IL15 / IL15R alpha heterodimeric FC fusion protein for the treatment of hematological cancers

Abstract

The present disclosure provides a method of treating hematological cancers, such as multiple myeloma, by administering a heterodimeric protein comprising a first monomer comprising an IL15 protein-Fc domain fusion and a second monomer comprising an IL15Rα protein-Fc domain fusion.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Provisional Application No. 63 / 226,359, filed July 28, 2021, the entire contents of which are incorporated herein by reference.

[0002] Technical Field The present disclosure relates to the field of treatment of hematological cancers, such as multiple myeloma, using IL15-IL15R heterodimeric Fc fusion proteins.

[0003] Sequence Listing This application contains a Sequence Listing that has been submitted electronically in XML format, which is incorporated herein by reference in its entirety. The XML copy, created on July 27, 2022, is named 000218-0046-WO1_SL.xml and is 60,483 bytes in size. [Background technology]

[0004] background Most blood cancers (or hematological cancers) originate in the bone marrow and result from abnormal blood cells that grow uncontrollably, interrupting the normal blood cells' function of fighting off infection and producing new blood cells. Multiple myeloma (MM), a type of blood cancer, is an incurable neoplasm characterized by the proliferation and accumulation of malignant plasma cells in the bone marrow, resulting in the overproduction of a monoclonal protein (M protein) detectable in the blood or urine of most subjects. Approximately 30,000 people are diagnosed with MM annually in the United States (Siegel et al., 2019), and approximately 160,000 people worldwide are diagnosed with MM annually (Bray et al., 2018). End-organ damage resulting from MM includes hypercalcemia, renal insufficiency, anemia, and lytic bone lesions. MM remains incurable despite advances in treatment, with aggressive treatment therapies such as autologous stem cell transplantation (ASCT) resulting in an estimated median survival of 8-10 years for standard-risk and 2-3 years for high-risk myeloma (Mikhael et al., 2013). Prolonged survival has been achieved with the introduction of proteasome inhibitors (PIs) such as bortezomib (Velcade® USPackage Insert [USPI]), immunomodulatory drugs (IMiDs) such as lenalidomide (Revlimid® USPI), and monoclonal antibodies such as daratumumab (Darzalex® USPI, Darzalex-Faspro™ USPI). Other agents with novel mechanisms of action approved by the US Food and Drug Administration for the treatment of MM include the nuclear export inhibitors Selinexor (Xpovio™ USPI) and belantamab mafodotin-blmf (Blenrep USPI).

[0005] Despite significant advances in treatment options, most MM patients eventually relapse. Relapsed / refractory multiple myeloma (R / R MM) still constitutes a significant unmet medical need, with median overall survival less than one year in subjects with disease refractory to anti-CD38 monoclonal antibodies (Chari et al., 2019; Gandi et al., 2019). Several approaches to instruct the human immune system to target and destroy malignant plasma cells are currently being investigated in clinical settings, including T-cell-engaging bispecific antibodies and chimeric antigen receptor [CAR] T cells. Emerging data from clinical trials using these agents suggest that manipulating a subject's immune system is a potentially promising approach for the treatment of R / R MM (Moreau et al., 2019; Caraccio et al., 2020). Summary of the Invention

[0006] overview In a first aspect, the disclosure provides a method of treating hematological cancer in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain; and (ii) a second monomer comprising the sushi domain of an IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain, wherein the IL-15 protein comprises an N65D amino acid substitution and one or more amino acid substitutions selected from the group consisting of N4D, D30N, and E64Q.

[0007] In a second aspect, the present disclosure provides a method for detecting CD8 +The present invention provides a method for inducing proliferation of effector memory T cells, comprising administering to a subject an effective amount of a heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain; and (ii) a second monomer comprising the sushi domain of an IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain, wherein the IL-15 protein comprises an N65D amino acid substitution and one or more amino acid substitutions selected from the group consisting of N4D, D30N, and E64Q.

[0008] In a third aspect, the disclosure provides a method for inducing proliferation of NK cells in a subject suffering from a hematological cancer, comprising administering to the subject an effective amount of a heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain; and (ii) a second monomer comprising the sushi domain of an IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain, wherein the IL-15 protein comprises an N65D amino acid substitution and one or more amino acid substitutions selected from the group consisting of N4D, D30N, and E64Q.

[0009] In a fourth aspect, a method for detecting CD8 +The present invention provides a method for inducing proliferation of effector memory T cells and NK cells, comprising administering to a subject an effective amount of a heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain; and (ii) a second monomer comprising the sushi domain of an IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain, wherein the IL-15 protein comprises an N65D amino acid substitution and one or more amino acid substitutions selected from the group consisting of N4D, D30N, and E64Q.

[0010] In a fifth aspect, there is provided a method for inducing IFNγ production in a subject suffering from a hematological cancer, comprising administering to the subject an effective amount of a heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain; and (ii) a second monomer comprising the sushi domain of an IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain, wherein the IL-15 protein comprises an N65D amino acid substitution and one or more amino acid substitutions selected from the group consisting of N4D, D30N, E64Q.

[0011] In some embodiments, the first Fc domain and the second Fc domain each contain the amino acid substitutions E233P, L234V, L235A, G236del, and S267K according to EU numbering.

[0012] In some embodiments, the first Fc domain further comprises amino acid substitutions L368D and K370S according to EU numbering, and the second Fc domain further comprises amino acid substitutions S364K and E357Q according to EU numbering. In some embodiments, the first Fc domain further comprises amino acid substitutions S364K and E357Q according to EU numbering, and the second Fc domain further comprises amino acid substitutions L368D and K370S according to EU numbering. In some embodiments, the first Fc domain further comprises amino acid substitutions Q295E, N384D, Q418E, and N421D according to EU numbering.

[0013] In some embodiments, the second Fc domain further comprises the amino acid substitutions Q295E, N384D, Q418E and N421D according to EU numbering. In some embodiments, the second Fc domain further comprises the amino acid substitution K246T according to EU numbering.

[0014] In some embodiments, the IL-15 protein comprises the amino acid substitutions D30N, E64Q and N65D. In some embodiments, the IL-15 protein comprises the amino acid sequence shown in SEQ ID NO:5.

[0015] In some embodiments, the sushi domain of the IL-15Rα protein comprises the amino acid sequence set forth in SEQ ID NO:4.

[0016] In some embodiments, the IL-15 protein is covalently linked to the N-terminus of the first Fc domain via a first linker.

[0017] In some embodiments, the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain via a second linker.

[0018] In some embodiments, the IL-15 protein is covalently linked to the N-terminus of a first Fc domain via a first linker, and the IL-15Rα protein is covalently linked to the N-terminus of a second Fc domain via a second linker.

[0019] In some embodiments, the first linker and / or the second linker are independently a variable length Gly-Ser linker. In some embodiments, the first linker and / or the second linker independently comprise a linker selected from the group consisting of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO:39), (Ser-Ser-Ser-Ser-Gly)n (SEQ ID NO:40), (Gly-Ser-Ser-Gly-Gly)n (SEQ ID NO:41), and (Gly-Gly-Ser-Gly-Gly)n (SEQ ID NO:42), where n is an integer from 1 to 5.

[0020] In a sixth aspect, the disclosure provides a method of treating a hematological cancer in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a heterodimeric protein, the heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to an N-terminus of the first Fc domain; and (ii) a second monomer comprising an IL-15Rα protein and a second Fc domain, wherein the IL-15Rα protein is covalently linked to an N-terminus of the second Fc domain, wherein the first Fc domain and the second Fc domain have the sequence numbers S267K / L368D / K370S:S267K / S364D / K370S according to EU numbering. K / E357Q;S364K / E357Q:L368D / K370S;L368D / K370S:S364K;L368E / K370S:S364K;T411E / K360E / Q3 62E:D401K;L368D / K370S:S364K / E357L;K370S:S364K / E357Q;S267K / S364K / E357Q:S267K / L368D / K 370S; L368D / K370S:S364K / E357Q; S364K:L368D / K370S; S364K:L368E / K370S; D401K:T411E / K360E / Q362E; S364K / E357L:L368D / K370S; and S364K / E357Q:K370S.

[0021] In a seventh aspect, the present disclosure provides a method for detecting CD8 +1. A method for inducing proliferation of effector memory T cells, comprising administering to a subject an effective amount of a heterodimeric protein, the heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to an N-terminus of the first Fc domain; and (ii) a second monomer comprising an IL-15Rα protein and a second Fc domain, wherein the IL-15Rα protein is covalently linked to an N-terminus of the second Fc domain, the first Fc domain and the second Fc domain having the sequence numbers S267K / L368D / K370S:S267K / S364K / E357Q;S3 ... 64K / E357Q:L368D / K370S;L368D / K370S:S364K;L368E / K370S:S364K;T411E / K360E / Q362E:D401 K;L368D / K370S:S364K / E357L;K370S:S364K / E357Q;S267K / S364K / E357Q:S267K / L368D / K370S; The method includes a set of amino acid substitutions selected from the group consisting of: L368D / K370S:S364K / E357Q; S364K:L368D / K370S; S364K:L368E / K370S; D401K:T411E / K360E / Q362E; S364K / E357L:L368D / K370S; and S364K / E357Q:K370S.

[0022] In an eighth aspect, the disclosure provides a method for inducing proliferation of NK cells in a subject suffering from a hematological cancer, comprising administering to the subject an effective amount of a heterodimeric protein, the heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to an N-terminus of the first Fc domain; and (ii) a second monomer comprising an IL-15Rα protein and a second Fc domain, wherein the IL-15Rα protein is covalently linked to an N-terminus of the second Fc domain, wherein the first Fc domain and the second Fc domain have the sequence numbers S267K / L368D / K370S:S267K / S36 4K / E357Q;S364K / E357Q:L368D / K370S;L368D / K370S:S364K;L368E / K370S:S364K;T411E / K360E / Q3 62E:D401K;L368D / K370S:S364K / E357L;K370S:S364K / E357Q;S267K / S364K / E357Q:S267K / L368D / K 370S; L368D / K370S:S364K / E357Q; S364K:L368D / K370S; S364K:L368E / K370S; D401K:T411E / K360E / Q362E; S364K / E357L:L368D / K370S; and S364K / E357Q:K370S.

[0023] In a ninth aspect, the present disclosure provides a method for detecting CD8 +1. A method for inducing proliferation of effector memory T cells, comprising administering to a subject an effective amount of a heterodimeric protein, the heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to an N-terminus of the first Fc domain; and (ii) a second monomer comprising an IL-15Rα protein and a second Fc domain, wherein the IL-15Rα protein is covalently linked to an N-terminus of the second Fc domain, the first Fc domain and the second Fc domain having the sequence numbers S267K / L368D / K370S:S267K / S364K / E357Q;S3 ... 64K / E357Q:L368D / K370S;L368D / K370S:S364K;L368E / K370S:S364K;T411E / K360E / Q362E:D401 K;L368D / K370S:S364K / E357L;K370S:S364K / E357Q;S267K / S364K / E357Q:S267K / L368D / K370S; The method includes a set of amino acid substitutions selected from the group consisting of: L368D / K370S:S364K / E357Q; S364K:L368D / K370S; S364K:L368E / K370S; D401K:T411E / K360E / Q362E; S364K / E357L:L368D / K370S; and S364K / E357Q:K370S.

[0024] In a tenth aspect, the disclosure provides a method for inducing proliferation of NK cells in a subject suffering from a hematological cancer, comprising administering to the subject an effective amount of a heterodimeric protein, the heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to an N-terminus of the first Fc domain; and (ii) a second monomer comprising an IL-15Rα protein and a second Fc domain, wherein the IL-15Rα protein is covalently linked to an N-terminus of the second Fc domain, wherein the first Fc domain and the second Fc domain have the sequence numbers S267K / L368D / K370S:S267K / S36 4K / E357Q;S364K / E357Q:L368D / K370S;L368D / K370S:S364K;L368E / K370S:S364K;T411E / K360E / Q3 62E:D401K;L368D / K370S:S364K / E357L;K370S:S364K / E357Q;S267K / S364K / E357Q:S267K / L368D / K 370S; L368D / K370S:S364K / E357Q; S364K:L368D / K370S; S364K:L368E / K370S; D401K:T411E / K360E / Q362E; S364K / E357L:L368D / K370S; and S364K / E357Q:K370S.

[0025] In an eleventh aspect, the present disclosure provides a method for detecting CD8 +1. A method for inducing proliferation of effector memory T cells and NK cells, comprising administering to a subject an effective amount of a heterodimeric protein, the heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to an N-terminus of the first Fc domain; and (ii) a second monomer comprising an IL-15Rα protein and a second Fc domain, wherein the IL-15Rα protein is covalently linked to an N-terminus of the second Fc domain, wherein the first Fc domain and the second Fc domain have the sequence numbers S267K / L368D / K370S:S267K / S364K / E357 according to EU numbering. Q;S364K / E357Q:L368D / K370S;L368D / K370S:S364K;L368E / K370S:S364K;T411E / K360E / Q362E:D 401K;L368D / K370S:S364K / E357L;K370S:S364K / E357Q;S267K / S364K / E357Q:S267K / L368D / K370 S;L368D / K370S:S364K / E357Q; S364K:L368D / K370S; S364K:L368E / K370S; D401K:T411E / K360E / Q362E; S364K / E357L:L368D / K370S; and S364K / E357Q:K370S.

[0026] In a twelfth aspect, the disclosure provides a method for inducing IFNγ production in a subject suffering from a hematological cancer, comprising administering to the subject an effective amount of a heterodimeric protein, the heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to an N-terminus of the first Fc domain; and (ii) a second monomer comprising an IL-15Rα protein and a second Fc domain, wherein the IL-15Rα protein is covalently linked to an N-terminus of the second Fc domain, wherein the first Fc domain and the second Fc domain have the sequence numbers S267K / L368D / K370S:S267K / S36 4K / E357Q;S364K / E357Q:L368D / K370S;L368D / K370S:S364K;L368E / K370S:S364K;T411E / K360E / Q3 62E:D401K;L368D / K370S:S364K / E357L;K370S:S364K / E357Q;S267K / S364K / E357Q:S267K / L368D / K 370S; L368D / K370S:S364K / E357Q; S364K:L368D / K370S; S364K:L368E / K370S; D401K:T411E / K360E / Q362E; S364K / E357L:L368D / K370S; and S364K / E357Q:K370S.

[0027] In some embodiments, the first Fc domain and / or the second Fc domain independently further comprise the amino acid substitutions Q295E, N384D, Q418E and N421D according to EU numbering.

[0028] In some embodiments, the first Fc domain and / or the second Fc domain independently further comprise an amino acid substitution selected from the group consisting of: G236R / L328R; E233P / L234V / L235A / G236del / S239K; E233P / L234V / L235A / G236del / S267K; E233P / L234V / L235A / G236del / S239K / A327G; E233P / L234V / L235A / G236del / S267K / A327G; and E233P / L234V / L235A / G236del, according to EU numbering, and wherein the Fc domain is derived from an IgG1 or IgG3 Fc domain.

[0029] In some embodiments, the first Fc domain and / or the second Fc domain independently further comprise an amino acid substitution selected from the group consisting of: L328R; S239K; and S267K according to EU numbering, and wherein the Fc domain is derived from an IgG2 Fc domain.

[0030] In some embodiments, the first Fc domain and / or the second Fc domain independently further comprise an amino acid substitution selected from the group consisting of: G236R / L328R; E233P / F234V / L235A / G236del / S239K; E233P / F234V / L235A / G236del / S267K; E233P / F234V / L235A / G236del / S239K / A327G; E233P / F234V / L235A / G236del / S267K / A327G; and E233P / F234V / L235A / G236del, according to EU numbering, wherein the Fc domain is derived from an IgG4 Fc domain.

[0031] In some embodiments, the IL-15 protein comprises one or more amino acid substitutions selected from the group consisting of N1D, N4D, D8N, D30N, D61N, E64Q, N65D and Q108E.

[0032] In some embodiments, the IL-15 protein and the IL-15Rα protein each comprise a set of amino acid substitutions or additions selected from E87C:65DPC; E87C:65DCA; V49C:S40C; L52C:S40C; E89C:K34C; Q48C:G38C; E53C:L42C; C42S:A37C and L45C:A37C.

[0033] In some embodiments, the IL-15 protein comprises a polypeptide sequence selected from the group consisting of SEQ ID NO:1 and SEQ ID NO:2.

[0034] In some embodiments, the IL-15Rα protein comprises a polypeptide sequence selected from the group consisting of SEQ ID NO:3 and SEQ ID NO:4.

[0035] In some embodiments, the first Fc domain comprises amino acid substitutions L368D and K370S; the second Fc domain further comprises amino acid substitutions S364K and E357Q; the first Fc domain and the second Fc domain each further comprise amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, M428L, and N434S according to EU numbering; the IL-15 protein comprises amino acid substitutions D30N, E64Q, and N65D; and the IL-15Rα protein comprises SEQ ID NO:4.

[0036] In some embodiments, the first Fc domain comprises amino acid substitutions S364K and E357Q; the second Fc domain comprises amino acid substitutions L368D and K370S; the first Fc domain and the second Fc domain each further comprise amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, M428L, and N434S according to EU numbering; the IL-15 protein comprises amino acid substitutions D30N, E64Q, and N65D; and the IL-15Rα protein comprises SEQ ID NO:4.

[0037] In some embodiments, the first Fc domain comprises amino acid substitutions L368D and K370S; the second Fc domain comprises amino acid substitutions K246T, S364K, and E357Q; the first Fc domain and the second Fc domain each further comprise amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, M428L, and N434S according to EU numbering; the IL-15 protein comprises amino acid substitutions D30N, E64Q, and N65D; and the IL-15Rα protein comprises SEQ ID NO:4.

[0038] In some embodiments, the first Fc domain comprises amino acid substitutions S364K and E357Q; the second Fc domain comprises amino acid substitutions K246T, L368D, and K370; the first Fc domain and the second Fc domain each further comprise amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, M428L, and N434S according to EU numbering; the IL-15 protein comprises amino acid substitutions D30N, E64Q, and N65D; and the IL-15Rα protein comprises SEQ ID NO:4.

[0039] In some embodiments, the IL-15 protein is covalently linked to the N-terminus of the first Fc domain via a first linker. In some embodiments, the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain via a second linker. In some embodiments, the IL-15 protein is covalently linked to the N-terminus of the first Fc domain via a first linker and the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain via a second linker.

[0040] In some embodiments, the first linker and / or the second linker are independently a variable length Gly-Ser linker. In some embodiments, the second linker independently comprises a linker selected from the group consisting of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO:39), (Ser-Ser-Ser-Ser-Gly)n (SEQ ID NO:40), (Gly-Ser-Ser-Gly-Gly)n (SEQ ID NO:41), and (Gly-Gly-Ser-Gly-Gly)n (SEQ ID NO:42), where n is an integer from 1 to 5.

[0041] In some embodiments, the heterodimeric protein is selected from the group consisting of XENP22822, XENP23504, XENP24045, XENP24306, XENP22821, XENP23343, XENP23557, XENP24113, XENP24051, XENP24341, XENP24052, XENP24301, and XENP32803 proteins.

[0042] In some embodiments, the second monomer comprises the amino acid sequence set forth in SEQ ID NO:9 and the second monomer comprises the amino acid sequence set forth in SEQ ID NO:10. In some embodiments, the first monomer comprises the amino acid sequence set forth in SEQ ID NO:9 and the second monomer comprises the amino acid sequence set forth in SEQ ID NO:16.

[0043] In some embodiments, the heterodimeric protein is XENP24306, XENP32803, or a combination thereof.

[0044] In some embodiments, a combination of a first heterodimeric protein and a second heterodimeric protein is administered to a subject.In some embodiments, the first heterodimeric protein comprises a first monomer comprising the amino acid sequence shown in SEQ ID NO:9 and a second monomer comprising the amino acid sequence shown in SEQ ID NO:10, and the second heterodimeric protein comprises a first monomer comprising the amino acid sequence shown in SEQ ID NO:9 and a second monomer comprising the amino acid sequence shown in SEQ ID NO:16.

[0045] In some embodiments, the first heterodimeric protein and the second heterodimeric protein are administered simultaneously. In some embodiments, the first heterodimeric protein and the second heterodimeric protein are administered sequentially.

[0046] In some embodiments, the hematological cancer is selected from the group consisting of leukemia, acute myeloid leukemia, adult acute lymphoblastic leukemia, chronic lymphocytic leukemia, lymphoma, non-Hodgkin's lymphoma, B-cell non-Hodgkin's lymphoma, and multiple myeloma.

[0047] In some embodiments, the hematological cancer is multiple myeloma. In some embodiments, the multiple myeloma is relapsed or refractory multiple myeloma.

[0048] In some embodiments, the hematological cancer is B-cell non-Hodgkin's lymphoma.

[0049] In some embodiments, the hematological cancer is chronic lymphocytic leukemia.

[0050] In some embodiments, the subject has previously received one or more treatments. In some embodiments, the previous treatment is an immunomodulatory agent, a proteasome inhibitor, or an anti-CD38 monoclonal antibody. In some embodiments, the immunomodulatory agent is selected from the group consisting of lenalidomide, thalidomide, and pomalidomide. In some embodiments, the proteasome inhibitor is selected from the group consisting of bortezomib, carfilzomib, and ixazomib. In some embodiments, the anti-CD38 monoclonal antibody is selected from the group consisting of daratumumab, isatuximab, mezagitamab, and felzalutamab.

[0051] In some embodiments, the heterodimeric protein or combination of heterodimeric proteins is administered at a dose selected from the group consisting of about 0.0025 mg / kg, about 0.005 mg / kg, about 0.01 mg / kg, about 0.015 mg / kg, about 0.02 mg / kg, about 0.025 mg / kg, about 0.03 mg / kg, about 0.04 mg / kg, about 0.05 mg / kg, about 0.06 mg / kg, about 0.08 mg / kg, about 0.1 mg / kg, about 0.12 mg / kg, about 0.16 mg / kg, about 0.2 mg / kg, about 0.24 mg / kg, and about 0.32 mg / kg body weight.

[0052] In some embodiments, the heterodimeric protein or combination of heterodimeric proteins is administered at a dose selected from the group consisting of about 0.01 mg / kg, about 0.02 mg / kg, about 0.04 mg / kg, and about 0.06 mg / kg body weight.

[0053] In some embodiments, the heterodimeric protein or combination of heterodimeric proteins is administered at a dose selected from the group consisting of 0.0025 mg / kg, 0.005 mg / kg, 0.01 mg / kg, 0.015 mg / kg, 0.02 mg / kg, 0.025 mg / kg, 0.03 mg / kg, 0.04 mg / kg, 0.05 mg / kg, 0.06 mg / kg, 0.08 mg / kg, 0.10 mg / kg, 0.16 mg / kg, 0.20 mg / kg, 0.24 mg / kg, and 0.32 mg / kg body weight.

[0054] In some embodiments, the heterodimeric protein or combination of heterodimeric proteins is administered at a dose selected from the group consisting of 0.01 mg / kg, 0.02 mg / kg, 0.04 mg / kg, and 0.06 mg / kg body weight.

[0055] In some embodiments, the methods further comprise administering to the subject a CD38 binding antagonist.

[0056] In some embodiments, the anti-CD38 monoclonal antibody is selected from the group consisting of daratumumab, isatuximab, mezagitamab, and felzalutamab.

[0057] In some embodiments, the anti-CD38 monoclonal antibody is daratumumab.

[0058] In some embodiments, the heterodimeric protein and the anti-CD38 monoclonal antibody are administered simultaneously. In some embodiments, the heterodimeric protein and the anti-CD38 monoclonal antibody are administered sequentially.

[0059] In some embodiments, the heterodimeric protein is administered at a frequency selected from the group consisting of Q1W, Q2W, Q3W, Q4W, Q5W and Q6W. In some embodiments, the heterodimeric protein is administered at a frequency of Q1W for one or more cycles. In some embodiments, the heterodimeric protein is administered at a frequency of Q2W for one or more cycles. In some embodiments, the heterodimeric protein is administered at a frequency of Q4W for one or more cycles.

[0060] In some embodiments, the anti-CD38 monoclonal antibody is administered at a frequency selected from the group consisting of Q1W, Q2W, Q3W, Q4W, Q5W and Q6W. In some embodiments, the anti-CD38 monoclonal antibody is administered at a frequency of Q1W for one or more cycles. In some embodiments, the anti-CD38 monoclonal antibody is administered at a frequency of Q2W for one or more cycles. In some embodiments, the anti-CD38 monoclonal antibody is administered at a frequency of Q4W for one or more cycles.

[0061] In some embodiments, the heterodimeric protein is administered at a frequency of Q2W and the anti-CD38 monoclonal antibody is administered at a frequency of Q1W for one or more cycles. In some embodiments, the heterodimeric protein is administered at a frequency of Q2W and the anti-CD38 monoclonal antibody is administered at a frequency of Q2W for one or more cycles. In some embodiments, the heterodimeric protein is administered at a frequency of Q4W and the anti-CD38 monoclonal antibody is administered at a frequency of Q4W for one or more cycles.

[0062] In some embodiments, the heterodimeric protein is administered intravenously.

[0063] In some embodiments, the anti-CD38 antibody is administered subcutaneously. [Brief description of the drawings]

[0064] [Figure 1] Figures 1A and 1B show that the combination of XENP24306 (~82%) and XENP32803 (~18%) promotes dose-dependent proliferation of human NK cells (Figure 1A) and CD8+ T cells (Figure 1B) in human PBMCs. PBMCs from 22 individual human donors were treated with the indicated total concentration of the combination of XENP24306 (~82%) and XENP32803 (~18%) for 4 days, and the frequency of Ki67+ (a marker of cell proliferation) was measured by flow cytometry for CD3-CD56+ NK cells (Figure 1A) or CD3+CD8+CD16- T cells (Figure 1B). Each point represents the mean value of 22 donors, and error bars represent SEM. Curve fits were generated using least squares. EC50 values ​​were determined by nonlinear regression analysis with agonist versus response using a variable slope (four parameter) equation. [CD = cluster of differentiation; NK = natural killer; PBMC = peripheral blood mononuclear cells].

[0065] [Diagram 2]Figure 2 shows a comparison of CD8+ terminal effector T cell proliferation induced by the combination of XENP24306 (approximately 82%) and XENP32803 (approximately 18%), recombinant wild-type IL-15 (rIL15), and wild-type IL-15 / wild-type IL-15Rα heterodimeric Fc fusion (XENP22853) in human PBMCs [EC50 = half maximal effective concentration].

[0066] [Figure 3A-3D] Figures 3A-3D show graphs representing the absolute numbers of CD8β+ T cells (Figure 3A (male) and Figure 3B (female)) and NK cells (Figure 3C (male) and Figure 3D (female)) in whole blood of cynomolgus monkeys treated with repeated administration and various doses (0; 0.03 mg / kg; 0.2 mg / kg and 0.6 mg / kg) of the combination of XENP24306 (approximately 82%) and XENP32803 (approximately 18%). Whole blood from cynomolgus monkeys was stained with antibodies to identify CD8+ T cells as CD45+CD3+CD8β+CD4-CD16- and NK cells as CD45+CD3-CD16+. Each data point represents the mean value of 3-5 cynomolgus monkeys per group; error bars indicate SD.

[0067] [Figure 4] FIG. 4 is a graph depicting the serum concentration (ng / mL) versus time (days) profile of the mean (±SD) combination of heterodimeric proteins (XENP24306 (-82%) and XENP32803 (-18%)) in cynomolgus monkeys (males and females combined) following intravenous administration Q2W of a total of three doses of the heterodimeric proteins (0.03 mg / kg dose; 0.2 mg / kg and 0.6 mg / kg).

[0068] [Diagram 5]FIG. 5 is a schematic diagram of a combination study of IL15 / IL15Rα heterodimeric protein (e.g., XENP24306, XENP32803, or a combination of XENP24306 (about 82%) and XENP32803 (about 18%)) and daratumumab, showing subjects enrolled in two phases, the dose escalation phase and the expansion phase, and details of these two phases. DL = dose level; DLT = dose-limiting toxicity; MAb = monoclonal antibody; MAD = maximum dose; MTD = maximum tolerated dose; RP2D = recommended phase II dose; SC = subcutaneous; TBD = to be determined. a Based on the accumulation of safety data in this study, alternative IL15 / IL15Rα dosing schedules may be considered. b See FIG. 6 for dosing schedule of daratumumab SC. cSafety threshold is defined as a DLT in one subject not attributable to another clearly identifiable cause or a major organ adverse event of grade >2 in at least two subjects during the DLT assessment window in a given cohort.

[0069] [Figure 6] FIG. 6 is a study schema for combination therapy of IL15 / IL15Rα heterodimeric proteins (e.g., XENP24306, XENP32803, or a combination of XENP24306 (about 82%) and XENP32803 (about 18%) in combination with daratumumab (anti-CD38 antibody), showing the dosing schedule. SC=subcutaneous; IV=intravenous; TBD=to be determined; C=cycle; Q1W=weekly; Q2W=every 2 weeks; Q4W=every 4 weeks; wk=weekly. Subjects may continue to receive treatment with IL15 / IL15Rα until they meet criteria for discontinuation of study treatment, discontinue the study, or the study is terminated by the study provider.

[0070] [Figure 7]Figure 7 provides the amino acid sequences of XENP24306 monomer 1 (SEQ ID NO: 9), XENP24306 monomer 2 (SEQ ID NO: 10), XENP32803 monomer 1 (SEQ ID NO: 9) and XENP32803 monomer 2 (SEQ ID NO: 16). In the sequence of monomer 1, the IL15 portion is underlined and the linker is offset by a slash and is shown in bold and underlined. The Fc portion is after the second slash and does not contain any formatting. In the sequence of monomer 2, the IL15Rα portion is underlined and the linker is offset by a slash and is shown in bold and underlined. The Fc portion is after the second slash and does not contain any formatting.

[0071] [Figure 8A-8B] Figures 8A and 8B provide the amino acid sequences for human IL-15 precursor protein (full-length human IL-15) (SEQ ID NO:2), mature or truncated human IL-15 protein (SEQ ID NO:1), full-length human IL-15Rα protein (SEQ ID NO:3), the extracellular domain of human IL-15Rα protein (SEQ ID NO:54), the sushi domain of human IL-15Rα protein (SEQ ID NO:4), full-length human IL-15Rβ protein (SEQ ID NO:55) and the extracellular domain of human IL-15Rβ protein (SEQ ID NO:56).

[0072] [Figures 9A-9G]9A-9G show the first monomer of XENP22853 wild-type IL-15-Fcw (SEQ ID NO: 11), the XENP22822 protein (SEQ ID NO: 19 and SEQ ID NO: 20), the XENP23504 protein (SEQ ID NO: 29 and SEQ ID NO: 30), the XENP24045 protein (SEQ ID NO: 23 and SEQ ID NO: 24), the XENP22821 protein (SEQ ID NO: 17 and SEQ ID NO: 18), the XENP23343 protein (SEQ ID NO: 31 and SEQ ID NO: 32 ... Amino acid sequences are provided for the NP23557 protein (SEQ ID NO:21 and SEQ ID NO:22), the XENP24113 protein (SEQ ID NO:33 and SEQ ID NO:34), the XENP24051 protein (SEQ ID NO:25 and SEQ ID NO:26), the XENP24341 protein (SEQ ID NO:35 and SEQ ID NO:36), the XENP24052 protein (SEQ ID NO:27 and SEQ ID NO:28), and the XENP24301 protein (SEQ ID NO:37 and SEQ ID NO:38). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0073] Detailed Description overview The practice of the methods described herein and the preparation and use of the compositions will employ common techniques within the skill of the art in molecular biology, biochemistry, chromatin structure and analysis, computational chemistry, cell culture, recombinant DNA and related fields, unless otherwise indicated. These techniques are fully described in the literature. See, for example, Sambrook et al., MOLECULAR CLONING: A LABORATORY MANUAL, 4th ed., Cold Spring Harbor Laboratory Press, 2012; Ausubel et al., CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, John Wiley and Sons, New York, 1987-2010 and regularly updated.

[0074] The term "herein" means the entire specification.

[0075] It should be understood that any of the embodiments described herein, including those described in different aspects of the disclosure and in different parts of the specification (including embodiments described only in the examples), can be combined with one or more of the other embodiments described herein, unless expressly stated to the contrary or inappropriate. Combinations of embodiments are not limited to the specific combinations claimed by multiple dependent claims.

[0076] Any publications, patents, and published patent applications mentioned herein are specifically incorporated herein by reference. In case of conflict, the present specification, including its specific definitions, will control.

[0077] Throughout this specification, the word "comprise" or variations such as "comprises" or "comprising" are synonymous with "including," "containing," or "characterized by," and are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0078] Throughout this specification, when a composition is described as having, including, or comprising a particular component (or variations thereof), it is considered that the composition may consist essentially of or consist of the recited component. Similarly, when a method or process is described as having, including, or comprising a particular process step, the process may consist essentially of or consist of the recited process step. Furthermore, it should be understood that the order of steps or order of performing certain actions is not important so long as the compositions and methods described herein are operable. Moreover, two or more steps or actions may be performed simultaneously.

[0079] The term "consisting of" excludes any element, step, or ingredient not specifically recited.

[0080] The term "consisting essentially of" limits the scope of the disclosure to the specified materials or steps, and those that do not materially affect the basic and novel characteristics of the disclosure.

[0081] The term "for example" followed by one or more examples is not meant to be exclusive or limiting.

[0082] The articles "a" and "an" are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, "element" means one element or more than one element.

[0083] As used herein, the term "about" modifies the quantity of a composition component, parameter, calculation, or measurement used in the disclosed method, for example, by common measuring and liquid handling procedures used to make isolated polypeptides or pharmaceutical compositions in the real world; by inadvertent errors in these procedures; by differences in the manufacture, source, or purity of the components used to make the composition or carry out the method; and the like, without substantially affecting the chemical or physical attributes of the disclosed composition or method. Such variations may typically be within 10% of a given value or range, more typically even within 5%. The term "about" also encompasses amounts that vary due to different equilibrium conditions of the composition resulting from a particular initial mixture. Whether modified by the term "about," a paragraph includes its equivalent of the quantity. Reference herein to a value or parameter followed by "about" includes (and describes) embodiments that are directed to the value or parameter itself. For example, a statement that refers to "about X" includes the statement "X." A numerical range includes the numerical values ​​defining the range.

[0084] As used herein, the term "or" should be understood to mean "and / or" unless the context clearly indicates otherwise.

[0085] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the present disclosure are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges described herein should be understood to encompass all subranges contained therein. For example, a range described as "1 to 10" should be considered to include all subranges between a minimum value of 1 and a maximum value of 10, inclusive; i.e., all subranges beginning with a minimum value equal to or greater than 1, e.g., 1 to 6.1, and all subranges ending with a maximum value equal to or less than 10, e.g., 5.5 to 10. The disclosure of a range should also be considered as a disclosure of the endpoints of that range.

[0086] Exemplary methods and materials are described below, although methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present application. The materials, methods, and examples are illustrative only and not intended to be limiting.

[0087] definition The following terms, unless otherwise indicated, shall be understood to have the following meanings:

[0088] As used herein, the term "ablation" refers to the reduction or elimination of activity. Thus, for example, "ablation of FcγR binding" means that the Fc region amino acid variant has less than 50% of the starting binding compared to the Fc region that does not contain the specific variant, with less than 70%, 80%, 90%, 95% or 98% of the activity loss being preferred, and generally the activity is below the level of binding detectable in BIACORE® assay (Pharmacia Biosensor AB, Uppsala, Sweden and Piscataway, NJ). Unless otherwise specified, the Fc domain described herein retains binding to the FcRn receptor.

[0089] "Administering" a substance, compound or agent to a subject, or "administration of" a substance, compound or agent to a subject, refers to contacting the substance, compound or agent with the subject or with the subject's cells, tissues, organs or bodily fluids. Such administration may be performed using one of a variety of methods known to those skilled in the art. For example, the compound or agent may be administered intravenously or subcutaneously. Administration may also be performed, for example, once, multiple times, and / or over one or more extended periods of time. In some embodiments, administration includes both direct administration, including self-administration, and indirect administration, including the act of prescribing a drug. For example, as used herein, a physician who instructs a subject to self-administer a drug or to have another person administer a drug, and / or provides a subject with a prescription for a drug, is administering a drug to a subject.

[0090] As used herein, the term "affinity" of a molecule refers to the strength of interaction between the molecule and a binding partner, such as a receptor, ligand, or antigen. The affinity of a molecule for its binding partner is typically measured by the binding affinity equilibrium dissociation constant (K D ) and K D The lower the K, the higher the affinity. D The binding affinity constant can be measured by surface plasmon resonance, for example, using the BIACORE® system (Pharmacia Biosensor AB, Uppsala, Sweden, and Pistacawe, NJ).See also Jonsson et al., Ann.Biol.Clin.51:19 26 (1993); Jonsson et al., Biotechniques 11:620 627 (1991); Jonsson et al., J.Mol.Recognit.8:125 131 (1995); Johnsson et al., Anal.Biochem.198:268 277 (1991); Hearty S et al., Methods Mol Biol.907:411-42 (2012), each of which is incorporated herein by reference. Dmay be measured using a KinExA® system (Sapidyne Instruments, Hannover, Germany, and Boise, ID). In some embodiments, the IL-15 variants of the heterodimeric proteins described herein have reduced binding affinity to the IL-2 / IL-15βγ receptor compared to wild-type IL-15. In some embodiments, the first and / or second Fc variants of the heterodimeric proteins described herein have reduced affinity to human, cynomolgus monkey, and mouse Fcγ receptors. In some embodiments, the first and / or second Fc variants of the heterodimeric proteins described herein do not bind to human, cynomolgus monkey, and mouse Fcγ receptors.

[0091] As used herein, the terms "amino acid" and "amino acid identity" refer to one of the 20 naturally occurring amino acids encoded by DNA and RNA.

[0092] As used herein, the term "amino acid substitution" or "substitution" refers to the replacement of an amino acid at a particular position of a parent polypeptide sequence with a different amino acid. In particular, in some embodiments, the substitution is for an amino acid that does not naturally occur at the particular position and does not naturally occur in the organism or in any organism. For example, the substitution E272Y refers to a variant polypeptide, in this case an Fc variant, in which glutamic acid at position 272 is replaced with tyrosine. For clarity, a protein that has been engineered to change the nucleic acid coding sequence but not change the starting amino acid (e.g., replacing CGG (which codes for arginine) with CGA (which still codes for arginine) to increase the expression level of the host organism) is not an "amino acid substitution". That is, if a new gene is generated that codes for the same protein, but the protein has the same amino acid at the particular position that is the starting position, it is not considered an amino acid substitution.

[0093] As used herein, the term "amino acid insertion", "amino acid addition" or "addition" or "insertion" refers to the addition of an amino acid sequence at a particular position of a parent polypeptide sequence. For example, -233E, _233E or 233E indicates the insertion of a glutamic acid after position 233 and before position 234. Additionally, -233ADE, _233ADE or 233ADE indicates the insertion of AlaAspGlu after position 233 and before position 234.

[0094] As used herein, the term "amino acid deletion" or "deletion" refers to the removal of an amino acid sequence at a particular position in a parent polypeptide sequence. For example, E233- or E233#, E233(), E233_ or E233del indicates the deletion of glutamic acid at position 233. Additionally, EDA233-, EDA233_ or EDA233# indicates the deletion of the sequence GluAspAla beginning at position 233.

[0095] As used herein, the term "antibody" or "Ab" refers to an immunoglobulin molecule (e.g., a complete antibody, an antibody fragment, or a modified antibody) that can recognize and bind to a specific target or antigen, such as a carbohydrate, a polynucleotide, a lipid, a polypeptide, etc., located in the variable region of the immunoglobulin molecule through at least one antigen recognition site. As used herein, the term "antibody" can include any type of antibody, including, but not limited to, monoclonal antibodies, polyclonal antibodies, human antibodies, engineered antibodies (including humanized antibodies, fully human antibodies, chimeric antibodies, single chain antibodies, artificially selected antibodies, CDR-granulated antibodies, etc.) that specifically bind to a given antigen. In some embodiments, "antibody" and / or "immunoglobulin" (Ig) refers to a polypeptide that includes at least two heavy (H) chains (about 50-70 kDa) and two light (L) chains (about 25 kDa), optionally interconnected by disulfide bonds. There are two types of light chains: lambda and kappa. In humans, lambda and kappa light chains are similar, but only one type exists in each antibody. Heavy chains are classified as mu, delta, gamma, alpha, or epsilon, and define the antibody's isotype as IgM, IgD, IgG, IgA, and IgE, respectively. For a review, see Fundamental Immunology Ch. 7 (Paul, W., ed., 2nd ed. Raven Press, NY (1989)), which is incorporated by reference in its entirety. The methods, uses, and compositions for use described herein utilize IgG antibodies.

[0096] As used herein, the term "checkpoint inhibitor" refers to a compound that targets and blocks checkpoint proteins. Checkpoint inhibitors interfere with the interaction between checkpoint proteins and their partner proteins. Examples of checkpoint inhibitors include, but are not limited to, agents that target the PD-1 / PD-L1 axis and agents that target CTLA-4.

[0097] As used herein, the term "cycle" refers to each dosing event in a series of dosing steps that are repeated periodically. For example, if a therapeutic agent (e.g., a heterodimeric protein of the present disclosure) is administered once every two weeks (Q2W), the first cycle begins on day 1 and ends on day 14, the second cycle begins on day 15 and ends on day 28, the third cycle begins on day 29 and ends on day 42, etc. Measurements may be taken and combination therapy administered mid-cycle. Events mid-cycle may be defined by the cycle and the day of the cycle on which they occur, e.g., measurements taken in a one- to two-week cycle may be numbered cycle 1, day 8 (or C1D8). In the case of combination therapy, a cycle is defined by the period it takes for the dosing pattern to be repeated. For example, if a first therapeutic agent is administered Q2W and a second therapeutic agent is administered Q1W, the cycle is a two-week cycle. In such a case, if both agents are administered on C1D1, the second dose of the second agent is administered on C1D8, and the second dose of the first agent in combination with the third dose of the second agent is administered one week later to begin the second cycle (i.e., C2D1). If the first agent is administered Q1W and the second agent is administered every three days (Q3D), it takes three weeks for the dosing pattern to repeat, so the cycle is a three week cycle, including three doses of the first agent and seven doses of the second agent.

[0098] As used herein, the term "effector function" refers to a biochemical event resulting from the interaction of the Fc region of an antibody with an Fc receptor or another effector molecule (e.g., Fc receptor-like (FcRL) molecule, complement component C1q, and tripartite motif-containing protein 21 (TRIM21)). Effector functions include, but are not limited to, antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cell-mediated phagocytosis (ADCP), and complement-dependent cytotoxicity (CDC). As used herein, the term "ADCC" or "antibody-dependent cell-mediated cytotoxicity" refers to a cell-mediated reaction in which non-specific cytotoxic cells expressing FcγR recognize bound antibody on a target cell, subsequently causing lysis of the target cell. ADCC correlates with binding to FcγRIIIa, and increased binding to FcγRIIIa results in increased ADCC activity. As discussed herein, many embodiments of the present disclosure completely ablate ADCC activity. As used herein, the term "ADCP" or antibody-dependent cell-mediated phagocytosis" refers to a cell-mediated reaction in which non-specific cytotoxic cells expressing FcγR recognize bound antibodies on target cells and subsequently cause phagocytosis of the target cells. As used herein, the term "CDC" or "complement-dependent cytotoxicity" refers to an effector function that results in activation of the classical complement pathway, which is triggered by the binding of antibodies to antigens on target cells and activates a series of cascades involving complement-related proteins in the blood.

[0099] As used herein, the terms "Fc", "Fc region" or "Fc domain" are used interchangeably herein and refer to a polypeptide comprising the constant region of an antibody, in some cases excluding the first constant region immunoglobulin domain (e.g., CH1) or a portion thereof, and in some cases to a portion of the hinge. In the case of IgG, the Fc domain comprises immunoglobulin domains Cγ2 and Cγ3 (Cγ2 and Cγ3) and the lower hinge region between Cγ1 (Cγ1) and Cγ2 (Cγ2). In some embodiments, Fc refers to the truncated CH1 domain and CH2 and CH3 of an immunoglobulin. Although the boundaries of the Fc region can vary, the human IgG heavy chain Fc region is usually defined to include residues E216 or C226 or P230 at its carboxyl terminus, with numbering according to EU numbering. In some embodiments, amino acid modifications are made to the Fc region, e.g., to alter binding to one or more FcγR or FcRn receptors, as described in more detail herein. In some embodiments, the Fc domain is derived from a human IgG1 heavy chain Fc domain. In some embodiments, the Fc domain is derived from a human IgG2 heavy chain Fc domain. "EU format as defined by Edelman" or "EU numbering" or "EU index" refers to the numbering of residues in a human Fc domain as described in Edelman GM et al. (Proc. Natl. Acad. USA (1969), 63, 78-85, which is incorporated herein by reference in its entirety).

[0100] As used herein, the terms "Fc fusion protein" and "immunoadhesin" are used interchangeably and generally refer to a protein comprising an Fc region linked (optionally through a linker moiety as described herein) to a different protein as described herein, e.g., IL-15 and / or IL-15R. In some instances, two Fc fusion proteins may form a homodimeric Fc fusion protein or a heterodimeric Fc fusion protein, the latter being preferred.

[0101] As used herein, the term "Fc variant" or "variant Fc" refers to a protein that contains an amino acid modification in the Fc domain. The Fc variants of the present invention are defined according to the amino acid modifications that compose them. Thus, for example, N434S is an Fc variant that has a substitution serine at position 434 relative to the parent Fc polypeptide, with numbering according to the EU index. Similarly, M428L / N434S defines an Fc variant that has substitutions M428L and N434S compared to the parent Fc polypeptide. For all positions discussed in the present invention related to antibodies, unless otherwise stated, the numbering of the amino acid positions is according to the EU index. The modification can be an addition, deletion, or substitution. The substitution can include naturally occurring amino acids, and in some cases synthetic amino acids. Examples include, but are not limited to, U.S. Patent No. 6,586,207; WO 98 / 48032; WO 03 / 073238; U.S. Patent Application Publication No. 2004-0214988; WO 05 / 35727A2; WO 05 / 74524A2; JW Hin et al. (2002), Journal of the American Chemical Society 124:9026-9027; JW Hin, and PGSchultz, (2002), ChemBioChem 11:1135-1137; JW Hin, et al. (2002), PICAS United States of America 99:11020-11024; and L. Wang, and PGSchultz, (2002), Chem. 1-10, all of which are incorporated by reference in their entireties. In some embodiments, the substitutions include only naturally occurring amino acids, hi some embodiments, the substitutions do not include synthetic amino acids.

[0102] As used herein, the terms "Fc gamma receptor", "FcγR" and "Fc gamma R" are used interchangeably and refer to any member of a family of proteins that bind to the Fc region of IgG antibodies and are encoded by FcγR genes. FcγR can be from any organism. In some embodiments, FcγR is a human FcγR. In humans, this family includes, but is not limited to, FcγRI (CD64), which includes isoforms FcγRIa, FcγRIb, and FcγRIc; FcγRII (CD32), which includes isoforms FcγRIIa (including allotypes H131 and R131), FcγRIIb (including FcγRIIb-1 and FcγRIIb-2), and FcγRIIc; FcγRIII (CD16), which includes isoforms FcγRIIIa (including allotypes V158 and F158) and FcγRIIIb (including allotypes FcγRIIb-NA1 and FcγRIIb-NA2) (Jefferis et al., 2002, Immunol Lett 82:57-65 (incorporated by reference in its entirety)), and any undiscovered human FcγR or FcγR isoforms or allotypes.

[0103] As used herein, "FcRn" or "neonatal Fc receptor" refers to a protein that binds to an IgG antibody Fc region and is at least partially encoded by the FcRn gene. The FcRn may be from any organism. In some embodiments, the FcRn is human FcRn. As known in the art, a functional FcRn protein comprises two polypeptides, often referred to as heavy and light chains. The light chain is beta2 microglobulin, and the heavy chain is encoded by the FcRn gene. Unless otherwise specified herein, FcRn or FcRn protein refers to the complex of the FcRn heavy chain and beta2 microglobulin. Various FcRn variants may be used to increase binding to the FcRn receptor and in some cases increase serum half-life. In general, unless otherwise specified, the Fc monomers described herein retain binding to the FcRn receptor (and may include amino acid variants that increase binding to the FcRn receptor, as described below).

[0104] As used herein, the term "modification" refers to amino acid substitution, insertion, and / or deletion in a polypeptide sequence or modification to a moiety that is chemically bound to a protein. For example, the modification can be a modified carbohydrate or PEG structure that is bound to a protein. As used herein, "amino acid modification" refers to amino acid substitution, insertion, and / or deletion in a polypeptide sequence. For clarity, unless otherwise specified, amino acid modification always refers to amino acids that are coded by DNA, such as the 20 amino acids that have codons in DNA and RNA.

[0105] The terms "nucleic acid", "polynucleotide" and "oligonucleotide" are used interchangeably and refer to deoxyribonucleotide or ribonucleotide polymers in linear or circular conformation and in single- or double-stranded form. For the purposes of this disclosure, these terms are not to be construed as limiting on the length of the polymer. These terms can encompass known analogs of natural nucleotides as well as nucleotides modified at the base, sugar and / or phosphate moieties (e.g., phosphorothioate backbones). In general, an analog of a particular nucleotide has the same base-pairing specificity; i.e., an analog of A will base pair with T. In some embodiments, a polynucleotide comprises only natural nucleotides. In some embodiments, a polynucleotide does not comprise any analogs of natural nucleotides.

[0106] As used herein, the term "non-naturally occurring modification" refers to a non-isotypic amino acid modification. For example, the substitution 434S in IgG1, IgG2, IgG3, or IgG4 (or hybrids thereof) is considered a non-naturally occurring modification, since none of the IgGs contain serine at position 434.

[0107] The terms "patient," "subject," and "individual" are used interchangeably herein and refer to a human or non-human animal in need of treatment. These terms include mammals, such as humans, and primates (e.g., monkeys). In some embodiments, the subject is a human. In some embodiments, the subject is in need of treatment for a hematological cancer, such as multiple myeloma. As used herein, "treating" and "treatment" refer to reducing the severity and / or frequency of symptoms, eliminating symptoms and / or their causes, preventing the onset of symptoms and / or their causes, and ameliorating or repairing damage.

[0108] As used herein, "percent amino acid sequence identity" with respect to a protein sequence is defined as the percentage of amino acid residues in a candidate sequence that are identical to amino acid residues in a particular (parent) sequence, without considering any conservative substitutions as part of the sequence identity, after aligning the sequences and introducing gaps as necessary to obtain the maximum percent sequence identity. Alignment for purposes of determining percent amino acid sequence identity can be accomplished in a variety of ways that are within the skill of the art, for example, using publicly available computer software such as BLAST, BLAST-2, ALIGN, or Megalign (DNASTAR) software. Those skilled in the art can determine appropriate parameters for measuring alignment, including any algorithms necessary to achieve maximum alignment over the full length of the sequences being compared. One particular program is the ALIGN-2 program, as outlined in paragraphs

[0279] to

[0280] of U.S. Patent Application Publication No. 20160244525, which is incorporated herein by reference.

[0109] As used herein, the terms "polypeptide", "peptide" and "protein" are used interchangeably and refer to a polymer of amino acid residues. The term also applies to amino acid polymers in which one or more amino acids are chemical analogs or modified derivatives of the corresponding naturally occurring amino acids. In some embodiments, a polypeptide contains only naturally occurring amino acids. In some embodiments, a polypeptide does not contain chemical analogs or modified derivatives of the corresponding naturally occurring amino acids. Expression of a fusion protein in a cell can result from delivery of a fusion protein to a cell or from delivery of a polynucleotide encoding the fusion protein to a cell, where the polynucleotide is transcribed and the transcript is translated to produce the fusion protein. Trans-splicing, polypeptide cleavage and polypeptide ligation may also be involved in the expression of a protein in a cell. Methods for polynucleotide and polypeptide delivery to a cell are known in the art.

[0110] As used herein, the term "position" refers to a position in a protein sequence. Positions may be numbered consecutively or according to established formats, such as the EU index for antibody numbering. Positions may be defined relative to a reference sequence. In such cases, a reference sequence is provided for comparison purposes, and the heterodimeric protein of the present disclosure (or a portion thereof) may include additional amino acid changes (e.g., substitutions, insertions, and deletions) relative to the reference sequence. In some embodiments, the heterodimeric protein of the present disclosure (or a portion thereof) does not include any additional amino acid changes relative to the reference sequence.

[0111] As used herein, the term "residue" refers to a position in a protein and its associated amino acid identity. For example, asparagine 297 (also called Asn297 or N297) is the residue at position 297 in a particular protein.

[0112] As used herein, the terms "therapeutically effective amount" and "effective amount" are used interchangeably herein and refer to an amount of a therapeutic agent administered as a single agent or in combination with one or more additional agents that relieves to some extent one or more symptoms of the condition being treated. In some embodiments, a therapeutically effective amount is an amount sufficient to produce an effective or desired clinical result. In the context of cancer treatment, a therapeutically effective amount refers to an amount that has at least one of the effects of palliating, ameliorating, stabilizing, reversing, preventing, slowing, or delaying the progression of (and / or symptoms associated with) hematological cancer, such as multiple myeloma. Effective amounts that can be used in the present disclosure vary depending on the mode of administration, the age, weight, and general health of the subject. Appropriate amounts and dosing regimens can be determined using routine skill in the art. For example, efficacy can be determined using the International Myeloma Working Group (IMWG) Uniform Response Criteria.

[0113] The terms "wild type" or "WT" are used interchangeably herein and refer to an amino acid sequence or nucleotide sequence found in nature, including allelic variants. A WT protein has an amino acid sequence that has not been intentionally modified or is encoded by a nucleotide sequence that has not been intentionally modified.

[0114] overview The present disclosure relates to a method of treating hematological cancer in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a heterodimeric protein (or a combination of heterodimeric Fc fusion proteins) comprising IL-15 and IL-15 receptor alpha (IL-15Rα) protein domains. + A method for inducing the proliferation of effector memory T cells and / or NK cells or for inducing IFNγ production in a subject suffering from a hematological cancer, comprising administering to the subject an effective amount of a heterodimeric protein (or a combination of heterodimeric Fc fusion proteins) comprising IL-15 and IL-15 receptor alpha (IL-15Rα) protein domains. The Fc domain can be derived from an IgG Fc domain, e.g., an IgG1, IgG2, IgG3 or IgG4 Fc domain.

[0115] IL15-IL15Rα heterodimeric Fc fusion protein Any of the IL15-IL15Rα heterodimeric Fc fusion proteins disclosed in US Patent Application Publication No. 2018 / 0118805, the entire disclosure of which is incorporated herein by reference, or combinations thereof, may be used in the methods described herein. These include, among others, Fc variants, such as conformational variants (e.g., "knob-into-holes," "skew," "electro static steering," "charged pair" variants), pI variants, isotype variants, FcγR variants and ablation variants (e.g., "FcγR ablation variants" or "Fc knockout (FcKO or KO)" variants), as well as the various IL-15 and IL15Rα proteins disclosed therein.

[0116] Thus, in some embodiments, a heterodimeric protein useful in the methods described herein comprises (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain, and (ii) a second monomer comprising an IL-15Rα protein and a second Fc domain, wherein the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain; the first Fc domain and the second Fc domain are, respectively, S267K / L368D / K370S:S267K / S364K / E357Q;S364K / E35 7Q:L368D / K370S;L368D / K370S:S364K;L368E / K370S:S364K;T411E / K360E / Q362E:D401K;L3 68D / K370S:S364K / E357L;K370S:S364K / E357Q;S267K / S364K / E357Q:S267K / L368D / K370S;{ 1>L368D / K370S:S364K / E357Q; S364K:L368D / K370S; S364K:L368E / K370S; D401K:T411E / K360E / Q362E; S364K / E357L:L368D / K370S; and S364K / E357Q:K370S.

[0117] In some embodiments, the first Fc domain and the second Fc domain each comprise a set of amino acid substitutions of S267K / L368D / K370S:S267K / S364K / E357Q according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each comprise a set of amino acid substitutions of S364K / E357Q:L368D / K370S according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each comprise a set of amino acid substitutions of L368D / K370S:S364K according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each comprise a set of amino acid substitutions of L368E / K370S:S364K according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each comprise a set of amino acid substitutions of T411E / K360E / Q362E:D401K according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each comprise a set of amino acid substitutions of L368D / K370S:S364K / E357L according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each comprise a set of amino acid substitutions of K370S:S364K / E357Q according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each comprise a set of amino acid substitutions of S267K / S364K / E357Q:S267K / L368D / K370S according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each comprise a set of amino acid substitutions of L368D / K370S:S364K / E357Q according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each comprise a set of amino acid substitutions of S364K:L368D / K370S according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each comprise a set of amino acid substitutions of S364K:L368E / K370S according to EU numbering.In some embodiments, the first Fc domain and the second Fc domain each comprise a set of amino acid substitutions of D401K:T411E / K360E / Q362E according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each comprise a set of amino acid substitutions of S364K / E357L:L368D / K370S according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each comprise a set of amino acid substitutions of S364K / E357Q:K370S according to EU numbering.

[0118] In some embodiments, each of the first Fc domain and / or the second Fc domain independently further comprises an amino acid substitution selected from the group consisting of Q295E, N384D, Q418E and N421D according to EU numbering, or a combination thereof. In some embodiments, the first Fc domain further comprises an amino acid substitution selected from the group consisting of Q295E, N384D, Q418E and N421D according to EU numbering, or a combination thereof. In some embodiments, the second Fc domain further comprises an amino acid substitution selected from the group consisting of Q295E, N384D, Q418E and N421D according to EU numbering, or a combination thereof. In some embodiments, each of the first Fc domain and the second Fc domain further comprises an amino acid substitution selected from the group consisting of Q295E, N384D, Q418E and N421D according to EU numbering, or a combination thereof. In some embodiments, the first Fc domain further comprises amino acid substitutions Q295E, N384D, Q418E, and N421D according to EU numbering. In some embodiments, the second Fc domain further comprises amino acid substitutions Q295E, N384D, Q418E, and N421D according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each further comprise amino acid substitutions Q295E, N384D, Q418E, and N421D according to EU numbering.

[0119] In some embodiments, the first Fc domain does not contain a free cysteine ​​at position 220 according to EU numbering. In some embodiments, the first Fc domain contains the amino acid substitution C220S according to EU numbering. In some embodiments, the second Fc domain does not contain a free cysteine ​​at position 220 according to EU numbering. In some embodiments, the second Fc domain contains the amino acid substitution C220S according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain do not contain a free cysteine ​​at position 220 according to EU numbering. In some embodiments, both the first Fc domain and the second Fc domain contain the amino acid substitution C220S according to EU numbering.

[0120] In some embodiments, the first Fc domain further comprises one or more amino acid substitutions selected from the group consisting of E233P, L234V, L235A, G236del, G236R, S239K, S267K, A327G and L328R, or a combination thereof, according to EU numbering. In some embodiments, the first Fc domain further comprises amino acid substitutions E233P, L234V, L235A, G236del, and S267K, according to EU numbering. In some embodiments, the second Fc domain further comprises one or more amino acid substitutions selected from the group consisting of E233P, L234V, L235A, G236del, G236R, S239K, S267K, A327G and L328R, or a combination thereof, according to EU numbering. In some embodiments, the second Fc domain further comprises the amino acid substitutions E233P, L234V, L235A, G236del, and S267K according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each comprise the amino acid substitutions E233P, L234V, L235A, G236del, and S267K according to EU numbering.

[0121] The positions of the various Fc domain substitutions are based on the corresponding positions in the wild-type IgG1 Fc domain (SEQ ID NO: 12). The amino acid sequence of the wild-type IgG1 Fc domain (SEQ ID NO: 12) is an exemplary sequence provided for comparison purposes, and the Fc domain of the heterodimeric protein may include additional amino acid changes (e.g., substitutions, insertions, and deletions) relative to the wild-type IgG1 Fc domain (SEQ ID NO: 12). For example, the Fc domain of the heterodimeric protein may be derived from a different wild-type human IgG1 allele. In some embodiments, the Fc domain of the heterodimeric protein does not include any additional amino acid changes relative to the wild-type IgG1 Fc domain (SEQ ID NO: 12). A person skilled in the art would be able to determine the corresponding substitutions in an Fc domain derived from an IgG2, IgG3, or IgG4 Fc domain. For example, a person skilled in the art would know that residues E233, L234, L235, and G236 are present in an Fc domain derived from an IgG1 or IgG3 Fc domain. In some embodiments, the positions of the various Fc domain substitutions are based on the corresponding positions in the Fc domain of wild-type IgG3 (SEQ ID NO: 14). The amino acid sequence of the Fc domain of wild-type IgG3 (SEQ ID NO: 14) is an exemplary sequence provided for comparison purposes, and the Fc domain of the heterodimeric protein may include additional amino acid changes (e.g., substitutions, insertions, and deletions) relative to the Fc domain of wild-type IgG3 (SEQ ID NO: 14). For example, the Fc domain of the heterodimeric protein may be derived from a different wild-type human IgG3 allele. In some embodiments, the Fc domain of the heterodimeric protein does not include any additional amino acid changes compared to the Fc domain of wild-type IgG3 (SEQ ID NO: 14).

[0122] In some embodiments, each of the first Fc domain and / or the second Fc domain independently further comprises an amino acid substitution selected from the group consisting of: G236R / L328R; E233P / L234V / L235A / G236del / S239K; E233P / L234V / L235A / G236del / S267K; E233P / L234V / L235A / G236del / S239K / A327G; E233P / L234V / L235A / G236del / S267K / A327G; and E233P / L234V / L235A / G236del, according to EU numbering, and wherein the Fc domain is derived from an IgG1 or IgG3 Fc domain. In some embodiments, the first Fc domain further comprises an amino acid substitution selected from the group consisting of: G236R / L328R; E233P / L234V / L235A / G236del / S239K; E233P / L234V / L235A / G236del / S267K; E233P / L234V / L235A / G236del / S239K / A327G; E233P / L234V / L235A / G236del / S267K / A327G; and E233P / L234V / L235A / G236del, according to EU numbering, and wherein the Fc domain is derived from an IgG1 or IgG3 Fc domain. In some embodiments, the second Fc domain further comprises an amino acid substitution selected from the group consisting of: G236R / L328R; E233P / L234V / L235A / G236del / S239K; E233P / L234V / L235A / G236del / S267K; E233P / L234V / L235A / G236del / S239K / A327G; E233P / L234V / L235A / G236del / S267K / A327G; and E233P / L234V / L235A / G236del, according to EU numbering, and wherein the Fc domain is derived from an IgG1 or IgG3 Fc domain.In some embodiments, the first Fc domain and the second Fc domain further comprise an amino acid substitution selected from the group consisting of: G236R / L328R; E233P / L234V / L235A / G236del / S239K; E233P / L234V / L235A / G236del / S267K; E233P / L234V / L235A / G236del / S239K / A327G; E233P / L234V / L235A / G236del / S267K / A327G; and E233P / L234V / L235A / G236del (according to EU numbering), wherein the Fc domain is derived from an IgG1 or IgG3 Fc domain.

[0123] Those skilled in the art will also understand that the corresponding residues in the Fc domain derived from the Fc domain of IgG2 are P233, V234, and A235, and that the Fc domain derived from IgG2 lacks a residue corresponding to residue G236. Thus, those skilled in the art will understand that when the Fc domain is an IgG2 Fc domain (i.e., the PVA-sequence present in wild-type IgG2), references herein to E233P, L234V, L235A, and G236del are references to P233, V234, A235, and -236. In some embodiments, the positions of the various Fc domain substitutions are relative to the corresponding positions in the wild-type IgG2 Fc domain (SEQ ID NO: 13). The amino acid sequence of the wild-type IgG2 Fc domain (SEQ ID NO: 13) is an exemplary sequence provided for comparison purposes, and the Fc portion of the heterodimeric protein may include additional amino acid changes (e.g., substitutions, insertions, and deletions) relative to the wild-type IgG2 Fc domain (SEQ ID NO: 13). For example, the Fc domain of the heterodimeric protein may be derived from various wild-type human IgG2 alleles. In some embodiments, the Fc domain of the heterodimeric protein does not contain any additional amino acid changes compared to the wild-type IgG2 Fc domain (SEQ ID NO: 13).

[0124] In some embodiments, each of the first Fc domain and / or the second Fc domain independently further comprises an amino acid substitution selected from the group consisting of L328R; S239K; S267K; S239K / A327G; and S267K / A327G according to EU numbering, and the Fc domain is derived from an Fc domain of IgG2. In some embodiments, the first Fc domain further comprises an amino acid substitution selected from the group consisting of L328R; S239K; S267K; S239K / A327G; and S267K / A327G according to EU numbering, and the Fc domain is derived from an Fc domain of IgG2. In some embodiments, the second Fc domain further comprises an amino acid substitution selected from the group consisting of: L328R; S239K; S267K; S239K / A327G; and S267K / A327G, according to EU numbering, and the Fc domain is derived from an IgG2 Fc domain. In some embodiments, the first Fc domain and the second Fc domain further comprise an amino acid substitution selected from the group consisting of: L328R; S239K; S267K; S239K / A327G; and S267K / A327G, according to EU numbering, and the Fc domain is derived from an IgG2 Fc domain.

[0125] Those skilled in the art will also understand that in Fc domains derived from IgG4, residue 234 is phenylalanine. Thus, those skilled in the art will understand that when the Fc domain is derived from an IgG4 Fc domain, references herein to L234 (e.g., L234V) are references to F234 (e.g., F234V). In some embodiments, the positions of the various Fc domain substitutions are relative to the corresponding positions in the wild-type IgG4 Fc domain (SEQ ID NO: 15). The amino acid sequence of the wild-type IgG4 Fc domain (SEQ ID NO: 15) is an exemplary sequence provided for comparison purposes, and the Fc domain of the heterodimeric protein may include additional amino acid changes (e.g., substitutions, insertions and deletions) compared to the wild-type IgG4 Fc domain (SEQ ID NO: 15). For example, the Fc domain of the heterodimeric protein may be derived from various wild-type human IgG4 alleles. In some embodiments, the Fc domain of the heterodimeric protein does not include any additional amino acid changes compared to the wild-type IgG4 Fc domain (SEQ ID NO: 15).

[0126] In some embodiments, each of the first Fc domain and / or the second Fc domain independently further comprises an amino acid substitution selected from the group consisting of: G236R / L328R; E233P / F234V / L235A / G236del / S239K; E233P / F234V / L235A / G236del / S267K; E233P / F234V / L235A / G236del / S239K / A327G; E233P / F234V / L235A / G236del / S267K / A327G; and E233P / F234V / L235A / G236del, according to EU numbering, and wherein the Fc domain is derived from an IgG4 Fc domain. In some embodiments, the first Fc domain further comprises an amino acid substitution selected from the group consisting of: G236R / L328R; E233P / F234V / L235A / G236del / S239K; E233P / F234V / L235A / G236del / S267K; E233P / F234V / L235A / G236del / S239K / A327G; E233P / F234V / L235A / G236del / S267K / A327G; and E233P / F234V / L235A / G236del, according to EU numbering, and wherein the Fc domain is derived from an IgG4 Fc domain. In some embodiments, the second Fc domain further comprises an amino acid substitution selected from the group consisting of: G236R / L328R; E233P / F234V / L235A / G236del / S239K; E233P / F234V / L235A / G236del / S267K; E233P / F234V / L235A / G236del / S239K / A327G; E233P / F234V / L235A / G236del / S267K / A327G; and E233P / F234V / L235A / G236del, according to EU numbering, and wherein the Fc domain is derived from an IgG4 Fc domain.In some embodiments, the first Fc domain and the second Fc domain further comprise amino acid substitutions selected from the group consisting of: G236R / L328R; E233P / F234V / L235A / G236del / S239K; E233P / F234V / L235A / G236del / S267K; E233P / F234V / L235A / G236del / S239K / A327G; E233P / F234V / L235A / G236del / S267K / A327G; and E233P / F234V / L235A / G236del, according to EU numbering, and wherein the Fc domain is derived from an IgG4 Fc domain.

[0127] In some embodiments, the first Fc domain further comprises the amino acid substitution M428L or N434S, according to EU numbering. In some embodiments, the first Fc domain further comprises the amino acid substitution M428L, according to EU numbering. In some embodiments, the first Fc domain further comprises the amino acid substitution N434S, according to EU numbering. In some embodiments, the second Fc domain further comprises the amino acid substitution M428L or N434S, according to EU numbering. In some embodiments, the second Fc domain further comprises the amino acid substitution M428L, according to EU numbering. In some embodiments, the second Fc domain further comprises the amino acid substitution N434S, according to EU numbering. In some embodiments, the first Fc domain further comprises the amino acid substitutions M428L and N434S, according to EU numbering. In some embodiments, the second Fc domain further comprises the amino acid substitutions M428L and N434S, according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each further comprise the amino acid substitutions M428L and N434S, according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each further comprise the amino acid substitution M428L, according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each further comprise the amino acid substitution N434S, according to EU numbering.

[0128] In some embodiments, the first Fc domain and / or the second Fc domain further comprises the amino acid substitution K246T, according to EU numbering. In some embodiments, the first Fc domain further comprises the amino acid substitution K246T, according to EU numbering. In some embodiments, the second Fc domain further comprises the amino acid substitution K246T, according to EU numbering. When the K246T substitution occurs in the second Fc domain, it is also referred to as a K100T mutation based on the amino acid numbering of the second monomer (see, e.g., SEQ ID NOs: 10 and 16). In some embodiments, the first Fc domain and the second Fc domain further comprise the amino acid substitution K246T, according to EU numbering.

[0129] In some embodiments, the first Fc domain comprises amino acid substitutions L368D and K370S; the second Fc domain comprises amino acid substitutions S364K and E357Q; and each of the first Fc domain and the second Fc domain further comprises amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, M428L, and N434S (all according to EU numbering). In some embodiments, the first Fc domain comprises amino acid substitutions S364K and E357Q; the second Fc domain comprises amino acid substitutions L368D and K370S; and each of the first Fc domain and the second Fc domain further comprises amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, M428L, and N434S (all according to EU numbering). In some embodiments, the first Fc domain comprises amino acid substitutions L368D and K370S; the second Fc domain further comprises amino acid substitutions S364K and E357Q; the first Fc domain and the second Fc domain each further comprise amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, M428L, and N434S (all according to EU numbering), and the IL-15 protein comprises amino acid substitutions D30N, E64Q, and N65D; and the IL-15Rα protein comprises SEQ ID NO:4. In some embodiments, the first Fc domain comprises amino acid substitutions S364K and E357Q; the second Fc domain comprises amino acid substitutions L368D and K370S; the first Fc domain and the second Fc domain each further comprise amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, M428L, and N434S (all according to EU numbering), and the IL-15 protein comprises amino acid substitutions D30N, E64Q, and N65D; and the IL-15Rα protein comprises SEQ ID NO:4.

[0130] In some embodiments, the first Fc domain comprises amino acid substitutions L368D and K370S; the second Fc domain comprises amino acid substitutions K246T, S364K, and E357Q; and each of the first Fc domain and the second Fc domain further comprises amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, M428L, and N434S (all according to EU numbering). In some embodiments, the first Fc domain comprises amino acid substitutions S364K and E357Q; the second Fc domain comprises amino acid substitutions K246T, L368D, and K370S; and each of the first Fc domain and the second Fc domain further comprises amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, M428L, and N434S (all according to EU numbering). In some embodiments, the first Fc domain comprises amino acid substitutions L368D and K370S; the second Fc domain comprises amino acid substitutions K246T, S364K, and E357Q; the first Fc domain and the second Fc domain each further comprise amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, M428L, and N434S (all according to EU numbering), and the IL-15 protein comprises amino acid substitutions D30N, E64Q, and N65D; and the IL-15Rα protein comprises SEQ ID NO:4. In some embodiments, the first Fc domain comprises amino acid substitutions S364K and E357Q; the second Fc domain comprises amino acid substitutions K246T, L368D, and K370S; the first Fc domain and the second Fc domain each further comprise amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, M428L, and N434S (all according to EU numbering), and the IL-15 protein comprises amino acid substitutions D30N, E64Q, and N65D; and the IL-15Rα protein comprises SEQ ID NO:4.

[0131] In some embodiments, the first Fc domain of the heterodimeric protein comprises the sequence set forth in SEQ ID NO: 6. In some embodiments, the second Fc domain of the heterodimeric protein comprises the sequence set forth in SEQ ID NO: 7. In some embodiments, the second Fc domain of the heterodimeric protein comprises the sequence set forth in SEQ ID NO: 8.

[0132] In some embodiments, any one of the amino acid substitutions of the Fc variant domains described herein is on one or both of the monomers (e.g., on the first Fc domain; on the second Fc domain or on both Fc domains).

[0133] In some embodiments, the Fc domain of the first monomer is derived from IgG1, IgG2, IgG3, or IgG4. In some embodiments, the Fc domain of the first monomer is derived from IgG1. In some embodiments, the Fc domain of the first monomer is derived from IgG2. In some embodiments, the Fc domain of the first monomer is derived from IgG3. In some embodiments, the Fc domain of the first monomer is derived from IgG4. In some embodiments, the Fc domain of the second monomer is derived from IgG1, IgG2, IgG3, or IgG4. In some embodiments, the Fc domain of the second monomer is derived from IgG1. In some embodiments, the Fc domain of the second monomer is derived from IgG2. In some embodiments, the Fc domain of the second monomer is derived from IgG3. In some embodiments, the Fc domain of the second monomer is derived from IgG4.

[0134] As used herein, "IL-15", "IL15" or "Interleukin 15" may be used interchangeably and refer to a four-α-helical protein that belongs to a family of cytokines. IL-15 signals through a receptor complex composed of the IL-2 / IL-15 receptor β (IL-15Rβ) (CD122) subunit. In some embodiments, the IL-15 protein comprises a polypeptide sequence set forth in SEQ ID NO:2 (full-length human IL-15). In some embodiments, the IL-15 protein comprises a polypeptide sequence set forth in SEQ ID NO:1 (truncated or mature human IL-15). In some embodiments, the IL-15 protein comprises a polypeptide sequence selected from the group consisting of SEQ ID NO:1 and SEQ ID NO:2.

[0135] In some embodiments, the first monomeric IL-15 protein is an IL-15 protein variant having an amino acid sequence different from the wild-type IL-15 protein (SEQ ID NO: 1). In some embodiments, the IL-15 variant has a reduced binding affinity (compared to wild-type IL-15) to the IL-2 / IL-15βγ receptor complex and a CD8 +The IL-15 protein variants are engineered to ultimately promote anti-tumor immunity through IL-15-mediated signaling on T cells and NK cells. In certain embodiments, the sequence of the first monomeric IL-15 protein variant has at least one (i.e., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions compared to the wild-type IL-15 sequence protein (SEQ ID NO: 1). In some embodiments, the amino acid substitutions may include one or more amino acid substitutions or deletions in the domains of IL-15 that interact with IL-15R and / or the IL-2 / IL-15βγ receptor complex. In some embodiments, the amino acid substitutions may include one or more amino acid substitutions or deletions in the domains of IL-15 protein that cause a decrease in binding affinity to the IL-2 / IL-15βγ receptor complex compared to the affinity of wild-type IL-15. In some embodiments, the IL-15 protein comprises one or more amino acid substitutions selected from the group consisting of N1D, N4D, D8N, D30N, D61N, E64Q, N65D and Q108E. In some embodiments, the IL15 protein comprises one or more amino acid substitutions selected from the group consisting of E87C, V49C, L52C, E89C, Q48C, E53C, C42S and L45C. The amino acid substitutions of the IL-15 protein described herein are relative to wild-type IL-15 (mature form; SEQ ID NO: 1). The amino acid sequence of wild-type IL-15 (mature form; SEQ ID NO: 1) is an exemplary sequence provided for comparison purposes, and the IL-15 protein of the heterodimeric protein may comprise additional amino acid changes (e.g., substitutions, insertions and deletions) relative to the wild-type IL-15. For example, the IL-15 protein of the heterodimeric protein may be derived from various wild-type human IL-15 alleles. In some embodiments, the IL-15 protein of the heterodimeric protein does not contain any additional amino acid changes compared to wild-type IL-15. In some embodiments, the IL-15 protein variant present in the first monomer comprises the amino acid sequence set forth in SEQ ID NO:5 (XENP24306 / XENP32803). In some embodiments, the IL-15 protein comprises the amino acid sequence set forth in SEQ ID NO:5.

[0136] In some embodiments, the IL-15 protein comprises the amino acid substitutions D30N, E64Q and N65D. In some embodiments, the IL-15 protein comprises the following amino acid substitutions: N4D and N65D. In some embodiments, the IL-15 protein comprises the following amino acid substitutions: D30N and N65D. In some embodiments, the IL-15 protein present in the first monomer comprises the N65D amino acid substitution and one or more amino acid substitutions selected from the group consisting of N4D, D30N, E64Q. In some embodiments, the IL-15 protein present in the first monomer comprises the N65D amino acid substitution and one or more amino acid substitutions selected from the group consisting of N4D, D30N, E64Q. In some embodiments, the IL-15 protein present in the first monomer comprises the N65D amino acid substitution and consists of the amino acid substitutions N4D, D30N, E64Q. The amino acid substitutions of the IL-15 protein described herein are relative to wild-type IL-15 (SEQ ID NO: 1). The amino acid sequence of wild-type IL-15 (SEQ ID NO: 1) is an exemplary sequence provided for comparison purposes, and the IL-15 protein of the heterodimeric protein may include additional amino acid changes (e.g., substitutions, insertions, and deletions) relative to wild-type IL-15. For example, the IL-15 protein of the heterodimeric protein may be derived from various wild-type human IL-15 alleles. In some embodiments, the IL-15 protein of the heterodimeric protein does not include any additional amino acid changes compared to wild-type IL-15.

[0137] The IL-15Rα protein is a transmembrane protein with extremely high affinity for IL-15, which promotes the transport of IL-15 from the endoplasmic reticulum (ER) through the cytoplasm and the presentation of the IL-15 / IL-15Rα complex on the cell surface. As used herein, the term "IL-15Rα sushi domain" refers to the truncated extracellular region of IL-15Rα or recombinant human IL-15 receptor α. In some embodiments, the IL-15Rα protein comprises the polypeptide sequence of SEQ ID NO:3 (full-length human IL-15Rα). In some embodiments, the IL-15Rα protein comprises the polypeptide sequence of SEQ ID NO:4 (human IL-15Rα sushi domain).

[0138] In some embodiments, the IL15Rα protein comprises one or more amino acid changes selected from the group consisting of a DPC or DCA insertion after residue 65 (65DPC or D96 / P97 / C98, 65DCA or D96 / C97 / A98), S40C, K34C, G38C, L42C, and A37C. The numbering of these amino acid substitutions in the IL-15Rα protein is relative to the sushi domain of human IL-15Rα (SEQ ID NO: 4). The amino acid sequence of the sushi domain of human IL-15Rα (SEQ ID NO: 4) is an exemplary sequence provided for comparison purposes, and the IL-15Rα protein of the heterodimeric protein may comprise additional amino acid changes (e.g., substitutions, insertions, and deletions) relative to the sushi domain of human IL-15Rα (SEQ ID NO: 4). For example, the IL-15Rα protein of the heterodimeric protein may be derived from various wild-type human IL-15Rα alleles. In some embodiments, the IL-15Rα protein of the heterodimeric protein does not contain any additional amino acid changes to the sushi domain of human IL-15Rα (SEQ ID NO:4).

[0139] In some embodiments, the IL15 protein and the IL15Rα protein each contain a set of amino acid substitutions or additions selected from the group consisting of: E87C:65DPC (DPC insertion after residue 65 or D96 / P97 / C98); E87C:65DCA (DCA insertion after residue 65 or D96 / C97 / A98); V49C:S40C; L52C:S40C; E89C:K34C; Q48C:G38C; E53C:L42C; C42S:A37C; and L45C:A37C. The numbering of these amino acid substitutions in the IL-15Rα protein is relative to the sushi domain of human IL-15Rα (SEQ ID NO: 4). The amino acid sequence of the sushi domain of human IL-15Rα (SEQ ID NO: 4) is an exemplary sequence provided for comparison purposes, and the IL-15Rα protein of the heterodimeric protein may include additional amino acid changes (e.g., substitutions, insertions, and deletions) relative to the sushi domain of human IL-15Rα (SEQ ID NO: 4). For example, the IL-15Rα of the heterodimeric protein may be derived from various wild-type human IL-15α alleles. In some embodiments, the IL-15Rα protein of the heterodimeric protein does not include any additional amino acid changes relative to the sushi domain of human IL-15Rα (SEQ ID NO: 4).

[0140] In some embodiments, the IL-15Rα protein comprises a polypeptide sequence selected from the group consisting of SEQ ID NO:3 and SEQ ID NO:4. In some embodiments, the IL-15Rα protein comprises the amino acid sequence of SEQ ID NO:3 (full-length human IL-15Rα). In some embodiments, the IL-15Rα protein comprises the amino acid sequence of SEQ ID NO:4 (sushi domain of human IL-15Rα). In some embodiments, the IL-15 protein comprises the amino acid substitutions D30N, E64Q, and N65D; the IL-15Rα protein comprises SEQ ID NO:4 (sushi domain of human IL-15Rα).

[0141] The heterodimeric protein of the present disclosure is an IL-15 / IL-15Rα-Fc heterodimeric fusion protein. One N-terminus of the heterodimeric Fc domain is covalently linked to the C-terminus of the IL-15 protein, and the other is covalently linked to the sushi domain (truncated extracellular region) of IL-15Rα. In some embodiments, the IL-15 protein and IL-15Rα (sushi domain) can have a variable length linker between the C-terminus of IL-15 and IL-15Rα and the N-terminus of each of the Fc domains. In some embodiments, the IL-15 protein is covalently linked to the N-terminus of the first Fc domain via a first linker. In some embodiments, the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain using a second linker. In some embodiments, the IL-15 protein is covalently linked to the N-terminus of the first Fc domain via a first linker, and the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain via a second linker. The term "linker" as used herein refers to a polypeptide sequence that connects two or more domains. The properties of linkers and their stability for a particular purpose are known in the art. See, for example, Chen et al. Adv Drug Deliv Rev. October 15; 65(10): 1357-1369 (2013) (disclosing various types of linkers, their properties, and related linker design tools and databases), which is incorporated herein by reference. In some embodiments, the linker is flexible, rigid, or in vivo cleavable. In some embodiments, the linker is flexible. In some embodiments, the first linker and / or the second linker are independently variable-length Gly-Ser linkers. Flexible linkers typically contain small non-polar amino acids (e.g., Gly) or polar amino acids (e.g., Ser or Thr). An example of a flexible linker that can be used in the present disclosure is a sequence that consists primarily of a stretch of Gly and Ser residues (a "GS" linker). In some embodiments, the flexible linker contains four repeats of Gly and Ser residues.In some embodiments, the flexible linker comprises 1-5 repeats of five Gly and Ser residues. Non-limiting examples of flexible linkers include (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO:39), (Ser-Ser-Ser-Ser-Gly)n (SEQ ID NO:40), (Gly-Ser-Ser-Gly-Gly)n (SEQ ID NO:41) and (Gly-Gly-Ser-Gly-Gly)n (SEQ ID NO:42), where n can be any integer from 1 to 5. In some embodiments, the linker is 5 to 25 amino acid residues long. In some embodiments, the flexible linker comprises 5, 10, 15, 20, or 25 residues. Other suitable linkers may be selected from the group consisting of AS (SEQ ID NO: 43), AST (SEQ ID NO: 44), TVAAPS (SEQ ID NO: 45), TVA (SEQ ID NO: 46), ASTSGPS (SEQ ID NO: 47), KESGSVSSEQLAQFRSLD (SEQ ID NO: 48), EGKSSGSGSESKST (SEQ ID NO: 49), (Gly)6 (SEQ ID NO: 50), (Gly)8 (SEQ ID NO: 51), and GSAGSAAGSGEF (SEQ ID NO: 52). In general, flexible linkers provide good flexibility and solubility and may function as passive linkers to maintain distance between functional domains. The length of the flexible linker may be adjusted to allow proper folding or to achieve optimal biological activity of the fusion protein. In some embodiments, the linker comprises the sequence (Gly-Gly-Gly-Gly-Ser; SEQ ID NO: 53). In some embodiments, the first linker and the second linker comprise different sequences. In some embodiments, the first linker and the second linker comprise the same sequence. In some embodiments, the first linker and the second linker comprise the sequence set forth in SEQ ID NO: 53. In some embodiments, the first linker and the second linker consist of the sequence set forth in SEQ ID NO: 53.

[0142] In some embodiments, a heterodimeric protein useful in the methods described herein comprises: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain; and (ii) a second monomer comprising a sushi domain of an IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain; each of the first Fc domain and the second Fc domain independently comprise the amino acid substitutions E233P, L234V, L235A, G236del, and S267K, according to EU numbering; and the IL-15 protein comprises an N65D amino acid substitution and one or more amino acid substitutions selected from the group consisting of N4D, D30N, E64Q. The positions of the various Fc domain substitutions are relative to the corresponding positions in the wild-type IgG1 Fc domain (SEQ ID NO: 12). The amino acid sequence of the wild-type IgG1 Fc domain (SEQ ID NO: 12) is an exemplary sequence provided for comparison purposes, and the IL-15Rα protein of the heterodimeric protein may contain additional amino acid changes (e.g., substitutions, insertions, and deletions) relative to the wild-type IgG1 Fc domain (SEQ ID NO: 12). For example, the Fc domain of the heterodimeric protein may be derived from different wild-type human IgG1 alleles. In some embodiments, the Fc domain of the heterodimeric protein does not contain any additional amino acid changes relative to the wild-type IgG1 Fc domain (SEQ ID NO: 12). The amino acid substitutions of the IL-15 protein described herein are relative to wild-type IL-15 (mature form; SEQ ID NO: 1). The amino acid sequence of wild-type IL-15 (mature form; SEQ ID NO:1) is an exemplary sequence provided for comparison purposes, and the IL-15 proteins of the heterodimeric protein may include additional amino acid alterations (e.g., substitutions, insertions, and deletions) relative to the wild-type IL-15. For example, the IL-15 proteins of the heterodimeric protein may be derived from various wild-type human IL-15 alleles.In some embodiments, the IL-15 protein of the heterodimeric protein does not comprise any additional amino acid alterations compared to wild-type IL-15.

[0143] A person skilled in the art would be able to determine the corresponding substitutions in the Fc domain derived from the Fc domain of IgG2, IgG3 or IgG4. For example, a person skilled in the art would know that residues E233, L234, L235, G236 and A327 are present in the Fc domain derived from the Fc domain of IgG1 or IgG3. In some embodiments, the positions of the various Fc domain substitutions are based on the corresponding positions in the Fc domain of wild-type IgG3 (SEQ ID NO: 14). The amino acid sequence of the wild-type IgG3 Fc domain (SEQ ID NO: 14) is an exemplary sequence provided for comparison purposes, and the IL-15Rα protein of the heterodimeric protein may include additional amino acid changes (e.g., substitutions, insertions and deletions) compared to the wild-type IgG3 Fc domain (SEQ ID NO: 14). For example, the Fc domain of the heterodimeric protein may be derived from a different wild-type human IgG3 allele. In some embodiments, the Fc domain of the heterodimeric protein does not include any additional amino acid changes compared to the wild-type IgG3 Fc domain (SEQ ID NO: 14). Thus, one of skill in the art will appreciate that each of the first Fc domain and the second Fc domain independently comprises the amino acid substitutions E233P, L234V, L235A, G236del, and S267K (according to EU numbering) when the Fc domain is derived from an IgG1 or IgG3 Fc domain.

[0144] The skilled artisan will also understand that the corresponding residues in an Fc domain derived from an IgG2 Fc domain are P233, V234, A235 and G327, and that an Fc domain derived from an IgG2 lacks a residue corresponding to residue G236. Thus, the skilled artisan will understand that when the Fc domain is an IgG2 Fc domain (i.e. the PVA-sequence present in wild type IgG2), references herein to E233P, L234V, L235A G236del and A327G are references to P233, V234, A235, -236, and not the substitution at residue 327. In some embodiments, the positions of the various Fc domain substitutions are relative to the corresponding positions in the wild type IgG2 Fc domain (SEQ ID NO: 13). The amino acid sequence of the wild-type IgG2 Fc domain (SEQ ID NO: 13) is an exemplary sequence provided for comparison purposes, and the IL-15Rα protein of the heterodimeric protein may contain additional amino acid changes (e.g., substitutions, insertions and deletions) compared to the wild-type IgG2 Fc domain (SEQ ID NO: 13). For example, the Fc domain of the heterodimeric protein may be derived from various wild-type human IgG2 alleles. In some embodiments, the Fc domain of the heterodimeric protein does not contain any additional amino acid changes compared to the wild-type IgG2 Fc domain (SEQ ID NO: 13). Thus, one skilled in the art will understand that each of the first Fc domain and the second Fc domain independently contains the amino acid substitution S267K, according to EU numbering, when the Fc domain is derived from the Fc domain of IgG2.

[0145] Those skilled in the art will also understand that in an Fc domain derived from IgG4, residue 234 is a phenylalanine and residue 327 is a glycine. Thus, those skilled in the art will understand that when the Fc domain is derived from an IgG4 Fc domain, references herein to L234 (e.g., L234V) and A327 (e.g., A327G) are references to F234 (e.g., F234V), respectively, and not substitutions at residue 327. In some embodiments, the positions of the various Fc domain substitutions are relative to the corresponding positions in the wild-type IgG4 Fc domain (SEQ ID NO: 15). The amino acid sequence of the wild-type IgG4 Fc domain (SEQ ID NO: 15) is an exemplary sequence provided for comparison purposes, and the IL-15Rα protein of the heterodimeric protein may include additional amino acid changes (e.g., substitutions, insertions and deletions) compared to the wild-type IgG4 Fc domain (SEQ ID NO: 15). For example, the Fc domain of the heterodimeric protein may be derived from various wild-type human IgG4 alleles. In some embodiments, the Fc domain of the heterodimeric protein does not comprise any additional amino acid changes compared to the wild-type IgG4 Fc domain (SEQ ID NO: 15). Thus, one of skill in the art will understand that when the Fc domain is derived from an IgG4 Fc domain, the first Fc domain and the second Fc domain each independently comprise the amino acid substitutions E233P, F234V, L235A, G236del, and S267K (according to EU numbering).

[0146] In some embodiments, the first Fc domain and / or the second Fc domain are independently engineered to further extend systemic exposure at lower pH (6.0) and extend half-life through enhanced FcRn binding. In some embodiments, additional engineering to the Fc region renders the heterodimeric proteins of the present disclosure effector-free (i.e., abolishes binding to Fcγ receptors) and eliminates antibody-mediated CL in T cells and NK cells. In some embodiments, the first Fc domain and / or the second Fc domain are independently engineered to favor heterodimerization over homodimerization. In some embodiments, the first Fc domain and / or the second Fc domain are independently engineered to have improved PK. In some embodiments, the first Fc domain and / or the second Fc domain are independently engineered to increase the pI difference between the two monomers, thereby allowing purification of homodimers from heterodimers. In some embodiments, the Fc variant domain may further comprise a molecule or sequence lacking one or more native Fc amino acid residues that affect or are involved in (1) disulfide bond formation, (2) incompatibility with a selected host cell, (3) terminal heterogeneity upon expression in a selected host cell, (4) glycosylation, (5) interaction with complement, (6) binding to an Fc receptor other than the neonatal receptor, (7) antibody-dependent cell-mediated cytotoxicity (ADCC), or (8) antibody-dependent cellular phagocytosis (ADCP). Fc variants are described in more detail below.

[0147] In some embodiments, the first or second Fc domain of the present disclosure may comprise a "skew" variant (e.g., a set of amino acid substitutions shown in Figures 1A-1C of U.S. Patent No. 10,259,887; all of which are incorporated herein by reference in their entireties). Skew variants favor the formation of heterodimers over the formation of homodimers. In some embodiments, the scubariant is selected from the group consisting of: S364K / E357Q (on the first Fc domain):L368D / K370S (on the second Fc domain); L368D / K370S:S364K; L368E / K370S:S364K; T411E / K360E / Q362E:D401K; L368D / K370S:S364K / E357L, K370S:S364K / E357Q, T366S / L368A / Y407V:T366W and T366S / L368A / Y407V / Y349C:T366W / S354C, according to EU numbering. In some embodiments, the first Fc domain further comprises amino acid substitutions L368D and K370S according to EU numbering, and the second Fc domain further comprises amino acid substitutions S364K and E357Q according to EU numbering. In some aspects, the first Fc domain further comprises amino acid substitutions S364K and E357Q according to EU numbering, and the second Fc domain further comprises amino acid substitutions L368D and K370S according to EU numbering.

[0148] Other methods for generating heterodimeric proteins (e.g., bispecific antibodies or heterodimeric Fc fusion proteins) are known in the art and include, but are not limited to, "nobs-into-holes" technology and DuoBody® technology. See, e.g., Liu et al., "Fc Engineering for Developing Therapeutic Bispecific Antibodies and Novel Scaffolds," Front. Immunol. 2017 vol. 8, article 38; Ridgway et al., "Knobs-into-holes' engineering of antibody CH3 domains for heavy chain heterodimerization," Protein Eng. 1996, vol. 9(7):617-21; Atwell et al., "Stable heterodimers from remodeling the domain interface of a homodimer using a phage display library," J Mol Biol. 1997 vol. 270:26-35; Merchant et al., "An efficient route to human bispecific IgG," Nat Biotechnol. 1998 vol 16:677-81; U.S. Patent No. 8,216,805, et al.; Gramer et al., "Production of stable bispecific IgG1 by controlled "Fab-arm exchange", mAbs5(6):962-973(2013);Labrijn et al. "Efficient generation of stable bispecific IgG1 by controlled Fab-arm exchange" PNAS110(13):5145-5150(2013);Labrijn et al. "Controlled Fab-arm exchange for the generation of stable bispecific IgG1"Nature Protocols9(10):2450-63(2014);Labrijn et al.See, "Efficient Generation of Bispecific Murine Antibodies for Pre-Clinical Investigations in Syngeneic Rodent Models," Scientific Reports 7(1):1-14 (2017); and van den Bremer et al., "Cysteine-SILAC Mass Spectrometry Enabling the Identification and Quantitation of Scrambled Interchain Disulfide Bonds: Preservation of Native Heavy-Light Chain Pairing in Bispecific IgGs Generated by Controlled Fab-arm Exchange," Analytical Chemistry 89(20), 10873-10882 (2017). Any such techniques may be used to generate the heterodimeric proteins of the present disclosure.

[0149] In some embodiments, the first Fc domain further comprises an amino acid substitution selected from the group consisting of Q295E, N384D, Q418E and N421D, or a combination thereof, according to EU numbering. In some embodiments, the second Fc domain further comprises any one of the amino acid substitutions selected from the group consisting of Q295E, N384D, Q418E and N421D, or a combination thereof, according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain each further comprise any one of the amino acid substitutions selected from the group consisting of Q295E, N384D, Q418E and N421D, or a combination thereof, according to EU numbering. In some embodiments, the first Fc domain further comprises the amino acid substitutions Q295E, N384D, Q418E and N421D, according to EU numbering. In some embodiments, the second Fc domain further comprises the amino acid substitutions Q295E, N384D, Q418E and N421D, according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain further comprise the amino acid substitutions Q295E, N384D, Q418E and N421D, according to EU numbering.

[0150] In some embodiments, the first Fc domain does not comprise a free cysteine ​​at position 220 according to EU numbering. In some embodiments, the first Fc domain comprises the amino acid substitution C220S according to EU numbering. In some embodiments, the second Fc domain does not comprise a free cysteine ​​at position 220 according to EU numbering. In some embodiments, the second Fc domain comprises the amino acid substitution C220S according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain do not comprise a free cysteine ​​at position 220 according to EU numbering. In some embodiments, the first Fc domain and the second Fc domain comprise the amino acid substitution C220S according to EU numbering.

[0151] In some embodiments, the first Fc domain or the second Fc domain of the disclosure may comprise an amino acid substitution (Xtend substitution) for improved PK. In some embodiments, the first Fc domain and / or the second Fc domain of the disclosure independently comprise the amino acid substitution M428L and / or N434S, according to EU numbering. In some embodiments, the first Fc domain comprises the amino acid substitution M428L or N434S. In some embodiments, the first Fc domain comprises the amino acid substitution M428L and N434S. In some embodiments, the first Fc domain comprises the amino acid substitution M428L. In some embodiments, the first Fc domain comprises the amino acid substitution N434S. In some embodiments, the second Fc domain comprises the amino acid substitution M428L or N434S. In some embodiments, the second Fc domain comprises the amino acid substitution M428L and N434S. In some embodiments, the second Fc domain comprises the amino acid substitution M428L. In some embodiments, the second Fc domain comprises the amino acid substitution N434S. In some embodiments, the first Fc domain and the second Fc domain comprise the amino acid substitution M428L. In some embodiments, the first Fc domain and the second Fc domain each comprise the amino acid substitution N434S. In some embodiments, the first Fc domain and the second Fc domain each comprise the amino acid substitutions M428L and N434S.

[0152] In some embodiments, the first Fc domain and / or the second Fc domain further comprises the amino acid substitution K246T, according to EU numbering. In some embodiments, the first Fc domain further comprises the amino acid substitution K246T, according to EU numbering. In some embodiments, the second Fc domain further comprises the amino acid substitution K246T, according to EU numbering. When the K246T substitution occurs in the second Fc domain, it is also referred to as a K100T mutation based on the amino acid numbering of the second monomer (see, e.g., SEQ ID NOs: 10 and 16). In some embodiments, the first Fc domain and the second Fc domain further comprise the amino acid substitution K246T, according to EU numbering.

[0153] In some embodiments, the first Fc domain of the heterodimeric protein comprises the sequence set forth in SEQ ID NO: 6. In some embodiments, the second Fc domain of the heterodimeric protein comprises the sequence set forth in SEQ ID NO: 7. In some embodiments, the second Fc domain of the heterodimeric protein comprises the sequence set forth in SEQ ID NO: 8.

[0154] In some embodiments, any one of the amino acid substitutions of the Fc variant domains described herein is present on one or both of the monomers (e.g., on the first Fc domain; on the second Fc domain or on both Fc domains).

[0155] In some embodiments, the Fc domain of the first monomer is derived from IgG1, IgG2, IgG3, or IgG4. In some embodiments, the Fc domain of the first monomer is derived from IgG1. In some embodiments, the Fc domain of the first monomer is derived from IgG2. In some embodiments, the Fc domain of the first monomer is derived from IgG3. In some embodiments, the Fc domain of the first monomer is derived from IgG4. In some embodiments, the Fc domain of the second monomer is derived from IgG1, IgG2, IgG3, or IgG4. In some embodiments, the Fc domain of the second monomer is derived from IgG1. In some embodiments, the Fc domain of the second monomer is derived from IgG2. In some embodiments, the Fc domain of the second monomer is derived from IgG3. In some embodiments, the Fc domain of the second monomer is derived from IgG4.

[0156] In some embodiments, the first Fc domain comprises the following amino acid substitutions according to EU numbering: C220S, E233P, L234V, L235A, G236del, S267K, L368D, K370S, M428L, and N434S. In some embodiments, the second Fc domain comprises the following amino acid substitutions according to EU numbering: C220S, E233P, L234V, L235A, G236del, S267K, S364K, E357Q, M428L, and N434S. In some embodiments, the second Fc domain comprises the following amino acid substitutions according to EU numbering: C220S, E233P, L234V, L235A, G236del, S267K, L368D, K370S, M428L, and N434S. In some embodiments, the first Fc domain comprises the following amino acid substitutions: C220S, E233P, L234V, L235A, G236del, S267K, S364K, E357Q, M428L and N434S according to EU numbering. In some embodiments, the first Fc domain does not comprise any additional amino acid changes compared to the Fc domain of a wild-type IgG. In some embodiments, the first Fc domain does not comprise any additional amino acid changes compared to the Fc domain of a wild-type IgG1. In some embodiments, the first Fc domain does not comprise any additional amino acid changes compared to SEQ ID NO: 12. In some embodiments, the second Fc domain does not comprise any additional amino acid changes compared to the Fc domain of a wild-type IgG. In some embodiments, the second Fc domain does not comprise any additional amino acid changes compared to the Fc domain of a wild-type IgG1. In some embodiments, the second Fc domain does not comprise any additional amino acid changes compared to SEQ ID NO: 12.

[0157] In some embodiments, each of the first Fc domain and the second Fc domain independently comprises a set of additional amino acid substitutions selected from the group consisting of G236R, S239K, L328R and A327G according to EU numbering.

[0158] In some embodiments, the heterodimeric protein comprises (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain, and (ii) a second monomer comprising a wild-type sushi domain of an IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain; the first Fc domain is comprised of amino acid sequence 1444-1444 according to EU numbering. the second Fc domain comprises amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, Q295E, L368D, K370S, N384D, Q418E, N421D, M428L, and N434S; the IL-15 protein comprises amino acid substitutions D30N, E64Q, and N65D compared to the wild-type IL-15 protein (SEQ ID NO: 1).

[0159] In some embodiments, the heterodimeric protein comprises (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain, and (ii) a second monomer comprising a sushi domain of a wild type IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain; the first Fc domain comprises amino acid substitutions C220S, E23 the second Fc domain comprises the amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, Q295E, E357Q, S364K, N384D, Q418E, N421D, M428L, and N434S, according to EU numbering; and the IL-15 protein comprises the amino acid substitutions D30N, E64Q, and N65D compared to the wild-type IL-15 protein (SEQ ID NO: 1).

[0160] In some embodiments, the heterodimeric protein comprises (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain, and (ii) a second monomer comprising a sushi domain of a wild type IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain; the first Fc domain comprises the amino acid substitutions C220S, E233P, L220S, L233R, L23 ... the second Fc domain comprises the amino acid substitutions C220S, E233P, L234V, L235A, G236del, K246T, S267K, E357Q, S364K, M428L, and N434S, according to EU numbering; and the IL-15 protein comprises the amino acid substitutions D30N, E64Q, and N65D compared to the wild-type IL-15 protein (SEQ ID NO: 1).

[0161] In some embodiments, the heterodimeric protein comprises (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain, and (ii) a second monomer comprising a sushi domain of a wild type IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain; the first Fc domain comprises the amino acid substitutions C220S, E233P, L220S, L233R, L23 ... the second Fc domain comprises the amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, Q295E, E357Q, S364K, N384D, Q418E, N421D, M428L, and N434S, according to EU numbering; and the IL-15 protein comprises the amino acid substitutions D30N, E64Q, and N65D compared to the wild-type IL-15 protein (SEQ ID NO: 1).

[0162] In some embodiments, the first monomer comprises the amino acid sequence set forth in SEQ ID NO:9 and the second monomer comprises the amino acid sequence set forth in SEQ ID NO:10. In some embodiments, the first monomer comprises the amino acid sequence set forth in SEQ ID NO:9 and the second monomer comprises the amino acid sequence set forth in SEQ ID NO:16.

[0163] In some embodiments, the first monomer comprises (1) IL-15 and (2) a first Fc domain comprising the sequence set forth in SEQ ID NO: 6. In some embodiments, the second monomer comprises (1) IL-15Rα and (2) a second Fc domain comprising the sequence set forth in SEQ ID NO: 7.

[0164] In some embodiments, the amino acid substitutions present in the heterodimeric protein are as disclosed in U.S. Patent Application Publication No. 2018 / 0118805, which is incorporated by reference in its entirety.

[0165] The sequences referred to herein are shown in Table 1 below. It is known in the art that during processing and expression of Fc-containing proteins, C-terminal lysine can be cleaved (also known in the art as C-terminal lysine clipping). Thus, for each sequence described herein that includes a C-terminal lysine, the corresponding sequence that does not include the C-terminal lysine (i.e., the C-terminal lysine cleavage product) is also contemplated. In some embodiments, the first monomer includes a C-terminal lysine. In some embodiments, the first monomer lacks a C-terminal lysine. In some embodiments, the second monomer includes a C-terminal lysine. In some embodiments, the second monomer lacks a C-terminal lysine.

[0166] It is also known in the art that the C-terminal cleavage process is imprecise and additional C-terminal residues are truncated. Thus, for each sequence described herein that includes a C-terminal lysine, a corresponding sequence that does not include the two C-terminal residues is also contemplated. In some embodiments, for each sequence described herein that includes a C-terminal lysine, a corresponding sequence that does not include the three C-terminal residues is also contemplated. In some embodiments, for each sequence described herein that includes a C-terminal lysine, a corresponding sequence that does not include the four C-terminal residues is also contemplated. In some embodiments, for each sequence described herein that includes a C-terminal lysine, a corresponding sequence that does not include the five C-terminal residues is also contemplated. In some embodiments, for each sequence described herein that includes a C-terminal lysine, a corresponding sequence that does not include the six C-terminal residues is also contemplated. In some embodiments, for each sequence described herein that includes a C-terminal lysine, a corresponding sequence that does not include the seven C-terminal residues is also contemplated. In some embodiments, for each sequence described herein that includes a C-terminal lysine, a corresponding sequence that does not include the eight C-terminal residues is also contemplated. In some embodiments, for each sequence described herein that includes a C-terminal lysine, a corresponding sequence that does not include the nine C-terminal residues is also contemplated. In some embodiments, for each sequence described herein that includes a C-terminal lysine, a corresponding sequence that does not include the 10 C-terminal residues is also contemplated. In some embodiments, for each sequence described herein that includes a C-terminal lysine, a corresponding sequence that does not include the 11 C-terminal residues is also contemplated. In some embodiments, for each sequence described herein that includes a C-terminal lysine, a corresponding sequence that does not include the 12 C-terminal residues is also contemplated. In some embodiments, for each sequence described herein that includes a C-terminal lysine, a corresponding sequence that does not include the 13 C-terminal residues is also contemplated. In some embodiments, for each sequence described herein that includes a C-terminal lysine, a corresponding sequence that does not include the 14 C-terminal residues is also contemplated. In some embodiments, for each sequence described herein that includes a C-terminal lysine, a corresponding sequence that does not include the 15 C-terminal residues is also contemplated.In some embodiments, the missing C-terminal residues are the result of manipulation (eg, expressing a polynucleotide that lacks a nucleotide sequence encoding one or more of the C-terminal residues). [Table 1] TIFF2024527047000003.tif237170TIFF2024527047000004.tif233170

[0167] In some embodiments, the heterodimeric protein of the disclosure is selected from the group consisting of XENP20818, XENP20819, XENP21471, XENP21472, XENP21473, XENP21474, XENP21475, XENP21476, XENP21477, XENP21988, XENP21989, XENP21990, XENP21991, XENP21992, XENP22013, XENP22014, XENP22015, XENP22016, XENP22017, XENP22018, XENP22019, XENP22018, XENP22019, XENP22018, XENP22019, XENP22019, XENP22020, XENP22021, XENP22022, XENP22023, XENP22024, XENP22025, XENP22026, XENP22027, XENP22028, XENP22029, XENP22030, XENP22031, XENP22032, XENP22033, XENP22034, XENP22035, XENP22036, XENP22037, XENP22038, XENP22039, XENP22040, XENP22041, XENP22042, XENP22043, XENP22044, XENP22045, XENP22046, XENP22047, XENP220 NP22014, XENP22015, XENP22017, XENP22815, XENP22816, XENP22817, XENP22818, XENP22819, XENP22820, XE NP22821, XENP22822, XENP22823, XENP22824, XENP22825, XENP22826, XENP22827, XENP22828, XENP22829, XEN P22830, XENP22831, XENP22832, XENP22833, XENP22834, XENP23343, XENP23472, XENP23504, XENP23554, XEN P23555, XENP23557, XENP23559, XENP23560, XENP23561, XENP24017, XENP24018, XENP24019, XENP24020, XENP No. 10,501,543, and are incorporated herein by reference.

[0168] In some embodiments, the heterodimeric protein of the present disclosure is selected from the group consisting of XENP22822, XENP23504, XENP24045, XENP24306, XENP22821, XENP23343, XENP23557, XENP24113, XENP24051, XENP24341, XENP24052, XENP24301, and XENP32803 heterodimeric proteins, which are described in Table 2 below. The sequences of XENP22822, XENP23504, XENP24045, XENP24306, XENP22821, XENP23343, XENP23557, XENP24113, XENP24051, XENP24341, XENP24052, and XENP24301 are also shown in US Patent Application Publication No. 2018 / 0118805, which is incorporated herein by reference. In some embodiments, the heterodimeric protein of the present disclosure is XENP24306. In some embodiments, the heterodimeric protein of the present disclosure is XENP32803. In some embodiments, the heterodimeric protein is XENP24306, XENP32803, or a combination thereof. In some embodiments, a combination of two or more (e.g., two, three, four, five, etc.) heterodimeric proteins of the present disclosure are used in the methods described herein. In some embodiments, a combination of two heterodimeric proteins of the present disclosure (i.e., a first heterodimeric protein and a second heterodimeric protein of the present disclosure) are used in the methods described herein. In some embodiments, the first heterodimeric protein comprises a first monomer comprising the amino acid sequence shown in SEQ ID NO:9 and a second monomer comprising the amino acid sequence shown in SEQ ID NO:10, and the second heterodimeric protein comprises a first monomer comprising the amino acid sequence shown in SEQ ID NO:9 and a second monomer comprising the amino acid sequence shown in SEQ ID NO:16. In some embodiments, a combination of XENP24306 and XENP32803 is used in the methods described herein.

[0169] In some embodiments, the XENP24306 protein comprises about 99%, about 98%, about 97%, about 96%, about 95%, about 94%, about 93%, about 92%, about 91%, about 90%, about 89%, about 88%, about 87%, about 86%, about 85%, about 84%, about 83%, about 82%, about 81%, about 80%, about 75%, about 70%, about 65%, about 60%, about 55%, about 50%, about 45%, about 40%, about 35%, about 30%, about 25%, about 20%, about 15%, about 10%, or about 5% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein comprises about 85% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for about 84% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for about 83% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for about 82% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for about 81% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for about 80% of the combined heterodimeric protein.

[0170] In some embodiments, the XENP32803 protein comprises about 95%, about 90%, about 85%, about 80%, about 75%, about 70%, about 75%, about 70%, about 65%, about 55%, about 50%, about 45%, about 40%, about 35%, about 30%, about 25%, about 20%, about 19%, about 18%, about 17%, about 16%, about 15%, about 14%, about 13%, about 12%, about 11%, about 10%, about 9%, about 8%, about 7%, about 6%, about 5%, about 4%, about 3%, about 2% or about 1% of the combined heterodimeric protein. In some embodiments, the XENP32803 protein comprises about 15% of the combined heterodimeric protein. In some embodiments, the XENP32803 protein accounts for about 16% of the combined heterodimeric protein. In some embodiments, the XENP32803 protein accounts for about 17% of the combined heterodimeric protein. In some embodiments, the XENP32803 protein accounts for about 18% of the combined heterodimeric protein. In some embodiments, the XENP32803 protein accounts for about 19% of the combined heterodimeric protein. In some embodiments, the XENP32803 protein accounts for about 20% of the combined heterodimeric protein.

[0171] In some embodiments, the XENP24306 protein accounts for about 50-100%, about 70-95%, about 80-90%, or about 80-85% of the combined heterodimeric protein. In some embodiments of any of the methods described herein, the XENP32803 protein accounts for about 1-50%, about 5-30%, about 10-20%, or about 15-20% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for about 85% of the combined heterodimeric protein, and the XENP32803 protein accounts for about 15% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for about 84% of the combined heterodimeric protein, and the XENP32803 protein accounts for about 16% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for about 83% of the combined heterodimeric protein, and the XENP32803 protein accounts for about 17% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for about 82% of the combined heterodimeric protein, and the XENP32803 protein accounts for about 18% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for about 81% of the combined heterodimeric protein, and the XENP32803 protein accounts for about 19% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for about 80% of the combined heterodimeric protein, and the XENP32803 protein accounts for about 20% of the combined heterodimeric protein.

[0172] In some embodiments, the XENP24306 protein accounts for 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, 90%, 89%, 88%, 87%, 86%, 85%, 84%, 83%, 82%, 81%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, or 5% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for 85% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for 84% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for 83% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein comprises 82% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein comprises 81% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein comprises 80% of the combined heterodimeric protein.

[0173] In some embodiments, the XENP32803 protein comprises 95%, 90%, 85%, 80%, 75%, 70%, 75%, 70%, 65%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2% or 1% of the combined heterodimeric protein. In some embodiments, the XENP32803 protein comprises 15% of the combined heterodimeric protein. In some embodiments, the XENP32803 protein comprises 16% of the combined heterodimeric protein. In some embodiments, the XENP32803 protein comprises 17% of the combined heterodimeric protein. In some embodiments, the XENP32803 protein comprises 18% of the combined heterodimeric protein. In some embodiments, the XENP32803 protein comprises 19% of the combined heterodimeric protein. In some embodiments, the XENP32803 protein comprises 20% of the combined heterodimeric protein.

[0174] In some embodiments, the XENP24306 protein accounts for 50-100%, 70-95%, 80-90%, or 80-85% of the combined heterodimeric protein. In some embodiments of any of the methods described herein, the XENP32803 protein accounts for 1-50%, 5-30%, 10-20%, or 15-20% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for 85% of the combined heterodimeric protein, and the XENP32803 protein accounts for 15% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for 84% of the combined heterodimeric protein, and the XENP32803 protein accounts for 16% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for 83% of the combined heterodimeric protein, and the XENP32803 protein accounts for 17% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for 82% of the combined heterodimeric protein, and the XENP32803 protein accounts for 18% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for 81% of the combined heterodimeric protein, and the XENP32803 protein accounts for 19% of the combined heterodimeric protein. In some embodiments, the XENP24306 protein accounts for 80% of the combined heterodimeric protein, and the XENP32803 protein accounts for 20% of the combined heterodimeric protein. [Table 2] TIFF2024527047000006.tif183170TIFF2024527047000007.tif183170TIFF2024527047 000008.tif174170TIFF2024527047000009.tif183170TIFF2024527047000010.tif92170

[0175] In one aspect, the present disclosure provides a method of treating hematological cancer in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of any of the heterodimeric proteins described herein or any combination thereof.

[0176] In another aspect, the disclosure provides any of the heterodimeric proteins described herein, or any combination thereof, for use in treating a hematological cancer in a subject in need thereof.

[0177] In another aspect, the present disclosure provides for the use of a therapeutically effective amount of any of the heterodimeric proteins described herein, or any combination thereof, in the manufacture of a medicament for treating a hematological cancer in a subject in need thereof.

[0178] Hematological cancer refers to abnormal or excessive production of blood cells (e.g., white blood cells). Examples of hematological cancers treated by the methods and uses described herein include, but are not limited to, leukemia, lymphoma, and myeloma. More specific non-limiting examples of such hematological cancers include acute myeloid leukemia, adult acute lymphoblastic leukemia, chronic lymphocytic leukemia, non-Hodgkin's lymphoma, B-cell non-Hodgkin's lymphoma, and multiple myeloma. In some embodiments, the hematological cancer is relapsed or refractory. In some embodiments, the hematological cancer is selected from the group consisting of leukemia, acute myeloid leukemia, adult acute lymphoblastic leukemia, chronic lymphocytic leukemia, lymphoma, non-Hodgkin's lymphoma, B-cell non-Hodgkin's lymphoma, and multiple myeloma. In some embodiments, the hematological cancer is selected from the group consisting of leukemia, acute myeloid leukemia, adult acute lymphoblastic leukemia, chronic lymphocytic leukemia. In some embodiments, the hematological cancer is selected from the group consisting of lymphoma, non-Hodgkin's lymphoma, and B-cell non-Hodgkin's lymphoma. In some embodiments, the hematological cancer is leukemia. In some embodiments, the hematological cancer is acute myeloid leukemia. In some embodiments, the hematological cancer is adult acute lymphoblastic leukemia. In some embodiments, the hematological cancer is chronic lymphocytic leukemia. In some embodiments, the hematological cancer is lymphoma. In some embodiments, the hematological cancer is non-Hodgkin's lymphoma. In some embodiments, the hematological cancer is B-cell non-Hodgkin's lymphoma. In some embodiments, the hematological cancer is multiple myeloma. In some embodiments, the hematological cancer is relapsed or refractory multiple myeloma. In some embodiments, the hematological cancer is a hematological cancer for which no standard of care exists, has proven ineffective or intolerable, or is considered inappropriate, or for which clinical trials of investigational drugs are the recognized standard of care.

[0179] In some embodiments, a combination of two or more (e.g., 2, 3, 4, 5, 6, etc.) heterodimeric proteins is used in the methods described herein. In some embodiments, a combination of a first heterodimeric protein and a second heterodimeric protein is administered to a subject.

[0180] In some embodiments, the first heterodimeric protein comprises a first monomer comprising the amino acid sequence set forth in SEQ ID NO:9 and a second monomer comprising the amino acid sequence set forth in SEQ ID NO:10, and the second heterodimeric protein comprises a first monomer comprising the amino acid sequence set forth in SEQ ID NO:9 and a second monomer comprising the amino acid sequence set forth in SEQ ID NO:16.

[0181] In some embodiments, the first heterodimeric protein comprises about 99%, about 98%, about 97%, about 96%, about 95%, about 94%, about 93%, about 92%, about 91%, about 90%, about 89%, about 88%, about 87%, about 86%, about 85%, about 84%, about 83%, about 82%, about 81%, about 80%, about 75%, about 70%, about 65%, about 60%, about 55%, about 50%, about 45%, about 40%, about 35%, about 30%, about 25%, about 20%, about 15%, about 10%, or about 5% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein comprises about 85% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for about 84% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for about 83% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for about 82% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for about 81% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for about 80% of the combined heterodimeric protein.

[0182] In some embodiments, the second heterodimeric protein accounts for about 95%, about 90%, about 85%, about 80%, about 75%, about 70%, about 75%, about 70%, about 65%, about 55%, about 50%, about 45%, about 40%, about 35%, about 30%, about 25%, about 20%, about 19%, about 18%, about 17%, about 16%, about 15%, about 14%, about 13%, about 12%, about 11%, about 10%, about 9%, about 8%, about 7%, about 6%, about 5%, about 4%, about 3%, about 2%, or about 1% of the combination. In some embodiments, the second heterodimeric protein accounts for about 15% of the combined heterodimeric protein. In some embodiments, the second heterodimeric protein accounts for about 16% of the combined heterodimeric protein. In some embodiments, the second heterodimeric protein accounts for about 17% of the combined heterodimeric protein. In some embodiments, the second heterodimeric protein accounts for about 18% of the combined heterodimeric protein. In some embodiments, the second heterodimeric protein accounts for about 19% of the combined heterodimeric protein. In some embodiments, the second heterodimeric protein accounts for about 20% of the combined heterodimeric protein.

[0183] In some embodiments, the first heterodimeric protein accounts for about 50 to about 100%, about 70 to about 95%, about 80 to about 90%, or about 80 to about 85% of the combined heterodimeric protein. In some embodiments of any of the methods described herein, the second heterodimeric protein accounts for about 1 to about 50%, about 5 to about 30%, about 10 to about 20%, or about 15 to about 20% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for about 85% of the combined heterodimeric protein and the second heterodimeric protein accounts for about 15% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for about 84% of the combined heterodimeric protein and the second heterodimeric protein accounts for about 16% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for about 83% of the combined heterodimeric protein, and the second heterodimeric protein accounts for about 17% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for about 82% of the combined heterodimeric protein, and the second heterodimeric protein accounts for about 18% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for about 81% of the combined heterodimeric protein, and the second heterodimeric protein accounts for about 19% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for about 80% of the combined heterodimeric protein, and the second heterodimeric protein accounts for about 20% of the combined heterodimeric protein.

[0184] In some embodiments, the first heterodimeric protein accounts for 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, 90%, 89%, 88%, 87%, 86%, 85%, 84%, 83%, 82%, 81%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, or 5% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for 85% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for 84% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for 83% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for 82% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for 81% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for 80% of the combined heterodimeric protein.

[0185] In some embodiments, the second heterodimeric protein accounts for 95%, 90%, 85%, 80%, 75%, 70%, 75%, 70%, 65%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2% or 1% of the combination. In some embodiments, the second heterodimeric protein accounts for 15% of the combined heterodimeric proteins. In some embodiments, the second heterodimeric protein accounts for 16% of the combined heterodimeric proteins. In some embodiments, the second heterodimeric protein accounts for 17% of the combined heterodimeric proteins. In some embodiments, the second heterodimeric protein accounts for 18% of the combined heterodimeric protein. In some embodiments, the second heterodimeric protein accounts for 19% of the combined heterodimeric protein. In some embodiments, the second heterodimeric protein accounts for 20% of the combined heterodimeric protein.

[0186] In some embodiments, the first heterodimeric protein accounts for 50-100%, 70-95%, 80-90%, or 80-85% of the combined heterodimeric protein. In some embodiments of any of the methods described herein, the second heterodimeric protein accounts for 1-50%, 5-30%, 10-20%, or 15-20% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for 85% of the combined heterodimeric protein and the second heterodimeric protein accounts for 15% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for 84% of the combined heterodimeric protein and the second heterodimeric protein accounts for 16% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for 83% of the combined heterodimeric protein, and the second heterodimeric protein accounts for 17% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for 82% of the combined heterodimeric protein, and the second heterodimeric protein accounts for 18% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for 81% of the combined heterodimeric protein, and the second heterodimeric protein accounts for 19% of the combined heterodimeric protein. In some embodiments, the first heterodimeric protein accounts for 80% of the combined heterodimeric protein, and the second heterodimeric protein accounts for 20% of the combined heterodimeric protein.

[0187] In some embodiments, the first heterodimeric protein and the second heterodimeric protein are administered simultaneously. In some embodiments, the first heterodimeric protein and the second heterodimeric protein are administered sequentially. In some embodiments, the first heterodimeric protein is administered before the second heterodimeric protein. In some embodiments, the second heterodimeric protein is administered before the first heterodimeric protein. In some embodiments, the first heterodimeric protein and the second heterodimeric protein are administered in the same composition. In some embodiments, the first heterodimeric protein and the second heterodimeric protein are administered in separate compositions.

[0188] The methods and uses described herein include administering to a subject a therapeutically effective amount of any of the heterodimeric proteins described herein, or a combination thereof, or a composition described herein, to produce such an effect. Identification of a subject in need of such treatment may be at the discretion of the subject or a medical professional, and may be subjective (e.g., opinion) or objective (e.g., measurable by a test or diagnostic method). Such treatment is suitably administered to a subject suffering from, having, susceptible to, or at risk for hematological cancer.

[0189] In another aspect, the present disclosure provides a method for the detection of CD8 + Provided is a method of inducing the proliferation of effector memory T cells, comprising administering to a subject an effective amount of any of the heterodimeric proteins described herein or any combination thereof.

[0190] In another aspect, the present disclosure provides a method of inducing proliferation of NK cells in a subject suffering from a hematological cancer, comprising administering to the subject an effective amount of any of the heterodimeric proteins described herein or any combination thereof.

[0191] In another aspect, the disclosure provides a method of inducing proliferation of NK cells in a subject suffering from a hematological cancer, comprising administering to the subject an effective amount of any of the heterodimeric proteins described herein or any combination thereof, wherein a proliferative response of the NK cells is greater than or equal to CD8 upon administration of an effective amount of any of the heterodimeric proteins described herein or any combination thereof. + The present invention provides a method for increasing the proliferation response of effector memory T cells.

[0192] In another aspect, the present disclosure provides a method for the detection of CD8 + Provided is a method of inducing proliferation of effector memory T cells and NK cells, comprising administering to a subject an effective amount of any of the heterodimeric proteins described herein or any combination thereof. In some embodiments, upon administration of an effective amount of any of the heterodimeric proteins described herein or any combination thereof, a proliferation response of NK cells is induced by CD8 + The proliferative response of effector memory T cells is stronger.

[0193] In another aspect, the present disclosure provides a method for the detection of CD4 + Provided is a method of inducing the proliferation of effector memory T cells, comprising administering to a subject an effective amount of any of the heterodimeric proteins described herein or any combination thereof.

[0194] In another aspect, the present disclosure provides a method for inducing IFNγ production in a subject suffering from a hematological cancer, comprising administering to the subject an effective amount of any of the heterodimeric proteins described herein or any combination thereof.

[0195] The heterodimeric proteins (or combinations thereof) can be administered parenterally. In some embodiments, the parenteral administration is intravenous administration.

[0196] In some embodiments, the heterodimeric protein of the present disclosure is administered systemically. In some embodiments, the heterodimeric protein is administered as a composition comprising a pharma- ceutically acceptable buffer. Suitable carriers and their formulations are described, for example, in Remington's Pharmaceutical Sciences by EW Martin. In some embodiments, the heterodimeric protein is provided in a dosage form suitable for parenteral (e.g., intravenous) administration route.

[0197] The composition comprising the heterodimeric protein may be provided in unit dosage form (e.g., single-dose ampoules, syringes or bags). In some embodiments, the heterodimeric protein is provided in a vial containing multiple doses. Suitable preservatives may be added to the composition (see below). The composition may be in the form of a solution, suspension, emulsion, infusion device, or delivery device for implantation, or presented as a dry powder to be reconstituted with water or another suitable vehicle before use. Apart from the heterodimeric protein described herein, the composition may comprise suitable acceptable carriers and / or additives. In some embodiments, the composition is suitable for parenteral administration. One or more heterodimeric proteins may be incorporated into microspheres, microcapsules, nanoparticles, or liposomes, etc., for controlled release. In addition, the composition may comprise a suspending agent, a solubilizing agent, a stabilizer, a pH adjusting agent, an isotonicity adjusting agent, and / or a dispersing agent.

[0198] The pharmaceutical composition containing the heterodimeric protein may be in a form suitable for sterile injection. To prepare such a composition, the protein is dissolved or suspended in a parenterally acceptable liquid vehicle. Acceptable vehicles and solvents that can be used include water, water adjusted to a suitable pH by adding an appropriate amount of hydrochloric acid, sodium hydroxide or a suitable buffer, 1,3-butanediol, Ringer's solution, and isotonic saline and dextrose solution. Aqueous formulations may contain one or more preservatives (e.g., methyl, ethyl or n-propyl p-hydroxybenzoate).

[0199] The amount of the heterodimeric protein of the present disclosure administered varies depending on the mode of administration, the age and weight of the patient, and the clinical symptoms of the cancer being treated. The dosage for humans can be determined by extrapolating from the amount of protein used in mice or non-human primates. In certain embodiments, the dosage can vary between about 0.0001 mg protein / kg body weight to about 5 mg protein / kg body weight, or about 0.001 mg / kg body weight to about 4 mg / kg body weight, or about 0.005 mg / kg body weight to about 1 mg / kg body weight, or about 0.005 mg / kg body weight to about 0.3 mg / kg body weight, or about 0.005 mg / kg body weight to about 0.2 mg / kg body weight, or about 0.005 mg / kg body weight to about 0.02 mg / kg body weight. In some embodiments, the dose is about 0.0001, about 0.00025, about 0.0003, about 0.0005, about 0.001, about 0.003, about 0.005, about 0.008, about 0.01, about 0.015, about 0.02, about 0.03, about 0.04, about 0.05, about 0.06, about 0.07, about 0.08, about 0.09, about 0.1, about 0.12, about 0.135, about 0.15, about 0.16, about 0.2, about 0.2025, about 0.24, about 0.25, about about 0.3, about 0.32, about 0.35, about 0.4, about 0.45, about 0.5, about 0.55, about 0.6, about 0.65, about 0.7, about 0.75, about 0.8, about 0.85, about 0.9, about 0.95, about 1, about 1.1, about 1.15, about 1.2, about 1.25, about 1.3, about 1.35, about 1.4, about 1.45, about 1.5, about 1.6, about 1.7, about 1.8, about 1.9, about 2, about 2.5, about 3, about 3.5, about 4, about 4.5, or about 5 mg / kg of body weight. In some embodiments, the dosage is about 0.0025 mg / kg, about 0.005 mg / kg, about 0.01 mg / kg, about 0.015 mg / kg, about 0.02 mg / kg, about 0.025 mg / kg, about 0.03 mg / kg, about 0.04 mg / kg, about 0.05 mg / kg, about 0.06 mg / kg, about 0.08 mg / kg, about 0.1 mg / kg, about 0.12 mg / kg, about 0.16 mg / kg, about 0.2 mg / kg, about 0.24 mg / kg, and about 0.32 mg / kg body weight. In some embodiments, the dosage is about 0.0025 mg / kg body weight. In some embodiments, the dosage is about 0.01 mg / kg body weight.In some embodiments, the dosage is about 0.015 mg / kg body weight. In some embodiments, the dosage is about 0.02 mg / kg body weight. In some embodiments, the dosage is about 0.03 mg / kg body weight. In some embodiments, the dosage is about 0.04 mg / kg body weight. In some embodiments, the dosage is about 0.06 mg / kg body weight. In some embodiments, the dosage is about 0.08 mg / kg body weight. In some embodiments, the dosage is about 0.09 mg / kg body weight. In some embodiments, the dosage is about 0.12 mg / kg body weight. In some embodiments, the dosage is about 0.135 mg / kg body weight. In some embodiments, the dosage is about 0.16 mg / kg body weight. In some embodiments, the dosage is about 0.2025 mg / kg body weight. In some embodiments, the dosage is about 0.24 mg / kg body weight. In some embodiments, the dosage is about 0.32 mg / kg body weight. In some embodiments, the heterodimeric proteins of the present disclosure are administered by IV infusion according to these dosages.

[0200] In certain embodiments, the dosage may vary between 0.0001 mg protein / kg body weight and 5 mg protein / kg body weight, or between 0.001 mg / kg body weight and 4 mg / kg body weight, or between 0.005 mg / kg body weight and 1 mg / kg body weight, or between 0.005 mg / kg body weight and 0.3 mg / kg body weight, or between 0.005 mg / kg body weight and 0.2 mg / kg body weight, or between 0.005 mg / kg body weight and 0.02 mg / kg body weight. In some embodiments, the dosage may vary between 0.0001, 0.0003, 0.0005, 0.001, 0.003, 0.005, 0.008, 0.01, 0.015, 0.02, 0.03, 0.05, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, It can be 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.5, 3, 3.5, 4, 4.5, or 5 mg / kg body weight. In some embodiments, the dose is selected from the group consisting of 0.0025 mg / kg, 0.005 mg / kg, 0.01 mg / kg, 0.015 mg / kg, 0.02 mg / kg, 0.025 mg / kg, 0.03 mg / kg, 0.04 mg / kg, 0.05 mg / kg, 0.06 mg / kg, 0.08 mg / kg, 0.09 mg / kg, 0.10 mg / kg, 0.12 mg / kg, 0.135 mg / kg, 0.16 mg / kg, 0.20 mg / kg, 0.2025 mg / kg, 0.24 mg / kg, and 0.32 mg / kg body weight. In some embodiments, the dose is 0.0025 mg / kg body weight. In some embodiments, the dose is 0.01 mg / kg body weight. In some embodiments, the dose is 0.015 mg / kg body weight. In some embodiments, the dose is 0.02 mg / kg body weight. In some embodiments, the dosage is 0.03 mg / kg body weight. In some embodiments, the dosage is 0.04 mg / kg body weight. In some embodiments, the dosage is 0.06 mg / kg body weight. In some embodiments, the dosage is 0.08 mg / kg body weight. In some embodiments, the dosage is 0.09 mg / kg body weight.In some embodiments, the dosage is 0.12 mg / kg body weight. In some embodiments, the dosage is 0.135 mg / kg body weight. In some embodiments, the dosage is 0.16 mg / kg body weight. In some embodiments, the dosage is 0.2025 mg / kg body weight. In some embodiments, the dosage is 0.24 mg / kg body weight. In some embodiments, the dosage is 0.32 mg / kg body weight. In some embodiments, the heterodimeric proteins of the present disclosure are administered by IV infusion according to these dosage amounts.

[0201] In certain embodiments, the dosage of the heterodimeric protein combination may vary from about 0.0001 mg protein / kg body weight to about 5 mg protein / kg body weight, or from about 0.001 mg / kg body weight to about 4 mg / kg body weight, or from about 0.005 mg / kg body weight to about 1 mg / kg body weight, or from about 0.005 mg / kg body weight to about 0.3 mg / kg body weight, or from about 0.005 mg / kg body weight to about 0.2 mg / kg body weight, or from about 0.005 mg / kg body weight to about 0.02 mg / kg body weight. In some embodiments, the dose is about 0.0001, about 0.0003, about 0.0005, about 0.001, about 0.003, about 0.005, about 0.008, about 0.01, about 0.015, about 0.02, about 0.03, about 0.05, about 0.08, about 0.1, about 0.15, about 0.2, about 0.25, about 0.3, about 0.35, about 0.4, about 0.45, about 0.5, about 0.5 about 1.5, about 0.6, about 0.65, about 0.7, about 0.75, about 0.8, about 0.85, about 0.9, about 0.95, about 1, about 1.1, about 1.15, about 1.2, about 1.25, about 1.3, about 1.35, about 1.4, about 1.45, about 1.5, about 1.6, about 1.7, about 1.8, about 1.9, about 2, about 2.5, about 3, about 3.5, about 4, about 4.5, or about 5 mg / kg of body weight. In some embodiments, the dosage is about 0.0025 mg / kg, about 0.005 mg / kg, about 0.01 mg / kg, about 0.015 mg / kg, about 0.02 mg / kg, about 0.025 mg / kg, about 0.03 mg / kg, about 0.04 mg / kg, about 0.05 mg / kg, about 0.06 mg / kg, about 0.08 mg / kg, about 0.10 mg / kg, about 0.12 mg / kg, about 0.16 mg / kg, about 0.20 mg / kg, about 0.24 mg / kg, and about 0.32 mg / kg body weight. In some embodiments, the dosage is about 0.0025 mg / kg body weight. In some embodiments, the dosage is about 0.01 mg / kg body weight. In some embodiments, the dosage is about 0.015 mg / kg body weight. In some embodiments, the dosage is about 0.02 mg / kg body weight. In some embodiments, the dosage is about 0.03 mg / kg body weight. In some embodiments, the dosage is about 0.04 mg / kg body weight. In some embodiments, the dosage is about 0.06 mg / kg body weight.In some embodiments, the dosage is about 0.08 mg / kg body weight. In some embodiments, the dosage is about 0.09 mg / kg body weight. In some embodiments, the dosage is about 0.12 mg / kg body weight. In some embodiments, the dosage is about 0.135 mg / kg body weight. In some embodiments, the dosage is about 0.16 mg / kg body weight. In some embodiments, the dosage is about 0.2025 mg / kg body weight. In some embodiments, the dosage is about 0.24 mg / kg body weight. In some embodiments, the dosage is about 0.32 mg / kg body weight. In some embodiments, the heterodimeric protein combinations of the present disclosure are administered by IV infusion according to these dosage amounts.

[0202] In certain embodiments, the dosage of the heterodimeric protein combination may vary between 0.0001 mg protein / kg body weight to 5 mg protein / kg body weight, or 0.001 mg / kg body weight to 4 mg / kg body weight, or 0.005 mg / kg body weight to 1 mg / kg body weight, or 0.005 mg / kg body weight to 0.3 mg / kg body weight, or 0.005 mg / kg body weight to 0.2 mg / kg body weight, or 0.005 mg / kg body weight to 0.02 mg / kg body weight. In some embodiments, the dose is 0.0001, 0.0003, 0.0005, 0.001, 0.003, 0.005, 0.008, 0.01, 0.015, 0.02, 0.03, 0.05, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, It can be 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.5, 3, 3.5, 4, 4.5, or 5 mg / kg body weight. In some embodiments, the dosage is 0.0025 mg / kg, 0.005 mg / kg, 0.01 mg / kg, 0.015 mg / kg, 0.02 mg / kg, 0.025 mg / kg, 0.03 mg / kg, 0.04 mg / kg, 0.05 mg / kg, 0.06 mg / kg, 0.08 mg / kg, 0.10 mg / kg, 0.12 mg / kg, 0.16 mg / kg, 0.20 mg / kg, 0.24 mg / kg, and 0.32 mg / kg body weight. In some embodiments, the dosage is 0.0025 mg / kg body weight. In some embodiments, the dosage is 0.01 mg / kg body weight. In some embodiments, the dosage is 0.015 mg / kg body weight. In some embodiments, the dosage is 0.02 mg / kg body weight. In some embodiments, the dosage is 0.03 mg / kg body weight. In some embodiments, the dosage is 0.04 mg / kg body weight. In some embodiments, the dosage is 0.06 mg / kg body weight. In some embodiments, the dosage is 0.08 mg / kg body weight. In some embodiments, the dosage is 0.09 mg / kg body weight. In some embodiments, the dosage is 0.12 mg / kg body weight.In some embodiments, the dosage is 0.135 mg / kg body weight. In some embodiments, the dosage is 0.16 mg / kg body weight. In some embodiments, the dosage is 0.2025 mg / kg body weight. In some embodiments, the dosage is 0.24 mg / kg body weight. In some embodiments, the dosage is 0.32 mg / kg body weight. In some embodiments, the heterodimeric protein combinations of the present disclosure are administered by IV infusion according to these dosage amounts.

[0203] In some embodiments, the heterodimeric proteins of the present disclosure, or combinations thereof, are administered daily, i.e., every 24 hours. In some embodiments, the heterodimeric proteins or combinations thereof are administered weekly, i.e., once a week (Q1W). In some embodiments, the heterodimeric proteins or combinations thereof are administered once every two weeks, i.e., once every 14 days (Q2W). In some embodiments, the heterodimeric proteins or combinations thereof are administered once every three weeks, i.e., once every 21 days (Q3W). In some embodiments, the heterodimeric proteins or combinations thereof are administered once every four weeks, i.e., once every 28 days (Q4W). In some embodiments, the heterodimeric proteins or combinations thereof are administered once every five weeks (Q5W). In some embodiments, the heterodimeric proteins or combinations thereof are administered once every six weeks (Q6W). In some embodiments, the heterodimeric proteins or combinations thereof are administered once every seven weeks (Q7W). In some embodiments, the heterodimeric proteins or combinations thereof are administered once every 8 weeks (Q8W). In some embodiments, the heterodimeric proteins or combinations thereof are administered once every 9 weeks (Q9W). In some embodiments, the heterodimeric proteins or combinations thereof are administered once every 10 weeks (Q10W). In some embodiments, the heterodimeric proteins or combinations thereof are administered once every 11 weeks (Q11W). In some embodiments, the heterodimeric proteins or combinations thereof are administered once every 12 weeks (Q12W). In some embodiments, the heterodimeric proteins or combinations thereof are administered once per month. In some embodiments, the heterodimeric proteins or combinations thereof are administered once per 2 months. In some embodiments, the heterodimeric proteins or combinations thereof are administered once per 3 months. In some embodiments, the heterodimeric proteins or combinations thereof are administered once per 4 months.In some embodiments, the heterodimeric proteins or combinations thereof are administered once every 5 months. In some embodiments, the heterodimeric proteins or combinations thereof are administered once every 6 months. In some embodiments, the heterodimeric proteins or combinations thereof are administered once every 7 months. In some embodiments, the heterodimeric proteins or combinations thereof are administered once every 8 months. In some embodiments, the heterodimeric proteins or combinations thereof are administered once every 9 months. In some embodiments, the heterodimeric proteins or combinations thereof are administered once every 10 months. In some embodiments, the heterodimeric proteins or combinations thereof are administered once every 11 months. In some embodiments, the heterodimeric proteins or combinations thereof are administered once every 12 months. In some embodiments, the heterodimeric proteins or combinations thereof are administered once a year. In some embodiments, the heterodimeric proteins or combinations of the present disclosure are administered by IV infusion according to the frequencies described herein.

[0204] In some embodiments, the heterodimeric protein of the present disclosure or combination thereof is administered at any of the above frequencies for one or more cycles. In some embodiments, the heterodimeric protein of the present disclosure or combination thereof is administered at any of the above frequencies for one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen, seventeen, eighteen, nineteen, or twenty cycles. In some embodiments, the heterodimeric protein of the present disclosure or combination thereof is administered at a frequency of Q1W for one or more cycles. In some embodiments, the heterodimeric protein of the present disclosure or combination thereof is administered at a frequency of Q1W for one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen, seventeen, eighteen, nineteen, or twenty cycles. In some embodiments, the heterodimeric protein of the present disclosure or combination thereof is administered at a frequency of Q2W for one or more cycles. In some embodiments, the heterodimeric proteins of the present disclosure or combinations thereof are administered at a frequency of Q2W for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 cycles. In some embodiments, the heterodimeric proteins of the present disclosure or combinations thereof are administered at a frequency of Q3W for one or more cycles. In some embodiments, the heterodimeric proteins of the present disclosure or combinations thereof are administered at a frequency of Q3W for one or more cycles. In some embodiments, the heterodimeric proteins of the present disclosure or combinations thereof are administered at a frequency of Q4W for one or more cycles. In some embodiments, the heterodimeric proteins of the present disclosure or combinations thereof are administered at a frequency of Q4W for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 cycles.

[0205] In some embodiments, the subject has previously been administered one or more treatments or agents for the treatment of hematological cancer. In some embodiments, the subject has previously been administered one treatment. In some embodiments, the subject has previously been administered two treatments. In some embodiments, the subject has previously been administered three treatments. In some embodiments, the subject has previously been administered four treatments. In some embodiments, the subject has previously been administered five treatments. In some embodiments, the previous treatment administered to the subject is an immunomodulatory agent, a proteasome inhibitor, an anti-CD38 monoclonal antibody, or a combination thereof. In some aspects, the previous treatment administered to the subject is an immunomodulatory agent. In some embodiments, the immunomodulatory agent is selected from the group consisting of lenalidomide, thalidomide, and pomalidomide. In some embodiments, the immunomodulatory agent is lenalidomide. In some aspects, the immunomodulatory agent is thalidomide. In some aspects, the immunomodulatory agent is pomalidomide. In some aspects, the previous treatment administered to the subject is a proteasome inhibitor. In some embodiments, the proteasome inhibitor is selected from the group consisting of bortezomib, carfilzomib, and ixazomib. In some embodiments, the proteasome inhibitor is selected from the group consisting of bortezomib. In some embodiments, the proteasome inhibitor is selected from the group consisting of carfilzomib. In some embodiments, the proteasome inhibitor is selected from the group consisting of ixazomib. In some embodiments, the previous treatment administered to the subject is an anti-CD38 monoclonal antibody. In some embodiments, the anti-CD38 antibody is selected from the group consisting of daratumumab, isatuximab, mezagitamab (TAK-079), and felzalutamab (MOR202). In some embodiments, the anti-CD38 monoclonal antibody is daratumumab. In some embodiments, the anti-CD38 monoclonal antibody is isatuximab. In some embodiments, the anti-CD38 antibody is mezagitamab. In some embodiments, the anti-CD38 antibody is felzalutamab.

[0206] Methods of treatment with IL15-IL15Rα heterodimeric Fc fusion protein and anti-CD38 antibody as combination therapy Another aspect of the present disclosure provides a method of treating a hematological cancer described herein in a subject in need thereof, comprising administering to the subject an effective amount of (a) any of the heterodimeric proteins described herein (i.e., IL15-IL15Rα heterodimeric Fc fusion proteins) or a combination thereof, and (b) an anti-CD38 antibody or antigen-binding fragment thereof. In some embodiments, the anti-CD38 antibody is a monoclonal antibody. The heterodimeric protein may be administered according to any of the methods described herein. The heterodimeric protein may be administered in any of the compositions described herein.

[0207] In some embodiments, two or more of the heterodimeric proteins described herein are administered to a subject. In some embodiments, three or more of the heterodimeric proteins described herein are administered to a subject. In some embodiments, four or more of the heterodimeric proteins described herein are administered to a subject. In some embodiments, five or more of the heterodimeric proteins described herein are administered to a subject.

[0208] In some embodiments, a combination of a first heterodimeric protein and a second heterodimeric protein is administered to a subject. In some embodiments, the first heterodimeric protein comprises a first monomer comprising the amino acid sequence shown in SEQ ID NO:9 and a second monomer comprising the amino acid sequence shown in SEQ ID NO:10, and the second heterodimeric protein comprises a first monomer comprising the amino acid sequence shown in SEQ ID NO:9 and a second monomer comprising the amino acid sequence shown in SEQ ID NO:16.

[0209] Cluster of differentiation 38 (CD38) is a type II transmembrane glycoprotein expressed on various hematopoietic and non-hematopoietic tissues and cells. The expression level of CD38 on hematopoietic cells changes during the stages of cell maturation and activation. Tumor cells (e.g., leukemia cells and multiple myeloma cells) express CD38 at higher levels compared to normal lymphoid and myeloid cells. Overexpression of CD38 is associated with poor prognosis in patients with several hematological cancers. Disruption of the CD38 pathway is an attractive strategy to reactivate tumor-specific T-cell immunity, and indeed, multiple inhibitors of CD38 have demonstrated clinical efficacy or promising antitumor activity in a wide range of tumor types, including multiple myeloma and chronic lymphocytic leukemia, leading to the approval of several anti-CD38 antibodies (e.g., daratumumab, isatuximab, mezagitamab (TAK-079) and felzalutamab (MOR202)) for the treatment of selected indications to date.

[0210] Antibodies that specifically bind to CD38 are known in the art and are described, for example, in de Weers et al. J Immunol. 2011; 186(3):1840-1848, Martin et al. Blood; 126(23):509, Fedyk et al. British J. of Clin.Pharm.2020;86(7):1314-1325, Boxhammer et al.Blood.2015;126(23):3015; WO 2006 / 099875, WO 2011 / 154453, WO 2008 / 047242, WO 2007 / 042309, WO 2012 / 092612, WO 2012 / 092616, WO 2019 / 186273, U.S. Patent No. 7,829,673, U.S. Patent No. 9,187 ,565, U.S. Patent No. 9,249,226, U.S. Patent No. 9,944,711, U.S. Patent No. 8,153,765, U.S. Patent No. 8,263,746B2, U.S. Patent No. 9,758,590, U.S. Patent No. 8,088,896, U.S. Patent No. 8,486,894B2, U.S. Patent No. 9,193,799, U.S. Patent No. 10,184,005, U.S. Patent No. 9,102,744, U.S. Patent No. 8,362,211, U.S. Patent No. 8,926,969, U.S. Patent No. 9,790,285, U.S. Patent No. US Patent No. 9,676,869, US Patent No. 10,336,833, US Patent No. 10,494,444, US Patent Application Publication No. 2009 / 0148449, US Patent Application Publication No. 2011 / 0099647, US Patent Application Publication No. 2020 / 0283542, US Patent Application Publication No. 2013 / 0209355, US Patent Application Publication No. 2016 / 0237161, US Patent Application Publication No. 2009 / 0304710, US Patent Application Publication No. 2020 / 0408765, US Patent Application Publication No. No. 2010 / 0285004, U.S. Patent Application Publication No. 2011 / 0268726, U.S. Patent Application Publication No. 2016 / 0096901, U.S. Patent Application Publication No. 2009 / 0252733, U.S. Patent Application Publication No. 2012 / 0052078, U.S. Patent Application Publication No. 2013 / 273072, U.S. Patent Application Publication No. 2016 / 0075796, U.S. Patent Application Publication No. 2019 / 0077877, U.S. Patent Application Publication No. 2014 / 0155584, U.S. Patent Application Publication No. 2012 / 0201827,U.S. Patent Application Publication No. 2013 / 0171154, U.S. Patent Application Publication No. 2015 / 0203587, U.S. Patent Application Publication No. 2015 / 0291702, U.S. Patent Application Publication No. 2018 / 0016349, U.S. Patent Application Publication No. 2018 / 0066069, U.S. Patent Application Publication No. 2020 / 0031951, U.S. Patent Application Publication No. 2020 / 0040105, European Patent Application Publication No. 1866338, European Patent Application Publication No. 2567976, European Patent Application Publication No. 2020 / 0040105 ... and EP 3153525, EP 2580243, EP 3613774, EP 3498735, EP 2860192, EP 3284755, EP 3284754, EP 3798231, EP 2658870, EP 3789404, and EP 2648871. Examples of anti-CD38 antibodies useful in the methods of the present disclosure include, but are not limited to, daratumumab, isatuximab, mezagitamab (TAK-079), and felzalutamab (MOR202). Daratumumab is an IgGk1 monoclonal anti-CD38 antibody described in WO 2006 / 099875 and de Weers et al., J Immunol. 2011;186(3):1840-1848. Isatuximab is a monoclonal anti-CD38 antibody disclosed in WO 2008 / 047242 and Martin et al., Blood;126(23):509. Mezagitamab is an antibody targeting CD38 described in WO 2012 / 092612, WO 2012 / 092616 and / or WO 2019 / 186273, and Fedyk et al. British J. of Clin. Pharm. 2020;86(7):1314-1325. Felzalutamab is an antibody that targets CD38, as described in U.S. Pat. No. 8,263,746, or WO 2007 / 042309, and Boxhammer et al. Blood. 2015;126(23):3015. In some embodiments, the anti-CD38 antibody is daratumumab. In some embodiments,The anti-CD-38 antibody is isatuximab. In some embodiments, the anti-CD-38 antibody is mezagitamab (TAK-079). In some embodiments, the anti-CD-38 antibody is felzalutamab (MOR202).

[0211] In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered in combination with XENP24306. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered in combination with XENP32803. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered in combination with XENP24306 and XENP32803. In some embodiments, daratumumab is administered in combination with XENP24306. In some embodiments, daratumumab is administered in combination with XENP32803. In some embodiments, daratumumab is administered in combination with XENP24306 and XENP32803. In some embodiments, daratumumab or antigen-binding fragment thereof is administered in combination with XENP24306. In some embodiments, daratumumab or antigen-binding fragment thereof is administered in combination with XENP32803. In some embodiments, daratumumab or an antigen-binding fragment thereof is administered in combination with XENP24306 and XENP32803. In some embodiments, isatuximab is administered in combination with XENP24306. In some embodiments, isatuximab is administered in combination with XENP32803. In some embodiments, isatuximab is administered in combination with XENP24306 and XENP32803. In some aspects, isatuximab or an antigen-binding fragment thereof is administered in combination with XENP24306. In some embodiments, isatuximab or an antigen-binding fragment thereof is administered in combination with XENP32803. In some embodiments, isatuximab or an antigen-binding fragment thereof is administered in combination with XENP24306 and XENP32803. In some embodiments, mezagitamab (TAK-079) is administered in combination with XENP24306. In some embodiments, mezagitamab (TAK-079) is administered in combination with XENP32803. In some embodiments, mezagitamab (TAK-079) is administered in combination with XENP24306 and XENP32803.In some embodiments, mezagitamab (TAK-079) or an antigen-binding fragment thereof is administered in combination with XENP24306. In some embodiments, mezagitamab (TAK-079) or an antigen-binding fragment thereof is administered in combination with XENP32803. In some embodiments, mezagitamab (TAK-079) or an antigen-binding fragment thereof is administered in combination with XENP24306 and XENP32803. In some embodiments, felzalutamab (MOR202) is administered in combination with XENP24306. In some embodiments, felzalutamab (MOR202) is administered in combination with XENP32803. In some embodiments, felzalutamab (MOR202) is administered in combination with XENP24306 and XENP32803. In some embodiments, felzalutamab (MOR202) or an antigen-binding fragment thereof is administered in combination with XENP24306. In some embodiments, felzalutamab (MOR202) or an antigen-binding fragment thereof is administered in combination with XENP32803. In some embodiments, felzalutamab (MOR202) or an antigen-binding fragment thereof is administered in combination with XENP24306 and XENP32803.

[0212] The anti-CD38 antibody or antigen-binding fragment thereof may be administered parenterally. In some embodiments, the parenteral administration is subcutaneous administration. In some embodiments, the parenteral administration is intravenous administration.

[0213] The amount of anti-CD38 antibody or antigen-binding fragment thereof administered in combination with the heterodimeric protein (or combination thereof) of the present disclosure varies depending on the mode of administration, the age and weight of the patient, and the clinical symptoms of the cancer being treated. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered at its approved dosage. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered at less than its approved dosage. A physician will be able to determine the appropriate dosage of the anti-CD38 antibody or antigen-binding fragment thereof for administration in combination with the heterodimeric protein of the present disclosure. In some embodiments, the dosage of the anti-CD38 antibody or antigen-binding fragment thereof is about 1800 mg / 30,000 U of recombinant human PH20 hyaluronidase (rHuPH20). In some embodiments, the dosage of the anti-CD38 antibody or antigen-binding fragment thereof is about 1800 mg / 30,000 U of rHuPH20 weekly. In some embodiments, the dosage of the anti-CD38 antibody or antigen-binding fragment thereof is about 1800 mg / 30,000 U of rHuPH20 every two weeks. In some embodiments, the dosage of the anti-CD38 antibody or antigen-binding fragment thereof is about 1800 mg / 30,000 U of rHuPH20 every three weeks. In some embodiments, the dosage of the anti-CD38 antibody or antigen-binding fragment thereof is about 1800 mg / 30,000 U of rHuPH20 every four weeks. In some embodiments, the dosage of the anti-CD38 antibody or antigen-binding fragment thereof is about 1800 mg / 30,000 U of rHuPH20 every five weeks. In some embodiments, the dosage of the anti-CD38 antibody or antigen-binding fragment thereof is about 1800 mg every week. In some embodiments, the dosage of the anti-CD38 antibody or antigen-binding fragment thereof is about 1800 mg every two weeks. In some embodiments, the dosage of the anti-CD38 antibody or antigen-binding fragment thereof is about 1800 mg every three weeks. In some embodiments, the dosage of the anti-CD38 antibody or antigen-binding fragment thereof is about 1800 mg every 4 weeks. In some embodiments, the dosage of the anti-CD38 antibody or antigen-binding fragment thereof is about 1800 mg every 5 weeks.

[0214] The heterodimeric proteins or combinations thereof described herein may be administered simultaneously or sequentially with the anti-CD38 antibody or antigen-binding fragment thereof. In some embodiments, the heterodimeric proteins or combinations thereof described herein and the anti-CD38 antibody or antigen-binding fragment thereof are administered simultaneously. In some embodiments, the heterodimeric proteins or combinations thereof described herein and the anti-CD38 antibody or antigen-binding fragment thereof are administered sequentially. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered after the heterodimeric protein (or combinations thereof). In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered before the heterodimeric protein (or combinations thereof). In some embodiments, the heterodimeric proteins or combinations thereof described herein and the anti-CD38 antibody or antigen-binding fragment thereof are administered in the same composition. In some embodiments, the heterodimeric proteins or combinations thereof described herein are administered in a separate composition from the anti-CD38 antibody or antigen-binding fragment thereof.

[0215] In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered daily, i.e., every 24 hours. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered weekly, i.e., once a week (Q1W). In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every two weeks, i.e., once every 14 days (Q2W). In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every three weeks, i.e., once every 21 days (Q3W). In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every four weeks, i.e., once every 28 days (Q4W). In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every five weeks (Q5W). In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every six weeks (Q6W). In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every seven weeks (Q7W). In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every 8 weeks (Q8W). In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every 9 weeks (Q9W). In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every 10 weeks (Q10W). In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every 11 weeks (Q11W). In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every 12 weeks (Q12W). In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every month. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every 2 months. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every 3 months. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every 4 months. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every 5 months. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every six months. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every seven months.In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every 8 months. In some embodiments, the CD38 antibody or antigen-binding fragment thereof is administered once every 9 months. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every 10 months. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every 11 months. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every 12 months. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered once every year. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered subcutaneously according to the frequencies described herein.

[0216] In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered for one or more cycles at any of the above frequencies. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered for one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen, seventeen, eighteen, nineteen, or twenty cycles at any of the above frequencies. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered for one or more cycles at a frequency of Q1W. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered for one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen, seventeen, eighteen, nineteen, or twenty cycles at a frequency of Q1W. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered for one or more cycles at a frequency of Q2W. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered at a frequency of Q1W for 4 cycles. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered at a frequency of Q2W for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 cycles. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered at a frequency of Q2W for 8 cycles. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered at a frequency of Q3W for one or more cycles. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered at a frequency of Q3W for one or more cycles. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered at a frequency of Q4W for one or more cycles. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered Q4W at a frequency of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 cycles.

[0217] In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered subcutaneously. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered subcutaneously at a fixed dose on days 1 and 8 of each 14-day cycle. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered subcutaneously at a fixed dose on day 1 of each 14-day cycle. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered subcutaneously at a fixed dose on day 1 of each 28-day cycle. In some embodiments, the heterodimeric protein (or combination thereof) of the present disclosure is administered by intravenous infusion at a fixed dose on day 1 of each 14-day cycle. In some embodiments, the heterodimeric protein (or combination thereof) of the present disclosure is administered by intravenous infusion at a fixed dose on day 2 of each 14-day cycle. In some embodiments, the heterodimeric protein (or combination thereof) of the present disclosure is administered by intravenous infusion at a fixed dose on day 1 of each 28-day cycle. In some embodiments, the heterodimeric proteins of the present disclosure (or combinations thereof) are administered by intravenous infusion at a fixed dose on day 2 of each 28 day cycle.

[0218] In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered subcutaneously at a fixed dose on days 1 and 8 of each 14-day cycle in combination with the heterodimeric protein of the present disclosure. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered subcutaneously at a fixed dose on days 1 and 8 of each 14-day cycle and is administered consecutively with the heterodimeric protein of the present disclosure. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered subcutaneously at a fixed dose on days 1 and 8 of each 14-day cycle and is administered simultaneously with the heterodimeric protein of the present disclosure. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered subcutaneously at a fixed dose on days 1 and 8 of each 14-day cycle in combination with the heterodimeric protein of the present disclosure, which is administered intravenously on day 1 of each 14-day cycle. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered subcutaneously at a fixed dose on days 1 and 8 of each 14-day cycle in combination with a heterodimeric protein of the present disclosure administered intravenously on day 2 of each 14-day cycle. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered subcutaneously at a fixed dose on day 1 of each 14-day cycle in combination with a heterodimeric protein of the present disclosure administered intravenously on day 1 of each 14-day cycle. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered subcutaneously at a fixed dose on day 1 of each 14-day cycle in combination with a heterodimeric protein of the present disclosure administered intravenously on day 2 of each 14-day cycle. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered subcutaneously at a fixed dose on day 1 of each 28-day cycle in combination with a heterodimeric protein of the present disclosure administered intravenously on day 1 of each 28-day cycle. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered subcutaneously at a fixed dose on day 1 of each 28 day cycle in combination with a heterodimeric protein of the present disclosure administered intravenously on day 2 of each 28 day cycle.

[0219] In some embodiments, the heterodimeric protein is administered at a frequency of Q2W and the anti-CD38 antibody or antigen-binding fragment thereof is administered at a frequency of Q1W for one or more cycles. In some embodiments, the heterodimeric protein is administered at a frequency of Q2W and the anti-CD38 antibody or antigen-binding fragment thereof is administered at a frequency of Q2W for one or more cycles. In some embodiments, the heterodimeric protein is administered at a frequency of Q4W and the anti-CD38 antibody or antigen-binding fragment thereof is administered at a frequency of Q4W for one or more cycles.

[0220] In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered at a dose of about 1800 mg on day 1 of each 14-day cycle. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered at a dose of about 1800 mg on days 1 and 8 of each 14-day cycle. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered at a dose of about 1800 mg on day 1 of each 28-day cycle. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered in combination with a heterodimeric protein of the present disclosure at a dose of about 1800 mg on day 1 of each 14-day cycle. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof is administered in combination with a heterodimeric protein of the present disclosure at a dose of about 1800 mg on days 1 and 8 of each 14-day cycle. In some embodiments, the anti-CD38 antibody or antigen-binding fragment thereof in combination with a heterodimeric protein of the present disclosure is administered at a dose of about 1800 mg on day 1 of each 28-day cycle. In some aspects, the anti-CD38 antibody or antigen-binding fragment thereof is administered using an approved dosing regimen.

[0221] In some embodiments, anti-CD38 antibodies are established treatments for cancer, and the addition of heterodimeric protein treatment to the treatment regimen improves the therapeutic effect on the patient. Such improvement can be measured as an increased response per patient or an increased response in a patient population. The heterodimeric proteins or combinations thereof described herein and the anti-CD38 antibodies or antigen-binding fragments thereof can act synergistically. In some embodiments, the heterodimeric proteins or combinations thereof described herein can be administered at a dosage less than their therapeutically effective dose when administered as monotherapy. In some embodiments, the anti-CD38 antibodies or antigen-binding fragments thereof can be administered at a dosage less than their therapeutically effective dose when administered as monotherapy.

[0222] In some embodiments, the subject has previously been administered an agent for treating a hematological cancer. In some embodiments, the subject has previously been administered one or more treatments for the treatment of a hematological cancer. In some embodiments, the subject has previously been administered one treatment. In some embodiments, the subject has previously been administered two treatments. In some embodiments, the subject has previously been administered three treatments. In some embodiments, the subject has previously been administered four treatments. In some embodiments, the subject has previously been administered five treatments. In some embodiments, the previous treatment administered to the subject is an immunomodulatory agent, a proteasome inhibitor, an anti-CD38 monoclonal antibody, or a combination thereof. In some aspects, the previous treatment administered to the subject is an immunomodulatory agent. In some embodiments, the immunomodulatory agent is selected from the group consisting of lenalidomide, thalidomide, and pomalidomide. In some embodiments, the immunomodulatory agent is lenalidomide. In some aspects, the immunomodulatory agent is thalidomide. In some aspects, the immunomodulatory agent is pomalidomide. In some embodiments, the previous treatment administered to the subject is a proteasome inhibitor. In some embodiments, the proteasome inhibitor is selected from the group consisting of bortezomib, carfilzomib, and ixazomib. In some embodiments, the proteasome inhibitor is selected from the group consisting of bortezomib. In some embodiments, the proteasome inhibitor is selected from the group consisting of carfilzomib. In some embodiments, the proteasome inhibitor is selected from the group consisting of ixazomib. In some embodiments, the previous treatment administered to the subject is an anti-CD38 monoclonal antibody. In some embodiments, the anti-CD38 monoclonal antibody is selected from the group consisting of daratumumab, isatuximab, mezagitamab (TAK-079), and felzalutamab (MOR202). In some embodiments, the anti-CD38 monoclonal antibody is daratumumab. In some embodiments, the anti-CD38 monoclonal antibody is isatuximab. In some embodiments, the anti-CD38 monoclonal antibody is mezagitamab.In some embodiments, the anti-CD38 monoclonal antibody is felzalutamab.

[0223] Examples of hematological cancers treated by the combination of the heterodimeric protein of the present disclosure, anti-CD38 antibody or antigen-binding fragment thereof include, but are not limited to, leukemia, lymphoma and myeloma. More specific non-limiting examples of such hematological cancers include acute myeloid leukemia, adult acute lymphoblastic leukemia, chronic lymphocytic leukemia, non-Hodgkin's lymphoma, B-cell non-Hodgkin's lymphoma, and multiple myeloma. In some embodiments, the hematological cancer is relapsed or refractory. In some embodiments, the hematological cancer is selected from the group consisting of leukemia, acute myeloid leukemia, adult acute lymphoblastic leukemia, chronic lymphocytic leukemia, lymphoma, non-Hodgkin's lymphoma, B-cell non-Hodgkin's lymphoma, and multiple myeloma. In some embodiments, the hematological cancer is selected from the group consisting of leukemia, acute myeloid leukemia, adult acute lymphoblastic leukemia, chronic lymphocytic leukemia. In some embodiments, the hematological cancer is selected from the group consisting of lymphoma, non-Hodgkin's lymphoma, and B-cell non-Hodgkin's lymphoma. In some embodiments, the hematological cancer is leukemia. In some embodiments, the hematological cancer is acute myeloid leukemia. In some embodiments, the hematological cancer is adult acute lymphoblastic leukemia. In some embodiments, the hematological cancer is chronic lymphocytic leukemia. In some embodiments, the hematological cancer is lymphoma. In some embodiments, the hematological cancer is non-Hodgkin's lymphoma. In some embodiments, the hematological cancer is B-cell non-Hodgkin's lymphoma. In some embodiments, the hematological cancer is multiple myeloma. In some embodiments, the hematological cancer is relapsed or refractory multiple myeloma. In some embodiments, the hematological cancer is a hematological cancer for which no standard of care exists, has proven ineffective or intolerable, or is considered inappropriate, or for which clinical trials of investigational drugs are the recognized standard of care.

[0224] Combination therapy may also provide improved responses with less frequent doses or less frequent doses of anti-CD38 antibodies or antigen-binding fragments thereof, resulting in better tolerated treatment regimens. For example, combination therapy of heterodimeric proteins with anti-CD38 antibodies or antigen-binding fragments thereof may provide enhanced clinical activity through a variety of mechanisms, including enhanced ADCC, ADCP, and / or NK cell, T cell, neutrophil or monocyte cell levels or immune responses.

[0225] Exemplary embodiments Particular embodiments of the present disclosure are illustrated in the following numbered embodiments. 1. A method of treating a hematological cancer in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a heterodimeric protein, the heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain; and (ii) a second monomer comprising a sushi domain of an IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain, wherein the IL-15 protein comprises an N65D amino acid substitution and one or more amino acid substitutions selected from the group consisting of N4D, D30N, E64Q. 2. CD8 in subjects with hematological cancer +1. A method for inducing proliferation of effector memory T cells, comprising administering to a subject an effective amount of a heterodimeric protein, the heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to an N-terminus of the first Fc domain; and (ii) a second monomer comprising a sushi domain of an IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently linked to an N-terminus of the second Fc domain, wherein the IL-15 protein comprises an N65D amino acid substitution and one or more amino acid substitutions selected from the group consisting of N4D, D30N, and E64Q. 3. A method for inducing proliferation of NK cells in a subject suffering from a hematological cancer, comprising administering to the subject an effective amount of a heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain; and (ii) a second monomer comprising a sushi domain of an IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain, wherein the IL-15 protein comprises an N65D amino acid substitution and one or more amino acid substitutions selected from the group consisting of N4D, D30N, E64Q. 4. CD8 in subjects with hematological cancer +1. A method for inducing proliferation of effector memory T cells and NK cells, comprising administering to a subject an effective amount of a heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to an N-terminus of the first Fc domain; and (ii) a second monomer comprising a sushi domain of an IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently linked to an N-terminus of the second Fc domain, wherein the IL-15 protein comprises an N65D amino acid substitution and one or more amino acid substitutions selected from the group consisting of N4D, D30N, and E64Q. 5. A method for inducing IFNγ production in a subject suffering from a hematological cancer, comprising administering to the subject an effective amount of a heterodimeric protein, the heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain; and (ii) a second monomer comprising a sushi domain of an IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain, wherein the IL-15 protein comprises an N65D amino acid substitution and one or more amino acid substitutions selected from the group consisting of N4D, D30N, and E64Q. 6. The method of any one of embodiments 1-5, wherein the first Fc domain and the second Fc domain each contain the amino acid substitutions E233P, L234V, L235A, G236del and S267K according to EU numbering. 7. The method of any one of embodiments 1-6, wherein the first Fc domain further comprises the amino acid substitutions L368D and K370S according to EU numbering, and the second Fc domain further comprises the amino acid substitutions S364K and E357Q according to EU numbering. 8. The method of any one of embodiments 1-6, wherein the first Fc domain further comprises the amino acid substitutions S364K and E357Q according to EU numbering, and the second Fc domain further comprises the amino acid substitutions L368D and K370S according to EU numbering. 9. The method of any one of embodiments 1-8, wherein the first Fc domain further comprises the amino acid substitutions Q295E, N384D, Q418E and N421D according to EU numbering. 10. The method of any one of embodiments 1 to 8, wherein the second Fc domain further comprises the amino acid substitutions Q295E, N384D, Q418E and N421D according to EU numbering. 11. The method of any one of embodiments 1 to 10, wherein the second Fc domain further comprises the amino acid substitution K246T according to EU numbering. 12. The method of any one of embodiments 1 to 11, wherein the IL-15 protein comprises the amino acid substitutions D30N, E64Q and N65D. 13. The method of any one of embodiments 1 to 12, wherein the IL-15 protein comprises the amino acid sequence shown in SEQ ID NO:5. 14. The method according to any one of the preceding embodiments, wherein the sushi domain of the IL-15Rα protein comprises the amino acid sequence shown in SEQ ID NO:4. 15. The method of any one of embodiments 1 to 14, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain via a first linker. 16. The method of any one of embodiments 1 to 15, wherein the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain via a second linker. 17. The method of any one of embodiments 1 to 16, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain via a first linker, and the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain via a second linker. 18. The method of any one of embodiments 15-17, wherein the first linker and / or the second linker are, independently, a variable length Gly-Ser linker. 19. The method of embodiment 18, wherein the first linker and / or the second linker independently comprise a linker selected from the group consisting of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 39), (Ser-Ser-Ser-Ser-Gly)n (SEQ ID NO: 40), (Gly-Ser-Ser-Gly-Gly)n (SEQ ID NO: 41), and (Gly-Gly-Ser-Gly-Gly)n (SEQ ID NO: 42), where n is an integer from 1 to 5. 20. A method of treating a hematological cancer in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of a heterodimeric protein, the heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain; and (ii) a second monomer comprising an IL-15Rα protein and a second Fc domain, wherein the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain, wherein the first Fc domain and the second Fc domain have the sequence numbers S267K / L368D / K370S:S267K / S364K / E according to EU numbering. 357Q;S364K / E357Q:L368D / K370S;L368D / K370S:S364K;L368E / K370S:S364K;T411E / K360E / Q36 2E:D401K;L368D / K370S:S364K / E357L;K370S:S364K / E357Q;S267K / S364K / E357Q:S267K / L368D / 16. The method of claim 1, comprising a set of amino acid substitutions selected from the group consisting of: K370S; L368D / K370S:S364K / E357Q; S364K:L368D / K370S; S364K:L368E / K370S; D401K:T411E / K360E / Q362E; S364K / E357L:L368D / K370S; and S364K / E357Q:K370S. 21. CD8 in subjects with hematological cancer +1. A method for inducing proliferation of effector memory T cells, comprising administering to a subject an effective amount of a heterodimeric protein, the heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to an N-terminus of the first Fc domain; and (ii) a second monomer comprising an IL-15Rα protein and a second Fc domain, wherein the IL-15Rα protein is covalently linked to an N-terminus of the second Fc domain, wherein the first Fc domain and the second Fc domain have the sequence numbers S267K / L368D / K370S:S267K / S364K / E357Q, according to EU numbering. ;S364K / E357Q:L368D / K370S;L368D / K370S:S364K;L368E / K370S:S364K;T411E / K360E / Q362E: D401K;L368D / K370S:S364K / E357L;K370S:S364K / E357Q;S267K / S364K / E357Q:S267K / L368D / K3 70S; L368D / K370S:S364K / E357Q; S364K:L368D / K370S; S364K:L368E / K370S; D401K:T411E / K360E / Q362E; S364K / E357L:L368D / K370S; and S364K / E357Q:K370S. 22. A method for inducing proliferation of NK cells in a subject suffering from a hematological cancer, comprising administering to the subject an effective amount of a heterodimeric protein, the heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain; and (ii) a second monomer comprising an IL-15Rα protein and a second Fc domain, wherein the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain, wherein the first Fc domain and the second Fc domain have the sequence S267K / L368D / K370S:S267K / S364K / according to EU numbering. E357Q;S364K / E357Q:L368D / K370S;L368D / K370S:S364K;L368E / K370S:S364K;T411E / K360E / Q36 2E:D401K;L368D / K370S:S364K / E357L;K370S:S364K / E357Q;S267K / S364K / E357Q:S267K / L368D / 16. The method of claim 1, comprising a set of amino acid substitutions selected from the group consisting of: K370S; L368D / K370S:S364K / E357Q; S364K:L368D / K370S; S364K:L368E / K370S; D401K:T411E / K360E / Q362E; S364K / E357L:L368D / K370S; and S364K / E357Q:K370S. 23. CD8 in subjects with hematological cancer +1. A method for inducing proliferation of effector memory T cells and NK cells, comprising administering to a subject an effective amount of a heterodimeric protein, the heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to an N-terminus of the first Fc domain; and (ii) a second monomer comprising an IL-15Rα protein and a second Fc domain, wherein the IL-15Rα protein is covalently linked to an N-terminus of the second Fc domain, the first Fc domain and the second Fc domain having the sequence S267K / L368D / K370S:S267K / S364K / E3 according to EU numbering. 57Q;S364K / E357Q:L368D / K370S;L368D / K370S:S364K;L368E / K370S:S364K;T411E / K360E / Q362 E:D401K;L368D / K370S:S364K / E357L;K370S:S364K / E357Q;S267K / S364K / E357Q:S267K / L368D / K 370S; L368D / K370S:S364K / E357Q; S364K:L368D / K370S; S364K:L368E / K370S; D401K:T411E / K360E / Q362E; S364K / E357L:L368D / K370S; and S364K / E357Q:K370S. 24. A method for inducing IFNγ production in a subject suffering from a hematological cancer, comprising administering to the subject an effective amount of a heterodimeric protein, the heterodimeric protein comprising: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain; and (ii) a second monomer comprising an IL-15Rα protein and a second Fc domain, wherein the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain, wherein the first Fc domain and the second Fc domain have the sequence numbers S267K / L368D / K370S:S267K / S364K / K370S according to EU numbering. E357Q;S364K / E357Q:L368D / K370S;L368D / K370S:S364K;L368E / K370S:S364K;T411E / K360E / Q36 2E:D401K;L368D / K370S:S364K / E357L;K370S:S364K / E357Q;S267K / S364K / E357Q:S267K / L368D / 16. The method of claim 1, comprising a set of amino acid substitutions selected from the group consisting of: K370S; L368D / K370S:S364K / E357Q; S364K:L368D / K370S; S364K:L368E / K370S; D401K:T411E / K360E / Q362E; S364K / E357L:L368D / K370S; and S364K / E357Q:K370S. 25. The method of any one of embodiments 20-24, wherein each of the first Fc domain and / or the second Fc domain independently further comprises the amino acid substitutions Q295E, N384D, Q418E and N421D according to EU numbering. 26. The method of any one of embodiments 20-25, wherein each of the first Fc domain and / or the second Fc domain independently further comprises an amino acid substitution selected from the group consisting of: G236R / L328R; E233P / L234V / L235A / G236del / S239K; E233P / L234V / L235A / G236del / S267K; E233P / L234V / L235A / G236del / S239K / A327G; E233P / L234V / L235A / G236del / S267K / A327G; and E233P / L234V / L235A / G236del according to EU numbering, and wherein the Fc domain is derived from an IgG1 or IgG3 Fc domain. 27. The method of any one of embodiments 20-25, wherein each of the first Fc domain and / or the second Fc domain independently further comprises an amino acid substitution selected from the group consisting of: L328R; S239K; and S267K according to EU numbering, and wherein the Fc domain is derived from an IgG2 Fc domain. 28. The method of any one of embodiments 20-25, wherein each of the first Fc domain and / or the second Fc domain independently further comprises an amino acid substitution selected from G236R / L328R; E233P / F234V / L235A / G236del / S239K; E233P / F234V / L235A / G236del / S267K; E233P / F234V / L235A / G236del / S239K / A327G; E233P / F234V / L235A / G236del / S267K / A327G; and E233P / F234V / L235A / G236del according to EU numbering, and wherein the Fc domain is derived from an IgG4 Fc domain. 29. The method of any one of embodiments 20 to 28, wherein the IL-15 protein comprises one or more amino acid substitutions selected from the group consisting of N1D, N4D, D8N, D30N, D61N, E64Q, N65D and Q108E. 30. The method of any one of embodiments 20-28, wherein the IL-15 protein and the IL-15Rα protein each comprise a set of amino acid substitutions or additions selected from E87C:65DPC; E87C:65DCA; V49C:S40C; L52C:S40C; E89C:K34C; Q48C:G38C; E53C:L42C; C42S:A37C and L45C:A37C. 31. The method of any one of embodiments 20 to 30, wherein the IL-15 protein comprises a polypeptide sequence selected from the group consisting of SEQ ID NO:1 and SEQ ID NO:2. 32. The method of any one of embodiments 20 to 31, wherein the IL-15Rα protein comprises a polypeptide sequence selected from the group consisting of SEQ ID NO:3 and SEQ ID NO:4. 33. The method of any one of embodiments 20-24, wherein the first Fc domain comprises the amino acid substitutions L368D and K370S; the second Fc domain further comprises the amino acid substitutions S364K and E357Q; each of the first Fc domain and the second Fc domain further comprises the amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, M428L, and N434S according to EU numbering; the IL-15 protein comprises the amino acid substitutions D30N, E64Q, and N65D; and the IL-15Rα protein comprises SEQ ID NO:4. 34. The method of any one of embodiments 20-24, wherein the first Fc domain comprises amino acid substitutions S364K and E357Q; the second Fc domain comprises amino acid substitutions L368D and K370S; each of the first Fc domain and the second Fc domain further comprises amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, M428L, and N434S according to EU numbering; the IL-15 protein comprises amino acid substitutions D30N, E64Q, and N65D; and the IL-15Rα protein comprises SEQ ID NO:4. 35. The method of any one of embodiments 20-24, wherein the first Fc domain comprises amino acid substitutions L368D and K370S; the second Fc domain comprises amino acid substitutions K246T, S364K, and E357Q; each of the first Fc domain and the second Fc domain further comprises amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, M428L, and N434S according to EU numbering; the IL-15 protein comprises amino acid substitutions D30N, E64Q, and N65D; and the IL-15Rα protein comprises SEQ ID NO:4. 36. The method of any one of embodiments 20-24, wherein the first Fc domain comprises amino acid substitutions S364K and E357Q; the second Fc domain comprises amino acid substitutions K246T, L368D and K370; each of the first Fc domain and the second Fc domain further comprises amino acid substitutions C220S, E233P, L234V, L235A, G236del, S267K, M428L and N434S according to EU numbering; the IL-15 protein comprises amino acid substitutions D30N, E64Q and N65D; and the IL-15Rα protein comprises SEQ ID NO:4. 37. The method of any one of embodiments 20 to 36, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain via a first linker. 38. The method of any one of embodiments 20 to 37, wherein the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain via a second linker. 39. The method of any one of embodiments 20 to 38, wherein the IL-15 protein is covalently linked to the N-terminus of the first Fc domain via a first linker, and the IL-15Rα protein is covalently linked to the N-terminus of the second Fc domain via a second linker. 40. The method of any one of embodiments 37-39, wherein the first linker and / or the second linker are, independently, variable length Gly-Ser linkers. 41. The method of embodiment 40, wherein the first linker and / or the second linker independently comprise a linker selected from the group consisting of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 39), (Ser-Ser-Ser-Ser-Gly)n (SEQ ID NO: 40), (Gly-Ser-Ser-Gly-Gly)n (SEQ ID NO: 41), and (Gly-Gly-Ser-Gly-Gly)n (SEQ ID NO: 42), where n is an integer from 1 to 5. 42. The method of any one of embodiments 20 to 41, wherein the heterodimeric protein is selected from the group consisting of XENP22822, XENP23504, XENP24045, XENP24306, XENP22821, XENP23343, XENP23557, XENP24113, XENP24051, XENP24341, XENP24052, XENP24301, and XENP32803 proteins. 43. The method of any one of embodiments 1 to 5 and 20 to 24, wherein the first monomer comprises the amino acid sequence set forth in SEQ ID NO: 9 and the second monomer comprises the amino acid sequence set forth in SEQ ID NO: 10. 44. The method of any one of embodiments 1-5 and 20-24, wherein the first monomer comprises the amino acid sequence set forth in SEQ ID NO:9 and the second monomer comprises the amino acid sequence set forth in SEQ ID NO:16. 45. The method of any one of embodiments 1-5 and 20-24, wherein the heterodimeric protein is XENP24306, XENP32803, or a combination thereof. 46. ​​The method of any one of embodiments 1-45, wherein a combination of the first heterodimeric protein and the second heterodimeric protein is administered to the subject. 47. The method of embodiment 46, wherein the first heterodimeric protein comprises a first monomer comprising the amino acid sequence set forth in SEQ ID NO:9 and a second monomer comprising the amino acid sequence set forth in SEQ ID NO:10, and the second heterodimeric protein comprises a first monomer comprising the amino acid sequence set forth in SEQ ID NO:9 and a second monomer comprising the amino acid sequence set forth in SEQ ID NO:16. 48. The method of embodiment 46 or 47, wherein the first heterodimeric protein and the second heterodimeric protein are administered simultaneously. 49. The method of embodiment 46 or 47, wherein the first heterodimeric protein and the second heterodimeric protein are administered sequentially. 50. The method of any one of embodiments 1-49, wherein the hematological cancer is selected from the group consisting of leukemia, acute myeloid leukemia, adult acute lymphoblastic leukemia, chronic lymphocytic leukemia, lymphoma, non-Hodgkin's lymphoma, B-cell non-Hodgkin's lymphoma, and multiple myeloma. 51. The method of embodiment 50, wherein the hematological cancer is multiple myeloma. 52. The method of embodiment 51, wherein the multiple myeloma is relapsed or refractory multiple myeloma. 53. The method of embodiment 50, wherein the hematological cancer is B-cell non-Hodgkin's lymphoma. 54. The method of embodiment 50, wherein the hematological cancer is chronic lymphocytic leukemia. 55. The method of any one of embodiments 1-54, wherein the subject has previously been administered one or more treatments. 56. The method of embodiment 55, wherein the previous treatment is an immunomodulatory agent, a proteasome inhibitor, or an anti-CD38 monoclonal antibody. 57. The method of embodiment 56, wherein the immunomodulatory agent is selected from the group consisting of lenalidomide, thalidomide and pomalidomide. 58. The method of embodiment 56, wherein the proteasome inhibitor is selected from the group consisting of bortezomib, carfilzomib and ixazomib. 59. The method of embodiment 56, wherein the anti-CD38 monoclonal antibody is selected from the group consisting of daratumumab, isatuximab, mezagitamab and felzalutamab. 60. The method of any one of embodiments 1-59, wherein the heterodimeric protein or the combination of heterodimeric proteins is administered at a dose selected from the group consisting of about 0.0025 mg / kg, about 0.005 mg / kg, about 0.01 mg / kg, about 0.015 mg / kg, about 0.02 mg / kg, about 0.025 mg / kg, about 0.03 mg / kg, about 0.04 mg / kg, about 0.05 mg / kg, about 0.06 mg / kg, about 0.08 mg / kg, about 0.1 mg / kg, about 0.12 mg / kg, about 0.16 mg / kg, about 0.2 mg / kg, about 0.24 mg / kg and about 0.32 mg / kg body weight. 61. The method of embodiment 60, wherein the heterodimeric protein or the combination of heterodimeric proteins is administered at a dose selected from the group consisting of about 0.01 mg / kg, about 0.02 mg / kg, about 0.04 mg / kg, and about 0.06 mg / kg body weight. 62. The method according to any one of the preceding embodiments, wherein the heterodimeric protein or the combination of heterodimeric proteins is administered at a dose selected from the group consisting of 0.0025 mg / kg, 0.005 mg / kg, 0.01 mg / kg, 0.015 mg / kg, 0.02 mg / kg, 0.025 mg / kg, 0.03 mg / kg, 0.04 mg / kg, 0.05 mg / kg, 0.06 mg / kg, 0.08 mg / kg, 0.10 mg / kg, 0.16 mg / kg, 0.20 mg / kg, 0.24 mg / kg and 0.32 mg / kg body weight. 63. The method of embodiment 62, wherein the heterodimeric protein or combination of heterodimeric proteins is administered at a dose selected from the group consisting of 0.01 mg / kg, 0.02 mg / kg, 0.04 mg / kg, and 0.06 mg / kg body weight. 64. The method of any one of embodiments 1 to 63, further comprising administering an anti-CD38 monoclonal antibody to the subject. 65. The method of embodiment 64, wherein the anti-CD38 monoclonal antibody is selected from the group consisting of daratumumab, isatuximab, mezagitamab and felzalutamab. 66. The method of embodiment 65, wherein the anti-CD38 monoclonal antibody is daratumumab. 67. The method according to any one of embodiments 64 to 66, wherein the heterodimeric protein and the anti-CD38 monoclonal antibody are administered simultaneously. 68. The method according to any one of embodiments 64 to 66, wherein the heterodimeric protein and the anti-CD38 monoclonal antibody are administered sequentially. 69. The method of any one of embodiments 1-68, wherein the heterodimeric protein is administered at a frequency selected from the group consisting of Q1W, Q2W, Q3W, Q4W, Q5W and Q6W. 70. The method of embodiment 69, wherein the heterodimeric protein is administered at a frequency of Q1W for one or more cycles. 71. The method of embodiment 69, wherein the heterodimeric protein is administered at a frequency of Q2W for one or more cycles. 72. The method of embodiment 69, wherein the heterodimeric protein is administered at a frequency of Q4W for one or more cycles. 73. The method of any one of embodiments 64-72, wherein the anti-CD38 monoclonal antibody is administered at a frequency selected from the group consisting of Q1W, Q2W, Q3W, Q4W, Q5W and Q6W. 74. The method of embodiment 73, wherein the anti-CD38 monoclonal antibody is administered at a frequency of Q1W for one or more cycles. 75. The method of embodiment 73, wherein the anti-CD38 monoclonal antibody is administered at a frequency of Q2W for one or more cycles. 76. The method of embodiment 73, wherein the anti-CD38 monoclonal antibody is administered at a frequency of Q4W for one or more cycles. 77. The method of embodiment 73, wherein the heterodimeric protein is administered at a frequency of Q2W and the anti-CD38 monoclonal antibody is administered at a frequency of Q1W for one or more cycles. 78. The method of embodiment 73, wherein the heterodimeric protein is administered at a frequency of Q2W and the anti-CD38 monoclonal antibody is administered at a frequency of Q2W for one or more cycles. 79. The method according to embodiment 73, wherein the heterodimeric protein is administered at a frequency of Q4W and the anti-CD38 monoclonal antibody is administered at a frequency of Q4W for one or more cycles. 80. The method of any one of embodiments 1 to 79, wherein the heterodimeric protein is administered intravenously. 81. The method of any one of embodiments 64-68, wherein the anti-CD38 monoclonal antibody is administered subcutaneously. EXAMPLES

[0226] Example 1: Nonclinical pharmacology studies of XENP24306 As detailed below, the combination of IL15 / IL15Rα heterodimeric proteins (XENP24306 (approximately 82%) and XENP32803 (approximately 18%) ("XENP24306+XENP32803")) was evaluated in multiple in vitro and in vivo studies to characterize preclinical pharmacological properties. In vitro studies demonstrated that the IL15 / IL15Rα heterodimeric protein combination bound to the IL-2 / IL-15βγ receptor complex (CD122 / CD132) in humans and cynomolgus monkeys and inhibited the CD8 receptor in humans and cynomolgus monkeys. + We demonstrated that XENP24306+XENP32803 is active in T cells and NK cells, but inactive in rodent cells (mouse and rat). XENP24306+XENP32803 showed increased neonatal Fc receptor (FcRn) binding (pH 6.0), but had no effector function in terms of mediating antibody-dependent cellular cytotoxicity (ADCC) or complement-dependent cytotoxicity (CDC). Both in vitro and in vivo studies demonstrated that XENP24306+XENP32803 preferentially binds CD8 + Expand T cells and NK cells, CD4 + It has a moderate effect on the expansion of T helper lymphocytes, but a minimal effect on the expansion of Treg populations and cytokine release syndrome (CRS)-associated cytokines.

[0227] In vitro testing The IL-15 components of XENP24306 and XENP32803 contain three amino acid substitutions (D30N, E64Q, and N65D). These substitutions result in reduced potency of IL-15. The binding affinity of XENP24306+XENP32803 to the human and cynomolgus monkey IL-2 / IL-15βγ receptor complex (CD122 / CD132) was determined by surface plasmon resonance. Similar binding kinetics and affinity were observed between the two species, establishing the relevance of cynomolgus monkey as a preclinical animal species for pharmacology and toxicity testing.

[0228] XENP24306 and XENP32803 are effectorless, as indicated by the lack of binding to FcγR and human complement component 1q (C1q), and are not expected to induce target cell killing via ADCC or CDC mechanisms. Specifically, the Fc regions of XENP24306 and XENP32803 were engineered to eliminate binding to human, cynomolgus monkey, and mouse FcγR; no binding interactions were detected by biolayer interferometry (BLI) methods. Additionally, binding of XENP24306+XENP32803 to human C1q, a key component of the C1 complex that initiates the complement system, was assessed using BLI, and no binding was observed.

[0229] Furthermore, the Fc regions of XENP24306 and XENP32803 were engineered to enhance binding to FcRn at lower pH (6.0) with the goal of extending the half-life of XENP24306. Binding interactions with human, cynomolgus monkey, and mouse FcRn were determined by BLI methods, and the affinity of XENP24306+XENP32803 for these receptors was significantly enhanced at pH 6.0, a physiologically relevant pH for endosomal trafficking.

[0230] The selectivity of the XENP24306+XENP32803 species was assessed using a phospho-STAT5 assay. Binding of the IL-15 / IL-15Rα receptor complex to CD122 / CD132-expressing lymphocytes led to activation of Janus kinase signal transducer and activator of transcription signaling pathways, which resulted in phosphorylation of STAT5 and subsequent cell proliferation. XENP24306+XENP32803 inhibited the phospho-STAT5 ... + It did not induce STAT5 phosphorylation in T cells, thereby precluding the use of rodents for toxicity testing or the use of syngeneic mouse models to evaluate XENP24306+XENP32803 for antitumor activity.

[0231] The efficacy of XENP24306+XENP32803 was evaluated in an in vitro cell proliferation assay. + T cells and NK cells showed strong proliferative responses to XENP24306+XENP32803 treatment. Among these two target cell populations, XENP24306+XENP32803 significantly increased NK cells (half maximal effective concentration [EC 50 ]:1.2μg / mL) against CD8 + T cells (EC 50 : 12.7 μg / mL) showed relatively higher efficacy than proliferation (Figures 1A and 1B). + In addition to T cell and NK cell proliferation, XENP24306+XENP32803 also induced IFNγ production in human PBMCs. XENP24306+XENP32803 also induced NK cell (EC 50 : 0.5μg / mL) and CD8 + T cells (EC 50 : 3.8 μg / mL) and validated the cynomolgus monkey as a non-clinical animal species for pharmacology and toxicity studies.

[0232] XENP24306 and XENP32803 are reduced potency recombinant human IL-15 engineered as IL-15 / IL-15Rα heterodimeric Fc fusion proteins. +As shown in terminal effector T cells, XENP24306+XENP32803 showed approximately 900-fold lower potency than recombinant wild-type IL-15 and approximately 400-fold lower potency than a similarly formatted recombinant wild-type IL-15 (rIL15) (wild-type IL-15 / wild-type IL-15Rα heterodimeric Fc fusion; designated XENP22853; SEQ ID NO: 11 (wild-type IL-15-Fc first monomer) and SEQ ID NO: 7 (IL-15Rα-Fc second monomer)) (Figure 2). The potency of XENP24306+XENP32803 was evaluated in various human immune cell subsets. Specifically, human PBMCs were treated with increasing concentrations of XENP24306+XENP32803, recombinant wild-type IL15, or wild-type IL-15 / wild-type IL-15Rα heterodimeric Fc fusion (XENP22853) for 4 days and assayed by flow cytometry for proliferation by intracellular staining of the cell cycle protein Ki67. + CD8 + CD45RA + CCR7 - CD28 - CD95 + CD8 defined by population gating + Results for terminal effector T cells are shown. Curve fitting was generated using the least squares method. EC 50 Values ​​were determined by nonlinear regression analysis using agonist versus response and a variable slope (four parameter) equation. XENP24306+XENP32803 increased the frequency of effector memory CD8+ cells as indicated by increased frequencies of these cell subsets expressing the cell proliferation marker Ki67 and the cell activation markers CD69 and CD25. + and CD4 + XENP24306 enhanced the activation of naive CD8 + or CD4 + There was minimal effect on T cells.

[0233] Two additional in vitro toxicity studies were performed: (1) evaluation of the binding profile of XENP24306+XENP32803 using human plasma membrane protein cell arrays, and (2) evaluation of cytokine release induced by XENP24306+XENP32803, comparing the ability of soluble and immobilized XENP24306+XENP32803 to induce cytokine production. Data from multiple experiments using an optimized concentration of XENP24306+XENP32803 (20 μg / mL) showed that there were no compelling off-target binding interactions identified for XENP24306+XENP32803. The potential risk of cytokine release syndrome (CRS) due to XENP24306+XENP32803 was investigated in vitro using unstimulated human PBMCs. To evaluate the potential of XENP24306+XENP32803 to induce production of cytokines associated with CRS, in vitro stimulation of human PBMCs was performed with the recommended FIH dose (0.01 mg / kg) concentrations of XENP24306+XENP32803 at 10 and 20 μg / mL in blood (43- and 87-fold higher than the expected Cmax (0.23 μg / mL)). Both immobilized and soluble formats of XENP24306+XENP32803 induced IFNγ production. The magnitude of IFNγ induction by XENP24306 (9-14-fold compared to vehicle control) was many fold lower than that observed with anti-CD28 antibody (393-fold compared to vehicle control) or anti-CD3 antibody (1605-fold compared to vehicle control) used as positive controls. No induction of other cytokines, such as IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, or TNF, was observed. XENP24306+XENP32803 did not induce proinflammatory cytokines known to be involved in CRS, such as IL-6 and TNF, indicating that XENP24306+XENP32803 has a low risk of inducing CRS.

[0234] In vivo testing Immune responses were evaluated in cynomolgus monkeys after single or repeated administration of XENP24306+XENP32803. No obvious elevation of inflammatory cytokines such as IL-6, tumor necrosis factor-α (TNFα), and IFNγ was observed after IV administration of XENP24306+XENP32803. Transient elevation of other cytokines and chemokines such as IP-10, MCP-1 (monocyte chemoattractant protein-1), MIP-1α (macrophage inflammatory protein-1α), MIP-1β (macrophage inflammatory protein-1β), TARC (thymus and activation-regulated chemokine), and eotaxin was observed, indicating PD activity. These cytokines and chemokines reached peak serum concentrations within 1 day of administration and returned to pretreatment levels by day 15. Serum concentrations of soluble CD25 peaked approximately 4 days after treatment and returned to pretreatment levels by day 15.

[0235] XENP24306+XENP32803 treatment significantly increased CD8 + The numbers of T cells and NK cells were expanded, validating the expected targeting of immune cell populations. Following an initial reduction in blood lymphocytes, possibly due to margination, CD8 + T and NK cells exhibited a dose-dependent expansion above pretreatment levels. Peak responses in the blood were achieved 1 week after dosing, and cell numbers appeared to return to near pretreatment levels after 2 weeks. CD8 T cells, including central and effector memory, terminal effector, and stem cell memory cells, were identified. + Memory T cell subsets were expanded, whereas naive CD8 + T cells were not expanded. CD4 +T cells, Tregs, B cells, and granulocytes showed minimal expansion or did not respond to XENP24306+XENP32803. A transient and dose-dependent increase in the frequency of Ki67 expression (a marker of cell proliferation) was also observed among these target cell populations, consistent with the expansion of absolute cell numbers. Repeated dosing of XENP24306+XENP32803 (0.03, 0.2, and 0.6 mg / kg, Q2W) showed a transient increase in cytokine and chemokine responses after each dose. Responses to XENP24306+XENP32803 were dose-dependent and reversible at the levels of cytokines, chemokines, and sCD25. Repeated dose toxicity studies showed increased levels of CD8 in peripheral blood. + Expansion of T cells and NK cells (roughly 6-fold at the mid-dose and 14-17-fold at the high-dose) was transient after each dose, with a decline in peak numbers observed after repeated XENP24306+XENP32803 treatments (Figure 3). + T cell and NK cell numbers returned to pretreatment levels after a 4-week recovery period.

[0236] Subjects with multiple myeloma or leukemia can be treated with stem cell transplantation, but complications including graft-versus-host disease (GVHD) can arise if the donor's T cells (graft) attack the subject's healthy cells (host). The ability of XENP24306+XENP32803 to enhance leukocyte proliferation and effector activity was tested in a repeated dose study in a mouse graft-versus-host disease (GVHD) model. XENP24306+XENP32803 (four dose levels: 0.01, 0.03, 0.1, or 0.3 mg / kg administered on days 0, 7, 14, and 21) was evaluated in non-obese diabetic / severe combined immunodeficiency gamma (NSG) mice transplanted with human PBMC as a single agent. The study assessed immune responses against the mouse host, measurable by clinical signs of GVHD (i.e., weight loss and mortality), and immune monitoring assessments, such as peripheral human CD8 +Increases in T cell and NK cell numbers and serum IFNγ concentrations were monitored. Dose-dependent GVHD-inducing activity was observed in mice treated with 0.3 mg / kg XENP24306 + XENP32803, with significant weight loss and CD8 + Significant increases in the numbers of T cells and NK cells and in serum IFNγ concentrations were observed at the lower dose. + A time (days 7, 14, and 21) and dose-dependent increase in the numbers of T cells and NK cells was observed. + T cell expansion was observed only on day 14 at the two highest dose levels tested. The lowest pharmacologically active dose, as evidenced by enhanced NK cell expansion, was 0.01 mg / kg, which significantly increased CD8 + Higher doses were required to demonstrate significant enhancement of T cells and serum IFNγ. Thus, XENP24306+XENP32803 may be a potent inhibitor of CD8 T cells that contribute to GVHD. + It promoted the proliferation and effector enhancement of T cells and NK cells.

[0237] Example 2: Pharmacokinetics and Drug Metabolism in Animals The combination of XENP24306 (approximately 82%) and XENP32803 (approximately 18%) ("XENP24306+XENP32803") bound with equal affinity to the human and cynomolgus monkey IL-2 / IL-15βγ heterodimer receptor complex and inhibited both human and cynomolgus monkey CD8 +It is active in T cells and NK cells. Therefore, the pharmacokinetics (PK) of XENP24306+XENP32803 was investigated in cynomolgus monkeys to support dose selection for Good Laboratory Practice (GLP) toxicity studies, as well as to support dose selection and dosing regimens in First In Human (FIH) studies. An electrochemiluminescence assay was developed and validated to quantify XENP24306+XENP32803 in serum samples from cynomolgus monkeys to support GLP toxicity studies. A goat anti-human IL-15Rα antibody was used as the capture, and mouse anti-human / primate IL-15 biotinylated antibody and sulfo-tagged streptavidin were used as the primary and secondary detection reagents. The lower limit of quantification (LLOQ) was 30.0 ng / mL.

[0238] A time-resolved fluorescence method was developed to quantify the concentrations of XENP24306+XENP32803 in non-GLPPK / PD serum samples from cynomolgus monkeys. The LLOQ of this assay was 1.4 ng / mL.

[0239] Single-dose pharmacokinetics in cynomolgus monkeys An exploratory pilot study design designed to evaluate the validity of the GLP study design and define the maximum tolerated dose was performed. The single-dose pharmacokinetics of XENP24306+XENP32803 were characterized in two independent PK / PD studies in cynomolgus monkeys at 3.0 mg / kg in males and 0.6 mg / kg in females. XENP24306+XENP32803 had a mean clearance (CL) of 66.4 mL / day / kg and a mean volume of distribution at steady state (V ss ) was 107 mL / kg. max and exposure (from time point 0 to infinity [AUC 0-∞ The mean C (area under the concentration-time curve) was 69.6 μg / mL and 45.4 day·μg / mL, respectively. After a single IV dose of 0.6 mg / kg of XENP24306 + XENP32803 to female cynomolgus monkeys, maxwas 11.9 μg / mL, and the exposure (AUC 0-∞ ) was 11.7 days·μg / mL, CL was 52.6 mL / day / kg, and V ss was 89.0 mL / kg. See Table 3. [Table 3]

[0240] Repeated-dose pharmacokinetics in cynomolgus monkeys The toxicokinetics (TK) of XENP24306+XENP32803 was characterized in a 5-week GLP repeated dose toxicity study in cynomolgus monkeys. Three dose levels (0.03, 0.2, and 0.6 mg / kg of XENP24306+XENP32803) were administered 14 days apart for a total of three doses. Systemic exposure was confirmed in all animals, and no gender differences were observed in XENP24306+XENP32803 exposure in cynomolgus monkeys (Figure 4). max was dose-proportional after the first dose. max There was a slight tendency for C to decrease; however, the range (mean ± SD) was 0.01 after the first, second, and third doses. max There was an overlap in AUC 0-14 was slightly below dose proportional after the first dose. In addition, exposure (AUC) was decreased with repeated XENP24306+XENP32803 dosing, especially at the 0.2 mg / kg dose (7.74–5.96 day·μg / mL, 22% decrease) and 0.6 mg / kg dose (21.1–14.9 day·μg / mL, 30% decrease; Table 4). This decrease in systemic exposure (AUC) upon repeated dosing was likely due to increased TMDD as a result of an increase in the target cell population. The CL of XENP24306+XENP32803 after the first dose ranged from 18–28 mL / day / kg, and V ssThe higher than normal IgG clearance observed with XENP24306 + XENP32803 in these studies (<10 mL / day / kg for typical IgG) was likely the result of TMDD. For XENP24306 + XENP32803, the increase in CL with increasing dose after the first dose and the AUC 0-14 Time-varying, nonlinear PK behavior across multiple dose levels was observed, as indicated by the further, less than dose-proportional increase in . Similar PK behavior is expected for XENP24306+XENP32803 in humans. It is likely that the increase in target cell population in response to XENP24306+XENP32803 dosing augments the TMDD effect, resulting in the time-varying pharmacokinetics observed in this study. No accumulation was observed after repeated dosing, as indicated by the decline in AUC values, with AUC ratios between the first and second doses ranging from 0.704 to 0.991-fold (Table 4). [Table 4]

[0241] Example 3: Pharmacodynamic Effects Effects on cytokines, chemokines and soluble CD25 Cytokines were evaluated following single doses of 0.6 or 3.0 mg / kg of IL15 / IL15Rα heterodimer protein in combination with XENP24306 (~82%) and XENP32803 (~18%) in two independent cynomolgus monkey PK / PD studies ("XENP24306+XENP32803"). At both the 0.6 mg / kg and 3.0 mg / kg XENP24306+XENP32803 doses, serum markers, as well as cytokines and chemokines, peaked within 8-16 hours after dosing and largely returned to pretreatment levels by day 15. Serum markers elevated after XENP24306+XENP32803 treatment included eotaxin, eotaxin-3, IL-8, IP-10, MCP-1, MCP-4, MDC, MIP-1α, MIP-1β, and TARC. Increased expression of these cytokines and chemokines may further contribute to lymphocyte proliferation induced by XENP24306+XENP32803.

[0242] Two independent PK / PD studies evaluated sCD25 / IL-2Rα following a single dose of 0.6 or 3.0 mg / kg XENP24306+XENP32803. In both the 0.6 mg / kg and 3.0 mg / kg XENP24306+XENP32803 dose groups, the pattern of sCD25 showed a gradual increase over 3-4 days post-dose, which was consistent with CD25 expression on T cells.

[0243] Effects on lymphocytes Following a single dose of 0.6 mg / kg or 3.0 mg / kg XENP24306+XENP32803, lymphocytes were mildly to moderately decreased by 3 days post-dose. This was followed by a variable dose-dependent moderate to marked increase, peaking 7-9 days post-dose. Lymphocytes then recovered or partially recovered toward pretreatment levels by the end of the study. Monocytes tended to closely mirror lymphocytes, but to a much lesser extent. Blood smears performed on 0.6 mg / kg dose animals showed that many of the lymphocytes were atypical / reactive. mononuclear cell infiltration Minimal to mild mononuclear cell infiltration was observed in the liver sinusoids after a single 0.6 mg / kg dose of XENP24306 + XENP32803. After a single 3.0 mg / kg dose of XENP24306 + XENP32803, mononuclear cell infiltration was observed in the liver, kidneys, lungs, jejunum, bladder, and skin.

[0244] Example 4: Repeat Dose Toxicity Two repeat-dose GLP studies were conducted: (1) a 5-week toxicity study with a 4-week recovery period as described in this Example, and (2) a dedicated cardiovascular safety pharmacology study as described in Example 5.

[0245] A 5-week repeat-dose GLP toxicity study was conducted in male and female cynomolgus monkeys to evaluate the toxicity, pharmacology, and TK of the combination of IL15 / IL15Rα heterodimeric proteins (XENP24306 (approximately 82%) and XENP32803 (approximately 18%)) ("XENP24306+XENP32803"). Animals were administered vehicle (control group) or 0.03, 0.2, or 0.6 mg / kg XENP24306+XENP32803 by IV bolus on days 1, 15, and 29 and necropsied on day 34 (main study cohort) or day 64 (recovery cohort; control and 0.6 mg / kg XENP24306). A 30-day recovery period was designed to assess the reversibility or persistence of effects associated with XENP24306+XENP32803.

[0246] Toxicity assessment was based on clinical observations, body weight, quantitative food testing, ophthalmology, ECG, clinical pathology parameters (hematology, coagulation, clinical chemistry, urinalysis, and urine chemistry), bioanalytical and TK parameters, ADA, cytokines, flow cytometry analysis, significant necropsy findings, organ weights, and histopathological examination.

[0247] TK analysis confirmed systemic exposure of XENP24306+XENP32803 at all dose levels tested. Exposure did not differ by gender. max was dose-proportional after the first dose. AUC0-14 increased with dose, but somewhat less than dose proportionally, and exposure (AUC) decreased upon repeat dosing. XENP24306+XENP32803 appeared to have nonlinear kinetics in cynomolgus monkeys due to TMDD at the dose levels tested (Example 2).

[0248] All findings in the repeated dose GLP toxicity study were consistent with the expected pharmacological response of T cell and NK cell expansion and activation with associated proinflammatory responses. The NOAEL defined from the dedicated repeated dose GLP toxicity study was determined to be 0.03 mg / kg XENP24306+XENP32803. The corresponding safety margins for the proposed FIH dose of XENP24306+XENP32803 of 0.01 mg / kg, IVQ2W, relative to the NOAEL are described in Example 5.

[0249] Example 5: Safety Pharmacology Studies A single, dedicated GLP safety pharmacology study was conducted in telemetry-equipped male cynomolgus monkeys (4 per group, including a vehicle control group) to evaluate the potential effects of the combination of IL15 / IL15Rα heterodimeric protein (XENP24306 (approximately 82%) and XENP32803 (approximately 18%) ("XENP24306+XENP32803")) on the cardiovascular system. XENP24306+XENP32803 was administered by IV bolus injection at 0.03, 0.2, and 0.6 mg / kg (same doses as in the GLP toxicity study) on days 1 and 15, and animals were returned to the colony on day 23. The following parameters and endpoints were evaluated: clinical signs, food intake (quantitative assessment), body weight, cardiovascular assessment (systolic, diastolic, and MAP, heart rate, and ECG (including quantitative assessment and measurements of RR, PR, QRS, and QT intervals and derived rate-corrected QT [QTca] intervals), body temperature, serum albumin concentration, and XENP24306+XENP32803 exposure and ADA incidence.

[0250] XENP24306+XENP32803 was clinically well tolerated at all doses (0.03, 0.2, and 0.6 mg / kg) and all animals survived for the duration of the study without the need for veterinary intervention. No clinical signs, test article-related changes in food intake, weight changes, or ECG abnormalities were observed at any dose. ECGs were qualitatively normal as expected for cynomolgus monkeys, with no treatment-related changes in PR, QRS, or QTca intervals.

[0251] Systemic exposure of XENP24306+XENP32803 was demonstrated at all dose levels. No treatment-related changes in body weight or qualitative food intake occurred during the study.

[0252] Based on the overall findings of the GLP studies in cynomolgus monkeys, the no observed adverse effect level (NOAEL) dose was considered to be 0.03 mg / kg of XENP24306 + XENP32803. Due to the immunoagonistic properties of XENP24306 + XENP32803, determination of the FIH dose was based on the minimal estimated effective level (MABEL) approach. A dose of 0.01 mg / kg of XENP24306 + XENP32803 as single agents, IV, is proposed as the FIH dose of XENP24306 + XENP32803. This FIH dose was chosen based on the EC 20 Based on the results (0.23 μg / mL; geometric mean of 20 donors), the most sensitive in vitro assay for XENP24306+XENP32803 was the in vitro NK cell (CD3 - CD56 + ) proliferation (percentage of cells expressing Ki67). See Figure 1. The recommended FIH dose of 0.01 mg / kg of XENP24306+XENP32803 is presumed to be safe, provides minimal biological effects, and poses minimal risk of treatment-mediated reactions in humans. The C of XENP24306+XENP32803 administered IV to humans at the recommended FIH dose (i.e., 0.01 mg / kg) was max This EC 20The starting dose of 0.01 mg / kg of XENP24306 + XENP32803 in humans has a 3-fold safety margin over the NOAEL dose (0.03 mg / kg of XENP24306 + XENP32803, Q2W) in a 5-week GLP toxicity study in cynomolgus monkeys. The C of XENP24306 + XENP32803 administered IV to humans at 0.01 mg / kg max is the C observed at the NOAEL dose in cynomolgus monkeys. max (0.75±0.04 μg / mL; initial dose). See Table 5. Furthermore, the AUC for XENP24306+XENP32803 at 0.01 mg / kg in humans is predicted to be 1.8-fold lower than the AUC observed at the NOAEL dose in cynomolgus monkeys (Table 5). That is, the C observed at the NOAEL for XENP24306+XENP32803 in the relevant nonclinical GLP toxicity model (cynomolgus monkey) is predicted to be 1.8-fold lower. max and AUC further support the MABEL-based starting dose of XENP24306+XENP32803IV of 0.01 mg / kg, providing an adequate safety margin for the study (Table 5).

[0253] The dosing frequency for XENP24306+XENP32803 in humans is Q2W, which is supported by a 5-week GLP toxicity study in cynomolgus monkeys in which XENP24306+XENP32803 was generally well tolerated with no significant acute toxicity when dosed Q2W. Peak peripheral PD responses (NK and CD8 + Expansion of target cells (e.g., T cells) was achieved 1 week after dosing, and these peripheral target cell numbers declined toward their baseline by the end of the second week after XENP24306+XENP32803 dosing. Furthermore, cytokines and chemokines indicative of PD activity peaked between 8 and 16 hours after dosing and returned to baseline within 14 days of dosing (see Example 3). Thus, an initial dosing frequency of Q2W appears appropriate for a dose-escalation study of monotherapy with XENP24306+XENP32803 during the dose-limiting toxicity observation period that includes the first cycle of study treatment. [Table 5] AUC = area under the concentration time curve; Cmax = maximum observed serum concentration; GLP = good laboratory practice; IV = intravenous; NOAEL = no observed adverse effect level; Q2W = every 2 weeks. a AUC human is the prediction AUC 0-14 (i.e., dose / estimated human clearance), and AUC cyno is the observed AUC after the first dose at the NOAEL (0.03 mg / kg) in a 5-week GLP toxicity study in cynomolgus monkeys 0-14 Estimated human clearance = 11.6 mL / day / kg.

[0254] Example 6: IL15 / IL15Rα and daratumumab combination therapy, an open-label, multicenter, global, dose-escalation study A combination, open-label, multicenter, global dose-escalation study to evaluate the safety, tolerability and pharmacokinetics of IL15 / IL15Rα heterodimeric proteins (XENP24306 (approximately 82%) and XENP32803 (approximately 18%) ("XENP24306+XENP32803")) in combination with the anti-CD38 antibody daratumumab will be conducted in subjects who have received prior treatment (e.g., an immunomodulatory drug (IMiD), proteasome inhibitor, or anti-CD38 monoclonal antibody).

[0255] The study will consist of a screening period of up to 28 days, a treatment period, and a minimum follow-up period of 90 days post-treatment.

[0256] Subjects will be enrolled in two phases: a dose escalation phase and an expansion phase.

[0257] Cohorts of 3 to 9 subjects with hematological cancers (e.g., relapsed or refractory multiple myeloma) will be enrolled in the dose escalation phase of the combination therapy portion of the study. According to a 3+3+3 design (Figure 5), escalating doses of XENP24306+XENP32803 will be administered by IV infusion and 1,800 mg of daratumumab will be administered subcutaneously to determine the maximum tolerated dose (MTD) or maximum administered dose (MAD) of XENP24306+XENP32803 in combination with daratumumab.

[0258] A tentative XENP24306+XENP32803 recommended Phase II dose (RP2D) below the MTD and MAD will be established in the dose escalation phase. After the RP2D is established, additional subjects will be enrolled in the expansion phase and treated at the RP2D. In total, approximately 60 subjects will be enrolled in the study at various global study sites.

[0259] After confirmation of eligibility, subjects will receive XENP24306+XENP32803 in combination with daratumumab. XENP24306+XENP32803 will be administered by IV infusion (starting at 0.01 mg / kg) every 2 weeks (Q2W) for cycles 1-12, then every 4 weeks (Q4W) starting on cycle 13 and thereafter. Daratumumab will be administered subcutaneously (SC) weekly according to the daratumumab SC monotherapy prescribing information (see, e.g., Darzalex SmPC) every week (Q1W) for cycles 1-4, Q2W for cycles 5-12, then Q4W starting on cycle 13. Study treatment cycles last for 2 weeks for cycles 1-12 and 4 weeks for cycles 13 and beyond (Figure 6). Subjects will be evaluated weekly for the first four cycles of combination treatment, and less frequently thereafter, with physical examinations and routine hematological and metabolic laboratory monitoring.

[0260] All adverse events will be reported until 30 days after the last dose of study treatment or until the start of new systemic anticancer therapy, whichever occurs first. Serious adverse events and adverse events of particular interest will continue to be reported until 90 days after the last dose of study treatment or until the start of new systemic anticancer therapy, whichever occurs first. Adverse events will be categorized according to NCI CTCAE v5.0.

[0261] Subjects will undergo disease assessments at screening (baseline) and at regular intervals throughout the study, as measured according to the IMWG Unified Response Criteria. Subjects may continue treatment with XENP24306+XENP32803 and daratumumab until disease progression as determined by the investigator according to the IMWG Unified Response Criteria, unacceptable toxicity, initiation of a new anticancer therapy, or withdrawal from the study.

[0262] Subjects who permanently discontinue XENP24306+XENP32803 and daratumumab will visit for a Discontinuation Visit within 30 days after the last dose of study treatment. A visit where response assessment indicates progressive disease may be used as the Discontinuation Visit.

[0263] Blood samples will be collected at various time points before and after dosing to characterize the safety, tolerability, pharmacokinetics, and activity of XENP24306 + XENP32803 in combination with daratumumab.

[0264] The safety objective of this study is to evaluate the safety tolerability of XENP24306 + XENP32803 in combination with daratumumab based on the following endpoints: Incidence and severity of adverse events with severity determined according to the National Cancer Institute Common Terminology Criteria for Adverse Events, Version 5.0 (NCI CTCAE v5.0); with the exception of cytokine release syndrome (CRS), which will be assessed according to the American Society for Transplantation and Cellular Therapy (ASTCT). Change from baseline in targeted vital signs Changes from baseline in targeted laboratory test results Changes from baseline in ECG parameters

[0265] The pharmacokinetic (PK) objective of this study is to characterize the PK profile of XENP24306 + XENP32803 in combination with daratumumab based on the following endpoints: Serum concentrations of XENP24306+XENP32803 Daratumumab serum concentration

[0266] The activity objective of this study is to provide a preliminary evaluation of the activity of XENP24306 + XENP32803 when administered in combination with daratumumab based on the following endpoints: • Objective response rate (ORR) is defined as the proportion of subjects with a best overall response of stringent complete response (sCR), complete response (CR), very good partial response (VGPR), or partial response (PR) as determined according to the International Myeloma Working Group (IMWG) criteria; • Duration of response (DOR) is defined as the time from the first occurrence of a demonstrated objective response (sCR, CR, VGPR, or PR) to disease progression or death from any cause during the study period, as determined by the investigator according to IMWG criteria (defined as within 30 days after the last dose of study drug); ● Progression-free survival (PFS) is defined as the time from first study treatment to the first occurrence of on-study disease progression or death from any cause (defined as within 30 days after the last dose of study drug), whichever occurs first, as determined by the investigator according to IMWG criteria.

[0267] The immunogenicity objective of this study is to evaluate the immune response to XENP24306 + XENP32803 in combination with daratumumab based on the following endpoints: • Prevalence of XENP24306+XENP32803 anti-drug antibodies (ADA) at baseline and incidence of XENP24306+XENP32803 ADA during the study; • To characterize the immunogenicity of daratumumab when administered in combination with XENP24306+XENP32803 based on the following endpoints: incidence of daratumumab ADA at baseline and incidence of daratumumab ADA during the study; • To evaluate the potential efficacy of ADA based on the following endpoints: relationship between ADA status and safety, PK, or activity endpoints.

[0268] The exploratory biomarker objectives for this study are to identify and / or evaluate biomarkers that predict response to XENP24306 + XENP32803 and daratumumab (i.e., predictive biomarkers), that are early surrogates of activity, that are associated with progression to a more severe disease state (i.e., prognostic biomarkers), that are associated with acquired resistance to XENP24306 + XENP32803 and daratumumab, that are associated with susceptibility to the occurrence of adverse events, or that may result in improved monitoring or surveillance of adverse events (i.e., safety biomarkers), that may provide evidence of XENP24306 + XENP32803 and daratumumab activity (i.e., pharmacodynamic (PD) biomarkers), or that may enhance the knowledge and understanding of disease biology and drug safety, based on the following endpoints: • Relationship of biomarkers in blood and bone marrow to safety, PK, activity, immunogenicity, or other biomarker endpoints.

[0269] Example 7: Combination Therapy, Open-Label, Multicenter, Global, Dose-Escalation Study of XENP24306 in Combination with Daratumumab A combination, open-label, multicenter, global, dose-escalation study to evaluate the safety, tolerability, and pharmacokinetics of XENP24306 in combination with the anti-CD38 antibody daratumumab will be conducted in subjects who have received prior treatment (e.g., immunomodulatory drugs (IMiDs), proteasome inhibitors, or anti-CD38 monoclonal antibodies).

[0270] The study will consist of a screening period of up to 28 days, a treatment period, and a minimum follow-up period of 90 days post-treatment.

[0271] Subjects will be enrolled in two phases: a dose escalation phase and an expansion phase.

[0272] Cohorts of 3 to 9 subjects with hematological cancers (e.g., relapsed or refractory multiple myeloma) will be enrolled in the dose escalation phase of the combination therapy portion of the study. To determine the maximum tolerated dose (MTD) or maximum administered dose (MAD) of XENP24306 in combination with daratumumab, escalating doses of XENP24306 will be administered by IV infusion and 1800 mg of daratumumab will be administered subcutaneously following a 3+3+3 design (Figure 5).

[0273] A tentative XENP24306 recommended Phase II dose (RP2D) below the MTD and MAD will be established in the dose escalation phase. After the RP2D is established, additional subjects will be enrolled in the expansion phase and treated at the RP2D. In total, approximately 60 subjects will be enrolled in the study at various global study sites.

[0274] After confirmation of eligibility, subjects will receive XENP24306 in combination with daratumumab. XENP24306 will be administered by IV infusion (starting at 0.01 mg / kg) every 2 weeks (Q2W) for cycles 1-12, then every 4 weeks (Q4W) starting on cycle 13 and thereafter. Daratumumab will be administered subcutaneously (SC) weekly (Q1W) for cycles 1-4, Q2W for cycles 5-12, then Q4W starting on cycle 13, according to the daratumumab SC monotherapy prescribing information (see, e.g., Darzalex SmPC). Study treatment cycles last for 2 weeks for cycles 1-12 and 4 weeks for cycles 13 and beyond (Figure 6). Subjects will be evaluated weekly for the first 4 cycles of combination treatment, and less frequently thereafter, with physical examination and routine hematological and metabolic laboratory monitoring.

[0275] All adverse events will be reported until 30 days after the last dose of study treatment or until the start of new systemic anticancer therapy, whichever occurs first. Serious adverse events and adverse events of particular interest will continue to be reported until 90 days after the last dose of study treatment or until the start of new systemic anticancer therapy, whichever occurs first. Adverse events will be categorized according to NCI CTCAE v5.0.

[0276] Subjects will undergo disease assessments at screening (baseline) and at regular intervals throughout the study, as measured according to the IMWG Unified Response Criteria. Subjects may continue treatment with XENP24306 and daratumumab until disease progression as determined by the investigator according to the IMWG Unified Response Criteria, unacceptable toxicity, initiation of a new anticancer therapy, or withdrawal from the study.

[0277] Subjects who permanently discontinue XENP24306 and daratumumab will visit the clinic for a Discontinuation Visit within 30 days after the last dose of study treatment. A visit where a response assessment indicates progressive disease may be used as the Discontinuation Visit.

[0278] Blood samples will be collected at various time points before and after dosing to characterize the safety, tolerability, pharmacokinetics, and activity of XENP24306 in combination with daratumumab.

[0279] The safety objective of this study is to evaluate the safety tolerability of XENP24306 in combination with daratumumab based on the following endpoints: Incidence and severity of adverse events with severity determined according to the National Cancer Institute Common Terminology Criteria for Adverse Events, Version 5.0 (NCI CTCAE v5.0); with the exception of cytokine release syndrome (CRS), which will be assessed according to the American Society for Transplantation and Cellular Therapy (ASTCT). Change from baseline in targeted vital signs Changes from baseline in targeted laboratory test results Changes from baseline in ECG parameters

[0280] The pharmacokinetic (PK) objective of this study is to characterize the PK profile of XENP24306 in combination with daratumumab based on the following endpoints: Serum concentration of XENP24306 Serum concentration of daratumumab

[0281] The activity objective of this study is to provide a preliminary evaluation of the activity of XENP24306 when administered in combination with daratumumab based on the following endpoints: • Objective response rate (ORR) is defined as the proportion of subjects with a best overall response of stringent complete response (sCR), complete response (CR), very good partial response (VGPR), or partial response (PR) as determined according to the International Myeloma Working Group (IMWG) criteria; • Duration of response (DOR) is defined as the time from the first occurrence of a demonstrated objective response (sCR, CR, VGPR, or PR) to disease progression or death from any cause during the study period, as determined by the investigator according to IMWG criteria (defined as within 30 days after the last dose of study drug); ● Progression-free survival (PFS) is defined as the time from first study treatment to the first occurrence of on-study disease progression or death from any cause (defined as within 30 days after the last dose of study drug), whichever occurs first, as determined by the investigator according to IMWG criteria.

[0282] The immunogenicity objective of this study is to evaluate the immune response to XENP24306 in combination with daratumumab based on the following endpoints: • Prevalence of XENP24306 anti-drug antibodies (ADA) at baseline and incidence of XENP24306ADA during the study; • To characterize the immunogenicity of daratumumab when administered in combination with XENP24306 based on the following endpoints: the prevalence of daratumumab ADA at baseline and the incidence of daratumumab ADA during the study; • To evaluate the potential efficacy of ADA based on the following endpoints: relationship between ADA status and safety, PK, or activity endpoints.

[0283] The exploratory biomarker objectives for this study are to identify and / or evaluate biomarkers that predict response to XENP24306 and daratumumab (i.e., predictive biomarkers), that are early surrogates of activity, that are associated with progression to a more severe disease state (i.e., prognostic biomarkers), that are associated with acquired resistance to XENP24306 and daratumumab, that are associated with susceptibility to the occurrence of adverse events, or that may result in improved monitoring or surveillance of adverse events (i.e., safety biomarkers), that may provide evidence of XENP24306 and daratumumab activity (i.e., pharmacodynamic (PD) biomarkers), or that may enhance knowledge and understanding of disease biology and drug safety, based on the following endpoints: • Relationship of biomarkers in blood and bone marrow to safety, PK, activity, immunogenicity, or other biomarker endpoints.

[0284] Example 8: Combination Therapy, Open-Label, Multicenter, Global, Dose-Escalation Study of XENP32803 in Combination with Daratumumab A combination, open-label, multicenter, global, dose-escalation study to evaluate the safety, tolerability and pharmacokinetics of XENP32803 in combination with an anti-CD38 antibody, e.g., daratumumab, will be conducted in subjects who have received prior treatment (e.g., an immunomodulatory drug (IMiD), a proteasome inhibitor and an anti-CD38 monoclonal antibody).

[0285] The study will consist of a screening period of up to 28 days, a treatment period, and a minimum follow-up period of 90 days post-treatment.

[0286] Subjects will be enrolled in two phases: a dose escalation phase and an expansion phase.

[0287] Cohorts of 3 to 9 subjects with hematological cancers (e.g., relapsed or refractory multiple myeloma) will be enrolled in the dose escalation phase of the combination therapy portion of the study. To determine the maximum tolerated dose (MTD) or maximum administered dose (MAD) of XENP32803 in combination with daratumumab, escalating doses of XENP32803 will be administered by IV infusion and 1800 mg of daratumumab subcutaneously following a 3+3+3 design (Figure 5).

[0288] A tentative XENP32803 recommended Phase II dose (RP2D) below the MTD and MAD will be established in the dose escalation phase. After the RP2D is established, additional subjects will be enrolled in the expansion phase and treated at the RP2D. In total, approximately 60 subjects will be enrolled in the study at various global study sites.

[0289] After confirmation of eligibility, subjects will receive XENP32803 in combination with daratumumab. XENP32803 will be administered by IV infusion (starting at 0.01 mg / kg) every 2 weeks (Q2W) for cycles 1-12, then every 4 weeks (Q4W) starting on cycle 13 and thereafter. Daratumumab will be administered subcutaneously (SC) weekly (Q1W) for cycles 1-4, Q2W for cycles 5-12, then Q4W starting on cycle 13, according to the daratumumab SC monotherapy prescribing information (see, e.g., Darzalex SmPC). Study treatment cycles last for 2 weeks for cycles 1-12 and 4 weeks for cycles 13 and beyond (Figure 6). Subjects will be evaluated weekly for the first 4 cycles of combination treatment, and less frequently thereafter, with physical examination and routine hematological and metabolic laboratory monitoring.

[0290] All adverse events will be reported until 30 days after the last dose of study treatment or until the start of new systemic anticancer therapy, whichever occurs first. Serious adverse events and adverse events of particular interest will continue to be reported until 90 days after the last dose of study treatment or until the start of new systemic anticancer therapy, whichever occurs first. Adverse events will be categorized according to NCI CTCAE v5.0.

[0291] Subjects will undergo disease assessments at screening (baseline) and at regular intervals during the study, which will be measured according to the IMWG Unified Response Criteria. Subjects may continue treatment with XENP32803 and daratumumab until disease progression as determined by the investigator according to the IMWG Unified Response Criteria, unacceptable toxicity, initiation of a new anticancer therapy, or withdrawal from the study.

[0292] Subjects who permanently discontinue XENP32803 and daratumumab will visit the clinic for a treatment discontinuation visit within 30 days after the last dose of study treatment. A visit where a response assessment indicates progressive disease may be used as the treatment discontinuation visit.

[0293] Blood samples will be collected at various time points before and after dosing to characterize the safety, tolerability, pharmacokinetics, and activity of XENP32803 in combination with daratumumab.

[0294] The safety objective of this study is to evaluate the safety tolerability of XENP32803 in combination with daratumumab based on the following endpoints: Incidence and severity of adverse events with severity determined according to the National Cancer Institute Common Terminology Criteria for Adverse Events, Version 5.0 (NCI CTCAE v5.0); with the exception of cytokine release syndrome (CRS), which will be assessed according to the American Society for Transplantation and Cellular Therapy (ASTCT). Change from baseline in targeted vital signs Changes from baseline in targeted laboratory test results Changes from baseline in ECG parameters

[0295] The pharmacokinetic (PK) objective of this study is to characterize the PK profile of XENP32803 in combination with daratumumab based on the following endpoints: Serum concentration of XENP32803 Daratumumab serum concentration

[0296] The activity objective of this study is to provide a preliminary evaluation of the activity of XENP32803 when administered in combination with daratumumab based on the following endpoints: • Objective response rate (ORR) is defined as the proportion of subjects with a best overall response of stringent complete response (sCR), complete response (CR), very good partial response (VGPR), or partial response (PR) as determined according to the International Myeloma Working Group (IMWG) criteria; • Duration of response (DOR) is defined as the time from the first occurrence of a demonstrated objective response (sCR, CR, VGPR, or PR) to disease progression or death from any cause during the study period, as determined by the investigator according to IMWG criteria (defined as within 30 days after the last dose of study drug); ● Progression-free survival (PFS) is defined as the time from first study treatment to the first occurrence of on-study disease progression or death from any cause (defined as within 30 days after the last dose of study drug), whichever occurs first, as determined by the investigator according to IMWG criteria.

[0297] The immunogenicity objective of this study is to evaluate the immune response to XENP32803 in combination with daratumumab based on the following endpoints: • Prevalence of XENP32803 anti-drug antibodies (ADA) at baseline and incidence of XENP32803 ADA during the study; • To characterize the immunogenicity of daratumumab when administered in combination with XENP32803 based on the following endpoints: the prevalence of daratumumab ADA at baseline and the incidence of daratumumab ADA during the study; • To evaluate the potential efficacy of ADA based on the following endpoints: relationship between ADA status and safety, PK, or activity endpoints.

[0298] The exploratory biomarker objectives for this study are to identify and / or evaluate biomarkers that predict response to XENP32803 and daratumumab (i.e., predictive biomarkers), that are early surrogates of activity, that are associated with progression to a more severe disease state (i.e., prognostic biomarkers), that are associated with acquired resistance to XENP32803 and daratumumab, that are associated with susceptibility to the occurrence of adverse events, or that may result in improved monitoring or surveillance of adverse events (i.e., safety biomarkers), that may provide evidence of XENP32803 and daratumumab activity (i.e., pharmacodynamic (PD) biomarkers), or that may enhance knowledge and understanding of disease biology and drug safety, based on the following endpoints: • Relationship of biomarkers in blood and bone marrow to safety, PK, activity, immunogenicity, or other biomarker endpoints.

Claims

**Claim 1**: A composition comprising a heterodimeric protein for use in: (a) treating blood cancer in a subject in need of treatment for blood cancer; (b) inducing the proliferation of CD8+ effector memory T cells in a subject suffering from blood cancer; (c) inducing the proliferation of NK cells in a subject suffering from blood cancer; (d) inducing the proliferation of CD8+ effector memory T cells and NK cells in a subject suffering from blood cancer; or (e) inducing IFNγ production in a subject suffering from blood cancer; wherein the heterodimeric protein comprises: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently bound to the N-terminus of the first Fc domain; and (ii) a second monomer comprising the sushi domain of an IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently bound to the N-terminus of the second Fc domain; and the IL-15 protein comprises an N65D amino acid substitution and one or more amino acid substitutions selected from the group consisting of N4D, D30N, and E64Q, compared to the amino acid sequence set forth in SEQ ID NO:

1. **Claim 2**: A medicament comprising a heterodimeric protein for: (a) treating blood cancer in a subject in need of treatment for blood cancer; (b) inducing the proliferation of CD8+ effector memory T cells in a subject suffering from blood cancer; (c) inducing the proliferation of NK cells in a subject suffering from blood cancer; (d) inducing the proliferation of CD8+ effector memory T cells and NK cells in a subject suffering from blood cancer; or (e) inducing IFNγ production in a subject suffering from blood cancer; ​ ​ The heterodimeric protein comprises: (i) a first monomer comprising an IL-15 protein and a first Fc domain, wherein the IL-15 protein is covalently bound to the N-terminus of the first Fc domain; and (ii) a second monomer comprising a sushi domain of an IL-15Rα protein and a second Fc domain, wherein the sushi domain of the IL-15Rα protein is covalently bound to the N-terminus of the second Fc domain; and the IL-15 protein comprises an N65D amino acid substitution and one or more amino acid substitutions selected from the group consisting of N4D, D30N, and E64Q, as compared to the amino acid sequence set forth in SEQ ID NO:

1. A medicament.

3. The composition according to claim 1, or the medicament according to claim 2, wherein each of the first Fc domain and the second Fc domain comprises amino acid substitutions E233P, L234V, L235A, G236del, and S267K according to EU numbering.

4. (i) The first Fc domain further comprises amino acid substitutions L368D and K370S according to EU numbering, and the second Fc domain further comprises amino acid substitutions S364K and E357Q according to EU numbering; or (ii) The first Fc domain further comprises amino acid substitutions S364K and E357Q according to EU numbering, and the second Fc domain further comprises amino acid substitutions L368D and K370S according to EU numbering; The composition according to claim 1, or the medicament according to claim 2.

5. (i) The first Fc domain further comprises amino acid substitutions Q295E, N384D, Q418E, and N421D according to EU numbering; (ii) The second Fc domain further comprises amino acid substitutions Q295E, N384D, Q418E, and N421D according to EU numbering; or (iii) The first Fc domain further comprises amino acid substitutions Q295E, N384D, Q418E, and N421D according to EU numbering, and the second Fc domain further comprises amino acid substitutions Q295E, N384D, Q418E, and N421D according to EU numbering; The composition according to claim 1, or the medicament according to claim 2.

6. The composition according to claim 1, or the medicament according to claim 2, wherein the IL-15 protein comprises amino acid substitutions D30N, E64Q, and N65D as compared to the amino acid sequence in SEQ ID NO:

1.

7. The composition according to claim 1, or the medicament according to claim 2, wherein the IL-15 protein comprises the amino acid sequence shown in SEQ ID NO:

5.

8. The composition according to claim 1, or the medicament according to claim 2, wherein the sushi domain of the IL-15Rα protein comprises the amino acid sequence shown in SEQ ID NO:

4.

9. (i) The IL-15 protein is covalently bound to the N-terminus of the first Fc domain via a first linker; (ii) The IL-15Rα protein is covalently bound to the N-terminus of the second Fc domain via a second linker; or (iii) The IL-15 protein is covalently bound to the N-terminus of the first Fc domain via a first linker, and the IL-15Rα protein is covalently bound to the N-terminus of the second Fc domain via a second linker; The composition according to claim 1, or the medicament according to claim 2.

10. The composition or medicament according to claim 9, wherein the first linker and / or the second linker is independently a variable-length Gly-Ser linker selected from the group consisting of (Gly-Gly-Gly-Gly-Ser)n (SEQ ID NO: 39), (Ser-Ser-Ser-Ser-Gly)n (SEQ ID NO: 40), (Gly-Ser-Ser-Gly-Gly)n (SEQ ID NO: 41), and (Gly-Gly-Ser-Gly-Gly)n (SEQ ID NO: 42).

11. The composition according to claim 1, or the medicament according to claim 2, wherein the first monomer comprises the amino acid sequence shown in SEQ ID NO: 9 and the second monomer comprises the amino acid sequence shown in SEQ ID NO:

10.

12. The composition according to claim 1, or the medicament according to claim 2, wherein the blood cancer is selected from the group consisting of leukemia, acute myeloid leukemia, adult acute lymphoblastic leukemia, chronic lymphocytic leukemia, lymphoma, non-Hodgkin lymphoma, B-cell non-Hodgkin lymphoma, and multiple myeloma.

13. The composition according to claim 1, or the medicament according to claim 2, wherein the heterodimeric protein is formulated to be administered at a dosage selected from the group consisting of 0.0025 mg / kg, 0.005 mg / kg, 0.01 mg / kg, 0.015 mg / kg, 0.02 mg / kg, 0.025 mg / kg, 0.03 mg / kg, 0.04 mg / kg, 0.05 mg / kg, 0.06 mg / kg, 0.08 mg / kg, 0.1 mg / kg, 0.12 mg / kg, 0.16 mg / kg, 0.2 mg / kg, 0.24 mg / kg and 0.32 mg / kg body weight.

14. The composition according to claim 1, or the medicament according to claim 2, wherein the heterodimeric protein is formulated to be administered in combination with an anti-CD38 monoclonal antibody.

15. The composition or medicament according to claim 14, wherein the anti-CD38 monoclonal antibody is selected from the group consisting of daratumumab, isatuximab, mezigitamab and ferzalizumab.

16. The composition or medicament according to claim 14, wherein the heterodimeric protein and the anti-CD38 monoclonal antibody are formulated to be administered simultaneously or sequentially.

17. The composition according to claim 1, or the medicament according to claim 2, wherein the heterodimeric protein is formulated to be administered at a frequency selected from the group consisting of Q1W, Q2W, Q3W, Q4W, Q5W and Q6W.

18. The composition or medicament according to claim 14, wherein the anti-CD38 monoclonal antibody is formulated to be administered at a frequency selected from the group consisting of Q1W, Q2W, Q3W, Q4W, Q5W and Q6W.

19. The composition according to claim 1, or the medicament according to claim 2, wherein the heterodimeric protein is formulated to be administered intravenously.

20. The composition or medicament according to claim 14, wherein the anti-CD38 monoclonal antibody is formulated to be administered subcutaneously.

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