analysis, Results, and Future Prospective of the Therapeutic Use of Radiolabeled Antibodies in Cancer Therapy, in Monoclonal Antibodies for Cancer Detection and Therapy 303-16 (Baldwin et al., eds., 1985); Thorpe et al., Immunol. Rev. 62:119-58 (1982); U.S. Patent Nos. 5,336,603; 5,622,929; 5,359,046; 5,349,053; 5,447,851; 5,723,125; 5,783,181; 5,908,626; 5,844,095; and 5,112,946; EP 307,434; EP 367,166; EP 394,827; PCT Publications WO 91 / 06570, WO 96 / 04388, WO 96 / 22024, WO 97 / 34631, and WO 99 / 04813; Ashkenazi et al., Proc. Natl. Acad. Sci. USA, 88:10535-39 (1991); Traunecker et al., Nature, 331:84-86 (1988); Zheng et al., J. Immunol.154:5590-600 (1995); and Vil et al., Proc. Natl. Acad. Sci. USA 89:11337-41 (1992).

[0372] Fusion proteins can be generated, for example, by gene shuffling, motif shuffling, exon shuffling, and / or codon shuffling (collectively referred to as "DNA shuffling") techniques. DNA shuffling can be used to alter the activity of antibodies as provided herein, including, for example, antibodies with higher affinity and lower off-rates (see, e.g., U.S. Patent Nos. 5,605,793; 5,811,238; 5,830,721; 5,834,252; and 5,837,458; Patten et al., Curr. Opinion Biotechnol. 8:724-33 (1997); Harayama, Trends Biotechnol. 16(2):76-82 (1998); Hansson et al., J. Mol. Biol. 287:265-76 (1999); and Lorenzo and Blasco, Biotechniques 24(2):308-13 (1998)). Antibodies or encoded antibodies can be altered by random mutagenesis by error-prone PCR, random nucleotide insertion, or other methods prior to recombination. The polynucleotides encoding the antibodies provided herein can be recombined with one or more components, motifs, segments, parts, domains, fragments, etc., of one or more heterologous molecules.

[0373] In some embodiments, an antibody provided herein is conjugated to a second antibody to form an antibody heteroconjugate.

[0374] In various embodiments, the antibody is genetically fused to the agent. Genetic fusion can be accomplished by placing a linker (e.g., a polypeptide) between the antibody and the agent. The linker can be a flexible linker.

[0375] In various embodiments, the antibody is genetically conjugated to a therapeutic molecule, wherein the hinge region connects the antibody to the therapeutic molecule.

[0376] Also provided herein are methods for preparing the various fusion proteins provided herein. The various methods described in Section 5.4 can also be used to prepare the fusion proteins provided herein.

[0377] In a specific embodiment, the fusion protein provided herein is recombinantly expressed. The recombinant expression of the fusion protein provided herein may require the construction of an expression vector containing the polynucleotide encoding this protein or its fragment. Once the polynucleotide encoding the protein provided herein or its fragment has been obtained, technology well known in the art can be used to produce the carrier for the production of this molecule by recombinant DNA technology. Therefore, this paper describes a method for preparing protein by expressing a polynucleotide containing a coding nucleotide sequence. Methods well known to those skilled in the art can be used to construct an expression vector containing a coding sequence and suitable transcription and translation control signals. These methods include, for example, in vitro recombinant DNA technology, synthetic technology, and in vivo gene recombination. A reproducible vector comprising a nucleotide sequence operably connected to a promoter is also provided, the fusion protein or its fragment or CDR provided by this nucleotide sequence encoding this paper being provided.

[0378] The expression vector can be transferred to a host cell by conventional techniques, and the transfected cells can then be cultured by conventional techniques to produce the fusion protein provided herein. Therefore, this paper also provides a host cell containing a polynucleotide operably linked to a heterologous promoter, the fusion protein or its fragment provided herein being encoded by this polynucleotide.

[0379] A variety of host expression vector systems can be used to express the fusion protein provided herein. Such host expression systems represent vehicles by which the coding sequence of interest can be produced and subsequently purified, and also represent cells that can in situ express the fusion protein provided herein when transformed or transfected with appropriate nucleotide coding sequences. These include, but are not limited to, microorganisms, such as bacteria (e.g., Escherichia coli and Bacillus subtilis (B. suhtilis)) transformed with recombinant bacterial phage DNA, plasmid DNA, or cosmid DNA expression vectors containing the coding sequence; yeast (e.g., Saccharomyces, Pichia) transformed with recombinant yeast expression vectors containing the coding sequence; insect cell systems infected with recombinant viral expression vectors (e.g., baculovirus) containing the coding sequence; insect cell systems infected with recombinant viral expression vectors (e.g., cauliflower mosaic virus, CaMV, tobacco mosaic virus, TMV) or with recombinant plasmid expression vectors containing the coding sequence. In some embodiments, the recombinant fusion protein can be expressed in a plant cell system transformed with a plasmid (e.g., a Ti plasmid); or a mammalian cell system (e.g., COS, CHO, BHK, 293, NSO, and 3T3 cells) with a recombinant expression construct containing a promoter derived from the mammalian cell genome (e.g., a metallothionein promoter) or a promoter derived from a mammalian virus (e.g., adenovirus late promoter; vaccinia virus 7.5K promoter). Bacterial cells (such as E. coli) or eukaryotic cells (particularly eukaryotic cells for expressing complete recombinant antibody molecules) can be used to express the recombinant fusion protein. For example, mammalian cells (such as Chinese hamster ovary cells (CHO)) combined with a vector (such as a major intermediate early gene promoter element from human cytomegalovirus) are effective expression systems for antibodies or their variants. In a specific embodiment, the expression of the nucleotide sequence encoding the fusion protein provided herein is regulated by a constitutive promoter, an inducible promoter, or a tissue-specific promoter.

[0380] In bacterial systems, many expression vectors can be advantageously selected depending on the intended use of the expressed fusion protein. For example, when a large amount of such fusion proteins are to be produced, in order to produce a pharmaceutical composition of the fusion protein, it may be desirable to instruct the expression of a high-level vector of a fusion protein product that is easily purified. Such vectors include, but are not limited to, the E. coli expression vector pUR278 (Ruther et al., EMBO 12: 1791 (1983)), in which the coding sequence can be linked to the vector alone in frame with the lac Z coding region to produce a fusion protein; pIN vectors (Inouye and Inouye, Nucleic Acids Res. 13: 3101-3109 (1985); Van Heeke and Schuster, J. Biol. Chem. 24: 5503-5509 (1989)); and the like. pGEX vectors can also be used to express exogenous polypeptides as fusion proteins with glutathione 5-transferase (GST). Generally speaking, such fusion proteins are soluble and can be easily purified from lysed cells by adsorption and binding to the matrix glutathione agarose beads, followed by elution in the presence of free glutathione. pGEX vectors are designed to include thrombin or factor Xa protease cleavage sites so that the cloned target gene product can be released from the GST moiety.

[0381] In mammalian host cells, many virus-based expression systems can be used. When adenovirus is used as an expression vector, the coding sequence of interest can be connected to the adenoviral transcription / translation control complex (e.g., late promoter and tripartite leader sequence). The chimeric gene can then be inserted into the adenoviral genome by in vitro or in vivo recombination. Insertion into the non-essential regions of the viral genome (e.g., region E1 or E3) will produce a recombinant virus that is alive and capable of expressing the fusion protein in the infected host (e.g., see Logan and Shenk, Proc. Natl. Acad. Sci. USA 8 1: 355-359 (1984)). Specific initiation signals may also be necessary for the effective translation of the inserted coding sequence. These signals include the ATG initiation codon and adjacent sequences. In addition, the initiation codon must be in phase with the reading frame of the desired coding sequence to ensure translation of the entire insert. These exogenous translation control signals and initiation codons can come from a variety of sources, both natural and synthetic. The efficiency of expression can be enhanced by including appropriate transcription enhancer elements, transcription terminators, etc. (see, eg, Bittner et al., Methods in Enzymol. 153:51-544 (1987)).

[0382] In addition, the expression of the inserted sequence can be selected or the host cell strain of modifying and processing gene product in a required ad hoc manner can be selected. Such modification (for example, glycosylation) and processing (for example, cutting) of protein product may be important for the function of protein. Different host cells have the characteristic and specific mechanism of post-translational processing and modification for protein and gene product. Suitable cell line or host system can be selected to guarantee the correct modification and processing of expressed foreign protein. For this reason, the eukaryotic host cell with the cellular mechanism of glycosylation and phosphorylation of suitable processing, gene product for primary transcript can be used. Such mammalian host cells include but are not limited to Chinese hamster ovary celI, VERY cell, BHK cell, Hela cell, COS cell, MDCK cell, 293 cell, 3T3 cell, W138 cell, BT483 cell, Hs578T cell, HTB2 cell, BT20 and T47D cell, NS0 cell (mouse myeloma cell line that does not endogenously produce any immunoglobulin chain), CRL7030 cell and HsS78Bst cell.

[0383] For the long-term, high-yield production of recombinant proteins, stable expression can be utilized.For example, the cell line of the through engineering approaches stably expressing fusion protein can be used. Instead of using the expression vector containing the viral replication origin, the host cell can be transformed with the DNA controlled by suitable expression control elements (for example, promoter, enhancer, sequence, transcription terminator, polyadenylation site etc.) and selective marker. After introducing foreign DNA, the engineered cells can be grown in enrichment medium for 1 to 2 days and then switched to the selective medium. The selective marker in the recombinant plasmid gives the resistance to selection, and allows the cell to stably integrate the plasmid into their chromosome and grow to form a focus, which can then be cloned and expanded into the cell line. The method can be advantageously used for the cell line of through engineering approaches expressing fusion protein. This type of engineered cell line can especially be used for screening and evaluating the interactional compositions directly or indirectly with binding molecules.

[0384] Many selection systems can be used, including but not limited to herpes simplex virus thymidine kinase (Wigler et al., Cell 11:223 (1977)), hypoxanthine guanine phosphoribosyltransferase (Szybalska and Szybalski, Proc. Natl. Acad. Sci. USA 48:202 (1992)), and adenine phosphoribosyltransferase (Lowy et al., Cell 22:8-17 (1980)) genes, which can be used for tk cells, hgprt cells, or aprt cells, respectively. In addition, antimetabolite resistance can be used as the basis for selection for the following genes: dhfr, which confers resistance to methotrexate (Wigler et al., Natl. Acad. Sci. USA 77:357 (1980); O'Hare et al., Proc. Natl. Acad. Sci. USA 78:1527 (1981));

[0385] gpt, which confers resistance to mycophenolic acid (Mulligan and Berg, Proc. Natl. Acad. Sci. USA 78:2072 (1981)); neo, which confers resistance to the aminoglycoside G-418 (Wu and Wu, Biotherapy 3:87-95 (1991); Tolstoshev, Ann. Rev. Pharmacol. Toxicol. 32:573-596 (1993); Mulligan, Science 260:926-932 (1993); and Morgan and Anderson, Ann. Rev. Biochem. 62:191-217 (1993); May, TIBTECH 11(5):155-215 (1993)); and hygro, which confers resistance to hygromycin (Santerre et al., Gene 30:147 (1984). Methods generally known in the art of recombinant DNA technology can be routinely applied to select the desired recombinant clones, and such methods are described, for example, in Ausubel et al. (eds.), CurrentProtocolsin MolecularBiology , John Wiley & Sons, NY (1993); Kriegler, Gene Transfer and Expression , A Laboratory Manual, Stockton Press, NY (1990); and Chapters 12 and 13, Dracopoli et al. (eds.), Current Protocols in Human Genetics, John Wiley & Sons, NY (1994); Colberre-Garapin et al., J. Mol. Biol. 150: 1 (1981), which are incorporated herein by reference in their entirety.

[0386] The expression level of the fusion protein can be increased by vector amplification (for review, see Bebbington and Hentschel, The use of vectors based on gene amplification for the expression of cloned genes in mammalian cells in DNA cloning, Volume 3 (Academic Press, New York, 1987)). When the marker in the vector system expressing the fusion protein is amplifiable, an increase in the level of inhibitors present in the host cell culture will increase the copy number of the marker gene. Since the amplified region is associated with the fusion protein gene, the production of the fusion protein will also increase (Crouse et al., Mol. Cell. Biol. 3:257 (1983)).

[0387] Can use the multiple expression vector co-transfection host cell that this paper provides.Carrier can contain identical selection marker, and it makes corresponding coded polypeptide can be equally expressed.Alternately, can use the single carrier that encodes and can express multiple polypeptide.Coding sequence can comprise cDNA or genomic DNA.

[0388] Once a fusion protein as provided herein has been produced by recombinant expression, the fusion protein can be purified by any method known in the art for purifying polypeptides (e.g., immunoglobulin molecules), for example, by chromatography (e.g., ion exchange chromatography, affinity chromatography (particularly by affinity for specific antigens after protein A), fractionated column chromatography, and kappa-selective affinity chromatography), centrifugation, differential solubility, or by any other standard technique for purifying proteins. In addition, the fusion protein molecules as provided herein can be fused to heterologous polypeptide sequences described herein or otherwise known in the art to facilitate purification.

[0389] Immunoconjugates

[0390] In some embodiments, the disclosure also provides immunoconjugates comprising any of the anti-ACVR2A antibodies described herein conjugated to one or more cytotoxic agents, such as chemotherapeutic agents or drugs, growth inhibitory agents, toxins (e.g., protein toxins, enzymatically active toxins of bacterial, fungal, plant, or animal origin, or fragments thereof), or radioactive isotopes.

[0391] In some embodiments, the immunoconjugate is an antibody-drug conjugate (ADC) in which the antibody is conjugated to one or more drugs, including but not limited to maytansinoid (see U.S. Pat. Nos. 5,208,020, 5,416,064 and European Patent EP 0 425 235). Bl); auristatin, such as the monomethyl auristatin drug moieties DE and DF (MMAE and MMAF) (see U.S. Pat. Nos. 5,635,483 and 5,780,588 and 7,498,298); dolastatin; calicheamicin or its derivatives (see U.S. Pat. Nos. 5,712,374, 5,714,586, 5,739,116, 5,767,285, 5,770,701, 5,770,710, 5,773,001, and 5,877,296; Hinman et al., Cancer Res. 53:3336-3342 (1993); and Lode et al., Cancer Res. 58:2925-2928 (1998)); anthracyclines such as daunorubicin or doxorubicin (see Kratz et al., Current Med. Chem. 13:477-523 (2006); Jeffrey et al., Bioorganic & Med. Chem. Letters 16:358-362 (2006); Torgov et al., Bioconj. Chem. 16:717-721 (2005); Nagy et al., Proc. Natl. Acad. Sci. USA 97:829-834 (2000); Dubowchik et al., Bioorg. & Med. Chem. Letters 12:1529-1532 (2002); King et al., J. Med. Chem. 45:4336-4343 (2002); and U.S. Pat. No. 6,630,579); methotrexate; vindesine; taxanes, such as docetaxel, paclitaxel, larotaxel, tesetaxel, and ortataxel; trichothecenes; and CC1065.

[0392] In some embodiments, the immunoconjugate comprises an antibody as described herein conjugated to an enzymatically active toxin or fragment thereof, including but not limited to diphtheria A chain, a nonbinding active fragment of diphtheria toxin, exotoxin A chain (from Pseudomonas aeruginosa), ricin A chain, abrin A chain, modeccin A chain, alpha-sarcin, Aleurites fordii proteins, dianthin proteins, Phytolaca americana proteins (PAPI, PAPII, and PAP-S), momordica charantia inhibitor, curcin, crotin, sapaonaria officinalis inhibitor, gelonin, mitogellin, restrictocin, phenomycin, enomycin, and trichothecenes.

[0393] In some embodiments, the immunoconjugate comprises an antibody as described herein conjugated to a radioactive atom to form a radioconjugate. A variety of radioactive isotopes can be used to produce radioconjugates. Examples include At 211 , I 131 , I 125 、Y 90 、Re 186 、Re 188 、Sm 153 、Bi 212 、P 32 , Pb 212 When the radioconjugate is used for detection, it may contain a radioactive atom such as tc99m or 1123 for scintigraphic studies, or a spin label such as iodine-123, iodine-131, indium-111, fluorine-19, carbon-13, nitrogen-15, oxygen-17, gadolinium, manganese or iron for nuclear magnetic resonance (NMR) imaging (also known as magnetic resonance imaging, mri).

[0394] Conjugates of the antibody and cytotoxic agent can be prepared using a variety of bifunctional protein coupling agents, such as N-succinimidyl-3-(2-pyridyldithio) propionate (SPDP), succinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate (SMCC), iminothiolane (IT), bifunctional derivatives of imidoesters (such as dimethyl diimidoadipate HCl), active esters (such as disuccinimidyl suberate), aldehydes (such as glutaraldehyde), bis-azido compounds (such as bis(p-azidobenzoyl)hexanediamine), bis-diazonium salt derivatives (such as bis-(p-diazoniumbenzoyl)-ethylenediamine), diisocyanates (such as toluene 2,6-diisocyanate), and bis-active fluorine compounds (such as 1,5-difluoro-2,4-dinitrobenzene). For example, ricin immunotoxins can be prepared as described in Vitetta et al., Science 238:1098 (1987). Carbon-14 labeled 1-isothiocyanatobenzyl-3-methyldiethylenetriaminepentaacetic acid (MX-DTPA) is an exemplary chelating agent for conjugating radionucleotides to antibodies. See WO 94 / 11026.

[0395] The linker can be a "cleavable linker" that facilitates release of the conjugated agent in the cell, but non-cleavable linkers are also encompassed herein. Linkers for use in the conjugates of the present disclosure include, but are not limited to, acid-labile linkers (e.g., hydrazone linkers), disulfide-containing linkers, peptidase-sensitive linkers (e.g., peptide linkers comprising amino acids such as valine and / or citrulline (such as citrulline-valine) or phenylalanine-lysine), photolabile linkers, dimethyl linkers, thioether linkers, or hydrophilic linkers designed to evade multidrug transporter-mediated resistance.

[0396] The immunoconjugates or ADCs herein encompass, but are not limited to, such conjugates prepared with cross-linker reagents including, but not limited to, BMPS, EMCS, GMBS, HBVS, LC-SMCC, MBS, MPBH, SBAP, SIA, SIAB, SMCC, SMPB, SMPH, sulfo-EMCS, sulfo-GMBS, sulfo-KMUS, sulfo-MBS, sulfo-SIAB, sulfo-SMCC, and sulfo-SMPB, and SVSB (succinimidyl-(4-vinylsulfone)benzoate), which are commercially available (e.g., from Pierce Biotechnology, Inc., Rockford, IL., USA).

[0397] In other embodiments, the antibodies provided herein are conjugated or recombinantly fused to, for example, diagnostic molecules. Such diagnosis and detection can be accomplished, for example, by coupling the antibody to a detectable substance, including, but not limited to, various enzymes such as, but not limited to, horseradish peroxidase, alkaline phosphatase, β-galactosidase, or acetylcholinesterase; prosthetic groups such as, but not limited to, streptavidin / biotin or avidin / biotin; fluorescent materials such as, but not limited to, umbelliferone, fluorescein, fluorescein isothiocyanate, rhodamine, dichlorotriazinylaminofluorescein, dansyl chloride, or phycoerythrin; luminescent materials such as, but not limited to, luminol; bioluminescent materials such as, but not limited to, luciferase, luciferin, or aequorin; chemiluminescent materials such as radioisotopes emitting 225Acγ, radioisotopes emitting Auger effects, radioisotopes emitting β rays, radioisotopes emitting α rays, or radioisotopes emitting positrons.

[0398] Polynucleotides

[0399] In certain embodiments, the present disclosure provides polynucleotides encoding antibodies of the present invention that bind to ACVR2A and fusion proteins comprising the antibodies described herein that bind to ACVR2A. The polynucleotides of the present disclosure can be in the form of RNA or in the form of DNA. DNA includes cDNA, genomic DNA, and synthetic DNA; and can be double-stranded or single-stranded, and if single-stranded, can be the coding strand or the non-coding (antisense) strand. In some embodiments, the polynucleotide is in the form of cDNA. In some embodiments, the polynucleotide is a synthetic polynucleotide.

[0400] The present disclosure also relates to variants of the polynucleotides described herein, wherein the variants encode, for example, fragments, analogs, and / or derivatives of the ACVR2A-binding antibodies of the present disclosure. In certain embodiments, the present disclosure provides polynucleotides comprising a polynucleotide having a nucleotide sequence that is at least about 75% identical, at least about 80% identical, at least about 85% identical, at least about 90% identical, at least about 95% identical, and in some embodiments, at least about 96%, 97%, 98%, or 99% identical to a polynucleotide encoding an ACVR2A-binding antibody of the present disclosure. As used herein, the phrase "a polynucleotide having a nucleotide sequence that is at least, for example, 95% "identical" to a reference nucleotide sequence" is intended to mean that the nucleotide sequence of the polynucleotide is identical to the reference sequence, except that the polynucleotide sequence may include up to five point mutations per 100 nucleotides of the reference nucleotide sequence. In other words, to obtain a polynucleotide having a nucleotide sequence that is at least 95% identical to a reference nucleotide sequence, up to 5% of the nucleotides in the reference sequence may be deleted or substituted with another nucleotide, or up to 5% of the total nucleotides in the reference sequence may be inserted into the reference sequence. These mutations of the reference sequence may occur at the 5' or 3' terminal positions of the reference nucleotide sequence or anywhere between these terminal positions, interspersed individually among nucleotides in the reference sequence or in one or more contiguous groups within the reference sequence.

[0401] Polynucleotide variants can contain changes in coding regions, noncoding regions or both. In some embodiments, polynucleotide variants contain changes that produce silent substitutions, additions or deletions but do not change the characteristics or activity of the encoded polypeptide. In some embodiments, polynucleotide variants comprise silent substitutions that cause the amino acid sequence of the polypeptide to not change (due to the degeneracy of the genetic code). Polynucleotide variants can be produced for a variety of reasons, for example, to optimize the codon expression of a specific host (that is, the codons in human mRNA are changed to codons preferred by bacterial hosts such as Escherichia coli. In some embodiments, polynucleotide variants comprise at least one silent mutation in the noncoding region or the coding region of the sequence.

[0402] In some embodiments, polynucleotide variants are produced to regulate or change the expression (or expression level) of the encoded polypeptide. In some embodiments, polynucleotide variants are produced to increase the expression of the encoded polypeptide. In some embodiments, polynucleotide variants are produced to reduce the expression of the encoded polypeptide. In some embodiments, the polynucleotide variants have increased expression of the encoded polypeptide compared to the parent polynucleotide sequence. In some embodiments, the polynucleotide variants have reduced expression of the encoded polypeptide compared to the parent polynucleotide sequence.

[0403] Also provided are vectors comprising the nucleic acid molecules described herein. In one embodiment, the nucleic acid molecules can be incorporated into recombinant expression vectors. The present disclosure provides recombinant expression vectors comprising any of the nucleic acids disclosed herein. As used herein, the term "recombinant expression vector" means a genetically modified oligonucleotide or polynucleotide construct that allows the mRNA, protein, polypeptide, or peptide to be expressed by a host cell when the construct comprises a nucleotide sequence encoding the mRNA, protein, polypeptide, or peptide and the vector is contacted with the cell under conditions sufficient to allow the mRNA, protein, polypeptide, or peptide to be expressed in the cell. The vectors described herein are not naturally occurring as a whole; however, portions of the vectors may be naturally occurring. The recombinant expression vectors described may comprise any type of nucleotides, including but not limited to DNA and RNA, which may be single-stranded or double-stranded, synthetic, or partially obtained from a natural source, and may contain natural nucleotides, non-natural nucleotides, or altered nucleotides. The recombinant expression vector may comprise naturally occurring internucleotide linkages or non-naturally occurring internucleotide linkages, or both types of linkages. Non-naturally occurring or altered nucleotides or internucleotide linkages do not hinder transcription or replication of the vector.

[0404] In one embodiment, the recombinant expression vector of the present disclosure can be any suitable recombinant expression vector, and can be used for transformation or transfection of any suitable host.Suitable vectors include vectors designed for propagation and amplification or designed for expression or both, such as plasmids and viruses.Carrier can be selected from the group consisting of: pUC series (Fermentas Life Sciences, Glen Burnie, Md.), pBluescript series (Stratagene, LaJolla, Calif.), pET series (Novagen, Madison, Wis.), pGEX series (Pharmacia Biotech, Uppsala, Sweden) and pEX series (Clontech, Palo Alto, Calif.). Bacteriophage vectors such as λ GT10, λ GT11, λ EMBL4 and λ NM1149, λ ZapII (Stratagene) can be used. The example of plant expression vector includes pBI01, pBI01.2, pBI121, pBI101.3 and pBIN19 (Clontech). Examples of animal expression vectors include pEUK-C1, pMAM, and pMAMneo (Clontech). The recombinant expression vector may be a viral vector, such as a retroviral vector, such as a gammaretroviral vector.

[0405] In one embodiment, recombinant expression vectors are prepared using standard recombinant DNA techniques as described in, for example, Sambrook et al. (supra) and Ausubel et al. (supra). Circular or linear expression vector constructs can be prepared to contain replication systems that function in prokaryotic or eukaryotic host cells. Replication systems can be derived from, for example, ColE1, SV40, 2μ plasmids, lambda, bovine papilloma virus, and the like.

[0406] Recombinant expression vectors may contain regulatory sequences, such as transcriptional and translational start and stop codons, that are specific for the type of host (e.g., bacteria, plants, fungi, or animals) into which the vector will be introduced, as appropriate and taking into account whether the vector is DNA-based or RNA-based.

[0407] The recombinant expression vector can include one or more marker genes that allow selection of the host for conversion or transfection. The marker gene includes biocide resistance (for example, resistance to antibiotics, heavy metals, etc.), the complementary effect of prototrophy provided in an auxotrophic host, etc. Suitable marker genes for described expression vectors include, for example, neomycin / G418 resistance gene, histidinol x resistance gene, histidinol resistance gene, tetracycline resistance gene, and ampicillin resistance gene.

[0408] The recombinant expression vector can comprise a natural or standard promoter operably connected to the nucleotide sequence of the present disclosure. The selection of promoters (e.g., strong promoters, weak promoters, tissue-specific promoters, inducible promoters and development-specific promoters) is within the ordinary skill of those skilled in the art. Similarly, the combination of nucleotide sequence and promoter is also within the technical scope of the technician. Promoter can be a non-viral promoter or a viral promoter, such as cytomegalovirus (CMV) promoter, RSV promoter, SV40 promoter or the promoter found in the long terminal repeat of mouse stem cell virus.

[0409] The recombinant expression vector can be designed for transient expression, for stable expression, or for both. In addition, the recombinant expression vector can be prepared for constitutive expression or inducible expression.

[0410] In addition, recombinant expression vectors can be prepared to include suicide genes. As used herein, the term "suicide gene" refers to a gene that causes cell death in which the suicide gene is expressed. A suicide gene can be a gene that confers sensitivity to a medicament (e.g., a drug) to cells expressing the gene, and causes cell death when the cells are contacted or exposed to the medicament. Suicide genes are known in the art and include, for example, herpes simplex virus (HSV) thymidine kinase (TK) genes, cytosine deaminase, purine nucleoside phosphorylase, and nitroreductase.

[0411] In certain embodiments, the polynucleotide is isolated.In certain embodiments, the polynucleotide is substantially pure.

[0412] Also provided are host cells comprising the nucleic acid molecules described herein. The host cell can be any cell containing a heterologous nucleic acid. The heterologous nucleic acid can be a vector (e.g., an expression vector). For example, the host cell can be a cell from any organism that is selected, modified, transformed, grown, used, or manipulated in any manner for producing a substance by the cell (e.g., expressing a gene, DNA or RNA sequence, protein, or enzyme by the cell). An appropriate host can be determined. For example, a host cell can be selected based on the vector backbone and the desired result. For example, a plasmid or cosmid can be introduced into a prokaryotic host cell to replicate several types of vectors. Bacterial cells (such as, but not limited to, DH5α, JM109, and KCB, Competent cells and SOLOP ACK Gold cells) can be used as host cells for vector replication and / or expression. In addition, bacterial cells (such as Escherichia coli LE392) can be used as host cells for phage viruses. The eukaryotic cells that can be used as host cells include but are not limited to yeast (for example, YPH499, YPH500 and YPH501), insects and mammals. The example of mammalian eukaryotic host cells for replication and / or expression of vectors includes but is not limited to HeLa, NIH3T3, Jurkat, 293, COS, Saos, PC12, SP2 / 0 (American Type Culture Collection (ATCC), Manassas, VA, CRL-1581), NSO (European Cell Culture Collection (ECACC), Salisbury, Wiltshire, UK, ECACC No. 85110503), FO (ATCC CRL-1646) and Ag653 (ATCC CRL-1580) mouse cell lines. An exemplary human myeloma cell line is U266 (ATCC CRL-TIB-196). Other useful cell lines include those derived from Chinese hamster ovary (CHO) cells, such as CHO-K1SV (Lonza Biologies, Walkersville, MD), CHO-K1 (ATCC CRL-61), or DG44.

[0413] 5.4. Antibody Preparation and Preparation Methods

[0414] Methods for preparing antibodies have been described. See, for example, Els Pardon et al., Nature Protocol, 9(3):674(2014). Antibodies (such as scFv fragments) can be obtained using methods known in the art, such as by immunizing camelid species (such as camels or llamas) and obtaining hybridomas therefrom, or by cloning antibody libraries using molecular biology techniques known in the art and subsequently selecting single clones from unselected libraries by ELISA or by using phage display.

[0415] The antibodies disclosed herein can be produced by culturing cells transformed or transfected with a vector containing a nucleic acid encoding the antibody. Standard recombinant techniques can be used to obtain polynucleotide sequences encoding the polypeptide components of the antibodies disclosed herein. The desired polynucleotide sequences can be isolated from antibody-producing cells, such as hybridoma cells or B cells, and sequenced. Alternatively, polynucleotides can be synthesized using a nucleotide synthesizer or PCR techniques. Once obtained, the sequence encoding the polypeptide is inserted into a recombinant vector capable of replicating and expressing the heterologous polynucleotide in a host cell. Many vectors available and known in the art can be used for the purposes of the present disclosure. The selection of an appropriate vector will depend primarily on the size of the nucleic acid to be inserted into the vector and the specific host cell to be transformed with the vector. Host cells suitable for expressing the antibodies disclosed herein include prokaryotes, such as archaea and eubacteria, including Gram-negative or Gram-positive organisms; eukaryotic microorganisms, such as filamentous fungi or yeast; invertebrate cells, such as insect or plant cells; and vertebrate cells, such as mammalian host cell lines. Host cells are transformed with the expression vectors described above and cultured in conventional nutrient media that are modified as appropriate to induce promoters, select transformants, or amplify genes encoding the desired sequences. Antibodies produced by the host cells are purified using standard protein purification methods known in the art.

[0416] Methods for antibody production, including vector construction, expression, and purification, are further described in Plückthun et al. Antibody Engineering:Producing antibodies in Escherichia coli:From PCR to fermentation 203-52 (McCafferty et al., eds., 1996); Kwong and Rader, E. coli Expression and Purification of Fab Antibody Fragments, eds. Current Protocols in Protein Science (2009); Tachibana and Takekoshi, Production of Antibody Fab Fragments in Escherichia coli AntibodyExpression and Production(Al-Rubeai ed., 2011); and Therapeutic MonoclonalAntibodies: FromBench toClinic (An ed., 2009).

[0417] Of course, it is contemplated that alternative methods well known in the art may be used to prepare anti-ACVR2A antibodies. For example, the appropriate amino acid sequence, or portion thereof, may be generated by direct peptide synthesis using solid phase techniques (see, e.g., Stewart et al., Solid-Phase Peptide Synthesis (1969); and Merrifield, J. Am. Chem. Soc. 85:2149-54 (1963). In vitro protein synthesis can be performed using manual techniques or by automation. The various parts of the anti-ACVR2A antibody can be chemically synthesized separately and combined using chemical or enzymatic methods to produce the desired anti-ACVR2A antibody. Alternatively, the antibody can be purified from cells or body fluids (such as milk) of transgenic animals engineered to express the antibody, as disclosed, for example, in U.S. Pat. Nos. 5,545,807 and 5,827,690.

[0418] polyclonal antibodies

[0419] Polyclonal antibodies are usually raised in animals by multiple subcutaneous (sc) or intraperitoneal (ip) injections of the relevant antigen and an adjuvant. Bifunctional or derivatizing agents such as maleimidobenzoyl sulfosuccinimide ester (conjugated through cysteine ​​residues), N-hydroxysuccinimide (conjugated through lysine residues), glutaraldehyde, succinic anhydride, SOCl2 or R 1 N=C=NR (where R and R 1 is independently a lower alkyl), it may be useful to conjugate the relevant antigen to a protein that is immunogenic in the species to be immunized (e.g., keyhole limpet hemocyanin (KLH), serum albumin, bovine thyroglobulin, or soybean trypsin inhibitor. Examples of adjuvants that can be used include Freund's complete adjuvant and MPL-TDM adjuvant (monophosphoryl lipid A, synthetic trehalose dicorynomycolate). The immunization protocol can be selected by those skilled in the art without undue experimentation.

[0420] For example, by combining, for example, 100 μg or 5 μg of protein or conjugate (for rabbits or mice, respectively) with 3 volumes of Freund's complete adjuvant and injecting the solution intradermally at multiple sites to immunize the animal against the antigen, immunogenic conjugate or derivative. One month later, the animal is boosted with 1 / 5 to 1 / 10 the original amount of peptide or conjugate in Freund's complete adjuvant by subcutaneous injection at multiple sites. After 7 to 14 days, the animal is bled and the antibody titer of the serum is determined. The animal is boosted until the titer reaches a stable level. The conjugate can also be prepared in recombinant cell culture as a protein fusion. Aggregating agents such as alum are also suitable for enhancing the immune response.

[0421] Monoclonal antibodies

[0422] A monoclonal antibody is obtained from a substantially homogeneous population of antibodies, i.e., the individual antibodies comprising the population are identical except for possible naturally occurring mutations and / or post-translational modifications (e.g., isomerization, amidation) that may be present in minor amounts. Thus, the modifier "monoclonal" indicates the character of the antibody as not being a mixture of discrete antibodies.

[0423] For example, monoclonal antibodies can be made using the hybridoma method first described by Kohler et al., Nature, 256:495 (1975), or can be made by recombinant DNA methods (US Pat. No. 4,816,567).

[0424] In another embodiment, antibodies can be isolated from antibody phage libraries generated using the techniques described in McCafferty et al., Nature, 348:552-554 (1990); Clackson et al., Nature, 352:624-628 (1991) and Marks et al., J. Mol. Biol., 222:581-597 (1991). Subsequent publications describe the generation of high-affinity (nM range) human antibodies by chain shuffling (Marks et al., Bio / Technology, 10:779-783 (1992)), and combinatorial infection and in vivo recombination as strategies for constructing very large phage libraries (Waterhouse et al., Nucl. Acids Res., 21:2265-2266 (1993)). Therefore, these techniques are viable alternatives to traditional monoclonal antibody hybridoma techniques for isolating monoclonal antibodies.

[0425] The DNA can also be modified, for example, by replacing the coding sequence (U.S. Patent No. 4,816,567; Morrison et al., Proc. Natl Acad. Sci. USA, 81:6851 (1984)) or by covalently linking to the coding sequence all or part of the coding sequence for a non-immunoglobulin polypeptide. Such non-immunoglobulin polypeptides can be substituted to create a chimeric bivalent antibody comprising one antigen-binding site specific for one antigen and another antigen-binding site specific for a different antigen.

[0426] Chimeric or hybrid antibodies can also be prepared in vitro using known methods in synthetic protein chemistry (including those involving cross-linking agents). For example, immunotoxins can be constructed using disulfide exchange reactions or by forming thioether bonds. Examples of suitable reagents for this purpose include iminothiolate and methyl-4-mercaptobutyrimidate.

[0427] Recombinant production in prokaryotes

[0428] The polynucleotide sequences encoding the antibodies of the present disclosure can be obtained using standard recombinant techniques. The desired polynucleotide sequences can be isolated and sequenced from cells producing the antibodies, such as hybridoma cells. Alternatively, polynucleotides can be synthesized using a nucleotide synthesizer or PCR technology. Once obtained, the sequence encoding the polypeptide is inserted into a recombinant vector capable of replicating and expressing heterologous polynucleotides in a prokaryotic host. Many vectors available and known in the art can be used for the purposes of the present disclosure. The selection of appropriate vectors will depend primarily on the size of the nucleic acid to be inserted into the vector and the specific host cell to be transformed with the vector. Each vector contains various components, which depends on its function (amplification or expression of heterologous polynucleotides, or both) and its compatibility with the specific host cell in which it resides. Vector components typically include, but are not limited to, an origin of replication, a selectable marker gene, a promoter, a ribosome binding site (RBS), a signal sequence, a heterologous nucleic acid insert, and a transcription termination sequence.

[0429] Generally speaking, plasmid vectors containing replicons and control sequences derived from species compatible with the host cells are used in conjunction with these hosts. Vectors typically carry replication sites and marker sequences that can provide phenotypic selection in transformed cells. For example, plasmid pBR322 derived from an E. coli species is typically used to transform E. coli. Examples of pBR322 derivatives for expressing specific antibodies are described in detail in Carter et al., U.S. Patent No. 5,648,237.

[0430] In addition, phage vectors containing replicons and control sequences compatible with the host microorganisms can be used as transformation vectors relevant to these hosts. For example, bacteriophages such as GEM TM -11 can be used to prepare recombinant vectors, which can be used to transform susceptible host cells such as Escherichia coli LE392.

[0431] The expression vector of the present application can comprise two or more promoter-cistron pairs, and its encoding every kind of polypeptide component.Promoter is the non-translated regulatory sequence that is positioned at the cistron upstream (5 ') that regulates its expression.Prokaryotic promoters are typically divided into two categories, inducible and constitutive.Inducible promoter is the promoter that starts the cistron transcription of increasing level under its control in response to the variation (for example, the existence or absence of nutrients or the variation of temperature) of culture condition.

[0432] In some embodiments, the promoter of the present invention can be used to express the target gene of the present invention.In ...

[0433] Promoters suitable for use with prokaryotic hosts include the PhoA promoter, the β-galactosidase and lactose promoter systems, the tryptophan (trp) promoter system, and hybrid promoters such as the tac or trc promoters. However, other promoters that function in bacteria (such as other known bacterial or phage promoters) are also suitable. Their nucleic acid sequences have been published so that one skilled in the art can operably link them to the cistron encoding the target peptide using linkers or adapters providing any desired restriction sites (Siebenlist et al., Cell 20:269 (1980)).

[0434] In one aspect, each cistron in the recombinant vector comprises a secretion signal sequence component, which instructs the expressed polypeptide to be transported across the membrane. Generally speaking, the signal sequence can be a component of the vector, or it can be a part of the target polypeptide DNA inserted into the vector. The signal sequence selected for the purposes of the present invention should be a signal sequence recognized and processed (i.e., cut by a signal peptidase) by the host cell. For prokaryotic host cells that do not recognize and process the natural signal sequence of heterologous polypeptides, the signal sequence can be replaced by the prokaryotic signal sequence selected from the group consisting of, for example, alkaline phosphatase, penicillinase, Ipp or heat-stable enterotoxin II (STII) leaders, LamB, PhoE, PelB, OmpA and MBP.

[0435] In some embodiments, production of antibodies according to the present disclosure can occur in the cytoplasm of the host cell, thus eliminating the need for a secretion signal sequence to be present within each cistron. - strains) provide cytoplasmic conditions that are favorable for disulfide bond formation, thereby allowing the correct folding and assembly of the expressed protein subunits.

[0436] Prokaryotic host cells suitable for expressing antibodies of the present disclosure include archaebacteria and eubacteria, such as gram-negative organisms or gram-positive organisms. The example of useful bacteria includes Escherichia (Escherichia) (for example, Escherichia coli), Bacillus (Bacilli) (for example, Bacillus subtilis), Enterobacteria (Enterobacteria), Pseudomonas (Pseudomonas) species (for example, Pseudomonas aeruginosa (P.aeruginosa)), Salmonella typhimurium (Salmonella typhimurium), Serratia marcescans (Serratia marcescans), Klebsiella (Klebsiella), Proteus (Proteus), Shigella (Shigella), Rhizobium (Rhizobia), Vitreoscilla (Vitreoscilla) or Paracoccus (Paracoccus). In some embodiments, gram-negative cells are used. In one embodiment, Escherichia coli cells are used as hosts. Examples of E. coli strains include strain W3110 (Bachmann, Cellular and Molecular Biology, Vol. 2 (Washington, DC: American Society for Microbiology, 1987), pp. 1190-1219; ATCC Accession No. 27,325) and derivatives thereof (including strains having the genotype W3110 AfhuA(AtonA)ptr3 lac Iq lacL8 AompT A(nmpc-fepE)degP41 kan R coli RV308 (ATCC 31,608). These examples are illustrative and not restrictive. Methods for constructing derivatives of any of the above bacteria having a defined genotype are known in the art and are described, for example, in Bass et al., Proteins, 8:309-314 (1990). It is generally necessary to consider the ability of the replicon to replicate in the bacterial cell to select an appropriate bacterium. For example, when well-known plasmids such as pBR322, pBR325, pACYC177, or pKN410 are used to provide the replicon, E. coli, Serratia, or Salmonella species can be suitably used as hosts.

[0437] Typically, the host cells should secrete minimal amounts of proteolytic enzymes, and it may be desirable to incorporate additional protease inhibitors into the cell culture.

[0438] Host cells are transformed with the expression vectors described above and cultivated in conventional nutrient media, which may be modified to induce promoters, select transformants or amplify genes encoding the desired sequence as appropriate. Conversion means introducing DNA into a prokaryotic host so that the DNA can be replicated as an extrachromosomal element or by a chromosomal integrant. Depending on the host cell used, standard techniques suitable for such cells are used for conversion. Calcium treatment is typically used for bacterial cells containing a large amount of cell wall barriers using calcium chloride. Another method for conversion employs polyethylene glycol / DMSO. Another technique employed is electroporation.

[0439] Prokaryotic cells for producing the antibodies of the present application are grown in culture media known in the art and suitable for culturing selected host cells. Examples of suitable culture media include Luria broth (LB) plus necessary nutritional supplements. In some embodiments, the culture media also contains a selection agent selected based on the construction of the expression vector to selectively allow the growth of prokaryotic cells containing the expression vector. For example, ampicillin is added to the culture media to grow cells expressing an ampicillin resistance gene.

[0440] In addition to carbon, nitrogen and inorganic phosphate sources, any necessary supplements may also be included, introduced separately or as a mixture with another supplement or medium (such as a complex nitrogen source) at appropriate concentrations. Optionally, the culture medium may contain one or more reducing agents selected from the group consisting of glutathione, cysteine, cystamine, thioglycollate, dithioerythritol and dithiothreitol. Prokaryotic host cells are cultivated at a suitable temperature and pH.

[0441] If an inducible promoter is used in the expression vector of the present application, protein expression is induced under conditions suitable for promoter activation. In one aspect of the present application, the PhoA promoter is used to control transcription of the polypeptide. Therefore, the transformed host cells are cultured in a phosphate-limited medium for induction. Preferably, the phosphate-limited medium is CRAP medium (see, for example, Simmons et al., J. Immunol. Methods 263: 133-147 (2002)). Depending on the vector construct used, a variety of other inducers can be used, as known in the art.

[0442] The expressed antibodies of the present disclosure are secreted into the periplasm of the host cell and recovered therefrom. Protein recovery typically involves destroying microorganisms, usually by modes such as osmotic shock, ultrasonic treatment or cracking. Once the cells are destroyed, cell debris or whole cells can be removed by centrifugation or filtration. The protein can be further purified, for example, by affinity resin chromatography. Alternatively, the protein can be transported to the culture medium and separated therein. Cells can be removed from the culture, and the culture supernatant can be filtered and concentrated to further purify the protein produced. The expressed polypeptide can be further separated and identified using commonly known methods (such as polyacrylamide gel electrophoresis (PAGE) and Western blotting assays).

[0443] Alternatively, protein production is performed in large quantities by a fermentation process. Various large-scale fed-batch fermentation procedures can be used to produce recombinant proteins. In order to improve the yield and quality of the disclosed antibodies, various fermentation conditions can be modified. For example, chaperone proteins have been shown to promote the correct folding and solubility of heterologous proteins produced in bacterial host cells. Chen et al., J Bio Chem 274: 19601-19605 (1999); U.S. Patent No. 6,083,715; U.S. Patent No. 6,027,888; Bothmann and Pluckthun, J. Biol. Chem. 275: 17100-17105 (2000); Ramm and Pluckthun, J. Biol. Chem. 275: 17106-17113 (2000); Arie et al., Mol. Microbiol. 39: 199-210 (2001).

[0444] To minimize proteolysis of the expressed heterologous proteins (especially those that are sensitive to proteolysis), certain host strains lacking proteolytic enzymes can be used in the present invention, as described, for example, in U.S. Pat. No. 5,264,365; U.S. Pat. No. 5,508,192; Hara et al., Microbial Drug Resistance, 2: 63-72 (1996). E. coli strains lacking proteolytic enzymes and transformed with plasmids that overexpress one or more chaperone proteins can be used as host cells in expression systems encoding the antibodies of the present application.

[0445] The antibodies produced herein can be further purified to obtain substantially homogeneous preparations for further determination and use. Standard protein purification methods known in the art can be adopted. The following procedures are examples of suitable purification procedures: fractionation on an immunoaffinity column or ion exchange column, ethanol precipitation, reversed-phase HPLC, chromatography on silica or on a cation exchange resin such as DEAE, chromatofocusing, SDS-PAGE, ammonium sulfate precipitation, and gel filtration using, for example, Sephadex G-75. For example, protein A immobilized on a solid phase can be used in some embodiments of immunoaffinity purification of binding molecules of the present disclosure. The solid phase for immobilizing protein A is preferably a column comprising a glass or silica surface, more preferably a controlled pore glass column or a silicic acid column. In some embodiments, the column has been coated with a reagent (such as glycerol) to attempt to prevent nonspecific adhesion of pollutants. The solid phase is then washed to remove the pollutants that are nonspecifically bound to the solid phase. Finally, the antibody of interest is recovered from the solid phase by elution.

[0446] Recombinant production in eukaryotic cells

[0447] For eukaryotic expression, vector components generally include, but are not limited to, one or more of the following: a signal sequence, an origin of replication, one or more marker genes and enhancer elements, a promoter, and a transcription termination sequence.

[0448] The vector for eukaryotic hosts can also comprise an insert of other polypeptides encoding a signal sequence or having a specific cleavage site at the N-terminal end of a mature protein or polypeptide. The heterologous signal sequence preferably selected is a sequence recognized and processed (that is, cut by a signal peptidase) by the host cell. In mammalian cell expression, mammalian signal sequences and viral secretion leader sequences, for example herpes simplex gD signal, can be obtained. The DNA in this precursor region can be connected to the DNA encoding the application's antibody in frame.

[0449] Generally, an origin of replication component is not required for mammalian expression vectors (the SV40 origin is typically used simply because it contains the early promoter).

[0450] Expression and cloning vectors can contain selection genes, also known as selectable markers. The selection gene can encode a protein that confers resistance to antibiotics or other toxins (e.g., ampicillin, neomycin, methotrexate, or tetracycline); complements nutritional deficiencies; or supplies key nutrients that are not available from complex media.

[0451] One example of a selection scheme utilizes drugs to prevent the growth of host cells. Those cells that are successfully transformed with a heterologous gene produce a protein that confers drug resistance and therefore survive the selection scheme. Examples of this type of dominant selection use the drugs neomycin, mycophenolic acid, and hygromycin.

[0452] Another example of a suitable selective marker for mammalian cells is the selective markers of cells that can identify the nucleic acids that can be taken up encoding the application's antibodies. For example, first, all transformants are identified by cultivating all transformants in a culture medium containing methotrexate (Mtx), a competitive antagonist of DHFR, to transform cells transformed with the DHFR selection gene. When adopting wild-type DHFR, an exemplary suitable host cell is the Chinese hamster ovary (CHO) cell line of DHFR activity defect. Alternatively, a host cell (particularly a wild-type host containing endogenous DHFR) transformed or cotransformed with a DNA sequence encoding a polypeptide, a wild-type DHFR protein, and another selective marker such as aminoglycoside 3'-phosphotransferase (APH) can be selected by growing the cell in a culture medium containing a selection agent (such as an aminoglycoside antibiotic) for the selective marker.

[0453] Expression vector and cloning vector contain the promoter that is recognized by host organism and is operably connected with the nucleic acid of coding required polypeptide sequence usually.Eukaryotic gene has the zone that is rich in AT, and it is positioned at about 25 to 30 bases in the site upstream of initial transcription.Can be included in another sequence that many gene transcription starts 70 to 80 bases upstream and finds.The 3 ' end of most eukaryotic organisms can be the signal that poly A tail is added to the 3 ' end of coding sequence.All these sequences can be inserted in the eukaryotic expression vector.

[0454] Transcription of the polypeptide from the vector in a mammalian host cell can be controlled, for example, by promoters obtained from the genome of viruses such as polyoma virus, fowlpox virus, adenovirus (such as adenovirus 2), bovine papilloma virus, avian sarcoma virus, cytomegalovirus, retroviruses, hepatitis B virus, and simian virus 40 (SV40), from heterologous mammalian promoters (e.g., the actin promoter or an immunoglobulin promoter), from heat shock promoters, provided that such promoters are compatible with the host cell systems.

[0455] Transcription of the DNA encoding the disclosed antibodies by higher eukaryotes is typically increased by inserting an enhancer sequence into the vector. Many enhancer sequences from mammalian genes (globin, elastase, albumin, α-fetoprotein, and insulin) are now known. Examples include the SV40 enhancer (bp 100-270), the cytomegalovirus early promoter enhancer, the polyoma enhancer, and the adenovirus enhancer on the late side of the replication origin. For enhancing elements for activating eukaryotic promoters, see also Yaniv, Nature 297:17-18 (1982). The enhancer can be spliced ​​into the vector at the 5' or 3' position of the polypeptide coding sequence, but is preferably located at the 5' position of the promoter.

[0456] Expression vectors for eukaryotic host cells (yeast, fungi, insects, plants, animals, humans, or nucleated cells from other multicellular organisms) also contain sequences necessary for terminating transcription and for stabilizing the mRNA. Such sequences are commonly obtained from the 5' and occasionally 3' untranslated regions of eukaryotic or viral DNA or cDNA. These regions contain nucleotide segments that are transcribed as polyadenylated fragments in the untranslated portion of the mRNA encoding the polypeptide. One useful transcription termination component is the bovine growth hormone polyadenylation region.

[0457] Suitable host cells for cloning or expressing the DNA in the vectors herein include higher eukaryotic cells described herein, including vertebrate host cells.Propagation of vertebrate cells in culture (tissue culture) has become a routine procedure. Examples of useful mammalian host cell lines are monkey kidney CV1 line transformed by SV40 (COS-7, ATCC CRL 1651); human embryonic kidney line (293 cells or 293 cells subcloned for growth in suspension culture, Graham et al., J. Gen Virol. 36:59 (1977)); baby hamster kidney cells (BHK, ATCC CCL 10); Chinese hamster ovary cells / -DHFR (CHO, Urlaub et al., Proc. Natl. Acad. Sci. USA 77:4216 (1980)); mouse Sertoli cells (TM4, Mather, Biol. Reprod. 23:243-251 (1980)); monkey kidney cells (CV1, ATCC CCL 70); African green monkey kidney cells (VERO-76, ATCC CRL-1587); human cervical carcinoma cells (HELA, ATCC CCL 2); canine kidney cells (MDCK, ATCC CCL34); Buffalo rat liver cells (BRL 3A, ATCC CRL 1442); human lung cells (W138, ATCC CCL 75); human hepatocytes (Hep G2, HB 8065); mouse mammary tumor (MMT 060562, ATCC CCL51); TRI cells (Mather et al., Annals NY Acad. Sci. 383:44-68 (1982)); MRC 5 cells; FS4 cells; and a human hepatoma line (HepG2).

[0458] Host cells can be transformed with the expression or cloning vectors described above to produce antibodies and cultured in conventional nutrient media modified as appropriate to induce promoters, select transformants, or amplify the genes encoding the desired sequences.

[0459] Host cells for producing the antibodies of the present application can be cultured in a variety of culture media. Commercially available culture media such as Ham's F10 (Sigma), Minimum Essential Medium (MEM) (Sigma), RPMI-1640 (Sigma) and Dulbecco's Modified Eagle's Medium (DMEM) (Sigma) are suitable for culturing host cells. In addition, any culture medium described in Ham et al., Meth.Enz.58:44 (1979), Barnes et al., Anal.Biochem.102:255 (1980), U.S. Patent Nos. 4,767,704; 4,657,866; 4,927,762; 4,560,655; or 5,122,469; WO 90 / 03430; WO 87 / 00195; or U.S. Reissue Patent No. 30,985 can be used as a culture medium for host cells. Any of these media may be supplemented as needed with hormones and / or other growth factors (such as insulin, transferrin, or epidermal growth factor), salts (such as sodium chloride, calcium, magnesium, and phosphate), buffers (such as HEPES), nucleotides (such as adenosine and thymidine), antibiotics (such as GENTAMYCIN TM Drugs), trace elements (defined as inorganic compounds typically present at final concentrations in the micromolar range), and glucose or an equivalent energy source. Any other necessary supplements may also be included at appropriate concentrations known to those skilled in the art. Culture conditions (such as temperature, pH, etc.) are those previously used with the host cell selected for expression and will be apparent to the skilled artisan.

[0460] When using recombinant technology, antibody can be produced in cell, in periplasmic space, or directly secreted in substratum.If antibody produces in cell, then as the first step, for example, by centrifugal or ultrafiltration, remove the particle debris of host cell or cleavage fragment.When antibody is secreted in substratum, usually first use commercially available protein concentration filter (for example, Amicon or Millipore Pellicon ultrafiltration unit) to concentrate the supernatant from this type of expression system.Can comprise protease inhibitors such as PMSF to inhibit proteolysis in any aforementioned ste...

Claims

1. An antibody or antigen-binding fragment thereof that binds ACVR2A, wherein the affinity of the antibody or antigen-binding fragment for ACVR2A is at least 10 times greater than the affinity for ACVR2B, and wherein optionally the antibody or antigen-binding fragment comprises: a heavy chain complementary determining region 1 (HCDR1), a heavy chain complementary determining region 2 (HCDR2), and a heavy chain complementary determining region 3 (HCDR3) as shown in SEQ ID NO: 12, and a light chain complementary determining region 1 (LCDR1), a light chain complementary determining region 2 (LCDR2), and a light chain complementary determining region 3 (LCDR3) as shown in SEQ ID NO:

38.

2. The antibody or antigen-binding fragment according to claim 1, wherein HCDR1 comprises the amino acid sequence of SEQ ID NO:57, HCDR2 comprises the amino acid sequence of SEQ ID NO:43, HCDR3 comprises the amino acid sequence of SEQ ID NO:44, LCDR1 comprises the amino acid sequence of SEQ ID NO:45, LCDR2 comprises the amino acid sequence of SEQ ID NO:69, and LCDR3 comprises the amino acid sequence of SEQ ID NO:

47.

3. The antibody or antigen-binding fragment according to claim 1 or 2, comprising: A VH comprising the amino acid sequence of SEQ ID NO:12, and a VL comprising the amino acid sequence of SEQ ID NO:

38.

4. The antibody or antigen-binding fragment according to any one of claims 1 to 3, wherein The antibody is IgG.

5. The antibody according to any one of claims 1 to 4, wherein The antibodies are human antibodies.

6. The antibody according to any one of claims 1 to 5, wherein The antibody or antigen-binding fragment thereof is genetically fused or chemically conjugated to the agent.

7. A nucleic acid molecule encoding the antibody or antigen-binding fragment according to any one of claims 1 to 6. A vector comprising the nucleic acid molecule according to claim 7 .

9. A host cell transformed with the vector according to claim 8.

10. A composition comprising a therapeutically effective amount of the antibody or antigen-binding fragment according to any one of claims 1 to 6, the nucleic acid molecule according to claim 7, or the vector according to claim 8, and a pharmaceutically acceptable excipient.

11. Use of the composition according to claim 10 in the preparation of a medicament for treating a disease or condition of a subject, wherein: The medicament will be administered to the subject.

12. The use according to claim 11, wherein The disease or condition is associated with ACVR2A.

13. The use according to claim 11, wherein The disease or condition is associated with an ACVR2A ligand.

14. The use according to claim 11, wherein The disease or disorder is associated with activin A, GDF8 or GDF11.

15. The use according to any one of claims 11 to 14, wherein The disease or disorder is a musculoskeletal disease or disorder.

16. The use according to claim 15, wherein The musculoskeletal disease or disorder is selected from the group consisting of: muscular atrophy, spinal muscular atrophy and cancer cachexia.

17. The use according to any one of claims 11 to 14, wherein The disease or disorder is an age-related condition selected from the group consisting of sarcopenia, skin atrophy, muscle wasting, brain atrophy, atherosclerosis, arteriosclerosis, emphysema, osteoporosis, osteoarthritis, immunodeficiency, hypertension, dementia, Huntington's disease, Alzheimer's disease, cataracts, age-related macular degeneration, prostate cancer, stroke, shortened life expectancy, frailty, memory loss, wrinkles, impaired renal function and age-related hearing loss.

18. The use according to any one of claims 11 to 14, wherein The disease or disorder is a metabolic disorder selected from the group consisting of type II diabetes, metabolic syndrome, hyperglycemia, NASH and obesity.

19. The use according to any one of claims 11 to 14, wherein The disease or disorder is selected from the group consisting of acute and / or chronic renal disease or renal failure, liver fibrosis or cirrhosis, pulmonary fibrosis, pulmonary hypertension, renal fibrosis, Parkinson's disease, ALS, brain atrophy, dementia cachexia, bone loss.

20. The use according to any one of claims 11 to 14, wherein The disease or condition is a cancer selected from the group consisting of sarcoma, ovarian cancer, breast cancer, esophageal cancer, head and neck cancer, lung cancer, melanoma, multiple myeloma, colorectal cancer, hepatocellular carcinoma, pancreatic cancer, endometrial cancer, and gastrointestinal cancer.

21. The use according to any one of claims 11 to 14, wherein The disease or condition is anemia.

22. The use according to any one of claims 11 to 21, wherein A second agent is further administered to the subject.

23. The use according to claim 22, wherein The second agent is an ACVR2B antagonist, wherein optionally the ACVR2B antagonist is the ACVR2B extracellular domain fusion protein Rotecept.

24. The use according to claim 22, wherein The second agent is an anti-PD-L1 antibody.

25. The use according to claim 22, wherein The second agent is a chemotherapeutic agent, such as carboplatin.

26. A method for inhibiting or antagonizing ACVR2A in a cell, the method comprising contacting the cell with the composition of claim 10.

27. The composition of claim 10 for use in therapy.

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