Agonistic Anti-il-2RBG heavy‑chain antibodies

Abstract

Disclosed herein are heavy-chain antibodies having activity as agonists of the dimeric interleukin‑2 receptor, pharmaceutical compositions comprising the heavy-chain antibodies, and methods of treating certain disorders, such as cancer, including but not limited to, small cell lung cancer. Also disclosed herein are methods of treating DLL3-expressing cancers comprising the administration of a T-cell engaging molecule that binds to DLL3 and an IL-2-based therapy.

Description

AGONISTIC ANTI-IL-2RBG HEAVY-CHAIN ANTIBODIESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 631,729, filed April 9, 2024, and U.S. Provisional Patent Application No. 63 / 735,080, filed December 17, 2024.SUBMISSION OF SEQUENCE LISTING

[0002] The content of the following Sequence Listing XML is incorporated herein by reference in its entirety: file name: 10880-SL-040725.xml, date created: April 7, 2025; size: 121,999 bytes.FIELD

[0003] The present disclosure provides heavy-chain antibodies having activity as agonists of the dimeric interleukin-2 (IL-2) receptor. This disclosure also provides pharmaceutical compositions comprising the heavy-chain antibodies, uses, and methods of treating certain disorders, such as cancer, including, but not limited to, DLL3 -expressing cancers, such as, for example, small cell lung cancer. Additionally, the present disclosure provides methods of treating DLL3-expressing cancers comprising the administration of a T-cell engaging molecule that binds to DLL3 (e.g., tarlatamab) and an IL-2 -based therapy, including, but not limited to, Proleukin® (aldesleukin), an IL-2 mutein, a nonet IL-2 molecule (e.g., bempegaldesleukin), or an agonistic anti-IL2RBG heavy-chain antibody disclosed herein.BACKGROUND

[0004] The pleiotropic cytokine interleukin-2 (IL-2) is a key regulator of immune cells, inducing both effector T-cell and natural killer (NK) cell proliferation, as well as the proliferation of immunosuppressive regulatory T (T-reg) cells. IL-2 therapy represents a potential strategy for transforming “cold tumors” into treatment-responsive “hot tumors” by expanding and maintaining the population of effector T-cells at a tumor site. The ability to harness the immune system against tumors has been previously established, with IL-2 being one of the first recombinant cytokine proteins to be FDA-approved for the treatment of cancer. Lotze et al., Journal of Immunology 135(4), 2865-75 (1985); Rosenberg, S. A. J Immunol 192, 5451-58 (2014). Specifically, high-dose recombinant IL-2 (Proleukin®) was developed and approved for the treatment of metastatic melanoma and metastatic renal cell carcinoma, with durable responses observed in 7-12% of patients. McDermott, D. F. et al., J Clin Oncol 23, 133-141 (2004); Payne, R. et al., J Immunother Cancer , 13 (2014); Atkins, M. B. etal., J Clin Oncol 17, 2105-2105 (1999); Rosenberg, S. A. et al., Ann Surg 22^ 307-319 (1998). However, despite having potent immune-activating activity and the potential to induce durable tumor-regression in cancer patients, the success of wild-type IL-2 cytokine as an immunotherapeutic has been limited by adverse events and poor pharmacokinetic properties. Specifically, Proleukin® is associated with severe dose-limiting toxicities, including vascular leak syndrome, hypotension, and liver toxicities. These adverse effects are believed to be driven by the preferential activation of cells, such as T-reg cells and endothelial cells, that express the high-affinity, trimeric form of the IL-2 receptor (IL-2RaPy). In contrast to the high-affinity trimeric form, the intermediate affinity dimeric form of the IL-2 receptor is only composed of the IL-2RP and IL-2Ry subunits and is expressed on resting T-cells, CD8+ memory effector T-cells, and NK cells. Choudhry, H. et al, Biomed Res Int 2018, 1-7 (2018). The IL-2Ra subunit, which is only present in the trimeric form of the IL-2 receptor, is not required for downstream JAK-STAT signaling, but its association with IL-2RP and IL-2Ry provides a 100-fold higher affinity to IL-2 compared to the heterodimeric receptor composed only of IL-2RP and IL-2Ry.SUMMARY

[0005] One aspect of the disclosure provides a heavy-chain antibody comprising an Fc region that comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, and a cysteine at position 302, all according to EU numbering.

[0006] Another aspect of the disclosure provides a heavy-chain antibody comprising a first heavy chain variable region, a second heavy chain variable region, and an Fc region, wherein the first heavy chain variable region is connected to the Fc region by a first peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids, and the second heavy chain variable region is connected to the Fc region by a second peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids.

[0007] Y et another aspect of the disclosure provides a heavy-chain antibody comprising a first heavy chain variable (VH) region that binds to IL2RB, a second heavy chain variable region that binds to IL2RG, and an Fc region that comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, and a cysteine at position 302, all according to EU numbering.

[0008] Still another aspect of the disclosure provides a heavy-chain antibody comprising a first heavy chain variable (VH) region that binds to IL2RB, a second heavy chain variable region that binds to IL2RG, and an Fc region, wherein the first heavy chain variable region is connected to the Fc region by a first peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids, and the second heavy chain variable region is connected to the Fc region by a second peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids.

[0009] A further aspect of the disclosure provides a heavy-chain antibody comprising a first heavy chain that binds to IL2RB comprising the amino acid sequence of SEQ ID NO: 38 and a second heavy chain that binds to IL2RG comprising the amino acid sequence of SEQ ID NO: 39.

[0010] Another aspect of the disclosure provides a pharmaceutical composition comprising a heavy-chain antibody disclosed herein and a pharmaceutically acceptable excipient.

[0011] Yet another aspect of the disclosure provides a method of treating cancer in a subject in need of such treatment, the method comprising administering to the subject a therapeutically effective amount of a heavy-chain antibody disclosed herein or a pharmaceutical composition comprising a heavy-chain antibody disclosed herein. In some embodiments, the method further comprises administering to the subject a T-cell redirecting therapy (e.g., a bispecific T-cell engaging molecule, such as, e.g., tarlatamab).

[0012] Still another aspect of the disclosure provides a heavy-chain antibody disclosed herein for use as a medicament. Another aspect of the disclosure provides a heavy-chain antibody disclosed herein, or a pharmaceutical composition disclosed herein, for use in the treatment of cancer, optionally in combination with a T-cell redirecting therapy (e.g., a bispecific T-cell engaging molecule, such as, e.g., tarlatamab).

[0013] Y et another aspect of the disclosure provides a use of a heavy-chain antibody disclosed herein for the manufacture of a medicament for the treatment of cancer.

[0014] Another aspect of the disclosure provides a method of treating a DLL3 -expressing cancer in a subject in need of such treatment, the method comprising administering to the subject a therapeutically effective amount of an IL-2-based therapy (e.g., an IL-2 -based therapy that preferentially binds to the heterodimeric receptor composed only of IL-2RJ3 and IL-2Ry over the trimeric IL-2RaPy form of the IL-2 receptor) and a T-cell redirecting therapy that binds to DLL3 (e.g., a bispecific T-cell engaging molecule that binds to DLL3, such as, e.g., tarlatamab). Still another aspect of the disclosure provides an IL-2 -based therapy (e.g., a heavy-chain antibody disclosedherein), or a pharmaceutical composition comprising the same, for use in the treatment of a DLL3- expressing cancer, in combination with a T-cell redirecting therapy that binds to DLL3 (e.g., a bispecific T-cell engaging molecule that binds to DLL3, such as, e.g., tarlatamab). Yet another aspect of the disclosure provides a use of an IL-2-based therapy (e.g., a heavy-chain antibody disclosed herein) for the manufacture of a medicament for the treatment of a DLL3 -expressing cancer, wherein the medicament is adapted for administration in combination with a T-cell redirecting therapy that binds to DLL3 (e.g., a bispecific T-cell engaging molecule that binds to DLL3, such as, e.g., tarlatamab).

[0015] Further aspects and advantages will be apparent to those of ordinary skill in the art from a review of the following detailed description. The description hereafter includes specific cases, embodiments, and examples with the understanding that the disclosure is illustrative and is not intended to limit the features of the present disclosure to the specific cases, embodiments, and examples described herein. Illustratively, some example embodiments of the present disclosure include, but are not limited to, the following embodiments E1-E216.El. A heavy-chain antibody comprising : a first heavy chain variable (VH) region that binds to IL2RB comprising:(1) (a) a VH complementarity determining region one (CDR1) comprising the amino acid sequence:G G S I S S S X1 W (SEQ ID NO: 26), wherein XI is D or N;(b) a VH CDR2 comprising the amino acid sequence:I X2 H S G S T (SEQ ID NO: 27), wherein X2 is D or S; and(c) a VH CDR3 comprising the amino acid sequence:X3 R G X4 W E L X5 D A F D I (SEQ ID NO: 28), wherein X3 is G or A; X4 is S or Q; and X5 is S or T; or(2) (a) a VH CDR1 comprising the amino acid sequence:G F T F S X1 Y G (SEQ ID NO: 29), wherein XI is S or T;(b) a VH CDR2 comprising the amino acid sequence:I S Y D G S N X2 (SEQ ID NO: 30), wherein X2 is K or R; and(c) a VH CDR3 comprising the amino acid sequence: A R D L D Y D X3 L T G D P V G G F D I (SEQ ID NO: 31), wherein X3 is V or I; a second heavy chain variable region that binds to IL2RG comprising:(1) (a) a VH CDR1 comprising the amino acid sequence:G F XI X2 X3 X4 Y Y (SEQ ID NO: 32), wherein XI is T or I; X2 is F or V; X3 is S, N, or G; and X4 is D or N;(b) a VH CDR2 comprising the amino acid sequence:I S X5 S G X6 X7 I (SEQ ID NO: 33), wherein X5 is S or N; X6 is D, S, G, or N; and X7 is T or I; and(c) a VH CDR3 comprising the amino acid sequence ARGDAVSITGDY (SEQ ID NO: 20); or(2) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 15, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 19, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 21; and an Fc region comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, and a cysteine at position 302, all according to EU numbering.E2. The heavy-chain antibody of El, wherein the Fc region comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34.E3. The heavy-chain antibody of El, wherein the Fc region comprises a first polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering.E4. The heavy-chain antibody of E3, wherein the Fc region further comprises a second polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.E5. The heavy-chain antibody of any one of E1-E4, wherein the Fc region comprises a first polypeptide chain comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering.E6. The heavy-chain antibody of any one of E3-E5, wherein the Fc region further comprises a second polypeptide chain comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.E7. The heavy-chain antibody of El, wherein the Fc region comprises: a first polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering; and a second polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.E8. The heavy-chain antibody of claim E7, wherein the first polypeptide chain comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, and the second polypeptide chain comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34.E9. The heavy-chain antibody of any one of E3-E8, wherein the first polypeptide chain comprises the amino acid sequence of SEQ ID NO: 35.E10. The heavy-chain antibody of any one of E4-E9, wherein the second polypeptide chain comprises the amino acid sequence of SEQ ID NO: 36.El l. The heavy-chain antibody of any one of E4-E 10, wherein the first polypeptide chain comprises the amino acid sequence of SEQ ID NO: 35, and the second polypeptide chain comprises the amino acid sequence of SEQ ID NO: 36.E12. The heavy-chain antibody of any one of El-El 1, wherein the first heavy chain variable region is connected to the Fc region by a first peptide linker.E13. The heavy-chain antibody of any one of El -El 2, wherein the second heavy chain variable region is connected to the Fc region by a second peptide linker.E14. The heavy-chain antibody of any one of El -El 3, wherein the first heavy chain variable region is connected to the Fc region by a first peptide linker, and the second heavy chain variable region is connected to the Fc region by a second peptide linker.E15. The heavy-chain antibody of any one of E7-E14, wherein: the first heavy chain variable region is connected to the first polypeptide chain of the Fc region by a first peptide linker; and the second heavy chain variable region is connected to the second polypeptide chain of the Fc region by a second peptide linker.E16. The heavy-chain antibody of any one of E7-E14, wherein: the first heavy chain variable region is connected to the second polypeptide chain of the Fc region by a first peptide linker; and the second heavy chain variable region is connected to the first polypeptide chain of the Fc region by a second peptide linker.El 7. The heavy-chain antibody of any one of E12-E16, wherein the first peptide linker is a poly-Gly linker.El 8. The heavy-chain antibody of any one of E13-E17, wherein the second peptide linker is a poly-Gly linker.El 9. The heavy-chain antibody of any one of E13-E18, wherein the first peptide linker and the second peptide linker are independently poly-Gly linkers.E20. The heavy-chain antibody of any one of E12-E19, wherein the first peptide linker comprises the amino acid sequence of GGGG (SEQ ID NO: 37).E21. The heavy-chain antibody of any one of E13-E20, wherein the second peptide linker comprises the amino acid sequence of GGGG (SEQ ID NO: 37).E22. The heavy-chain antibody of any one of E13-E21, wherein the first peptide linker and the second peptide linker both comprise the amino acid sequence of GGGG (SEQ ID NO: 37).E23. A heavy-chain antibody comprising: a first heavy chain variable (VH) region that binds to IL2RB comprising:(1) (a) a VH complementarity determining region one (CDR1) comprising the amino acid sequence:G G S I S S S X1 W (SEQ ID NO: 26), wherein XI is D or N;(b) a VH CDR2 comprising the amino acid sequence:I X2 H S G S T (SEQ ID NO: 27), wherein X2 is D or S; and(c) a VH CDR3 comprising the amino acid sequence:X3 R G X4 W E L X5 D A F D I (SEQ ID NO: 28), wherein X3 is G or A; X4 is S or Q; and X5 is S or T; or(2) (a) a VH CDR1 comprising the amino acid sequence:G F T F S X1 Y G (SEQ ID NO: 29), wherein XI is S or T;(b) a VH CDR2 comprising the amino acid sequence:I S Y D G S N X2 (SEQ ID NO: 30), wherein X2 is K or R; and(c) a VH CDR3 comprising the amino acid sequence:A R D L D Y D X3 L T G D P V G G F D I (SEQ ID NO: 31), wherein X3 is V or I; a second heavy chain variable region that binds to IL2RG comprising:(1) (a) a VH CDR1 comprising the amino acid sequence:G F XI X2 X3 X4 Y Y (SEQ ID NO: 32), wherein XI is T or I; X2 is F or V; X3 is S, N, or G; and X4 is D or N;(b) a VH CDR2 comprising the amino acid sequence:I S X5 S G X6 X7 I (SEQ ID NO: 33), wherein X5 is S or N; X6 is D, S, G, or N; and X7 is T or I; and(c) a VH CDR3 comprising the amino acid sequence ARGDAVSITGDY (SEQ ID NO: 20); or(2) a VH CDR1 comprising the amino acid sequence of SEQ ID NO: 15, a VH CDR2 comprising the amino acid sequence of SEQ ID NO: 19, and a VH CDR3 comprising the amino acid sequence of SEQ ID NO: 21; and an Fc region, wherein the first heavy chain variable region is connected to the Fc region by a first peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5,6, 7, 8, 9, 10) amino acids, and the second heavy chain variable region is connected to the Fc region by a second peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids.E24. The heavy-chain antibody of E23, wherein the first peptide linker comprises between 4 and 10 amino acids.E25. The heavy-chain antibody of E23 or E24, wherein the second peptide linker comprises between 4 and 10 amino acids.E26. The heavy-chain antibody of any one of E23-E25, wherein the first peptide linker comprises between 4 and 10 amino acids, and the second peptide linker comprises between 4 and 10 amino acids.E27. The heavy-chain antibody of any one of E23-E26, wherein the first peptide linker comprises 4 amino acids.E28. The heavy-chain antibody of any one of E23-E27, wherein the second peptide linker comprises 4 amino acids.E29. The heavy-chain antibody of any one of E23-E28, wherein the first peptide linker comprises 4 amino acids, and the second peptide linker comprises 4 amino acids.E30. The heavy-chain antibody of any one of E23-E29, wherein the first peptide linker is a flexible linker.E31. The heavy-chain antibody of any one of E23-E30, wherein the second peptide linker is a flexible linker.E32. The heavy-chain antibody of any one of E23-E31, wherein the first peptide linker and the second peptide linker are both flexible linkers.E33. The heavy-chain antibody of any one of E23-E32, wherein the first peptide linker and / or the second peptide linker comprises the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)m, wherein m is anumber in the range of 1 to 5 (SEQ ID NO: 40), or the amino acid sequence of (Gly-Gly-Gly-Gly- Gln)n, wherein n is a number in the range of 1 to 5 (SEQ ID NO: 82).E34. The heavy-chain antibody of any one of E23-E33, wherein the first peptide linker and the second peptide linker independently comprise the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)m, wherein m is a number in the range of 1 to 5 (SEQ ID NO: 40), or the amino acid sequence of (Gly- Gly-Gly-Gly-Gln)n, wherein n is a number in the range of 1 to 5 (SEQ ID NO: 82).E35. The heavy-chain antibody of any one of E23-E33, wherein the first peptide linker and / or the second peptide linker comprises the amino acid sequence of (Gly)p, wherein p is a number in the range of 4 to 10 (SEQ ID NO: 41).E36. The heavy-chain antibody of any one of E23-E32, wherein the first peptide linker and the second peptide linker independently comprise the amino acid sequence of (Gly)p, wherein p is a number in the range of 4 to 10 (SEQ ID NO: 41).E37. The heavy-chain antibody of any one of E23-E32, wherein the first peptide linker comprises the amino acid sequence of GGGG (SEQ ID NO: 37).E38. The heavy-chain antibody of any one of E23-E32, wherein the second peptide linker comprises the amino acid sequence of GGGG (SEQ ID NO: 37).E39. The heavy-chain antibody of any one of E23-E32, wherein the first peptide linker and the second peptide linker both comprise the amino acid sequence of GGGG (SEQ ID NO: 37).E40. The heavy-chain antibody of any one of E23-E32, wherein the first peptide linker only comprises glycine, serine, glutamine, and threonine amino acids.E41. The heavy-chain antibody of any one of E23-E32, wherein the second peptide linker only comprises glycine, serine, glutamine, and threonine amino acids.E42. The heavy-chain antibody of any one of E23-E32, wherein the first peptide linker and the second peptide linker both only comprise glycine, serine, glutamine, and threonine amino acids.E43. The heavy-chain antibody of any one of E23-E42, wherein the Fc region comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, whereinthe amino acid sequence comprises a glycine at position 297, a cysteine at position 292, and a cysteine at position 302, all according to EU numbering.E44. The heavy-chain antibody of any one of E23-E43, wherein the Fc region comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34.E45. The heavy-chain antibody of any one of E23-E42, wherein the Fc region comprises: a first polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering; and a second polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.E46. The heavy-chain antibody of E45, wherein the first polypeptide chain comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, and the second polypeptide chain comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34.E47. The heavy-chain antibody of E45 or E46, wherein the first polypeptide chain comprises the amino acid sequence of SEQ ID NO: 35, and the second polypeptide chain comprises the amino acid sequence of SEQ ID NO: 36.E48. The heavy-chain antibody of E23, wherein: the Fc region comprises a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 35 and a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 36; and the first peptide linker and the second peptide linker are independently poly-Gly linkers.E49. The heavy-chain antibody of E23 or E48, wherein: the Fc region comprises a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 35 and a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 36; andthe first peptide linker and the second peptide linker both comprise the amino acid sequence of GGGG (SEQ ID NO: 37).E50. The heavy-chain antibody of any one of E1-E49, wherein the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 26, SEQ ID NO: 27, and SEQ ID NO: 28, respectively.E51. The heavy-chain antibody of any one of E 1 -E49, wherein the VH CDR1 , the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 29, SEQ ID NO: 30, and SEQ ID NO: 31, respectively.E52. The heavy-chain antibody of any one of E1-E51, wherein the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 32, SEQ ID NO: 33, and SEQ ID NO: 20, respectively.E53. The heavy-chain antibody of any one of E1-E51, wherein the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 19, and SEQ ID NO: 21, respectively.E54. The heavy-chain antibody of any one of E1-E49, wherein: the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 26, SEQ ID NO: 27, and SEQ ID NO: 28, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 32, SEQ ID NO: 33, and SEQ ID NO: 20, respectively.E55. The heavy-chain antibody of any one of E1-E49, wherein: the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 26, SEQ ID NO: 27, and SEQ ID NO: 28, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 19, and SEQ ID NO: 21, respectively.E56. The heavy-chain antibody of any one of E1-E49, wherein: the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 29, SEQ ID NO: 30, and SEQ ID NO: 31, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 32, SEQ ID NO: 33, and SEQ ID NO: 20, respectively.E57. The heavy-chain antibody of any one of E1-E49, wherein: the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 29, SEQ ID NO: 30, and SEQ ID NO: 31, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 19, and SEQ ID NO: 21, respectively.E58. The heavy-chain antibody of E 1 -E49, wherein:(a) the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 1 or SEQ ID NO: 2; SEQ ID NO: 4 or SEQ ID NO: 5; and SEQ ID NO: 7, SEQ ID NO: 8, or SEQ ID NO: 9, respectively; or(b) the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 3, SEQ ID NO: 6, and SEQ ID NO: 10, respectively.E59. The heavy-chain antibody of E58, wherein the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 1 or SEQ ID NO: 2; SEQ ID NO: 4 or SEQ ID NO: 5; and SEQ ID NO: 7, SEQ ID NO: 8, or SEQ ID NO: 9, respectively.E60. The heavy-chain antibody of E58, wherein the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 3, SEQ ID NO: 6, and SEQ ID NO: 10, respectively.E61. The heavy-chain antibody of any one of E1-E49, wherein the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of:(a) SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 7, respectively; or(b) SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 8, respectively; or(c) SEQ ID NO: 2, SEQ ID NO: 5, and SEQ ID NO: 9, respectively; or(d) SEQ ID NO: 3, SEQ ID NO: 6, and SEQ ID NO: 10, respectively.E62. The heavy-chain antibody of E61, wherein the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of:(a) SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 7, respectively; or(b) SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 8, respectively; or(c) SEQ ID NO: 2, SEQ ID NO: 5, and SEQ ID NO: 9, respectively.E63. The heavy-chain antibody of any one of E1-E49, wherein the first VH region comprises an amino acid sequence that is at least 95% identical to any one of SEQ ID NOs: 11-14.E64. The heavy-chain antibody of E63, wherein the first VH region comprises an amino acid sequence that is at least 95% identical to any one of SEQ ID NOs: 11-13.E65. The heavy-chain antibody of any one of E1-E49, wherein the first VH region comprises an amino acid sequence selected from SEQ ID NOs: 11-14.E66. The heavy-chain antibody of E65, wherein the first VH region comprises an amino acid sequence selected from SEQ ID NOs: 11-13.E67. The heavy-chain antibody of any one of E1-E66, wherein:(a) the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15 or SEQ ID NO: 16; SEQ ID NO: 17 or SEQ ID NO: 18; and SEQ ID NO: 20, respectively; or(b) the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 19, and SEQ ID NO: 21, respectively.E68. The heavy-chain antibody of any one of E1-E67, wherein the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15 or SEQ ID NO: 16; SEQ ID NO: 17 or SEQ ID NO: 18; and SEQ ID NO: 20, respectively.E69. The heavy-chain antibody of any one of E1-E67, wherein the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 19, and SEQ ID NO: 21, respectively.E70. The heavy-chain antibody of any one of E1-E66, wherein the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of:(a) SEQ ID NO: 15, SEQ ID NO: 17, and SEQ ID NO: 20, respectively; or(b) SEQ ID NO: 15, SEQ ID NO: 18, and SEQ ID NO: 20, respectively; or(c) SEQ ID NO: 16, SEQ ID NO: 18, and SEQ ID NO: 20, respectively; or(d) SEQ ID NO: 15, SEQ ID NO: 19, and SEQ ID NO: 21, respectively.E71. The heavy-chain antibody of E70, wherein the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of:(a) SEQ ID NO: 15, SEQ ID NO: 17, and SEQ ID NO: 20, respectively; or(b) SEQ ID NO: 15, SEQ ID NO: 18, and SEQ ID NO: 20, respectively; or(c) SEQ ID NO: 16, SEQ ID NO: 18, and SEQ ID NO: 20, respectively.E72. The heavy-chain antibody of any one of E1-E66, wherein the second VH region comprises an amino acid sequence that is at least 95% identical to any one of SEQ ID NOs: 22-25.E73. The heavy-chain antibody of E72, wherein the second VH region comprises an amino acid sequence that is at least 95% identical to any one of SEQ ID NOs: 22-24.E74. The heavy-chain antibody of any one of E1-E66, wherein the second VH region comprises an amino acid sequence selected from SEQ ID NOs: 22-25.E75. The heavy-chain antibody of E74, wherein the second VH region comprises an amino acid sequence selected from SEQ ID NOs: 22-24.E76. The heavy-chain antibody of any one of E1-E49, wherein: the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 7, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 17, and SEQ ID NO: 20, respectively.E77. The heavy-chain antibody of any one of E1-E49 or E76, wherein the first VH region comprises an amino acid sequence that is at least 95% identical to SEQ ID NO: 11, and the second VH region comprises an amino acid sequence that is at least 95% identical to SEQ ID NO: 22.E78. The heavy-chain antibody of any one of E1-E49, E76, or E77, wherein the first VH region comprises the amino acid sequence of SEQ ID NO: 11, and the second VH region comprises the amino acid sequence of SEQ ID NO: 22.E79. The heavy-chain antibody of any one of E1-E49, wherein: the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 8, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 18, and SEQ ID NO: 20, respectively.E80. The heavy-chain antibody of any one of E1-E49 or E79, wherein the first VH region comprises an amino acid sequence that is at least 95% identical to SEQ ID NO: 12, and the second VH region comprises an amino acid sequence that is at least 95% identical to SEQ ID NO: 23.E81. The heavy-chain antibody of any one of E1-E49, E79, or E80, wherein the first VH region comprises the amino acid sequence of SEQ ID NO: 12, and the second VH region comprises the amino acid sequence of SEQ ID NO: 23.E82. The heavy-chain antibody of any one of E1-E49, wherein: the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 2, SEQ ID NO: 5, and SEQ ID NO: 9, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 18, and SEQ ID NO: 20, respectively.E83. The heavy-chain antibody of any one of E1-E49 or E82, wherein the first VH region comprises an amino acid sequence that is at least 95% identical to SEQ ID NO: 13, and the second VH region comprises an amino acid sequence that is at least 95% identical to SEQ ID NO: 23.E84. The heavy-chain antibody of any one of E1-E49, E82, or E83, wherein the first VH region comprises the amino acid sequence of SEQ ID NO: 13, and the second VH region comprises the amino acid sequence of SEQ ID NO: 23.E85. The heavy-chain antibody of any one of E1-E49, wherein: the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 8, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 16, SEQ ID NO: 18, and SEQ ID NO: 20, respectively.E86. The heavy-chain antibody of any one of E1-E49 or E85, wherein the first VH region comprises an amino acid sequence that is at least 95% identical to SEQ ID NO: 12, and the second VH region comprises an amino acid sequence that is at least 95% identical to SEQ ID NO: 24.E87. The heavy-chain antibody of any one of E1-E49, E85, or E86, wherein the first VH region comprises the amino acid sequence of SEQ ID NO: 12, and the second VH region comprises the amino acid sequence of SEQ ID NO: 24.E88. The heavy-chain antibody of any one of E1-E49, wherein: the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 8, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 19, and SEQ ID NO: 21, respectively.E89. The heavy-chain antibody of any one of E1-E49 or E88, wherein the first VH region comprises an amino acid sequence that is at least 95% identical to SEQ ID NO: 12, and the second VH region comprises an amino acid sequence that is at least 95% identical to SEQ ID NO: 25.E90. The heavy-chain antibody of any one of E1-E49, E88, or E89, wherein the first VH region comprises the amino acid sequence of SEQ ID NO: 12, and the second VH region comprises the amino acid sequence of SEQ ID NO: 25.E91. A heavy-chain antibody comprising : a first heavy chain variable (VH) region that binds to IL2RB in which the full set of VH complementarity determining regions (CDRs) 1, 2, and 3 (combined) is at least 95% identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14; a second VH region that binds to IL2RG in which the full set of VH CDRs 1, 2, and 3 (combined) is at least 95% identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25; and an Fc region comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, and a cysteine at position 302, all according to EU numbering.E92. The heavy-chain antibody of E91, wherein the Fc region comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34.E93. The heavy-chain antibody of E91 , wherein the Fc region comprises a first polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering.E94. The heavy-chain antibody of E93, wherein the Fc region further comprises a second polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acidsequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.E95. The heavy-chain antibody of any one of E91-E94, wherein the Fc region comprises a first polypeptide chain comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering.E96. The heavy-chain antibody of any one of E93-E95, wherein the Fc region further comprises a second polypeptide chain comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.E97. The heavy-chain antibody of E91, wherein the Fc region comprises: a first polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering; and a second polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.E98. The heavy-chain antibody of claim E97, wherein the first polypeptide chain comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, and the second polypeptide chain comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34.E99. The heavy-chain antibody of any one of E93-E98, wherein the first polypeptide chain comprises the amino acid sequence of SEQ ID NO: 35.El 00. The heavy-chain antibody of any one of E94-E99, wherein the second polypeptide chain comprises the amino acid sequence of SEQ ID NO: 36.E 101. The heavy-chain antibody of any one of E94-E 100, wherein the first polypeptide chain comprises the amino acid sequence of SEQ ID NO: 35, and the second polypeptide chain comprises the amino acid sequence of SEQ ID NO: 36.E 102. The heavy-chain antibody of any one of E91 -E 101 , wherein the first VH region is connected to the Fc region by a first peptide linker.El 03. The heavy-chain antibody of any one of E91-E102, wherein the second VH region is connected to the Fc region by a second peptide linker.El 04. The heavy-chain antibody of any one of E91-E103, wherein the first VH region is connected to the Fc region by a first peptide linker, and the second VH region is connected to the Fc region by a second peptide linker.E 105. The heavy-chain antibody of any one of E97-E 104, wherein: the first VH region is connected to the first polypeptide chain of the Fc region by a first peptide linker; and the second VH region is connected to the second polypeptide chain of the Fc region by a second peptide linker.E106. The heavy-chain antibody of any one of E97-E104, wherein: the first VH region is connected to the second polypeptide chain of the Fc region by a first peptide linker; and the second VH region is connected to the first polypeptide chain of the Fc region by a second peptide linker.El 07. The heavy-chain antibody of any one of E102-E106, wherein the first peptide linker is a poly- Gly linker.E108. The heavy-chain antibody of any one of E103-E107, wherein the second peptide linker is a poly-Gly linker.E109. The heavy-chain antibody of any one of E103-E108, wherein the first peptide linker and the second peptide linker are independently poly-Gly linkers.E110. The heavy-chain antibody of any one of E102-E109, wherein the first peptide linker comprises the amino acid sequence of GGGG (SEQ ID NO: 37).E 111. The heavy-chain antibody of any one ofE103-E110, wherein the second peptide linker comprises the amino acid sequence of GGGG (SEQ ID NO: 37).El 12. The heavy-chain antibody of any one of E103-E111, wherein the first peptide linker and the second peptide linker both comprise the amino acid sequence of GGGG (SEQ ID NO: 37).E 113. A heavy-chain antibody comprising : a first heavy chain variable (VH) region that binds to IL2RB in which the full set of VH complementarity determining regions (CDRs) 1, 2, and 3 (combined) is at least 95% identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14; a second VH region that binds to IL2RG in which the full set of VH CDRs 1, 2, and 3 (combined) is at least 95% identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25; and an Fc region, wherein the first heavy chain variable region is connected to the Fc region by a first peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids, and the second heavy chain variable region is connected to the Fc region by a second peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids.El 14. The heavy-chain antibody of El 13, wherein the first peptide linker comprises between 4 and 10 amino acids.El 15. The heavy-chain antibody of El 13 or El 14, wherein the second peptide linker comprises between 4 and 10 amino acids.El 16. The heavy-chain antibody of any one ofE113-E115, wherein the first peptide linker comprises between 4 and 10 amino acids, and the second peptide linker comprises between 4 and 10 amino acids.El 17. The heavy-chain antibody of any one of El 13 -El 16, wherein the first peptide linker comprises 4 amino acids.E 118. The heavy-chain antibody of any one ofE113-E117, wherein the second peptide linker comprises 4 amino acids.El 19. The heavy-chain antibody of any one of El 13-E118, wherein the first peptide linker comprises 4 amino acids, and the second peptide linker comprises 4 amino acids.El 20. The heavy-chain antibody of any one of El 13 -El 19, wherein the first peptide linker is a flexible linker.E121. The heavy-chain antibody of any one of El 13 -El 20, wherein the second peptide linker is a flexible linker.El 22. The heavy-chain antibody of any one of El 13 -E 121, wherein the first peptide linker and the second peptide linker are both flexible linkers.El 23. The heavy-chain antibody of any one of El 13 -El 22, wherein the first peptide linker and / or the second peptide linker comprises the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)m, wherein m is a number in the range of 1 to 5 (SEQ ID NO: 40), or the amino acid sequence of (Gly-Gly-Gly-Gly- Gln)n, wherein n is a number in the range of 1 to 5 (SEQ ID NO: 82).El 24. The heavy-chain antibody of any one of El 13 -El 23, wherein the first peptide linker and the second peptide linker independently comprise the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)m, wherein m is a number in the range of 1 to 5 (SEQ ID NO: 40), or the amino acid sequence of (Gly- Gly-Gly-Gly-Gln)n, wherein n is a number in the range of 1 to 5 (SEQ ID NO: 82).El 25. The heavy-chain antibody of any one of El 13 -El 23, wherein the first peptide linker and / or the second peptide linker comprises the amino acid sequence of (Gly)p, wherein p is a number in the range of 4 to 10 (SEQ ID NO: 41).El 26. The heavy-chain antibody of any one of El 13 -El 22, wherein the first peptide linker and the second peptide linker independently comprise the amino acid sequence of (Gly)p, wherein p is a number in the range of 4 to 10 (SEQ ID NO: 41).El 27. The heavy-chain antibody of any one of El 13 -El 22, wherein the first peptide linker comprises the amino acid sequence of GGGG (SEQ ID NO: 37).E128. The heavy-chain antibody of any one of El 13-E122, wherein the second peptide linker comprises the amino acid sequence of GGGG (SEQ ID NO: 37).El 29. The heavy-chain antibody of any one of El 13 -El 22, wherein the first peptide linker and the second peptide linker both comprise the amino acid sequence of GGGG (SEQ ID NO: 37).E130. The heavy-chain antibody of any one of El 13-E122, wherein the first peptide linker only comprises glycine, serine, glutamine, and threonine amino acids.E131. The heavy-chain antibody of any one of El 13-E122, wherein the second peptide linker only comprises glycine, serine, glutamine, and threonine amino acids.E132. The heavy-chain antibody of any one of El 13-E122, wherein the first peptide linker and the second peptide linker both only comprise glycine, serine, glutamine, and threonine amino acids.E133. The heavy-chain antibody of any one of El 13-E132, wherein the Fc region comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, and a cysteine at position 302, all according to EU numbering.E134. The heavy-chain antibody of any one of El 13-E133, wherein the Fc region comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34.E135. The heavy-chain antibody of any one of El 13-E132, wherein the Fc region comprises: a first polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering; and a second polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.E136. The heavy-chain antibody of E135, wherein the first polypeptide chain comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, and thesecond polypeptide chain comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34.E 137. The heavy-chain antibody of E135 or E136, wherein the first polypeptide chain comprises the amino acid sequence of SEQ ID NO: 35, and the second polypeptide chain comprises the amino acid sequence of SEQ ID NO: 36.E 138. The heavy-chain antibody of E 113, wherein: the Fc region comprises a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 35 and a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 36; and the first peptide linker and the second peptide linker are independently poly-Gly linkers.E139. The heavy-chain antibody of El 13 or E138, wherein: the Fc region comprises a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 35 and a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 36; and the first peptide linker and the second peptide linker both comprise the amino acid sequence of GGGG (SEQ ID NO: 37).El 40. The heavy-chain antibody of any one of E91-E139, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT.E141. The heavy-chain antibody of any one of E91-E140, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14, wherein the VH CDRs 1, 2, and 3 are defined by Kabat.El 42. The heavy-chain antibody of any one of E91-E140, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14, wherein the VH CDRs 1, 2, and 3 are defined by Chothia.El 43. The heavy-chain antibody of any one of E91-E140, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.El 44. The heavy-chain antibody of any one of E91-E143, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT.El 45. The heavy-chain antibody of any one of E91-E144, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25, wherein the VH CDRs 1, 2, and 3 are defined by Kabat.El 46. The heavy-chain antibody of any one of E91-E144, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25, wherein the VH CDRs 1, 2, and 3 are defined by Chothia.El 47. The heavy-chain antibody of any one of E91-E144, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.E148. The heavy-chain antibody of any one of E91-E139, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14.El 49. The heavy-chain antibody of any one of E91-E139, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT.El 50. The heavy-chain antibody of any one of E91-E139, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14, wherein the VH CDRs 1, 2, and 3 are defined by Kabat.E151. The heavy-chain antibody of any one of E91-E139, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14, wherein the VH CDRs 1, 2, and 3 are defined by Chothia.E152. The heavy-chain antibody of any one of E91-E139, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.E153. The heavy-chain antibody of any one of E91-E139 or E148-E152, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25.E154. The heavy-chain antibody of any one of E91-E139 or E148-E152, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT.E155. The heavy-chain antibody of any one of E91-E139 or E148-E152, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25, wherein the VH CDRs 1, 2, and 3 are defined by Kabat.E156. The heavy-chain antibody of any one of E91-E139 or E148-E152, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25, wherein the VH CDRs 1, 2, and 3 are defined by Chothia.E157. The heavy-chain antibody of any one of E91-E139 or E148-E152, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.E158. The heavy-chain antibody of any one of E91-E139, wherein: the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22.E159. The heavy-chain antibody of any one of E91-E139, wherein: the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22.E160. The heavy-chain antibody of any one of E91-E139, wherein: the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23.E161. The heavy-chain antibody of any one of E91-E139, wherein: the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23.E162. The heavy-chain antibody of any one of E91-E139, wherein: the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23.E163. The heavy-chain antibody of any one of E91-E139, wherein: the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23.E164. The heavy-chain antibody of any one of E91-E139, wherein: the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 14; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22.E165. The heavy-chain antibody of any one of E91-E139, wherein: the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 14; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22.E166. The heavy-chain antibody of any one of E91-E139, wherein: the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24.E167. The heavy-chain antibody of any one of E91-E139, wherein: the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24.E168. The heavy-chain antibody of any one of E91-E139, wherein: the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 95% identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25.E169. The heavy-chain antibody of any one of E91-E139, wherein: the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25.E 170. A heavy-chain antibody comprising : a first heavy chain that binds to IL2RB comprising the amino acid sequence of SEQ IDNO: 38; and a second heavy chain that binds to IL2RG comprising the amino acid sequence of SEQ IDNO: 39.E171. The heavy-chain antibody of E1-E170, wherein: the heavy-chain antibody has an affinity for IL2R with a Kd in the range of 1011M to 10'6M; and / or the heavy-chain antibody has an affinity for IL2RP with a Kd in the range of 10'8M to 2.5 x 10'7M; and / orthe heavy-chain antibody has an affinity for IL2Ry with a Kd in the range of 10'9M to 2.5 xIO'8M.E172. The heavy-chain antibody of any one of E1-E171, wherein the heavy-chain antibody is an IL-2RPy agonist.E173. A pharmaceutical composition comprising: a heavy-chain antibody of any one of El -El 72; and a pharmaceutically acceptable excipient.E174. The pharmaceutical composition of E173, wherein the pharmaceutical composition is adapted for intravenous or subcutaneous administration.El 75. A method of treating cancer in a subject in need thereof, comprising administering to the subject a heavy-chain antibody of any one of El -El 72 or a pharmaceutical composition of El 73 or E174.El 76. A method of treating cancer in a subject in need thereof, comprising administering to the subject a heavy-chain antibody of any one of El -El 72 or a pharmaceutical composition of El 73 or El 74 in combination with a T-cell redirecting therapy.E177. A method of enhancing an anti-cancer effect associated with administration of a T-cell redirecting therapy in a subject diagnosed with cancer, comprising administering to the subject a heavy-chain antibody of any one of E1-E172 or a pharmaceutical composition of E173 or E174 in combination with the T-cell redirecting therapy.E 178. The method of E176 or E177, further comprising administering a premedication to the subj ect prior to the administration of a first dose of the heavy-chain only antibody or a first dose of the T-cell redirecting therapy.E179. The method of E178, wherein the premedication is selected from antihistamines, glucocorticoids, IL-6 receptor antagonists, and tumor necrosis factor alpha (TNF-a) antagonists.E180. The method of any one of E176-E179, wherein the T-cell redirecting therapy is a bispecific T-cell engaging molecule.E 181. The method of El 80, wherein the bispecific T-cell engaging molecule comprises a first domain that binds to a target cancer cell antigen and a second domain that binds to human CD3.El 82. The method of El 81, wherein the target cancer cell antigen is selected from EpCAM, CEA, CD19, CD33, CD70, EGFRvIII, FLT3, GPRC5D, DLL3, BCMA, PSMA, STEAP1, STEAP2, MUC16, MUC17, and CLDN18.2.E 183. The method of E 181 or E 182, wherein the target cancer cell antigen is DLL3.E184. The method of any one of E176-E183, wherein the bispecific T-cell engaging molecule further comprises a half-life extension domain.E 185. The method of E 184, wherein the half-life extension domain provides a half-life for the bispecific T-cell engaging molecule of at least 24 hours.E186. The method of E184 or E185, wherein the half-life extension domain is selected from immunoglobulin Fc domains, domains derived from serum albumin (e.g., human serum albumin), albumin-binding domains (e.g., comprising human albumin binding peptides or an antibody fragment that binds to serum albumin), peptides that bind to the neonatal Fc receptor (FcRn), and polyethylene glycol polymers.E187. The method of any one of E176-E184, wherein the T-cell redirecting therapy is tarlatamab.E188. The method of any one of E176-E186, wherein the bispecific T-cell engaging molecule is a three-chain antibody-like molecule, a heterodimeric IgG molecule (hetero-IgG), or a half-life extended (HLE) BiTE® molecule.E189. The method of any one of E176-E179, wherein the T-cell redirecting therapy is a chimeric antigen receptor (CAR)-expressing T-cell.E190. The method of E189, wherein the CAR-expressing T-cell comprises a first domain that binds to a target cancer cell antigen, a transmembrane domain, and an intracellular signaling domain.E191. The method of El 90, wherein the target cancer cell antigen is selected from EpCAM, CEA, CD19, CD33, CD70, EGFRvIII, FLT3, GPRC5D, DLL3, BCMA, PSMA, STEAP1, STEAP2, MUC16, MUC17, and CLDN18.2.El 92. The method of any one of E176-E191, wherein at least one dose of the heavy-chain only antibody is administered to the subject prior to a first dose of the T-cell redirecting therapy.E193. The method of any one of E176-E192, wherein the method comprises administering the heavy-chain only antibody in combination with the T-cell redirecting therapy in one or more treatment cycles.E194. The method of E193, wherein each of the one or more treatment cycles comprises a single dose of the heavy-chain only antibody and a single dose of the T-cell redirecting therapy.El 95. The method of El 93, wherein each of the one or more treatment cycles comprises multiple doses of the heavy-chain only antibody and a single dose of the T-cell redirecting therapy.E196. The method of E193, wherein each of the one or more treatment cycles comprises a single dose of the heavy-chain only antibody and multiple doses of the T-cell redirecting therapy.El 97. The method of El 93, wherein each of the one or more treatment cycles comprises multiple doses of the heavy-chain only antibody and multiple doses of the T-cell redirecting therapy.E198. The method of any one of E175-E182, E184-E186, or E188-E197, wherein the cancer is a hematologic cancer.E199. The method of E198, wherein the cancer is selected from acute myeloid leukemia, acute lymphocytic leukemia, chronic lymphocytic leukemia, chronic myeloid leukemia, multiple myeloma, diffuse large B-cell lymphoma, Burkitt lymphoma, and non-Hodgkin lymphoma.E200. The method of any one of El 75 -El 97, wherein the cancer is selected from prostate cancer, non-small cell lung cancer, small-cell lung cancer, renal cell carcinoma, hepatocellular carcinoma, bladder cancer, testicular cancer, colorectal cancer, esophageal cancer, glioblastoma, head and neck cancer, pancreatic cancer, breast cancer, gastric cancer, gastroesophageal junction cancer, bone cancer, ovarian cancer, endometrial cancer, and melanoma.E201. The method of E200, wherein the subject has at least one tumor with low immune infiltration (e.g., low T-cell infiltration) prior to the co-administration.E202. The method of E200 or E201, wherein the co-administration increases tumor T-cell infdtration.E203. The method of any one of E200-E202, wherein the co-administration is associated with at least one anti-tumor effect.E204. The method of E203, wherein the at least one anti -tumor effect is selected from a decrease in tumor volume, a decrease in the number of tumor cells, a decrease in tumor cell proliferation, and a decrease in tumor cell survival.E205. The method of any one of E176-E204, wherein the co-administration is associated with at least one anti -cancer effect.E206. The method of E205, wherein the at least one anti -cancer effect is selected from a decrease in the number of cancer cells, a decrease in the number of metastases, an increase in life expectancy, a decrease in cancer cell proliferation, a decrease in cancer cell survival, and an amelioration of various physiological symptoms associated with the cancerous condition.E207. The method of any one of E175-E206, wherein the heavy-chain only antibody is administered in a pharmaceutical composition adapted for intravenous or subcutaneous delivery.E208. The method of any one of E176-E207, wherein the T-cell redirecting therapy is administered in a pharmaceutical composition adapted for intravenous or subcutaneous delivery.E209. The method of E208, wherein the pharmaceutical composition comprises the bispecific T-cell engaging molecule, a buffer, a surfactant, and a stabilizing agent.E210. The method of E208 or E209, wherein the pharmaceutical composition comprises the bispecific T-cell engaging molecule, a glutamate buffer, polysorbate 20 or polysorbate 80, and sucrose, at a pH in the range of 4.0 to 4.4.E211. The method of any one of E176-E210, wherein the heavy-chain only antibody and the T-cell redirecting therapy are administered in separate pharmaceutical compositions.E212. The method of E211, wherein the separate pharmaceutical compositions may be lyophilized and reconstituted prior to administration to the subject.E213. The method of any one of E176-E212, wherein the heavy-chain only antibody and the T-cell redirecting therapy are administered concurrently.E214. The method of any one of E176-E212, wherein the heavy-chain only antibody and the T-cell redirecting therapy are administered sequentially.E215. The method of any one of E 175 -E214, wherein the subj ect was previously administered a first line therapy for the cancer.E216. The method of any one of El 75 -El 25, wherein the subject was previously administered a first line therapy and a second line therapy for the cancer.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIGs. 1A-1D show the binding of a heavy-chain antibody disclosed herein (“HCAbl”) to human CD4+T-cells (FIG. 1A), human CD4+CD25+CD12710T-regs (FIG. IB), human CD8+T-cells (FIG. 1C), and human CD3 CD56+NK cells (FIG. ID) relative to an IgGl isotype control antibody (“huIgGl”) as a function of concentration for each test article.

[0017] FIGs. 2A-2D show the binding of HCAbl to cyno CD4+T-cells (FIG. 2A), cyno CD4 CD25 CD12710T-regs (FIG. 2B), cyno CD8+T-cells (FIG. 2C), and cyno CD3 CD159a+NK cells (FIG. 2D) relative to an IgGl isotype control antibody as a function of concentration for each test article.

[0018] FIGs. 3A-3D depict STAT5 phosphorylation dose curves in human CD4+Foxp3 T-cells (FIG. 3A), human CD4+CD25+Foxp3+regulatory T-cells (FIG. 3B), human CD8+T-cells (FIG. 3C), and human CD3 CD56+NK cells (FIG. 3D) as a function of concentration for HCAbl and the control molecules (recombinant human IL-2 (“rhIL-2”) and IL-2 variant (“IL-2v”)).

[0019] FIGs. 4A-4D show the proliferation (Ki67 dose curves) of human CD4+Foxp3 T-cells (FIG. 4A), human CD4+CD25+Foxp3+regulatory T-cells (FIG. 4B), human CD8+T-cells (FIG. 4C), and human CD3 CD56+NK cells (FIG. 4D) as a function of concentration for HCAbl and the control molecules (rhIL-2 and IL-2v).

[0020] FIGs. 5A-5D show the proliferation (Ki67 dose curves) of cyno CD4+Foxp3 T-cells (FIG. 5A), cyno CD4+CD25+Foxp3+regulatory T-cells (FIG. 5B), cyno CD8+T-cells (FIG. 5C), and cyno CD3 CD159a+NK cells (FIG. 5D) as a function of concentration for HCAbl and the control molecules (rhIL-2 and IL-2v).

[0021] FIGs. 6A and 6B depict the results from a T-cell dependent cellular cytotoxicity (TDCC) assay (E:T = 5: 1, 72 hour assay time) using SHP-77 Luc cells to investigate cytotoxicity for tarlatamab (“DLL3-TCE”) alone and in combination with HCAbl, rhIL-2, or IL-2v at high (FIG. 6A) and medium (FIG. 6B) enabler concentrations.

[0022] FIGs. 7A-7K show measured cytokine concentrations (IFNy (FIG. 7A), IL-2 (FIG. 7B), IL- 6 (FIG. 7C), IL-10 (FIG. 7D), TNFa (FIG. 7E), Granzyme B (FIG. 7F), GM-CSF (FIG. 7G), IL-IRa (FIG. 7H), IL-5 (FIG. 71), MCP-1 (FIG. 7J), and MIP-ip (FIG. 7K)) from the TDCC assay (E:T = 5: 1, 72 hour assay time) using SHP-77 Luc cells at various tarlatamab (“DLL3-TCE”) concentrations, alone or in combination with high (300 nM, 30 nM, or 10 nM) concentrations of HCAbl, IL-2v, and rhIL-2, respectively.

[0023] FIGs. 8A-8K show measured cytokine concentrations (IFNy (FIG. 8A), IL-2 (FIG. 8B), IL- 6 (FIG. 8C), IL-10 (FIG. 8D), TNFa (FIG. 8E), Granzyme B (FIG. 8F), GM-CSF (FIG. 8G), IL-IRa (FIG. 8H), IL-5 (FIG. 81), MCP-1 (FIG. 8 J), and MIP-ip (FIG. 8K)) from the TDCC assay (E:T = 5: 1, 72 hour assay time) using SHP-77 Luc cells at various tarlatamab (“DLL3-TCE”) concentrations, alone or in combination with medium (30 nM, 2 nM, or 0.5 nM) concentrations of HCAbl, IL-2v, and rhIL-2, respectively.

[0024] FIG. 9 depicts the results from a serial T-cell engaging molecule exposure cytotoxicity assay (E:T = 2: 1) using NUGC4-CD58 KO cells to investigate exposure-mediated T-cell dysfunction for a T-cell engaging molecule that binds to human EpCAM and CD3 (“EpCAM-TCE”), alone and in combination with HCAbl, IL-2v, or a wild-type human IL-2 molecule conjugated to the same Fc region used in HCAbl (“wtIL2-Fc”).

[0025] FIGs. 10A-10D show measured cytokine concentrations (IL-5 (FIG. 10A), IL-6 (FIG. 10B), IL-10 (FIG. 10C), and TNFa (FIG. 10D)) from the serial T-cell engaging molecule exposure cytotoxicity assay (E:T = 2: 1) using NUGC4-CD58 KO cells to investigate exposure-mediated T-cell dysfunction for EpCAM-TCE alone and in combination with HCAbl, IL-2v, or wtIL2-Fc.

[0026] FIG. 11 shows concentration-dependent viscosity data, including exponential fit curves, for HCAbl and HCAb2 in a 10 mM acetate, 9% sucrose, 0.01% PS80, pH 5.2 formulation buffer at 5 °C and 25 °C.

[0027] FIG. 12 depicts the time -dependent percentage of higher-order aggregates present in 5 mg / mL formulations of HCAbl and HCAb2 over 4 weeks at 40 °C.

[0028] FIG. 13 is a graph showing tumor volume as a function of time between 11 and 32 days post-tumor implantation for mice in an in vivo combination study assessing HCAbl and tarlatamab (“DLL3-TCE”).

[0029] FIG. 14 is a graph showing relative body weight (%) as a function of time between 11 and 32 days post-tumor implantation for mice in an in vivo combination study assessing HCAbl and tarlatamab (“DLL3-TCE”).

[0030] FIG. 15 is a schematic depicting a non-limiting example structure for a heavy-chain antibody having activity as an agonist of the dimeric interleukin-2 receptor as described herein.

[0031] FIG. 16 provides non-human primate (NHP) pharmacokinetic (PK) data in graphical format. NHP (n=3 per group per timepoint) were administered 0.03, 0.1, or 0.3 mg / kg ofHCAbl by IV injection on Day 0 and Day 14. Serum was collected over 4 weeks and assessed by an electrochemiluminescence method using anti-idiotypic monoclonal antibodies.

[0032] FIGs. 17A-17D are graphs showing Harvest Titer (FIG. 17A), % SEC Main Peak(FIG. 17B), % HIC Main Peak (FIG. 17C), and % Capillary Electrophoresis non-reduced Main Peak (FIG. 17D) for eight example heavy chain antibodies (HCAbl, HCAb, HCAb3, HCAb4, HCAb5, HCAb6, HCAb7, and HCAb8).

[0033] FIG. 18 provides an example size exclusion chromatogram for HCAb2 at a concentration of 10 mg / mL in a 10 mM acetate, 9% sucrose, pH 5.2 formulation buffer after one week at 40 °C.

[0034] FIG. 19 depicts the time -dependent percentage of higher-order aggregates present in 10 mg / mL formulations ofHCAbl, HCAb2, HCAb3, HCAb4, HCAb5, HCAb6, HCAb7, and HCAb8 in 10 mM sodium acetate, 9% sucrose, pH 5.2 formulation buffer over the course of one week at 40 °C.DETAILED DESCRIPTION

[0035] Disclosed herein are heavy-chain antibodies having activity as agonists of the dimeric interleukin-2 receptor, pharmaceutical compositions comprising the heavy-chain antibodies, and uses and methods of treating disorders, such as cancer, with the heavy-chain antibodies and pharmaceutical compositions described herein.DEFINITIONS

[0036] The following definitions are provided to assist in understanding the scope of this disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0037] Other than in the Examples, or where otherwise indicated, all numbers expressing quantities (e.g., of components or reaction conditions) used herein should be understood as modified in all instances by the term “about.” As used herein, “about,” when used in connection with a measurable numerical variable, refers to the indicated value of the variable and to all values of the variable thatare within the experimental error of the indicated value (e.g., within the 95% confidence interval for the mean) or ± 10% of the indicated value, whichever is greater.

[0038] Where a range of values is provided, it should be understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the disclosure. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges also encompassed within the disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure.

[0039] As used herein, the terms “a” and “an” mean “one or more” unless specifically indicated otherwise. Additionally, “one or more” and “at least one” are used interchangeably herein. Furthermore, unless otherwise required by context, singular terms include pluralities and plural terms include the singular.

[0040] As used herein, the term “polypeptide” refers to a polymer of amino acid residues. Polypeptides comprising between two and fifty amino acids may also be referred to as “peptides” herein. “Polypeptide” further encompasses an amino acid polymer in which one or more amino acid residues is an analog or mimetic of a corresponding naturally occurring amino acid, as well as to naturally occurring amino acid polymers. The term can also encompass an amino acid polymer that have been modified, e.g., by the addition of carbohydrate residues to form glycoproteins, or phosphorylated. Polypeptides can be produced by a naturally-occurring and non-recombinant cell, or polypeptides can be produced by a genetically-engineered or recombinant cell, and comprise molecules having the amino acid sequence of the native protein, or molecules having deletions from, additions to, and / or substitutions of one or more amino acids of the native sequence. The terms “polypeptide” and “protein” are used interchangeably herein.

[0041] As used herein, a “derivative” of a polypeptide is a polypeptide (e.g., an antigen binding protein such as an antibody) that has been chemically modified in some manner distinct from insertion, deletion, or substitution variants, such as, e.g., via conjugation to another chemical moiety.

[0042] As used herein, the term “linker moiety” or “linker” refers to a biologically acceptable peptidyl or non-peptidyl organic group that is covalently bound to a first molecule (e.g., a first polypeptide) and covalently joins or conjugates the molecule to a second molecule (e.g., a second polypeptide). Where the linker moiety consists of a polypeptide or a polypeptide derivative (e.g., a polypeptide that has been chemically modified at one or both of the N-terminus and C-terminus to incorporate a functional group that permits conjugation to the first or second molecule), it may be referred to as a “polypeptide linker” herein. Where the peptidyl linker moiety comprises between two and fifty amino acids, it may also be referred to as a “peptide linker” herein. Additionally, as usedherein, a “linker,” such as a “peptide linker,” connected to an Fc region may be connected to a hinge region of the Fc region, wherein the hinge region is a naturally occurring / wild-type hinge region or a hinge region containing one or more modifications relative to a wild-type hinge region. In some embodiments, the linker is connected to a naturally occurring / wild-type hinge region. In alternative embodiments, a “linker,” such as a “peptide linker,” connected to an Fc region may be directly connected to a CH2 domain of the Fc region.

[0043] As used herein, the term “antibody” generally refers to a tetrameric immunoglobulin protein comprising two light chain polypeptides (such as, e.g., light chain polypeptides that are about 25 kDa each) and two heavy chain polypeptides (such as, e.g., heavy chain polypeptides that are about 50-70 kDa each). The term “light chain,” as used with respect to an antibody or a fragment thereof, includes a full-length light chain and fragments thereof having sufficient variable region sequence to confer binding specificity. A full-length light chain refers to a polypeptide comprising, from amino terminus to carboxyl terminus, a single immunoglobulin light chain variable region (VL) and a single immunoglobulin light chain constant domain (CL). The immunoglobulin light chain constant domain (CL) can be a human kappa (K) or human lambda (X) constant domain. The term “heavy chain,” as used with respect to an antibody or a fragment thereof, includes a full- length heavy chain and fragments thereof having sufficient variable region sequence to confer binding specificity. A full-length heavy chain refers to a polypeptide comprising, from amino terminus to carboxyl terminus, a single immunoglobulin heavy chain variable region (VH), an immunoglobulin heavy chain constant domain 1 (CHI), an immunoglobulin hinge region, an immunoglobulin heavy chain constant domain 2 (CH2), an immunoglobulin heavy chain constant domain 3 (CH3), and optionally an immunoglobulin heavy chain constant domain 4 (CH4). Heavy chains are classified as mu (p), delta (A), gamma (y), alpha (a), and epsilon (a), and define the antibody's isotype as IgM, IgD, IgG, IgA, and IgE, respectively. The IgG-class and IgA-class antibodies are further divided into subclasses, namely, IgGl, IgG2, IgG3, and IgG4, and IgAl and IgA2, respectively. The heavy chains in IgG, IgA, and IgD antibodies typically have three constant domains (CHI, CH2, and CH3), whereas the heavy chains in IgM and IgE antibodies typically have four constant domains (CHI, CH2, CH3, and CH4). The heavy chain constant domains can be from any immunoglobulin isotype, including subtypes. The antibody chains are linked together via inter-polypeptide disulfide bonds between the CL domain and the CHI domain (i.e., between the light and heavy chain) and between the hinge regions of the two antibody heavy chains.

[0044] Variable regions of immunoglobulin chains generally exhibit the same overall structure, comprising relatively conserved framework regions (FR) joined by three hypervariable regions, more often called “complementarity determining regions” or CDRs. The CDRs from the two chains of each heavy chain and light chain pair typically are aligned by the framework regions to form a structurethat binds specifically to a specific epitope on the target protein. From N-terminus to C-terminus, naturally-occurring light and heavy chain variable regions both typically conform with the following order of these elements: FR1, CDR1, FR2, CDR2, FR3, CDR3, and FR4. A numbering system has been devised for assigning numbers to amino acids that occupy positions in each of these domains. This numbering system is defined in Kabat Sequences of Proteins of Immunological Interest (1987 and 1991, NIH, Bethesda, MD), or Chothia & Lesk, 1987, J. Mol. Biol. 196:901-917; Chothia et al., 1989, Nature 342:878-883. The CDRs and FRs of a given antibody may be identified using this system. The Kabat definition is based on sequence variability, while the Chothia definition is based on the location of the structural loop regions (Chothia et al. “Conformations of immunoglobulin hypervariable regions.” Nature. 1989; 342:877-883). Alternative CDR definitions of interest include, without limitation, those disclosed by Honegger, “Yet another numbering scheme for immunoglobulin variable domains: an automatic modeling and analysis tool.” J Mol Biol. 2001;309:657-670; Ofran et al. “Automated identification of complementarity determining regions (CDRs) reveals peculiar characteristics of CDRs and B-cell epitopes.” J Immunol. 2008;181:6230-6235; Almagro “Identification of differences in the specificity-determining residues of antibodies that recognize antigens of different size: implications for the rational design of antibody repertoires.” J Mol Recognit. 2004;17: 132-143; and Padlanet al. “Identification of specificity-determining residues in antibodies.” Faseb J. 1995 ;9 : 133-139., each of which is herein specifically incorporated by reference. Other numbering systems for the amino acids in immunoglobulin chains include IMGT® (the international ImMunoGeneTics information system; Lefranc et al., Dev. Comp. Immunol. 29: 185- 203; 2005) and AHo (Honegger and Pluckthun, J. Mol. Biol. 309(3):657-670; 2001). Unless otherwise indicated, specific CDRs identified herein are defined by IMGT.

[0045] ‘ ‘Framework Region” or “FR” residues are those variable domain residues other than the hypervariable region / CDR residues as defined herein.

[0046] Antibody residues herein are numbered according to the Kabat numbering system and the EU numbering system. The Kabat numbering system is generally used when referring to a residue in the variable domain (approximately residues 1-113 of the heavy chain) (e.g., Kabat et al., Sequences of Immunological Interest. 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991)). The “EU numbering system” or “EU index” is generally used when referring to a residue in an immunoglobulin heavy chain constant region (e.g., the EU index reported in Kabat et al., supra). The “EU index as in Kabat” refers to the residue numbering of the human IgGl EU antibody. Unless stated otherwise herein, references to residue numbers in the variable domain of antibodies mean residue numbering by the Kabat numbering system. Unless stated otherwise herein, references to residue numbers in the constant domain of antibodies, single domain antibodies, antibody fragments, and the like mean residue numbering by the EU numbering system.

[0047] The term “monoclonal antibody,” as used herein, refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies comprising the population are identical except for possible naturally occurring mutations that may be present in minor amounts. In contrast to polyclonal antibody preparations which typically include different antibodies directed against different determinants (epitopes), a monoclonal antibody is generally directed against a single determinant on the antigen. As non-limiting examples, monoclonal antibodies in accordance with the present disclosure can be made by the hybridoma method first described by Kohler et al. (1975) Nature 256:495, and can also be made via recombinant protein production methods (see, e.g., U.S. Patent No. 4,816,567).

[0048] The term “human antibody,” as used herein, is intended to include antibodies having variable and constant regions derived from human germline immunoglobulin sequences. The human antibodies of the present disclosure may include amino acid residues not encoded by human germline immunoglobulin sequences (e.g., mutations introduced by random or site-specific mutagenesis in vitro or by somatic mutation in vivo). However, the term “human antibody,” as used herein, is not intended to include antibodies in which CDR sequences that are derived from the germline of another mammalian species, such as, e.g., a mouse, have been grafted onto human framework sequences.

[0049] As used herein, the term “chimeric antibody” refers to an antibody comprising amino acid sequences from at least two different Ig loci, e.g., a transgenic antibody comprising a portion encoded by a human Ig locus and a portion encoded by a rat Ig locus. Chimeric antibodies include transgenic antibodies with non-human Fc-regions or artificial Fc-regions, and human idiotypes. Such immunoglobulins can be isolated from animals of the disclosure that have been engineered to produce such chimeric antibodies.

[0050] As used herein, the term “antibody construct” refers to a molecule in which the structure and / or function is / are based on the structure and / or function of an antibody, e.g., of a full-length immunoglobulin molecule. An antibody construct binds to its target or antigen, and / or it comprises the heavy chain variable region (VH) and / or the light chain variable region (VL) of an antibody, or comprises domains derived therefrom.

[0051] As used herein, the term “heavy-chain antibody” or “heavy chain-only antibody” refers to an immunoglobulin protein consisting of two heavy chain polypeptides (such as, e.g., heavy chain polypeptides that are about 50-70 kDa each). A “heavy-chain antibody” is an antibody fragment that lacks the two light chain polypeptides found in a conventional antibody. Heavy-chain antibodies constitute about one-fourth of the IgG antibodies produced by the camelids, e.g., camels and llamas (Hamers-Casterman C., et al. Nature. 363, 446-448 (1993)). These antibodies are formed by two heavy chains but are devoid of light chains. As a consequence, the variable antigen-binding part is referred to as the VHH domain, and it represents the smallest naturally occurring, intact, antigen-binding site, being only around 120 amino acids in length (Desmyter, A., et al. J. Biol. Chem. 276, 26285-26290 (2001)). Heavy-chain antibodies with a high specificity and affinity can be generated against a variety of antigens through immunization (van der Linden, R. H., et al. Biochim. Biophys. Acta. 1431, 37-46 (1999)), and the VHH portion can be readily cloned and expressed in yeast (Frenken, L. G. J., et al. J. Biotechnol. 78, 11-21 (2000)). Their levels of expression, solubility and stability are significantly higher than those of classical F(ab) or Fv fragments (Ghahroudi, M. A. et al. FEBSLett. 414, 521-526 (1997)). Sharks have also been shown to have a single VH-like domain in their antibodies, termed VNAR. (Nuttall et al. Eur. J. Biochem. 270, 3543-3554 (2003); Nuttall et al. Function and Bioinformatics 55, 187-197 (2004); Dooley et al., Molecular Immunology 40, 25-33 (2003).)

[0052] In some embodiments, a “heavy-chain antibody” is a homodimeric antibody comprising a VH antigen-binding domain and the CH2 and CH3 constant domains, in the absence of the CHI domain. In some embodiments, a heavy-chain antibody is composed of a variable region antigen-binding domain composed of framework 1, CDR1, framework 2, CDR2, framework 3, CDR3, and framework 4. In some embodiments, a heavy-chain antibody is composed of an antigenbinding domain, at least part of a hinge region, and CH2 and CH3 domains (e.g., in the absence of a CHI domain). In some embodiments, a heavy-chain antibody is composed of an antigen-binding domain, at least part of a hinge region, and a CH2 domain. In some embodiments, a heavy-chain antibody is composed of an antigen-binding domain, at least part of a hinge region, and a CH3 domain. Heavy-chain antibodies in which the CH2 and / or CH3 domain is truncated are also included herein. The heavy-chain antibodies described herein may belong to the IgG subclass, but heavy-chain antibodies belonging to other subclasses, such as IgM, IgA, IgD, and IgE subclass, are also included herein. In some embodiments, a heavy-chain antibody may belong to the IgGl, IgG2, IgG3, or IgG4 subtype, e.g., the IgGl or IgG4 subtype. In some embodiments, a heavy-chain antibody is of the IgGl or IgG4 subtype, wherein one or more of the CH domains is modified to alter an effector function of the heavy-chain antibody. In some embodiments, a heavy-chain antibody is of the IgG4 subtype, wherein one or more of the CH domains is modified to alter an effector function of the heavy-chain antibody. In some embodiments, a heavy-chain antibody is of the IgGl subtype, wherein one or more of the CH domains is modified to alter an effector function of the heavy-chain antibody.Modifications of CH domains that alter effector function are further described herein. Non-limiting examples of heavy-chain antibodies are described, for example, in WO2018 / 039180, the disclosure of which is incorporated herein by reference herein in its entirety.

[0053] As used herein, an “antibody fragment” generally refers to a fragment of a full-length antibody or heavy-chain antibody, such as, e.g., VH, VHH, VL, (s)dAb, Fv, light chain (VL-CL), Fd (VH-CH1), heavy chain, Fab, Fab’, F(ab')2 or “r IgG” (“half antibody” consisting of a heavy chain and a light chain) or a modified fragment of a full-length antibody, such as, e.g., three-chain antibody-like molecule, heavy-chain only antibody, single-chain variable fragment (scFv), di-scFv or bi(s)-scFv, scFv-Fc, scFv-zipper, single-chain Fab (scFab), Fab2, Fab;, diabodies, single-chain diabodies, tandem diabodies (Tandabs), tandem di-scFv, tandem tri-scFv, “minibodies” exemplified by a structure which is as follows: (VH-VL-CH3)2, (scFv-CH3)2 , ((scFv)2-CH3 + CH3), ((scFv)2- CH3) or (SCFV-CH3-SCFV)2, multibodies, such as triabodies or tetrabodies, and single domain antibodies, such as nanobodies or single variable domain antibodies comprising merely one variable region, which might be VHH, VH or VL, that binds to an antigen or target independently of other variable regions or domains.

[0054] As used herein, a “single domain antibody” refers to a single polypeptide chain that contains all or part of the heavy chain variable domain or all or part of the light chain variable domain of an antibody. In some embodiments, the single domain antibody is a human single domain antibody.

[0055] As used herein, the term “three-chain antibody like molecule, ” “TCA” or “three-chain antibody fragment” refers to antibody-like molecules or antibody fragments comprising, consisting essentially of, or consisting of three polypeptide subunits, two of which comprise, consist essentially of, or consist of one heavy and one light chain of a monoclonal antibody, or antigen-binding fragments of such antibody chains, comprising an antigen-binding region and at least one CH domain. This heavy chain / light chain pair has binding specificity for a first antigen. The third polypeptide subunit comprises, consists essentially of, or consists of a heavy chain polypeptide comprising an Fc portion comprising CH2 and / or CH3 and / or CH4 domains, in the absence of a CHI domain, and one or more antigen binding domains (such as, e.g., two antigen binding domains) that binds an epitope of a second antigen or a different epitope of the first antigen, wherein such binding domain is derived from or has sequence identity with the variable region of an antibody heavy chain.

[0056] As used herein, an “antigen-binding fragment” is a portion of an antibody or a heavy-chain antibody that lacks at least some of the amino acids present in a heavy chain (in the case of an antibody or heavy-chain antibody) and / or light chain (in the case of an antibody), but which is still capable of specifically binding to an antigen. An antigen-binding fragment includes, but is not limited to, a single-chain variable fragment (scFv), a nanobody (e.g., VH domain of camelid heavy-chain antibodies; VHH fragment, see Cortez-Retamozo et al., Cancer Research, Vol. 64:2853-57, 2004), a Fab fragment, a Fab' fragment, a F(ab')2 fragment, a Fv fragment, a Fd fragment, and a CDR fragment, and can be derived from any mammalian source, such as human, mouse, rat, rabbit, or camelid.

[0057] Papain digestion of antibodies produces two identical antigen-binding fragments, called “Fab” fragments, each with a single antigen-binding site, and a residual “Fc” fragment which contains all but the first domain of the immunoglobulin heavy chain constant region. The Fab fragment contains the variable domains from the light and heavy chains, as well as the constant domain of thelight chain and the first constant domain (CHI) of the heavy chain. Thus, a “Fab fragment” is comprised of one immunoglobulin light chain (light chain variable region (VL) and constant region (CL)) and the CHI domain and variable region (VH) of one immunoglobulin heavy chain. The heavy chain of a Fab molecule cannot form a disulfide bond with another heavy chain molecule. The “Fd fragment” comprises the VH and CHI domains from an immunoglobulin heavy chain. The Fd fragment represents the heavy chain component of the Fab fragment.

[0058] As used herein, an “Fc region” may be a native-sequence Fc region or a variant Fc region. An “Fc region,” as used herein, may comprise a hinge region. The “Fc region” of an immunoglobulin generally comprises two constant domains, a CH2 domain and a CH3 domain, and optionally comprises a CH4 domain. In some embodiments, the Fc region may be an Fc region from an IgGl, IgG2, IgG3, or IgG4 immunoglobulin. In some embodiments, the Fc region comprises CH2 and CH3 domains from a human IgGl or human IgG2 immunoglobulin. In some embodiments, the Fc region comprises a hinge region, a CH2 domain, and a CH3 domain. The Fc region may retain effector function, such as Clq binding, complement dependent cytotoxicity (CDC), Fc receptor binding, antibody-dependent cell-mediated cytotoxicity (ADCC), and phagocytosis. In other embodiments, the Fc region may be modified to reduce or eliminate effector function.

[0059] A “functional Fc region” possesses an “effector function” of a native-sequence Fc region. Non-limiting examples of effector functions include Clq binding, CDC; Fc-receptor binding, ADCC, ADCP, down-regulation of cell-surface receptors (e.g., B-cell receptor), etc. Such effector functions generally require the Fc region to interact with a receptor, such as, e.g., the FcyRI; FcyRIIA; FcyRIIBl; FcyRIIB2; FcyRIIIA; FcyRIIIB receptors, and the low affinity FcRn receptor; and can be assessed using various assays known in the art.

[0060] A “dead” or “silenced” Fc is one that has been mutated to retain activity with respect to, for example, prolonging serum half-life, but which does not activate a high affinity Fc receptor, or which has a reduced affinity to an Fc receptor.

[0061] A “native-sequence Fc region” comprises an amino acid sequence identical to the amino acid sequence of an Fc region found in nature. Native-sequence human Fc regions include, for example, a native-sequence human IgGl Fc region (non-A and A allotypes); native-sequence human IgG2 Fc region; native-sequence human IgG3 Fc region; and native -sequence human IgG4 Fc region, as well as naturally occurring variants thereof.

[0062] A “variant Fc region” comprises an amino acid sequence that differs from that of a nativesequence Fc region by virtue of at least one amino acid modification, for example, one or more (e.g., two or more, three or more, four or more) amino acid substitution(s). Illustratively, in some embodiments, the variant Fc region has at least one amino acid substitution compared to a nativesequence Fc region or to the Fc region of a parent polypeptide, e.g., from one to ten amino acidsubstitutions, e.g., from one to five amino acid substitutions in a native-sequence Fc region or in the Fc region of the parent polypeptide. In some embodiments, the variant Fc region herein will possess at least 80% homology with a native -sequence Fc region and / or with an Fc region of a parent polypeptide, e.g., at least 85% homology therewith, e.g., at least 90% homology therewith, e.g., at least 95% homology therewith, e.g., at least 99% homology therewith.

[0063] As used herein, “heterodimerizing alterations” refer to alterations in the A and B chains of an Fc region (i.e., the two chains comprising the Fc region, wherein one chain is referred to herein as the “A” chain and the other is referred to herein as the “B” chain) that facilitate the formation of heterodimeric Fc regions, that is, Fc regions in which the A chain and the B chain of the Fc region do not have identical amino acid sequences. In some embodiments, heterodimerizing alterations can be asymmetric, that is, an A chain having a certain alteration can pair with a B chain having a different alteration. These alterations facilitate heterodimerization and disfavor homodimerization. Whether hetero- or homo-dimers have formed can be assessed, for example, by size differences as determined by polyacrylamide gel electrophoresis in situations where one polypeptide chain is a dummy Fc and the other is an scFv-Fc. One non-limiting example of such paired heterodimerizing alterations are the so-called "knobs and holes" substitutions. See, e.g., U.S. Patent No. 7,695,936 and U.S. Patent Application Publication No. 2003 / 0078385. As used herein, an Fc region that comprises one pair of knobs and holes substitutions, comprises one substitution in the A chain and another in the B chain. For example, the following knobs and holes substitutions in the A and B chains of an IgGl Fc region have been found to increase heterodimer formation as compared with that found with unmodified A and B chains and may be employed in some non-limiting embodiments of this disclosure: 1) Y407T in one chain and T366Y in the other; 2) Y407A in one chain and T366W in the other; 3) F405A in one chain and T394W in the other; 4) F405W in one chain and T394S in the other; 5) Y407T in one chain and T366Y in the other; 6) T366Y and F405A in one chain and T394W and Y407T in the other; 7) T366W and F405W in one chain and T394S and Y407A in the other; 8) F405W and Y407A in one chain and T366W and T394S in the other; and 9) T366W in one polypeptide of the Fc and T366S, U368A, and Y407V in the other. Alternatively or in addition to such alterations, substitutions creating new disulfide bridges can facilitate heterodimer formation. See, e.g., U.S. Patent Application Publication No. 2003 / 0078385. Such alterations in an IgGl Fc region include, but are not limited to, the following substitutions: Y349C in one Fc polypeptide chain and S354C in the other; Y349C in one Fc polypeptide chain and E356C in the other; Y349C in one Fc polypeptide chain and E357C in the other; L351C in one Fc polypeptide chain and S354C in the other; T394C in one Fc polypeptide chain and E397C in the other; or D399C in one Fc polypeptide chain and K392C in the other. Additionally or alternatively, substitutions changing the charge of a one or more residue(s), for example, in the CH3-CH3 interface, can enhance heterodimer formation, as described, for example, in WO 2009 / 089004, which is incorporated by reference herein. Such substitutions are referred to hereinas “charge pair substitutions,” and an Fc region comprising one pair of charge pair substitutions comprises one substitution in the A chain and a different substitution in the B chain. Non-limiting examples of charge pair substitutions include the following: 1) K409D or K409E in one chain plus D399K or D399R in the other; 2) K392D or K392E in one chain plus D399K or D399R in the other; 3) K439D or K439E in one chain plus E356K or E356R in the other; and 4) K370D or K370E in one chain plus E357K or E357R in the other. In addition, the substitutions R355D, R355E, K360D, or K360R in both chains can stabilize heterodimers when used with other heterodimerizing alterations. Specific charge pair substitutions can be used either alone or with other charge pair substitutions. Specific examples of single pairs of charge pair substitutions and combinations thereof include, but are not limited to, the following: 1) K409E in one chain plus D399K in the other; 2) K409E in one chain plus D399R in the other; 3) K409D in one chain plus D399K in the other; 4) K409D in one chain plus D399R in the other; 5) K392E in one chain plus D399R in the other; 6) K392E in one chain plus D399K in the other; 7) K392D in one chain plus D399R in the other; 8) K392D in one chain plus D399K in the other; 9) K409D and K360D in one chain plus D399K and E356K in the other; 10) K409D and K370D in one chain plus D399K and E357K in the other; 11) K409D and K392D in one chain plus D399K, E356K, and E357K in the other; 12) K409D and K392D on one chain and D399K on the other; 13) K409D and K392D on one chain plus D399K and E356K on the other; 14) K409D and K392D on one chain plus D399K and D357K on the other; 15) K409D and K370D on one chain plus D399K and D357K on the other; 16) D399K on one chain plus K409D and K360D on the other; and 17) K409D and K439D on one chain plus D399K and E356K on the other. In some embodiments, any of these heterodimerizing alterations can be used in polypeptides comprising variant Fc regions as described herein.

[0064] In some non-limiting embodiments, variant Fc sequences may include three amino acid substitutions in the CH2 region to reduce FcyRI binding at EU index positions 234, 235, and 237 (see Duncan et al., (1988) Nature 332:563). Two amino acid substitutions in the complement Clq binding site at EU index positions 330 and 331 reduce complement fixation (see Tao et al., J. Exp. Med.178:661 (1993) and Canfield and Morrison, J. Exp. Med. 173: 1483 (1991)). Substitution into human IgGl or IgG2 residues at positions 233-236 and IgG4 residues at positions 327, 330, and 331 can reduce ADCC and CDC (see, for example, Armour KL. et al., 1999 Eur J Immunol. 29(8):2613-24; and Shields R.L. et al., 2001. J Biol Chem. 276(9): 6591 -604). Silenced IgGl is described, for example, in Boesch, A.W., et al., “Highly parallel characterization of IgG Fc binding interactions.” MAbs, 2014. 6(4): p. 915-27, the disclosure of which is incorporated herein by reference in its entirety.

[0065] Further, an Fc variant can be constructed to remove or substantially reduce effector functions by substituting (mutating), deleting, or adding amino acid residues to effect complement binding or Fc receptor binding. For example, and not by way of limitation, a deletion may occur in acomplement-binding site, such as a Clq-binding site. Techniques for preparing such sequence derivatives of the immunoglobulin Fc fragment are disclosed in International Patent Publication Nos. WO 97 / 34631 and WO 96 / 32478. In addition, the Fc domain may be modified by phosphorylation, sulfation, acylation, glycosylation, methylation, famesylation, acetylation, amidation, and the like.

[0066] Antibodies and antibody fragments with reduced effector function include, but are not limited to, those with substitution of one or more of Fc region residues 238, 265, 269, 270, 297, 327, and 329, according to EU numbering (see, e.g., U.S. Patent No. 6,737,056). In some embodiments, variant Fc regions with reduced effector function comprise substitutions at two or more of amino acid positions 265, 269, 270, 297, and 327, according to EU numbering, including the so-called “DANA” Fc mutant with substitution of residues 265 and 297 to alanine according to EU numbering (i.e., D265A and N297A according to EU numbering) (see, e.g., U.S. Patent No. 7,332,581). In some embodiments, a variant Fc region with reduced effector function comprises the following two amino acid substitutions: D265A and N297A.

[0067] In some embodiments, effector function is reduced through a mutation in a constant region that eliminates glycosylation, e.g., an “effector-less mutation.” In some embodiments, the effector-less mutation is an N297A or a DANA mutation (D265A+N297A) in the CH2 region. Shields et al., J. Biol. Chem. 276 (9): 6591-6604 (2001). In some embodiments, the effector-less mutation is an N297G or a DANG mutation (D265A+N297G) in the CH2 region. In some embodiments, the variant Fc region lacks glycosylation at N297, e.g., the variant Fc region is a variant Fc region lacking glycosylation at N297 as described in International Patent Publication No. WO 2014 / 153063, which is incorporated by reference herein. Alternatively, additional mutations resulting in reduced or eliminated effector function include: K322A and L234A / L235A (LALA). Alternatively, effector function can be reduced or eliminated through production techniques, such as expression in host cells that do not glycosylate (e.g., E. coli) or in host cells which result in an altered glycosylation pattern that is ineffective or less effective at promoting effector function (e.g., Shinkawa et al., J. Biol. Chem. 278(5): 3466-3473 (2003)).

[0068] In some embodiments, the proline at position 329 (EU numbering) (P329) of a wild-type human Fc region is substituted with glycine or arginine or an amino acid residue large enough to destroy the proline sandwich within the Fc / Fcy receptor interface, that is formed between the P329 of the Fc and tryptophan residues W87 and W110 of FcyRIII (Sondermann et al., Nature 406, 267-273 (20 Jul. 2000)). In some further embodiments, at least one further amino acid substitution in the Fc variant region is S228P, E233P, L234A, L235A, L235E, N297A, N297D, or P331S. In some embodiments, the at least one further amino acid substitution is L234A and L235A of the human IgGl Fc region or S228P and L235E of the human IgG4 Fc region, all according to EU numbering (see, e.g., U.S. Patent No. 8,969,526, which is incorporated by reference in its entirety).

[0069] In some embodiments, the variant Fc region has P329 of the human IgG Fc region substituted with glycine, wherein the variant Fc region comprises at least two further amino acid substitutions at L234A and L235A of the human IgGl Fc region or S228P and L235E of the human IgG4 Fc region, and wherein the residues are numbered according to the EU numbering (see, e.g., U.S. Patent No. 8,969,526). In some embodiments, the variant Fc region comprising the P329G, L234A and L235A (EU numbering) substitutions exhibits a reduced affinity to the human FcyRIIIA and FcyRIIA.

[0070] In some embodiments, the variant Fc region comprises a triple mutation: an amino acid substitution at position P329, a L234A, and a L235A mutation according to EU numbering (P329 / LALA) (see, e.g., U.S. Patent No. 8,969,526). In some embodiments, the variant Fc region comprises the following amino acid substitutions: P329G, L234A, and L235A according to EU numbering.

[0071] In some embodiments, an antibody, heavy-chain antibody, or antibody fragment comprises a variant human IgG4 CH3 domain sequence comprising a T366W mutation, which can optionally be referred to herein as an IgG4 CH3 knob sequence. In some embodiments, an antibody, heavy-chain antibody, or antibody fragment comprises a variant human IgG4 CH3 domain sequence comprising a T366S mutation, an L368A mutation, and a Y407V mutation, which can optionally be referred to herein as an IgG4 CH3 hole sequence. The IgG4 CH3 mutations described herein can be utilized in any suitable manner so as to place a “knob” on a first heavy chain constant region of a first monomer in an antibody dimer, and a “hole” on a second heavy chain constant region of a second monomer in an antibody dimer, thereby facilitating proper pairing (heterodimerization) of the desired pair of heavy chain polypeptide subunits in the antibody.

[0072] In some embodiments, an antibody, heavy-chain antibody, or antibody fragment comprises a heavy chain polypeptide subunit comprising a variant human IgG4 Fc region comprising an S228P mutation, an F234A mutation, an L235A mutation, and a T366W mutation (knob). In some embodiments, an antibody, heavy-chain antibody, or antibody fragment comprises a heavy chain polypeptide subunit comprising a variant human IgG4 Fc region comprising an S228P mutation, an F234A mutation, an L235A mutation, a T366S mutation, an L368A mutation, and a Y407V mutation (hole).

[0073] As used herein, a “Fab1fragment” is a Fab fragment having at the C-terminus of the CHI domain one or more cysteine residues from the antibody hinge region.

[0074] As used herein, a “F(ab')2 fragment” is a bivalent fragment including two Fab' fragments linked by a disulfide bridge between the heavy chains at the hinge region.

[0075] As used herein, a “Fv” fragment is the minimum fragment that contains a complete antigen recognition and binding site from an antibody. This fragment consists of a dimer of one immunoglobulin heavy chain variable region (VH) and one immunoglobulin light chain variable region (VL) in tight, non-covalent association. It is in this configuration that the three CDRs of each variable region interact to define an antigen binding site on the surface of the VH-VL dimer. A single light chain or heavy chain variable region (or half of an Fv fragment comprising only three CDRs specific for an antigen) has the ability to recognize and bind antigen, although at a lower affinity than the entire binding site comprising both VH and VL.

[0076] As used herein, a “single-chain variable fragment” or “scFv fragment” comprises the VH and VL regions of an antibody, wherein these regions are present in a single polypeptide chain, and optionally comprises a peptide linker between the VH and VL regions that enables the Fv to form the desired structure for antigen binding (see e.g., Bird et al., Science, Vol. 242:423-426, 1988; and Huston et al., Proc. Natl. Acad. Sci. USA, Vol. 85:5879-5883, 1988).

[0077] A “nanobody” is the heavy chain variable region of a heavy-chain antibody. Such variable domains are the smallest fully functional antigen-binding fragment of such heavy-chain antibodies with a molecular mass of only about 15 kDa. See Cortez-Retamozo et al., Cancer Research 64:2853- 57, 2004. Functional heavy-chain antibodies devoid of light chains are naturally occurring in certain species of animals, such as nurse sharks, wobbegong sharks, and Camelidae, such as camels, dromedaries, alpacas and llamas. The antigen-binding site is reduced to a single domain, the VHH domain, in these animals. These antibodies form antigen-binding regions using only heavy chain variable region, i.e., these functional antibodies are homodimers of heavy chains only having the structure H2L2 (referred to as “heavy-chain antibodies” or “HCAbs”). Camelized VHH reportedly recombines with IgG2 and IgG3 constant regions that contain hinge, CH2, and CH3 domains and lack a CHI domain. Camelized VHH domains have been found to bind to antigen with high affinity (Desmyter et al., J. Biol. Chem., Vol. 276:26285-90, 2001) and possess high stability in solution (Ewert et al., Biochemistry, Vol. 41:3628-36, 2002). Methods for generating antibodies having camelized heavy chains are described in, for example, U.S. Patent Publication Nos. 2005 / 0136049 and 2005 / 0037421. Alternative scaffolds can be made from human variable-like domains that more closely match the shark V-NAR scaffold and may provide a framework for a long penetrating loop structure.

[0078] Antibodies, heavy-chain antibodies, and antibody fragments of the present disclosure may be multispecific, meaning they possess more than one binding specificity. As used herein, the term “multi-specific” includes “bispecific” (i.e., two binding specificities) and “trispecific” (i.e., three binding specificities), as well as higher-order independent specific binding affinities, such as higher-order polyepitopic specificity.

[0079] As used herein, an “isolated” molecule (such as, e.g., an antibody, heavy-chain antibody, antibody fragment, single domain antibody) is a molecule which has been identified and separated and / or recovered from a component of its natural environment. Contaminant components of its natural environment are materials which may interfere with diagnostic or therapeutic uses for the molecule, such as, e.g., enzymes, hormones, and other proteinaceous or non-proteinaceous solutes. In some embodiments, the isolated molecule will be purified (1) to greater than 95% by weight of the molecule as determined by the Lowry method, such as, e.g., more than 99% by weight, (2) to a degree sufficient to obtain at least 15 residues of N-terminal or internal amino acid sequence by use of a spinning cup sequenator, or (3) to homogeneity by SDS-PAGE under reducing or nonreducing conditions using Coomassie blue or, e.g., silver stain. In some embodiments, an isolated molecule will be prepared by a process comprising at least one purification step.

[0080] Aspects of the present disclosure include antibodies, heavy-chain antibodies, and antibody fragments comprising a heavy chain-only variable region in a monovalent or bivalent configuration. As used herein, the term “monovalent configuration,” as used in reference to a heavy chain-only variable region domain, means that only one heavy chain-only variable region domain is present, having a single binding site. In contrast, the term “bivalent configuration” as used in reference to a heavy chain-only variable region domain means that two heavy chain-only variable region domains are present (each having a single binding site), and are connected by a linker sequence. Non-limiting examples of linker sequences are discussed further herein, and include, without limitation, GS linker sequences of various lengths. When a heavy chain-only variable region is in a bivalent configuration, each of the two heavy chain-only variable region domains can bind to the same antigen, or to different antigens (e.g., to different epitopes on the same protein; to two different proteins, etc.). However, unless specifically noted otherwise, a heavy chain-only variable region denoted as being in a “bivalent configuration” is understood to contain two identical heavy chain-only variable region domains, connected by a linker sequence, wherein each of the two identical heavy chain-only variable region domains binds to the same target antigen.

[0081] Aspects of the present disclosure also include antibodies, heavy-chain antibodies, and antibody fragments having multi-specific configurations, which include, without limitation, bispecific, trispecific, etc. configurations. A large variety of methods and protein configurations are known and used in bispecific monoclonal antibodies (BsMAB), tri-specific antibodies, etc.

[0082] Various methods for the production of multivalent artificial antibodies have been developed by recombinantly fusing variable domains of two or more antibodies. In some embodiments, a first and a second antigen-binding domain on a polypeptide are connected by a polypeptide linker. One non-limiting example of such a polypeptide linker is a GS linker, having an amino acid sequence of four glycine residues, followed by one serine residue, and wherein the sequence is repeated n times,where n is an integer ranging from 1 to 10 (SEQ ID NO: 42), such as 2, 3, 4, 5, 6, 7, 8, or 9. Nonlimiting examples of such linkers include GGGGS (SEQ ID NO: 43) (n=l) and GGGGSGGGGS (SEQ ID NO: 44) (n=2). Other suitable linkers can also be used, and are described, for example, in Chen et al., Adv Drug Deliv Rev. 2013 October 15; 65(10): 1357-69, the disclosure of which is incorporated herein by reference in its entirety.

[0083] As used herein, the term “amino acid” or “amino acid residue” refers to an amino acid having its art recognized definition, such as, e.g., an amino acid selected from the group consisting of: alanine (Ala or A); arginine (Arg or R); asparagine (Asn or N); aspartic acid (Asp or D); cysteine (Cys or C); glutamine (Gin or Q); glutamic acid (Glu or E); glycine (Gly or G); histidine (His or H); isoleucine (He or I): leucine (Leu or L); lysine (Lys or K); methionine (Met or M); phenylalanine (Phe or F); pro line (Pro or P); serine (Ser or S); threonine (Thr or T); tryptophan (Trp or W); tyrosine (Tyr or Y); and valine (Vai or V), although modified, synthetic, or rare amino acids may be used as desired. Generally, amino acids can be grouped as having a nonpolar side chain (e.g., Ala, Cys, He, Leu, Met, Phe, Pro, Vai); a negatively charged side chain (e.g., Asp, Glu); a positively charged sidechain (e.g., Arg, His, Lys); or an uncharged polar side chain (e.g., Asn, Cys, Gin, Gly, His, Met, Phe, Ser, Thr, Trp, and Tyr).

[0084] As used herein, “amino acid modifications” include, but are not limited to, deletions from, and / or insertions into, and / or substitutions of, residues within an amino acid sequence. Any combination of deletion, insertion, and substitution may be made to arrive at a final construct, provided that the final construct possesses the desired characteristics. The amino acid changes also may alter post-translational processes of the antibody constructs, such as changing the number or position of glycosylation sites. Non-limiting example substitutions (or replacements) are conservative substitutions. However, any substitution (including non-conservative substitutions) is envisaged as long as the final construct retains its capability to bind to the target antigen.

[0085] One of skill in the art will realize that conservative variants of the antibodies, heavy-chain antibodies, antibody fragments, and antigen-binding fragments thereof described herein can be produced. Such conservative variants employed in antibody fragments, such as dsFv fragments or in scFv fragments, will retain critical amino acid residues necessary for correct folding and stabilizing between the VH and the VL regions, and will retain the charge characteristics of the residues in order to preserve the low pl and low toxicity of the molecules. In some embodiments, amino acid substitutions (such as, e.g., at most one, at most two, at most three, at most four, or at most five amino acid substitutions) can be made in the VH and / or the VL regions to increase yield. Conservative amino acid substitution tables providing functionally similar amino acids are well-known to one of ordinary skill in the art, such as, e.g., those described in TABLE 1.TABLE 1. Example Conservative Substitutions

[0086] As used herein, “% identical,” “percent (%) amino acid sequence identity,” or “percent (%) sequence identity,” with respect to a reference polypeptide sequence, is defined as the percentage of amino acid residues in a candidate sequence that are identical with the amino acid residues in the reference polypeptide sequence, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity, and not considering any conservative substitutions as part of the sequence identity. Alignment for purposes of determining percent amino acid sequence identity can be achieved in various ways that are within the skill in the art, for instance, using publicly available computer software such as BLAST, BLAST-2, ALIGN or Megalign (DNASTAR) software. Those skilled in the art can determine appropriate parameters for aligning sequences, including any algorithms needed to achieve maximal alignment over the full length of the sequences being compared. Lor purposes herein, however, % amino acid sequence identity values are generated using the sequence comparison computer program ALIGN-2.

[0087] As used herein, the term “cancer” refers to various conditions caused by the abnormal, uncontrolled growth of cells and includes neoplasms, primary tumors, secondary tumors, and other metastatic lesions. Cancer can be detected in a number of ways including, but not limited to, the presence of a tumor in a tissue as detected by clinical or radiological means, detection of cancerous orabnormal cells in a biological sample (e.g., tissue biopsy), detection of a biomarker indicative of a cancer or a pre-cancerous condition, or detection of a genotype indicative of cancer or the risk of developing cancer. The term “cancer” encompasses various cancerous conditions regardless of stage, grade, invasiveness, aggressiveness, or tissue type. Cancers that may be treated according to the methods of the present disclosure include, but are not limited to, leukemia (e.g., myeloid leukemia, chronic lymphocytic leukemia, chronic myelogenous leukemia, acute lymphoblastic leukemia), lymphoma (e.g., diffuse large B-cell lymphoma, Burkitt lymphoma, Non-Hodgkin lymphoma, follicular lymphoma), multiple myeloma, lung cancer (e.g., small-cell lung cancer (SCLC), non-small cell lung cancer (NSCLC)), glioma, glioblastoma, melanoma, prostate cancer (e.g., castration-resistant prostate cancer, neuroendocrine prostate cancer), pancreatic cancer, breast cancer, bone cancer, cervical cancer, colon cancer, colorectal cancer, endometrial cancer, head and neck cancer, liver cancer, ovarian cancer, gastric cancer, gastroesophageal junction cancer, testicular cancer, thyroid cancer, adrenal cancer, renal cancer, bladder cancer, uterine cancer, esophageal cancer, urothelial cancer, carcinoma, and sarcoma, and metastatic cancer derived from any of the foregoing.

[0088] As used herein, the term “anti-cancer effect” refers to a biological effect which can be manifested by various means, including but not limited to, e.g., a decrease in tumor volume, a decrease in the number of cancer cells, a decrease in the number of metastases, an increase in life expectancy, decrease in cancer cell proliferation, decrease in cancer cell survival, or amelioration of various physiological symptoms associated with the cancerous condition. An “anti-cancer effect” can also be manifested by prevention of the occurrence of cancer in the first place. As used herein, the term “anti-tumor effect” refers to a biological effect which can be manifested by various means, including but not limited to, e.g., a decrease in tumor volume, a decrease in the number of tumor cells, a decrease in tumor cell proliferation, or a decrease in tumor cell survival.

[0089] The terms “IL2” and “IL-2,” as used interchangeably herein, refer to interleukin-2, which is a 15.5 to 16 kDa cytokine signaling protein molecule that regulates the activity of certain immune cells by binding to IL2 receptor complexes expressed by lymphocytes. The term “IL2” includes an IL2 protein of any human and non-human animal species, and specifically includes human IL2 as well as IL2 of non-human mammals. The human IL-2 sequence (UniProtKB No. P60568) is provided herein as SEQ ID NO: 48. The term “human IL2” as used herein includes any variants, isoforms, and species homologs of human IL2, regardless of its source or mode of preparation. Thus, “human IL2” includes human IL2 naturally expressed by cells and IL2 expressed on cells transfected with the human IL2 gene.

[0090] The terms “IL2R,” “IL-2R,” “IL2 receptor,” and “IL-2 receptor,” as used interchangeably herein, refer generally to the IL2 receptor complex, which is composed of three polypeptide subunits, or chains, referred to as the alpha, A, or a chain, the beta, B, or [3 chain, and the gamma, G, or y chain.IL-2R is a heterodimeric protein expressed on the surface of various immune cells, which serves as a cognate ligand for interleukin 2 (IL-2). The term “IL2R” includes any IL2R protein or any subunit of the IL2 receptor complex, of any human and non-human animal species, and specifically includes human IL2R as well as IL2R of non-human mammals. The term “human IL2R” as used herein includes any variants, isoforms, and species homologs of human IL2R, regardless of its source or mode of preparation. Thus, “human IL2R” includes human IL2R naturally expressed by cells and IL2R expressed on cells transfected with the human IL2R gene.

[0091] The term “IL2RA” or “IL2Ra” is also referred to as CD25, and the human IL2RA sequence (UniProtKB No. P01589) is provided herein as SEQ ID NO: 45.

[0092] The term “IL2RB” or “IL2RP” is also referred to as CD 122, and the human IL2RB sequence (UniProtKB No. P 14784) is provided herein as SEQ ID NO: 46.

[0093] The term “IL2RG” or “IL2Ry” is also referred to as CD 132, and the human IL2RG sequence (UniProtKB No. P31785) is provided herein as SEQ ID NO: 47.

[0094] The terms “anti-IL2R heavy chain-only antibody,” “IL2R heavy chain-only antibody,” “anti-IL2R heavy chain antibody,” and “IL2R heavy chain antibody” are used herein interchangeably to refer to a heavy-chain antibody as hereinabove defined, that binds to IL2R, including human IL2R, as hereinabove defined. The definition includes, without limitation, human heavy-chain antibodies produced by transgenic animals, such as transgenic rats or transgenic mice expressing human immunoglobulin, including UniRats™ producing human anti-IL2R UniAb™ antibodies. Similarly, as used herein, the term “anti-IL2RPy heavy chain-only antibody” or “anti-IL2RPy heavy-chain antibody” refers to a heavy-chain antibody that binds to IL2RP and IL2Ry.

[0095] As used herein, the term “agonist” refers to a molecule that causes an increase in a function or activity as compared to the same function or activity in the absence of the molecule. An “agonist” of a signaling pathway is therefore a molecule whose presence causes an increase in a function or activity of the signaling pathway. The term “agonize,” as used herein, refers to causing an increase in a function or activity. In some embodiments, the agonist function of an antibody, antibody fragment, or antigen-binding fragment thereof may be determined using an assay described herein.

[0096] As used herein, an “epitope” is the site on the surface of an antigen molecule to which a single antigen-binding molecule binds. Generally, an antigen has several or many different epitopes and reacts with many different antibodies. The term specifically includes linear epitopes and conformational epitopes.

[0097] The term “valent,” as used herein, refers to a specified number of binding sites in a molecule.

[0098] A “monovalent” antibody has one binding site. Thus, a monovalent antibody is also monospecific.

[0099] A “multi-valent” antibody has two or more binding sites. Thus, the terms “bivalent,” “trivalent,” and “tetravalent” refer to the presence of two binding sites, three binding sites, and four binding sites, respectively. Thus, a bispecific antibody according to the disclosure is at least bivalent and may be trivalent, tetravalent, or otherwise multi-valent. A bivalent antibody in accordance with embodiments of the disclosure may have two binding sites to the same epitope (i.e., bivalent, monoparatopic), or to two different epitopes (i.e., bivalent, biparatopic).

[0100] A large variety of methods and protein configurations are known and used for the preparation of bispecific monoclonal antibodies (BsMAB), tri-specific antibodies, and the like.

[0101] As used herein, the term “effector cell” refers to an immune cell which is involved in the effector phase of an immune response, as opposed to the cognitive and activation phases of an immune response. Some effector cells express specific Fc receptors and carry out specific immune functions. In some embodiments, an effector cell such as a natural killer cell is capable of inducing antibody-dependent cellular cytotoxicity (ADCC). For example, monocytes and macrophages, which express FcR, are involved in specific killing of target cells and presenting antigens to other components of the immune system, or binding to cells that present antigens. In some embodiments, an effector cell may phagocytose a target antigen or target cell.

[0102] “Human effector cells” are leukocytes which express receptors such as T-cell receptors or FcRs and perform effector functions. For example, in some embodiments, the cells express at least FcyRIII and perform ADCC effector function. Non-limiting examples of human leukocytes which mediate ADCC include natural killer (NK) cells, monocytes, cytotoxic T-cells, and neutrophils. The effector cells may be isolated from a native source thereof, e.g., from blood or PBMCs as described herein.

[0103] The term “immune cell” is used herein in the broadest sense, including, without limitation, cells of myeloid or lymphoid origin, for instance, lymphocytes (such as B-cells and T-cells including cytolytic T-cells (CTLs)), killer cells, natural killer (NK) cells, macrophages, monocytes, eosinophils, polymorphonuclear cells, such as neutrophils, granulocytes, mast cells, and basophils.

[0104] Antibody “effector functions” refer to those biological activities attributable to the Fc region (a native sequence Fc region or amino acid sequence variant Fc region) of an antibody. Examples of antibody effector functions include, but are not limited to, Clq binding; complement dependent cytotoxicity (CDC); Fc receptor binding; antibody-dependent cell-mediated cytotoxicity (ADCC); phagocytosis; down regulation of cell surface receptors (e.g., B-cell receptor; BCR), etc.

[0105] “Antibody-dependent cell-mediated cytotoxicity” and “ADCC” refer to a cell-mediated reaction in which nonspecific cytotoxic cells that express Fc receptors (FcRs) (e.g., Natural Killer (NK) cells, neutrophils, and macrophages) recognize bound antibody on a target cell and subsequently cause lysis of the target cell. The primary cells for mediating ADCC, NK cells, express FcyRIII only, whereas monocytes express FcyRI, FcyRII and FcyRIII. FcR expression on hematopoietic cells is summarized in Table 3 on page 464 of Ravetch and Kinet, Annu. Rev. Immunol 9:457-92 (1991). To assess ADCC activity of a molecule of interest, an in vitro ADCC assay, such as that described in US Patent Nos. 5,500,362 or 5,821,337 may be performed. Useful effector cells for such assays include peripheral blood mononuclear cells (PBMC) and Natural Killer (NK) cells. Alternatively, or additionally, ADCC activity of the molecule of interest may be assessed in vivo, e.g., in an animal model such as that disclosed in Clynes et al. PNAS (USA) 95:652-656 (1998).

[0106] “Complement dependent cytotoxicity” or “CDC” refers to the ability of a molecule to lyse a target in the presence of complement. The complement activation pathway is initiated by the binding of the first component of the complement system (Clq) to a molecule (e.g., an antibody) complexed with a cognate antigen. To assess complement activation, a CDC assay, e.g., as described in Gazzano- Santoro et al., J. Immunol. Methods 202: 163 (1996), may be performed.

[0107] “Binding affinity” refers to the strength of the sum total of noncovalent interactions between a single binding site of a molecule (e.g., an antibody) and its binding partner (e.g., an antigen). Unless indicated otherwise, as used herein, “binding affinity” refers to intrinsic binding affinity which reflects a 1: 1 interaction between members of a binding pair (e.g., antibody and antigen). The affinity of a molecule X for its partner Y can generally be represented by the dissociation constant (Kd). Affinity can be measured by common methods known in the art. Uow-affinity antibodies generally bind antigen slowly and tend to dissociate readily, whereas high-affinity antibodies generally bind antigen faster and tend to remain bound.

[0108] The term “KD” (M), “Kd,” or “Kd value,” as used herein, refers to the equilibrium dissociation constant of a particular antigen binding interaction as determined by BioUayer Interferometry, using an Octet QK384 instrument (Fortebio Inc., Menlo Park, CA) in kinetics mode. For example, anti-mouse Fc sensors are loaded with mouse-Fc fused antigen and then dipped into antibody-containing wells to measure concentration dependent association rates (kon). Antibody dissociation rates (kOfr) are measured in the final step, where the sensors are dipped into wells containing buffer only. The KD is the ratio of koff / kon. (For further details see, Concepcion, I, et al., Comb Chem High Throughput Screen, 12(8), 791-800, 2009).

[0109] In some embodiments, a molecule described herein as binding to a target antigen specifically binds to the target antigen. As used herein, a molecule (such as, e.g., an antibody, antibody fragment, or antigen-binding fragment) “specifically binds” to a target antigen when it has asignificantly higher binding affinity for, and consequently is capable of distinguishing, that antigen compared to its affinity for other unrelated proteins, under similar binding assay conditions. For example, molecules that specifically bind an antigen may bind to that antigen with an equilibrium dissociation constant (KD) < 1 X 10’6M. Molecules specifically bind antigen with “high affinity” when the KD is < 1 x 10'8M. In some embodiments, molecules described herein bind to a target antigen with a KDof < 5 x 10’7M. In some embodiments, molecules described herein bind to a target antigen with a KDof < 1 x 10’7M. In some embodiments, molecules described herein bind to a target antigen with a KDof < 5 x 10’8M. In some embodiments, molecules described herein bind to a target antigen with a KDof < 2 x 10’8M. In some embodiments, molecules described herein bind to a target antigen with a KDof < 1 x 10’8M. In some embodiments, molecules described herein bind to a target antigen with a KDof < 1 x 10’9M.

[0110] Affinity may be determined using a variety of techniques, a non-limiting example of which is an affinity ELISA assay. In some embodiments, affinity is determined by a surface plasmon resonance assay (e.g., BIAcore®-based assay). Using this methodology, the association rate constant (kain M ’s1) and the dissociation rate constant (kd in s’1) can be measured. The equilibrium dissociation constant (KD in M) can then be calculated from the ratio of the kinetic rate constants (kd / ka). In some embodiments, affinity is determined by a kinetic method, such as a Kinetic Exclusion Assay (KinExA) as described in Rathanaswami et al. Analytical Biochemistry, Vol. 373:52-60, 2008. Using a KinExA assay, the equilibrium dissociation constant (KDin M) and the association rate constant (kain M 's’1) can be measured. The dissociation rate constant (kd in s’1) can be calculated from these values (KDx ka). In other embodiments, affinity is determined by a bio-layer interferometry method, such as that described in Kumaraswamy et al., Methods Mol. Biol., Vol. 1278: 165-82, 2015 and employed in Octet® systems (Pall ForteBio). The kinetic (kaand kd) and affinity (KD) constants can be calculated in real-time using the bio-layer interferometry method.

[0111] As used herein, the term “administer” and its cognates (e.g., “administering”) includes both self-administration and administration to the subject by another person (e.g., a medical professional or caretaker).

[0112] As used herein, the term “in combination with,” in the context of administration, as well as “co-administer,” “combined administration,” and their cognates (e.g., “co-administering”), means administration of two or more therapeutic agents in a coordinated fashion to a single subject and includes, but is not limited to, concurrent administration. Specifically, “co-administration” encompasses administration of a co-formulation or simultaneous administration of separate therapeutic compositions, as well as serial or sequential administration, provided that administration of one therapeutic agent is conditioned in some way on administration of another therapeutic agent. The therapeutic agents are not necessarily administered at the same time and / or by the same route ofadministration. Illustratively, one therapeutic agent may be administered only after a different therapeutic agent has been administered and allowed to act for a prescribed period of time. Additionally, in some embodiments, co-administered therapeutic agents are present in the subject (PK), or otherwise induce an effect (PD), at similar, identical, or partially overlapping periods of time.

[0113] It is envisaged that “prior to”, in the context of a first therapeutic agent being administered prior to a second therapeutic agent, means within 72 hours, 48 hours, 36 hours, 24 hours, 18 hours, 16 hours, 12 hours, 6 hours, 5 hours, 4 hours, or 3 hours, e.g., within 120 minutes, 90 minutes, 60 minutes, or 30 minutes before the start of administration of the second therapeutic agent.

[0114] In some embodiments, the combination partners may be administered entirely separately or be entirely separate pharmaceutical dosage forms. Additionally, in some embodiments, the combination partners may be pharmaceutical compositions that are also sold independently of each other, where instructions for their combined use are provided in the package equipment, e.g., leaflet or the like, or in other information, e.g., provided to physicians and medical staff (e.g., oral communications, communications in writing, or the like).

[0115] In some embodiments, the combination partners may be brought together into a combination therapy: (i) prior to release of the combination product to physicians (e.g., in the case of a kit comprising the combination partners); (ii) by the physician themselves (or under the guidance of a physician) shortly before administration; or (iii) in the patient themselves, e.g., during sequential administration of the combination partners.

[0116] As used herein, a “combination product” refers to a pharmaceutical product that results from the mixing or combining of more than one active ingredient and includes both fixed and nonfixed combinations of the active ingredients (which may also be combined). A combination product includes a kit of components for combined administration.

[0117] As used herein, the term “non-fixed combination” refers to therapeutic agents that are administered to a patient as separate entities either simultaneously, concurrently, or sequentially with no specific time limits, wherein such administration provides therapeutically effective levels of both therapeutic agents. The latter also applies to cocktail therapy, e.g., the administration of three or more active ingredients. In a non-fixed combination, the combination partners may be dosed independently of each other or by use of different fixed combinations with distinguished amounts of the combination partners.

[0118] As used herein, the term “fixed combination” refers to at least two therapeutic agents that are both administered to a patient simultaneously in the form of a single entity or dosage (i.e., the therapeutic agents are present in one dosage form).

[0119] As used herein, the term “treatment” and its cognates (e.g., “treating”) encompass any improvement of a disease in the subject, including the slowing or stopping of the progression of a disease in the subject, a decrease in the number or severity of the symptoms of the disease, or an increase in frequency or duration of periods where the patient is free from the symptoms of the disease.

[0120] As used herein, a “therapeutically effective amount” refers to an amount of active agent that imparts a therapeutic benefit to a subject. For example, a “therapeutically effective amount” is an amount which induces, ameliorates, or otherwise causes an improvement in the pathological symptoms, disease progression, or physiological conditions associated with a disease or which improves resistance to a disorder.

[0121] The terms “subject,” “individual,” and “patient” are used interchangeably herein to refer to a mammal being assessed for treatment and / or being treated. Subjects may be human, but also include other mammals, particularly those mammals useful as laboratory models for human disease, e.g., mouse, rat, etc. In some embodiments, the mammal is a human.

[0122] The term “pharmaceutical composition” refers to a preparation which is in such form as to permit the biological activity of the active ingredient to be effective, and which contains no additional components which are unacceptably toxic to a subject to which the formulation would be administered. Such compositions are sterile. “Pharmaceutically acceptable” excipients (e.g., vehicles, additives) are those which can reasonably be administered to a subject to provide an effective dose of the active ingredient employed.

[0123] As used herein, a “sterile” composition is aseptic or free or essentially free from all living microorganisms and their spores. As used herein, a “frozen” composition is one at a temperature below 0 °C.

[0124] As used herein, a “stable” composition is one in which the protein therein essentially retains its physical stability and / or chemical stability and / or biological activity upon storage. In some embodiments, the composition essentially retains its physical and chemical stability, as well as its biological activity upon storage. The storage period is generally selected based on the intended shelflife of the composition. Various analytical techniques for measuring protein stability are available in the art and are reviewed in Peptide and Protein Drug Delivery, 247-301. Vincent Lee Ed., Marcel Dekker, Inc., New York, N.Y., Pubs. (1991) and Jones. A. Adv. Drug Delivery Rev. 10: 29-90) (1993), for example. Stability can be measured at a selected temperature for a selected time period. Stability can be evaluated qualitatively and / or quantitatively in a variety of different ways, including evaluation of aggregate formation (e.g., using size exclusion chromatography, by measuring turbidity, and / or by visual inspection); by assessing charge heterogeneity using cation exchange chromatography, image capillary isoelectric focusing (icIEF) or capillary zone electrophoresis;amino-terminal or carboxy-terminal sequence analysis; mass spectrometric analysis; SDS-PAGE analysis to compare reduced and intact antibody; peptide map (for example tryptic or LYS-C) analysis; evaluating biological activity or antigen binding function of the antibody; etc. Instability may involve any one or more of: aggregation, deamidation (e.g., Asn deamidation), oxidation (e.g., Met oxidation), isomerization (e.g., Asp isomerization), clipping / hydrolysis / fragmentation (e.g., hinge region fragmentation), succinimide formation, unpaired cysteine(s), N-terminal extension, C-terminal processing, glycosylation differences, etc.

[0125] As used herein, the term “vector” refers to a nucleic acid molecule capable of transporting another nucleic acid to which it has been linked. One type of vector is a “plasmid,” which refers to a circular double-stranded DNA loop into which additional DNA segments may be ligated. Another type of vector is a viral vector, wherein additional DNA segments may be ligated into the viral genome. Certain vectors are capable of autonomous replication in a host cell into which they are introduced (such as, e.g., bacterial vectors having a bacterial origin of replication and episomal mammalian vectors). Other vectors (such as, e.g., non-episomal mammalian vectors) may be integrated into the genome of a host cell upon introduction into the host cell, and thereby are replicated along with the host genome. Moreover, certain vectors are capable of directing the expression of genes to which they are operatively linked. Such vectors are referred to herein as “recombinant expression vectors.” In some embodiments, expression vectors for use in recombinant DNA techniques are in the form of plasmids.

[0126] As used herein, the term “host cell” refers to a cell into which an expression vector has been introduced. It should be understood that “host cell” is intended to refer not only to the particular subject cell, but also to the progeny of such a cell. Because certain modifications may occur in succeeding generations due to either mutation or environmental influences, such progeny may not, in fact, be identical to the parent cell, but are still included within the scope of the term “host cell” as used herein. Example recombinant host cells include, but are not limited to, transfectomas, such as CHO cells, HEK293 cells, NS / 0 cells, and lymphocytic cells.

[0127] As used herein, the term “autologous” refers to any material derived from an individual to whom the material is intended to be re-introduced.

[0128] As used herein, the term “allogeneic” refers to any material derived from a different animal of the same species as the individual to whom the material is introduced. Two or more individuals are said to be allogeneic to one another when the genes at one or more loci are not identical. In some embodiments, allogeneic material from individuals of the same species may be sufficiently unlike genetically to interact antigenically.

[0129] As used herein, the term “Chimeric Antigen Receptor,” or alternatively a “CAR,” refers to a recombinant polypeptide construct comprising at least an extracellular antigen binding domain, atransmembrane domain, and a cytoplasmic signaling domain (also referred to herein as “an intracellular signaling domain”) comprising a functional signaling domain derived from a stimulatory molecule. In some embodiments, the domains in the CAR polypeptide construct are in the same polypeptide chain, e.g., comprise a chimeric fusion protein. In some embodiments, the domains in the CAR polypeptide construct are not contiguous with each other, e.g., are in different polypeptide chains.

[0130] In some embodiments, the stimulatory molecule is the zeta chain associated with the T-cell receptor complex. In some embodiments, the cytoplasmic signaling domain comprises a primary signaling domain (e.g., a primary signaling domain of CD3-zeta). In some embodiments, the cytoplasmic signaling domain further comprises one or more functional signaling domains derived from at least one costimulatory molecule. In some embodiments, the costimulatory molecule is selected from 4-1BB (i.e., CD137), CD27, ICOS, and CD28. In some embodiments, the CAR comprises a chimeric fusion protein comprising an extracellular antigen binding domain, a transmembrane domain, and an intracellular signaling domain comprising a functional signaling domain derived from a stimulatory molecule. In some embodiments, the CAR comprises a chimeric fusion protein comprising an extracellular antigen binding domain, a transmembrane domain, and an intracellular signaling domain comprising a functional signaling domain derived from a costimulatory molecule and a functional signaling domain derived from a stimulatory molecule. In some embodiments, the CAR comprises a chimeric fusion protein comprising an extracellular antigen binding domain, a transmembrane domain, and an intracellular signaling domain comprising two functional signaling domains derived from one or more co-stimulatory molecule(s) and a functional signaling domain derived from a stimulatory molecule. In some embodiments, the CAR comprises a chimeric fusion protein comprising an extracellular antigen binding domain, a transmembrane domain, and an intracellular signaling domain comprising at least two functional signaling domains derived from one or more co-stimulatory molecule(s) and a functional signaling domain derived from a stimulatory molecule. In some embodiments, the CAR comprises an optional leader sequence at the amino-terminus (N-term) of the CAR fusion protein. In some embodiments, the CAR further comprises a leader sequence at the N-terminus of the extracellular antigen binding domain, wherein the leader sequence is optionally cleaved from the antigen recognition domain (e.g., a scFv) during cellular processing and localization of the CAR to the cellular membrane.

[0131] As used herein, the term “signaling domain” refers to the functional portion of a protein which acts by transmitting information within the cell to regulate cellular activity via defined signaling pathways by generating second messengers or functioning as effectors by responding to such messengers. In some embodiments, the signaling domain of a CAR described herein is derived from a stimulatory molecule or co-stimulatory molecule, or is a synthesized or engineered signaling domain.

[0132] As used herein, an “intracellular signaling domain” refers to an intracellular portion of a molecule. The intracellular signaling domain generates a signal that promotes an immune effector function of the CAR-expressing cell, e.g., a CAR-T cell or CAR-expressing NK cell. Non-limiting examples of immune effector function, e.g., in a CAR-T cell or CAR-expressing NK cell, include cytolytic activity and helper activity, including the secretion of cytokines. While the entire intracellular signaling domain can be employed, in many cases it is not necessary to use the entire chain. To the extent that a truncated portion of the intracellular signaling domain is used, such truncated portion may be used in place of the intact chain as long as it transduces the effector function signal. The term intracellular signaling domain is thus meant to include any truncated portion of the intracellular signaling domain sufficient to transduce the effector function signal.

[0133] In some embodiments, the intracellular signaling domain may comprise a primary intracellular signaling domain. Example primary intracellular signaling domains include, but are not limited to, those derived from the molecules responsible for primary stimulation, or antigen dependent stimulation. In some embodiments, the intracellular signaling domain comprises a costimulatory intracellular domain. Example costimulatory intracellular signaling domains include, but are not limited to, those derived from molecules responsible for costimulatory signals, or antigen independent stimulation. In some embodiments, the intracellular signaling domain is synthesized or engineered. For example, in the case of a CAR-expressing immune effector cell, e.g., CAR-T cell or CAR- expressing NK cell, a primary intracellular signaling domain may comprise a cytoplasmic sequence of a T cell receptor, a primary intracellular signaling domain may comprise a cytoplasmic sequence of a T cell receptor, and a costimulatory intracellular signaling domain may comprise cytoplasmic sequence from co-receptor or costimulatory molecule.

[0134] In some embodiments, a primary intracellular signaling domain comprises a signaling motif which is known as an immunoreceptor tyrosine-based activation motif or ITAM. Examples of ITAM containing primary cytoplasmic signaling sequences include, but are not limited to, those derived from CD3 zeta, common FcR gamma (FCER1G), Fc gamma Rlla, FcR beta, CD3 gamma, CD3 delta, CD3 epsilon, CDS, CD22, CD79a, CD79b, CD278 (“ICOS”), FcsRI CD66d, DAP10, and DAP12.

[0135] As used herein, the term “costimulatory molecule” refers to the cognate binding partner on a T cell that binds with a costimulatory ligand, thereby mediating a costimulatory response by the T cell, including, but not limited to, proliferation. Costimulatory molecules are cell surface molecules other than antigen receptors or their ligands that are required for an efficient immune response. Costimulatory molecules include, but are not limited to, an MHC class I molecule, a TNF receptor protein, an Immunoglobulin-like protein, a cytokine receptor, an integrin, a signaling lymphocytic activation molecule (SLAM protein), an activating NK cell receptor, BTLA, a Toll ligand receptor, 0X40, CD2, CD7, CD27, CD28, CD30, CD40, CDS, ICAM-1, LFA-1 (CD1 la / CD18), 4-1BB(CD137), B7-H3, CDS, ICAM-1, ICOS (CD278), GITR, BAFFR, LIGHT, HVEM (LIGHTR), KIRDS2, SLAMF7, NKp80 (KLRF1), NKp44, NKp30, NKp46, CD19, CD4, CD8alpha, CD8beta, IL2R beta, IL2R gamma, IL7R alpha, ITGA4, VLA1, CD49a, ITGA4, IA4, CD49D, ITGA6, VLA-6, CD49f, ITGAD, CDl ld, ITGAE, CD103, ITGAL, CDl la, LFA-1, ITGAM, CDl lb, ITGAX, CDl lc, ITGB1, CD29, ITGB2, CD 18, LFA-1, ITGB7, NKG2D, NKG2C, TNFR2, TRANCE / RANKL, DNAM1 (CD226), SLAMF4 (CD244, 2B4), CD84, CD96 (Tactile), CEACAM1, CRTAM, Ly9 (CD229), CD160 (BY55), PSGL1, CD100 (SEMA4D), CD69, SLAMF6 (NTB-A, Lyl08), SLAM (SLAMF1, CD 150, IPO-3), BLAME (SLAMF8), SELPLG (CD 162), LTBR, LAT, GADS, SLP-76, PAG / Cbp, CD 19a, and a ligand that binds with CD83.

[0136] In some embodiments, a costimulatory intracellular signaling domain can be the intracellular portion of a costimulatory molecule. The intracellular signaling domain can comprise the entire intracellular portion, or the entire native intracellular signaling domain, of the molecule from which it is derived, or a functional fragment thereof.

[0137] As used herein, the term “zeta,” or alternatively “zeta chain” or “CD3-zeta,” is defined as the protein provided as GenBank Acc. No. BAG36664. 1, or the equivalent residues from a non-human species, e.g., mouse, rodent, monkey, ape, and the like, and a “zeta stimulatory domain,” or alternatively a “CD3-zeta stimulatory domain,” is defined as the amino acid residues from the cytoplasmic domain of the zeta chain that are sufficient to functionally transmit an initial signal necessary for T cell activation. In some embodiments, the cytoplasmic domain of zeta comprises residues 52 through 164 of GenBank Acc. No. BAG36664.1 or the equivalent residues from a non- human species, e.g., mouse, rodent, monkey, ape and the like, which are functional orthologs thereof.

[0138] As used herein, the term “4- IBB” refers to a member of the TNFR superfamily with an amino acid sequence provided as GenBank Acc. No. AAA62478.2, or the equivalent residues from a non-human species, e.g., mouse, rodent, monkey, ape and the like; and a “4-1BB costimulatory domain” is defined as amino acid residues 214-255 of GenBank Acc. No. AAA62478.2, or the equivalent residues from a non-human species, e.g., mouse, rodent, monkey, ape and the like.

[0139] As used herein, the term “T-cell redirecting therapy” refers to a therapeutic agent, such as a T-cell engaging molecule or a CAR T-cell, capable of recruiting T-cells to a target cell or tissue.

[0140] As used herein, the term “T-cell engaging molecule” refers to a molecule that comprises at least one domain in which the structure is derived from or comprises the minimum structural features of an antibody, e.g., of a full-length immunoglobulin molecule, that allow for specific binding to an antigen on the surface of a T cell, such as CD3. Thus, a T-cell engaging molecule according to the present disclosure generally comprises one or more binding domains, each of which will typically comprise the minimum structural requirements of an antibody that allow for specific target binding. This minimum requirement may, for example, be defined by the presence of at least three light chain“complementarity determining regions” or CDRs (i.e., CDRL1, CDRL2 and CDRL3 of a VL region) and / or three heavy chain CDRs (i.e., CDRH1, CDRH2 and CDRH3 of a VH region), such as, e.g., all six CDRs from both the light and heavy chain variable regions. The T-cell engaging molecules according to the present disclosure may comprise domains or regions (e.g., CDRs or variable regions) from monoclonal, chimeric, humanized and human antibodies. In some embodiments, the T-cell engaging molecules used in the methods of the present disclosure are proteins and comprise one or more polypeptide chains. In some embodiments, the T-cell engaging molecules administered according to the methods of the present disclosure are single-chain polypeptides. In other embodiments, the T-cell engaging molecules administered according to the methods of the present disclosure comprise two or more polypeptide chains - e.g., are polypeptide dimers or multimers. In certain embodiments, the T-cell engaging molecules administered according to the methods of the present disclosure comprise four polypeptide chains, and may, e.g., have the format of an antibody or an immunoglobulin protein.

[0141] As used herein, the term “bispecific T-cell engaging molecule” refers to a molecule capable of specifically binding to two different antigens. In the context of the present disclosure, bispecific T- cell engaging molecules specifically bind to a cancer cell antigen (e.g., human cancer cell antigen) on the cell surface of target cells and CD3 (e.g., human CD3) on the cell surface of T cells. In some embodiments, the T-cell engaging molecules may bind to more than one cancer cell antigen (e.g., human cancer cell antigen) on the cell surface of target cells as well as to CD3 (e.g., human CD3) on the cell surface of T cells. Thus, in such embodiments, the T-cell engaging molecules are “multitargeting” in that they are capable of specifically binding to two or more different cancer cell antigens and redirecting T cells to more than one type of cancer cell or cancer cells expressing the two or more antigens.

[0142] In some embodiments, the T-cell engaging molecules or binding domains thereof used in the methods of the disclosure bind to that antigen with an equilibrium dissociation constant (KD) < 1 x 10'6M. In one embodiment, the T-cell engaging molecules or binding domains thereof used in the methods of the present disclosure bind to a human cancer cell antigen and / or human CD3 with a KD of < 5 x 10'7M. In another embodiment, the T-cell engaging molecules or binding domains thereof used in the methods of the present disclosure bind to a human cancer cell antigen and / or human CD3 with a KDof < 1 x 10'7M. In yet another embodiment, the T-cell engaging molecules or binding domains thereof used in the methods of the present disclosure bind to a human cancer cell antigen and / or human CD3 with a KD of < 5 x 10'8M. In another embodiment, the T-cell engaging molecules or binding domains thereof used in the methods of the present disclosure bind to a human cancer cell antigen and / or human CD3 with a KD of < 2 x 10'8M. In certain embodiments, the T-cell engaging molecules or binding domains thereof used in the methods of the present disclosure bind to a human cancer cell antigen and / or human CD3 with a KDof < 1 x 10'8M. In other embodiments, the T-cellengaging molecules or binding domains thereof used in the methods of the present disclosure bind to a human cancer cell antigen and / or human CD3 with a KDof < 1 x IO9M.

[0143] In some embodiments, the T-cell engaging molecules or binding domains thereof described herein exhibit desirable characteristics such as binding avidity as measured by kd (dissociation rate constant) for a human cancer cell antigen and / or human CD3 of 10'2, 10'3, 10'4, 10'5, 10'6, 10'7, 10'8, 10'9, IO-10s1or lower (lower values indicating higher binding avidity), and / or binding affinity as measured by KD (equilibrium dissociation constant) for a human cancer cell antigen and / or human CD3 of 10'7, 10'8, 10'9, IO-10, 10'11M or lower (lower values indicating higher binding affinity).

[0144] In some embodiments, bispecific T-cell engaging molecules used in the methods of the present disclosure may be antibodies and have the general structure of a full-length immunoglobulin. For example, the bispecific T-cell engaging molecules may comprise two full-length antibody heavy chains and two full-length antibody light chains. In particular embodiments, the bispecific T-cell engaging molecules are heterodimeric antibodies (used interchangeably herein with “hetero immunoglobulins” or “hetero Igs”), which refer to antibodies comprising two different light chains and two different heavy chains. For instance, in some embodiments, the heterodimeric antibody comprises a light chain and heavy chain from an antibody that binds to a cancer cell antigen, such as the cancer cell antigens described further herein, and a light chain and heavy chain from an antibody that binds to CD3.

[0145] The bispecific T-cell engaging molecules employed in the methods of the present disclosure may also comprise fragments of full-length antibodies, such as VH, VHH, VL, (s)dAb, Fv, light chain (VL-CL), Fd (VH-CH1), heavy chain, Fab, Fab’, F(ab')2 or “r IgG” (“half antibody” consisting of a heavy chain and a light chain). Bispecific T-cell engaging molecules according to the present disclosure may also comprise modified fragments of antibodies. Examples of such modified fragments include, but are not limited to, single-chain variable fragment (scFv), di-scFv or bi(s)-scFv, scFv-Fc, scFv-zipper, single-chain Fab (scFab), Fab2, Fab;, diabodies, single-chain diabodies, tandem diabodies (Tandabs), tandem di-scFv, tandem tri-scFv, “minibodies” exemplified by a structure which is as follows: (VH-VL-CH3)2, (scFv-CH3)2, ((scFv)2-CH3 + CH3), ((scFv)2-CH3) or (scFv-CH3- SCFV)2, multibodies, such as triabodies or tetrabodies, and single domain antibodies, such as nanobodies or single variable domain antibodies comprising merely one variable region, which might be VHH, VH or VL, that binds to an antigen or target independently of other variable regions or domains.

[0146] In some embodiments, the bispecific T-cell engaging molecule is a three-chain antibodylike molecule. In some embodiments, the bispecific T-cell engaging molecule is a heterodimeric IgG molecule (hetero-IgG). In some embodiments, the bispecific T-cell engaging molecule is a half-life extended (HLE) BiTE® molecule.

[0147] In certain embodiments, the bispecific T-cell engaging molecules used in the methods of the present disclosure are multivalent. The valency of the T-cell engaging molecule denotes the number of individual antigen-binding domains within the T-cell engaging molecule. For example, the terms “monovalent,” “bivalent,” and “tetravalent,” with reference to the T-cell engaging molecules in the context of the present disclosure, refer to T-cell engaging molecules with one, two, and four antigenbinding domains, respectively. Thus, a multivalent T-cell engaging molecule comprises two or more antigen-binding domains. A T-cell engaging molecule can have more antigen-binding domains (e.g., a higher valency) than specificities. For example, a T-cell engaging molecule having two antigenbinding domains for a first target (e.g., cancer cell antigen) and one antigen-binding domain for a second target (CD3) - or vice versa - is considered to be trivalent (three antigen-binding domains) and bispecific (binds to two antigens). In certain embodiments, the bispecific T-cell engaging molecules used in the methods of the present disclosure are bivalent. Thus, such bispecific, bivalent T-cell engaging molecules contain two antigen binding domains: one antigen-binding domain for a cancer cell antigen (e.g., a human cancer cell antigen) and one antigen-binding domain for CD3 (e.g., human CD3). In other embodiments, the T-cell engaging molecules used in the methods of the present disclosure are trivalent, trispecific T-cell engaging molecules and comprise three antigen binding domains: one antigen binding domain for a first cancer cell antigen, another antigen binding domain for a second cancer cell antigen, and a third binding domain for CD3. In still other embodiments, the T-cell engaging molecules used in the methods of the present disclosure are tetravalent, trispecific T- cell engaging molecules and comprise four antigen binding domains: one antigen binding domain for a first cancer cell antigen, another antigen binding domain for a second cancer cell antigen, and two antigen binding domains for CD3.

[0148] In some embodiments, the bispecific T-cell engaging molecules employed in the methods of the present disclosure comprise a first binding domain that binds to a target cancer cell antigen (e.g., a human target cancer cell antigen) and a second binding domain that binds to CD3 (e.g., human CD3). As used herein, the term “antigen-binding domain,” which is used interchangeably with “binding domain,” refers to the region of the T-cell engaging molecule that contains the amino acid residues that interact with the antigen and confer on the T-cell engaging molecule its specificity and affinity for the antigen. In certain embodiments, one or more binding domains of the T-cell engaging molecules may be derived from an antibody or antigen-binding fragment thereof. For instance, the binding domains of the bispecific T-cell engaging molecules used in the methods of the present disclosure may comprise one or more CDRs from the light and heavy chain variable regions of antibodies that specifically bind to a human target cancer cell antigen and / or human CD3. In some embodiments, the anti-cancer cell antigen binding domain of the bispecific T-cell engaging molecules comprises all six CDRs of the heavy and light chain variable regions of an antibody that binds to that human target cancer cell antigen and the anti-CD3 binding domain of the bispecific T-cell engagingmolecules comprises all six CDRs of the heavy and light chain variable regions of an anti-CD3 antibody. In some embodiments, the binding domains (the anti-cancer cell antigen binding domain, the anti-CD3 binding domain or both) of the bispecific T-cell engaging molecules used in the methods of the present disclosure comprise a Fab, a Fab', a F(ab')2, a Fv, a single-chain variable fragment (scFv), or a nanobody. In one embodiment, both binding domains of the bispecific T-cell engaging molecule are Fab fragments. In another embodiment, one binding domain of the bispecific T-cell engaging molecule is a Fab fragment and the other binding domain is a scFv. In yet another embodiment, both binding domains of the bispecific T-cell engaging molecule are scFvs.ANTI-IL-2RBG HEAVY-CHAIN ANTIBODIES

[0149] Provided herein is a heavy-chain antibody (e.g., an anti-IL2RBG heavy-chain antibody) comprising an Fc region that comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, and a cysteine at position 302, all according to EU numbering. For example, provided herein is a heavy-chain antibody comprising a first heavy chain variable (VH) region that binds to IL2RB, a second heavy chain variable region that binds to IL2RG, and an Fc region that comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, and a cysteine at position 302, all according to EU numbering.

[0150] Also provided herein is a heavy-chain antibody (e.g., an anti-IL2RBG heavy-chain antibody) comprising a first heavy chain variable region, a second heavy chain variable region, and an Fc region, wherein the first heavy chain variable region is connected to the Fc region by a first peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids, and the second heavy chain variable region is connected to the Fc region by a second peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids. For example, provided herein is a heavy-chain antibody comprising a first heavy chain variable (VH) region that binds to IL2RB, a second heavy chain variable region that binds to IL2RG, and an Fc region, wherein the first heavy chain variable region is connected to the Fc region by a first peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids, and the second heavy chain variable region is connected to the Fc region by a second peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids.

[0151] In some embodiments, the VH region that binds to IL2RB or IL2RG was described in WO 2022 / 212848, which is incorporated by reference herein. For example, in some embodiments, the first VH region that binds to IL2RB comprises CDR sequences having the following amino acid sequences as defined by IMGT. Heavy-chain antibodies comprising these CDR sequences can be referred to herein as IL2RB F09 antibodies. An “X” indicates a variable amino acid, which may, in some embodiments, be a specific amino acid listed below:CDR1 (IL2RB F09)GGSISSSXiW (SEQ ID NO: 26) wherein Xi is D or N;CDR2 (IL2RB F09)I X2H S G S T (SEQ ID NO: 27) wherein X2is D or S; andCDR3 (IL2RB F09)X3RGX4WELX5DAFDI (SEQ ID NO: 28) wherein X3 is G or A; X4 is S or Q; and X5 is S or T.

[0152] In other embodiments, the first VH region that binds to IL2RB comprises CDR sequences having the following amino acid sequences as defined by IMGT. Heavy-chain antibodies comprising these CDR sequences can be referred to herein as IL2RB F18 antibodies. An “X” indicates a variable amino acid, which may, in some embodiments, be a specific amino acid listed below:CDR1 (IL2RB F18)GFTFSXiYG (SEQ ID NO: 29) wherein Xi is S or T;CDR2 (IL2RB F18)I S Y D G S N X2(SEQ ID NO: 30) wherein X2is K or R; andCDR3 (IL2RB F18)A RD E D Y D X3 L T GD P V GG F D I (SEQ ID NO: 31) wherein X3 is V or I.

[0153] In some embodiments, the first VH region that binds to IL2RB comprises the VH CDR1, CDR2, and CDR3 sequences set forth in TABLE 2. The specific CDRs identified in TABLE 2 are defined by IMGT. In some embodiments, the first VH region that binds to IL2RB comprises a heavy chain variable region (VH) sequence set forth in TABLE 3.TABLE 2. Anti-IL2RB Heavy-Chain Antibody Unique CDR Amino Acid Sequences (IMGT)TABLE 3. Anti-IL2RB Heavy-Chain Antibody Variable Region Amino Acid Sequences

[0154] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to any one of SEQ ID NOs: 1-3; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to any one of SEQ ID NOs: 4-6; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to any one of SEQ ID NOs: 7-10. In some embodiments, thefirst VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 1 or SEQ ID NO: 2; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 4 or SEQ ID NO: 5; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 7, SEQ ID NO: 8, or SEQ ID NO: 9.

[0155] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 1; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 4; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 7.

[0156] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 1; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 4; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 8.

[0157] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 2; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 5; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 9.

[0158] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 3; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 6; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 10.

[0159] In some embodiments, each amino acid modification, if any, is an amino acid substitution, an amino acid addition, or an amino acid deletion. In some embodiments, each amino acid modification, if any, is an amino acid substitution. In some embodiments, each amino acid modification, if any, is a conservative amino acid substitution.

[0160] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to any one of SEQ ID NOs: 1-3; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to any one of SEQ ID NOs: 4-6; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to any one of SEQ ID NOs: 7-10. In some embodiments, the firstVH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 1 or SEQ ID NO: 2; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 4 or SEQ ID NO: 5; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 7, SEQ ID NO: 8, or SEQ ID NO: 9.

[0161] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 1; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 4; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 7.

[0162] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 1; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 4; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 8.

[0163] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 2; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 5; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 9.

[0164] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 3; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 6; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 10.

[0165] In some embodiments, the at most one amino acid modification is an amino acid substitution. In some embodiments, the at most one amino acid modification is a conservative amino acid substitution. In some embodiments, the at most one amino acid modification is an amino acid deletion. In some embodiments, the at most one amino acid modification is an amino acid addition. In some embodiments, each amino acid modification, if any, is an amino acid substitution. In some embodiments, each amino acid modification, if any, is a conservative amino acid substitution.

[0166] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 1 or SEQ ID NO: 2; SEQ ID NO: 4 or SEQ ID NO: 5; and SEQ ID NO: 7, SEQ ID NO: 8, or SEQ ID NO: 9, respectively. In otherembodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 3, SEQ ID NO: 6, and SEQ ID NO: 10, respectively.

[0167] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of:(a) SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 7, respectively; or(b) SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 8, respectively; or(c) SEQ ID NO: 2, SEQ ID NO: 5, and SEQ ID NO: 9, respectively; or(d) SEQ ID NO: 3, SEQ ID NO: 6, and SEQ ID NO: 10, respectively.

[0168] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of:(a) SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 7, respectively; or(b) SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 8, respectively; or(c) SEQ ID NO: 2, SEQ ID NO: 5, and SEQ ID NO: 9, respectively.

[0169] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 7, respectively.

[0170] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 8, respectively.

[0171] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 2, SEQ ID NO: 5, and SEQ ID NO: 9, respectively.

[0172] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 3, SEQ ID NO: 6, and SEQ ID NO: 10, respectively.

[0173] In some embodiments, the first VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to any one of SEQ ID NOs: 11-14. In some embodiments, the first VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to any one of SEQ ID NOs: 11-13.

[0174] In some embodiments, the first VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the amino acid sequence of SEQ ID NO: 11. In some embodiments, the first VH region comprises an amino acidsequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the amino acid sequence of SEQ ID NO: 12. In some embodiments, the first VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the amino acid sequence of SEQ ID NO: 13. In some embodiments, the first VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the amino acid sequence of SEQ ID NO: 14.

[0175] In some embodiments, the first VH region comprises an amino acid sequence selected from SEQ ID NOs: 11-14. In some embodiments, the first VH region comprises an amino acid sequence selected from SEQ ID NOs: 11-13.

[0176] In some embodiments, the first VH region comprises the amino acid sequence of SEQ ID NO: 11. In some embodiments, the first VH region comprises the amino acid sequence of SEQ IDNO: 12. In some embodiments, the first VH region comprises the amino acid sequence of SEQ IDNO: 13. In some embodiments, the first VH region comprises the amino acid sequence of SEQ IDNO: 14.

[0177] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-13.

[0178] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 14.

[0179] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2,and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-13, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT.

[0180] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 14, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT.

[0181] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-13, wherein the VH CDRs 1, 2, and 3 are defined by Kabat.

[0182] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 14, wherein the VH CDRs 1, 2, and 3 are defined by Kabat.

[0183] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-13, wherein the VH CDRs 1, 2, and 3 are defined by Chothia.

[0184] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 14, wherein the VH CDRs 1, 2, and 3 are defined by Chothia.

[0185] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14, wherein the VH CDRs 1, 2, and 3 are defined by IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-13, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0186] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11, wherein the VH CDRs 1, 2, and 3 are defined by IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12, wherein the VH CDRs 1, 2, and 3 are defined by IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13, wherein the VH CDRs 1, 2, and 3 are defined by IMGT. In someembodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 14, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0187] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-13.

[0188] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 14.

[0189] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-13, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT.

[0190] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 14, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT.

[0191] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-13, wherein the VH CDRs 1, 2, and 3 are defined by Kabat.

[0192] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 14, wherein the VH CDRs 1, 2, and 3 are defined by Kabat.

[0193] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-13, wherein the VH CDRs 1, 2, and 3 are defined by Chothia.

[0194] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 14, wherein the VH CDRs 1, 2, and 3 are defined by Chothia.

[0195] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-14, wherein the VH CDRs 1, 2, and 3 are defined by IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 11-13, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0196] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11, wherein the VH CDRs 1, 2, and 3 are defined by IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12, wherein the VH CDRs 1, 2, and 3 are defined by IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13, wherein the VH CDRs 1, 2, and 3 are defined by IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3(combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 14, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0197] In some embodiments, the second VH region that binds to IL2RG comprises CDR sequences having the following amino acid sequences as defined by IMGT. Heavy-chain antibodies comprising these CDR sequences can be referred to herein as IL2RG F16 antibodies. An “X” indicates a variable amino acid, which may, in some embodiments, be a specific amino acid listed below:CDR1 (IL2RG F16)G F Xi X2X3X4Y Y (SEQ ID NO: 32) wherein Xi is T or I; X2is F or V; X3is S, N, or G; and X4is D or N;CDR2 (IL2RG F16)I S X5S G X6X71 (SEQ ID NO: 33) wherein X is S or N; Xe is D, S, G, or N; and X7is T or I; andCDR3 (IL2RG F16)ARGDAVSITGDY (SEQ ID NO: 20).

[0198] In other embodiments, the second VH region that binds to IL2RG comprises a VH CDR1 sequence comprising GFTFSDYY (SEQ ID NO: 15), a VH CDR2 (IL2RG F18) sequence comprising ISSSGTTT (SEQ ID NO: 19), and a VH CDR3 (IL2RG F18) sequence comprising ARGAAVAPGFDS (SEQ ID NO: 21). Heavy-chain antibodies of comprising these CDR sequences can be referred to herein as IL2RG F18 antibodies.

[0199] In some embodiments, the second VH region that binds to IL2RG comprises the VH CDR1, CDR2, and CDR3 sequences set forth in TABLE 4. The specific CDRs identified in TABLE 4 are defined by IMGT. In some embodiments, the second VH region that binds to IL2RG comprises a heavy chain variable region (VH) sequence set forth in TABLE 5.TABLE 4. Anti-IL2RG Heavy-Chain Antibody CDR1, CDR2 and CDR3 Amino Acid SequencesTABLE 5. Anti-IL2RG Heavy-Chain Antibody Variable Region Amino Acid Sequences

[0200] In some embodiments, the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 15 or SEQ ID NO: 16; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to any one of SEQ ID NOs: 17-19; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 20 or SEQ ID NO: 21.

[0201] In some embodiments, the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 15 or SEQ ID NO: 16; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 17 or SEQ ID NO: 18; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 20.

[0202] In some embodiments, the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 15; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 17; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 20.

[0203] In some embodiments, the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 15; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 18; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 20.

[0204] In some embodiments, the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 16; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 18; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 20.

[0205] In some embodiments, the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 15; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 19; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 21.

[0206] In some embodiments, each amino acid modification, if any, is an amino acid substitution, an amino acid addition, or an amino acid deletion. In some embodiments, each amino acid modification, if any, is an amino acid substitution. In some embodiments, each amino acid modification, if any, is a conservative amino acid substitution.

[0207] In some embodiments, the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 15 or SEQ ID NO: 16; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to any one of SEQ ID NOs: 17-19; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 20 or SEQ ID NO: 21.

[0208] In some embodiments, the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 15 or SEQ ID NO: 16; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 17 or SEQ ID NO: 18; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 20.

[0209] In some embodiments, the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 15; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 17; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 20.

[0210] In some embodiments, the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 15; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 18; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 20.

[0211] In some embodiments, the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 16; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 18; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 20.

[0212] In some embodiments, the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 15; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 19; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 21.

[0213] In some embodiments, the at most one amino acid modification is an amino acid substitution. In some embodiments, the at most one amino acid modification is a conservative amino acid substitution. In some embodiments, the at most one amino acid modification is an amino acid deletion. In some embodiments, the at most one amino acid modification is an amino acid addition. In some embodiments, each amino acid modification, if any, is an amino acid substitution. In some embodiments, each amino acid modification, if any, is a conservative amino acid substitution.

[0214] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15 or SEQ ID NO: 16; SEQ ID NO: 17 or SEQ ID NO: 18; and SEQ ID NO: 20, respectively. In other embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 19, and SEQ ID NO: 21, respectively.

[0215] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of:(a) SEQ ID NO: 15, SEQ ID NO: 17, and SEQ ID NO: 20, respectively; or(b) SEQ ID NO: 15, SEQ ID NO: 18, and SEQ ID NO: 20, respectively; or(c) SEQ ID NO: 16, SEQ ID NO: 18, and SEQ ID NO: 20, respectively; or(d) SEQ ID NO: 15, SEQ ID NO: 19, and SEQ ID NO: 21, respectively.

[0216] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of:(a) SEQ ID NO: 15, SEQ ID NO: 17, and SEQ ID NO: 20, respectively; or(b) SEQ ID NO: 15, SEQ ID NO: 18, and SEQ ID NO: 20, respectively; or(c) SEQ ID NO: 16, SEQ ID NO: 18, and SEQ ID NO: 20, respectively.

[0217] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 17, and SEQ ID NO: 20, respectively.

[0218] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 18, and SEQ ID NO: 20, respectively.

[0219] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 16, SEQ ID NO: 18, and SEQ ID NO: 20, respectively.

[0220] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 19, and SEQ ID NO: 21, respectively.

[0221] In some embodiments, the second VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to any one of SEQ ID NOs: 22-25. In some embodiments, the second VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to any one of SEQ ID NOs: 22-24.

[0222] In some embodiments, the second VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 22. In some embodiments, the second VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 23. In some embodiments, the second VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 24. In some embodiments, the second VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 25.

[0223] In some embodiments, the second VH region comprises an amino acid sequence selected from SEQ ID NOs: 22-25. In some embodiments, the second VH region comprises an amino acid sequence selected from SEQ ID NOs: 22-24.

[0224] In some embodiments, the second VH region comprises the amino acid sequence of SEQ ID NO: 22. In some embodiments, the second VH region comprises the amino acid sequence of SEQID NO: 23. In some embodiments, the second VH region comprises the amino acid sequence of SEQ ID NO: 24. In some embodiments, the second VH region comprises the amino acid sequence of SEQ ID NO: 25.

[0225] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-24.

[0226] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25.

[0227] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-24, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT.

[0228] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ IDNO: 24, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT.

[0229] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-24, wherein the VH CDRs 1, 2, and 3 are defined by Kabat.

[0230] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25, wherein the VH CDRs 1, 2, and 3 are defined by Kabat.

[0231] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-24, wherein the VH CDRs 1, 2, and 3 are defined by Chothia.

[0232] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22, wherein the VH CDRs 1, 2, and 3 are defined byChothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25, wherein the VH CDRs 1, 2, and 3 are defined by Chothia.

[0233] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25, wherein the VH CDRs 1, 2, and 3 are defined by IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-24, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0234] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22, wherein the VH CDRs 1, 2, and 3 are defined by IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24, wherein the VH CDRs 1, 2, and 3 are defined by IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0235] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-24.

[0236] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25.

[0237] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-24, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT.

[0238] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT.

[0239] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-24, wherein the VH CDRs 1, 2, and 3 are defined by Kabat.

[0240] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VHCDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25, wherein the VH CDRs 1, 2, and 3 are defined by Kabat.

[0241] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-24, wherein the VH CDRs 1, 2, and 3 are defined by Chothia.

[0242] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25, wherein the VH CDRs 1, 2, and 3 are defined by Chothia.

[0243] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-25, wherein the VH CDRs 1, 2, and 3 are defined by IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of any one of SEQ ID NOs: 22-24, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0244] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22, wherein the VH CDRs 1, 2, and 3 are defined by IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24, wherein the VH CDRs 1, 2, and 3 are defined by IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0245] IL2RB F09, IL2RB F18, IL2RG F16, and IL2RG F18 antibodies are cross-reactive with the IL2R protein of Cynomolgus macaque, which facilitates the use of Cynomolgus macaque as an animal model for validating, e.g., mechanism of action, pharmacokinetics, toxicology, and other attributes of the heavy chain-only antibodies and antigen-binding fragments described herein.

[0246] In some embodiments, the VH CDR sequences of the first VH region or the second VH region may be situated, as an example, in the region of around amino acid residues 26-33; 51-58; and 97-116 for VH CDR1, VH CDR2, and VH CDR3, respectively, of the provided example variable region sequences set forth in SEQ ID NOs: 11-14 and 22-25. It will be understood by one of ordinary skill in the art that the CDR sequences may be in different positions if a different framework sequence is selected, although generally the order of the sequences will remain the same.

[0247] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 26, SEQ ID NO: Tl, and SEQ ID NO: 28, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 32, SEQ ID NO: 33, and SEQ ID NO: 20, respectively.

[0248] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 26, SEQ ID NO: Tl, and SEQ ID NO: 28, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 19, and SEQ ID NO: 21, respectively.

[0249] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 29, SEQ ID NO: 30, and SEQ ID NO: 31, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 32, SEQ ID NO: 33, and SEQ ID NO: 20, respectively.

[0250] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 29, SEQ ID NO: 30, and SEQ ID NO: 31, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 19, and SEQ ID NO: 21, respectively.

[0251] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to any one of SEQ ID NOs: 1-3; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to any one of SEQ ID NOs: 4-6; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to any one of SEQ ID NOs: 7-10; and the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 15 or SEQ ID NO: 16; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to any one of SEQ ID NOs: 17-19; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 20 or SEQ ID NO: 21.

[0252] In some embodiments, each amino acid modification, if any, is an amino acid substitution, an amino acid addition, or an amino acid deletion. In some embodiments, each amino acidmodification, if any, is an amino acid substitution. In some embodiments, each amino acid modification, if any, is a conservative amino acid substitution.

[0253] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to any one of SEQ ID NOs: 1-3; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to any one of SEQ ID NOs: 4-6; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to any one of SEQ ID NOs: 7-10; and the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 15 or SEQ ID NO: 16; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to any one of SEQ ID NOs: 17-19; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 20 or SEQ ID NO: 21.

[0254] In some embodiments, the at most one amino acid modification is an amino acid substitution. In some embodiments, the at most one amino acid modification is a conservative amino acid substitution. In some embodiments, the at most one amino acid modification is an amino acid deletion. In some embodiments, the at most one amino acid modification is an amino acid addition. In some embodiments, each amino acid modification, if any, is an amino acid substitution. In some embodiments, each amino acid modification, if any, is a conservative amino acid substitution.

[0255] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 1; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 4; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 8; and the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 15; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 17; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 20.

[0256] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 1; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 4; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 7; and the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 15; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative toSEQ ID NO: 17; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 20.

[0257] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 7, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 17, and SEQ ID NO: 20, respectively.

[0258] In some embodiments, the first VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 11, and the second VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 22. In some embodiments, the first VH region comprises the amino acid sequence of SEQ ID NO: 11, and the second VH region comprises the amino acid sequence of SEQ ID NO: 22.

[0259] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11; and the full set of VHCDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0260] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22, wherein the VH CDRs1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1,2, and 3 of SEQ ID NO: 22, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 11; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 22, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0261] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 1; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 4; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 8; and the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 15; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 18; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 20.

[0262] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 1; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 4; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 8; and the second VH region comprises a VH CDR1 comprisingan amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 15; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 18; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 20.

[0263] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 1; SEQ ID NO: 4, and SEQ ID NO: 8, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 18, and SEQ ID NO: 20, respectively.

[0264] In some embodiments, the first VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 12, and the second VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 23. In some embodiments, the first VH region comprises the amino acid sequence of SEQ ID NO: 12, and the second VH region comprises the amino acid sequence of SEQ ID NO: 23.

[0265] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3(combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0266] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1,2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0267] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 2; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 5; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 9; and the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 15; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 18; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 20.

[0268] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 2; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ IDNO: 5; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 9; and the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 15; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 18; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 20.

[0269] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 2, SEQ ID NO: 5, and SEQ ID NO: 9, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 18, and SEQ ID NO: 20, respectively.

[0270] In some embodiments, the first VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 13, and the second VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 23. In some embodiments, the first VH region comprises the amino acid sequence of SEQ ID NO: 13, and the second VH region comprises the amino acid sequence of SEQ ID NO: 23.

[0271] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%;80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0272] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1,2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0273] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 1; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 4; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 8; and the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 16; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 18; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 20.

[0274] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 1; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 4; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 8; and the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 16; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 18; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 20.

[0275] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 8, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 16, SEQ ID NO: 18, and SEQ ID NO: 20, respectively.

[0276] In some embodiments, the first VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 12, and the second VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 24. In some embodiments, the first VH region comprises the amino acid sequence of SEQ ID NO: 12, and the second VH region comprises the amino acid sequence of SEQ ID NO: 24.

[0277] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the firstVH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0278] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24, wherein the VH CDRs1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1,2, and 3 of SEQ ID NO: 24, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 24, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0279] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 1; a VH CDR2 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 4; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 8; and the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 15; a VH CDR2 comprising an amino acid sequence having at most two amino acidmodifications relative to SEQ ID NO: 19; and a VH CDR3 comprising an amino acid sequence having at most two amino acid modifications relative to SEQ ID NO: 21.

[0280] In some embodiments, the first VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 1; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 4; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 8; and the second VH region comprises a VH CDR1 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 15; a VH CDR2 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 19; and a VH CDR3 comprising an amino acid sequence having at most one amino acid modification relative to SEQ ID NO: 21.

[0281] In some embodiments, the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 8, respectively; and the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 19, and SEQ ID NO: 21, respectively.

[0282] In some embodiments, the first VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 12, and the second VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 25. In some embodiments, the first VH region comprises the amino acid sequence of SEQ ID NO: 12, and the second VH region comprises the amino acid sequence of SEQ ID NO: 25.

[0283] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%,95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25, wherein the VH CDRs 1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0284] In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25, wherein the VH CDRs 1, 2, and 3 are defined by any one of Kabat, Chothia, or IMGT. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25, wherein the VH CDRs1, 2, and 3 are defined by Kabat. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1,2, and 3 of SEQ ID NO: 25, wherein the VH CDRs 1, 2, and 3 are defined by Chothia. In some embodiments, the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 12; and the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 25, wherein the VH CDRs 1, 2, and 3 are defined by IMGT.

[0285] Some embodiments of the present disclosure relate to heavy chain antibodies (e.g., anti-IL2RBG heavy-chain antibodies) comprising an Fc region that comprises an amino acid sequence that is at least 90% (e.g., at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%; 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%) identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, and a cysteine at position 302, all according to EU numbering.

[0286] In some embodiments, the Fc region comprises an amino acid sequence that is at least 91% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is at least 92% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is at least 93% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is at least 94% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is at least 96% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is at least 97% identical to the amino acid sequence of SEQ ID NO: 34.

[0287] In some embodiments, the Fc region comprises an amino acid sequence that is 97.4% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is 97.8% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is 98.2% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is 98.6% identical to the amino acid sequence of SEQ ID NO: 34.

[0288] In some embodiments, the Fc region comprises a first polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering. In some embodiments, the Fc region comprises a first polypeptide chain comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering. In some embodiments, the Fc region comprises a first polypeptide chain comprising an amino acid sequence that is between 90% and 97.8% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering.

[0289] In some embodiments, the first polypeptide chain comprises the amino acid sequence of SEQ ID NO: 35.

[0290] In some embodiments, the Fc region further comprises a second polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering. In some embodiments, the Fc region further comprises a second polypeptide chain comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering. In some embodiments, the Fc region further comprises a second polypeptide chain comprising an amino acid sequence that is between 90% and 97.4% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.

[0291] In some embodiments, the second polypeptide chain comprises the amino acid sequence of SEQ ID NO: 36.

[0292] In some embodiments, the Fc region comprises a first polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering; and a second polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.

[0293] In some embodiments, the Fc region comprises a first polypeptide chain comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering; and a second polypeptide chain comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.

[0294] In some embodiments, the Fc region comprises a first polypeptide chain comprising an amino acid sequence that is between 90% and 97.8% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering; and a second polypeptide chain comprising an amino acid sequence that is between 90% and 97.4% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.

[0295] In some embodiments, the first polypeptide chain comprises the amino acid sequence of SEQ ID NO: 35, and the second polypeptide chain comprises the amino acid sequence of SEQ ID NO: 36.

[0296] In some embodiments, the first heavy chain variable region is connected to the Fc region by a first peptide linker.

[0297] In some embodiments, the second heavy chain variable region is connected to the Fc region by a second peptide linker.

[0298] In some embodiments, the first heavy chain variable region is connected to the Fc region by a first peptide linker, and the second heavy chain variable region is connected to the Fc region by a second peptide linker.

[0299] In some embodiments, the first heavy chain variable region is connected to the first polypeptide chain of the Fc region by a first peptide linker, and the second heavy chain variable region is connected to the second polypeptide chain of the Fc region by a second peptide linker.

[0300] In some embodiments, the first heavy chain variable region is connected to the second polypeptide chain of the Fc region by a first peptide linker, and the second heavy chain variable region is connected to the first polypeptide chain of the Fc region by a second peptide linker.

[0301] In some embodiments, the first peptide linker and the second peptide linker have the same amino acid sequence. In other embodiments, the first peptide linker and the second peptide linker have different amino acid sequences.

[0302] In some embodiments, the first peptide linker comprises at least four amino acids (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10). In some embodiments, the second peptide linker comprises at least four amino acids (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10). In some embodiments, the first peptide linker comprises at least four amino acids, and the second peptide linker comprises at least four amino acids.

[0303] In some embodiments, the first peptide linker comprises between 4 and 10 amino acids. In some embodiments, the second peptide linker comprises between 4 and 10 amino acids. In some embodiments, the first peptide linker comprises between 4 and 10 amino acids, and the second peptide linker comprises between 4 and 10 amino acids.

[0304] In some embodiments, the first peptide linker comprises four amino acids. In some embodiments, the second peptide linker comprises four amino acids. In some embodiments, the first peptide linker comprises four amino acids, and the second peptide linker comprises four amino acids.

[0305] In some embodiments, the first peptide linker is a flexible linker. In some embodiments, the second peptide linker is a flexible linker. In some embodiments, the first peptide linker and the second peptide linker are both flexible linkers.

[0306] In some embodiments, the first peptide linker comprises glycine, serine, glutamine, and threonine amino acids. In some embodiments, the second peptide linker comprises glycine, serine, glutamine, and threonine amino acids. In some embodiments, the first peptide linker and the second peptide linker both comprise glycine, serine, glutamine, and threonine amino acids.

[0307] In some embodiments, the first peptide linker comprises glycine, serine, and threonine amino acids. In some embodiments, the second peptide linker comprises glycine, serine, and threonine amino acids. In some embodiments, the first peptide linker and the second peptide linker both comprise glycine, serine, and threonine amino acids.

[0308] In some embodiments, the first peptide linker comprises glycine, serine, glutamine, and threonine amino acids only. In some embodiments, the second peptide linker comprises glycine, serine, glutamine, and threonine amino acids only. In some embodiments, the first peptide linker and the second peptide linker both comprise glycine, serine, glutamine, and threonine amino acids only.

[0309] In some embodiments, the first peptide linker comprises glycine, serine, and threonine amino acids only. In some embodiments, the second peptide linker comprises glycine, serine, and threonine amino acids only. In some embodiments, the first peptide linker and the second peptide linker both comprise glycine, serine, and threonine amino acids only.

[0310] In some embodiments, the first peptide linker comprises the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)m, wherein m is a number in the range of 1 to 5 (SEQ ID NO: 40). In some embodiments, the second peptide linker comprises the amino acid sequence of (Gly-Gly-Gly-Gly- Ser)m, wherein m is a number in the range of 1 to 5 (SEQ ID NO: 40). In some embodiments, the first peptide linker and the second peptide linker both independently comprise amino acid sequences of (Gly-Gly-Gly-Gly-Ser)m, wherein m is a number in the range of 1 to 5 (SEQ ID NO: 40).

[0311] In some embodiments, the first peptide linker comprises the amino acid sequence of (Gly- Gly-Gly-Gly-Gln)n, wherein n is a number in the range of 1 to 5 (SEQ ID NO: 82). In someembodiments, the second peptide linker comprises the amino acid sequence of (Gly-Gly-Gly-Gly- Gln)n, wherein n is a number in the range of 1 to 5 (SEQ ID NO: 82). In some embodiments, the first peptide linker and the second peptide linker both independently comprise amino acid sequences of (Gly-Gly-Gly-Gly-Gln)n, wherein n is a number in the range of 1 to 5 (SEQ ID NO: 82).

[0312] In some embodiments, the first peptide linker is a poly-Gly linker. In some embodiments, the second peptide linker is a poly-Gly linker. In some embodiments, the first peptide linker and the second peptide linker are independently poly-Gly linkers.

[0313] In some embodiments, the first peptide linker comprises the amino acid sequence of (Gly)p, wherein p is a number in the range of 4 to 10 (SEQ ID NO: 41). In some embodiments, the second peptide linker comprises the amino acid sequence of (Gly)p, wherein p is a number in the range of 4 to 10 (SEQ ID NO: 41). In some embodiments, the first peptide linker and the second peptide linker both independently comprise amino acid sequences of (Gly)p, wherein p is a number in the range of 4 to 10 (SEQ ID NO: 41).

[0314] In some embodiments, the first peptide linker comprises the amino acid sequence of GGGG (SEQ ID NO: 37). In some embodiments, the second peptide linker comprises the amino acid sequence of GGGG (SEQ ID NO: 37). In some embodiments, the first peptide linker and the second peptide linker both comprise the amino acid sequence of GGGG (SEQ ID NO: 37).

[0315] Some embodiments of the present disclosure relate to heavy-chain antibodies (e.g., anti-IL2RBG heavy-chain antibodies) comprising a first heavy chain variable region, a second heavy chain variable region, and an Fc region, wherein the first heavy chain variable region is connected to the Fc region by a first peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids, and the second heavy chain variable region is connected to the Fc region by a second peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids.

[0316] In some embodiments, the first peptide linker and the second peptide linker have the same amino acid sequence. In other embodiments, the first peptide linker and the second peptide linker have different amino acid sequences.

[0317] In some embodiments, the first peptide linker comprises between 4 and 10 amino acids. In some embodiments, the second peptide linker comprises between 4 and 10 amino acids. In some embodiments, the first peptide linker comprises between 4 and 10 amino acids, and the second peptide linker comprises between 4 and 10 amino acids.

[0318] In some embodiments, the first peptide linker comprises four amino acids. In some embodiments, the second peptide linker comprises four amino acids. In some embodiments, the first peptide linker comprises four amino acids, and the second peptide linker comprises four amino acids.

[0319] In some embodiments, the first peptide linker is a flexible linker. In some embodiments, the second peptide linker is a flexible linker. In some embodiments, the first peptide linker and the second peptide linker are both flexible linkers.

[0320] In some embodiments, the first peptide linker comprises glycine, serine, glutamine, and threonine amino acids. In some embodiments, the second peptide linker comprises glycine, serine, glutamine, and threonine amino acids. In some embodiments, the first peptide linker and the second peptide linker both comprise glycine, serine, glutamine, and threonine amino acids.

[0321] In some embodiments, the first peptide linker comprises glycine, serine, and threonine amino acids. In some embodiments, the second peptide linker comprises glycine, serine, and threonine amino acids. In some embodiments, the first peptide linker and the second peptide linker both comprise glycine, serine, and threonine amino acids.

[0322] In some embodiments, the first peptide linker comprises glycine, serine, glutamine, and threonine amino acids only. In some embodiments, the second peptide linker comprises glycine, serine, glutamine, and threonine amino acids only. In some embodiments, the first peptide linker and the second peptide linker both comprise glycine, serine, glutamine, and threonine amino acids only.

[0323] In some embodiments, the first peptide linker comprises glycine, serine, and threonine amino acids only. In some embodiments, the second peptide linker comprises glycine, serine, and threonine amino acids only. In some embodiments, the first peptide linker and the second peptide linker both comprise glycine, serine, and threonine amino acids only.

[0324] In some embodiments, the first peptide linker comprises the amino acid sequence of (Gly- Gly-Gly-Gly-Ser)m, wherein m is a number in the range of 1 to 5 (SEQ ID NO: 40). In some embodiments, the second peptide linker comprises the amino acid sequence of (Gly-Gly-Gly-Gly- Ser)m, wherein m is a number in the range of 1 to 5 (SEQ ID NO: 40). In some embodiments, the first peptide linker and the second peptide linker both independently comprise amino acid sequences of (Gly-Gly-Gly-Gly-Ser)m, wherein m is a number in the range of 1 to 5 (SEQ ID NO: 40).

[0325] In some embodiments, the first peptide linker comprises the amino acid sequence of (Gly- Gly-Gly-Gly-Gln)n, wherein n is a number in the range of 1 to 5 (SEQ ID NO: 82). In some embodiments, the second peptide linker comprises the amino acid sequence of (Gly-Gly-Gly-Gly- Gln)n, wherein n is a number in the range of 1 to 5 (SEQ ID NO: 82). In some embodiments, the first peptide linker and the second peptide linker both independently comprise amino acid sequences of (Gly-Gly-Gly-Gly-Gln)n, wherein n is a number in the range of 1 to 5 (SEQ ID NO: 82).

[0326] In some embodiments, the first peptide linker is a poly-Gly linker. In some embodiments, the second peptide linker is a poly-Gly linker. In some embodiments, the first peptide linker and the second peptide linker are independently poly-Gly linkers.

[0327] In some embodiments, the first peptide linker comprises the amino acid sequence of (Gly)p, wherein p is a number in the range of 4 to 10 (SEQ ID NO: 41). In some embodiments, the second peptide linker comprises the amino acid sequence of (Gly)p, wherein p is a number in the range of 4 to 10 (SEQ ID NO: 41). In some embodiments, the first peptide linker and the second peptide linker both independently comprise amino acid sequences of (Gly)p, wherein p is a number in the range of 4 to 10 (SEQ ID NO: 41).

[0328] In some embodiments, the first peptide linker comprises the amino acid sequence of GGGG (SEQ ID NO: 37). In some embodiments, the second peptide linker comprises the amino acid sequence of GGGG (SEQ ID NO: 37). In some embodiments, the first peptide linker and the second peptide linker both comprise the amino acid sequence of GGGG (SEQ ID NO: 37).

[0329] In some embodiments, the Fc region is a variant Fc region. In some embodiments, the variant Fc region comprises heterodimerizing alterations. In some embodiments, the Fc region is a silenced Fc region.

[0330] In some embodiments, the Fc region comprises an amino acid sequence that is at least 90% (e.g., at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%; 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%) identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, and a cysteine at position 302, all according to EU numbering.

[0331] In some embodiments, the Fc region comprises an amino acid sequence that is at least 91% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is at least 92% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is at least 93% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is at least 94% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is at least 96% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is at least 97% identical to the amino acid sequence of SEQ ID NO: 34.

[0332] In some embodiments, the Fc region comprises an amino acid sequence that is 97.4% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc regioncomprises an amino acid sequence that is 97.8% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is 98.2% identical to the amino acid sequence of SEQ ID NO: 34. In some embodiments, the Fc region comprises an amino acid sequence that is 98.6% identical to the amino acid sequence of SEQ ID NO: 34.

[0333] In some embodiments, the Fc region comprises a first polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering. In some embodiments, the Fc region comprises a first polypeptide chain comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering. In some embodiments, the Fc region comprises a first polypeptide chain comprising an amino acid sequence that is between 90% and 97.8% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering.

[0334] In some embodiments, the first polypeptide chain comprises the amino acid sequence of SEQ ID NO: 35.

[0335] In some embodiments, the Fc region further comprises a second polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering. In some embodiments, the Fc region further comprises a second polypeptide chain comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering. In some embodiments, the Fc region further comprises a second polypeptide chain comprising an amino acid sequence that is between 90% and 97.4% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.

[0336] In some embodiments, the second polypeptide chain comprises the amino acid sequence of SEQ ID NO: 36.

[0337] In some embodiments, the Fc region comprises a first polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering; and a second polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.

[0338] In some embodiments, the Fc region comprises a first polypeptide chain comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering; and a second polypeptide chain comprising an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.

[0339] In some embodiments, the Fc region comprises a first polypeptide chain comprising an amino acid sequence that is between 90% and 97.8% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering; and a second polypeptide chain comprising an amino acid sequence that is between 90% and 97.4% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.

[0340] In some embodiments, the first polypeptide chain comprises the amino acid sequence of SEQ ID NO: 35, and the second polypeptide chain comprises the amino acid sequence of SEQ ID NO: 36.

[0341] In some embodiments, the first heavy chain variable region is connected to the first polypeptide chain of the Fc region by the first peptide linker, and the second heavy chain variable region is connected to the second polypeptide chain of the Fc region by the second peptide linker.

[0342] In some embodiments, the first heavy chain variable region is connected to the second polypeptide chain of the Fc region by the first peptide linker, and the second heavy chain variable region is connected to the first polypeptide chain of the Fc region by the second peptide linker.

[0343] In some embodiments, the Fc region comprises a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 35 and a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 36; and the first peptide linker and the second peptide linker independently comprise the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)m, wherein m is a number in the range of I to 5 (SEQ ID NO: 40).

[0344] In some embodiments, the Fc region comprises a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 35 and a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 36; and the first peptide linker and the second peptide linker independently comprise the amino acid sequence of (Gly-Gly-Gly-Gly-Gln)n, wherein n is a number in the range of I to 5 (SEQ ID NO: 82).

[0345] In some embodiments, the Fc region comprises a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 35 and a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 36; and the first peptide linker and the second peptide linker are independently poly-Gly linkers.

[0346] In some embodiments, the Fc region comprises a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 35 and a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 36; and the first peptide linker and the second peptide linker independently comprise the amino acid sequence of (Gly)p, wherein p is a number in the range of 4 to 10 (SEQ ID NO: 41).

[0347] In some embodiments, the Fc region comprises a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 35 and a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 36; and the first peptide linker and the second peptide linker both comprise the amino acid sequence of GGGG (SEQ ID NO: 37).

[0348] Also provided herein is a heavy-chain antibody comprising: a first VH region that binds to IL2RB, wherein the first VH region comprises a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of SEQ ID NO: 2, SEQ ID NO: 5, and SEQ ID NO: 9, respectively; a second VH region that binds to IL2RG, wherein the second VH region comprises a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 18, and SEQ ID NO: 20, respectively; andan Fc region that comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, and a cysteine at position 302, all according to EU numbering.

[0349] Also provided herein is a heavy-chain antibody comprising: a first VH region that binds to IL2RB, wherein the first VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 13; a second VH region that binds to IL2RG, wherein the second VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 23; and an Fc region that comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, and a cysteine at position 302, all according to EU numbering.

[0350] In some embodiments, the first VH region comprises the amino acid sequence of SEQ ID NO: 13. In some embodiments, the second VH region comprises the amino acid sequence of SEQ ID NO: 23. In some embodiments, the first VH region comprises the amino acid sequence of SEQ ID NO: 13, and the second VH region comprises the amino acid sequence of SEQ ID NO: 23.

[0351] Also provided herein is a heavy-chain antibody comprising: a first VH region that binds to IL2RB, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13; a second VH region that binds to IL2RG, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23; and an Fc region that comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, and a cysteine at position 302, all according to EU numbering.

[0352] Also provided herein is a heavy-chain antibody comprising: a first VH region that binds to IL2RB, wherein the first VH region comprises a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of SEQ ID NO: 2, SEQ ID NO: 5, and SEQ ID NO: 9, respectively; a second VH region that binds to IL2RG, wherein the second VH region comprises a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 18, and SEQ ID NO: 20, respectively; and an Fc region, wherein the first heavy chain variable region is connected to the Fc region by a first peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids, and the second heavy chain variable region is connected to the Fc region by a second peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids.

[0353] Also provided herein is a heavy-chain antibody comprising: a first VH region that binds to IL2RB, wherein the first VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 13; a second VH region that binds to IL2RG, wherein the second VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 23; and an Fc region, wherein the first heavy chain variable region is connected to the Fc region by a first peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids, and the second heavy chain variable region is connected to the Fc region by a second peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids.

[0354] In some embodiments, the first VH region comprises the amino acid sequence of SEQ ID NO: 13. In some embodiments, the second VH region comprises the amino acid sequence of SEQ ID NO: 23. In some embodiments, the first VH region comprises the amino acid sequence of SEQ ID NO: 13, and the second VH region comprises the amino acid sequence of SEQ ID NO: 23.

[0355] Also provided herein is a heavy-chain antibody comprising: a first VH region that binds to IL2RB, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the first VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 13; a second VH region that binds to IL2RG, wherein the full set of VH CDRs 1, 2, and 3 (combined) in the second VH region is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to the VH CDRs 1, 2, and 3 of SEQ ID NO: 23; and an Fc region, wherein the first heavy chain variable region is connected to the Fc region by a first peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids, and the second heavy chain variable region is connected to the Fc region by a second peptide linker comprising at least four (e.g., at least 5, at least 6, at least 7, at least 8, at least 9, at least 10; between 4 and 10, between 4 and 9, between 4 and 8, between 4 and 7, between 4 and 6; 4, 5, 6, 7, 8, 9, 10) amino acids.

[0356] Also provided herein is a heavy-chain antibody comprising: a first VH region that binds to IL2RB, wherein the first VH region comprises a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of SEQ ID NO: 2, SEQ ID NO: 5, and SEQ ID NO: 9, respectively; a second VH region that binds to IL2RG, wherein the second VH region comprises a VH CDR1, a VH CDR2, and a VH CDR3 comprising the amino acid sequences of SEQ ID NO: 15, SEQ ID NO: 18, and SEQ ID NO: 20, respectively; and an Fc region comprising a first polypeptide chain and a second polypeptide chain, wherein the first polypeptide chain comprises the amino acid sequence of SEQ ID NO: 35, and the second polypeptide chain comprises the amino acid sequence of SEQ ID NO: 36.

[0357] In some embodiments, the first VH region is connected to the Fc region by a first peptide linker. In some embodiments, the second VH region is connected to the Fc region by a second peptide linker. In some embodiments, the first heavy chain variable region is connected to the first polypeptide chain of the Fc region by a first peptide linker, and the second heavy chain variable region is connected to the second polypeptide chain of the Fc region by a second peptide linker.

[0358] In some embodiments, the first peptide linker and the second peptide linker independently comprise the amino acid sequence of (Gly-Gly-Gly-Gly-Ser)m, wherein m is a number in the range of I to 5 (SEQ ID NO: 40).

[0359] In some embodiments, the first peptide linker and the second peptide linker independently comprise the amino acid sequence of (Gly-Gly-Gly-Gly-Gln)n, wherein n is a number in the range of I to 5 (SEQ ID NO: 82).

[0360] In some embodiments, the first peptide linker and the second peptide linker independently comprise the amino acid sequence of (Gly)p, wherein p is a number in the range of 4 to 10 (SEQ ID NO: 41).

[0361] In some embodiments, the first peptide linker and the second peptide linker both comprise the amino acid sequence of GGGG (SEQ ID NO: 37).

[0362] Also provided herein is a heavy-chain antibody comprising: a first VH region that binds to IL2RB, wherein the first VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 13; a second VH region that binds to IL2RG, wherein the second VH region comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 90%, at least 95%; 80%, 85%, 90%, 95%) identical to SEQ ID NO: 23; and an Fc region comprising a first polypeptide chain and a second polypeptide chain, wherein the first polypeptide chain comprises the amino acid sequence of SEQ ID NO: 35, and the second polypeptide chain comprises the amino acid sequence of SEQ ID NO: 36.

[0363] In some...

Claims

What is claimed is:

1. A heavy-chain antibody comprising: a first heavy chain variable (VH) region that binds to IL2RB comprising:(a) a VH complementarity determining region one (CDR1) comprising the amino acid sequence:G G S I S S S X1 W (SEQ ID NO: 26), wherein XI is D or N;(b) a VH CDR2 comprising the amino acid sequence:I X2 H S G S T (SEQ ID NO: 27), wherein X2 is D or S; and(c) a VH CDR3 comprising the amino acid sequence:X3 R G X4 W E L X5 D A F D I (SEQ ID NO: 28), wherein X3 is G or A; X4 is S or Q; and X5 is S or T; a second heavy chain variable region that binds to IL2RG comprising:(a) a VH CDR1 comprising the amino acid sequence:G F XI X2 X3 X4 Y Y (SEQ ID NO: 32), wherein XI is T or I; X2 is F or V; X3 is S, N, or G; and X4 is D or N;(b) a VH CDR2 comprising the amino acid sequence:I S X5 S G X6 X7 I (SEQ ID NO: 33), wherein X5 is S or N; X6 is D, S, G, or N; and X7 is T or I; and(c) a VH CDR3 comprising the amino acid sequence ARGDAVSITGDY (SEQ ID NO: 20); and an Fc region comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, and a cysteine at position 302, all according to EU numbering.

2. The heavy-chain antibody of claim 1, wherein the Fc region comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34.

3. The heavy-chain antibody of claim 1, wherein the Fc region comprises: a first polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering; and a second polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycineat position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.

4. The heavy-chain antibody of claim 3, wherein the first polypeptide chain comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, and the second polypeptide chain comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34.

5. The heavy-chain antibody of claim 3 or claim 4, wherein the first polypeptide chain comprises the amino acid sequence of SEQ ID NO: 35, and the second polypeptide chain comprises the amino acid sequence of SEQ ID NO: 36.

6. The heavy-chain antibody of any one of claims 1-5, wherein the first heavy chain variable region is connected to the Fc region by a first peptide linker, and the second heavy chain variable region is connected to the Fc region by a second peptide linker.

7. The heavy-chain antibody of claim 6, wherein the first peptide linker and the second peptide linker are independently poly-Gly linkers.

8. The heavy-chain antibody of claim 6 or claim 7, wherein the first peptide linker and the second peptide linker both comprise the amino acid sequence of GGGG (SEQ ID NO: 37).

9. A heavy-chain antibody comprising: a first heavy chain variable (VH) region that binds to IL2RB comprising:(a) a VH complementarity determining region one (CDR1) comprising the amino acid sequence:G G S I S S S X1 W (SEQ ID NO: 26), wherein XI is D or N;(b) a VH CDR2 comprising the amino acid sequence:I X2 H S G S T (SEQ ID NO: 27), wherein X2 is D or S; and(c) a VH CDR3 comprising the amino acid sequence:X3 R G X4 W E L X5 D A F D I (SEQ ID NO: 28), wherein X3 is G or A; X4 is S or Q; and X5 is S or T; a second heavy chain variable region that binds to IL2RG comprising:(a) a VH CDR1 comprising the amino acid sequence:G F XI X2 X3 X4 Y Y (SEQ ID NO: 32), wherein XI is T or I; X2 is F or V; X3 is S, N, or G; and X4 is D or N;(b) a VH CDR2 comprising the amino acid sequence:I S X5 S G X6 X7 I (SEQ ID NO: 33), wherein X5 is S or N; X6 is D, S, G, or N; and X7 is T or I; and(c) a VH CDR3 comprising the amino acid sequence ARGDAVSITGDY (SEQ ID NO: 20); and an Fc region, wherein the first heavy chain variable region is connected to the Fc region by a first peptide linker comprising at least four amino acids, and the second heavy chain variable region is connected to the Fc region by a second peptide linker comprising at least four amino acids.

10. The heavy-chain antibody of claim 9, wherein the first peptide linker and the second peptide linker are both flexible linkers.

11. The heavy-chain antibody of claim 9 or claim 10, wherein the first peptide linker and the second peptide linker are independently poly-Gly linkers.

12. The heavy-chain antibody of any one of claims 9-11, wherein the first peptide linker and the second peptide linker both comprise the amino acid sequence of GGGG (SEQ ID NO: 37).

13. The heavy-chain antibody of any one of claims 9-12, wherein the Fc region comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, and a cysteine at position 302, all according to EU numbering.

14. The heavy-chain antibody of any one of claims 9-13, wherein the Fc region comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34.

15. The heavy-chain antibody of any one of claims 9-12, wherein the Fc region comprises: a first polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycine at position 297, a cysteine at position 292, a cysteine at position 302, a lysine at position 356, and a lysine at position 399, all according to EU numbering; and a second polypeptide chain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, wherein the amino acid sequence comprises a glycineat position 297, a cysteine at position 292, a cysteine at position 302, an aspartic acid at position 392, an aspartic acid at position 409, and an aspartic acid at position 439, all according to EU numbering.

16. The heavy-chain antibody of claim 15, wherein the first polypeptide chain comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34, and the second polypeptide chain comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 34.

17. The heavy-chain antibody of claim 15 or claim 16, wherein the first polypeptide chain comprises the amino acid sequence of SEQ ID NO: 35, and the second polypeptide chain comprises the amino acid sequence of SEQ ID NO: 36.

18. The heavy-chain antibody of claim 9, wherein: the Fc region comprises a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 35 and a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 36; and the first peptide linker and the second peptide linker are independently poly-Gly linkers.

19. The heavy-chain antibody of claim 9 or claim 18, wherein: the Fc region comprises a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 35 and a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 36; and the first peptide linker and the second peptide linker both comprise the amino acid sequence of GGGG (SEQ ID NO: 37).

20. The heavy-chain antibody of any one of claims 1-19, wherein the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of SEQ ID NO: 1 or SEQ ID NO: 2; SEQ ID NO: 4 or SEQ ID NO: 5; and SEQ ID NO: 7, SEQ ID NO: 8, or SEQ ID NO: 9, respectively.

21. The heavy-chain antibody of any one of claims 1-20, wherein the VH CDR1, the VH CDR2, and the VH CDR3 of the first VH region comprise the amino acid sequences of:(a) SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 7, respectively; or(b) SEQ ID NO: 1, SEQ ID NO: 4, and SEQ ID NO: 8, respectively; or(c) SEQ ID NO: 2, SEQ ID NO: 5, and SEQ ID NO: 9, respectively.

22. The heavy-chain antibody of any one of claims 1-21, wherein the first VH region comprises an amino acid sequence that is at least 95% identical to any one of SEQ ID NOs: 11-13.

23. The heavy-chain antibody of any one of claims 1-22, wherein the first VH region comprises an amino acid sequence selected from SEQ ID NOs: 11-13.

24. The heavy-chain antibody of any one of claims 1-23, wherein the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of SEQ ID NO: 15 or SEQ ID NO: 16; SEQ ID NO: 17 or SEQ ID NO: 18; and SEQ ID NO: 20, respectively.

25. The heavy-chain antibody of any one of claims 1-24, wherein the VH CDR1, the VH CDR2, and the VH CDR3 of the second VH region comprise the amino acid sequences of:(a) SEQ ID NO: 15, SEQ ID NO: 17, and SEQ ID NO: 20, respectively; or(b) SEQ ID NO: 15, SEQ ID NO: 18, and SEQ ID NO: 20, respectively; or(c) SEQ ID NO: 16, SEQ ID NO: 18, and SEQ ID NO: 20, respectively.

26. The heavy-chain antibody of any one of claims 1-25, wherein the second VH region comprises an amino acid sequence that is at least 95% identical to any one of SEQ ID NOs: 22-24.

27. The heavy-chain antibody of any one of claims 1-26, wherein the second VH region comprises an amino acid sequence selected from SEQ ID NOs: 22-24.

28. The heavy-chain antibody of any one of claims 1-27, wherein the first VH region comprises the amino acid sequence of SEQ ID NO: 13, and the second VH region comprises the amino acid sequence of SEQ ID NO: 23.

29. A heavy-chain antibody comprising: a first heavy chain that binds to IL2RB comprising the amino acid sequence of SEQ IDNO: 38; and a second heavy chain that binds to IL2RG comprising the amino acid sequence of SEQ ID NO: 39.

30. A pharmaceutical composition comprising: a heavy-chain antibody of any one of claims 1-29; and a pharmaceutically acceptable excipient.

31. The pharmaceutical composition of claim 30, wherein the pharmaceutical composition is adapted for intravenous or subcutaneous administration.

32. A method of treating cancer in a subject in need thereof, comprising administering to the subject a heavy-chain antibody of any one of claims 1-29 or a pharmaceutical composition of claim 30 or claim 31.

33. A method of treating cancer in a subject in need thereof, comprising administering to the subject a heavy-chain antibody of any one of claims 1-29 or a pharmaceutical composition of claim 30 or claim 31 in combination with a T-cell redirecting therapy.

34. A method of enhancing an anti-cancer effect associated with administration of a T-cell redirecting therapy in a subject diagnosed with cancer, comprising administering to the subject a heavy-chain only antibody of any one of claims 1-29 or a pharmaceutical composition of claim 30 or claim 31 in combination with the T-cell redirecting therapy.

35. The method of claim 33 or claim 34, wherein the T-cell redirecting therapy is a bispecific T- cell engaging molecule.

36. The method of claim 35, wherein the bispecific T-cell engaging molecule is tarlatamab.

37. A method of treating a DLL3 -expressing cancer in a subject in need thereof, comprising administering to the subject an IL-2 -based therapy in combination with a T-cell redirecting therapy that binds to DLL3.

38. The method of claim 37, wherein the DLL3 -expressing cancer is a neuroendocrine cancer.

39. The method of claim 37 or claim 38, wherein the T-cell redirecting therapy that binds to DLL3 is tarlatamab.

40. The method of any one of claims 37-39, wherein the IL-2 -based therapy preferentially binds to the heterodimeric receptor composed only of IL 2Rj3 and IL 2Ry over the trimeric IL-2RaPy form of the IL-2 receptor.

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