IGG-binding molecules and methods of use thereof

Abstract

Provided herein are IgG-binding molecules that specifically bind to IgG (e.g., human IgG) in a pH-dependent manner, and methods of use thereof. Nucleic acids, vectors, host cells, and methods of manufacture relating to these IgG-binding molecules are also provided.

Description

Docket No. ARGX-T2501 / 01 WOIGG-BINDING MOLECULES AND METHODS OF USE THEREOFRELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No.63 / 743,925, filed January 10, 2025, the entire disclosure of which is hereby incorporated herein by reference.FIELD

[0002] The present disclosure relates to IgG-binding molecules and methods of using the same.BACKGROUND

[0003] Immunoglobulin gamma (IgG) antibodies play a key role in the pathology of many disorders, such as autoimmune diseases, inflammatory diseases, and disorders in which the pathology is characterized by over-expression of IgG antibodies.

[0004] Agents that can produce a rapid, deep, and sustained reduction in serum concentration of IgG hold great promise for the treatment of IgG-mediated disorders.SUMMARY

[0005] The instant disclosure is broadly directed to IgG-binding molecules that specifically bind to IgG (e.g., human IgG) in a pH-dependent manner, and methods of use thereof. Such IgG-binding molecules are particularly advantageous because, in some embodiments, they are capable of producing a rapid, deep, and sustained reduction in serum concentration of IgG in a subject. In some embodiments, the IgG-binding molecules disclosed herein have been engineered to not bind to variant human Fc regions comprising amino acids Y, T, E, K, F, and Y at EU positions 252, 254, 256, 433, 434, and 436. This innovation has multiple benefits. For example, it allows a patient to be treated with a combination of an IgG-binding molecule disclosed herein and an therapeutic IgG antibody comprising a variant Fc region with Y, T, E, K, F, and Y at EU positions 252, 254, 256, 433, 434, and 436 without accelerated clearance of the therapeutic IgG antibody from a patient’s serum. Furthermore, IgG-binding molecules disclosed herein that comprise a variant Fc region with Y, T, E, K, F, and Y at EU positions 252, 254, 256, 433, 434, and 436 will not be1329912564Docket No. ARGX-T2501 / 01 WOsubject to self-clearance. Accordingly, the IgG-binding molecules disclosed herein hold great promise as therapeutic agents for the treatment of IgG-mediated disorders.

[0006] In an aspect, provided herein is an IgG-binding molecule comprising an IgG-binding domain, wherein the IgG-binding domain: a) specifically binds to human IgGl, human IgG2, human IgG3, or human IgG4, and b) does not specifically bind to the amino acid sequence set forth in SEQ IDNO: 1.

[0007] In some embodiments, the IgG-binding domain specifically binds to the amino acid sequence of SEQ ID NO: 454, 455, 456, or 457. In some embodiments, the IgG-binding domain specifically binds to the amino acid sequence of SEQ ID NO: 454, 455, 456, and 457.

[0008] In some embodiments, the IgG-binding domain has a higher affinity for human IgGl, human IgG2, human IgG3, or human IgG4 at pH 7.4 than at pH 5.5.

[0009] In an aspect, provided herein is an IgG-binding molecule comprising an IgG-binding domain, wherein the IgG-binding domain specifically binds to human IgGl, human IgG2, human IgG3, or human IgG4 with higher affinity at pH 7.4 than at pH 5.5.

[0010] In some embodiments, the IgG-binding domain specifically binds to human IgGl, human IgG2, human IgG3, and human IgG4.

[0011] In some embodiments, the IgG-binding domain has a higher affinity for human IgGl at pH 7.4 than at pH 5.5. In some embodiments, the IgG-binding domain has a higher affinity for human IgGl, human IgG2, and human IgG4 at pH 7.4 than at pH 5.5. In some embodiments, the IgG-binding domain has a higher affinity for human IgGl, human IgG2, human IgG3, and human IgG4 at pH 7.4 than at pH 5.5. In some embodiments, the ratio of KD for IgG at pH 5.5 and KD for IgG at pH 7.4 is at least 2. In some embodiments, the IgG-binding domain specifically binds to IgG with nanomolar affinity at pH 7.4 and does not specifically bind to IgG at pH 5.5.

[0012] In some embodiments, the IgG-binding domain comprises:(a) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 428, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 451;(b) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 357, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 389;2329912564Docket No. ARGX-T2501 / 01 WO(c) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 358, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 390;(d) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 359, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 391;(e) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 360, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 392;(f) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 361, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 393;(g) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 362, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 394;(h) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 363, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 395;(i) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 364, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 396;(j) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 365, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 397;(k) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 366, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 398;(l) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 367, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 399;3329912564Docket No. ARGX-T2501 / 01 WO(m) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 368, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 400;(n) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 369, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 401;(o) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 370, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 402;(p) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 371, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 403;(q) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 372, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 404;(r) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 373, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 405;(s) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 374, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 406;(t) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 375, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 407;(u) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 376, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 408;(v) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 377, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 409;4329912564Docket No. ARGX-T2501 / 01 WO(w) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 378, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 410;(x) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 379, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 411;(y) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 380, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 412;(z) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 381, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 413;(aa) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 382, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 414;(bb) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 383, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 415;(cc) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 384, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 416;(dd) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 385, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 417;(ee) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 386, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 418;(ff) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 387, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 419; or5329912564Docket No. ARGX-T2501 / 01 WO(gg) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 388, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 420.

[0013] In an aspect, provided herein is an IgG-binding molecule that specifically binds to human IgG, comprising an IgG-binding domain comprising:(a) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 428, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 451;(b) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 357, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 389;(c) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 358, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 390;(d) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 359, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 391;(e) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 360, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 392;(f) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 361, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 393;(g) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 362, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 394;(h) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 363, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 395;(i) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 364, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 396;6329912564Docket No. ARGX-T2501 / 01 WO(j) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 365, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 397;(k) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 366, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 398;(l) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 367, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 399;(m) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 368, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 400;(n) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 369, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 401;(o) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 370, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 402;(p) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 371, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 403;(q) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 372, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 404;(r) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 373, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 405;(s) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 374, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 406;7329912564Docket No. ARGX-T2501 / 01 WO(t) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 375, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 407;(u) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 376, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 408;(v) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 377, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 409;(w) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 378, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 410;(x) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 379, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 411;(y) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 380, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 412;(z) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 381, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 413;(aa) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 382, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 414;(bb) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 383, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 415;(cc) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 384, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 416;8329912564Docket No. ARGX-T2501 / 01 WO(dd) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 385, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 417;(ee) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 386, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 418;(ff) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 387, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 419; or(gg) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 388, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 420.

[0014] In some embodiments, the CDRH1, CDRH2, CDRH3, CDRL1, CDRL2, and CDRL3 amino acid sequences, respectively, comprise the amino acid sequences set forth in SEQ ID NOs: 183, 184, 185, 348, 349, and 350; 69, 70, 71, 225, 226, and 227; 72, 73, 74, 228, 229, and 230; 75, 76, 77, 231, 232, and 233; 78, 79, 80, 234, 235, and 236; 81, 82, 83, 237, 238, and 239; 84, 85, 86, 240, 241, and 242; 87, 88, 89, 243, 244, and 245; 90, 91, 92, 246, 247, and 248; 93, 94, 95, 249, 250, and 251; 96, 97, 98, 252, 253, and 254; 99, 100, 101, 255, 256, and 257; 102, 103, 104, 258, 259, and 260; 105, 106, 107, 261, 262, and 263; 108, 109, 110, 264, 265, and 266; 111, 112, 113, 267, 268, and 269; 114, 115, 116, 270, 271, and 272; 117, 118, 119, 273, 274, and 275; 120, 121, 122, 276, 277, and 278; 123, 124, 125, 279, 280, and 281; 126, 127, 128, 282, 283, and 284; 129, 130, 131, 285, 286, and 287; 132, 133, 134, 288, 289, and 290; 135, 136, 137, 291, 292, and 293; 138, 139, 140, 294, 295, and 296; 141, 142, 143, 297, 298, and 299; 144, 145, 146, 300, 301, and 302; 147, 148, 149, 303, 304, and 305; 150, 151, 152, 306, 307, and 308; 153, 154, 155, 309, 310, and 311; 156, 157, 158, 312, 313, and 314; 159, 160, 161, 315, 316, and 317; or 162, 163, 164, 318, 319, and 320.

[0015] In some embodiments, the VH comprises an amino acid sequence at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence set forth in any one of SEQ ID NOs: 357-388 and 422-441. In some embodiments, the VH comprises an amino acid sequence set forth in any one of SEQ ID NOs: 357-388 and 422-441.9329912564Docket No. ARGX-T2501 / 01 WO

[0016] In some embodiments, the VL comprises an amino acid sequence at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence set forth in any one of SEQ ID NOs: 389-420 and 443-453. In some embodiments, the VL comprises an amino acid sequence set forth in any one of SEQ ID NOs: 389-420 and 443-453.

[0017] In some embodiments, the VH and VL, respectively, comprise the amino acid sequences set forth in SEQ ID NOs: 428 and 451, 357 and 389, 358 and 390, 359 and 391, 360 and 392, 361 and 393, 362 and 394, 363 and 395, 364 and 396, 365 and 397, 366 and 398, 367 and 399, 368 and 400, 369 and 401, 370 and 402, 371 and 403, 372 and 404, 373 and 405, 374 and 406, 375 and 407, 376 and 408, 377 and 409, 378 and 410, 379 and 411, 380 and 412, 381 and 413, 382 and 414, 383 and 415, 384 and 416, 385 and 417, 386 and 418, 387 and 419, or 388 and 420, respectively.

[0018] In some embodiments, the IgG-binding domain is a Fab. In some embodiments, the Fab comprises a human IgG CHI domain. In some embodiments, the human IgG CHI domain comprises the amino acid sequence set forth in SEQ ID NO: 33. In some embodiments, the Fab comprises a human light chain constant domain. In some embodiments, the human light chain constant domain comprises the amino acid sequence set forth in SEQ ID NO: 46.

[0019] In some embodiments, the IgG-binding molecule further comprises a means for binding to FcRn with higher affinity at pH 7.4 relative to a wild-type Fc region.

[0020] In some embodiments, the IgG-binding molecule does not specifically bind to the amino acid sequence set forth in SEQ ID NO: 1.

[0021] In some embodiments, the IgG-binding molecule specifically binds to human IgGl, human IgG2, human IgG3, and human IgG4.

[0022] In some embodiments, the IgG-binding molecule has a higher affinity for human IgGl, human IgG2, human IgG3, or human IgG4 at pH 7.4 than at pH 5.5. In some embodiments, the IgG-binding molecule has a higher affinity for human IgGl, human IgG2, and human IgG4 at pH 7.4 than at pH 5.5. In some embodiments, the IgG-binding molecule has a higher affinity for human IgGl, human IgG2, human IgG3, and human IgG4 at pH 7.4 than at pH 5.5.

[0023] In some embodiments, the IgG-binding molecule further comprises a variant Fc region that binds to FcRn with higher affinity at pH 7.4 relative to the corresponding wild-type Fc region.10329912564Docket No. ARGX-T2501 / 01 WO

[0024] In an aspect, provided herein is a composition comprising an IgG-binding molecule comprising: a means for specifically binding to human IgGl, human IgG2, human IgG3, and / or human IgG4, that does not does not specifically bind to the amino acid sequence set forth in SEQ ID NO: 1; and, optionally, a pharmaceutically acceptable excipient. In an aspect, provided herein is a composition comprising an IgG-binding molecule comprising: a means for specifically binding to human IgGl, human IgG2, and / or human IgG4 with a higher affinity at pH 7.4 than at pH 5.5; and, optionally, a pharmaceutically acceptable excipient. In an aspect, provided herein is an IgG-binding molecule comprising: a means for specifically binding to the amino acid sequence of SEQ ID NO: 454, 455, 456, or 457; and, optionally, a pharmaceutically acceptable excipient. In an aspect, provided herein is an IgG-binding molecule comprising: a means for specifically binding to the amino acid sequence of SEQ ID NO: 454, 455, 456, and 457; and, optionally, a pharmaceutically acceptable excipient.

[0025] In an aspect, provided herein is an IgG-binding molecule comprising: a means for specifically binding to human IgGl, human IgG2, human IgG3, and / or human IgG4, that does not does not specifically bind to the amino acid sequence set forth in SEQ ID NO: 1; and a variant Fc region (e.g., a variant Fc region disclosed herein) that binds to FcRn with higher affinity at pH 7.4 relative to the corresponding wild-type Fc region. In an aspect, provided herein is an IgG-binding molecule comprising: a means for specifically binding to human IgGl, human IgG2, and / or human IgG4 with a higher affinity at pH 7.4 than at pH 5.5; and a variant Fc region (e.g., a variant Fc region disclosed herein) that binds to FcRn with higher affinity at pH 7.4 relative to the corresponding wild-type Fc region. In an aspect, provided herein is an IgG-binding molecule comprising: a means for specifically binding to the amino acid sequence of SEQ ID NO: 454, 455, 456, or 457; and a variant Fc region (e.g., a variant Fc region disclosed herein) that binds to FcRn with higher affinity at pH 7.4 relative to the corresponding wild-type Fc region. In an aspect, provided herein is an IgG-binding molecule comprising: a means for specifically binding to the amino acid sequence of SEQ ID NO: 454, 455, 456, and 457; and a variant Fc region (e.g., a variant Fc region disclosed herein) that binds to FcRn with higher affinity at pH 7.4 relative to the corresponding wild-type Fc region.

[0026] In an aspect, provided herein is an IgG-binding molecule comprising: a means for binding to human IgGl, human IgG2, human IgG3, or human IgG4; and a variant Fc region that binds to FcRn with higher affinity at pH 7.4 relative to the corresponding wild-type Fc region.11329912564Docket No. ARGX-T2501 / 01 WO

[0027] In some embodiments, the IgG-binding molecule does not specifically bind to the amino acid sequence set forth in SEQ ID NO: 1.

[0028] In some embodiments, the IgG-binding molecule specifically binds to human IgGl, human IgG2, human IgG3, and human IgG4.

[0029] In some embodiments, the IgG-binding molecule has a higher affinity for human IgGl, human IgG2, human IgG3, or human IgG4 at pH 7.4 than at pH 5.5. In some embodiments, the IgG-binding molecule has a higher affinity for human IgGl, human IgG2, and human IgG4 at pH 7.4 than at pH 5.5. In some embodiments, the IgG-binding molecule has a higher affinity for human IgGl, human IgG2, human IgG3, and human IgG4 at pH 7.4 than at pH 5.5.

[0030] In some embodiments, the variant Fc region is a variant IgGl Fc region. In some embodiments, the variant Fc region binds to FcRn at pH 6.0 with an affinity that is at least 20 times greater than the affinity of the corresponding wild-type human IgG Fc region for FcRn. In some embodiments, the variant Fc region binds to FcRn at pH 6.0 with a KD or 15 nM or less. In some embodiments, the variant Fc region comprises a first Fc domain and a second Fc domain which form a dimer, wherein the first Fc domain and the second Fc domain comprise amino acids Y, T, E, K, F, and Y at EU positions 252, 254, 256, 433, 434, and 436, respectively.

[0031] In some embodiments, the variant Fc region comprises one or more mutations that reduce or eliminate Fc effector function. In some embodiments, the first Fc domain and / or the second Fc domain comprise amino acids A and A at EU positions 234 and 235. In some embodiments, the first Fc domain and / or the second Fc domain comprise amino acid G or A at EU position 329.

[0032] In some embodiments, the first Fc domain and the second Fc domain comprise amino acids A, A, Y, T, E, G, K, F, and Y, at EU positions 234, 235, 252, 254, 256, 329, 433, 434, and 436, respectively.

[0033] In some embodiments, the variant Fc region comprises one or more mutations that promote dimerization between the first Fc domain and the second Fc domain. In some embodiments, the first Fc domain and the second Fc domain comprise knob-into-holes amino acid mutations. In some embodiments, the first Fc domain comprises amino acid W at EU position 366, and the second Fc domain comprises amino acids S, A, and V at EU positions 366, 368, and 407, respectively.

[0034] In some embodiments, the first Fc domain comprises amino acids A, A, Y, T, E, G, W, K, F, and Y at EU positions 234, 235, 252, 254, 256, 329, 366, 433, 434, and 436, respectively,12329912564Docket No. ARGX-T2501 / 01 WOand the second Fc domain comprises amino acids A, A, Y, T, E, G, S, A, V, K, F, and Y at EU positions 234, 235, 252, 254, 256, 329, 366, 368, 407, 433, 434, and 436, respectively.

[0035] In some embodiments, the IgG-binding domain is linked to the first Fc domain, e.g., the N-terminus of the first Fc domain. In some embodiments, the IgG-binding domain is linked to the second Fc domain, e.g., the N-terminus of the second Fc domain.

[0036] In some embodiments, the first Fc domain comprises or consists of the amino acid sequence set forth in SEQ ID NO: 17 and / or the second Fc domain comprises or consists of the amino acid sequence set forth in SEQ ID NO: 20.

[0037] In an aspect, provided herein is an IgG-binding molecule comprising an IgG-binding domain and a variant IgGl Fc region, wherein the variant IgGl Fc region comprises a first Fc domain and a second Fc domain which form a dimer, wherein the first Fc domain and the second Fc domain comprise amino acids Y, T, E, K, F, and Y at EU positions 252, 254, 256, 433, 434, and 436, respectively, and wherein the IgG-binding domain: a) specifically binds to human IgGl, human IgG2, human IgG3, or human IgG4, and b) does not specifically bind to the variant IgGl Fc region.

[0038] In some embodiments, the IgG-binding molecule comprises no more than one IgG-binding domain. In some embodiments, the IgG-binding domain is linked to the N-terminal end of the first Fc domain. In some embodiments the IgG-binding domain is linked to the N-terminal end of the second Fc domain.

[0039] In some embodiments, the IgG-binding domain specifically binds to human IgGl, human IgG2, human IgG3, and human IgG4.

[0040] In some embodiments, the IgG-binding domain has a higher affinity for human IgGl, human IgG2, human IgG3, or human IgG4 at pH 7.4 than pH 5.5. In some embodiments, the IgG-binding domain has a higher affinity for human IgGl at pH 7.4 than pH 5.5. In some embodiments, the IgG-binding domain has a higher affinity for human IgGl, human IgG2, and human IgG4 at pH 7.4 than pH 5.5. In some embodiments, the IgG-binding domain has a higher affinity for human IgGl, human IgG2, human IgG3, and human IgG4 at pH 7.4 than pH 5.5. In some embodiments, the ratio of KD for IgG at pH 5.5 and KD for IgG at pH 7.4 is at least 2. In some embodiments, the IgG-binding domain specifically binds to IgG with nanomolar affinity at pH 7.4 and does not specifically bind to IgG at pH 5.5.

[0041] In some embodiments, the IgG-binding domain is a Fab. In some embodiments, the Fab comprises a human IgG CHI domain. In some embodiments, the human IgG CHI domain 13329912564Docket No. ARGX-T2501 / 01 WOcomprises the amino acid sequence set forth in SEQ ID NO: 33. In some embodiments, the Fab comprises a human light chain constant domain. In some embodiments, the human light chain constant domain comprises the amino acid sequence set forth in SEQ ID NO: 46.

[0042] In some embodiments, the IgG-binding domain comprises:(a) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 428, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 451;(b) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 357, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 389;(c) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 358, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 390;(d) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 359, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 391;(e) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 360, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 392;(f) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 361, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 393;(g) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 362, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 394;(h) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 363, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 395;(i) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 364, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 396;14329912564Docket No. ARGX-T2501 / 01 WO(j) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 365, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 397;(k) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 366, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 398;(l) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 367, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 399;(m) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 368, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 400;(n) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 369, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 401;(o) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 370, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 402;(p) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 371, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 403;(q) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 372, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 404;(r) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 373, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 405;(s) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 374, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 406;15329912564Docket No. ARGX-T2501 / 01 WO(t) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 375, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 407;(u) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 376, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 408;(v) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 377, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 409;(w) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 378, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 410;(x) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 379, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 411;(y) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 380, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 412;(z) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 381, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 413;(aa) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 382, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 414;(bb) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 383, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 415;(cc) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 384, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 416;16329912564Docket No. ARGX-T2501 / 01 WO(dd) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 385, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 417;(ee) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 386, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 418;(ff) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 387, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 419; or(gg) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 388, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 420.

[0043] In some embodiments, the CDRH1, CDRH2, CDRH3, CDRL1, CDRL2, and CDRL3 amino acid sequences, respectively, comprise the amino acid sequences set forth in SEQ ID NOs: 183, 184, 185, 348, 349, and 350; 69, 70, 71, 225, 226, and 227; 72, 73, 74, 228, 229, and 230; 75, 76, 77, 231, 232, and 233; 78, 79, 80, 234, 235, and 236; 81, 82, 83, 237, 238, and 239; 84, 85, 86, 240, 241, and 242; 87, 88, 89, 243, 244, and 245; 90, 91, 92, 246, 247, and 248; 93, 94, 95, 249, 250, and 251; 96, 97, 98, 252, 253, and 254; 99, 100, 101, 255, 256, and 257; 102, 103, 104, 258, 259, and 260; 105, 106, 107, 261, 262, and 263; 108, 109, 110, 264, 265, and 266; 111, 112, 113, 267, 268, and 269; 114, 115, 116, 270, 271, and 272; 117, 118, 119, 273, 274, and 275; 120, 121, 122, 276, 277, and 278; 123, 124, 125, 279, 280, and 281; 126, 127, 128, 282, 283, and 284; 129, 130, 131, 285, 286, and 287; 132, 133, 134, 288, 289, and 290; 135, 136, 137, 291, 292, and 293; 138, 139, 140, 294, 295, and 296; 141, 142, 143, 297, 298, and 299; 144, 145, 146, 300, 301, and 302; 147, 148, 149, 303, 304, and 305; 150, 151, 152, 306, 307, and 308; 153, 154, 155, 309, 310, and 311; 156, 157, 158, 312, 313, and 314; 159, 160, 161, 315, 316, and 317; or 162, 163, 164, 318, 319, and 320.

[0044] In some embodiments, the VH comprises an amino acid sequence at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence set forth in any one of SEQ ID NOs: 357-388 and 422-441. In some embodiments, the VH comprises the amino acid sequence set forth in any one of SEQ ID NOs: 357-388 and 422-441.17329912564Docket No. ARGX-T2501 / 01 WO

[0045] In some embodiments, the VL comprises an amino acid sequence at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence set forth in any one of SEQ ID NOs: 389-420 and 443-453. In some embodiments, the VL comprises the amino acid sequence set forth in any one of SEQ ID NOs: 389-420 and 443-453.

[0046] In some embodiments, the VH comprises the CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 428, and the VL comprises the CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 451.

[0047] In some embodiments, the CDRH1, CDRH2, CDRH3, CDRL1, CDRL2, and CDRL3 amino acid sequences are set forth in SEQ ID NOs: 183, 184, 185, 348, 349, and 350, respectively.

[0048] In some embodiments, the VH comprises an amino acid sequence at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence set forth in SEQ ID NO: 428. In some embodiments, the VH comprises the amino acid sequence set forth in SEQ ID NO: 428.

[0049] In some embodiments, the VL comprises an amino acid sequence at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence set forth in SEQ ID NO: 451. In some embodiments, the VL comprises the amino acid sequence set forth in SEQ ID NO: 451.

[0050] In some embodiments, the variant IgGl Fc region comprises one or more mutations that reduce or eliminate Fc effector function. In some embodiments, the first Fc domain and / or the second Fc domain comprise amino acids A and A at EU positions 234 and 235. In some embodiments, the first Fc domain and / or the second Fc domain comprise amino acid G or A at EU position 329.

[0051] In some embodiments, the first Fc domain and the second Fc domain comprise amino acids A, A, Y, T, E, G, K, F, and Y, at EU positions 234, 235, 252, 254, 256, 329, 433, 434, and 436, respectively.

[0052] In some embodiments, the variant IgGl Fc region comprises one or more mutations that promote dimerization between the first Fc domain and the second Fc domain. In some embodiments, the first Fc domain and the second Fc domain comprise knob-into-holes amino acid mutations. In some embodiments, the first Fc domain comprises amino acid W at EU position 366,18329912564Docket No. ARGX-T2501 / 01 WOand the second Fc domain comprises amino acids S, A, and V at EU positions 366, 368, and 407, respectively.

[0053] In some embodiments, the first Fc domain comprises amino acids A, A, Y, T, E, G, W, K, F, and Y at EU positions 234, 235, 252, 254, 256, 329, 366, 433, 434, and 436, respectively, and the second Fc domain comprises amino acids A, A, Y, T, E, G, S, A, V, K, F, and Y at EU positions 234, 235, 252, 254, 256, 329, 366, 368, 407, 433, 434, and 436, respectively.

[0054] In some embodiments, the first Fc domain comprises or consists of the amino acid sequence set forth in SEQ ID NO: 17 and / or the second Fc domain comprises or consists of the amino acid sequence set forth in SEQ ID NO: 20.

[0055] In some embodiments, the IgG-binding molecule comprises a first polypeptide comprising or consisting of the amino acid sequence set forth in SEQ ID NO: 38. In some embodiments, the IgG-binding molecule comprises a second polypeptide comprising or consisting of the amino acid sequence set forth in SEQ ID NO: 20. In some embodiments, the IgG-binding molecule comprises a third polypeptide comprising or consisting of the amino acid sequence set forth in SEQ ID NO: 56.

[0056] In an aspect, provided herein is an IgG-binding molecule comprising: a first polypeptide comprising or consisting of the amino acid sequence set forth in SEQ ID NO: 38; a second polypeptide comprising or consisting of the amino acid sequence set forth in SEQ ID NO: 20; and a third polypeptide comprising or consisting of the amino acid sequence set forth in SEQ ID NO: 56.

[0057] In some embodiments, the IgG-binding molecule does not reduce serum albumin levels. In some embodiments, the IgG-binding molecule does not induce FcRn degradation.

[0058] Also provided herein is an isolated polynucleotide or polynucleotides encoding any of the IgG-binding molecules described herein.

[0059] Also provided herein is an expression vector comprising any of the isolated polynucleotide or polynucleotides described herein.

[0060] Also provided herein is a host cell comprising any of the isolated polynucleotide or polynucleotides or any of the expression vectors described herein.

[0061] Also provided herein is a method for producing an IgG-binding molecule, comprising culturing any of the host cells described herein under conditions which permit the expression of the IgG-binding molecule.19329912564Docket No. ARGX-T2501 / 01 WO

[0062] Also provided herein is a composition comprising any of the IgG-binding molecules described herein, and at least one pharmaceutically acceptable carrier.

[0063] Also provided herein is any of the IgG-binding molecules described herein for use as a medicament.

[0064] Also provided herein is a method of reducing serum IgG in a subject in need thereof comprising administering to the subject a therapeutically effective amount of any of the IgG-binding molecules described herein, or any of the compositions described herein.

[0065] Also provided herein is a method of treating an antibody-mediated disorder in a subject in need thereof comprising administering to the subject a therapeutically effective amount of any of the IgG-binding molecules described herein, or any of the compositions described herein. In some embodiments, the antibody-mediated disorder is an IgG-mediated disorder. In some embodiments, the antibody-mediated disorder is an autoimmune disease.

[0066] Also provided herein is an IgG-binding molecule, or a composition, for use in the treatment of an antibody-mediated disorder.

[0067] Also provided herein is an IgG-binding molecule, for the manufacture of a medicament for treating an antibody-mediated disorder.BRIEF DESCRIPTION OF THE DRAWINGS

[0068] FIG. 1 is a graph showing FcRn occupancy by one-armed (OA)-anti-IgGl -huIgGl -ABDEG antibodies without immune complexing. The percentage unoccupied hFcRn is plotted against concentration of the anti-IgG antibodies. The IC50 values are calculated for each antibody in nM. Data is presented relative to 100% free FcRn receptor in untreated U937 cells.

[0069] FIGs. 2A-2B are graphs showing the effect of OA-anti-IgGl-huIgGl-ABDEG antibodies on FcRn degradation in HEK FcRn WT GFP+ cells (FIG.2A) or U937 cells (FIG.2B) in the presence or absence of huIgGl. The percentage hFcRn compared to the untreated cells is plotted for all five OA-anti-IgG-huIgGl-ABDEG antibodies both in complex (IC: full bars) and without complex (striped bars) to huIgGl . Error bars are shown for the samples measured in duplicate, ns = p >0.1234; *** p >0.0001.

[0070] FIG. 3 is a graph showing PK profiles in AlbuMus RaglKO mice after a single IP injection of OA-mAb37-ABDEG (control), OA-01A07-ABDEG (non-pH-dependent), OA-02A10-ABDEG (mild pH dependent) and OA-05A01-ABDEG (strong pH dependent). Serum 20329912564Docket No. ARGX-T2501 / 01 WOconcentrations of the test items were plotted as an average per group over time. The datapoints show the mean ± SD of 4-5 mice per group.

[0071] FIGs. 4A-4B are graphs showing the PD effect of OA-anti-IgGl-huIgGl-ABDEG antibodies in AlbuMus RaglKO mice. Change in total IgG concentrations was plotted over time (days post-injection) both as total concentrations (FIG. 4A) and as % to pre-dose on day 0,-5min (FIG. 4B). The data are depicted as the mean ± SEM of 3-5 animals per group per timepoint.

[0072] FIG. 5 is a graph showing PK profiles in AlbuMus RaglKO mice after a single IP injection of an equimolar dose of ARGX-113 (20 mg / kg), OA-02A10-ABDEG (40 mg / kg), OA-02A10-LALAPG-ABDEG (40 mg / kg), OA-02A10-YPY (40 mg / kg), OA-02A10-YY (40 mg / kg), OA-05A01-ABDEG (40 mg / kg) and serum concentrations were measured over 14 days. Serum concentrations of the different test articles are plotted as mean ± SD of 5 animals per group over time, during the course of the study.

[0073] FIGs. 6A-6B are graphs showing the PD effect of OA-anti-IgGl-huIgGl-ABDEG antibodies in AlbuMus RaglKO mice. Change in total IgG concentrations was plotted over time (days post-injection) both as total concentrations (FIG. 6A) and as % to pre-dose on day 0,-5min (FIG. 6B). The data are depicted as the mean ± SEM of 3-5 animals per group per timepoint.

[0074] FIG. 7 is a graph showing PK profiles in hFcgR hFcRn knock-in mice after a single IV injection of OA-02A10-ABDEG (40 mg / kg) or OA-02A10-LALAPG-ABDEG (40 mg / kg), and serum concentrations were sampled over 7 days. Serum concentrations of the different test articles are plotted as mean ± SD of 5 animals per group over time, during the course of the study.

[0075] FIGs. 8A-8B are graphs showing the PD effect of OA-02A10-ABDEG or OA-02A10-LALAPG-ABDEG in hFcgR hFcRn knock-in mice. Change in total IgG concentrations was plotted over time (days post-injection) both as total concentrations (FIG.8A) and as % to predose on day 0,-2h (FIG.8B). The data are depicted as the mean ± SD of 3-5 animals per group per timepoint.

[0076] FIG. 9 is a set of sensorgrams assessing the dissociation rate constant of OA-02A10 liability / histidine variants for Fc huIgGl-WT at pH 6.0.

[0077] FIG. 10 is a graph showing PK profiles in AlbuMus RaglKO mice after a single IV injection of 4 mg / kg of OA-02A10 liability / histidine variants. Serum concentrations of the different test articles are plotted as mean ± SD of 3-5 animals per group overtime during the course of the study.21329912564Docket No. ARGX-T2501 / 01 WO

[0078] FIGs. 11A-11B are graphs showing the PD effect of OA-02A10 liability / histidine variants in AlbuMus RaglKO mice. Change in total IgG concentrations was plotted over time (days post-injection) both as total concentrations (FIG. 11 A) and as % to pre-dose on day 0,-5min (FIG. 11B). The data are depicted as the mean ± SD of 3-5 animals per group per timepoint.

[0079] FIG. 12A is a graph showing the PK profile of various doses of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG administered as a single IV administration in cynomolgus monkeys. FIG. 12B is a graph showing the PD effect of various doses of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG administered as a single IV administration in cynomolgus monkeys. Change in serum IgG levels was plotted over time (days post-injection) as % to pre-dose (baseline) levels.

[0080] FIG. 13 is a set of sensorgrams assessing the dissociation rate constant of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG to different IgG subclasses at pH 7.4 and pH 6.0. Sensorgrams with corresponding fitting represent 3 independent runs using a 1 : 1 binding kinetics fit model. The KD values represent the mean of 3 independent runs ± standard deviation.

[0081] FIG. 14A is a graph showing the PD effect of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG compared to ARGX-113 administered as a single IV administration in Tg32 SCID (hFcRn+) mice. Change in tracer IgG3 levels was plotted over time (days post-injection) as % to pre-dose (baseline) levels. FIG. 14B is a graph showing the PK profile of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG compared to ARGX-113 administered as a single IV administration in Tg32 SCID (hFcRn+) mice.

[0082] FIGs. 15A-15B are graphs showing the PD effect of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG compared to OA-02A10-GLLiab5-Hisl-LALAPG-ABDEG administered as a single IV administration in AlbuMus RaglKO mice. Changes in total IgG (FIG. 15A) and tracer IgG3 (FIG. 15B) levels were plotted over time (days post-injection) as % to pre-dose (baseline) levels. FIG. 15C is a graph showing the PK profile of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG compared to OA-02A10-GLLiab5-Hisl-LALAPG-ABDEG administered as a single IV administration in AlbuMus RaglKO mice.DETAILED DESCRIPTION

[0083] The instant disclosure is broadly directed to IgG-binding molecules that specifically bind IgG (e.g., human IgG) in a pH-dependent manner, and methods of use thereof. Nucleic acids 22329912564Docket No. ARGX-T2501 / 01 WOencoding such IgG-binding molecules, vectors, host cells, methods of manufacture, and methods for their use in treating antibody-mediated disorders are also provided herein.Definitions

[0084] As used herein, the term “FcRn” refers to a neonatal Fc receptor. Exemplary FcRn molecules include human FcRn encoded by the FCGRT gene as set forth in RefSeq NM 004107. The amino acid sequence of the corresponding protein is set forth in RefSeq NP 004098.

[0085] As used herein, the term “FcRn antagonist” refers to any agent that specifically binds to FcRn and inhibits the binding of immunoglobulin to FcRn (e.g., human FcRn). In an embodiment, the FcRn antagonist comprises an Fc region (e.g., a variant Fc region disclosed herein) that specifically binds to FcRn through the Fc region and inhibits the binding of immunoglobulin to FcRn. In an embodiment, the FcRn antagonist is not a full-length IgG antibody. In an embodiment, the FcRn antagonist comprises an IgG-binding domain that binds a target antigen and a variant Fc region. In an embodiment, the term “FcRn antagonist” refers to an antibody or antigen-binding fragment thereof that specifically binds to FcRn via its antigen binding domain and / or via its Fc region and inhibits the binding of the Fc region of immunoglobulin (e.g., IgG autoantibodies) to FcRn.

[0086] As used herein, the term “affinity” or “binding affinity” refers to the strength of the binding interaction between two molecules. As used herein, the term “equilibrium dissociation constant” or “KD” refers to the propensity of bound complex of two molecules to dissociate into two free molecules. Thus, as the binding affinity increases, the KD decreases.

[0087] As used herein, the term “specifically binds” refers to the ability of any molecule to preferentially bind with a given target. For example, a molecule that specifically binds to a given target can bind to other molecules, generally with lower affinity as determined by, e.g., immunoassays, BIAcore™ 8K+ instrument (Sapidyne Instruments, Boise, Id.), or other assays known in the art. In a specific embodiment, molecules that specifically bind to a given target bind to the antigen with a KD that is at least 2 logs, 2.5 logs, 3 logs, 4 logs or less than the KD when the molecules bind non-specifically to another target.

[0088] As used herein, the term “operably linked” refers to a linkage of polynucleotide sequence elements in a functional relationship. For example, a polynucleotide sequence is operably linked when it is placed into a functional relationship with another polynucleotide sequence. In some embodiments, a transcription regulatory polynucleotide sequence, e.g., a promoter,23329912564Docket No. ARGX-T2501 / 01 WOenhancer, or other expression control element is operably linked to a polynucleotide sequence that encodes a protein if it affects the transcription of the polynucleotide sequence that encodes the protein. Operably linked elements may be contiguous or non-contiguous.

[0089] As used herein, the term “linked” refers to a physical linkage (e.g., directly or indirectly linked) between amino acid sequences (e.g., different segments, regions, fragments, or domains). Linked regions, fragments, domains, and segments of the polypeptides of the disclosure may be contiguous or non-contiguous (e.g., linked to one another through a linker). In some embodiments, two proteins are directly and contiguously fused together by a peptide bond. In some embodiments, two proteins are indirectly and non-contiguously fused through a peptide linker. In some embodiments, one protein is fused to a peptide linker by a peptide bond at a first position, and a second protein is fused to a peptide linker by a peptide bond at a second position.

[0090] 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 specific, non-limiting example of a mathematical algorithm utilized for the comparison of two sequences is the algorithm of Karlin S & Altschul SF, (1990) PNAS 87: 2264-2268, modified as in Karlin S & Altschul SF, (1993) PNAS 90: 5873-5877, each of which is herein incorporated by reference in its entirety. Such an algorithm is incorporated into the NBLAST and XBLAST programs of Altschul SF et al., (1990) J Mol Biol 215: 403, which is herein incorporated by reference in its entirety. BLAST nucleotide searches can be performed with the NBLAST nucleotide program parameters set, e.g., at score=100, wordlength=12 to obtain nucleotide sequences homologous to a nucleic acid molecule described herein. BLAST protein searches can be performed with the XBLAST program parameters set, e.g., at score=50, wordlength=3 to obtain amino acid sequences homologous to a protein molecule described herein. To obtain gapped alignments for comparison purposes, Gapped BLAST can be utilized as described in Altschul SF et al., (1997) Nuc Acids Res 25: 3389-3402, which is herein incorporated by reference in its entirety. Alternatively, PSI BLAST can be used to perform an iterated search which detects distant relationships between molecules. Id. When utilizing BLAST, Gapped BLAST, and PSI BLAST programs, the default parameters of the respective programs (e.g, of XBLAST and NBLAST) can be used (see, e.g., National Center for Biotechnology Information (NCBI) on the worldwide web, ncbi.nlm.nih.gov). Another specific, non-limiting example of a mathematical algorithm utilized for the comparison of sequences is the algorithm of Myers and Miller, (1988) CABIOS 4:11-17, which is herein incorporated by reference in its entirety. Such an algorithm is incorporated in the 24329912564Docket No. ARGX-T2501 / 01 WOALIGN program (version 2.0) which is part of the GCG sequence alignment software package. When utilizing the ALIGN program for comparing amino acid sequences, a PAM 120 weight residue table, a gap length penalty of 12, and a gap penalty of 4 can be used.

[0091] The percent identity between two sequences can be determined using techniques similar to those described above, with or without allowing gaps. In calculating percent identity, typically only exact matches are counted.

[0092] As used herein, the terms “antibody” and “antibodies” include full-length antibodies, antigen-binding fragments of full-length antibodies, and molecules comprising antibody CDRs, VH domains (VH), or VL domains (VL). Examples of antibodies include monoclonal antibodies, recombinantly produced antibodies, monospecific antibodies, multispecific antibodies (including bispecific antibodies), human antibodies, humanized antibodies, chimeric antibodies, immunoglobulins, synthetic antibodies, tetrameric antibodies comprising two heavy chain and two light chain molecules, an antibody light chain monomer, an antibody heavy chain monomer, an antibody light chain dimer, an antibody heavy chain dimer, an antibody light chain-antibody heavy chain pair, intrabodies, heteroconjugate antibodies, antibody-drug conjugates, single-domain antibodies (sdAb), monovalent antibodies, single chain antibodies or single-chain Fvs (scFv), camelid antibodies, affibody molecules, VHH, Fab, F(ab')2, disulfide-linked Fvs (sdFv), anti-idiotypic (anti-Id) antibodies (including, e.g., anti-anti-Id antibodies), and antigen-binding fragments of any of the above. Antibodies can be of any isotype (e.g., IgG, IgE, IgM, IgD, IgA, or IgY), any subclass (e.g., IgGi, IgG2, IgGs, IgG4, IgAi, or IgA2), or species (e.g., mouse IgG2a or IgG2b) of immunoglobulin molecule.

[0093] As used herein, “IgG” refers to immunoglobulin gamma. In some embodiments, IgG comprises human IgG. In some embodiments. IgG comprises immunoglobulin gamma 1 (“IgGl”), immunoglobulin gamma 2 (“IgG2”), immunoglobulin gamma 3 (“IgG3”), or immunoglobulin gamma 4 (“IgG4”). In some embodiments, IgG comprises human IgGl, human IgG2, human IgG3, or human IgG4. An exemplary amino acid sequence of human IgGl is encoded by the nucleotide sequence provided at GenelD: 3500, incorporated herein by reference. An exemplary amino acid sequence of human IgG2 is encoded by the nucleotide sequence provided at GenelD: 3501, incorporated herein by reference. An exemplary amino acid sequence of human IgG3 is encoded by the nucleotide sequence provided at GenelD: 3502, incorporated herein by reference. An exemplary amino acid sequence of human IgG4 is encoded by the nucleotide sequence provided at GenelD: 3503, incorporated herein by reference.25329912564Docket No. ARGX-T2501 / 01 WO

[0094] As used herein, the term “IgG-binding domain” or “IgG binding domain” refers to any polypeptide or protein that specifically binds to a constant region of IgG. In some embodiments, the IgG binding domain specifically binds to the CH2 and or CH3 domains of IgG. In some embodiments, the IgG is a human IgG. In some embodiments, the human IgG is human IgGl . In some embodiments, the IgG binding domain specifically binds to the amino acid sequence of KDTLMISRT (SEQ ID NO: 454). In some embodiments, the IgG binding domain specifically binds to the amino acid sequence of VFSCSVMHEALHNF1YTQKS (SEQ ID NO:455). In some embodiments, the IgG binding domain specifically binds to the amino acid sequence of SEQ ID NO: 454 and the amino acid sequence of TVLHQ (SEQ ID NO: 456). In some embodiments, the IgG binding domain specifically binds to the amino acid sequence of SEQ ID NO: 454 and the amino acid sequence of AVEWESNGQP (SEQ ID NO:457). In some embodiments, the IgG binding domain specifically binds to the amino acid sequence of SEQ ID NOs: 454, 456, and 457. In some embodiments, the IgG binding domain specifically binds to the amino acid sequence of SEQ ID NOs: 455 and 456; 455 and 457; 454 and 455; 454, 455, and 456; or 454, 455, 456, and 457.

[0095] Examples of IgG-binding domains include polypeptides derived from antibodies, such as Fab, F(ab')2, disulfide-linked Fvs (sdFv), single-chain Fvs (scFv), CDRs, VH domains (VH), VL domains (VL), single-domain antibodies (sdAb), VHH, camelid antibodies, and IgG-binding fragments of any of the above. The term also encompasses synthetic IgG-binding proteins or antibody mimetic proteins such as, for example, anticalins and DARPins.

[0096] As used herein, the terms “variable region” or “variable domain” are used interchangeably and are common in the art. The variable region typically refers to a portion of an antibody, generally, a portion of a light or heavy chain, typically about the amino-terminal 110 to 120 amino acids in the mature heavy chain and about 90 to 115 amino acids in the mature light chain, which differ extensively in sequence among antibodies and are used in the binding and specificity of a particular antibody for its particular antigen. The variability in sequence is concentrated in those regions called complementarity determining regions (CDRs) while the more highly conserved regions in the variable domain are called framework regions (FR). For example, in general, there are three CDRs in each heavy chain variable region (e.g., CDRH1, CDRH2, and CDRH3) and three CDRs in each light chain variable region (CDRL1, CDRL2, and CDRL3). Without wishing to be bound by any particular mechanism or theory, it is believed that the CDRs26329912564Docket No. ARGX-T2501 / 01 WOof the light and heavy chains are primarily responsible for the interaction and specificity of the antibody with antigen. In certain embodiments, the variable region is a human variable region.

[0097] The terms “VL” and “VL domain” are used interchangeably to refer to the light chain variable region of an antibody.

[0098] The terms “VH” and “VH domain” are used interchangeably to refer to the heavy chain variable region of an antibody.

[0099] As used herein, the term “constant region” or “constant domain” are interchangeable and have its meaning common in the art. The constant region is an antibody portion, e.g., a carboxyl terminal portion of a light and / or heavy chain which is not directly involved in binding of an antibody to antigen, but which can exhibit various effector functions, such as interaction with the Fc receptor. The constant region of an immunoglobulin molecule generally has a more conserved amino acid sequence relative to an immunoglobulin variable domain.

[0100] As used herein, the term “heavy chain” when used in reference to an antibody can refer to any distinct type, e.g., alpha (a), delta (5), epsilon (a), gamma (y), and mu (p), based on the amino acid sequence of the constant domain, which give rise to IgA, IgD, IgE, IgG, and IgM classes of antibodies, respectively, including subclasses of IgG, e.g., IgGl, IgG2, IgG3, and IgG4. In specific embodiments, the heavy chain is a human heavy chain.

[0101] As used herein, the term “light chain” when used in reference to an antibody can refer to any distinct type, e.g., kappa (K) or lambda ( ) based on the amino acid sequence of the constant domains. Light chain amino acid sequences are well known in the art. In specific embodiments, the light chain is a human light chain.

[0102] As used herein, the term “Fc region” refers to the portion of an immunoglobulin formed by the Fc domains of its two heavy chains. The Fc region can be a wild-type Fc region (native Fc region) or a variant Fc region. A native Fc region is homodimeric. The Fc region can be derived from any native immunoglobulin. In some embodiments, the Fc region is formed from an IgA, IgD, IgE, or IgG heavy chain constant region. In some embodiments, the Fc region is formed from an IgG heavy chain constant region. In some embodiments, the IgG heavy chain is an IgGl, IgG2, IgG3, or IgG4 heavy chain constant region. In some embodiments, the Fc region is formed from an IgGl heavy chain constant region. In some embodiments, the IgGl heavy chain constant region comprises a Glml(a), Glm2(x), Glm3(f), or Glml7(z) allotype. See, e.g., Jefferis27329912564Docket No. ARGX-T2501 / 01 WOand Lefranc (2009) mAbs 1(4): 332-338, and de Taeye et al., (2020) Front Immunol. 11: 740, incorporated herein by reference in their entirety.

[0103] As used herein, the term “variant Fc region” refers to a variant of an Fc region with one or more alteration(s) relative to a native Fc region. Alterations can include amino acid substitutions, additions and / or deletions, linkage of additional moieties, and / or alteration of the native glycans. The term encompasses heterodimeric Fc regions where each of the constituent Fc domains is different. The term also encompasses single chain Fc regions where the constituent Fc domains are linked together by a linker moiety.

[0104] As used herein, the term “Fc domain” refers to the portion of a single immunoglobulin heavy chain comprising both the CH2 and CH3 domains of the antibody. In some embodiments, the Fc domain comprises at least a portion of a hinge (e.g., upper, middle, and / or lower hinge region) region, a CH2 domain, and a CH3 domain. In some embodiments, the Fc domain does not include the hinge region.

[0105] As used herein, the term “hinge region” refers to the portion of a heavy chain molecule that joins the CHI domain to the CH2 domain. In some embodiments, the hinge region is at most 70 amino acid residues in length. In some embodiments, this hinge region comprises approximately 11-17 amino acid residues and is flexible, thus allowing the two N-terminal antigen binding regions to move independently. In some embodiments, the hinge region is 12 amino acid residues in length. In some embodiments, the hinge region is 15 amino acid residues in length. In some embodiments, the hinge region is 62 amino acid residues in length. Hinge regions can be subdivided into three distinct domains: upper, middle, and lower hinge domains. The polypeptides of the instant disclosure can include all or any portion of a hinge region. In some embodiments, the hinge region is from an IgGl antibody. In some embodiments, the hinge region comprises the amino acid sequence of EPKSCDKTHTCPPCP (SEQ ID NO: 68).

[0106] As used herein, the term “FcRn-binding fragment” refers to a portion of an FcRn-binding molecule, e.g., a portion of an Fc region, that is sufficient to confer FcRn binding.

[0107] As used herein, the terms, “one-armed,” “one armed,” “one-arm,” “one arm,” or “OA” refers to a polypeptide or a protein comprising an Fc region linked to only one IgG-binding domain. In some embodiments, “one-armed,” “one armed,” “one-arm,” “one arm,” or “OA” refers to a polypeptide comprising an Fc region comprising the Fc domains of two heavy chains, wherein one of the Fc domains of the two heavy chains is linked to an IgG-binding domain and the other Fc domain of the two heavy chains is not linked to an IgG-binding domain. In some embodiments,28329912564Docket No. ARGX-T2501 / 01 WOthe IgG-binding domain is linked to the N-terminus of one of the Fc domains of the two heavy chains. In some embodiments, the IgG-binding domain is linked to the C-terminus of one of the Fc domains of the two heavy chains.

[0108] As used herein, the term “EU position” refers to the amino acid position in the EU numbering convention for the Fc region described in Edelman, GM et al. Proc. Natl. Acad. USA, 63, 78-85 (1969) and Kabat et al., in “Sequences of Proteins of Immunological Interest,” U.S. Dept. Health and Human Services, 5thedition, 1991.

[0109] As used herein, the term, “antibody-mediated disorder” refers to any disorder wherein the symptoms of the disorder are caused by abnormal levels of one or more antibodies in a subject. As used herein, the term “autoantibody-mediated disorder” refers to any disease or disorder in which the underlying pathology is caused, at least in part, by pathogenic IgG autoantibodies.

[0110] As used herein, the term “treat,” “treating,” and “treatment” refer to therapeutic or preventative measures described herein. The methods of “treatment” employ administration of a polypeptide to a subject having a disease or disorder, or predisposed to having such a disease or disorder, in order to prevent, cure, delay, reduce the severity of, or ameliorate one or more symptoms of the disease or disorder or recurring disease or disorder, or in order to prolong the survival of a subject beyond that expected in the absence of such treatment. In some embodiments, the methods of “treatment” employ administration of a polypeptide to a subject having a disease or disorder, or predisposed to having such a disease or disorder, in order to prevent, cure, delay, reduce the severity of, or ameliorate the disease or disorder or recurring disease or disorder.

[0111] As used herein, the term “effective amount” in the context of the administration of a therapy to a subject refers to the amount of a therapy that achieves a desired prophylactic or therapeutic effect.

[0112] As used herein, the term “dose” or “dosing” refers to an amount of an agent administered to a subject in a single administration.

[0113] As used herein, the terms “pharmacodynamics,” and “PD,” refer to the biological effect of a therapeutic agent on an organism. In some embodiments, the biological effect is modulation of the amount of circulating IgG in an organism administered a therapeutic agent. In some embodiments, the therapeutic agent is an anti-IgG molecule of the disclosure.

[0114] As used herein, the terms “pharmacokinetics,” and “PK,” refer to the effect of an organism on a therapeutic agent administered to the organism. In some embodiments, the effect is 29329912564Docket No. ARGX-T2501 / 01 WOmetabolization and / or clearance of the therapeutic agent. In some embodiments, PK refers to the rate of metabolization and / or clearance of the therapeutic agent. In some embodiments, the therapeutic agent is an anti-IgG molecule of the disclosure.

[0115] As used herein, the term “subject” or “patient” or “participant” includes any human or non-human animal. In an embodiment, the subject or patient or participant is a human or nonhuman mammal. In an embodiment, the subject or patient or participant is a human.

[0116] As used herein, the term “about” or “approximately” when referring to a measurable value, such as a dosage, encompasses variations of ±5% of a given value or range, as are appropriate to perform the methods disclosed herein.IgG-Binding Domains

[0117] In some embodiments, the IgG-binding domain is selected from a Fab, an scFv, an sdAb, a VH, a VL, and IgG-binding fragments thereof. In some embodiments, the IgG-binding domain is a synthetic IgG-binding protein or antibody mimetic protein including, but not limited to, an anticalin or a DARPin. In some embodiments, the IgG-binding domain is a Fab.

[0118] In some embodiments, the term “IgG” includes IgGl, IgG2, IgG3, or IgG4. In some embodiments, IgG is human IgG. In some embodiments, the term “human IgG” includes human IgGl, human IgG2, human IgG3, or human IgG4.

[0119] In some embodiments, the IgG-binding domains described herein exhibit pH-dependent antigen binding, z.e., pH-dependent binding to IgG. As used herein, “pH-dependent binding” means that the IgG-binding domain exhibits lower IgG binding affinity at an acidic pH than at a neutral pH. pH-dependent IgG binding is advantageous since it results in enhanced IgG sweeping from serum.

[0120] In some embodiments, the IgG-binding domain has a higher affinity for IgG at pH 7.4 than at pH 5.5. In some embodiments, the IgG-binding domain has a higher affinity for human IgG at pH 7.4 than at pH 5.5. In some embodiments, the IgG-binding domain has a higher affinity for IgGl at pH 7.4 than at pH 5.5. In some embodiments, the IgG-binding domain has a higher affinity for human IgGl at pH 7.4 than at pH 5.5. In some embodiments, the IgG-binding domain has a higher affinity for IgG2 at pH 7.4 than at pH 5.5. In some embodiments, the IgG-binding domain has a higher affinity for human IgG2 at pH 7.4 than at pH 5.5. In some embodiments, the IgG-binding domain has a higher affinity for IgG3 at pH 7.4 than at pH 5.5. In some embodiments, the IgG-binding domain has a higher affinity for human IgG3 at pH 7.4 than at pH 5.5. In some 30329912564Docket No. ARGX-T2501 / 01 WOembodiments, the IgG-binding domain has a higher affinity for IgG4 at pH 7.4 than at pH 5.5. In some embodiments, the IgG-binding domain has a higher affinity for human IgG4 at pH 7.4 than at pH 5.5.

[0121] In some embodiments, the IgG-binding domain has a higher affinity for IgG at pH 7.4 than at pH 6.0. In some embodiments, the IgG-binding domain has a higher affinity for human IgG at pH 7.4 than at pH 6.0. In some embodiments, the IgG-binding domain has a higher affinity for IgGl at pH 7.4 than at pH 6.0. In some embodiments, the IgG-binding domain has a higher affinity for human IgGl at pH 7.4 than at pH 6.0. In some embodiments, the IgG-binding domain has a higher affinity for IgG2 at pH 7.4 than at pH 6.0. In some embodiments, the IgG-binding domain has a higher affinity for human IgG2 at pH 7.4 than at pH 6.0. In some embodiments, the IgG-binding domain has a higher affinity for IgG3 at pH 7.4 than at pH 6.0. In some embodiments, the IgG-binding domain has a higher affinity for human IgG3 at pH 7.4 than at pH 6.0. In some embodiments, the IgG-binding domain has a higher affinity for IgG4 at pH 7.4 than at pH 6.0. In some embodiments, the IgG-binding domain has a higher affinity for human IgG4 at pH 7.4 than at pH 6.0.

[0122] The pH-dependent IgG-binding may be characterized in that the dissociation constant (KD) for the IgG-binding domain-IgG interaction at acidic pH or pH 5.5 is higher than the dissociation constant (KD) for the IgG-binding domain-IgG interaction at neutral pH or pH 7.4. In some embodiments, the IgG-binding domain exhibits pH-dependent binding such that the ratio of KD for IgG at pH 5.5 and KD for IgG at pH 7.4 (KD (pH 5.5) / KD (pH 7.4)) is at least 1.5, at least 2, at least 4, at least 6, at least 8, at least 10, at least 12, at least 14, at least 16, at least 18, or at least 20.

[0123] In some embodiments, the IgG-binding domain specifically binds to IgG at a neutral pH and does not specifically bind to IgG at an acidic pH. In some embodiments, the IgG-binding domain binds to IgG with nanomolar affinity at a neutral pH and does not specifically bind to IgG at an acidic pH. In some embodiments, the IgG-binding domain binds to IgG at a neutral pH with a KD < 100 nM and binds to IgG with a KD > 100 nM at an acidic pH. In some embodiments, the IgG-binding domain binds to IgG at a neutral pH with a KD < 90 nM, 80 nM, 70 nM, 60 nM, 50 nM, 40 nM, 30 nM, 25 nM, 20 nM, 15 nM, or 10 nM, and binds to IgG with a KD > 100 nM, 200 nM, 300 nM, 400 nM, 500 nM, 600 nM, 700 nM, 800 nM, 900 nM, or 1 pM at an acidic pH. In some embodiments, acidic pH is about pH 5.0, about pH 5.5, or about pH 6.0. In31329912564Docket No. ARGX-T2501 / 01 WOsome embodiments, neutral pH is about pH 7.4. In some embodiments, acidic pH is pH 5.0, pH 5.5, or pH 6.0. In some embodiments, neutral pH is pH 7.4.

[0124] The pH-dependent IgG-binding activity of an IgG-binding domain may be engineered by modifying the domain to impair IgG binding affinity at acidic pH and / or to increase IgG binding affinity at neutral pH. The IgG-binding domain may be modified by substituting at least one amino acid of the IgG-binding domain with histidine, or by inserting at least one histidine into the IgG-binding domain. Such histidine mutation (substitution or insertion) sites are not particularly limited, and any site is acceptable as long as the IgG binding activity at endosomal pH (e.g., pH 5.5) is lower than that at serum pH (e.g., pH 7.4) when compared to the IgG-binding domain without the mutation or insertion.

[0125] In some embodiments, the IgG-binding domain is engineered to exhibit pH-dependent IgG binding by the introduction of one or more substitutions, into a framework region of the IgG-binding domain. The substitutions may introduce one or more His residues into one or more sites of a framework region to confer pH-dependent IgG binding.

[0126] In some embodiments, the IgG-binding domain is engineered to exhibit pH-dependent IgG binding by the introduction of one or more substitutions into a variable region or domain of the IgG-binding domain. In some embodiments, the IgG-binding domain is engineered to exhibit pH-dependent IgG binding by introducing one or more substitutions into one or more CDRs of a variable region or domain of the IgG-binding domain. The substitutions may introduce one or more His residues into one or more sites of a variable region or domain, preferably the heavy chain and / or light chain CDRs to confer pH-dependent IgG binding.

[0127] For embodiments in which the IgG-binding domain comprises a variable region comprising three heavy chain CDR sequences and three light chain CDR sequences, the six CDRs combined may consist of a total of 1-10 His substitutions, optionally 1-5 His substitutions, optionally 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 His substitutions.

[0128] The IgG-binding domains may be engineered in accordance with the methods described in WO2018 / 206748, incorporated herein by reference. Non-histidine substitutions may also be incorporated into variable domains, particularly the CDRs, of the IgG-binding domains described herein.

[0129] In some embodiments, exemplary IgG-binding domains having the particular CDR, VH, and / or VL domain sequences described herein are engineered such that they exhibit pH-dependent IgG binding. For example, the CDR sequences of the exemplary IgG-binding domains 32329912564Docket No. ARGX-T2501 / 01 WOdescribed herein may be modified by the introduction of one or more histidine substitutions to produce IgG-binding domains exhibiting pH-dependent IgG binding and / or enhanced pH-dependent IgG binding.

[0130] Calcium-dependent antigen binding can be used as an alternative to pH-dependent antigen binding to facilitate antigen sweeping. Calcium ion concentration is known to be lower in endosomes as compared to the serum. Therefore, a molecule that exhibits calcium-dependent IgG binding can be used to achieve enhanced IgG sweeping in an analogous manner to a molecule with pH-dependent IgG binding. As such, in some embodiments, the IgG-binding domains described herein exhibit calcium-dependent IgG binding. In some embodiments, the IgG-binding domains described herein exhibit lower IgG binding affinity at lower calcium ion concentrations as compared to IgG binding affinity at higher calcium ion concentrations.

[0131] In some embodiments, the IgG-binding domain does not specifically bind to one or more FcRn antagonists. In some embodiments, the FcRn antagonist comprises one or more of the Fc domains disclosed herein. In some embodiments, the IgG-binding domain binds to one or more FcRn antagonists with a KD > 100 nM. In some embodiments, the IgG-binding domain binds to FcRn antagonists with a KD > 100 nM, 200 nM, 300 nM, 400 nM, 500 nM, 600 nM, 700 nM, 800 nM, 900 nM, or 1 pM.

[0132] Exemplary amino acid sequences of IgG-binding domains are provided in Tables 1-5 below.Table 1: VH CDR Sequences of selected anti-IgG clones33329912564Docket No. ARGX-T2501 / 01 WO34329912564Docket No. ARGX-T2501 / 01 WO35329912564Docket No. ARGX-T2501 / 01 WOTable 2: VL CDR Sequences of selected anti-IgG clones36329912564Docket No. ARGX-T2501 / 01 WO37329912564Docket No. ARGX-T2501 / 01 WO38329912564Docket No. ARGX-T2501 / 01 WOTable 3: VH and VL sequences of selected anti-IgG clones39329912564Docket No. ARGX-T2501 / 01 WO40329912564Docket No. ARGX-T2501 / 01 WO41329912564Docket No. ARGX-T2501 / 01 WO42329912564Docket No. ARGX-T2501 / 01 WO43329912564Docket No. ARGX-T2501 / 01 WOTable 4: VH sequences of selected anti-IgG clones44329912564Docket No. ARGX-T2501 / 01 WOTable 5: VL sequences of selected anti-IgG clones45329912564Docket No. ARGX-T2501 / 01 WO

[0133] In some embodiments, the IgG-binding domain comprises a VH comprising the CDRH1, CDRH2, and CDRH3 of a VH comprising an amino acid sequence selected from SEQ ID NOs: 357-388 and 422-441, and a VL comprising the CDRL1, CDRL2, and CDRL3 of a VL comprising an amino acid sequence selected from SEQ ID NOs: 389-420 and 443-453.

[0134] In some embodiments, the IgG-binding domain comprises a combination of CDRH1, CDRH2, CDRH3, CDRL1, CDRL2, and CDRL3, wherein 1, 2, 3, 4, or 5 amino acids differ in at least one of the amino acid sequences selected from SEQ ID NOs: 183, 184, 185, 348,46329912564Docket No. ARGX-T2501 / 01 WO349, and 350; 69, 70, 71, 225, 226, and 227; 72, 73, 74, 228, 229, and 230; 75, 76, 77, 231, 232, and 233; 78, 79, 80, 234, 235, and 236; 81, 82, 83, 237, 238, and 239; 84, 85, 86, 240, 241, and 242; 87, 88, 89, 243, 244, and 245; 90, 91, 92, 246, 247, and 248; 93, 94, 95, 249, 250, and 251; 96, 97, 98, 252, 253, and 254; 99, 100, 101, 255, 256, and 257; 102, 103, 104, 258, 259, and 260; 105, 106, 107, 261, 262, and 263; 108, 109, 110, 264, 265, and 266; 111, 112, 113, 267, 268, and 269; 114, 115, 116, 270, 271, and 272; 117, 118, 119, 273, 274, and 275; 120, 121, 122, 276, 277, and 278; 123, 124, 125, 279, 280, and 281; 126, 127, 128, 282, 283, and 284; 129, 130, 131, 285, 286, and 287; 132, 133, 134, 288, 289, and 290; 135, 136, 137, 291, 292, and 293; 138, 139, 140, 294, 295, and 296; 141, 142, 143, 297, 298, and 299; 144, 145, 146, 300, 301, and 302; 147, 148, 149, 303, 304, and 305; 150, 151, 152, 306, 307, and 308; 153, 154, 155, 309, 310, and 311; 156, 157, 158, 312, 313, and 314; 159, 160, 161, 315, 316, and 317; or 162, 163, 164, 318, 319, and 320, respectively.

[0135] In some embodiments, the IgG-binding domain comprises a combination of CDRH1, CDRH2, CDRH3, CDRL1, CDRL2, and CDRL3 selected from SEQ ID NOs: 183, 184, 185, 348, 349, and 350; 69, 70, 71, 225, 226, and 227; 72, 73, 74, 228, 229, and 230; 75, 76, 77, 231, 232, and 233; 78, 79, 80, 234, 235, and 236; 81, 82, 83, 237, 238, and 239; 84, 85, 86, 240, 241, and 242; 87, 88, 89, 243, 244, and 245; 90, 91, 92, 246, 247, and 248; 93, 94, 95, 249, 250, and 251; 96, 97, 98, 252, 253, and 254; 99, 100, 101, 255, 256, and 257; 102, 103, 104, 258, 259, and 260; 105, 106, 107, 261, 262, and 263; 108, 109, 110, 264, 265, and 266; 111, 112, 113, 267, 268, and 269; 114, 115, 116, 270, 271, and 272; 117, 118, 119, 273, 274, and 275; 120, 121, 122, 276, 277, and 278; 123, 124, 125, 279, 280, and 281; 126, 127, 128, 282, 283, and 284; 129, 130, 131, 285, 286, and 287; 132, 133, 134, 288, 289, and 290; 135, 136, 137, 291, 292, and 293; 138, 139, 140, 294, 295, and 296; 141, 142, 143, 297, 298, and 299; 144, 145, 146, 300, 301, and 302; 147, 148, 149, 303, 304, and 305; 150, 151, 152, 306, 307, and 308; 153, 154, 155, 309, 310, and 311; 156, 157, 158, 312, 313, and 314; 159, 160, 161, 315, 316, and 317; or 162, 163, 164, 318, 319, and 320, respectively.

[0136] In some embodiments, the IgG-binding domain comprises a VH comprising or consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to an amino acid sequence selected from SEQ ID NOs: 357-388 and 422-441, and a VL comprising or consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to an amino acid sequence selected from SEQ ID NOs: 389-420 and 443-453.47329912564Docket No. ARGX-T2501 / 01 WO

[0137] In some embodiments, the IgG-binding domain comprises a VH comprising or consisting of an amino acid sequence selected from SEQ ID NOs: 357-388 and 422-441, and a VL comprising or consisting of an amino acid sequence selected from SEQ ID NOs: 389-420 and 443-453.

[0138] In some embodiments, the IgG-binding domain comprises a VH and a VL each comprising or consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to an amino acid sequence selected from SEQ ID NOs: 428 and 451, 357 and 389, 358 and 390, 359 and 391, 360 and 392, 361 and 393, 362 and 394, 363 and 395, 364 and 396, 365 and 397, 366 and 398, 367 and 399, 368 and 400, 369 and 401, 370 and 402, 371 and 403, 372 and 404, 373 and 405, 374 and 406, 375 and 407, 376 and 408, 377 and 409, 378 and 410, 379 and 411, 380 and 412, 381 and 413, 382 and 414, 383 and 415, 384 and 416, 385 and 417, 386 and 418, 387 and 419, or 388 and 420, respectively.

[0139] In some embodiments, the IgG-binding domain comprises a VH and a VL each comprising or consisting of an amino acid sequence selected from SEQ ID NOs: 428 and 451, 357 and 389, 358 and 390, 359 and 391, 360 and 392, 361 and 393, 362 and 394, 363 and 395, 364 and 396, 365 and 397, 366 and 398, 367 and 399, 368 and 400, 369 and 401, 370 and 402, 371 and 403, 372 and 404, 373 and 405, 374 and 406, 375 and 407, 376 and 408, 377 and 409, 378 and 410, 379 and 411, 380 and 412, 381 and 413, 382 and 414, 383 and 415, 384 and 416, 385 and 417, 386 and 418, 387 and 419, or 388 and 420, respectively.Fc Regions

[0140] In an aspect, the disclosure provides molecules comprising an IgG-binding domain and an Fc region, or FcRn-binding fragment thereof. The IgG-binding domain may be any IgG-binding domain described herein. In some embodiments, the polypeptides disclosed herein comprise one or more IgG-binding domains and an Fc region, or FcRn-binding fragment thereof.

[0141] Any Fc region can be altered to produce a variant Fc region as disclosed herein. In general, an Fc region, or FcRn-binding fragment thereof, is from a human immunoglobulin. It is understood, however, that the Fc region may be derived from an immunoglobulin of any other mammalian species, including for example, a cam elid species, a rodent (e.g., a mouse, rat, rabbit, guinea pig) or non-human primate e.g., chimpanzee, macaque) species. Moreover, the Fc region or FcRn-binding portion thereof may be derived from any immunoglobulin class, including IgM, IgG, IgD, IgA, and IgE, and any immunoglobulin isotype, including IgGl, IgG2, IgG3, and IgG4.48329912564Docket No. ARGX-T2501 / 01 WOIn an embodiment, the Fc region is an IgG Fc region (e.g., a human IgG region). In an embodiment, the Fc region is an IgGl Fc region (e.g., a human IgGl region). In an embodiment, the Fc region is a chimeric Fc region comprising portions of several different Fc regions. Suitable examples of chimeric Fc regions are set forth in US 2011 / 0243966A1, which is incorporated herein by reference in its entirety. A variety of Fc region gene sequences (e.g., human constant region gene sequences) are available in the form of publicly accessible deposits.

[0142] An Fc region can be further truncated or internally deleted to produce a minimal FcRn-binding fragment thereof. The ability of an Fc-region fragment to bind to FcRn can be determined using any art recognized binding assay e.g. , ELISA.

[0143] To enhance the manufacturability of Fc regions, and polypeptides containing the same, as disclosed herein, it is preferable that the constituent Fc regions do not comprise any nondisulfide bonded cysteine residues. Accordingly, in an embodiment, the Fc regions do not comprise a free cysteine residue.

[0144] In some embodiments, the variant Fc region is derived from the Fc region of any native immunoglobulin. In some embodiments, the native immunoglobulin is a human immunoglobulin. In some embodiments, the immunoglobulin is IgA, IgD, IgE, or IgG. In some embodiments, the immunoglobulin is IgG. In some embodiments, the immunoglobulin is human IgA, human IgD, human IgE, or human IgG. In some embodiments, the immunoglobulin is human IgG. In some embodiments, the IgG is IgGl, IgG2, IgG3, or IgG4. In some embodiments, the human IgG is human IgGl, human IgG2, human IgG3, or human IgG4. In some embodiments, the variant Fc region varies from the human IgGl Fc region. In some embodiments, the human IgGl Fc region comprises a Glml(a), Glm2(x), Glm3(f), or Glml7(z) allotype.

[0145] In some embodiments, the variant Fc region, or FcRn-binding fragment thereof comprises or consists of at least one Fc domain. In some embodiments, the variant Fc region comprises or consists of two Fc domains. In some embodiments, the Fc domains are the same. In some embodiments, the Fc domains are different. In certain embodiments, at least one of the variant Fc domains or FcRn-binding fragments described herein comprises at least one amino acid or at least two amino acids selected from the following: 237M; 238A; 239K; 2481; 250A; 250F; 2501; 250M; 250Q; 250S; 250V; 250W; 250Y; 252F; 252W; 252Y; 254T; 255E; 256D; 256E; 256Q; 257A; 257G; 2571; 257L; 257M; 257N; 257S; 257T; 257V; 258H; 265A; 270F; 286A; 286E; 289H; 297A; 298G; 303A; 305A; 307A; 307D; 307F; 307G; 307H; 3071; 307K; 307L; 307M; 307N; 307P; 307Q; 307R; 307S; 307V; 307W; 307Y; 308A; 308F; 3081; 308L; 308M;49329912564Docket No. ARGX-T2501 / 01 WO308P; 308Q; 308T; 309A; 309D; 309E; 309P; 309R; 311A; 311H; 3111; 312A; 312H; 314K; 314R; 315A; 315H; 317A; 325G; 332V; 334L; 360H; 376A; 378V; 380A; 382A; 384A; 385D; 385H; 386P; 387E; 389A; 389S; 424A; 428 A; 428D; 428F; 428G; 428H; 4281; 428K; 428L; 428N; 428P; 428Q; 428S; 428T; 428V; 428W; 428Y; 433K; 434A; 434F; 434H; 434S; 434W; 434Y; 436H; 4361 and 436F, wherein the positions are defined in accordance with EU numbering. EU numbering refers to the convention for the Fc region described in Edelman, G.M. et al., Proc. Natl. Acad. Sci. USA, 63: 78-85 (1969); and Kabat et al., in “Sequences of Proteins of Immunological Interest”, U.S. Dept. Health and Human Services, 5thedition, 1991. In some embodiments, at least one of the variant Fc domains or FcRn-binding fragments described herein comprises 2, 3, 4 or 5 amino acids selected from the following: 237M; 238A; 239K; 2481; 250A; 250F; 2501; 250M; 250Q; 250S; 250V; 250W; 250Y; 252F; 252W; 252Y; 254T; 255E; 256D; 256E; 256Q; 257A; 257G; 2571; 257L; 257M; 257N; 257S; 257T; 257V; 258H; 265A; 270F; 286A; 286E; 289H; 297A; 298G; 303A; 305A; 307A; 307D; 307F; 307G; 307H; 3071; 307K; 307L; 307M; 307N; 307P; 307Q; 307R; 307S; 307V; 307W; 307Y; 308A; 308F; 3081; 308L; 308M; 308P; 308Q; 308T; 309A; 309D; 309E; 309P; 309R; 311A; 311H; 3111; 312A; 312H; 314K; 314R; 315A; 315H; 317A; 325G; 332V; 334L; 360H; 376A; 378V; 380A; 382A; 384A; 385D; 385H; 386P; 387E; 389A; 389S; 424A; 428 A; 428D; 428F; 428G; 428H; 4281; 428K; 428L; 428N; 428P; 428Q; 428S; 428T; 428V; 428W; 428Y; 433K; 434A; 434F; 434H; 434S; 434W; 434Y; 436H; 4361 and 436F, wherein the positions are defined in accordance with EU numbering and wherein any combinations are contemplated.

[0146] In certain embodiments, at least one of the variant Fc domains or FcRn-binding fragments described herein comprises at least one non-naturally occurring amino acid or at least two non-naturally occurring amino acids selected from the following: 234, 235, 236, 239, 240, 241, 243, 244, 245, 247, 252, 254, 256, 262, 263, 264, 265, 266, 267, 269, 296, 297, 298, 299, 313, 325, 326, 327, 328, 329, 330, 332, 333, and 334 as numbered by the EU index as set forth in Kabat. Optionally, at least one of the variant Fc domains may comprise a non-naturally occurring amino acid residue at additional and / or alternative positions known to one skilled in the art (see, e.g., U.S. Pat. Nos. 5,624,821; 6,277,375; 6,737,056; PCT Patent Publications WO 01 / 58957; WO 02 / 06919; WO 04 / 016750; WO 04 / 029207; WO 04 / 035752 and WO 05 / 040217, the contents of which are incorporated by reference herein in their entirety).

[0147] In certain embodiments, at least one of the variant Fc domains comprises at least one non-naturally occurring amino acid or comprises at least two non-naturally occurring amino 50329912564Docket No. ARGX-T2501 / 01 WOacids selected from the group consisting of 234D, 234E, 234N, 234Q, 234T, 234H, 234Y, 2341, 234V, 234F, 235 A, 235D, 235R, 235W, 235P, 235 S, 235N, 235Q, 235T, 235H, 235 Y, 2351, 235V, 235F, 236E, 239D, 239E, 239N, 239Q, 239F, 239T, 239H, 239Y, 2401, 240A, 240T, 240M, 241W, 241L, 241Y, 241E, 241R, 243W, 243L, 243Y, 243R, 243Q, 244H, 245A, 247V, 247G, 252Y, 254T, 256E, 2621, 262A, 262T, 262E, 2631, 263A, 263T, 263M, 264L, 2641, 264W, 264T, 264R, 264F, 264M, 264Y, 264E, 265G, 265N, 265Q, 265Y, 265F, 265V, 2651, 265L, 265H, 265T, 2661, 266A, 266T, 266M, 267Q, 267L, 269H, 269Y, 269F, 269R, 296E, 296Q, 296D, 296N, 296S, 296T, 296L, 2961, 296H, 269G, 297S, 297D, 297E, 298H, 2981, 298T, 298F, 2991, 299L, 299A, 299S, 299V, 299H, 299F, 299E, 313F, 325Q, 325L, 3251, 325D, 325E, 325A, 325T, 325V, 325H, 327G, 327W, 327N, 327L, 328S, 328M, 328D, 328E, 328N, 328Q, 328F, 3281, 328V, 328T, 328H, 328A, 329F, 329H, 329Q, 330K, 330G, 330T, 330C, 330L, 330Y, 330V, 3301, 330F, 330R, 330H, 332D, 332S, 332W, 332F, 332E, 332N, 332Q, 332T, 332H, 332Y, and 332A as numbered by the EU index as set forth in Kabat. Optionally, at least one of the variant Fc domains may comprise additional and / or alternative non-naturally occurring amino acid residues known to one skilled in the art (see, e.g., U.S. Pat. Nos. 5,624,821; 6,277,375; 6,737,056; PCT Patent Publications WO 01 / 58957; WO 02 / 06919; WO 04 / 016750; WO 04 / 029207; WO 04 / 035752 and WO 05 / 040217, the contents of which are incorporated by reference herein in their entirety).

[0148] Other known Fc domain variants that may be used in the compositions disclosed herein include without limitations those disclosed in Ghetie etal., 1997, Nat. Biotech. 15:637-40; Duncan etal., 1988, Nature 332:563-564; Lund etal., 1991, J. Immunol, 147:2657-2662; Lund et al., 1992, Mol. Immunol, 29:53-59; Alegre et al., 1994, Transplantation 57: 1537-1543; Hutchins et al., 1995, Proc Natl. Acad Sci USA, 92: 11980-11984; Jefferis et al., 1995, Immunol Lett., 44: 111-117; Lund etal., 1995, Faseb J., 9: 115-119; Jefferis etal, 1996, Immunol Lett., 54: 101-104; Lund et al., 1996, J. Immunol, 157:4963-4969; Armour etal., 1999, Eur JImmunol 29:2613-2624; Idusogie et al., 2000, J. Immunol, 164:4178-4184; Reddy et al., 2000, J. Immunol, 164: 1925-1933; Xu et al., 2000, Cell Immunol, 200: 16-26; Idusogie et al., 2001, J. Immunol, 166:2571-2575; Shields et al., 2001, J Biol. Chem., 276:6591-6604; Jefferis et al., 2002, Immunol Lett., 82:57-65; Presta et al., 2002, Biochem Soc Trans., 30:487-490); U.S. Pat. Nos. 5,624,821; 5,885,573; 5,677,425; 6,165,745; 6,277,375; 5,869,046; 6,121,022; 5,624,821; 5,648,260; 6,528,624; 6,194,551; 6,737,056; 6,821,505; 6,277,375; U.S. Patent Publication Nos.2004 / 0002587 and PCT Publications WO 94 / 29351; WO 99 / 58572; WO 00 / 42072; WO51329912564Docket No. ARGX-T2501 / 01 WO02 / 060919; WO 04 / 029207; WO 04 / 099249; WO 04 / 063351, the contents of which are incorporated by reference herein in their entirety.

[0149] In an embodiment, the variant Fc region, or FcRn-binding fragment thereof comprises or consists of two Fc domains. In an embodiment, the variant Fc region, or FcRn-binding fragment thereof, comprises at least one Fc domain comprising amino acids Y, T, E, K, and F at EU positions 252, 254, 256, 433, and 434, respectively. In an embodiment, the variant Fc region, or FcRn-binding fragment thereof, comprises at least one Fc domain comprising amino acids Y, T, E, K, F, and Y at EU positions 252, 254, 256, 433, 434, and 436, respectively. In an embodiment, the variant Fc region, or FcRn-binding fragment thereof, comprises one Fc domain comprising amino acids Y, T, E, K, and F at EU positions 252, 254, 256, 433, and 434, respectively, and a second Fc domain comprising amino acid K and F at EU positions 433 and 434, respectively. In an embodiment, the variant Fc region, or FcRn-binding fragment thereof, comprises one Fc domain comprising amino acids Y, T, E, K, F, and Y at EU positions 252, 254, 256, 433, 434, and 436, respectively, and a second Fc domain comprising amino acid K and F at EU positions 433 and 434, respectively. In an embodiment, the variant Fc region, or FcRn-binding fragment thereof consists of two Fc domains, both of which comprise amino acids Y, T, E, K, and F at EU positions 252, 254, 256, 433, and 434, respectively. In an embodiment, the variant Fc region, or FcRn-binding fragment thereof, consists of two Fc domains, both of which comprise amino acids Y, T, E, K, F, and Y at EU positions 252, 254, 256, 433, 434, and 436, respectively.

[0150] In certain embodiments, at least one of the variant Fc domains or FcRn-binding fragments described herein comprises a combination of amino acids selected from the following:

[0151] (i) Q and L at EU positions 250 and 428, respectively;

[0152] (ii) P and A at EU positions 308 and 434, respectively;

[0153] (iii) P and Y at EU positions 308 and 434, respectively;

[0154] (iv) Y, E and Y at EU positions 252, 286 and 434, respectively;

[0155] (v) Y and Y at EU positions 252 and 434, respectively;

[0156] (vi) W and W at EU positions 252 and 434, respectively;

[0157] (vii) Y, Q, A, and Y at EU positions 252, 307, 311, and 434, respectively; or

[0158] (viii) Y, P, and Y at EU positions 252, 308, and 434, respectively.

[0159] In certain embodiments, at least one of the variant Fc domains or FcRn-binding fragments described herein comprises at least one amino acid substitution selected from: G237M; P238A; S239K; K248I; T250A; T250F; T250I; T250M; T250Q; T250S; T250V; T250W; T250Y;52329912564Docket No. ARGX-T2501 / 01 WOM252F; M252W; M252Y; S254T; R255E; T256D; T256E; T256Q; P257A; P257G; P257I; P257L; P257M; P257N; P257S; P257T; P257V; E258H; D265A; D270F; N286A; N286E; T289H; N297A; S298G; V303A; V305A; T307A; T307D; T307F; T307G; T307H; T307I; T307K; T307L; T307M; T307N; T307P; T307Q; T307R; T307S; T307V; T307W; T307Y; V308A; V308F; V308I; V308L; V308M; V308P; V308Q; V308T; V309A; V309D; V309E; V309P; V309R; Q311A; Q311H; Q311I; D312A; D312H; L314K; L314R; N315A; N315H; K317A; N325G; I332V; K334L; K360H; D376A; A378V; E380A; E382A; N384A; G385D; G385H; Q386P; P387E; N389A; N389S; S424A; M428A; M428D; M428F; M428G; M428H; M428I; M428K; M428L; M428N; M428P; M428Q; M428S; M428T; M428V; M428W; M428Y; H433K; N434A; N434F; N434H; N434S; N434W; N434Y; Y436H; Y436I; and Y436F, wherein the positions are defined in accordance with EU numbering. In some embodiments, at least one of the variant Fc domains or FcRn-binding fragments described herein comprises 2, 3, 4 or 5 amino acid substitutions selected from the following: G237M; P238A; S239K; K248I; T250A; T250F; T250I; T250M; T250Q; T250S; T250V; T250W; T250Y; M252F; M252W; M252Y; S254T; R255E; T256D; T256E; T256Q; P257A; P257G; P257I; P257L; P257M; P257N; P257S; P257T; P257V; E258H; D265A; D270F; N286A; N286E; T289H; N297A; S298G; V303A; V305A; T307A; T307D; T307F; T307G; T307H; T307I; T307K; T307L; T307M; T307N; T307P; T307Q; T307R; T307S; T307V; T307W; T307Y; V308A; V308F; V308I; V308L; V308M; V308P; V308Q; V308T; V309A; V309D; V309E; V309P; V309R; Q311A; Q311H; Q311I; D312A; D312H; L314K; L314R; N315A; N315H; K317A; N325G; I332V; K334L; K360H; D376A; A378V; E380A; E382A; N384A; G385D; G385H; Q386P; P387E; N389A; N389S; S424A; M428A; M428D; M428F; M428G; M428H; M428I; M428K; M428L; M428N; M428P; M428Q; M428S; M428T; M428V; M428W; M428Y; H433K; N434A; N434F; N434H; N434S; N434W; N434Y; Y436H; Y436I; and Y436F, wherein the positions are defined in accordance with EU numbering, and wherein any combinations of substitutions are contemplated.

[0160] In certain embodiments, at least one of the variant Fc domains or FcRn-binding fragments described herein comprises a combination of amino acid substitutions selected from the following:

[0161] (i) M252Y, S254T, T256E, H433K, and N434F;

[0162] (ii) T250Q and M428L;

[0163] (iii) V308P and N434A;

[0164] (iv) V308P and N434Y;53329912564Docket No. ARGX-T2501 / 01 WO

[0165] (v) M252Y, V308P, and N434Y;

[0166] (vi) M252Y, N286E, and N434Y;

[0167] (vii) M252Y, S254T, T256E, H433K, N434Y; or

[0168] (viii) M252Y, S254T, T256E, M428L, H433K, or N434F.

[0169] In an embodiment, one, two, or more mutations (e.g., amino acid substitutions) are introduced into the hinge region of a polypeptide described herein, such that the number of cysteine residues in the hinge region is altered (e.g., increased or decreased) as described in, e.g., U.S. Patent No. 5,677,425, herein incorporated by reference in its entirety. The number of cysteine residues in the hinge region may be altered to, e.g., facilitate assembly of the light and heavy chains, or to alter (e.g., increase or decrease) the stability of the polypeptide.

[0170] In an embodiment, one, two, or more amino acid mutations (e.g., substitutions, insertions, or deletions) are introduced into an Fc region, Fc domain, or FcRn-binding fragment thereof to alter (e.g., decrease or increase) half-life of the polypeptide in vivo. See, e.g., International Publication Nos. WO 02 / 060919; WO 98 / 23289; and WO 97 / 34631; and U.S. Patent Nos. 5,869,046, 6,121,022, 6,277,375 and 6,165,745, all of which are herein incorporated by reference in their entireties, for examples of mutations that will alter (e.g., decrease or increase) the half-life of an antibody in vivo. In certain embodiments, one, two, or more amino acid mutations (e.g., substitutions, insertions, or deletions) are introduced into a Fc region, Fc domain, or FcRn-binding fragment thereof to decrease the half-life of the polypeptide in vivo. In other embodiments, one, two, or more amino acid mutations (e.g., substitutions, insertions, or deletions) are introduced into a Fc region, Fc domain, or FcRn-binding fragment thereof to increase the halflife of the antibody in vivo. In an embodiment, the Fc region or Fc domain may have one or more amino acid mutations (e.g., substitutions) in the second constant (CH2) domain (residues 231-340 of human IgGl) and / or the third constant (CH3) domain (residues 341-447 of human IgGl), numbered according to the EU numbering system. In an embodiment, the constant region of the IgGl of a polypeptide described herein comprises a methionine (M) to tyrosine (Y) substitution in position 252, a serine (S) to threonine (T) substitution in position 254, and a threonine (T) to glutamic acid (E) substitution in position 256, numbered according to the EU numbering system. See U.S. Patent No. 7,658,921, which is herein incorporated by reference in its entirety. This type of mutant Fc domain, referred to “as " YTE mutant" has been shown to display fourfold increased half-life as compared to wild-type versions of the same antibody (see Dall'Acqua WF etal., (2006) J Biol Chem 281: 23514-24, which is herein incorporated by reference in its entirety). In an 54329912564Docket No. ARGX-T2501 / 01 WOembodiment, the polypeptide comprises an IgG constant region comprising one, two, three, or more amino acid substitutions of amino acid residues at positions 251-257, 285-290, 308-314, 385-389, and 428-436, numbered according to the EU numbering system.

[0171] In an embodiment, one, two, or more mutations (e.g., amino acid substitutions) are introduced into a Fc region, Fc domain, or FcRn-binding fragment thereof (e.g., a CH2 domain (residues 231-340 of human IgGl) and / or a CH3 domain (residues 341-447 of human IgGl, numbered according to the EU numbering system) and / or a hinge region (residues 216-230, numbered according to the EU numbering system)) of a polypeptide described herein, to increase or decrease the affinity of the antibody for an Fc receptor (e.g., an activated Fc receptor) on the surface of an effector cell. Mutations in the Fc region, Fc domain, or FcRn-binding fragment thereof that decrease or increase the affinity of an antibody for an Fc receptor and techniques for introducing such mutations into the Fc receptor or fragment thereof are known to one of skill in the art. Examples of mutations in the Fc region, Fc domain, or FcRn-binding fragment thereof that can be made to alter the affinity of the variant Fc region, or FcRn-binding fragment thereof for an Fc receptor are described in, e.g., Smith P et al., (2012) PNAS 109: 6181-6186, U.S. Patent No.6,737,056, and International Publication Nos. WO 02 / 060919; WO 98 / 23289; and WO 97 / 34631, all of which are herein incorporated by reference in their entireties.

[0172] In an embodiment, one, two, or more amino acid substitutions are introduced into a Fc region, Fc domain, or FcRn-binding fragment thereof to alter the effector function(s) of the polypeptide. For example, one or more amino acids selected from amino acid residues 234, 235, 236, 237, 239, 243, 267, 292, 297, 300, 318, 320, 322, 328, 330, 332, and 396, numbered according to the EU numbering system, can be replaced with a different amino acid residue such that the polypeptide has an altered affinity for an effector ligand but retains the antigen-binding ability of the parent polypeptide. The effector ligand to which affinity is altered can be, for example, an Fc receptor. This approach is described in further detail in U.S. Patent Nos. 5,624,821 and 5,648,260, each of which is herein incorporated by reference in its entirety. In an embodiment, one or more amino acid substitutions may be introduced into the Fc region or Fc domain of a polypeptide described herein to remove potential glycosylation sites on the Fc region or Fc domain, which may reduce Fc receptor binding (see, e.g., Shields RL etal., (2001) J Biol Chem 276: 6591-604, which is herein incorporated by reference in its entirety). In an embodiment, one or more of the following mutations in the constant region of a polypeptide described herein may be made: an N297A substitution; an N297Q substitution; an L234A substitution; an L234F substitution; an L235A 55329912564Docket No. ARGX-T2501 / 01 WOsubstitution; an L235F substitution; an L235V substitution; an L237A substitution; an S239D substitution; an E233P substitution; an L234V substitution; an L235A substitution; a C236 deletion; a P238A substitution; an S239D substitution; an F243L substitution; a D265A substitution; an S267E substitution; an L328F substitution; an R292P substitution; a Y300L substitution; an A327Q substitution; a P329A substitution; an A330L substitution; an I332E substitution; or a P396L substitution, numbered according to the EU numbering system.

[0173] In an embodiment, a mutation selected from the group consisting of D265A, P329A, and a combination thereof, numbered according to the EU numbering system, may be made in the constant region of a polypeptide described herein. In an embodiment, a mutation selected from the group consisting of L235A, L237A, and a combination thereof, numbered according to the EU numbering system, may be made in the constant region of a polypeptide described herein. In an embodiment, a mutation selected from the group consisting of S267E, L328F, and a combination thereof, numbered according to the EU numbering system, may be made in the constant region of a polypeptide described herein. In an embodiment, a mutation selected from the group consisting of S239D, I332E, optionally A330L, and a combination thereof, numbered according to the EU numbering system, may be made in the constant region of a polypeptide described herein. In an embodiment, a mutation selected from the group consisting of L235V, F243L, R292P, Y300L, P396L, and a combination thereof, numbered according to the EU numbering system, may be made in the constant region of a polypeptide described herein. In an embodiment, a mutation selected from the group consisting of S267E, L328F, and a combination thereof, numbered according to the EU numbering system, may be made in the constant region of a polypeptide described herein.

[0174] In an embodiment, an Fc region, Fc domain, or FcRn-binding fragment thereof described herein comprises the constant region of an IgGl with an N297Q or N297A amino acid substitution, numbered according to the EU numbering system. In an embodiment, an Fc region, Fc domain, or FcRn-binding fragment thereof described herein comprises the constant region of an IgGl with a mutation selected from the group consisting of D265A, P329A, and a combination thereof, numbered according to the EU numbering system. In an embodiment, an Fc region, Fc domain, or FcRn-binding fragment thereof described herein comprises the constant region of an IgGl with a mutation selected from the group consisting of L234A, L235A, and a combination thereof, numbered according to the EU numbering system. In another embodiment, an Fc region, Fc domain, or FcRn-binding fragment thereof described herein comprises the constant region of 56329912564Docket No. ARGX-T2501 / 01 WOan IgGl with a mutation selected from the group consisting of L234F, L235F, N297A, and a combination thereof, numbered according to the EU numbering system. In an embodiment, amino acid residues in the constant region of an Fc region, Fc domain, or FcRn-binding fragment thereof described herein in the positions corresponding to positions L234, L235, and D265 in a human IgGl heavy chain, numbered according to the EU numbering system, are not L, L, and D, respectively. This approach is described in detail in International Publication No. WO 14 / 108483, which is herein incorporated by reference in its entirety. In an embodiment, the amino acids corresponding to positions L234, L235, and D265 in a human IgGl heavy chain are F, E, and A; or A, A, and A, respectively, numbered according to the EU numbering system.

[0175] In an embodiment, the amino acids at positions 433, 434, and 436 of the heavy chain constant region, according to the EU numbering system, are K, F, and Y, respectively. In an embodiment, the amino acids at positions 252, 254, and 256 of the heavy chain constant region, according to the EU numbering system, are Y, T, and E, respectively. In an embodiment, the amino acids at positions 428 and 434 of the heavy chain constant region, according to the EU numbering system, are L and S, respectively. In an embodiment, the amino acid at positions 309, 311, and 434 of the heavy chain constant region, according to the EU numbering system, are D, H, and S, respectively.

[0176] In an embodiment, the polypeptide does not have amino acids Y, T, E, K, and F at EU positions 252, 254, 256, 433, and 434, respectively.

[0177] In an embodiment, one or more amino acids selected from amino acid residues 329, 331, and 322 in the constant region of a polypeptide described herein, numbered according to the EU numbering system, can be replaced with a different amino acid residue such that the antibody has altered Clq binding and / or reduced or abolished complement dependent cytotoxicity (CDC). This approach is described in further detail in U.S. Patent No. 6,194,551 (Idusogie et al.), which is herein incorporated by reference in its entirety. In an embodiment, one or more amino acid residues within amino acid positions 231 to 238 in the N-terminal region of the CH2 domain of a polypeptide described herein are altered to thereby alter the ability of the antibody to fix complement, numbered according to the EU numbering system. This approach is described further in International Publication No. WO 94 / 29351, which is herein incorporated by reference in its entirety. In an embodiment, the Fc region or Fc domain of a polypeptide described herein is modified to increase the ability of the antibody to mediate antibody dependent cellular cytotoxicity (ADCC) and / or to increase the affinity of the polypeptide for an Fc receptor by mutating one or 57329912564Docket No. ARGX-T2501 / 01 WOmore amino acids (e.g., introducing amino acid substitutions) at the following positions: 238, 239, 248, 249, 252, 254, 255, 256, 258, 265, 267, 268, 269, 270, 272, 276, 278, 280, 283, 285, 286, 289, 290, 292, 293, 294, 295, 296, 298, 301, 303, 305, 307, 309, 312, 315, 320, 322, 324, 326, 327, 328, 329, 330, 331, 333, 334, 335, 337, 338, 340, 360, 373, 376, 378, 382, 388, 389, 398, 414, 416, 419, 430, 434, 435, 437, 438, or 439, numbered according to the EU numbering system. This approach is described further in International Publication No. WO 00 / 42072, which is herein incorporated by reference in its entirety.

[0178] In some embodiments, the variant Fc region comprises or consists of two Fc domains in which the first Fc domain comprises amino acid W at EU position 366 and the second Fc domain comprises amino acid S, A, and V at EU positions 366, 368, and 407, respectively. In some embodiments, both Fc domains comprise amino acids Y, T, E, K, F, and Y at EU positions 252, 254, 256, 433, 434, and 436, respectively. In some embodiments, both Fc domains comprise A and A at EU positions 234 and 235, respectively. In some embodiments, both Fc domains comprise amino acids G or A at EU position 329.

[0179] In an embodiment, any of the constant region mutations or modifications described herein can be introduced into one or both heavy chain constant regions of a polypeptide described herein having two heavy chain constant regions. In an embodiment, any of the constant region mutations or modifications described herein can be introduced into the heavy chain constant region of a polypeptide described herein having one heavy chain constant region.

[0180] In an embodiment, the instant disclosure provides a polypeptide comprising one, two or three binding sites for human FcRn, that specifically binds to FcRn and functions as an antagonist.

[0181] In an embodiment, the amino acid sequence of the Fc domains of the variant Fc region comprises or consists of the amino acid sequence of SEQ ID NO: 1. In an embodiment, the amino acid sequence of the Fc domains of the variant Fc region comprises or consists of the amino acid sequence of SEQ ID NO: 2. In an embodiment, the amino acid sequence of the Fc domains of the variant Fc region comprises or consists of the amino acid sequence of SEQ ID NO: 3.

[0182] In an embodiment, the variant Fc region comprises two Fc domains, wherein the amino acid sequence of each of the Fc domains is independently selected from SEQ ID NO: 1, SEQ ID NO: 2, or SEQ ID NO: 3.

[0183] In certain embodiments, the variant Fc region is a heterodimer, where the constituent Fc domains are different from each other. Methods of producing Fc heterodimers are 58329912564Docket No. ARGX-T2501 / 01 WOknown in the art (see, e.g., US 8,216,805, which is incorporated by reference herein in its entirety). In an embodiment, the variant Fc region consists of two Fc domains which form a heterodimer, wherein the amino acid sequence of each of the Fc domains is independently selected from SEQ ID NO: 1, SEQ ID NO: 2, or SEQ ID NO: 3. In an embodiment, the variant Fc region consists of or comprises two Fc domains which form a heterodimer, wherein the amino acid sequence of the first Fc domain consists of or comprises the amino acid sequence of SEQ ID NO: 1, and the amino acid sequence of the second Fc domain consists of or comprises the amino acid sequence of SEQ ID NO: 2 or SEQ ID NO: 3. In an embodiment, the variant Fc region consists of or comprises two Fc domains which form a heterodimer, wherein the amino acid sequence of the first Fc domain consists of or comprises the amino acid sequence of SEQ ID NO: 2, and the amino acid sequence of the second Fc domain consists of or comprises the amino acid sequence of SEQ ID NO: 1 or SEQ ID NO: 3. In an embodiment, the variant Fc region consists of or comprises two Fc domains which form a heterodimer, wherein the amino acid sequence of the first Fc domain consists of or comprises the amino acid sequence of SEQ ID NO: 3, and the amino acid sequence of the second Fc domain consists of or comprises the amino acid sequence of SEQ ID NO: 1 or SEQ ID NO: 2.

[0184] In an embodiment, the variant Fc region consists of or comprises two Fc domains which form a homodimer, wherein the amino acid sequence of each of the Fc domains consists of or comprises the amino acid sequence of SEQ ID NO: 1.

[0185] In an embodiment, the variant Fc region consists of or comprises two Fc domains which form a homodimer, wherein the amino acid sequence of each of the Fc domains consists of or comprises the amino acid sequence of SEQ ID NO: 2.

[0186] In an embodiment, the variant Fc region consists of or comprises two Fc domains which form a homodimer, wherein the amino acid sequence of each of the Fc domains consists of or comprises the amino acid sequence of SEQ ID NO: 3.

[0187] In an embodiment, the variant Fc region comprises or consists of efgartigimod (CAS Registry No. 1821402-21-4). The term “efgartigimod” as used herein is interchangeable with “efgartigimod alfa” and “ARGX-113.” In some embodiments, efgartigimod is efgartigimod alfa-fcab.

[0188] In an embodiment, the variant Fc region is modified to promote heterodimerization. Such modifications are known in the art and any suitable means to promote heterodimerization may be used to generate the IgG-binding molecules described herein. In some embodiments, the variant Fc region comprises one or more mutations of amino acid residues forming the interface 59329912564Docket No. ARGX-T2501 / 01 WOof the CH3 domain of the Fc domains. In some embodiments, the variant Fc region comprises knob-into-hole mutations (see, e.g., Inti. Publ. WO 2006 / 028936, incorporated by reference in its entirety). The mispairing of Ig heavy chains is reduced in this technology by mutating selected amino acids forming the interface of the CH3 domains in IgG. At positions within the CH3 domain at which the two heavy chains interact directly, one or more amino acids with a small side chain (hole) is / are introduced into the sequence of one heavy chain and one or more amino acids with a large side chain (knob) into the counterpart interacting residue location(s) on the other heavy chain. The Fc domains of an Fc region can be composed of immunoglobulin chains of the same subclass (e.g., IgGl or IgG3) or different subclasses (e.g., IgGl and IgG3, or IgG3 and IgG4).

[0189] In some embodiments, the variant Fc region comprises or consists of two Fc domains in which one of the Fc domains comprises amino acid W at EU position 366. In some embodiments, the variant Fc region comprises or consists of two Fc domains in which one of the Fc domains comprises amino acid S, A, and V at EU positions 366, 368, and 407, respectively. In some embodiments, the variant Fc region comprises or consists of two Fc domains in which one Fc domain comprises amino acid W at EU position 366, and the other Fc domain comprises amino acid S, A, and V at EU positions 366, 368, and 407, respectively.

[0190] In some embodiments, the variant Fc region comprises or consists of two Fc domains in which one Fc domain comprises amino acids E and D at EU positions 370 and 409, respectively, and the other Fc domain comprises amino acid K at EU positions 357 and 399. In some embodiments, the variant Fc region comprises or consists of two Fc domains in which one Fc domain comprises amino acids H and A at EU positions 364 and 405, respectively, and the other Fc domain comprises amino acids T and F at EU positions 349 and 394, respectively. In some embodiments, the variant Fc region comprises or consists of two Fc domains in which one Fc domain comprises amino acids V, Y, A, and V at EU positions 350, 351, 405, and 407, respectively, and the other Fc domain comprises amino acids V, L, L, and W at EU positions 350, 366, 392, and 394, respectively. In some embodiments, the variant Fc region comprises or consists of two Fc domains in which one Fc domain comprises amino acids D, M, and A at EU positions 360, 399, and 407, respectively, and the other Fc domain comprises amino acids R, R, V, and V at EU positions 345, 347, 366, and 409, respectively. In some embodiments, the variant Fc region comprises or consists of two Fc domains in which one Fc domain comprises amino acid D at EU positions 409 and 392, and the other Fc domain comprises amino acid K at EU positions 399 and 356. In some embodiments, the variantFc region comprises or consists of two Fc domains in which 60329912564Docket No. ARGX-T2501 / 01 WOone Fc domain comprises amino acids E, W, and C at EU positions 360, 409, and 349, respectively, and the other Fc domain comprises amino acids R, V, T, and C at EU positions 347, 399, 405, and 354, respectively. In some embodiments, the variant Fc region comprises or consists of two Fc domains in which one Fc domain comprises amino acids E and W at EU positions 370 and 409, respectively, and the other Fc domain comprises amino acids N, V, and T at EU positions 357, 399, and 405, respectively.

[0191] In an embodiment, the variant Fc region comprises or consists of two Fc domains which form a heterodimer, wherein the amino acid sequence of the first Fc domain is selected from an amino acid sequence comprising or consisting of SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 16 , SEQ ID NO: 17, SEQ ID NO: 18, SEQ ID NO: 22, SEQ ID NO: 23, and SEQ ID NO: 24 and / or the amino acid sequence of the second Fc domain is selected from an amino acid sequence comprising or consisting of SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 19 , SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 25, SEQ ID NO: 26, and SEQ ID NO: 27. In an embodiment, the variant Fc region comprises or consists of two Fc domains which form a heterodimer, wherein the amino acid sequence of the first Fc domain is selected from an amino acid sequence comprising or consisting of SEQ ID NO: 7, SEQ ID NO: 8, and SEQ ID NO: 9SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 19 , SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 25, SEQ ID NO: 26, and SEQ ID NO: 27 and / or the amino acid sequence of the second Fc domain is selected from an amino acid sequence comprising or consisting of SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 16 , SEQ ID NO: 17, SEQ ID NO: 18, SEQ ID NO: 22, SEQ ID NO: 23, and SEQ ID NO: 24. In an embodiment, the variant Fc region comprises or consists of two Fc domains which form a heterodimer, wherein the amino acid sequence of the first Fc domain comprises or consists of SEQ ID NO: 4 and the amino acid sequence of the second Fc domain comprises or consists of SEQ ID NO: 7. In an embodiment, the variant Fc region comprises or consists of two Fc domains which form a heterodimer, wherein the amino acid sequence of the first Fc domain comprises or consists of SEQ ID NO: 5 and the amino acid sequence of the second Fc domain comprises or consists of SEQ ID NO: 8. In an embodiment, the variant Fc region comprises or consists of two Fc domains which form a heterodimer, wherein the amino acid sequence of the first Fc domain comprises or consists of SEQ ID NO: 6 and the amino acid sequence of the second Fc domain comprises or consists of SEQ ID NO: 9. In an embodiment, the variant Fc region comprises or consists of two Fc domains which form a heterodimer, wherein the amino acid sequence of the first Fc domain comprises or consists of SEQ 61329912564Docket No. ARGX-T2501 / 01 WOID NO: 16 and the amino acid sequence of the second Fc domain comprises or consists of SEQ ID NO: 19. In an embodiment, the variant Fc region comprises or consists of two Fc domains which form a heterodimer, wherein the amino acid sequence of the first Fc domain comprises or consists of SEQ ID NO: 17 and the amino acid sequence of the second Fc domain comprises or consists of SEQ ID NO: 20. In an embodiment, the variant Fc region comprises or consists of two Fc domains which form a heterodimer, wherein the amino acid sequence of the first Fc domain comprises or consists of SEQ ID NO: 18 and the amino acid sequence of the second Fc domain comprises or consists of SEQ ID NO: 21. In an embodiment, the variant Fc region comprises or consists of two Fc domains which form a heterodimer, wherein the amino acid sequence of the first Fc domain comprises or consists of SEQ ID NO: 22 and the amino acid sequence of the second Fc domain comprises or consists of SEQ ID NO: 25. In an embodiment, the variant Fc region comprises or consists of two Fc domains which form a heterodimer, wherein the amino acid sequence of the first Fc domain comprises or consists of SEQ ID NO: 23 and the amino acid sequence of the second Fc domain comprises or consists of SEQ ID NO: 26. In an embodiment, the variant Fc region comprises or consists of two Fc domains which form a heterodimer, wherein the amino acid sequence of the first Fc domain comprises or consists of SEQ ID NO: 24 and the amino acid sequence of the second Fc domain comprises or consists of SEQ ID NO: 27. Tables 6 and 7 provide the amino acid sequences of the Fc domains provided herein.Table 6: Amino acid sequences of Fc domains<<<<<<<<<<<< 62329912564Docket No. ARGX-T2501 / 01 WO<<<<<<<<<<<<<<<<<<<<<<<<<<<63329912564Docket No. ARGX-T2501 / 01 WO<<<<<<<<<<<<<<<<<<<<<<<<<<<64329912564Docket No. ARGX-T2501 / 01 WO<<<<<<<<<<<<<<<Table 7: Consensus amino acid sequences of Fc domains<<<<<<<<65329912564Docket No. ARGX-T2501 / 01 WO<<<<<<<<<<<<

[0192] In some embodiments, the Fc region is a variant Fc region, wherein the variant Fc region comprises or consists of a dimer of a first Fc domain and a second Fc domain, wherein the amino acid sequence of the first and second Fc domain comprises or consists of the amino acid sequence of SEQ ID NO: 28. In some embodiments, the variant Fc region comprises or consists of two Fc domains which form a heterodimer, wherein the amino acid sequence of the first Fc domain comprises or consists of SEQ ID NO: 29 and the amino acid sequence of the second Fc domain comprises or consists of SEQ ID NO: 30. In some embodiments, the variant Fc region comprises or consists of two Fc domains which form a heterodimer, wherein the amino acid sequence of the first Fc domain comprises or consists of SEQ ID NO: 31 and the amino acid sequence of the second Fc domain comprises or consists of SEQ ID NO: 32.IgG-Binding Molecules

[0193] In some embodiments, the IgG-binding molecule comprises only one IgG-binding domain (e.g., a one-armed IgG binding molecule). In some embodiments, the IgG-binding molecule comprises two IgG-binding domains (e.g., a two-armed IgG binding molecule). In some 66329912564Docket No. ARGX-T2501 / 01 WOembodiments, the IgG-binding molecule comprises any Fc region or domain described herein. In some embodiments, the IgG-binding domain is linked to the N-terminus of an Fc domain. In some embodiments, the IgG-binding domain is linked to the C-terminus of an Fc domain.

[0194] In some embodiments, the IgG-binding domain may be linked directly to the N-terminus or the C-terminus of an Fc domain. In some embodiments, the IgG-binding domain is linked to the N-terminus or the C-terminus of an Fc domain via a linker. The linker may be any suitable linker, including those described herein. In some embodiments, the linker is a polypeptide. In some embodiments, the linker is a non-cleavable linker.

[0195] In some embodiments, the IgG-binding molecule comprises a one-armed IgG binding molecule comprising an IgG-binding domain linked to a first Fc domain. In some embodiments, the IgG-binding domain is linked to the N-terminus of the first Fc domain. In some embodiments, the IgG-binding domain is linked to the N-terminus of the first Fc domain by a linker. In some embodiments, the linker is a polypeptide. In some embodiments, the polypeptide comprises a CHI domain. In some embodiments, the one-armed IgG binding molecule comprises a second Fc domain. In some embodiments, the second Fc domain is not linked to an IgG-binding domain. In some embodiments, the IgG binding domain comprises a VH and a VL. In some embodiments, the Fc domains, VH, VL, and linker are any of those described herein.

[0196] In some embodiments, the IgG-binding molecule comprises a one-armed IgG binding molecule comprising an IgG-binding domain linked to second Fc domain. In some embodiments, the IgG-binding domain is linked to the N-terminus of the second Fc domain. In some embodiments, the IgG-binding domain is linked to the N-terminus of the second Fc domain by a linker. In some embodiments, the linker is a polypeptide. In some embodiments, the polypeptide comprises a CHI domain. In some embodiments, the one-armed IgG binding molecule comprises a first Fc domain. In some embodiments, the first Fc domain is not linked to an IgG-binding domain. In some embodiments, the IgG binding domain comprises a VH and a VL. In some embodiments, the Fc domains, VH, VL, and linker are any of those described herein.

[0197] In some embodiments, IgG-binding molecules can comprise a first heavy chain described herein. In some embodiments, the first heavy chain comprises an IgG-binding domain and an Fc domain. In some embodiments, IgG-binding molecules can further comprise a second heavy chain described herein. In some embodiments, the second heavy chain comprises an Fc domain.67329912564Docket No. ARGX-T2501 / 01 WO

[0198] In some embodiments, the first and second heavy chains have the same Fc domain. In some embodiments, the first and second heavy chains have different Fc domains. In some embodiments, the first heavy chain comprises an Fc domain and an IgG-binding domain, while the second heavy chain comprises an Fc domain but does not comprise an IgG-binding domain. In some embodiments, the second heavy chain comprises an Fc domain and an IgG-binding domain, while the first heavy chain comprises an Fc domain but does not comprise an IgG-binding domain.

[0199] In some embodiments, the IgG-binding domain is fused to the N-terminus of the Fc domain. In some embodiments, the IgG-binding domain is fused to the C-terminus of the Fc domain. In some embodiments, the IgG-binding domain is fused to the N-terminus of the Fc domain by a peptide linker. In some embodiments, the IgG-binding domain is fused to the C-terminus of the Fc domain by a peptide linker. In some embodiments, the linker is a CHI domain linker. In some embodiments, the linker comprises an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS GLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSC (SEQ ID NO: 33). In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 33. In some embodiments, the linker consists of the amino acid sequence of SEQ ID NO: 33.

[0200] In some embodiments, the Fc domain comprises an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 1-27. In some embodiments, the Fc domain consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 1-27.

[0201] In some embodiments, the Fc domain comprises the amino acid sequence of any one of SEQ ID NOs: 1-27. In some embodiments, the Fc domain consists of the amino acid sequence of any one of SEQ ID NOs: 1-27.

[0202] In some embodiments, the Fc domain comprises the amino acid sequence of SEQ ID NO: 28, 29, 30, 31, or 32. In some embodiments, the Fc domain consists of the amino acid sequence of SEQ ID NO: 28, 29, 30, 31, or 32.

[0203] In some embodiments, the first and second heavy chains comprise the same Fc domain. In some embodiments, both the first and second heavy chains comprise an Fc domain comprising an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 1-3 and 10-15. In some 68329912564Docket No. ARGX-T2501 / 01 WOembodiments, both the first and second heavy chains comprise an Fc domain consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 1-3 and 10-15. In some embodiments, both the first and second heavy chains comprise an Fc domain comprising the amino acid sequence of any one of SEQ ID NOs: 1-3 and 10-15. In some embodiments, both the first and second heavy chains comprise an Fc domain consisting of the amino acid sequence of any one of SEQ ID NOs: 1-3 and 10-15.

[0204] In some embodiments, the first and second heavy chains comprise different Fc domains. In some embodiments, the first heavy chain comprises an Fc domain comprising an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 4-6, 16-18, or 22-24 and the second heavy chain comprises an Fc domain comprising an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 7-9, 19-21, or 25-27. In some embodiments, the first heavy chain comprises an Fc domain consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 4-6, 16-18, or 22-24 and the second heavy chain comprises an Fc domain consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 7-9, 19-21, or 25-27. In some embodiments, the first heavy chain comprises an Fc domain comprising the amino acid sequence of any one of SEQ ID NOs: 4-6, 16-18, or 22-24 and the second heavy chain comprises an Fc domain comprising the amino acid sequence of any one of SEQ ID NOs: 7-9, 19-21, or 25-27. In some embodiments, when the first heavy chain comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 4 or a variant thereof, the second heavy chain comprises an Fc domain comprising SEQ ID NO: 7 or a variant thereof. In some embodiments, when the first heavy chain comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 5 or a variant thereof, the second heavy chain comprises an Fc domain comprising SEQ ID NO: 8 or a variant thereof. In some embodiments, when the first heavy chain comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 6 or a variant thereof, the second heavy chain comprises an Fc domain comprising SEQ ID NO: 9 or a variant thereof. In some embodiments, when the first heavy chain comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof, the second heavy chain comprises an Fc domain comprising SEQ ID NO: 19 or a variant thereof. In some 69329912564Docket No. ARGX-T2501 / 01 WOembodiments, when the first heavy chain comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 17 or a variant thereof, the second heavy chain comprises an Fc domain comprising SEQ ID NO: 20 or a variant thereof. In some embodiments, when the first heavy chain comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 18 or a variant thereof, the second heavy chain comprises an Fc domain comprising SEQ ID NO: 21 or a variant thereof. In some embodiments, when the first heavy chain comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 22 or a variant thereof, the second heavy chain comprises an Fc domain comprising SEQ ID NO: 25 or a variant thereof. In some embodiments, when the first heavy chain comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 23 or a variant thereof, the second heavy chain comprises an Fc domain comprising SEQ ID NO: 26 or a variant thereof. In some embodiments, when the first heavy chain comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 24 or a variant thereof, the second heavy chain comprises an Fc domain comprising SEQ ID NO: 27 or a variant thereof.

[0205] In some embodiments, the first and / or second heavy chain comprises a VH. In some embodiments, the VH is selected from any IgG-binding domain described herein. In some embodiments, the VH comprises the CDRH1, CDRH2, and CDRH3 of a VH comprising an amino acid sequence selected from SEQ ID NOs: 357-388 and 422-441. In some embodiments, the VH comprises or consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to an amino acid sequence selected from SEQ ID NOs: 357-388 and 422-441. In some embodiments, the VH comprises or consists of an amino acid sequence selected from SEQ ID NOs: 357-388 and 422-441.

[0206] In some embodiments, the IgG-binding molecule comprises a polypeptide comprising or consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 428. In some embodiments, the polypeptide comprises an Fc domain but does not comprise an IgG-binding domain. In some embodiments, the polypeptide comprises or consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 17, 20, 23 or 26. In some embodiments, the polypeptide comprises or consists of the amino acid sequence of any one of SEQ ID NOs: 17, 20, 23 or 26.

[0207] In some embodiments, the IgG-binding molecule comprises an amino acid sequence selected from Table 8 or a variant thereof.70329912564Docket No. ARGX-T2501 / 01 WOTable 8: Exemplary Heavy Chains71329912564Docket No. ARGX-T2501 / 01 WO72329912564Docket No. ARGX-T2501 / 01 WO73329912564Docket No. ARGX-T2501 / 01 WO

[0208] In some embodiments, the IgG-binding molecule comprises an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 34-45. In some embodiments, the IgG-binding molecule comprises the amino acid sequence of any one of SEQ ID NOs: 34-45.

[0209] In some embodiments, the first heavy chain of the IgG-binding molecule comprises or consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 38, 39, 42, and 43 and the second heavy chain of the IgG-binding molecule does not comprise an IgG-binding domain. In some embodiments, the second heavy chain of the IgG-binding molecule comprises an Fc domain but does not comprise an IgG-binding domain. Optionally, the second heavy chain of the IgG-binding molecule comprises or consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 20 or 26.

[0210] In some embodiments, the first heavy chain of the IgG-binding molecule comprises or consists of the amino acid sequence of any one of SEQ ID NOs: 38, 39, 42, and 43 and the second heavy chain of the IgG-binding molecule does not comprise an IgG-binding domain. In some embodiments, the second heavy chain of the IgG-binding molecule comprises an Fc domain but does not comprise an IgG-binding domain. Optionally, the second heavy chain of the IgG-binding molecule comprises or consists of the amino acid sequence of SEQ ID NO: 20 or 26.

[0211] In some embodiments, the first heavy chain of the IgG-binding molecule comprises or consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 40, 41, 44, and 45 and the second heavy chain of the IgG-binding molecule does not comprise an IgG-binding domain. In some embodiments, the second heavy chain of the IgG-binding molecule comprises an Fc domain but does not comprise an IgG-binding domain. Optionally, the second heavy chain of the IgG-binding molecule comprises or consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 17 or 23.

[0212] In some embodiments, the first heavy chain of the IgG-binding molecule comprises or consists of the amino acid sequence of any one of SEQ ID NOs: 40, 41, 44, and 45 and the second heavy chain of the IgG-binding molecule does not comprise an IgG-binding domain. In some embodiments, the second heavy chain of the IgG-binding molecule comprises an Fc domain 74329912564Docket No. ARGX-T2501 / 01 WObut does not comprise an IgG-binding domain. Optionally, the second heavy chain of the IgG-binding molecule comprises or consists of the amino acid sequence of SEQ ID NO: 17 or 23.

[0213] In some embodiments, the first heavy chain of the IgG-binding molecule comprises an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 38 and the second heavy chain of the IgG-binding molecule comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 20, but does not comprise an IgG-binding domain. In some embodiments, the first heavy chain of the IgG-binding molecule consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 38 and the second heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 20.

[0214] In some embodiments, the first heavy chain of the IgG-binding molecule comprises the amino acid sequence of SEQ ID NO: 38 and the second heavy chain of the IgG-binding molecule comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 20 but does not comprise an IgG-binding domain. In some embodiments, the first heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 38 and the second heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 20.

[0215] In some embodiments, the first heavy chain of the IgG-binding molecule comprises an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 39 and the second heavy chain of the IgG-binding molecule comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 20, but does not comprise an IgG-binding domain. In some embodiments, the first heavy chain of the IgG-binding molecule consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 39 and the second heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 20.

[0216] In some embodiments, the first heavy chain of the IgG-binding molecule comprises the amino acid sequence of SEQ ID NO: 39 and the second heavy chain of the IgG-binding molecule comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 20 but does not comprise an IgG-binding domain. In some embodiments, the first heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 39 and the second heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 20.75329912564Docket No. ARGX-T2501 / 01 WO

[0217] In some embodiments, the first heavy chain of the IgG-binding molecule comprises an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 42 and the second heavy chain of the IgG-binding molecule comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 20, but does not comprise an IgG-binding domain. In some embodiments, the first heavy chain of the IgG-binding molecule consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 42 and the second heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 20.

[0218] In some embodiments, the first heavy chain of the IgG-binding molecule comprises the amino acid sequence of SEQ ID NO: 42 and the second heavy chain of the IgG-binding molecule comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 20 but does not comprise an IgG-binding domain. In some embodiments, the first heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 42 and the second heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 20.

[0219] In some embodiments, the first heavy chain of the IgG-binding molecule comprises an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 43 and the second heavy chain of the IgG-binding molecule comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 20, but does not comprise an IgG-binding domain. In some embodiments, the first heavy chain of the IgG-binding molecule consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 43 and the second heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 20.

[0220] In some embodiments, the first heavy chain of the IgG-binding molecule comprises the amino acid sequence of SEQ ID NO: 43 and the second heavy chain of the IgG-binding molecule comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 20 but does not comprise an IgG-binding domain. In some embodiments, the first heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 43 and the second heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 20.

[0221] In some embodiments, the first heavy chain of the IgG-binding molecule comprises an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99%76329912564Docket No. ARGX-T2501 / 01 WOidentical to the amino acid sequence of SEQ ID NO: 40 and the second heavy chain of the IgG-binding molecule comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 17, but does not comprise an IgG-binding domain. In some embodiments, the first heavy chain of the IgG-binding molecule consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 40 and the second heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 17.

[0222] In some embodiments, the first heavy chain of the IgG-binding molecule comprises the amino acid sequence of SEQ ID NO: 40 and the second heavy chain of the IgG-binding molecule comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 17 but does not comprise an IgG-binding domain. In some embodiments, the first heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 40 and the second heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 17.

[0223] In some embodiments, the first heavy chain of the IgG-binding molecule comprises an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 41 and the second heavy chain of the IgG-binding molecule comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 17, but does not comprise an IgG-binding domain. In some embodiments, the first heavy chain of the IgG-binding molecule consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 41 and the second heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 17.

[0224] In some embodiments, the first heavy chain of the IgG-binding molecule comprises the amino acid sequence of SEQ ID NO: 41 and the second heavy chain of the IgG-binding molecule comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 17 but does not comprise an IgG-binding domain. In some embodiments, the first heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 41 and the second heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 17.

[0225] In some embodiments, the first heavy chain of the IgG-binding molecule comprises an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 44 and the second heavy chain of the IgG-binding molecule comprises an Fc domain comprising the amino acid sequence of SEQ ID NO:77329912564Docket No. ARGX-T2501 / 01 WO17, but does not comprise an IgG-binding domain. In some embodiments, the first heavy chain of the IgG-binding molecule consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 44 and the second heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 17.

[0226] In some embodiments, the first heavy chain of the IgG-binding molecule comprises the amino acid sequence of SEQ ID NO: 44 and the second heavy chain of the IgG-binding molecule comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 17 but does not comprise an IgG-binding domain. In some embodiments, the first heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 44 and the second heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 17.

[0227] In some embodiments, the first heavy chain of the IgG-binding molecule comprises an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 45 and the second heavy chain of the IgG-binding molecule comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 17, but does not comprise an IgG-binding domain. In some embodiments, the first heavy chain of the IgG-binding molecule consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 45 and the second heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 17.

[0228] In some embodiments, the first heavy chain of the IgG-binding molecule comprises the amino acid sequence of SEQ ID NO: 45 and the second heavy chain of the IgG-binding molecule comprises an Fc domain comprising the amino acid sequence of SEQ ID NO: 17 but does not comprise an IgG-binding domain. In some embodiments, the first heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 45 and the second heavy chain of the IgG-binding molecule consists of the amino acid sequence of SEQ ID NO: 17.

[0229] In some embodiments, the IgG-binding molecule further comprises a light chain. In some embodiments, the light chain comprises a VL. In some embodiments, the VL is selected from any IgG-binding domain described herein. In some embodiments, the VL comprises the CDRL1, CDRL2, and CDRL3 of a VL comprising an amino acid sequence selected from SEQ ID NOs: 389-420 and 443-453. In some embodiments, the VL comprises or consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to an amino 78329912564Docket No. ARGX-T2501 / 01 WOacid sequence selected from SEQ ID NOs: 389-420 and 443-453. In some embodiments, the VL comprises or consists of an amino acid sequence selected from SEQ ID NOs: 389-420 and 443-453.

[0230] In some embodiments, the IgG-binding molecule comprises a first polypeptide, a second polypeptide and a third polypeptide, wherein the first polypeptide comprises an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 428, the second polypeptide comprises an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 451, and the third polypeptide comprises an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 20. In some embodiments, the first polypeptide further comprises an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 17.

[0231] In some embodiments, the IgG-binding molecule comprises a first polypeptide, a second polypeptide and a third polypeptide, wherein the first polypeptide comprises the amino acid sequence of SEQ ID NO: 428, the second polypeptide comprises or consists of the amino acid sequence of SEQ ID NO: 451, and the third polypeptide comprises the amino acid sequence of SEQ ID NO: 20. In some embodiments, the first polypeptide further comprises the amino acid sequence of SEQ ID NO: 17.

[0232] In some embodiments, the light chain further comprises a constant domain. In some embodiments, the light chain constant domain comprises a kappa chain constant domain. In some embodiments, the light chain constant domain comprises a lambda chain constant domain.

[0233] In some embodiments, the lambda chain constant domain comprises or consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of GQPKAAPSVTLFPPSSEELQANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPS KQSNNKYAASSYLSLTPEQWKSHRSYSCQVTHEGSTVEKTVAPTECS (SEQ ID NO: 46). In some embodiments, the lambda chain constant domain comprises or consists of the amino acid sequence of SEQ ID NO: 46.

[0234] In some embodiments, the IgG-binding molecule comprises an amino acid sequence selected from Table 9 or a variant thereof.79329912564Docket No. ARGX-T2501 / 01 WOTable 9: Exemplary Light Chains80329912564Docket No. ARGX-T2501 / 01 WO81329912564Docket No. ARGX-T2501 / 01 WO

[0235] In some embodiments, the IgG-binding molecule comprises a light chain comprising or consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 47-58. In some embodiments, the IgG-binding molecule comprises a light chain comprising or consisting of the amino acid sequence of any one of SEQ ID NOs: 47-58.

[0236] In some embodiments, the IgG-binding molecule comprises a first heavy chain, a second heavy chain and a light chain. In some embodiments, the first heavy chain of the IgG-binding molecule comprises or consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 34-45 and the second heavy chain of the IgG-binding molecule does not comprise an IgG-binding domain. In some embodiments, the second heavy chain of the IgG-binding molecule comprises an Fc domain but does not comprise an IgG-binding domain. In some embodiments, the second heavy chain of the IgG-binding molecule comprises or consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 17, 20, 23, or 26. In some embodiments, the light chain comprises or consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 47-58.

[0237] In some embodiments, the first heavy chain of the IgG-binding molecule comprises or consists of the amino acid sequence of any one of SEQ ID NOs: 34-45 and the second heavy chain of the IgG-binding molecule does not comprise an IgG-binding domain. In some embodiments, the second heavy chain of the IgG-binding molecule comprises an Fc domain but does not comprise an IgG-binding domain. In some embodiments, the second heavy chain of the IgG-binding molecule comprises or consists of the amino acid sequence of SEQ ID NO: 17, 20, 23, or 26. In some embodiments, the light chain comprises or consists of the amino acid sequence of any one of SEQ ID NOs: 47-58.

[0238] In some embodiments, the first heavy chain, the second heavy chain, and the light chain comprise or consist of amino acid sequences at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequences of SEQ ID NOs: 38, 20, and 47; 38, 20, and 48; 38, 20, and 49; 38, 20, and 50; 38, 20, and 51; 38, 20, and 52; 38, 20, and 53; 38, 20, and 54; 38, 20, and 55; 38, 20, and 56; 38, 20, and 57; 38, 20, and 58; 38, 26, and 47; 38, 26, and 48; 38, 26, and 49; 38, 26, and 50; 38, 26, and 51; 38, 26, and 52; 38, 26, and 53; 38, 26, and 54; 38, 26, and 55; 38, 26, and 56; 38, 26, and 57; 38, 26, and 58; 39, 20, and 47; 39, 20, and 48;82329912564Docket No. ARGX-T2501 / 01 WO39, 20, and 49; 39, 20, and 50; 39, 20, and 51; 39, 20, and 52; 39, 20, and 53; 39, 20, and 54; 39, 20, and 55; 39, 20, and 56; 39, 20, and 57; 39, 20, and 58; 39, 26, and 47; 39, 26, and 48; 39, 26, and 49; 39, 26, and 50; 39, 26, and 51; 39, 26, and 52; 39, 26, and 53; 39, 26, and 54; 39, 26, and 55; 39, 26, and 56; 39, 26, and 57; 39, 26, and 58; 42, 20, and 47; 42, 20, and 48; 42, 20, and 49; 42, 20, and 50; 42, 20, and 51; 42, 20, and 52; 42, 20, and 53; 42, 20, and 54; 42, 20, and 55; 42, 20, and 56; 42, 20, and 57; 42, 20, and 58; 42, 26, and 47; 42, 26, and 48; 42, 26, and 49; 42, 26, and 50; 42, 26, and 51; 42, 26, and 52; 42, 26, and 53; 42, 26, and 54; 42, 26, and 55; 42, 26, and 56; 42, 26, and 57; 42, 26, and 58; 43, 20, and 47; 43, 20, and 48; 43, 20, and 49; 43, 20, and 50; 43, 20, and 51; 43, 20, and 52; 43, 20, and 53; 43, 20, and 54; 43, 20, and 55; 43, 20, and 56; 43, 20, and 57; 43, 20, and 58; 43, 26, and 47; 43, 26, and 48; 43, 26, and 49; 43, 26, and 50; 43, 26, and 51; 43, 26, and 52; 43, 26, and 53; 43, 26, and 54; 43, 26, and 55; 43, 26, and 56; 43, 26, and 57; 43, 26, and 58, 40, 17, and 47; 40, 17, and 48; 40, 17, and 49; 40, 17, and 50; 40, 17, and 51; 40, 17, and 52; 40, 17, and 53; 40, 17, and 54; 40, 17, and 55; 40, 17, and 56; 40, 17, and 57; 40, 17, and 58; 40, 23, and 47; 40, 23, and 48; 40, 23, and 49; 40, 23, and 50; 40, 23, and 51; 40, 23, and 52; 40, 23, and 53; 40, 23, and 54; 40, 23, and 55; 40, 23, and 56; 40, 23, and 57; 40, 23, and 58; 41, 17, and 47; 41, 17, and 48; 41, 17, and 49; 41, 17, and 50; 41, 17, and 51; 41, 17, and 52; 41, 17, and 53; 41, 17, and 54; 41, 17, and 55; 41, 17, and 56; 41, 17, and 57; 41, 17, and 58; 41, 23, and 47; 41, 23, and 48; 41, 23, and 49; 41, 23, and 50; 41, 23, and 51; 41, 23, and 52; 41, 23, and 53; 41, 23, and 54; 41, 23, and 55; 41, 23, and 56; 41, 23, and 57; 41, 23, and 58; 44, 17, and 47; 44, 17, and 48; 44, 17, and 49; 44, 17, and 50; 44, 17, and 51; 44, 17, and 52; 44, 17, and 53; 44, 17, and 54; 44, 17, and 55; 44, 17, and 56; 44, 17, and 57; 44, 17, and 58; 44, 23, and 47; 44, 23, and 48; 44, 23, and 49; 44, 23, and 50; 44, 23, and 51; 44, 23, and 52; 44, 23, and 53; 44, 23, and 54; 44, 23, and 55; 44, 23, and 56; 44, 23, and 57; 44, 23, and 58; 45, 17, and 47; 45, 17, and 48; 45, 17, and 49; 45, 17, and 50; 45, 17, and 51; 45, 17, and 52; 45, 17, and 53; 45, 17, and 54; 45, 17, and 55; 45, 17, and 56; 45, 17, and 57; 45, 17, and 58; 45, 23, and 47; 45, 23, and 48; 45, 23, and 49; 45, 23, and 50; 45, 23, and 51; 45, 23, and 52; 45, 23, and 53; 45, 23, and 54; 45, 23, and 55; 45, 23, and 56; 45, 23, and 57; or 45, 23, and 58, respectively.Polynucleotides, Vectors, and Methods of Production

[0239] The disclosure also provides polynucleotides encoding the IgG-binding molecules disclosed herein or fragments thereof. In some embodiments, the polynucleotide encodes an IgG-binding domain of the disclosure. In some embodiments, the polynucleotide encodes an IgG- 83329912564Docket No. ARGX-T2501 / 01 WObinding molecule of the disclosure. In some embodiments, the polynucleotide encodes an Fc region of the disclosure. In some embodiments, the polynucleotide encodes an Fc domain of the disclosure. In some embodiments, the polynucleotide encodes one or more of an IgG-binding domain, an Fc domain, and a linker. In some embodiments, the polynucleotide encodes an IgG-binding domain and an Fc domain, and optionally a linker. In some embodiments, the polynucleotide encodes one or more of an IgG-binding domain, an Fc region, and a linker. In some embodiments, the polynucleotide encodes an IgG-binding domain and an Fc region, and optionally a linker. In some embodiments, the polynucleotide encodes one or more of an IgG-binding domain, an Fc domain, and a linker. In some embodiments, the polynucleotide encodes an IgG-binding molecule comprising a first heavy chain comprising an IgG-binding domain and an Fc domain, and optionally a linker. In some embodiments, the polynucleotide encodes an IgG-binding molecule comprising a second heavy chain comprising an Fc domain and not comprising an IgG-binding domain. In some embodiments, the polynucleotide encodes an IgG-binding molecule comprising a light chain.

[0240] As used herein, an “isolated” polynucleotide or nucleic acid molecule is one which is separated from other nucleic acid molecules which are present in the natural source (e.g., in a mouse or a human) of the nucleic acid molecule. Moreover, an “isolated” nucleic acid molecule, such as a cDNA molecule, can be substantially free of other cellular material, or culture medium when produced by recombinant techniques, or substantially free of chemical precursors or other chemicals when chemically synthesized. For example, the language “substantially free” includes preparations of polynucleotide or nucleic acid molecules having less than about 15%, 10%, 5%, 2%, 1%, 0.5%, or 0.1% (in particular, less than about 10%) of other material, e.g., cellular material, culture medium, other nucleic acid molecules, chemical precursors and / or other chemicals. In an embodiment, a nucleic acid molecule(s) encoding a polypeptide described herein is isolated or purified.

[0241] In an aspect, provided herein are polynucleotides comprising a nucleotide sequence encoding an IgG-binding molecule described herein. In another aspect, provided herein are polynucleotides comprising a nucleotide sequence encoding an IgG-binding domain described herein. In another aspect, provided herein are polynucleotides comprising a nucleotide sequence encoding an Fc domain described herein. In another aspect, provided herein are polynucleotides comprising a nucleotide sequence encoding a linker described herein.84329912564Docket No. ARGX-T2501 / 01 WO

[0242] The polynucleotides can comprise nucleotide sequences encoding an sdAb (e.g., a VHH), a Fab fragment, an scFv, a VH, or a VL comprising FRs and CDRs of IgG-binding domains described herein. The polynucleotides can also comprise nucleotide sequences encoding an antibody mimetic as described herein. In some embodiments, the polynucleotides can comprise nucleotide sequences encoding a VHH comprising FR and CDRs of IgG-binding domains described herein. In some embodiments, the polynucleotides can comprise nucleotide sequences encoding a heavy chain comprising VHH FRs and CDRs of IgG-binding domains described herein and / or an Fc domain as described herein.

[0243] In some embodiments, the polynucleotides can comprise nucleotide sequences encoding a first heavy chain described herein. In some embodiments, the first heavy chain comprises an Fc domain and an IgG-binding domain joined by a linker. In some embodiments, polynucleotides can comprise nucleotide sequences encoding a second heavy chain described herein. In some embodiments, the second heavy chain comprises an Fc domain but not an IgG-binding domain e.g., another IgG-binding domain). In some embodiments, the first and second heavy chains are the same. In some embodiments, the first and second heavy chains are different.

[0244] In some embodiments, the first and second heavy chains have the same Fc domain. In some embodiments, the first and second heavy chains have different Fc domains. In some embodiments, the first and second heavy chains both comprise an IgG-binding domain. In some embodiments, the IgG-binding domains on the first and second heavy chains are the same. In some embodiments, the IgG-binding domains on the first and second heavy chains are different. In some embodiments, the second heavy chain comprises an Fc domain but does not comprise an IgG-binding domain, while the first heavy chain comprises an Fc domain and an IgG-binding domain. In some embodiments, the second heavy chain comprises an Fc domain but does not comprise an IgG-binding domain or a linker, while the first heavy chain comprises an Fc domain and an IgG-binding domain. In some embodiments, the second heavy chain comprises an Fc domain but does not comprise an IgG-binding domain or a linker, while the first heavy chain comprises an Fc domain and an IgG-binding domain and a linker.

[0245] In some embodiments, the polynucleotides comprise or consist of a nucleotide sequence that encodes an Fc domain comprising or consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 1-27. In some embodiments, the polynucleotides comprise or consist of a nucleotide sequence that encodes an Fc domain comprising or consisting of the amino acid 85329912564Docket No. ARGX-T2501 / 01 WOsequence of any one of SEQ ID NOs: 1-27. In some embodiments, the polynucleotides comprise or consist of a nucleotide sequence that encodes an Fc domain comprising or consisting of the amino acid sequence of SEQ ID NOs: 28-32.

[0246] In some embodiments, the polynucleotides comprise nucleotide sequences that encode two or more Fc domains. In some embodiments, the polynucleotides comprise nucleotide sequences that encode two Fc domains. In some embodiments, the polynucleotides comprise a first nucleotide sequence that encodes a first Fc domain and a second nucleotide sequence that encodes a second Fc domain. In some embodiments, the first nucleotide sequence and the second nucleotide sequence are comprised in distinct nucleic acid molecules. In some embodiments, the first nucleotide sequence and the second nucleotide sequence are comprised in the same nucleic acid molecule.

[0247] In some embodiments, the first and second nucleotide sequence encode the same Fc domain. In some embodiments, both the first and second nucleotide sequence encode an Fc domain comprising or consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 1-3. In some embodiments, both the first and second nucleotide sequence encode an Fc domain comprising or consisting of the amino acid sequence of any one of SEQ ID NOs: 1-3. In some embodiments, both the first and second nucleotide sequence encode an Fc domain comprising or consisting of the amino acid sequence of SEQ ID NO: 10.

[0248] In some embodiments, the first and second nucleotide sequence encode different Fc domains. In some embodiments, the first nucleotide sequence encodes an Fc domain comprising or consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 4-6, 16-18, and 22-24 and the second nucleotide sequence encodes an Fc domain comprising or consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 7-9, 19-21, and 25-27. In some embodiments, the first nucleotide sequence encodes an Fc domain comprising or consisting of the amino acid sequence of any one of SEQ ID NOs: 4-6, 16-18, and 22-24 and the second nucleotide sequence encodes an Fc domain comprising or consisting of the amino acid sequence of any one of SEQ ID NOs: 7-9, 19-21, and 25-27. In some embodiments, when the first nucleotide sequence encodes the amino acid sequence of SEQ ID NO: 4 or a variant thereof, the second nucleotide sequence encodes SEQ ID NO: 7 or a variant thereof. In some embodiments, when the first nucleotide 86329912564Docket No. ARGX-T2501 / 01 WOsequence encodes the amino acid sequence of SEQ ID NO: 5 or a variant thereof, the second nucleotide sequence encodes SEQ ID NO: 8 or a variant thereof. In some embodiments, when the first nucleotide sequence encodes the amino acid sequence of SEQ ID NO: 6 or a variant thereof, the second nucleotide sequence encodes SEQ ID NO: 9 or a variant thereof. In some embodiments, when the first nucleotide sequence encodes the amino acid sequence of SEQ ID NO: 16 or a variant thereof, the second nucleotide sequence encodes SEQ ID NO: 19 or a variant thereof. In some embodiments, when the first nucleotide sequence encodes the amino acid sequence of SEQ ID NO: 17 or a variant thereof, the second nucleotide sequence encodes SEQ ID NO: 20 or a variant thereof. In some embodiments, when the first nucleotide sequence encodes the amino acid sequence of SEQ ID NO: 18 or a variant thereof, the second nucleotide sequence encodes SEQ ID NO: 21 or a variant thereof. In some embodiments, when the first nucleotide sequence encodes the amino acid sequence of SEQ ID NO: 22 or a variant thereof, the second nucleotide sequence encodes SEQ ID NO: 25 or a variant thereof. In some embodiments, when the first nucleotide sequence encodes the amino acid sequence of SEQ ID NO: 23 or a variant thereof, the second nucleotide sequence encodes SEQ ID NO: 26 or a variant thereof. In some embodiments, when the first nucleotide sequence encodes the amino acid sequence of SEQ ID NO: 24 or a variant thereof, the second nucleotide sequence encodes SEQ ID NO: 27 or a variant thereof.

[0249] In some embodiments, the first and / or second nucleotide sequence also encode an IgG-binding domain. In some embodiments, the first and second nucleotide sequence encode the same IgG-binding domain. In some embodiments, the first and second nucleotide sequence encode different IgG-binding domains. In some embodiments, the first nucleotide sequence encodes an Fc domain and an IgG-binding domain and the second nucleotide sequence encodes an Fc domain but no IgG-binding domain. The IgG-binding domains encoded by the first and / or second nucleotide sequences can be any described herein.

[0250] In some embodiments, the first and / or second nucleotide sequence also encode a peptide linker. In some embodiments, the first and second nucleotide sequence encode the same peptide linker. In some embodiments, the first and second nucleotide sequence encode different peptide linkers. In some embodiments, the first nucleotide sequence encodes an Fc domain, a peptide linker, and an IgG-binding domain and the second nucleotide sequence encodes an Fc domain but no peptide linker or IgG-binding domain. In some embodiments, the first nucleotide sequence encodes an IgG-binding domain, a peptide linker, and an Fc domain and the second nucleotide sequence encodes an Fc domain but no peptide linker or IgG-binding domain. The 87329912564Docket No. ARGX-T2501 / 01 WOpeptide linkers encoded by the first and / or second nucleotide sequences can be any described herein. In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 33.

[0251] In some embodiments, the polynucleotide comprises a nucleotide sequence that encodes a protein comprising or consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ IDNOs: 34-45.

[0252] In some embodiments, the polynucleotide comprises a nucleotide sequence that encodes a protein comprising or consisting of the amino acid sequence of any one of SEQ ID NOs: 34-45.

[0253] In some embodiments, the first nucleotide sequence encodes a protein comprising or consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 38, 39, 42, and 43 and the second nucleotide sequence encodes an Fc domain but does not encode an IgG-binding domain. Optionally, the second nucleotide sequence encodes a protein comprising or consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 20 or 26.

[0254] In some embodiments, the first nucleotide sequence encodes a protein comprising or consisting of the amino acid sequence of any one of SEQ ID NOs: 38, 39, 42, and 43 and the second nucleotide sequence encodes an Fc domain but does not encode an IgG-binding domain. Optionally, the second nucleotide sequence encodes a protein comprising or consisting of the amino acid sequence of SEQ ID NO: 20 or 26.

[0255] In some embodiments, the first nucleotide sequence encodes a protein comprising or consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 40, 41, 44, and 45 and the second nucleotide sequence encodes an Fc domain but does not encode an IgG-binding domain. Optionally, the second nucleotide sequence encodes a protein comprising or consisting of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 17 or 23.

[0256] In some embodiments, the first nucleotide sequence encodes a protein comprising or consisting of the amino acid sequence of any one of SEQ ID NOs: 40, 41, 44, and 45 and the second nucleotide sequence encodes an Fc domain but does not encode an IgG-binding domain.88329912564Docket No. ARGX-T2501 / 01 WOOptionally, the second nucleotide sequence encodes a protein comprising or consisting of the amino acid sequence of SEQ ID NO: 17 or 23.

[0257] In some embodiments, the polynucleotide comprises a nucleotide sequence that encodes a first heavy chain, a second heavy chain and a light chain. In some embodiments, the first heavy chain of the IgG-binding molecule comprises or consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 34-45 and the second heavy chain of the IgG-binding molecule does not comprise an IgG-binding domain. In some embodiments, the second heavy chain of the IgG-binding molecule comprises an Fc domain but does not comprise an IgG-binding domain. In some embodiments, the second heavy chain of the IgG-binding molecule comprises or consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 17, 20, 23, or 26. In some embodiments, the second heavy chain of the IgG-binding molecule comprises or consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 17, 20, 23, or 26. In some embodiments, the light chain comprises or consists of an amino acid sequence at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of any one of SEQ ID NOs: 47-58.

[0258] In some embodiments, the polynucleotide comprises a nucleotide sequence that encodes an amino acid sequence that comprises or consists of the amino acid sequence of any one of SEQ ID NOs: 34-45; an amino acid sequence that comprises or consists of SEQ ID NOs: 17, 20, 23, or 26 and / or an amino acid sequence of any one of SEQ ID NOs: 47-58.

[0259] Also provided herein are polynucleotides encoding a polypeptide as provided above that are optimized, e.g., by codon / RNA optimization, replacement with heterologous signal sequences, and elimination of mRNA instability elements. Methods to generate optimized nucleic acids for recombinant expression by introducing codon changes and / or eliminating inhibitory regions in the mRNA can be carried out by adapting the optimization methods described in, e.g., U.S. Patent Nos. 5,965,726; 6,174,666; 6,291,664; 6,414,132; and 6,794,498, accordingly, all of which are herein incorporated by reference in their entireties. For example, potential splice sites and instability elements (e.g., A / T or A / U rich elements) within the RNA can be mutated without altering the amino acids encoded by the nucleic acid sequences to increase stability of the RNA for recombinant expression. The alterations utilize the degeneracy of the genetic code, e.g., using an alternative codon for an identical amino acid. In an embodiment, it can be desirable to alter one 89329912564Docket No. ARGX-T2501 / 01 WOor more codons to encode a conservative mutation, e.g., a similar amino acid with similar chemical structure and properties and / or function as the original amino acid.

[0260] The polynucleotides can be obtained, and the nucleotide sequence of the polynucleotides determined, by any method known in the art. Nucleotide sequences encoding proteins described herein, and modified versions of these antibodies can be determined using methods well known in the art, i.e., nucleotide codons known to encode particular amino acids are assembled in such a way to generate a nucleic acid that encodes the protein. Such a polynucleotide encoding the protein can be assembled from chemically synthesized oligonucleotides (e.g., as described in Kutmeier G et al., (1994) BioTechniques 17: 242-6, herein incorporated by reference in its entirety), which, briefly, involves the synthesis of overlapping oligonucleotides containing portions of the sequence encoding the antibody, annealing, and ligating of those oligonucleotides, and then amplification of the ligated oligonucleotides by PCR.

[0261] Alternatively, a polynucleotide encoding a protein described herein can be generated from nucleic acid from a suitable source (e.g., a hybridoma) using methods well known in the art (e.g., PCR and other molecular cloning methods). For example, PCR amplification using synthetic primers hybridizable to the 3' and 5' ends of a known sequence can be performed using genomic DNA obtained from hybridoma cells producing the polypeptide of interest. Such PCR amplification methods can be used to obtain nucleic acids comprising the sequence encoding the polypeptide. The amplified nucleic acids can be cloned into vectors for expression in host cells and for further cloning.

[0262] If a clone containing a nucleic acid encoding a particular polypeptide is not available, but the sequence of the polypeptide is known, a nucleic acid encoding the polypeptide can be chemically synthesized or obtained from a suitable source (e.g., a cDNA library generated from, or nucleic acid, preferably poly A+ RNA, isolated from any tissue or cells expressing the polypeptide described herein) by PCR amplification using synthetic primers hybridizable to the 3' and 5' ends of the sequence or by cloning using an oligonucleotide probe specific for the particular gene sequence to identify, e.g., a cDNA clone from a cDNA library that encodes the polypeptide. Amplified nucleic acids generated by PCR can then be cloned into replicable cloning vectors using any method well known in the art.

[0263] DNA encoding proteins described herein can be readily isolated and sequenced using conventional procedures. Hybridoma cells can serve as a source of such DNA. Once isolated, the DNA can be placed into expression vectors, which are then transfected into host cells such as 90329912564Docket No. ARGX-T2501 / 01 WOE. coli cells, simian COS cells, Chinese hamster ovary (CHO) cells (e.g, CHO cells from the CHO GS System™ (Lonza)), or myeloma cells that do not otherwise produce the proteins described herein.

[0264] Also provided are polynucleotides that hybridize under high stringency, intermediate or lower stringency hybridization conditions to polynucleotides that encode a protein described herein.

[0265] Hybridization conditions have been described in the art and are known to one of skill in the art. For example, hybridization under stringent conditions can involve hybridization to filter-bound DNA in 6x sodium chloride / sodium citrate (SSC) at about 45° C followed by one or more washes in 0.2xSSC / 0.1% SDS at about 50-65° C; hybridization under highly stringent conditions can involve hybridization to filter-bound nucleic acid in 6xSSC at about 45° C followed by one or more washes in 0. lxSSC / 0.2% SDS at about 68° C. Hybridization under other stringent hybridization conditions is known to those of skill in the art and has been described, see, e.g., Ausubel FM etal., eds., (1989) Current Protocols in Molecular Biology, Vol. I, Green Publishing Associates, Inc. and John Wiley & Sons, Inc., New York at pages 6.3.1-6.3.6 and 2.10.3, which is herein incorporated by reference in its entirety.

[0266] In an aspect, provided herein are cells (e.g., host cells) expressing (e.g., recombinantly) a protein described herein, and related polynucleotides and expression vectors. Provided herein are vectors (e.g., expression vectors) comprising polynucleotides comprising nucleotide sequences encoding a protein described herein for recombinant expression in host cells, preferably in mammalian cells (e.g., CHO cells). Also provided herein are host cells comprising such vectors for recombinantly expressing proteins described herein. In an aspect, provided herein are methods for producing a protein described herein, comprising expressing the polypeptide from a host cell.

[0267] Recombinant expression of a protein described herein generally involves construction of an expression vector containing a polynucleotide that encodes the polypeptide. Once a polynucleotide encoding a polypeptide described herein has been obtained, the vector for the production of the polypeptide can be produced by recombinant DNA technology using techniques well known in the art. Thus, methods for preparing a protein by expressing a polynucleotide containing a polypeptide encoding nucleotide sequence are described herein. Methods which are well known to those skilled in the art can be used to construct expression vectors containing polypeptide coding sequences and appropriate transcriptional and translational 91329912564Docket No. ARGX-T2501 / 01 WOcontrol signals. These methods include, for example, in vitro recombinant DNA techniques, synthetic techniques, and in vivo genetic recombination. Also provided are replicable vectors comprising a nucleotide sequence encoding containing a polypeptide described herein, operably linked to a promoter. Such vectors can, for example, include a nucleotide sequence encoding a first heavy chain of the disclosure (see, e.g., International Publication Nos. WO 86 / 05807 and WO 89 / 01036; and U.S. Patent No. 5,122,464, which are herein incorporated by reference in their entireties), and a second heavy chain of the disclosure can be cloned into such a vector for expression of the first heavy chain, the second heavy chain, or both the first and second heavy chains.

[0268] In an embodiment, a vector comprises a polynucleotide encoding an sdAb, Fab fragment, scFv, VHH, VH, VL, heavy chain, and / or light chain of a polypeptide described herein.

[0269] An expression vector can be transferred to a cell (e.g., host cell) by conventional techniques and the resulting cells can then be cultured by conventional techniques to produce a polypeptide described herein or a fragment thereof. Thus, provided herein are host cells containing a polynucleotide encoding containing a polypeptide described herein or fragments thereof, or a heavy or light chain thereof, or fragment thereof, or a single chain antibody described herein, operably linked to a promoter for expression of such sequences in the host cell.

[0270] In an embodiment, a host cell comprises a polynucleotide comprising one of the first nucleotide sequences and one of the second nucleotide sequences described above. In another embodiment, a host cell comprises a first polynucleotide comprising one of the first nucleotide sequences described above, and a second polynucleotide comprising one of the first nucleotide sequences described above. In another embodiment, a host cell comprises a first vector comprising one of the first nucleotide sequences and one of the second nucleotide sequences described above. In another embodiment, a host cell comprises a first vector comprising one of the first nucleotide sequences and one of the second nucleotide sequences described above, and a second vector comprising a second polynucleotide comprising one of the first nucleotide sequences described above.

[0271] In some embodiments, an IgG-binding molecule expressed by a first host cell is associated with an IgG-binding molecule expressed by a second host cell to form a two-armed IgG-binding molecule. In some embodiments, an IgG-binding molecule expressed by a first host cell is associated with an FcRn-binding molecule expressed by a second host cell to form a one-92329912564Docket No. ARGX-T2501 / 01 WOarmed IgG-binding molecule. In some embodiments, provided herein are populations of host cells comprising such first host cells and such second host cells.

[0272] In some embodiments, provided herein is a population of vectors comprising a first vector comprising a polynucleotide encoding an IgG-binding molecule, and a second vector comprising a polynucleotide encoding an IgG-binding molecule. In some embodiments, provided herein is a population of vectors comprising a first vector comprising a polynucleotide encoding an IgG-binding molecule, and a second vector comprising a polynucleotide encoding an IgG-binding molecule. In some embodiments, provided herein is a population of vectors comprising a first vector comprising a polynucleotide encoding an IgG-binding molecule and a polynucleotide encoding an IgG-binding molecule. In some embodiments, provided herein is a population of vectors comprising a first vector comprising a polynucleotide encoding two IgG-binding molecules.

[0273] A variety of host-expression vector systems can be utilized to express polypeptides described herein (see, e.g., U.S. Patent No. 5,807,715, which is herein incorporated by reference in its entirety). Such host-expression systems represent vehicles by which the coding sequences of interest can be produced and subsequently purified, but also represent cells which can, when transformed or transfected with the appropriate nucleotide coding sequences, express a polypeptide described herein in situ. These include but are not limited to microorganisms such as bacteria (e.g., E. coli and B. subtilis') transformed with, e.g., recombinant bacteriophage DNA, plasmid DNA, or cosmid DNA expression vectors containing IgG-binding molecule coding sequences; yeast (e.g., Saccharomyces and Pichia) transformed with, e.g., recombinant yeast expression vectors containing IgG binding molecule coding sequences; insect cell systems infected with, e.g., recombinant virus expression vectors (e.g., baculovirus) containing IgG-binding molecule coding sequences; plant cell systems (e.g., green algae such as Chlamydomonas reinhardtii) infected with, e.g., recombinant virus expression vectors (e.g., cauliflower mosaic virus, CaMV; tobacco mosaic virus, TMV) or transformed with, e.g., recombinant plasmid expression vectors (e.g., Ti plasmid) containing IgG-binding molecule coding sequences; or mammalian cell systems (e.g., COS (e.g., COS1 or COS), CHO, BHK, MDCK, HEK 293, NS0, PER.C6, VERO, CRL7O3O, HsS78Bst, HeLa, NIH 3T3, HEK-293T, HepG2, SP210, Rl.l, B-W, L-M, BSC1, BSC40, YB / 20, and BMT10 cells) harboring, e.g., recombinant expression constructs containing promoters derived from the genome of mammalian cells (e.g., metallothionein promoter) or from mammalian viruses (e.g., the adenovirus late promoter; the vaccinia virus 7.5K 93329912564Docket No. ARGX-T2501 / 01 WOpromoter). In an embodiment, cells for expressing IgG-binding molecules described herein are Chinese hamster ovary (CHO) cells, for example CHO cells from the CHO GS System™ (Lonza). In an embodiment, the heavy chain and / or light chain produced by a CHO cell may have an N-terminal glutamine or glutamate residue replaced by pyroglutamate. In an embodiment, cells for expressing polypeptides described herein are human cells, e.g., human cell lines. In an embodiment, a mammalian expression vector is pOptiVEC™ or pcDNA3.3. In an embodiment, bacterial cells such as Escherichia co . or eukaryotic cells (e.g., mammalian cells), are used for the expression of a recombinant polypeptide. For example, mammalian cells such as CHO cells, in conjunction with a vector such as the major intermediate early gene promoter element from human cytomegalovirus, are an effective expression system for antibodies (Foecking MK & Hofstetter H (1986) Gene 45: 101-5; and CockettMI etal., (1990) Biotechnology . 662-7, each of which is herein incorporated by reference in its entirety). In an embodiment, polypeptides described herein are produced by CHO cells or NSO cells. In an embodiment, the expression of nucleotide sequences encoding polypeptides described herein which comprise two, three, or four binding sites for human FcRn is regulated by a constitutive promoter, inducible promoter, or tissue specific promoter.

[0274] In bacterial systems, a number of expression vectors can be advantageously selected depending upon the use intended for the molecule being expressed. For example, when a large quantity of such a polypeptide is to be produced, for the generation of pharmaceutical compositions of an antibody molecule, vectors which direct the expression of high levels of fusion protein products that are readily purified can be desirable. Such vectors include, but are not limited to, the E. coli expression vector pUR278 (Ruether U & Mueller-Hill B (1983) EMBO J 2: 1791- 1794), in which the coding sequence can be ligated individually into the vector in frame with the lac Z coding region so that a fusion protein is produced; pIN vectors (Inouye S & Inouye M (1985) Nuc Acids Res 13: 3101-3109; Van Heeke G & Schuster SM (1989) J Biol Ghent 24: 5503-5509); and the like, all of which are herein incorporated by reference in their entireties. For example, pGEX vectors can also be used to express foreign polypeptides as fusion proteins with glutathione 5-transferase (GST). In general, such fusion proteins are soluble and can easily be purified from lysed cells by adsorption and binding to matrix glutathione agarose beads followed by elution in the presence of free glutathione. The 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.94329912564Docket No. ARGX-T2501 / 01 WO

[0275] In an insect system, Autographa californica nuclear polyhedrosis virus (AcNPV), for example, can be used as a vector to express foreign genes. The virus grows in Spodoptera frugiperda cells. The coding sequence can be cloned individually into non-essential regions (for example the polyhedrin gene) of the virus and placed under control of an AcNPV promoter (for example the polyhedrin promoter).

[0276] In mammalian host cells, a number of viral-based expression systems can be utilized. In cases where an adenovirus is used as an expression vector, the coding sequence of interest can be ligated to an adenovirus transcript! on / translati on control complex, e.g, the late promoter and tripartite leader sequence. This chimeric gene can then be inserted in the adenovirus genome by in vitro or in vivo recombination. Insertion in a non-essential region of the viral genome (e.g, region El or E3) will result in a recombinant virus that is viable and capable of expressing the molecule in infected hosts (see, e.g., Logan J & Shenk T (1984) PNAS 81(12): 3655-9, which is herein incorporated by reference in its entirety). Specific initiation signals can also be required for efficient translation of inserted coding sequences. These signals include the ATG initiation codon and adjacent sequences. Furthermore, 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 translational control signals and initiation codons can be of a variety of origins, both natural and synthetic. The efficiency of expression can be enhanced by the inclusion of appropriate transcription enhancer elements, transcription terminators, etc. (see, e.g., Bitter G et al., (1987) Methods Enzymol. 153: 516-544, which is herein incorporated by reference in its entirety).

[0277] In addition, a host cell strain can be chosen which modulates the expression of the inserted sequences or modifies and processes the gene product in the specific fashion desired. Such modifications (e.g., glycosylation) and processing (e.g., cleavage) of protein products can be important for the function of the protein. Different host cells have characteristic and specific mechanisms for the post-translational processing and modification of proteins and gene products. Appropriate cell lines or host systems can be chosen to ensure the correct modification and processing of the foreign protein expressed. To this end, eukaryotic host cells which possess the cellular machinery for proper processing of the primary transcript, glycosylation, and phosphorylation of the gene product can be used. Such mammalian host cells include but are not limited to CHO, VERO, BHK, HeLa, MDCK, HEK 293, NIH 3T3, W138, BT483, Hs578T, HTB2, BT2O, and T47D, NS0 (a murine myeloma cell line that does not endogenously produce any immunoglobulin chains), CRL7O3O, COS (e.g., COS1 or COS), PER.C6, VERO, HsS78Bst,95329912564Docket No. ARGX-T2501 / 01 WOHEK-293T, HepG2, SP210, Rl.l, B-W, L-M, BSC1, BSC40, YB / 20, BMT10, and HsS78Bst cells. In an embodiment, proteins described herein are produced in mammalian cells, such as CHO cells.

[0278] In an embodiment, a polypeptide described herein comprises a portion of an antibody with reduced fucose content or no fucose content. Such proteins can be produced using techniques known to one skilled in the art. For example, the proteins can be expressed in cells deficient in or lacking the ability to fucosylate. In an example, cell lines with a knockout of both alleles of al,6-fucosyltransferase can be used to produce antibodies with reduced fucose content. The Potelligent® system (Lonza) is an example of such a system that can be used to produce antibodies with reduced fucose content.

[0279] For long-term, high-yield production of recombinant proteins, stable expression cells can be generated. For example, cell lines which stably express a protein described herein can be engineered. In an embodiment, a cell provided herein stably expresses an IgG-binding domain, an IgG-binding molecule, or an FcRn-binding molecule which associate to form a one-armed or two-armed polypeptide described herein.

[0280] In certain aspects, rather than using expression vectors which contain viral origins of replication, host cells can be transformed with DNA controlled by appropriate expression control elements (e.g., promoter, enhancer, sequences, transcription terminators, polyadenylation sites, etc.), and a selectable marker. Following the introduction of the foreign DNA / polynucleotide, engineered cells can be allowed to grow for one to two days in an enriched media, and then are switched to a selective media. The selectable marker in the recombinant plasmid confers resistance to the selection and allows cells to stably integrate the plasmid into their chromosomes and grow to form foci, which in turn can be cloned and expanded into cell lines. This method can advantageously be used to engineer cell lines which express a polypeptide comprising two, three, or four binding sites for human FcRn described herein or a fragment thereof. Such engineered cell lines can be particularly useful in the screening and evaluation of compositions that interact directly or indirectly with the polypeptide.

[0281] A number of selection systems can be used, including but not limited to the herpes simplex virus thymidine kinase (Wigler M el al., (1977) Cell 11(1): 223-32), hypoxanthineguanine phosphoribosyltransferase (Szybalska EH & Szybalski W (1962) PNAS 48(12): 2026-2034) and adenine phosphoribosyltransferase (Lowy I et al., (1980) Cell 22(3): 817-23) genes in tk-, hgprt-or aprt-cells, respectively, all of which are herein incorporated by reference in their entireties. Also,96329912564Docket No. ARGX-T2501 / 01 WOantimetabolite resistance can be used as the basis of selection for the following genes: dhfr, which confers resistance to methotrexate (Wigler M et al., (1980) PNAS 77(6): 3567-70; O’Hare K et al., (1981) PNAS 78: 1527-31); gpt, which confers resistance to mycophenolic acid (Mulligan RC & Berg P (1981) PNAS 78(4): 2072-6); neo, which confers resistance to the aminoglycoside G-418 (Wu GY & Wu CH (1991) Biotherapy 3: 87-95; Tolstoshev P (1993) Ann Rev Pharmacol Toxicol 32: 573-596; Mulligan RC (1993) Science 260: 926-932; and Morgan RA & Anderson WF (1993) Ann Rev Biochem 62: 191-217; Nabel GJ & Feigner PL (1993) Trends Biotechnol 11(5): 211-5); and hygro, which confers resistance to hygromycin (Santerre RF etal., (1984) Gene 30(1-3): 147-56), all of which are herein incorporated by reference in their entireties. Methods commonly known in the art of recombinant DNA technology can be routinely applied to select the desired recombinant clone and such methods are described, for example, in Ausubel FM et al., (eds.), Current Protocols in Molecular Biology, John Wiley & Sons, NY (1993); Kriegler M, Gene Transfer and Expression, A Laboratory Manual, Stockton Press, NY (1990); and in Chapters 12 and 13, Dracopoli NC et al., (eds.), Current Protocols in Human Genetics, John Wiley & Sons, NY (1994); Colbere-Garapin F et al., (1981) J Mol Biol 150: 1-14, all of which are herein incorporated by reference in their entireties.

[0282] The expression levels of a polypeptide can be increased by vector amplification (for a review, see, Bebbington CR & Hentschel CCG, The use of vectors based on gene amplification for the expression of cloned genes in mammalian cells in DNA cloning, p. 163-188. In DNA Cloning, Vol III, A Practical Approach. D. M. Glover (Ed.) (Academic Press, New York, 1987), which is herein incorporated by reference in its entirety). When a marker in the vector system is amplifiable, increase in the level of inhibitor present in culture of host cell will increase the number of copies of the marker gene. Since the amplified region is associated with the gene of interest, production of the polypeptide will also increase (Crouse GF et al., (1983) Mol Cell Biol 3: 257-66, which is herein incorporated by reference in its entirety).

[0283] The host cell can be co-transfected with two or more expression vectors described herein. The two vectors can contain identical selectable markers which enable equal expression of polypeptides, such as a first heavy chain and a second heavy chain polypeptide. The host cells can be co-transfected with different amounts of the two or more expression vectors. For example, host cells can be transfected with any one of the following ratios of a first expression vector and a second expression vector: about 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:12, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, or 1:50.97329912564Docket No. ARGX-T2501 / 01 WO

[0284] Alternatively, a single vector can be used which encodes, and is capable of expressing, both polypeptides. The coding sequences can comprise cDNA or genomic DNA. The expression vector can be monocistronic or multi ci str onic. A multi ci str onic nucleic acid construct can encode 2, 3, 4, 5, 6, 7, 8, 9, 10, or more genes / nucleotide sequences, or in the range of 2-5, 5-10, or 10-20 genes / nucleotide sequences. For example, a bicistronic nucleic acid construct can comprise, in the following order, a promoter, a first gene and a second gene. In such an expression vector, the transcription of both genes can be driven by the promoter, whereas the translation of the mRNA from the first gene can be by a cap-dependent scanning mechanism, and the translation of the mRNA from the second gene can be by a cap-independent mechanism, e.g., by an IRES.

[0285] Once a polypeptide described herein has been produced by recombinant expression, it can be purified by any method known in the art for purification of a protein, for example, by chromatography (e.g., ion exchange, affinity, particularly by affinity for the specific antigen after Protein A, and sizing column chromatography), centrifugation, differential solubility, or by any other standard technique for the purification of proteins. Further, the polypeptides described herein can be fused to heterologous polypeptide sequences described herein or otherwise known in the art to facilitate purification.

[0286] In an embodiment, a polypeptide described herein is isolated or purified. In an embodiment, an isolated polypeptide is one that is substantially free of other polypeptides with different antigenic specificities than the isolated polypeptide. For example, in certain embodiments, a preparation of a protein described herein is substantially free of cellular material and / or chemical precursors. The language “substantially free of cellular material” includes preparations of a polypeptide in which the polypeptide is separated from cellular components of the cells from which it is isolated or recombinantly produced. Thus, a polypeptide that is substantially free of cellular material includes preparations of polypeptide having less than about 30%, 20%, 10%, 5%, 2%, 1%, 0.5%, or 0.1% (by dry weight) of heterologous protein (also referred to herein as a “contaminating protein”) and / or variants of a polypeptide, for example, different post-translational modified forms of a polypeptide or other different versions of a polypeptide (e.g. , polypeptide fragments). When the polypeptide is recombinantly produced, it is also generally substantially free of culture medium, z.e., culture medium represents less than about 20%, 10%, 2%, 1%, 0.5%, or 0.1% of the volume of the protein preparation. When the polypeptide is produced by chemical synthesis, it is generally substantially free of chemical precursors or other chemicals, z.e., it is separated from chemical precursors or other chemicals, which are involved in the synthesis 98329912564Docket No. ARGX-T2501 / 01 WOof the protein. Accordingly, such preparations of the protein have less than about 30%, 20%, 10%, or 5% (by dry weight) of chemical precursors or compounds other than the molecule of interest. In an embodiment, polypeptides described herein are isolated or purified.

[0287] A polypeptide described herein can be produced by any method known in the art for the synthesis of proteins, for example, by chemical synthesis or by recombinant expression techniques. The methods described herein employ, unless otherwise indicated, conventional techniques in molecular biology, microbiology, genetic analysis, recombinant DNA, organic chemistry, biochemistry, PCR, oligonucleotide synthesis and modification, nucleic acid hybridization, and related fields within the skill of the art. These techniques are described, for example, in the references cited herein and are fully explained in the literature. See, e.g., Maniatis T etal., (1982) Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory Press; Sambrook J etal., (1989), Molecular Cloning: A Laboratory Manual, Second Edition, Cold Spring Harbor Laboratory Press; Sambrook J el al., (2001) Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY; Ausubel FM et al., Current Protocols in Molecular Biology, John Wiley & Sons (1987 and annual updates); Current Protocols in Immunology, John Wiley & Sons (1987 and annual updates); Gait (ed.) (1984) Oligonucleotide Synthesis: A Practical Approach, IRL Press; Eckstein (ed.) (1991) Oligonucleotides and Analogues: A Practical Approach, IRL Press; Birren B et al., (eds.) (1999) Genome Analysis: A Laboratory Manual, Cold Spring Harbor Laboratory Press, all of which are herein incorporated by reference in their entireties.

[0288] In an embodiment, a polypeptide described herein is prepared, expressed, created, or isolated by any means that involves creation, e.g., via synthesis, genetic engineering of DNA sequences. In an embodiment, such a polypeptide comprises sequences (e.g., DNA sequences or amino acid sequences) that do not naturally exist within the antibody germline repertoire of an animal or mammal (e.g., human) in vivo.Pharmaceutical Compositions

[0289] In an aspect, the instant disclosure provides pharmaceutical compositions comprising an IgG-binding molecule as disclosed herein for use in methods of treating an antibody-mediated disorder (e.g., an autoantibody-mediated disorder). In certain embodiments, these compositions comprise an IgG-binding molecule comprising an FcRn-binding molecule and an IgG-binding domain. In some embodiments, the FcRn-binding molecule is an FcRn antagonist.99329912564Docket No. ARGX-T2501 / 01 WOThe compositions disclosed herein include bulk drug compositions useful in the manufacture of pharmaceutical compositions (e.g., compositions that are suitable for administration to a subject or patient) which can be used in the preparation of unit dosage forms. In an embodiment, a composition of the invention is a pharmaceutical composition. Such compositions comprise a prophylactically or therapeutically effective amount of one or more prophylactic or therapeutic agents (e.g., an IgG-binding molecule) of the invention (or other prophylactic or therapeutic agent), and a pharmaceutically acceptable carrier.Methods of Treatment

[0290] The disclosure also provides methods for treating an antibody-mediated disorder (e.g., an autoantibody-mediated disorder) in a subject comprising administering to the subject a therapeutically effective amount of an IgG-binding molecule according to the disclosure or a pharmaceutical composition comprising the same. In some embodiments, the antibody-mediated disorder is an IgG-mediated disorder. In some embodiments, the antibody-mediated disorder is an autoimmune disease.

[0291] The disclosure provides methods of reducing serum IgG in a subject comprising administering to the subject a therapeutically effective amount of an IgG-binding molecule according to the disclosure or a pharmaceutical composition comprising the same. In an embodiment, at least one of the IgG subtypes is reduced in a subject following administration of the IgG-binding molecule. In some embodiments, IgGl, IgG2, IgG3, IgG4, or any combination thereof is reduced. In some embodiments, the administration of the IgG-binding molecule is a single administration (e.g., a single therapeutic administration) of the IgG-binding molecule. In an embodiment, the level of serum IgG is decreased in the subject following administration of the IgG-binding molecule compared to a baseline level of serum IgG.EXAMPLES

[0292] The following examples are offered by way of illustration, and not by way of limitation.Example 1: Identification of anti-IgG antibodies binding at the FcRn binding site

[0293] Four rounds of phage display selections using phage from eight constructed Fab phage display immune libraries were performed on wild-type Fc-containing full-length antibody 100329912564Docket No. ARGX-T2501 / 01 WOincluding counter-selection with Fc-ABDEG (efgartigimod) in high molar excess. In parallel, pH dependent and total elution strategies were used to enrich for clones with higher dissociation rates at pH 5.5 than pH 7.4.

[0294] Specifically, eight phage display llama Fab libraries generated from immunization campaigns with human Fc-tagged recombinant proteins were screened to select antibodies that bind to the wild-type FcRn binding site with counter selection using Fc-ABDEG.

[0295] Further screening for specificity was performed by periplasmic extract (P.E.) binding ELISA on huIgGl WT, Fc-ABDEG, Fc-NHance, huIgG2_WT, huIgG3_WT, and huIgG4_WT, and P.E. binding SPR on Fc-ABDEG, Fc-NHance, mouse serum IgG, and cynomolgus monkey IgG proteins.

[0296] pH dependent target binding was evaluated by P.E. binding ELISA on huIgGl WT and P.E. SPR on huIgGl WT, huIgG2_WT, huIgG3_WT, huIgG4_WT, Fc-ABDEG, Fc-NHance, and cyno full IgG at pH 7.4 and pH 5.5.

[0297] Off-rate determination was evaluated by SPR on huIgGl WT at pH 7.4 and pH 5.5.

[0298] From the total of 368 clones screened, 334 showed binding to huIgGl WT (positive binding defined by >35 binding RUs). From the eight libraries screened, 243 clones were identified with pH-dependent binding (kd pH 5.5 / kd pH 7.4 > 2.0).

[0299] All screened clones bound to huIgG2_WT, 92.5% of the clones bound to huIgG3, and 90% of the clones bound to huIgG4. 172 of the 174 unique clones showed positive binding to Fc-NHance (RUmax > 25 RUs). 16 of the 174 unique clones showed positive binding to Fc-ABDEG (RUmax > 25 RUs). 47 of the 174 unique clones showed positive binding to total mouse IgG isolated from serum (RUmax > 25 RUs).

[0300] Around 40% of the 174 unique clones showed pH-dependent huIgGl WT binding as determined by ELISA. Further screening by SPR on huIgGl WT identified a total of 38 unique clones with a kd pH 5.5 / kd pH 7.4 > 2.0. After excluding unique clones with positive binding to Fc-ABDEG, 22 clones were selected for further study.

[0301] A summary of the P.E. SPR results of the 22 selected clones is presented in Table 10. Secondary pH-dependency screenings identified a further 10 clones. Data from the secondary pH screenings are presented in Tables 11 and 12. Amino acid sequences for these 32 clones are provided above.101329912564Docket No. ARGX-T2501 / 01 WOTable 10: SPR data* Below detection limit102329912564Docket No. ARGX-T2501 / 01 WOTable 11: Secondary pH dependency screening datand = not detected (RUmax <10 RU)Table 12: Secondary pH dependency screening data> >103329912564Docket No. ARGX-T2501 / 01 WOnd = not detected (RUmax <10 RU)104329912564Docket No. ARGX-T2501 / 01 WO

[0302] As shown in Tables 11-12, for the most pH-dependent anti-IgG Fabs, the binding to hu!gG3 is negligible. Additionally, two clones (01F01 and 01E02) showed high affinity binding and two clones (05A01 and 03H10) showed some residual binding to Fc-ABDEG, which was not observed during the earlier P.E. screening. Of note, the LALA mutation, located in the upper CH2 region close to the hinge, did not influence binding of the Fabs to huIgGl. However, the IHH mutation significantly impacted binding of the Fabs to huIgGl, further confirming that these Fabs interact with IgGs in the FcRn-binding region (Table 13).

[0303] Five clones with high affinity binding to all IgG subclasses and not (or residually) to Fc-ABDEG were produced as full length (z.e., two-armed) antibodies in a huIgGl-ABDEG backbone: 02F11, 01C07, 03H10, 02A10, and 01E12. The resulting antibodies were screened for their affinity to the different IgG subclasses.

[0304] Except for the binding of 01E12 to IgG3, a high binding affinity for the different IgG subclasses was obtained for all clones (Table 14), which confirms the data from the Fab screening. The affinities for the different IgG subclasses are in the sub-nanomolar range, since the two-armed antibodies also display an avidity effect for binding to IgGs. The selected clones showed mild pH-dependency characteristics, similar to that seen during Fab screening. Clone 05A01, which showed the best pH-dependency characteristics as a Fab but insufficient binding to certain IgG subclasses, was included in further screening as a reference of a very pH-dependent clone.105329912564Docket No. ARGX-T2501 / 01 WOTable 13: Binding affinity of anti-IgG full-length ABDEG antibodies for different IgG subclassesTable 14: Binding affinity of anti-IgG full-length ABDEG antibodies for different IgG subclasses106329912564Docket No. ARGX-T2501 / 01 WOnd = not detected (RUmax <10 RU)107329912564Docket No. ARGX-T2501 / 01 WOExample 2: Characterization of one-armed anti-IgG-huIgGl-ABDEG antibodies

[0305] After the initial screenings of the anti-IgG antibodies described in Example 1, five anti-IgG clones were produced in a one-armed (OA) huIgGl-ABDEG format as assessed for IgG subtype affinity, pH dependency, FcRn occupancy, and FcRn degradation.

[0306] The selection of the clones was based on their binding to IgG3 and / or pH-dependent properties: (1) OA-01A07-hIgGl-ABDEG (not pH-dependent; control); (2) OA-01C07-hIgGl-ABDEG; (3) OA-02A10-hIgGl-ABDEG; (4) OA-03H10-hIgGl-ABDEG; (4) OA-05A01-hIgGl-ABDEG.

[0307] The five OA-anti-IgG-huIgGl-ABDEG antibodies were screened for their binding affinity to the different IgG subclasses, huIgGl-ABDEG and huIgG4-NHhance. Data are presented in Table 15.108329912564Docket No. ARGX-T2501 / 01 WOTable 15: Binding affinity of anti-IgG OA-ABDEG antibodies for different IgG subclasses and variants109329912564Docket No. ARGX-T2501 / 01 WO110329912564Docket No. ARGX-T2501 / 01 WO

[0308] For all the OA-anti-IgG-huIgGl-ABDEG antibodies, the nanomolar affinities for the different IgG subclasses at pH 7.4 seen during the Fab screening were confirmed. Again, the most pH-dependent clone OA-05A01-hIgGl-ABDEG showed no binding to IgGs at pH 5.5 and low binding to hu!gG3_WT at pH 7.4. The data confirms that 01 A07 is not pH-dependent, while all the other clones show lower affinities at pH 5.5 compared to pH 7.4.

[0309] The kinetic properties for OA-05A01-hIgGl-ABDEG at pH 5.5 could not be determined properly due to low binding. This results in inaccurate estimations of the KD and therefore also of the pH-dependency ratios. The strong pH-dependency of OA-05A01-hIgGl-ABDEG can be observed by comparing the dissociation rate constants (kd).

[0310] Only slight residual binding could be observed for some of the OA-anti-IgG-huIgGl-ABDEG antibodies to huIgGl ABDEG. The binding of the different clones to hu!gG4-NHance is clone dependent: OA-01A07-hIgGl-ABDEG, OA-03H10-hIgGl-ABDEG and OA-05A01-hIgGl-ABDEG (residually) display binding to IgG4-NHance, while the other clones do not.

[0311] FcRn occupancy of four OA-anti-IgG-huIgGl-ABDEG antibodies with and without complexing of IVIg was assessed. For comparison, TA-02A10-huIgGl-ABDEG (z.e., full-length 02A10-huIgGl-ABDEG) and Fc-ABDEG (ARGX-113, efgartigimod) were also analyzed. Briefly, monocytic U937 cells, which express FcRn and FcyR, were incubated with a titration series of the test items alone or in immune complex (IC) with IgG (IVIg or huIgG tracer). Free FcRn was detected with a fluorescently labelled anti-FcRn Fab fragment recognizing IgG binding site on FcRn. Data are presented relative to 100% of unoccupied FcRn along with the IC50.

[0312] Consistent with previous findings, one-armed antibodies occupy FcRn to a greater extent than two-armed antibodies (FIG. 1 and Table 16). Efgartigimod (ARGX-113) has a better occupancy compared to the OA-anti-IgG-huIgGl-ABDEG antibodies. The anti-IgG antibodies in complex with IVIg occupy FcRn less compared to the antibodies without complex, especially seen for the two-armed antibody that can form bigger complexes (Table 16).Table 16: FcRn occupancy after incubation of with anti-IgG-ABDEG antibodies in the presence or absence of IVIg in U937 cells111329912564Docket No. ARGX-T2501 / 01 WO

[0313] Previous studies have shown that anti-FcRn antibodies decrease serum albumin when administered to patients. It is believed that this effect is mediated, at least in part, by degradation of FcRn induced by these anti-FcRn antibodies.

[0314] Thus, the effect of OA-anti-IgG-ABDEG antibodies on FcRn degradation was explored using a cell-based assay in the presence or absence of complexation with huIgGl . Briefly, HEK FcRn WT GFP+ cells / well were seeded on a 96-well microplate overnight at 37°C in growth medium (DMEM + 10% FBS + P / S + L-glutamine). OA-anti-IgG-ABDEG antibodies were preincubated with huIgGl in a 1:1 ratio in treatment medium (DMEM + 1% BSA + P / S + L-glutamine) for 30 minutes at 37°C prior to adding to the cells. After incubation of the OA-anti-IgG-ABDEG antibody / huIgGl mix or OA-anti-IgG-ABDEG antibody with the cells, plates were then placed on ice and cells harvested by trypsin. Harvested cells were transferred to FACS plate and centrifuged. LD stain (1 :800) was added in FACS buffer and incubated for 15 minutes at 4°C. Cells were washed, centrifuged, and resuspended in FACS buffer. GFP signal was measured and compared to untreated controls. An anti-FcRn antibody known to degrade FcRn (anti-FcRn mAb 1) was included as a positive control. Anti-FcRn mAbl comprises the light chain sequence of SEQ ID NO: 458 and the heavy chain sequence of SEQ ID NO: 459.

[0315] SEQ ID NO: 458:SYVLTQSPSVSVAPGQTARITCGGNNIGSKSVHWYQQKPGQAPVLWYDDSDRPSGIPERFSAS NSGNTATLTISRVEAGDEADYYCQVWDSSSDHVVFGGGTKLTVLGQPKAAPSVTLFPPSSEELQ ANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPSKQSNNKYAASSYLSLTPEQWKSHRS YSCQVTHEGSTVEKTVAPTECS

[0316] SEQ ID NO: 459:QLLLQESGPGLVKPSETLSLTCTVSGGSLSSSFSYWVWIRQPPGKGLEWIGTIYYSGNTYYNPS LKSRLTISVDTSKNHFSLKLSSVTAADTAVYYCARRAGILTGYLDSWGQGTLVTVSSASTKGPS VFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLJQSSGLYSLSSVVTV PSSSLGTQTYICNVNHKPSNTKVDKRVEPKSCDKTHTCPPCPAPEAAGGPSVFLJFPPKPKDTLJM112329912564Docket No. ARGX-T2501 / 01 WOISRTPEVTCVWDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRWSVLTVLHQDWLNG KEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVE WESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLS PG

[0317] Data are shown in FIG.2A. For the five OA-anti-IgG-huIgGl-ABDEG antibodies with or without complexation with huIgGl, no statistically significant increase or reduction in percentage of FcRn compared to untreated cells could be observed (FIG. 2A). The data for OA-01C07-huIgGl-ABDEG and OA-02A10-huIgGl-ABDEG in complex with huIgGl show no errors bars, because one data point was excluded for each due to low cell counts.

[0318] This experiment was also conducted in U937 cells (FIG.2B). Unlike the data from HEK FcRn WT GFP+ cells, significant increases in FcRn were seen for all five OA-anti-IgG-huIgGl-ABDEG antibodies in complex in huIgGl and for two OA-anti-IgG-huIgGl-ABDEG antibodies alone (OA-01A07-huIgGl-ABDEG and OA-02A10-huIgGl-ABDEG).

[0319] In summary, for all the OA-anti-IgG-huIgGl-ABDEG antibodies, high nanomolar affinities for the different IgG subclasses at pH 7.4 were confirmed, as well as pH-dependency. Only slight residual binding could be observed for some of the antibodies to ABDEG-backbone, while the binding to HN-backbones (NHance mutations: 433K / 434F) showed to be very clonespecific. As expected, OA-anti-IgG-huIgGl-ABDEG antibodies occupy FcRn to a greater extent than two-armed antibodies (e.g., full-length antibodies), but to a lesser extent than Efgartigimod (ARGX-113). The anti-IgG antibodies in complex with IVIg or huIgGl occupy FcRn less compared to the antibodies without complex, especially seen for the two-armed antibody that can form bigger complexes. FcRn degradation was also evaluated for the five OA-anti-IgG-huIgGl-ABDEG antibodies with and without pre-complexing with huIgGl using two different cell lines, HEK-FcRn-GFP and U937 cells. None of the five OA-anti-IgG-huIgGl-ABDEG antibodies showed a statistically significant reduction in percentage of FcRn compared to untreated cells. The discrepancies between the different amounts of FcRn degradation using these different cell types for the OA-anti-IgG-huIgGl-ABDEG antibodies in complex with huIgGl is not yet clear. HEK-FcRn-GFP cells do not (or to a very limited extent) express Fey receptors but overexpress FcRn. The monocytic cell line U937 expresses endogenous levels of both FcRn and Fey receptors. Thus, the presence / absence of Fey receptors or the difference in FcRn expression levels between both cell types might influence these discrepancies.113329912564Docket No. ARGX-T2501 / 01 WO

[0320] Three OA-IgG-ABDEG antibodies were selected for further development based on in vitro characterization: OA-01A07-huIgGl-ABDEG, OA-02A10-huIgGl-ABDEG, and OA-05 AO 1 -huIgGl -AB DEG.Example 3: In vivo characterization of one-armed anti-IgG-hnlgGl-ABDEG antibodies

[0321] The goal of the following experiment was to assess the pharmacodynamics and pharmacokinetics of anti-IgG-ABDEG and anti-IgG-ABDEG-like sweeping antibodies. Different antigen-binding domains (Fabs) and engineered fragment crystallizable regions (Fc) were analyzed, aiming to better understand the requirements for fast and deep IgG reduction by anti-IgG sweepers.

[0322] Study 1 : A total of 20 Albumus RaglKO mice were used in this study, to assess the role of pH-dependent binding in the sweeping capacity of an IgG-sweeper. Mice were randomly assigned into 8 groups and single-dosed intraperitoneally (IP) with huIgG (200 mg / kg huIVIg and 20 mg / kg huIgGl tracer) on day -3 to establish a basal level of circulating huIgG in Albumus mice (low endogenous levels of mouse IgG). On day 0, mice were injected IP (250 pL injection volume, reference weight 25 g) according to the groups, doses, and bleeding scheme described in Table 17.Table 17: Groups and dosing regimen for Study 1

[0323] Study 2: A total of 35 Albumus RaglKO mice were used in this study, to assess the role of affinity to FcRn in the sweeping capacity of an IgG-sweeper. Mice were randomly assigned into 8 groups and single-dosed IP with huIgG (200 mg / kg huIVIg and 20 mg / kg huIgGl tracer) on day -3 to establish a basal level of circulating huIgG in Albumus mice (low endogenous levels of mouse IgG). On day 0, mice were injected IP (250 pL injection volume, reference weight 25 g) according to the groups, doses, and bleeding scheme described in Table 18.114329912564Docket No. ARGX-T2501 / 01 WOTable 18: Groups and dosing regimen for Study 2Results

[0324] Study 1:

[0325] In the first study, the role of pH-dependent binding on the sweeping capacity of an IgG-sweeper was assessed by comparing anti-IgG clones 01A07, 02A10, and 05A01 in an OA-ABDEG format.

[0326] To evaluate the PK profiles of the test articles after a single IP administration, their levels in mouse serum were determined during the course of the study according to the bleeding scheme in Table 17. The obtained values were plotted in pg / mL. From dosing group OA-mAb37-ABDEG, mouse 2 was underdosed, as seen by the lower concentrations at D0+2h, but was still included in the analysis since PK profiles matched other mice of the respective dosing group. Mouse 5 was not injected and thus excluded. From dosing group OA-01A07-ABDEG, mouse 4 died at the start of the experiment, before test item injection, and data could not be collected. From dosing group OA-05A01-ABDEG, mouse 3 was not preloaded with IVIg and IgGl tracer and therefore excluded.

[0327] PK analysis demonstrates a similar exposure for OA-mAb37-ABDEG (control) and OA-02A10-ABDEG, while a lower exposure is seen for OA-01A07-ABDEG and OA-05A01-ABDEG (FIG. 3).115329912564Docket No. ARGX-T2501 / 01 WO

[0328] PD effect of the one-armed IgG sweeping antibodies was evaluated on clearance of total IgG (preloaded huIVIg). The measured concentrations during the course of the study were plotted as total concentrations (FIG. 4A) and percentage to pre-dose (5 min prior to test article injection, FIG. 4B) per treatment group. From dosing group OA-mAb37-ABDEG, mouse 2 was underdosed (see PK), but was still included in the analysis since PD profiles matched other mice of the respective dosing group. Mouse 5 of OA-mAb37-ABDEG was not injected and thus excluded. From dosing group OA-01 A07-ABDEG, mouse 4 died at the start of the experiment and data could not be collected. From dosing group OA-05A01-ABDEG, mouse 3 was not preloaded with IVIg and IgGl tracer and therefore excluded.

[0329] A PD effect was observed for all molecules, with the OA IgG-sweepers outcompeting the control OA-mAb37-ABDEG group, which does not bind IgGs, but only blocks FcRn due to the ABDEG mutations. Both OA-01 A07-AB DEG and OA-02A10-ABDEG resulted in a ±80% decrease in preloaded huIgGs within the first day. OA-05A01 -ABDEG resulted in a very strong reduction of preloaded huIgGs to more than 90% in the first day, and more than 99% after 3 days. Similar results were shown when measuring clearance of huIgGl tracer (data not shown).

[0330] Study 2:

[0331] In the second study, the role of affinity to FcRn in the sweeping capacity of an IgG-sweeper was assessed by comparing ABDEG-like mutations that result in different affinities for FcRn at pH 7.4 and 6. Specifically, a comparison was made between ABDEG (benchmark), LALAPG- ABDEG, YPY, and YY in a OA-02A10 format. The results with OA-05A10-ABDEG were also confirmed in this study.

[0332] To evaluate the PK profiles of the test articles after a single IP administration, their levels in mouse serum were determined during the course of the study according to the bleeding scheme in Table 18. The obtained values were plotted in pg / mL. From dosing group OA-02A10-YPY, mouse 2 was underdosed, as seen by the lower concentrations at D0±lh, but was still included in the analysis of the PK profiles.

[0333] PK analysis demonstrated that all OA-molecules showed a longer PK compared to efgartigimod (ARGX-113), due at least in part to the increased size. The inclusion of LALAPG resulted in a longer PK, while ABDEG and YY resulted in a similar PK. YPY, having a very high affinity for FcRn at both pH 7.4 and 6, reduced the exposure compared to the other ABDEG-like116329912564Docket No. ARGX-T2501 / 01 WOmutations. Finally, also the clone influenced the PK, as OA-02A10-ABDEG had a better exposure compared to OA-05A01-ABDEG (FIG. 5).

[0334] PD effect of the OA IgG sweeping antibodies with different FcRn affinities was evaluated on clearance of total IgG (preloaded huIVIg). The measured concentrations during the course of the study were plotted as total concentrations (FIG. 6A) and percentage to pre-dose (5min prior to test article injection, FIG.6B) per treatment group. From dosing group OA-02A10-LALAPG-ABDEG, mouse 4 was not preloaded with IVIg and huIgGl tracer, and thus excluded from the PD analysis. Mouse 2 from dosing group OA-02A10-YPY was underdosed but shows a similar normalized IVIg PD profile and was therefore included in the analysis of the PK profiles.

[0335] A PD effect was observed for all molecules, with all molecules enhancing huIgG reduction compared to the control PBS group, while all OA-IgG-sweepers except for OA-02A10-YY outcompeted the benchmark ARGX-113 group. Indeed, both OA-02A10-ABDEG and OA-2A10-YPY resulted in a ±90% reduction in huIgGs after 2 days. OA-02A10-LALAPG-ABDEG reduced preloaded hlgGl by more than 90% after 2 days and almost completely after 1 week. OA-05A10-ABDEG resulted in a very strong reduction of preloaded huIgGs to more than 90% in the first day, and more than 99% after 2 days, confirming previous results seen in Study 1. Similar results were shown when measuring clearance of huIgGl tracer (data not shown).

[0336] To evaluate a potential impact of test articles on endogenous levels of HSA in Albumus RaglKO mice, the sera sampled throughout the study were analyzed in HSA-specific ELISA. The measured concentrations were plotted as total concentrations and as percentage to pre-dose (day 0, -5min) per treatment group. All test items, including ARGX-113, showed HSA concentrations equal to or above the PBS group, so no decrease in serum albumin levels was observed with the tested molecules over the course of the study (data not shown).Conclusions

[0337] In the first study, pH-dependent binding to IgGs was shown to enhance IgG reduction, indicated by the comparison between anti-IgG clones 01 A07, 02A10, and 05A01 in an OA-ABDEG format. This difference was only seen for the strong pH-dependent clone 05A01, but not for 02A10 and 01A07, which both outcompeted the control OA-mAb37-ABDEG. Note that clone 02A10 has a better PK than clones 05A01 and 01A07, indicating that Fab characteristics also play a role in exposure.117329912564Docket No. ARGX-T2501 / 01 WO

[0338] In the second study, increased affinity for FcRn at pH 7.4 was shown to be important for IgG sweeping, although this seems to be finite and a plateau is reached. Indeed, OA-02A10-YY, which has a lower affinity for FcRn at pH 7.4, did not result in a better IgG reduction than efgartigimod (ARGX-113). When comparing OA-02A10-ABDEG and OA-02A10-YPY, both molecules resulted in a similar PD effect, while the higher affinity for FcRn by the YPY mutation negatively influenced the PK of the molecule. This is indicative of a balance between sufficient FcRn affinity for proper sweeping, while retaining sufficient exposure. No negative effect by the test items with different FcRn affinities on the HSA levels was seen.

[0339] In addition, an unexpected but positive influence of LALAPG was seen in both PD and PK of the OA-02A10-LALAPG-ABDEG. The LALAPG mutation is an Fc silencing mutation for the effector function of IgG, as it prevents interactions with FcyRs and Clq, with unaffected FcRn interaction and Fc stability. This confirms that FcyRs play a role in the uptake of the test item and that IgG:test item stoichiometry might have an influence. Indeed, a link between the long PK and the positive PD effect of OA-02A10-LALAPG-ABDEG might be present.

[0340] In conclusion, both pH-dependent binding of the Fab to IgGs and the increased affinity for FcRn at both pH 7.4 and 6 are important for IgG sweeping combined with reduced Fc effector function.Example 4: Impact of LALAPG on IgG sweeping

[0341] This study aimed to confirm the positive effect on PK and PD in hFcRn / hFcgR mice by knocking-out the effector functions with the LALAPG-mutations in the anti-IgG OA-O2A10-ABDEG molecule.

[0342] For this experiment, mixed gender hFcyR and hFcRn knock-in (K.I.) mice received a mix of intravenous immunoglobulin (IVIg, 200mg / kg) and huIgGl tracer (20 mg / kg) intraperitoneally 3 days prior to injection of the test items (day - 3). On day 0, the mice received one of the compounds once intravenously (IV) through the tail vein at a dose of 40 mg / kg.

[0343] A control group was IV injected with PBS. All animals were pre-weighed before dosing and dosed according to their body weights according to the groups, doses, and bleeding scheme described in Table 19.Table 19: Groups and dosing regimen118329912564Docket No. ARGX-T2501 / 01 WOResults

[0344] To evaluate the PK profiles of the test articles after a single IV administration, their concentrations in mouse serum were determined during the course of the study according to the bleeding scheme in Table 19. The obtained values were plotted in pg / mL. The results indicate a higher exposure of OA-02A10-LALAPG-ABDEGthan OA-02A10-ABDEG (FIG. 7).

[0345] PD effects of 40 mg / kg OA-02A10-ABDEG and OA-02A10-LALAPG-ABDEG were evaluated on clearance of total huIgG (preloaded huIVIg). The measured concentrations during the course of the study were plotted as total concentrations (FIG. 8A) and as a percentage to pre-dose (2h prior to test article injection) (FIG. 8B). Two mice in dosing group OA-02A10-ABDEG were not properly preloaded with IVIg. These mice were excluded from FIGs. 8A-8B.Although one mouse in OA-02A10-LALAPG-ABDEG dosing group was not properly dosed, the IVIg PD result were in line with the other mice of this dosing group and thus included in FIGs.8A-8B

[0346] APD effect was observed for both OA-02A10-ABDEGand OA-02A10-LALAPG-ABDEG, when compared to the PBS group. Although both molecules were injected at the same dose of 20 mg / kg, a longer and deeper reduction of huIgG was seen when the molecule includes the LALAPG mutations, confirming the importance of Fc effector function abrogation for IgG-sweeping.Conclusion

[0347] The aim of this study was to confirm the positive effect on PK and PD of the LALAPG mutations in the anti-IgG OA-02A10-ABDEG molecule in hFcRn / hFcgR mice. Here, we confirm previous results from Albumus RaglKO mice and underline the importance of Fc effector function abrogation for IgG-sweeping in mice expressing both hFcRn and hFcyRs. Both PK and PD improved by including the LALAPG mutation, when directly comparing OA-02A10-119329912564Docket No. ARGX-T2501 / 01 WOABDEG and OA-02A10-LALAPG-ABDEG. Similar results were obtained when comparing OA-05A01-ABDEG and OA-05A01-LALAPG-ABDEG, suggesting the effect of LALAPG is not clone-specific (data not shown).Example 5: Characterization of humanized, pH-dependent IgG sweeping antibody variants

[0348] In vitro characterization of humanized variants of the anti-IgG ABDEG™ antibody OA-02A10-LALAPG-ABDEG with increased pH dependency and removed deamidation and / or oxidation sites was explored. In vivo drug exposure and IgG sweeping efficacy of the OA-anti-IgG variants was also performed to identify variants for further study of safety and efficacy in cynomolgus monkeys.Results

[0349] The closest human germline of parental llama-derived anti-IgG clone 02A10 was identified. Point mutations were incorporated in the parental VH and VL domains, focusing on the framework (FW) regions, to increase the percentage sequence identity in the framework regions above a threshold of 95%. Four germlined VH were combined with 8 germlined VH and resulting combinations screened for IgGl binding at 7.4 and 6.0 and IgG3 binding at pH 7.4. Only slight differences in affinity values to huIgGl at pH 7.4 were observed between the different germlined combinations, with KD values ranging from 9.3 to 16.1 nM. The KD values indicated the affinity to huIgGl at pH 6.0 ranged from 90 to 269 nM. The pH-dependency was characterized by the ratio of the KD at pH 6.0 to the KD at pH 7.4, which was slightly higher or lower compared to the parental 02A10 clone depending on the germline combination. The binding to huIgG3 was retained for all 02A10 germline combinations at pH 7.4. A summary of these results is provided in Table 20. The combination of 02A10 VH JV1 VL KV1 (“02A10 GL”) showed a slightly higher affinity and pH dependency compared to parental 02A10, while having a higher percentage sequence identity to its closest human germlines and was chosen for further modification.120329912564Docket No. ARGX-T2501 / 01 WO Table 20: Germline Fab screening for IgG binding affinity121329912564Docket No. ARGX-T2501 / 01 WO122329912564Docket No. ARGX-T2501 / 01 WO

[0350] The germlined 02A10 variant, 02A10 GL, was further engineered with a dual aim: (1) increase pH dependency by His engineering; and (2) removal of liability motifs that could result in post-translational modifications.

[0351] His engineering was performed by substituting a single residue of the CDRs to a Histidine. This was done for both the VL (33 mutants) and the VH (40 mutants), giving a total of 73 single His-mutants. Subsequently, these mutants were produced (24-well productions) and screened for binding to IgGl at pH 7.4 and pH 6.0. Some variants were excluded from further study. Of the remaining variants, 1 His variant per CDR of the VL were selected for further study (Hisl = His-engineering in VL CDR1; His2 = His-engineering in VL CDR2; and His3 = His-engineering in VL CDR3).

[0352] Next, 15 VH variants were produced with mutations aimed to remove liability motifs and combined with the 3 VL His variants described above. These were produced with the VL of 02A10 GL and characterized for their binding to huIgGl and hu!gG3. Simultaneously, 3 His-engineered variants of the VL were produced together with the VH of 02 Al 0_GL and screened for huIgGl and hu!gG3 binding.

[0353] All His variants retained binding to huIgGl at both pH 7.4 and pH 6.0. Out of the 3 His-engineered variants of the VL, the GLHis3 variant showed the highest KD values (lower affinity) values at both pH 7.4 and pH 6.0 compared to the parental 02A10 Fab. This variant resulted in the highest pH-dependency ratio of KD values. The huIgG3 binding of these His variants remained similar to the parental 02A10 Fab, with the GLHis3 variant again resulting in a slightly higher KD value.

[0354] GLLiab4, GLLiab7, GLLiab9 and GLLiabll demonstrated binding to huIgGl at pH 7.4 with a similar to slightly reduced affinity as compared to the parental 02A10 Fab, while the kinetic constants for binding to huIgGl at pH 6.0 could often not be determined or showed reduced binding at pH 6.0 (Table 21).

[0355] Three IgG binding liability variants of the VH (GLLiab4, GLLiab9 and GLLiab 11) were further combined with three His variants of the VL (GLHisl, GLHis2 and GLHis3). The production yields and quality were characterized during a production on 50 mL scale. A difference in productivity between His variants combined with the same VH was observed, where Hisl variants showed superior yields compared to His2 and His3 variants. At the same time, a minor123329912564Docket No. ARGX-T2501 / 01 WOdifference in purity between His variants could be observed, with slightly higher amounts of impurities for Hisl variants.

[0356] The surface bound affinity and pH-dependent binding profile of the liability / histidine variants of 02A10 were evaluated for binding to huIgGl, hu!gG2, hu!gG3, hu!gG4, cyno IgG, rabbit IgG, IgG4_LALA-NHance, and Fc-ABDEG (efgartigimod) by SPR using Biacore 8K+ with a single cycle kinetics protocol. A summary of the kinetic screening of these liability / histidine variants can be found in Table 22.

[0357] Three double mutants were produced and characterized by SPR for their affinity and pH-dependent binding profile to the different IgGs, as described above: OA-02A10-GLLiab4 / l I Hisl-LALAPG-ABDEG, OA-02A10-GLLiab9 / l I Hisl-LALAPG-ABDEG, and OA-02A10-GLLiab9 / ll_His3-LALAPG-ABDEG.

[0358] A summary of the kinetic screening of these liability / histidine variants can be found in Table 23.124329912564Docket No. ARGX-T2501 / 01 WOTable 21: Human IgGl / IgG3 binding affinity of 02A10 GL variantsN / A = kinetic constants out of instrument’s specifications or could not be uniquely determined; nd = Rmax < 10RU125329912564Docket No. ARGX-T2501 / 01 WOTable 22: Binding affinity of liability / histidine 02A10 GL variants for different IgG subclasses and variants126329912564Docket No. ARGX-T2501 / 01 WO127329912564Docket No. ARGX-T2501 / 01 WO128329912564Docket No. ARGX-T2501 / 01 WO129329912564Docket No. ARGX-T2501 / 01 WON / A = kinetic constants out of instrument’s specifications or could not be uniquely determined; nd = Rmax < 10RU; *Rmax values overestimated130329912564Docket No. ARGX-T2501 / 01 WOTable 23: Binding affinity of OA-02A10 GL LALAPG-ABDEG double mutant variants for different IgG subclasses and variants131329912564Docket No. ARGX-T2501 / 01 WO132329912564Docket No. ARGX-T2501 / 01 WON / A = kinetic constants out of instrument’s specifications or could not be uniquely determined; ur = unreliable 1:1 fitting (very high Chi2)133329912564Docket No. ARGX-T2501 / 01 WO

[0359] FcRn binding capacity of the liability / histidine 02A10 variants were assessed by means of ELISA at pH 7.4 and pH 6.0. All variants contain the LALAPG- and ABDEG-mutations, for which the latter is known to result in increased affinity to FcRn at both pH 7.4 and pH 6.0. Indeed, all test compounds bound with nM affinity to FcRn, with the highest affinity (lowest EC50-value) at pH 6.0. No distinction between the variants could be made. EC50 values are reported in Table 24Table 24: Calculated EC50 values derived from FcRn binding assay of liability / histidine 02A10 variants at pH 7.4 and pH 6.0

[0360] FcRn occupancy of the liability / histidine variants of 02A10 with and without complexing of IVIg was evaluated on U937 cells. For comparison, the parental OA-02A10-LALAPG-ABDEG and efgartigimod were also analyzed. Efgartigimod had a better occupancy compared to the OA-02A10-GL antibodies, as expected due to its smaller size. The IC50-values in Table 25 demonstrate that the OA-02A10-GL variants occupy FcRn slightly less in complex with IVIg compared to the antibodies without complex.Table 25: Calculated IC50-values derived from FcRn occupancy assay of liability / histidine 02A10 variants134329912564Docket No. ARGX-T2501 / 01 WO

[0361] The amount of FcRn degradation due to anti-IgG antibodies was assessed, with and without complexing with IVIg (Table 26). Anti-FcRn mAh 1 was included as a positive control. As expected, anti-FcRn mAbl induced up to 84% FcRn degradation. All OA-02A10-GL variants showed no FcRn degradation, independent of being in complex with IVIg.Table 26: FcRn degradation in HEK WT FcRn-GFP cells

[0362] The dissociation rate constant of the liability / histidine variants of 02A10 for binding to Fc hlgGl-WT was evaluated by SPR with a MCK protocol with Biacore 8K+. Briefly, Fc hlgGl-WT was immobilized with a low coating density, prior to injecting the liability / histidine variants of 02A10 in a dilution series from 1.56 nM to 50 nM, with the association phase at pH 7.4 and the dissociation phase at pH 6.0. Data were analyzed using the multi cycle kinetics predefined evaluation method of the Biacore™ Insight Evaluation Software. Kinetic parameters were calculated using the 1:1 binding model. Data are shown in FIG. 9. All liability / histidine variants of 02A10 showed improved dissociation from Fc hlgGl-WT compared to the parental OA-02A10-LALAPG-ABDEG, reflecting the improvement in pH-dependency.

[0363] An in vivo study using IVIg preloaded Albumus RaglKO mice was conducted to assess PK and PD of the liability / histidine variants of 02A10. Briefly, mixed gender 13-17-week-old animals were preloaded with IVIg (200 mg / kg) and huIgGl tracer (20 mg / kg) through IP injection, followed by a single dose (4 mg / kg) with one of the below mentioned test articles (Table 27) through IV injection in the tail vein. Blood was collected through a different tail vein at different time points for PK / PD assessment. The huIgGl tracer was included in this study as a backup in case the IVIg tracer was not functional. Since no problems were observed with the IVIg tracer, the huIgGl tracer was not analyzed.Table 27: Groups and dosing regimen135329912564Docket No. ARGX-T2501 / 01 WO

[0364] To assess the PK profiles of the test articles after a single IV administration, their levels in mouse serum were determined during the course of the study according to the bleeding scheme in Table 27. Serum concentrations of the different test articles are plotted in pg / mL as mean ± SD of 3-5 animals per group over time, during the course of the study (FIG. 10). All variants show similar exposure with comparable PK profiles to the parental O A-02 A 10-LAL APG-ABDEG.

[0365] To assess the pharmacodynamic effect of the test articles on tracer human intravenous immunoglobulin (IVIg) after a single IV administration, the levels of human IVIg in mouse serum were determined during the study, following the bleeding scheme in Table 27. The anti-kappa human light chain ELISA was used, opposite to the light chain type of the test article.

[0366] All variants showed faster and deeper IgG degradation compared to the parental OA-02A10-LALAPG-ABDEG (FIG. 11A-11B). Of these liability / histidine variants, GLLiab4_Hisl, GLLiab4 / l I Hisl, GLLiab9_His3 and GLLiab9 / l l_His3 showed the most rapid 136329912564Docket No. ARGX-T2501 / 01 WOand strong IgG reduction. When observing the PD profile of each mouse per group, no signal could be detected in mouse 118504 (OA-02A10-GLLiab9 / Liabll_Hisl-LALAPG-ABDEG) and 118480 (OA-02A10-GLLiab9_Hisl-LALAPG-ABDEG), presumably due to a problem in administration. Hence, the data was excluded from FIG. 11A-11B.Example 6: PK / PD Study in cynomolgus monkeys

[0367] Four groups of cynomolgus monkeys received a single IV administration of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG. Each group consisted of one male and one female. Group 1 received a dose of 0.25 mg / kg, group 2 received a dose of 2.5 mg / kg, group 3 received a dose of 10 mg / kg, and group 4 received a dose of 100 mg / kg.

[0368] To assess the PK profile of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG after a single IV administration, serum levels were determined over the 8-week course of the study. Serum concentrations of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG are plotted in pg / mL as mean per group over time, during the course of the study (FIG. 12A). PK was dose-dependent, with rapid exposure decreases observed at all doses, likely due to ADA.

[0369] To assess the pharmacodynamic effect of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG on serum IgG after a single IV administration, the serum IgG levels were determined over the 8-week course of the study. The percentage IgG compared to baseline serum IgG levels are plotted over time in FIG. 12B.

[0370] Serum IgG levels decreased in a dose-dependent manner after a single dose of 0.25, 2.5, 10, or 100 mg / kg OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG to minimal IgG concentrations (Rmin) of 77-78%, 53-56%, 26-35%, or 14-18% of predose, respectively. Rmin was reached at Tmin of 3 days after dosing of 0.25 mg / kg, 7-9 days after dosing of 2.5 or 10 mg / kg or 3-7 days after dosing of 100 mg / kg. Thereafter IgG concentrations increased again and reached predose concentrations within approximately 14 days after 0.25 or 2.5 mg / kg, 21 days after 10 mg / kg or 28 days after 100 mg / kg of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG.Example 7: Binding of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG to IgG subclasses

[0371] Binding affinity of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG to different IgG subclasses and allotypes at pH 7.4 and pH 6.0 was measured by SPR with Biacore 8k+. Briefly, various IgGs were immobilized prior to injecting OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG 137329912564Docket No. ARGX-T2501 / 01 WOin a dilution series from 7.81 nM to 1000 nM, with the association phase at pH 7.4 and the dissociation phase at pH 6.0. Kinetic parameters were calculated using the 1 : 1 binding model. Data are shown in FIG. 13. The KD values represent the mean of 3 independent runs ± standard deviation.

[0372] OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG bound to all tested IgG subclasses and allotypes, with a reduced affinity to IgG3-R435.Example 8: IgG3 sweeping by OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG

[0373] This study aims to assess the ability of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG to sweep IgG3 allotypes containing R435.

[0374] A cross-study comparison between equimolar doses of ARGX-113 (20 mg / kg) and OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG (40 mg / kg) was performed. In both studies, Tg32 SCID mice (hFcRn+) received intravenous immunoglobulin (IVIg, 200mg / kg) 2 days prior to injection of the test items (day -2), and were also implanted subcutaneously with an IVIg-loaded osmotic Alzet pump to provide continuous release of IVIg throughout the study. On day 0, the mice received one of the compounds once intravenously (IV) through the tail vein at a dose of either 40 mg / kg (OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG) or 20 mg / kg (ARGX-113).

[0375] A control group in each study was IV injected with PBS. All animals were preweighed before dosing and dosed according to their body weights according to the groups, doses, and bleeding scheme described in Table 28.Table 28: Groups and dosing regimen138329912564Docket No. ARGX-T2501 / 01 WO

[0376] To evaluate the PK profiles of the test articles after a single IV administration, their concentrations in mouse serum were determined during the course of the study according to the bleeding scheme in Table 28. The obtained values were plotted in pg / mL. The results indicate a higher exposure of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG than ARGX-113 (FIG. 14B).

[0377] PD effects of equimolar doses of ARGX-113 and OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG were evaluated on clearance of the IgG3-R435 component of IVIg. The measured concentrations during the course of the study were plotted as a percentage to pre-dose (Ih prior to test article injection) (FIG. 14A).

[0378] A PD effect was observed for both ARGX-113 and OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG, when compared to the PBS group. Although both molecules were injected at equimolar doses, a faster and deeper reduction of IgG3-R435 is seen with OA-02A10-GLLiab4-Hi s 1 -L ALAPG- ABDEG.

[0379] To confirm that the enhanced reduction of IgG3-R435 is due to sweeping instead of higher exposure of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG compared to ARGX-113, a further study was conducted to compare OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG with OA-02A10-GLLiab5-Hisl -LALAPG-ABDEG.

[0380] In this study, AlbuMus RaglKO mice received a mix of intravenous immunoglobulin (IVIg, 200mg / kg) and IgG3 tracer (20 mg / kg) intravenously 3 days prior to injection of the test items (day -3). On day 0, the mice received one of the compounds once intravenously (IV) through the tail vein at a dose of either 4 mg / kg or 15 mg / kg.

[0381] A control group was IV injected with PBS. All animals were pre-weighed before dosing and dosed according to their body weights according to the groups, doses, and bleeding scheme described in Table 29.Table 29: Groups and dosing regimen139329912564Docket No. ARGX-T2501 / 01 WO

[0382] To evaluate the PK profiles of the test articles after a single IV administration, their concentrations in mouse serum were determined during the course of the study according to the bleeding scheme in Table 29. The obtained values were plotted in pg / mL. As expected, the results indicate a similar exposure of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG and OA-02A10-GLLiab5-Hisl-LALAPG-ABDEG (FIG. 15C).

[0383] PD effects of OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG and OA-02A10-GLLiab5-Hisl-LALAPG-ABDEG were evaluated on clearance of both total IgG (IVIg) and tracer IgG3-R435. The measured concentrations during the course of the study were plotted as a percentage to pre-dose (Ih prior to test article injection) (FIGs. 15A-15B).

[0384] A PD effect was observed for OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG, when compared to the PBS group and OA-02A10-GLLiab5-Hisl-LALAPG-ABDEG. OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG resulted in a dose-dependent reduction of both IVIg and IgG3-R435 that was both deeper and faster than that exhibited with either the PBS or with OA-02A10-GLLiab5-Hisl-LALAPG-ABDEG. Since exposure of both test compounds was similar, these data confirm that OA-02A10-GLLiab4-Hisl-LALAPG-ABDEG is able to sweep IgG3-R435.***

[0385] The invention is not to be limited in scope by the specific embodiments described herein. Indeed, various modifications of the invention in addition to those described will become apparent to those skilled in the art from the foregoing description and accompanying figures. Such modifications are intended to fall within the scope of the appended claims.140329912564

Claims

Docket No. ARGX-T2501 / 01 WOCLAIMS1. An IgG-binding molecule comprising an IgG-binding domain, wherein the IgG-binding domain:a) specifically binds to human IgGl, human IgG2, human IgG3, or human IgG4, and b) does not specifically bind to the amino acid sequence set forth in SEQ ID NO: 1.

2. The IgG-binding molecule of claim 1, wherein the IgG-binding domain specifically binds to the amino acid sequence of SEQ ID NO: 454, 455, 456, or 457.

3. The IgG-binding molecule of claim 2, wherein the IgG-binding domain specifically binds to the amino acid sequence of SEQ ID NO: 454, 455, 456, and 457.

4. The IgG-binding molecule of any one of the preceding claims, wherein the IgG-binding domain has a higher affinity for human IgGl, human IgG2, human IgG3, or human IgG4 at pH 7.4 than at pH 5.5.

5. An IgG-binding molecule comprising an IgG-binding domain, wherein the IgG-binding domain specifically binds to human IgGl, human IgG2, human IgG3, or human IgG4 with higher affinity at pH 7.4 than at pH 5.5.

6. The IgG-binding molecule of any one of the preceding claims, wherein the IgG-binding domain specifically binds to human IgGl, human IgG2, human IgG3, and human IgG4.

7. The IgG-binding molecule of any one of the preceding claims, wherein the IgG-binding domain has a higher affinity for human IgGl at pH 7.4 than at pH 5.5.

8. The IgG-binding molecule of any one of the preceding claims, wherein the IgG-binding domain has a higher affinity for human IgGl, human IgG2, and human IgG4 at pH 7.4 than at pH 5.5.141329912564Docket No. ARGX-T2501 / 01 WO9. The IgG-binding molecule of any one of the preceding claims, wherein the IgG-binding domain has a higher affinity for human IgGl, human IgG2, human IgG3, and human IgG4 at pH 7.4 than at pH 5.5.

10. The IgG-binding molecule of any one of the preceding claims, wherein the ratio of KD for IgG at pH 5.5 and KD for IgG at pH 7.4 is at least 2.

11. The IgG-binding molecule of any one of the preceding claims, wherein the IgG-binding domain specifically binds to IgG with nanomolar affinity at pH 7.4 and does not specifically bind to IgG at pH 5.5.

12. The IgG-binding molecule of any one of the preceding claims, wherein the IgG-binding domain comprises:(a) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 428, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 451;(b) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 357, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 389;(c) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 358, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 390;(d) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 359, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 391;(e) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 360, and a VL comprising CDRL1,142329912564Docket No. ARGX-T2501 / 01 WOCDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 392;(f) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 361, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 393;(g) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 362, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 394;(h) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 363, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 395;(i) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 364, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 396;(j) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 365, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 397;(k) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 366, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 398;(l) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 367, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 399;143329912564Docket No. ARGX-T2501 / 01 WO(m) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 368, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 400;(n) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 369, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 401;(o) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 370, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 402;(p) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 371, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 403;(q) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 372, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 404;(r) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 373, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 405;(s) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 374, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 406;(t) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 375, and a VL comprising CDRL1,144329912564Docket No. ARGX-T2501 / 01 WOCDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 407;(u) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 376, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 408;(v) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 377, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 409;(w) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 378, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 410;(x) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 379, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 411;(y) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 380, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 412;(z) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 381, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 413;(aa) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 382, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 414;145329912564Docket No. ARGX-T2501 / 01 WO(bb) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 383, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 415;(cc) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 384, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 416;(dd) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 385, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 417;(ee) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 386, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 418;(ff) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 387, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 419; or(gg) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 388, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 420.

13. An IgG-binding molecule that specifically binds to human IgG, comprising an IgG-binding domain comprising:(a) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 428, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 451;146329912564Docket No. ARGX-T2501 / 01 WO(b) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 357, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 389;(c) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 358, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 390;(d) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 359, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 391;(e) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 360, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 392;(f) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 361, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 393;(g) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 362, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 394;(h) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 363, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 395;(i) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 364, and a VL comprising CDRL1,147329912564Docket No. ARGX-T2501 / 01 WOCDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 396;(j) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 365, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 397;(k) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 366, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 398;(l) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 367, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 399;(m) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 368, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 400;(n) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 369, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 401;(o) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 370, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 402;(p) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 371, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 403;148329912564Docket No. ARGX-T2501 / 01 WO(q) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 372, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 404;(r) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 373, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 405;(s) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 374, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 406;(t) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 375, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 407;(u) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 376, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 408;(v) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 377, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 409;(w) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 378, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 410;(x) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 379, and a VL comprising CDRL1,149329912564Docket No. ARGX-T2501 / 01 WOCDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 411;(y) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 380, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 412;(z) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 381, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 413;(aa) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 382, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 414;(bb) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 383, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 415;(cc) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 384, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 416;(dd) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 385, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 417;(ee) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 386, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 418;150329912564Docket No. ARGX-T2501 / 01 WO(ff) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 387, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 419; or(gg) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 388, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 420.

14. The IgG-binding molecule of claim 12 or 13, wherein the CDRH1, CDRH2, CDRH3, CDRL1, CDRL2, and CDRL3 amino acid sequences, respectively, comprise the amino acid sequences set forth in SEQ ID NOs: 183, 184, 185, 348, 349, and 350; 69, 70, 71, 225, 226, and 227; 72, 73, 74, 228, 229, and 230; 75, 76, 77, 231, 232, and 233; 78, 79, 80, 234, 235, and 236; 81, 82, 83, 237, 238, and 239; 84, 85, 86, 240, 241, and 242; 87, 88, 89, 243, 244, and 245; 90, 91, 92, 246, 247, and 248; 93, 94, 95, 249, 250, and 251; 96, 97, 98, 252, 253, and 254; 99, 100, 101, 255, 256, and 257; 102, 103, 104, 258, 259, and 260; 105, 106, 107, 261, 262, and 263; 108, 109, 110, 264, 265, and 266; 111, 112, 113, 267, 268, and 269; 114, 115, 116, 270, 271, and 272; 117, 118, 119, 273, 274, and 275; 120, 121, 122, 276, 277, and 278; 123, 124, 125, 279, 280, and 281; 126, 127, 128, 282, 283, and 284; 129, 130, 131, 285, 286, and 287; 132, 133, 134, 288, 289, and 290; 135, 136, 137, 291, 292, and 293; 138, 139, 140, 294, 295, and 296; 141, 142, 143, 297, 298, and 299; 144, 145, 146, 300, 301, and 302; 147, 148, 149, 303, 304, and 305; 150, 151, 152, 306, 307, and 308; 153, 154, 155, 309, 310, and 311; 156, 157, 158, 312, 313, and 314; 159, 160, 161, 315, 316, and 317; or 162, 163, 164, 318, 319, and 320.

15. The IgG-binding molecule of any one of claims 12-14, wherein the VH comprises an amino acid sequence at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence set forth in any one of SEQ ID NOs: 357-388 and 422-441.

16. The IgG-binding molecule of any one of claims 12-15, wherein the VH comprises an amino acid sequence set forth in any one of SEQ ID NOs: 357-388 and 422-441.151329912564Docket No. ARGX-T2501 / 01 WO17. The IgG-binding molecule of any one of claims 12-16, wherein the VL comprises an amino acid sequence at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence set forth in any one of SEQ ID NOs: 389-420 and 443-453.

18. The IgG-binding molecule of any one of claims 12-17, wherein the VL comprises an amino acid sequence set forth in any one of SEQ ID NOs: 389-420 and 443-453.

19. The IgG-binding molecule of any one of claims 12-18, wherein the VH and VL, respectively, comprise the amino acid sequences set forth in SEQ ID NOs: 428 and 451, 357 and 389, 358 and 390, 359 and 391, 360 and 392, 361 and 393, 362 and 394, 363 and 395, 364 and 396, 365 and 397, 366 and 398, 367 and 399, 368 and 400, 369 and 401, 370 and 402, 371 and 403, 372 and 404, 373 and 405, 374 and 406, 375 and 407, 376 and 408, 377 and 409, 378 and 410, 379 and 411, 380 and 412, 381 and 413, 382 and 414, 383 and 415, 384 and 416, 385 and 417, 386 and 418, 387 and 419, or 388 and 420, respectively.

20. The IgG-binding molecule of any one of the preceding claims, wherein the IgG-binding domain is a Fab.

21. The IgG-binding molecule of claim 20, wherein the Fab comprises a human IgG CHI domain.

22. The IgG-binding molecule of claim 21, wherein the human IgG CHI domain comprises the amino acid sequence set forth in SEQ ID NO: 33.

23. The IgG-binding molecule of claims 21 or 22, wherein the Fab comprises a human light chain constant domain.

24. The IgG-binding molecule of claim 23, wherein the human light chain constant domain comprises the amino acid sequence set forth in SEQ ID NO: 46.152329912564Docket No. ARGX-T2501 / 01 WO25. The IgG-binding molecule of any one of the preceding claims, further comprising a means for binding to FcRn with higher affinity at pH 7.4 relative to a wild-type Fc region.

26. The IgG-binding molecule of any one of claims 13-25, which does not specifically bind to the amino acid sequence set forth in SEQ ID NO: 1.

27. The IgG-binding molecule of any one of claims 13-26, which specifically binds to human IgGl, human IgG2, human IgG3, and human IgG4.

28. The IgG-binding molecule of any one of claims 13-27, which has a higher affinity for human IgGl, human IgG2, human IgG3, or human IgG4 at pH 7.4 than at pH 5.5.

29. The IgG-binding molecule of any one of claims 13-28, which has a higher affinity for human IgGl, human IgG2, and human IgG4 at pH 7.4 than at pH 5.5.

30. The IgG-binding molecule of any one of claims 13-29, which has a higher affinity for human IgGl, human IgG2, human IgG3, and human IgG4 at pH 7.4 than at pH 5.5.

31. The IgG-binding molecule of any one of the preceding claims, further comprising a variant Fc region that binds to FcRn with higher affinity at pH 7.4 relative to the corresponding wild-type Fc region.

32. An IgG-binding molecule comprising: a means for binding to human IgGl, human IgG2, human IgG3, or human IgG4; and a variant Fc region that binds to FcRn with higher affinity at pH 7.4 relative to the corresponding wild-type Fc region.

33. The IgG-binding molecule of claim 32, which does not specifically bind to the amino acid sequence set forth in SEQ ID NO: 1.153329912564Docket No. ARGX-T2501 / 01 WO34. The IgG-binding molecule of claim 32 or 33, which specifically binds to human IgGl, human IgG2, human IgG3, and human IgG4.

35. The IgG-binding molecule of any one of claims 32-34, which has a higher affinity for human IgGl, human IgG2, human IgG3, or human IgG4 at pH 7.4 than at pH 5.5.

36. The IgG-binding molecule of any one of claims 32-35, which has a higher affinity for human IgGl, human IgG2, and human IgG4 at pH 7.4 than at pH 5.5.

37. The IgG-binding molecule of any one of claims 32-36, which has a higher affinity for human IgGl, human IgG2, human IgG3, and human IgG4 at pH 7.4 than at pH 5.5.

38. The IgG-binding molecule of any one of claims 31-37, wherein the variant Fc region is a variant IgGl Fc region.

39. The IgG-binding molecule of any one of claims 31-38, wherein the variant Fc region binds to FcRn at pH 6.0 with an affinity that is at least 20 times greater than the affinity of the corresponding wild-type human IgG Fc region for FcRn.

40. The IgG-binding molecule of any one of claims 31-39, wherein the variant Fc region binds to FcRn at pH 6.0 with a KD or 15 nM or less.

41. The IgG-binding molecule of any one of claims 31-40, wherein the variant Fc region comprises a first Fc domain and a second Fc domain which form a dimer, wherein the first Fc domain and the second Fc domain comprise amino acids Y, T, E, K, F, and Y at EU positions 252, 254, 256, 433, 434, and 436, respectively.

42. The IgG-binding molecule of any one of claims 31-41, wherein the variant Fc region comprises one or more mutations that reduce or eliminate Fc effector function.154329912564Docket No. ARGX-T2501 / 01 WO43. The IgG-binding molecule of claim 41 or 42, wherein the first Fc domain and / or the second Fc domain comprise amino acids A and A at EU positions 234 and 235.

44. The IgG-binding molecule of claim 43, wherein the first Fc domain and / or the second Fc domain comprise amino acid G or A at EU position 329.

45. The IgG-binding molecule of any one of claims 41-44, wherein the first Fc domain and the second Fc domain comprise amino acids A, A, Y, T, E, G, K, F, and Y, at EU positions 234, 235, 252, 254, 256, 329, 433, 434, and 436, respectively.

46. The IgG-binding molecule of any one of claims 41-45, wherein the variant Fc region comprises one or more mutations that promote dimerization between the first Fc domain and the second Fc domain.

47. The IgG-binding molecule of claim 46, wherein the first Fc domain and the second Fc domain comprise knob-into-holes amino acid mutations.

48. The IgG-binding molecule of any one of claims 41-47, wherein the first Fc domain comprises amino acid W at EU position 366, and wherein the second Fc domain comprises amino acids S, A, and V at EU positions 366, 368, and 407, respectively.

49. The IgG-binding molecule of any one of claims 41-48, wherein:(a) the first Fc domain comprises amino acids A, A, Y, T, E, G, W, K, F, and Y at EU positions 234, 235, 252, 254, 256, 329, 366, 433, 434, and 436, respectively, and(b) the second Fc domain comprises amino acids A, A, Y, T, E, G, S, A, V, K, F, and Y at EU positions 234, 235, 252, 254, 256, 329, 366, 368, 407, 433, 434, and 436, respectively.

50. The IgG-binding molecule of any one of claims 41-49, wherein the IgG-binding domain is linked to the N-terminus of the first Fc domain.155329912564Docket No. ARGX-T2501 / 01 WO51. The IgG-binding molecule of any one of claims 41-50, wherein the first Fc domain comprises or consists of the amino acid sequence set forth in SEQ ID NO: 17 and / or the second Fc domain comprises or consists of the amino acid sequence set forth in SEQ ID NO: 20.

52. An IgG-binding molecule comprising an IgG-binding domain and a variant IgGl Fc region, wherein the variant IgGl Fc region comprises a first Fc domain and a second Fc domain which form a dimer, wherein the first Fc domain and the second Fc domain comprise amino acids Y, T, E, K, F, and Y at EU positions 252, 254, 256, 433, 434, and 436, respectively, and wherein the IgG-binding domain:a) specifically binds to human IgGl, human IgG2, human IgG3, or human IgG4, and b) does not specifically bind to the variant IgGl Fc region.

53. The IgG-binding molecule of claim 52, wherein the IgG-binding molecule comprises no more than one IgG-binding domain.

54. The IgG-binding molecule of claim 52 or 53, wherein the IgG-binding domain is linked to the N-terminal end of the first Fc domain.

55. The IgG-binding molecule of any one of claims 52-54, wherein the IgG-binding domain specifically binds to human IgGl, human IgG2, human IgG3, and human IgG4.

56. The IgG-binding molecule of any one of claims 52-55, wherein the IgG-binding domain has a higher affinity for human IgGl, human IgG2, human IgG3, or human IgG4 at pH 7.4 than pH 5.5.

57. The IgG-binding molecule of any one of claims 52-56, wherein the IgG-binding domain has a higher affinity for human IgGl at pH 7.4 than pH 5.5.

58. The IgG-binding molecule of any one of claims 52-57, wherein the IgG-binding domain has a higher affinity for human IgGl, human IgG2, and human IgG4 at pH 7.4 than pH 5.5.156329912564Docket No. ARGX-T2501 / 01 WO59. The IgG-binding molecule of any one of claims 52-58, wherein the IgG-binding domain has a higher affinity for human IgGl, human IgG2, human IgG3, and human IgG4 at pH 7.4 than pH 5.5.

60. The IgG-binding molecule of any one of claims 52-59, wherein the ratio of KD for IgG at pH 5.5 and KD for IgG at pH 7.4 is at least 2.

61. The IgG-binding molecule of any one of claims 52-60, wherein the IgG-binding domain specifically binds to IgG with nanomolar affinity at pH 7.4 and does not specifically bind to IgG at pH 5.5.

62. The IgG-binding molecule of any one of claims 52-61, wherein the IgG-binding domain is a Fab.

63. The IgG-binding molecule of claim 62, wherein the Fab comprises a human IgG CHI domain.

64. The IgG-binding molecule of claim 63, wherein the human IgG CHI domain comprises the amino acid sequence set forth in SEQ ID NO: 33.

65. The IgG-binding molecule of claims 63 or 64, wherein the Fab comprises a human light chain constant domain.

66. The IgG-binding molecule of claim 65, wherein the human light chain constant domain comprises the amino acid sequence set forth in SEQ ID NO: 46.

67. The IgG-binding molecule of any one of claims 52-66, wherein the IgG-binding domain comprises:(a) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 428, and a VL comprising CDRL1,157329912564Docket No. ARGX-T2501 / 01 WOCDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 451;(b) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 357, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 389;(c) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 358, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 390;(d) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 359, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 391;(e) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 360, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 392;(f) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 361, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 393;(g) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 362, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 394;(h) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 363, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 395;158329912564Docket No. ARGX-T2501 / 01 WO(i) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 364, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 396;(j) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 365, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 397;(k) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 366, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 398;(l) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 367, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 399;(m) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 368, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 400;(n) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 369, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 401;(o) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 370, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 402;(p) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 371, and a VL comprising CDRL1,159329912564Docket No. ARGX-T2501 / 01 WOCDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 403;(q) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 372, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 404;(r) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 373, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 405;(s) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 374, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 406;(t) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 375, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 407;(u) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 376, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 408;(v) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 377, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 409;(w) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 378, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 410;160329912564Docket No. ARGX-T2501 / 01 WO(x) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 379, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 411;(y) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 380, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 412;(z) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 381, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 413;(aa) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 382, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 414;(bb) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 383, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 415;(cc) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 384, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 416;(dd) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 385, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 417;(ee) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 386, and a VL comprising CDRL1,161329912564Docket No. ARGX-T2501 / 01 WOCDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 418;(ff) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 387, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 419; or(gg) a VH comprising CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 388, and a VL comprising CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ IDNO: 420.

68. The IgG-binding molecule of claim 67, wherein the CDRH1, CDRH2, CDRH3, CDRL1, CDRL2, and CDRL3 amino acid sequences, respectively, comprise the amino acid sequences set forth in SEQ ID NOs: 183, 184, 185, 348, 349, and 350; 69, 70, 71, 225, 226, and 227; 72, 73, 74, 228, 229, and 230; 75, 76, 77, 231, 232, and 233; 78, 79, 80, 234, 235, and 236; 81, 82, 83, 237, 238, and 239; 84, 85, 86, 240, 241, and 242; 87, 88, 89, 243, 244, and 245; 90, 91, 92, 246, 247, and 248; 93, 94, 95, 249, 250, and 251; 96, 97, 98, 252, 253, and 254; 99, 100, 101, 255, 256, and 257; 102, 103, 104, 258, 259, and 260; 105, 106, 107, 261, 262, and 263; 108, 109, 110, 264, 265, and 266; 111, 112, 113, 267, 268, and 269; 114, 115, 116, 270, 271, and 272; 117, 118, 119, 273, 274, and 275; 120, 121, 122, 276, 277, and 278; 123, 124, 125, 279, 280, and 281; 126, 127, 128, 282, 283, and 284; 129, 130, 131, 285, 286, and 287; 132, 133, 134, 288, 289, and 290; 135, 136, 137, 291, 292, and 293; 138, 139, 140, 294, 295, and 296; 141, 142, 143, 297, 298, and 299; 144, 145, 146, 300, 301, and 302; 147, 148, 149, 303, 304, and 305; 150, 151, 152, 306, 307, and 308; 153, 154, 155, 309, 310, and 311; 156, 157, 158, 312, 313, and 314; 159, 160, 161, 315, 316, and 317; or 162, 163, 164, 318, 319, and 320.

69. The IgG-binding molecule of claim 67 or 68, wherein the VH comprises an amino acid sequence at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence set forth in any one of SEQ ID NOs: 357-388 and 422-441.162329912564Docket No. ARGX-T2501 / 01 WO70. The IgG-binding molecule of any one of claims 67-69, wherein the VH comprises the amino acid sequence set forth in any one of SEQ ID NOs: 357-388 and 422-441.

71. The IgG-binding molecule of any one of claims 67-70, wherein the VL comprises an amino acid sequence at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence set forth in any one of SEQ ID NOs: 389-420 and 443-453.

72. The IgG-binding molecule of any one of claims 67-71, wherein the VL comprises the amino acid sequence set forth in any one of SEQ ID NOs: 389-420 and 443-453.

73. The IgG-binding molecule of claim 67, wherein:(a) the VH comprises the CDRH1, CDRH2, and CDRH3 amino acid sequences of the VH amino acid sequence set forth in SEQ ID NO: 428, and(b) the VL comprises the CDRL1, CDRL2, and CDRL3 amino acid sequences of the VL amino acid sequence set forth in SEQ ID NO: 451.

74. The IgG-binding molecule of claim 73, wherein the CDRH1, CDRH2, CDRH3, CDRL1, CDRL2, and CDRL3 amino acid sequences are set forth in SEQ ID NOs: 183, 184, 185, 348, 349, and 350, respectively.

75. The IgG-binding molecule of claim 73 or 74, wherein the VH comprises an amino acid sequence at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence set forth in SEQ ID NO: 428.

76. The IgG-binding molecule of any one of claims 73-75, wherein the VH comprises the amino acid sequence set forth in SEQ ID NO: 428.

77. The IgG-binding molecule of any one of claims 73-76, wherein the VL comprises an amino acid sequence at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least163329912564Docket No. ARGX-T2501 / 01 WO97%, at least 98%, or at least 99% identical to the amino acid sequence set forth in SEQ ID NO: 451.

78. The IgG-binding molecule of any one of claims 73-77, wherein the VL comprises the amino acid sequence set forth in SEQ ID NO: 451.

79. The IgG-binding molecule of any one of claims 52-78, wherein the variant IgGl Fc region comprises one or more mutations that reduce or eliminate Fc effector function.

80. The IgG-binding molecule of any one of claims 52-79, wherein the first Fc domain and / or the second Fc domain comprise amino acids A and A at EU positions 234 and 235.

81. The IgG-binding molecule of claim 80, wherein the first Fc domain and / or the second Fc domain comprise amino acid G or A at EU position 329.

82. The IgG-binding molecule of any one of claims 52-81, wherein the first Fc domain and the second Fc domain comprise amino acids A, A, Y, T, E, G, K, F, and Y, at EU positions 234, 235, 252, 254, 256, 329, 433, 434, and 436, respectively.

83. The IgG-binding molecule of any one of claims 52-82, wherein the variant IgGl Fc region comprises one or more mutations that promote dimerization between the first Fc domain and the second Fc domain.

84. The IgG-binding molecule of claim 83, wherein the first Fc domain and the second Fc domain comprise knob-into-holes amino acid mutations.

85. The IgG-binding molecule of any one of claims 52-84, wherein the first Fc domain comprises amino acid W at EU position 366, and wherein the second Fc domain comprises amino acids S, A, and V at EU positions 366, 368, and 407, respectively.

86. The IgG-binding molecule of any one of claims 52-85, wherein:164329912564Docket No. ARGX-T2501 / 01 WO(a) the first Fc domain comprises amino acids A, A, Y, T, E, G, W, K, F, and Y at EU positions 234, 235, 252, 254, 256, 329, 366, 433, 434, and 436, respectively, and(b) the second Fc domain comprises amino acids A, A, Y, T, E, G, S, A, V, K, F, and Y at EU positions 234, 235, 252, 254, 256, 329, 366, 368, 407, 433, 434, and 436, respectively.

87. The IgG-binding molecule of any one of claims 52-86, wherein the first Fc domain comprises or consists of the amino acid sequence set forth in SEQ ID NO: 17 and / or the second Fc domain comprises or consists of the amino acid sequence set forth in SEQ ID NO: 20.

88. The IgG-binding molecule of any one of claims 52-87, comprising a first polypeptide comprising or consisting of the amino acid sequence set forth in SEQ ID NO: 38.

89. The IgG-binding molecule of any one of claims 52-88, comprising a second polypeptide comprising or consisting of the amino acid sequence set forth in SEQ ID NO: 20.

90. The IgG-binding molecule of any one of claims 52-89, comprising a third polypeptide comprising or consisting of the amino acid sequence set forth in SEQ ID NO: 56.

91. An IgG-binding molecule comprising: a first polypeptide comprising or consisting of the amino acid sequence set forth in SEQ ID NO: 38; a second polypeptide comprising or consisting of the amino acid sequence set forth in SEQ ID NO: 20; and a third polypeptide comprising or consisting of the amino acid sequence set forth in SEQ ID NO: 56.

92. The IgG-binding molecule of any one of claims 52-91, wherein the IgG-binding molecule does not reduce serum albumin levels.

93. The IgG-binding molecule of any one of claims 52-92, wherein the IgG-binding molecule does not induce FcRn degradation.

94. An isolated polynucleotide or polynucleotides encoding the IgG-binding molecule of any one of claims 1-93.165329912564Docket No. ARGX-T2501 / 01 WO95. An expression vector comprising the isolated polynucleotide or polynucleotides of claim 94.

96. A host cell comprising the isolated polynucleotide or polynucleotides of claim 94 or the expression vector of claim 95.

97. A method for producing an IgG-binding molecule, comprising culturing the host cell of claim 96 under conditions which permit the expression of the IgG-binding molecule.

98. A composition comprising the IgG-binding molecule of any one of claims 1-93, and at least one pharmaceutically acceptable carrier.

99. An IgG-binding molecule of any one of claims 1-93 for use as a medicament.

100. A method of reducing serum IgG in a subject in need thereof comprising administering to the subject a therapeutically effective amount of the IgG-binding molecule of any one of claims 1-93, or the composition of claim 98.

101. A method of treating an antibody-mediated disorder in a subject in need thereof comprising administering to the subject a therapeutically effective amount of the IgG-binding molecule of any one of claims 1-93, or the composition of claim 98.

102. The method of claim 101, wherein the antibody -mediated disorder is an IgG-mediated disorder.

103. The method of claim 101 or 102, wherein the antibody-mediated disorder is an autoimmune disease.

104. An IgG-binding molecule of any one of claims 1-93, or a composition of claim 98, for use in the treatment of an antibody-mediated disorder.166329912564Docket No. ARGX-T2501 / 01 WO105. An IgG-binding molecule of any one of claims 1-93, for the manufacture of a medicament for treating an antibody-mediated disorder.167329912564

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