LONG-ACTING INTERLEUKIN-15 RECEPTOR AGONIST IN COMBINATION WITH ANOTHER PHARMACOLOGICALLY ACTIVE AGENT

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. §119(e) to U.S.

Provisional Patent Application Serial Nos. 62/758,344, filed November 9, 2018; 62/789,924 filed January 8, 2019; 62/818,003 filed March 13, 2019; 62/825,437 filed March 28, 2019; 62/843,036 filed May 3, 2019; 62/848,372 filed May 15, 2019; and 62/924,015 filed October 21, 2019, the disclosures of which are each incorporated herein by reference.

FIELD

[0002] The instant disclosure is directed to (among other things) therapeutic combinations and compositions comprising a long-acting interleukin- 15 (“IL-15”) receptor agonist and another pharmacologically active agent, i.e., an antibody such as a monoclonal antibody, and related methods of use, for example, in the treatment of conditions responsive to therapy effective to provide, for example, sustained immune activation and anti-tumor activity.

BACKGROUND

[0003] Interleukin- 15 ("IL-15") is a pleiotropic cytokine that was first reported by

Grabstein et al. (Grabstein et al. (1994) Science 264:965-968). Secreted as a l62-amino acid precursor, human IL-15 contains a 29-amino acid leader sequence and a 19-amino acid Pro sequence; the mature protein is therefore 114 amino acids in length. Belonging to the four a-helix bundle family of cytokines, IL-15 binds to a heterotrimeric receptor, wherein a unique a subunit (IL-l5Ra) confers receptor specificity to IL-15, and the b and g subunits of this receptor share commonality with one or more other cytokine receptors. Giri et al. (1995) EMBO J. 14:3654-3663.

[0004] As a cytokine, IL-15 has effects on both the innate immune system and the adaptive immune system (DiSabitino et al. (2011) Cytokine Growth Factor Rev. 22: 19-33). With respect to the innate immune system (which defends the host from foreign invaders generically), IL-15 causes the development of and maintains the survival of natural killer cells ("NK cells") and natural killer-T cells ("NK T cells"), in addition to having other properties. Consistent with their role in the innate immune system, NK cells do not

specifically attack the invading pathogen, rather, these cells destroy compromised host cells (such as tumor cells or virus -infected cells). NK T cells generate immunomodulatory cytokines, particularly interferon-g, which result in a general activation of the immune response.

[0005] With respect to the adaptive immune system (which defends the host from a specific foreign invader following an initial encounter with that particular pathogen), IL-15 is necessary for the maintenance of the immunomodulatory cytokine-generating helper T cells. Importantly, IL-15 also supports the long-term maintenance of“antigen-experienced” memory T cells, which have the ability to rapidly reproduce, thereby generating a faster and stronger immune response upon re-exposure to the particular foreign pathogen invading the host.

[0006] Finally, notwithstanding its specific roles within both the innate and adaptive immune systems, IL-15 has significant and broad effects across both categories of immune systems. In particular, IL-15 inhibits or reduces apoptosis (or cell death) of a number of cells types (including dendritic cells, neutrophils, eosinophils, mast cells, CD4+ T cells, and B cells) associated within both categories of immune systems. IL- 15 -mediated responses have also been shown to have a role in the development, function, and survival of CD8+ T cells and intestinal intraepithelial lymphocytes.

[0007] Because it stimulates the proliferation and maintenance of many cells within the immune system that can fight against cells that appear to the host as foreign (or“non-self’), IL-15 has been proposed for use in the treatments of individuals suffering from cancer (Steel et al. (2012) Trends Pharmacol. Sci. 33(l):35-4l). For example, an IL-l5-based agonist has been proposed to treat myelomas (Wong et al. (2013) Oncolmmunology 2(11), e26442: 1-3). In addition, IL-15 pharmacotherapy has been proposed for treating individuals suffering from viral infections, such as HIV infection.

[0008] A long-acting IL-15 receptor agonist comprising at least one water-soluble polymer (e.g., polyethylene glycol) moiety stably covalently attached to an IL-15 amino group has been described (PCT Application No. PCT/US2018/032817, incorporated by reference herein in its entirety) as providing improved characteristics and in-vivo profiles, such as, for example, potent immune stimulatory effects, low systemic toxicity, stability and/or improved pharmacokinetics, improved therapeutic effects, among other

improvements, in comparison to IL-15 and other IL-15 receptor agonists.

[0009] The generation and use of monoclonal antibodies (mAh) for treating certain cancers, including both hematological malignancies as well as solid tumors, has been

established (Scott et al., 2012, Cancer Immunity, vol. 12, p. 14). The mechanism of action of tumor-associated mAbs includes one or more of the following: direct action on the tumor cell, immune-mediated action, and vascular and stromal ablation. Tumor-associated antigens targeted by mAbs include clusters of differentiation (CD) antigens (e.g., CD20, CD30, CD33, CD52), glycoproteins (e.g., EpCAM, CEA, gpA33, mucins, etc.), glycolipids (e.g., gangliosides such as GD2, GD3 and GM2), vascular targets (e.g., VEGF, VEGFR), growth factors (e.g., ErbBl/EGFR, ErbB2/HER2, ErbB3, c-MET, IGF1R), and stromal and extracellular matrix antigens (e.g., FAP, tenascin). A number of mAbs have been approved by the U.S. FDA for use in oncology (e.g., rituximab, ofatumumab, ZEVALIN®,

BEXXAR®, gemtuzumab ozogamicin, brentuximab vedotin, cetuximab, and panitumumab), although certain types of cancer cells are more vulnerable than others to monoclonal antibody -based therapies.

[0010] Notwithstanding the foregoing approaches, however, there remains a need for improved anticancer immunotherapies. The present disclosure addresses these and other needs by providing, in particular, a combination therapy comprising a long-acting IL-15 receptor agonist and at least one mAh directed against a tumor antigen (the combination having a number of advantageous features to be described in greater detail below), as well as compositions and kits comprising such combinations, as well as related methods of preparation and use, which are believed to be new and completely unsuggested by the art.

SUMMARY

[0011] In a first aspect, a method of treating a subject having cancer is provided herein. In particular, the method comprises administering to a subject a long-acting IL-15 receptor agonist and (b) a monoclonal antibody, such as a monoclonal antibody that targets, i.e., binds to, tumor cells, wherein steps (a) and (b) are carried out concurrently or sequentially and in any order. In some embodiments, the long-acting IL-15 receptor agonist has a structure:

Formula (I) where the structure may also be depicted as [CH30(CH2CH20)n(CH2)mC(0)NH]n -IL-l5, wherein IL-15 is an interleukin- 15 moiety, (n) is an integer from about 150 to about 3,000, (m) is an integer selected from 2, 3, 4, and 5, (n’) is 1, and ~NH~ represents an amino group of the IL-15 moiety; or is a pharmaceutically acceptable salt form thereof. In some particular embodiments, (m) in Formula (I) is 2 or 3. In a preferred embodiment, (m) in Formula (I) is 3. In some particular embodiments, (n) in Formula (I) has an average value of about 227, or an average value of about 340, or an average value of about 454, or an average value of about 681, or an average value of about 909. In one or more embodiments, (n) has a value of about 909.

[0012] In some embodiments, the antibody is an antibody that binds specifically to a tumor antigen selected from a phosphoprotein, a transmembrane protein, a glycoprotein, a gly colipid, and a growth factor.

[0013] In further embodiments of the method, the subject has a solid cancer. In some embodiments, the solid cancer is selected from the group consisting of breast cancer, ovarian cancer, colon cancer, colorectal cancer, gastric cancer, malignant melanoma, multiple myeloma, liver cancer, lymphoma, small cell lung cancer, non-small cell lung cancer, thyroid cancers, kidney cancer, cancer of the bile duct, brain cancer, cervical cancer, maxillary sinus cancer, bladder cancer, esophageal cancer, Hodgkin's disease and adrenocortical cancer, including metastatic forms of any of the foregoing.

[0014] In some other embodiments, the subject has lymphoma or leukemia.

[0015] In some further embodiments, the subject has multiple myeloma.

[0016] In some embodiments of the method, step (a) is carried out prior to step (b).

In other embodiments, step (b) is carried out prior to step (a). In yet further embodiments, step (a) and step (b) are carried out concurrently or substantially concurrently. The method may further comprise one or more additional cycles of dosing of either or both of the long-acting IL-15 receptor agonist and the monoclonal antibody.

[0017] In some embodiments, the administering is effective to stimulate NK

activation and proliferation to an extent greater than observed when the long-acting IL-15 receptor agonist is administered as a single agent, as measured in a suitable animal model. In some additional embodiments, the administering is effective to support CD8 T-cell survival and memory formation to an extent greater than observed when the long-acting IL-15 receptor agonist is administered as a single agent, as measured in a suitable animal model. In some further embodiments, the administering is effective to result in a decrease in the number of tumor cells that is greater than that observed upon administration of the long-acting receptor agonist administered as a single agent (i.e., as a monotherapy) and is greater than that observed upon administration of the monoclonal antibody as a single agent, as measured in a suitable animal model (examples of which are provided herein). In some related embodiments, the administering results in a 3 -fold or greater reduction, or more preferably a 5-fold or greater reduction, or more preferably a 7-fold or greater reduction, in the number of tumor cells in the subject when compared to administration of an equivalent dose of the long-acting receptor agonist as a single agent. In some further embodiments, the administering is effective to induce proliferation of NK cells (i.e., to increase the number of NK cells) and to activate their tumor cell killing capability, e.g., in bone marrow tissue.

[0018] In some embodiments, the long-acting IL-15 receptor agonist is administered subcutaneously. In additional embodiments, the monoclonal antibody is administered intravenously.

[0019] In one or more embodiments, the antibody is a targeted monoclonal antibody that utilizes an antibody-dependent cellular toxicity (ADCC, also referred to as antibody-dependent cell-mediated cytotoxicity) mechanism of action.

[0020] In some embodiments, the monoclonal antibody is selected from an anti-CD 19 antibody, an anti-CD20 antibody, and an anti-CD38 antibody. In further embodiments, the monoclonal antibody that binds specifically to a glycoprotein is selected from an anti-SLAMF7 antibody, an anti-EpCAM antibody, an anti-gpA3 antibody 3, and an anti-FBP antibody. In additional embodiments, the monoclonal antibody that binds specifically to a growth factor is selected from an anti-VEGF antibody, an anti-VEGFR antibody, and an anti-EGFR antibody. In yet some additional embodiments, the antibody is an anti-BCMA antibody. In some additional embodiments, the antibody is a multiple myeloma-targeted antibody.

[0021] In a second aspect, a therapeutic combination for use in treating a condition such as cancer is provided herein. The combination comprises a long-acting IL-15 receptor agonist and a monoclonal antibody, such as a monoclonal antibody that targets, i.e., binds to, tumor cells, including but not limited to the monoclonal antibodies as described herein.

[0022] In some related and more particular embodiments, the long-acting IL-15 receptor agonist has a structure:

Formula (I) wherein IL-15 is an interleukin- 15 moiety, (n) is an integer from about 150 to about 3,000, (m) is an integer selected from 2, 3, 4, and 5, (n’) is 1, and ~NH~ represents an amino group of the IL-15 moiety; or a pharmaceutically acceptable salt form thereof. In yet some additional embodiments, the monoclonal antibody is an antibody that binds specifically to a tumor antigen selected from a phosphoprotein, a transmembrane protein, a glycoprotein, a

gly colipid, and a growth factor. In some embodiments, (m) in Formula (I) is 2 or 3. In some particular embodiments, (m) in Formula (I) is 3. In some further embodiments, (n) in Formula (I) has a value of about 227, or about 340, or about 454, or about 681, or about 909. In one or more embodiments, (n) has a value of about 909.

[0023] In a third aspect, a kit is provided herein. In embodiments, the kit comprises a therapeutic combination of a long-acting IL-15 receptor agonist and a monoclonal antibody as described herein, accompanied by instructions for use, wherein the long-acting IL-15 receptor agonist and the monoclonal antibody are each contained in one or more individual unit dosage forms. The kit and therapeutic combination are useful, for example, for treating a subject with cancer.

[0024] Additional aspects and embodiments are set forth in the following description and claims. The embodiments as described herein are meant to apply equally to each of the aspects described herein and are to be considered both singly and in combination as applicable, unless indicated otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 provides the amino acid sequence of an exemplary recombinant human

IL-15 from A. coli (SEQ ID NO: l), a single, non-glycosylated polypeptide chain containing 115 amino acids, with a molecular weight of 12.9 kDa.

[0026] FIG. 2 is a graph illustrating the percent survival of mice inoculated with

Daudi B lymphoma cells and treated with the following: (i) isotype control, (ii) rituximab at 40 mg/kg, (iii) a long-acting IL-15 receptor agonist at 0.3 mg/kg, or (iv) a combination of rituximab at 40 mg/kg and a long-acting IL-15 receptor agonist at 0.3 mg/kg as described in detail in Example 1.

[0027] FIG. 3 is a graph illustrating NK cell counts in bone marrow tissue following treatment of mice inoculated with Daudi B cells with the following: (i) daratumumab (0.5 mg/kg IP, 14 days following Daudi cell inoculation) and two doses of a long-acting IL-15 receptor agonist, i.e., mono(methoxyPEG-N-butanamide)interleukin-l5 (0.3 mg/kg SC, one dose at each of 14 and 21 days after inoculation), (ii) single agent daratumumab (0.5 mg/kg IP, 14 days following Daudi cell inoculation), (iii) single agent mono(methoxyPEG-N-butanamide)interleukin-l5 (0.3 mg/kg SC, 14 and 21 days after inoculation) when compared to (iv) an untreated control group, as described in Example 2.

[0028] FIG. 4 is a graph illustrating the numbers of Daudi B cells in bone marrow tissue following treatment of mice inoculated with Daudi B cells with the following: (i) daratumumab (0.5 mg/kg IP, 14 days following Daudi cell inoculation) and two doses of mono(methoxyPEG-N-butanamide)interleukin-l5 (0.3 mg/kg SC, one dose at each of 14 and 21 days after inoculation), (ii) single agent daratumumab (0.5 mg/kg IP, 14 days following Daudi cell inoculation), (iii) single agent mono(methoxyPEG-N-butanamide)interleukin-l5 (0.3 mg/kg SC, 14 and 21 days after inoculation) when compared to (iv) an untreated control group, as described in Example 2.

[0029] FIG. 5 is a graph illustrating the percent survival of mice inoculated with

Daudi B cell lymphoma cells, followed by treatment with the following: (i) isotype control, (ii) daratumumab at 0.5 mg/kg IP (iii) a long-acting IL-15 receptor agonist,

mono(methoxyPEG-N-butanamide)interleukin-l5, at 0.3 mg/kg SC, or (iv) a combination of the long-acting IL-15 receptor agonist at 0.3 mg/kg and daratumumab at 0.5 mg/kg, SC as described in detail in Example 3.

[0030] FIG. 6 is a graph illustrating granzyme B induction in bone marrow NK cells following treatment of mice inoculated with Daudi B cells with: (i) daratumumab (0.5 mg/kg IP, 14 days following Daudi cell inoculation) and two doses of mono(methoxyPEG-N-butanamide)interleukin-l5 (0.3 mg/kg SC, one dose at each of 14 and 21 days after inoculation, (ii) single agent daratumumab (0.5 mg/kg IP, 14 days following Daudi cell inoculation), (iii) single agent mono(methoxyPEG-N-butanamide)interleukin-l5 (0.3 mg/kg SC, 14 and 21 days after inoculation), when compared to (iv) an untreated control group, as described in detail in Example 2.

[0031] FIGs. 7A and 7B are graphs illustrating the fraction of NK cells in the bone marrow compartment expressing NKG2A (FIG. 7A) or NKG2D (FIG. 7B) on the cell surface following treatment of mice inoculated with Daudi B cells with: (i) daratumumab (0.5 mg/kg IP, 14 days following Daudi cell inoculation) and two doses of Conjugate 1 (0.3 mg/kg or 0.03 mg/kg SC, one dose at each of 14 and 21 days after inoculation, (ii) single agent daratumumab (0.5 mg/kg IP, 14 days following Daudi cell inoculation), (iii) single agent Compound 1 (0.3 mg/kg SC, 14 and 21 days after inoculation), when compared to (iv) an untreated control group or (v) an isotype control (0.5 mg/kg), as described in detail in Example 4.

[0032] FIGs. 8A-8D are histograms illustrating %proliferation of human NK cells within a human peripheral blood mononuclear cell (PBMC) preparation with (i) Compound 1 alone (FIG. 8C), (ii) hlgG alone (FIG. 8B), (iii) Compound 1 + hlgG (FIG. 8D), or (iv) an untreated control (FIG. 8 A), as described in detail in Example 5.

[0033] FIG. 9A is a graph illustrating the median fluorescence intensity (MFI) signal for CD69 detecting antibodies on the surface of CD56+ NK cells within a PBMC preparation cultured overnight with (i) a hlgG coated plate, (ii) Compound 1 (1 pg/ml), (iii) a hlgG coated plate + Compound 1 (1 pg/ml), or (ii) a control showing NK cell activation, as described in detail in Example 6.

[0034] FIG. 9B is a graph illustrating the median fluorescence intensity (MFI) signal for CDl07a detecting antibodies on the surface of CD56+ NK cells within a PBMC preparation cultured overnight with (i) a hlgG coated plate, (ii) Compound 1 (1 pg/ml), (iii) a hlgG coated plate + Compound 1 (1 pg/ml), or (ii) a control showing NK cell activation, as described in detail in Example 6.

[0035] FIG. 9C is a graph illustrating granzyme B induction in human PBMCs following exposure to: (i) a hlgG coated plate, (ii) Compound 1 (1 pg/ml), a hlgG coated plate + Compound 1 (1 pg/ml), or (ii) a control, as described in detail in Example 6. The graph illustrates the secreted Granzyme B concentration in pg/ml for each of the four treatments.

[0036] FIG. 10A is a graph illustrating the pSTAT5 percent positivity within KHYG- 1 cells after incubation with IL-15 or a long-acting IL-15 receptor agonist

(mono(methoxyPEG-N-butanamide)interleukin-l5), as described in detail in Example 7.

FIG. 10B is a graph of % maximal proliferation of KHYG-l cells after incubation with IL-15 or a long-acting IL-15 receptor agonist (mono(methoxyPEG-N-butanamide)interleukin-l5), as described in detail in Example 7.

[0037] FIG. 11 is a graph illustrating the % maximal proliferation of CD56+ human

NK cells after incubation with IL-15 or a long-acting IL-15 receptor Agonist

(mono(methoxyPEG-N-butanamide)interleukin-l5), as described in detail in Example 8.

[0038] FIG. 12 is a graph illustrating the %7-AAD+ target cells for human multiple myeloma cells pre-coated with daratumumab (+) after stimulation with a long-acting IL-15 receptor agonist (mono(methoxyPEG-N-butanamide)interleukin-l5) (+) or untreated (-), as described in detail in Example 9.

[0039] FIG. 13A is a graph illustrating the fraction of NK cells in the bone marrow compartment expressing CD 16 (FIG. 13 A) on the cell surface (% of cells expressing CD 16 in the total NK cells) following treatment of mice inoculated with Daudi B cells with: (i) daratumumab (0.5 mg/kg IP, 14 days following Daudi cell inoculation) and two doses of Conjugate 1 (0.3 mg/kg or 0.03 mg/kg SC, one dose at each of 14 and 21 days after inoculation, (ii) single agent daratumumab (0.5 mg/kg IP, 14 days following Daudi cell

inoculation), (iii) single agent Compound 1 (0.3 mg/kg SC, 14 and 21 days after inoculation), when compared to (iv) an untreated control group or (v) an isotype control (0.5 mg/kg) , as described in detail in Example 10.

[0040] FIG. 13B is a graph illustrating the CD 16 expression change (increase in

Compound 1 treated groups) on a per cell basis for CD 16+ bone marrow NK cells as measured by median fluorescence intensity (MFI) signal following treatment of mice inoculated with Daudi B cells with: (i) daratumumab (0.5 mg/kg IP, 14 days following Daudi cell inoculation) and two doses of Conjugate 1 (0.3 mg/kg or 0.03 mg/kg SC, one dose at each of 14 and 21 days after inoculation, (ii) single agent daratumumab (0.5 mg/kg IP, 14 days following Daudi cell inoculation), (iii) single agent Compound 1 (0.3 mg/kg SC, 14 and 21 days after inoculation), when compared to (iv) an untreated control group or (v) an isotype control (0.5 mg/kg) , as described in detail in Example 10.

[0041] FIG. 14 is a graph illustrating the granzyme B expression in individual bone marrow NK cells as measured by median fluorescence intensity (MFI) signal following treatment of mice inoculated with Daudi B cells with: (i) daratumumab (0.5 mg/kg IP, 14 days following Daudi cell inoculation) and two doses of Compound 1 (0.3 mg/kg or 0.03 mg/kg SC, one dose at each of 14 and 21 days after inoculation, (ii) single agent

daratumumab (0.5 mg/kg IP, 14 days following Daudi cell inoculation), (iii) single agent Compound 1 (0.3 mg/kg SC, 14 and 21 days after inoculation), when compared to (iv) an untreated control group or (v) an isotype control (0.5 mg/kg) , as described in detail in Example 11.

[0042] FIGs. 15A and 15B are graphs illustrating %7-AAD+ target cells for human multiple myeloma cells pre-coated with daratumumab (+) (FIG. 15 A) or rituximab (+) (FIG. 15B) after stimulation with a long-acting IL-15 receptor agonist (mono(methoxyPEG-N-butanamide)interleukin-l5) (+) or untreated (-), as described in detail in Example 12.

[0043] FIG. 16 is a graph illustrating the percent survival of SCID or SCID beige mice inoculated with Daudi B cell lymphoma cells, followed by treatment with the following: (i) untreated control for SCID (□), (ii) untreated control for SCID beige (o) mice, (iii) a combination of the long-acting IL-15 receptor agonist at 0.3 mg/kg and daratumumab at 0.5 mg/kg, SC for SCID mice (■); and (iv) a combination of the long-acting IL-15 receptor agonist at 0.3 mg/kg and daratumumab at 0.5 mg/kg, SC for SCID beige mice (·) as described in detail in Example 13.

[0044] FIG. 17A is a graph illustrating Daudi cell counts in bone marrow tissue following treatment of mice inoculated with Daudi B cells with the following: (i) high dose daratumumab (5 mg/kg IP, 14 days following Daudi cell inoculation) and two low doses of a long-acting IL-15 receptor agonist, i.e., mono(methoxyPEG-N-butanamide)interleukin-l5 (compound 1) (0.03 mg/kg IV, one dose at each of 14 and 21 days after inoculation) (¨), (ii) single agent high dose daratumumab (5 mg/kg IP, 14 days following Daudi cell inoculation) (▼), (iii) single agent low dose mono(methoxyPEG-N-butanamide)interleukin-l5

(compound 1) (0.03 mg/kg IV, 14 and 21 days after inoculation) (A) when compared to (iv) an untreated control group (·), as described in detail in Example 14. FIG. 17B is a graph illustrating Daudi cell counts in bone marrow tissue following treatment of mice inoculated with Daudi B cells with the following: (i) low dose daratumumab (0.05 mg/kg IP, 14 days following Daudi cell inoculation) and two high doses of a long-acting IL-15 receptor agonist, i.e., mono(methoxyPEG-N-butanamide)interleukin-l5 (compound 1) (0.6 mg/kg IV, one dose at each of 14 and 21 days after inoculation) (¨), (ii) single agent low dose daratumumab (0.05 mg/kg IP, 14 days following Daudi cell inoculation) (▼), (iii) single agent high dose mono(methoxyPEG-N-butanamide)interleukin-l5 (compound 1) (0.6 mg/kg IV, 14 and 21 days after inoculation) (A) when compared to (iv) an untreated control group (·), as described in detail in Example 14.

[0045] FIG. 18A is a graph illustrating the intratumoral fraction of NK cells at day 3 or day 5 following treatment of mice bearing subcutaneous HCT-116 colon colorectal cell tumors with cetuximab (20 mg/kg, IP) and Conjugate 1 (0.3 mg/kg IV) in comparison to a vehicle control, as described in detail in Example 15.

[0046] FIG. 18B is a graph illustrating intratumoral NK cell counts at day 3 or day 5 following treatment of mice bearing subcutaneous HCT-l 16 tumors with cetuximab (20 mg/kg, IP) and Conjugate 1 (0.3 mg/kg IV) in comparison to a vehicle control, as described in detail in Example 15.

[0047] FIG. 18C is a graph illustrating NK cell proliferation as shown by %Ki67 positivity in blood or tumor cells following treatment of mice bearing subcutaneous HCT-l 16 tumors with cetuximab (20 mg/kg, IP) and Conjugate 1 (0.3 mg/kg IV) in comparison to a vehicle control, as described in detail in Example 15.

[0048] FIG. 18D is a graph illustrating Granzyme B expression (%GzmB+) in blood or tumor cells following treatment of mice bearing subcutaneous HCT-l 16 tumors with cetuximab (20 mg/kg, IP) and Conjugate 1 (0.3 mg/kg IV) in comparison to a vehicle control, as described in detail in Example 15.

[0049] FIG. 18E is a graph illustrating the CD 16 cell surface expression on NK cells as measured by median fluorescence intensity (MFI) signal following treatment of mice bearing subcutaneous HCT-116 tumors with cetuximab (20 mg/kg, IP) and Conjugate 1 (0.3 mg/kg IV) in comparison to a vehicle control, as described in detail in Example 15.

[0050] FIG. 18F is a graph illustrating the intratumoral fraction of NK cells expressing NKG2D (%NKG2D+) on the cell surface following treatment of mice bearing subcutaneous HCT-l 16 tumors with cetuximab (20 mg/kg, IP) and Conjugate 1 (0.3 mg/kg IV) in comparison to a vehicle control, as described in detail in Example 15.

[0051] FIG. 19A is a graph illustrating the intratumoral fraction of NK cells at day 3 or day 5 following treatment of mice bearing subcutaneous FaDu squamous cell carcinoma tumors with cetuximab (20 mg/kg, IP) and Conjugate 1 (0.3 mg/kg IV) in comparison to a vehicle control, as described in detail in Example 16.

[0052] FIG. 19B is a graph illustrating intratumoral NK cell counts at day 3 or day 5 following treatment of mice bearing subcutaneous FaDu tumors with cetuximab (20 mg/kg, IP) and Conjugate 1 (0.3 mg/kg IV) in comparison to a vehicle control, as described in detail in Example 16.

[0053] FIG. 19C is a graph illustrating NK cell proliferation as shown by %Ki67 positivity in blood or tumor cells following treatment of mice bearing subcutaneous FaDu tumors with cetuximab (20 mg/kg, IP) and Conjugate 1 (0.3 mg/kg IV) in comparison to a vehicle control, as described in detail in Example 16.

[0054] FIG. 19D is a graph illustrating Granzyme B expression (%GzmB+) in blood or tumor cells following treatment of mice bearing subcutaneous FaDu tumors with cetuximab (20 mg/kg, IP) and Conjugate 1 (0.3 mg/kg IV) in comparison to a vehicle control, as described in detail in Example 16.

[0055] FIG. 19E is a graph illustrating the CD 16 cell surface expression on NK cells as measured by median fluorescence intensity (MFI) signal following treatment of mice bearing subcutaneous FaDu tumors with cetuximab (20 mg/kg, IP) and Conjugate 1 (0.3 mg/kg IV) in comparison to a vehicle control, as described in detail in Example 16.

[0056] FIG. 19F is a graph illustrating the intratumoral fraction of NK cells expressing NKG2D (%NKG2D+) on the cell surface following treatment of mice bearing subcutaneous FaDu tumors with cetuximab (20 mg/kg, IP) and Conjugate 1 (0.3 mg/kg IV) in comparison to a vehicle control, as described in detail in Example 16.

[0057] FIG. 20 is a graph illustrating the relative tumor volume for 0-27 days following treatment of mice inoculated with H1975 lung carcinoma cells with the following: (i) cetuximab (0.25 mg/kg, IP) administered on day 9, 12, and 16 after tumor inoculation and Compound 1(0.3 mg/kg, IV) administered on day 9, 16 and 23 days after inoculation (D), (ii) single agent cetuximab (0.25 mg/kg, IP, BIWx3) (A), (iii) single agent Compound 1 (0.3 mg/kg, IV, q7dx3) (▼), in comparison to a vehicle control (·), as described in detail in Example 17.

[0058] FIG. 21A is a graph illustrating the relative tumor volume for 0-21 days following treatment of mice inoculated with HT-29 colorectal carcinoma cells with the following: (i) cetuximab (40 mg/kg, IP, BIWx3) and Compound 1(0.3 mg/kg, IV, q7dx3)

(D), (ii) single agent cetuximab (40 mg/kg, IP, BIWx3) (A), (iii) single agent Compound 1 (0.3 mg/kg, IV, q7dx3) (▼), in comparison to a vehicle control (·), as described in detail in Example 18.

[0059] FIG. 21B is a graph illustrating the tumor growth delay (TVQT) as percent survival of mice inoculated with HT-29 colorectal carcinoma cells and treated with the following: (i) cetuximab (40 mg/kg, IP, BIWx3) and Compound 1(0.3 mg/kg, IV, q7dx3)

(▼), (ii) single agent cetuximab (40 mg/kg, IP, BIWx3) (■), (iii) single agent Compound 1 (0.3 mg/kg, IV, q7dx3) (A), in comparison to a vehicle control (·) for 0-23 days after treatment start (mean tumor volume of -150 mm3), as described in detail in Example 18.

[0060] FIG. 22A is a graph illustrating the relative tumor volume for 0-19 days following treatment of mice inoculated with HCT-l 16 colorectal carcinoma cells with the following: (i) cetuximab (40 mg/kg, IP, BIWx3) and Compound 1(0.3 mg/kg, IV, q7dx3)

(D), (ii) single agent cetuximab (40 mg/kg, IP, BIWx3) (A), (iii) single agent Compound 1 (0.3 mg/kg, IV, q7dx3) (▼), in comparison to a PBS vehicle control (OP, BIWx3) (·), as described in detail in Example 19.

[0061] FIG. 22B is a graph illustrating the tumor growth delay (TVQT) as percent survival of mice inoculated with HCT-l 16 colorectal carcinoma cells and treated with the following: (i) cetuximab (40 mg/kg, IP, BIWx3) and Compound 1(0.3 mg/kg, IV, q7dx3)

(D), (ii) single agent cetuximab (40 mg/kg, IP, BIWx3) (A), (iii) single agent Compound 1 (0.3 mg/kg, IV, q7dx3) (▼), in comparison to a PBS vehicle control (IP, BIWx3) (·), as described in detail in Example 19.

[0062] FIG. 23A is a graph illustrating the %CD45-EpCAM+7-AAD+ target cells for

HCT-l 16 colorectal carcinoma cells pre-coated with cetuximab (+) alone or after stimulation with Compound 1 (+), with an isotype control (+), or untreated (-), as described in detail in Example 20.

[0063] FIG. 23B is a graph illustrating the %CD45- 7-AAD+ target cells for FaDu squamous cell carcinoma cells (HNSCC) pre-coated with cetuximab (+) alone or after stimulation with Compound 1 (+), with an isotype control (+), or untreated (-), as described in detail in Example 20.

[0064] FIG. 24 is a graph illustrating the relative tumor volume for 0-35 days following treatment of mice inoculated with SKOV-3 ovarian adenocarcinoma cells with the following: (i) trastuzumab (13.5 mg/kg, IV, BIWx3) and Compound 1 (0.3 mg/kg, IV, q7dx3) (D), (ii) single agent trastuzumab (13.5 mg/kg, IV, BIWx3) (A), (iii) single agent Compound 1 (0.3 mg/kg, IV, q7dx3) (▼), in comparison to a vehicle control (·), as described in detail in Example 21.

[0065] FIG. 25 is a graph illustrating the relative tumor volume for 0-35 days following treatment of mice inoculated with NCI-N87 gastric carcinoma cells with the following: (i) trastuzumab (3/1/1 mg/kg, IV, q7dx3) and Compound 1 (0.3 mg/kg, IV, q7dx3) (D), (ii) single agent trastuzumab (3/1/1 mg/kg, IV, q7dx3) (A), (iii) single agent Compound 1 (0.3 mg/kg, IV, q7dx3) (▼), in comparison to a vehicle control (·), as described in detail in Example 22.

DETAILED DESCRIPTION

[0066] Before describing one or more aspects or embodiments of the present disclosure in detail, it should be noted that the presented disclosure is not intended to be limited to the particular synthetic techniques, IL-15 moieties, and the like, as such may vary as would be understood by one having ordinary skill in the art to which this disclosure applies.

[0067] In describing and claiming certain features of this disclosure, the following terminology will be used in accordance with the definitions described below unless indicated otherwise.

[0068] As used in this specification, the singular forms“a,”“an,” and“the” include plural referents unless the context clearly dictates otherwise.

[0069] “Water soluble, non peptidic polymer” refers to a polymer that is at least 35%

(by weight) soluble, preferably greater than 70% (by weight), and more preferably greater than 95% (by weight) soluble, in water at room temperature. Typically, an unfiltered aqueous preparation of a "water soluble" polymer transmits at least 75%, more preferably at least 95%, of the amount of light transmitted by the same solution after filtering. It is most preferred, however, that the water-soluble polymer is at least 95% (by weight) soluble in water or completely soluble in water. With respect to being“non-peptidic,” a polymer is non-peptidic when it has less than 35% (by weight) of amino acid residues.

[0070] “PEG” or“polyethylene glycol,” as used herein, is meant to encompass any water-soluble poly(ethylene oxide). Unless otherwise indicated, a“PEG polymer” or a polyethylene glycol is one in which substantially all (preferably all) monomeric subunits are ethylene oxide subunits, though, the polymer may contain distinct end capping moieties or functional groups, e.g., for conjugation. PEG polymers for use in the present disclosure will comprise one of the two following structures: “-(CH2CH20)n-” or“-(CH2CH20)n-iCH2CH2-,” depending upon whether or not the terminal oxygen(s) has been displaced, e.g., during a synthetic transformation. As stated above, for PEG polymers, the variable (n) may range from about 3 to 4000, and the terminal groups and architecture of the overall PEG can vary. Exemplary or preferred PEG-comprising molecules may however comprise one or more particular PEG architectures and/or linkers, and/or molecular weight ranges.

[0071] Molecular weight in the context of a water-soluble polymer, such as PEG, can be expressed as either a number average molecular weight or a weight average molecular weight. Unless otherwise indicated, all references to molecular weight herein refer to the weight average molecular weight. Both molecular weight determinations, number average and weight average, can be measured using gel permeation chromatography or other liquid chromatography techniques (e.g. gel filtration chromatography). Most commonly employed are gel permeation chromatography and gel filtration chromatography. Other methods for determining molecular weight include end-group analysis or the measurement of colligative properties (e.g., freezing-point depression, boiling-point elevation, or osmotic pressure) to determine number average molecular weight or the use of light scattering techniques, ultracentrifugation, MALDI TOF, or viscometry to determine weight average molecular weight. PEG polymers are typically poly disperse (i.e., the number average molecular weight and the weight average molecular weight of the polymers are not equal), possessing low polydispersity values of preferably less than about 1.2, more preferably less than about 1.15, still more preferably less than about 1.10, yet still more preferably less than about 1.05, and most preferably less than about 1.03.

[0072] A“physiologically cleavable” or“hydrolyzable” or“degradable” bond is a relatively labile bond that reacts with water (i.e., is hydrolyzed) under physiological conditions. The tendency of a bond to hydrolyze in water may depend not only on the general type of linkage connecting two atoms within a given molecule but also on the substituents attached to these atoms. Appropriate hydrolytically unstable or weak linkages may include but are not limited to carboxylate ester, phosphate ester, anhydrides, acetals, ketals, acyloxyalkyl ether, imines, orthoesters, peptides, oligonucleotides, thioesters, and carbonates.

[0073] A covalent“releasable” linkage, for example, in the context of a polyethylene glycol that may be covalently attached to an active moiety such as interleukin- 15, is one that releases or detaches a polyethylene glycol polymer from the active moiety under physiological conditions, e.g., by any suitable mechanism, at a rate that is clinically useful and includes, for example and without limitation, hydrolyzable bonds and enzymatically degradable linkages.

[0074] An“enzymatically degradable linkage” means a linkage that is subject to degradation by one or more enzymes.

[0075] A“stable” linkage or bond refers to a chemical bond that is substantially stable in water, that is to say, does not undergo hydrolysis under physiological conditions to any appreciable extent over an extended period of time. Examples of hydrolytically stable linkages generally include but are not limited to the following: carbon-carbon bonds (e.g., in aliphatic chains), ethers, amides, amines, and the like. Generally, a stable linkage is one that exhibits a rate of hydrolysis of less than about 1-2% per day under physiological conditions. Hydrolysis rates of representative chemical bonds can be found in most standard chemistry textbooks.

[0076] “Substantially” or“essentially” means nearly totally or completely, for instance, 95% or greater of a given quantity.

[0077] Similarly,“about” or“approximately” as used herein means within plus or minus 5% of a given quantity.

[0078] “Optional” or“optionally” means that the subsequently described circumstance may but need not necessarily occur, so that the description includes instances where the circumstance occurs and instances where it does not.

[0079] “Pharmaceutically acceptable excipient” or“pharmaceutically acceptable carrier” refers to a component that may be included in a composition as described herein and causes no significant adverse toxicological effects to a subject.

[0080] The phrases“pharmaceutically effective amount” and“pharmacologically effective amount” and“therapeutically effective amount” and“physiologically effective amount” are used interchangeably herein and refer to the amount of a long-acting IL-15 receptor agonist as provided herein or the amount of a monoclonal antibody as described herein that is needed to provide a desired level of the substance in the bloodstream or in a target tissue to produce a desired biological or medicinal response. For example, such a response may be to destroy target cancer cells and/or to slow or arrest the progression of cancer in a subject, and/or to increase the number of NK cells of a patient. The term also applies to a dose that will induce a particular response in target cells. The precise amount will depend upon numerous factors, such as for example, the particular condition being treated, the intended patient population, individual patient considerations, the components and physical characteristics of the therapeutic composition and particular combination to be administered, and the like, and may be readily determined by one skilled in the art.

[0081] The term“IL-15 moiety,” as used herein, refers to a peptide or protein moiety having human IL-15 activity. In addition, the term“IL-15 moiety” encompasses both the IL-15 moiety prior to conjugation as well as the IL-15 moiety residue following conjugation. As will be explained in further detail below, one of ordinary skill in the art can determine whether any given moiety has IL-15 activity. Proteins comprising an amino acid sequence corresponding to any one of SEQ ID NOs: 1 through 3 is an IL-15 moiety, as well as any protein or polypeptide substantially homologous thereto. As used herein, the term“IL-15 moiety” includes such peptides and proteins modified deliberately, as for example, by site directed mutagenesis or accidentally through mutations. These terms also include analogs having from 1 to 6 additional glycosylation sites, analogs having at least one additional amino acid at the carboxy terminal end of the peptide or protein wherein the additional amino acid(s) includes at least one glycosylation site, and analogs having an amino acid sequence which includes at least one glycosylation site. The term includes naturally, recombinantly and synthetically produced IL-15 moieties. The IL-15 moiety may be produced by any suitable method as known in the art. In embodiments, the IL-15 moiety is recombinantly produced in an E. coli or a Chinese hamster ovary (CHO) expression system. Reference to a long-acting IL-15 receptor agonist as described herein is meant to encompass

pharmaceutically acceptable salt forms thereof.

[0082] An“antibody” as used herein, is meant in a broad sense and includes glycoproteins belonging to the immunoglobulin (Ig) superfamily. Antibodies are intended to include polyclonal antibodies, monoclonal antibodies (e.g. murine, human, human-adapted, humanized and chimeric), antibody fragments, and single chain antibodies that bind specifically to an antigen (e.g. a tumor antigen). The fragment, antigen-binding (Fab) region comprises a constant domain and at least one variable domain from each of the heavy and light chains. The antibodies as described herein at least have antibody dependent cellular cytotoxicity (ADCC) as a mechanism of action.

[0083] The term“monoclonal antibody” (mAh) as used herein refers to non-naturally occurring antibody molecules obtained from a population of substantially homogeneous molecules such that the antibody molecules have primary sequences are essentially identical, excepting naturally occurring mutations that may be present in minor amounts. Monoclonal antibodies are highly specific to a single binding site or a particular epitope. A monoclonal antibody is an example of an isolated antibody. Monoclonal antibodies may be produced by any means as known in the art including, without limitation, hybridoma culture techniques, recombinant methods, and transgenic methods.

[0084] It should be understood the target binding sequence of the antibody may be altered or modified to improve affinity for the target, to humanize the target-binding sequence, to improve its production in cell culture, to reduce its immunogenicity in vivo, to create a multispecific antibody, among others. Such altered antibodies are specifically contemplated herein.

[0085] An“isolated” antibody is one that has been identified and separated and/or recovered from a component of its natural environment.

[0086] “Binding affinity” as used herein refers to the strength of the interaction between an antibody’s antigen binding site and its binding partner (e.g., an antigen). The affinity of an antibody for its antigen can generally be represented by the affinity constant (KA), the amount of antibody-antigen complex at equilibrium, or the equilibrium dissociation constant (KD). Affinity can be measured by any method as known in the art including, but not limited to, ELISAs, gel-shift assays, pull-down assays, equilibrium dialysis, analytical ultracentrifugation, surface plasmon resonance (SPR), isothermal titration calorimetry (ITC), and spectroscopic assays.

[0087] The term“patient,” or“subject” as used herein refers to a living organism suffering from or prone to a condition that can be prevented or treated by administration of a compound or composition as provided herein. Subjects include, but are not limited to, mammals (e.g., murines, simians, equines, bovines, porcines, canines, felines, and the like), and preferably are human.

[0088] The term“substantially homologous” or“substantially identical” means that a particular subject sequence, for example, a mutant sequence, varies from a reference sequence by one or more substitutions, deletions, or additions, the net effect of which does not result in an adverse functional dissimilarity between the reference and subject sequences. For purposes herein, a sequence having greater than 95 percent homology (identity), equivalent biological activity (although not necessarily equivalent strength of biological activity), and equivalent expression characteristics to a given sequence is considered to be substantially homologous (identical). For purposes of determining homology, truncation of the mature sequence should be disregarded. Exemplary IL-15 polypeptides for use herein include those sequences that are substantially homologous to SEQ ID NO: 1. SEQ ID NO:2 is nearly identical to SEQ ID NO: 1, with the exception that SEQ ID NO:2 has a methionine at the beginning of the sequence that is required for initiating translation in E. coli.

[0089] The term“fragment” means any protein or polypeptide having the amino acid sequence of a portion or fragment of the protein or polypeptide, e.g. an IL-15 moiety, and having the biological activity, or substantially the biological activity, of the protein or polypeptide, e.g. IL-15. Fragments include proteins or polypeptides produced by proteolytic degradation as well as proteins or polypeptides produced by chemical synthesis by methods routine in the art.

[0090] Amino acid residues in peptides are abbreviated as follows: Phenylalanine is

Phe or F; Leucine is Leu or L; Isoleucine is Ile or I; Methionine is Met or M; Valine is Val or V; Serine is Ser or S; Proline is Pro or P; Threonine is Thr or T; Alanine is Ala or A;

Tyrosine is Tyr or Y ; Histidine is His or H; Glutamine is Gln or Q; Asparagine is Asn or N; Lysine is Lys or K; Aspartic Acid is Asp or D; Glutamic Acid is Glu or E; Cysteine is Cys or C; Tryptophan is Trp or W; Arginine is Arg or R; and Glycine is Gly or G.

Overview

[0091] The instant disclosure is directed to, among other things, providing combinations, compositions, methods, and kits relating to the treatment of conditions such as cancer, comprising (a) a long-acting IL-15 receptor agonist, and (b) an antibody directed against a tumor antigen, where the tumor-directed antibody includes antibody-dependent cellular cytotoxicity (ADCC) as a mechanism of action. Such compositions and methods will ideally possess several advantageous and unpredictable features, such as, for example, at least one, if not more, of the following: an increased tumor clearance; increased and/or long-term survival of the patient; increased activity of one or both of the long-acting IL-15 receptor agonist and the antibody when administered in combination, when compared to either active agent administered singly, especially within a target tissue compartment; enhanced degranulation of NK cells; increased NK cell proliferation; increased NK cell viability;

increased T cell, e.g. CD8+ T cell, proliferation and/or increased T cell, e.g. CD8+ T cell, viability. Surprisingly, the Applicants have arrived at combination of a long-acting IL-15 receptor agonist and at least one antibody (such as a monoclonal antibody) directed against a tumor antigen that possesses a unique combination of advantageous properties, to be described in greater detail below and illustrated in the supporting examples.

[0092] The combination of a long-acting IL-15R agonist as described herein and targeted antibodies that mediate tumor killing by ADCC has been discovered to exhibit an enhanced immunotherapeutic effect. ADCC is a crucial mechanism in tumor depletion by certain tumor-targeted antibodies, wherein receptors on NK cells recognize the tumor cell-bound antibodies. Re-engagement of the NK cell receptor to the antibody triggers release of cytotoxic granules and/or cytokines to kill the tumor cells. It has been discovered that the long-acting IL-15R agonists described herein are effective to increase the efficacy of tumor targeting antibody therapies with an ADCC mechanism of action by expanding NK cells with increased cytotoxicity and/or other functional activation.

Therapeutic Combinations, Compositions and Methods of Use

[0093] In a first aspect, a method for treating a subject afflicted with a cancer or a tumor are described herein. The method comprises administering, together or separately, an antibody, or antigen-binding portion thereof, that binds specifically to a tumor antigen and a long-acting IL-15 receptor agonist. Due to the ability of the long-acting IL-15 receptor agonist to induce proliferation of NK cells, and to activate their tumor-cell killing capability, a combination therapeutic approach has been developed in which a long-acting IL-15 receptor agonist such as mono(methoxyPEG-N-butanamide)interleukin-l5 (also referred to as mono(mPEG-butanamide)interleukin-l5, mono(mPEG-butanamide)IL-l5, or mono-mPEG-SBA-IL15) is combined with a tumor-cell recognizing therapeutic monoclonal antibody to thereby generate an increased number of cell-killing activated NK cells that can also bind effectively to the antibody molecules, and may then be directed to the tumor cells by the antibodies to facilitate enhanced synergistic tumor cell killing. See, for example, the results described in the accompanying examples herein.

[0094] By way of clarity, with regard to the sequence of administering, wherein the term“administering” is used in this instance to refer to delivery of either the long-acting IL-15 receptor agonist or the tumor-directed antibody, the long-acting IL-15 receptor agonist and the tumor-directed antibody may be administered concurrently or sequentially and in any order. Moreover, treatment of either component of the combination may comprise a single cycle of therapy or may comprise multiple cycles. That is to say, following administration of the long-acting IL-15 agonist and administration of the tumor-directed antibody, additional rounds of therapy may include administration of the long acting IL-15 receptor agonist in

combination with administration of the tumor-directed antibody, administration of the long-acting IL-15 receptor agonist without further administration of the tumor-directed antibody, or administration of the tumor-directed antibody without further administration of the long-acting IL-15 receptor agonist, or any combination of the above administrations.

[0095] In a second aspect, a composition (or compositions) comprising an antibody, or antigen-binding portion thereof, that binds specifically to a tumor antigen and a long-acting IL-15 receptor agonist is described herein.

[0096] Generally, the antibodies as described herein are directed against a protein expressed on the cell surface of a cancer or tumor cell, referred to hereafter as a cancer antigen or tumor antigen. A number of cancer or tumor antigens are known in the art. Non limiting examples include phosphoproteins, transmembrane proteins, glycoproteins, gly colipids, and growth factors. Assays for determining whether a given compound can act as an antibody to any of the antigens or targets as described herein can be determined through routing experimentation by one of ordinary skill in the art.

[0097] In some embodiments, the antibody is an immunoglobulin G (IgG) type of antibody, typically found in human blood circulation.

[0098] In some embodiments, the antibody is an anti-CD 16, anti-CD 19, an anti- CD20, or an anti-CD38 antibody, that is, an antibody that specifically binds to CD16, CD19, CD20, CD30, CD38, or CD52.

[0099] The human CD 19 antigen is a 95 kDa glycoprotein belonging to the immunoglobulin (Ig) superfamily. CD19 is a biomarker for normal and neoplastic B cells as well as for follicular dendritic cells. CD19 is expressed from early stages of pre-B cell development through terminal differentiation, regulating B lymphocyte development and function. Expression of CD 19 is highly conserved on most B cell tumors including B cell lymphomas such as non-Hodgkin lymphoma. CD 19 is also expressed in most types of leukemia including B cell leukemias, acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), and Waldenstrom's Macroglobulinemia (WM). The majority of B cell malignances (lymphomas and leukemias) express CD 19 at normal to high levels. In embodiments, the antibody is an anti-CDl9 monoclonal antibody. Some exemplary anti-CD^ antibodies contemplated for use in the methods and compositions herein include, but are not limited to, and for example, an anti-B4-bR, BiTE (a bi-specific T-cell engaging antibody), MEDI-551 (Medlmmune, LLC), MOR-208 (MorphoSys AG), blinatumomab, a bi-specific anti-CDl9/CD3 BiTE® antibody, (Blincyto®, Amgen), coltuximab ravtansine (ImmunoGen Inc. and Sanofi), denintuzumab mafodotin (Seattle Genetics), taplitumomab

paptox (National Cancer Institute), XmAb 5871 (Amgen and Xencor Inc.), MDX-1342 (Medarex), AFM11 (Affimed Therapeutics), and the anti-CD 19 antibody described in U.S. Patent No. 8,691,952 (huB4, DI B4, Merck). In one or more embodiments, the combination of long-acting IL-15 receptor agonist and anti-CD 19 antibody are used in the treatment of B cell malignancies including, without limitation, non-Hodgkin lymphoma, acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemias (CLL), and Waldenstrom's

Macroglobulinemia (WM).

[00100] CD20 is a non-glycosolyated phosphoprotein of approximately 33-37kD that is expressed on the surface of almost all normal and malignant B cells. CD20 mAbs can exert an anti -tumor effect via Fab-mediated effects that involve the activation of effector mechanisms (Boross et al, Am J Cancer 2(6):676-690, 2012). In one or more embodiments, the antibody that is administered with a long-acting IL-15 receptor agonist as described herein is an anti-CD20 monoclonal antibody. Some exemplary anti-CD20 antibodies contemplated for use in the methods and compositions herein include rituximab (Rituxan®, Genentech), ofatumumab (Arzerra®, Genmab AC), ocrelizumab (Genentech), veltuzumab (Immunomedics), AME-133V (Eli Lilly), PR0131921 (Genentech), GA101 (Gly cart/Roche) ,ibritumomab tiuxetan (Zevalin), tositumomab (Bexxar), and obinutuzumab (Gazyva®, Genentech). In embodiments, the combination of a long-acting IL-15 receptor agonist such as described herein and an anti-CD20 antibody are used in the treatment of B cell malignancies including, without limitation, non-Hodgkin lymphoma, CLL, diffuse large B cell lymphoma (DLBCL), and follicular lymphoma.

[00101] CD38 is a 45 kDa type II transmembrane glycoprotein having receptor as well as enzyme functions. CD38 is generally expressed at low levels on various hematological and solid tissues, but expressed at high levels by plasma cells (shows especially broad and high expression levels in plasma cell tumors such as multiple myeloma (MM)). CD38 is also expressed in a subset of hematological tumors. In some further embodiments, the instant combination comprises administration of a long-acting IL-15 receptor agonist and an anti-CD38 monoclonal antibody. Some exemplary anti-CD38 antibodies contemplated for use in the methods and compositions provided herein include daratumumab (DARZALEX®, Janssen Biotech), isatuximab (SAR650984, Sanofi Oncology), and MOR202 (Morphosys).

In some further embodiments, the combination of a long-acting IL-15 receptor agonist and an anti-CD38 antibody are used in the treatment of a condition selected from multiple myeloma, CD38+ non-Hodgkin lymphoma, CDCLL, Waldenstrom’s macroglobulinemia, primary

systemic amyloidosis, mantle cell lymphoma, acute lymphoblastic leukemia, acute myeloid leukemia, NK cell leukemia, NK/T-cell lymphoma, and plasma cell leukemia.

[00102] In some additional embodiments, a therapeutic immuno-oncology based combination includes a long-acting IL-15 receptor agonist as described herein and an antibody directed to a glycoprotein selected from, without limitation, SLAMF7, EpCAM, gpA3, or folate binding protein (FBP). In embodiments, the antibody is an anti-SLAMF7 antibody, an anti-EpCAM antibody, an anti-gpA3 antibody, or an anti-FBP antibody.

[00103] The Signaling Lymphocyte Activation Molecule Family Member 7 (SLAMF7, previously known as CS1, CD319, CRACC) is a member of the signaling lymphocytic activation molecule family. SLAMF7 is expressed on immune cells, such as B cells, T cells, dendritic cells, NK T cells, and monocytes, as well as on multiple myeloma cells. In embodiments of the instant combination, the antibody is an anti-SLAMF7 monoclonal antibody. One exemplary anti-SLAMF7 antibody contemplated for use in the methods and compositions herein is elotuzumab (Emplicity™, Bristol-Myers Squibb). In embodiments, the combination of long-acting IL-15 receptor agonist and anti-SLAMF7 antibody are used in the treatment of multiple myeloma.

[00104] Epithelial cell adhesion molecule (EpCAM) is a transmembrane glycoprotein that is expressed by a number of epithelial cancer cells including tumors of gastrointestinal origin and some cancers of the genitourinary trace. EpCAM is expressed in, for example, human colon carcinoma, metastatic breast cancer, gallbladder cancer, ovarian cancer, and pancreatic cancer. In embodiments of the therapeutic combination provided herein, the antibody is an anti-EpCAM monoclonal antibody. Some exemplary anti- EpCAM antibodies contemplated for use in the methods and compositions herein include edrecolomab (Panorex, Creative Biolabs), ING-l (Xoma), 3622W94 (Creative Biolabs), and adecatumumab

(Amgen). In one or more embodiments, the combination of a long-acting IL-15 receptor agonist and an anti-EpCAM antibody are used in the treatment of human colon carcinoma, metastatic breast cancer, gallbladder cancer, ovarian cancer, adenocarcinomas, and pancreatic cancer.

[00105] In some further embodiments, the antibody is directed to a growth factor selected from, without limitation, vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor (VEGFR), and epidermal growth factor receptor (EGFR) for example. In some embodiments, the antibody is selected from an anti-VEGF antibody, an anti-VEGFR antibody, and an anti-EGFR antibody.

[00106] Vascular endothelial growth factor (VEGF) is a 27 kDa angiogenic signaling protein. VEGF is expressed in a most types of non-digestive and digestive cancers including pancreatic cancer, breast cancer, ovarian cancer, colorectal cancer, and lung cancer. Some exemplary anti- VEGF antibodies contemplated for use in the methods and compositions herein include bevacizumab (Avasatin®, Genentech, Inc.), ranibizumab, 2C3 and r84 (AT001, Affitech AS), and VEGF-Trap (aflibercept, Regeneron Pharmaceuticals, Inc.). In one or more embodiments, the combination of a long-acting IL-15 receptor agonist and an anti-VEGF antibody is used in the treatment of a cancer such as, for example, pancreatic cancer, breast cancer, ovarian cancer, colorectal cancer, metastatic renal cell carcinoma, and non-small cell lung cancer.

[00107] Vascular endothelial growth factor receptor (VEGFR) is a receptor tyrosine kinase (RTK) that can induce angiogenesis, increase cell growth and metastasis, etc. The VEGFR family has three main subtypes: VEGFR- 1, VEGFR-2 and VEGFR-3. Some exemplary anti-VEGFR antibodies contemplated for use in the methods and compositions herein include MF1/IMC-18F1 (ImClone Systems); IMC-1121B ImClone Systems), and DC101/IMC-1C11. In some further embodiments, the combination of a long-acting IL-15 receptor agonist and an anti-VEGFR antibody is used in the treatment of a cancer such as, for example, breast cancer or non-small cell lung cancer. In some embodiments, the anti-VEGFR antibody is used for an indication as recited above for an anti-VEGF antibody.

[00108] Epidermal growth factor receptors (EGFR) are a large family of receptor tyrosine kinases expressed in several types of cancer including breast, lung, esophageal, metastatic colorectal, and head and neck. Some exemplary anti-EGFR antibodies contemplated for use in the methods and compositions herein include cetuximab (Erbitux®, Lilly USA) and panitumumab (Vectibix®, Amgen). In one or more particular embodiments, the antibody is an anti-human epidermal growth factor receptor 2 antibody (anti-HER2). Some exemplary anti-HER2 antibodies contemplated for use in the methods and

compositions herein include the humanized monoclonal antibody trastuzumab (Herceptin®, Genentech, Inc.) and/or pertuzumab (Perjeta®, Genentech, Inc.). In some related embodiments, the combination of a long-acting IL-15 receptor agonist and an anti-EGFR antibody is used in the treatment of a cancer such as breast ( e.g . metastatic breast cancer), lung, esophageal, metastatic colorectal, and head and neck cancers.

[00109] Also contemplated for use in the methods and combinations provided herein is an anti-BCMA (B-cell maturation antigen, also referred to as CD269) antibody. BCMA is a member of the tumor necrosis factor receptor (TNFR) superfamily. BCMA binds B-cell

activating factor (BAFF) and a proliferation inducing ligand (APRIL). Among non-malignant cells, BCMA has been reported to be expressed mostly in plasma cells and subsets of mature B-cells. BCMA RNA has been detected in multiple myeloma cells, and BCMA protein has been detected on the surface of plasma cells from multiple myeloma patients. BCMA is expressed or overexpressed by various human cancers. Examples of cancers that express or overexpress BCMA include, but are not limited to, Burkitf s lymphoma, diffuse large B-cell lymphoma (DLBCL) lymphoma, acute lymphocytic leukemia (ALL) lymphoma, Hodgkin's lymphoma and multiple myeloma. Exemplary anti-BCMA antibodies are described, for example, in U.S. Patent Publication Nos. 20120082661, 20170051068, and 20180318435 (the contents each of which is incorporated herein by reference in its entirety). Exemplary anti-BCMA antibodies include BCMAxXD3, described in Pillarisetti, K., et al, Blood, 2016, 128:2116, and the humanized antibody portion of the anti-BCMA antibody drug conjugate, GSK2857916.

[00110] In some embodiments, the antibody may simultaneously bind more than one specific antigen, e.g. a bispecific antibody.

[00111] In some embodiments, the antibody is one that cross-competes for binding with any of the antibodies as described above. An antibody that cross-competes with any one of the above-referenced antibodies is expected to have similar or the same functional properties.

[00112] In some embodiments, the antibodies for use herein are the antigen-binding portion of any of the antibodies as described above as it is well known in the art that the antigen-binding function of an antibody may be performed by fragments of the full-length antibody.

[00113] Turning now to the long-acting IL-15 receptor (IL-15R) agonist, generally, a preferred long-acting IL-15 receptor agonist or a pharmaceutically acceptable salt form thereof comprises a single linear polyalkylene oxide (e.g. polyethylene glycol or“PEG”) moiety stably covalently attached to an IL-15 amino group via an amide linkage. Intervening between the PEG moiety and the stable amide linkage to an IL-15 amino group is a linear unsubstituted alkylene group (~CH2~)m having from 2 to 5 carbon atoms (i.e., m is 2, 3, 4, or 5). In one or more preferred embodiments, m is 3 such that the stable amide linkage is a butanamide.

[00114] In one or more preferred embodiments, the long-acting IL-15R agonist is (methoxyPEG-N-butanamide)2o-60kDinterleukin-l5, more preferably (methoxyPEG-N-butanamide)20-40kDinterleukin-l5, and even more preferably (methoxyPEG-N-

butanamide)40kDinterleukin-l5. In one or more preferred embodiments, the long-acting IL-15R agonist is mono(methoxyPEG-N-butanamide)2o-60kDinterleukin-l5, more preferably mono(methoxyPEG-N-butanamide)2o-40kDinterleukin-l5, and even more preferably mono(methoxyPEG-N-butanamide)40kDinterleukin-l5. In one preferred embodiment, the long-acting IL-15R agonist is mono(methoxyPEG-N-butanamide)40kDinterleukin-l5.

[00115] IL-15R agonists described herein having a structure encompassed by Formula (I), and in particular mono(methoxyPEG-N-butanamide)40kDinterleukin-l5, retain binding affinity to the IL-15 receptor alpha (IL-l5Ra) subunit as well as the beta (b) and gamma (g) subunits. The long-acting IL-15R agonists described herein present to the I L-2 I L- 15 Ebg complex on the same (cis) or adjacent cells (trans). Engagement of the IL-2/IL-15Rbg complex by the long-acting IL-15R agonists described herein can induce the Janus kinase/signal transducer and activator of transcription-5 (JAK-STAT5) pathways, which increases T cell proliferation, survival and/or activity. The long-acting IL-15R agonist further significantly enhances proliferation and activation of CD8+ T cells. The long-acting IL-15R agonists preferably have decreased clearance as compared to corresponding unmodified IL-15R agonists. Without being limited by theory, it is postulated that attachment of the PEG enlarges the hydrodynamic volume of the IL-15 moiety to result in a longer effective half-life, lower maximum peak concentration (Cmax), and/or reduced clearance in comparison to unconjugated rhIL-l5. The long-acting IL-15R agonists described herein provide sustained IL-15 biological activity without the need for daily dosing.

[00116] When considering the IL-15 moiety, the term“IL-15 moiety” refers to the IL-15 moiety prior to conjugation as well as to the IL-15 moiety following attachment to a non-peptidic, water-soluble polymer such as PEG. While specific reference is made to PEG hereafter as the non-peptidic, water-soluble polymer below, it will be understood that the disclosure relates generally to a non-peptidic, water-soluble polymer or poly(alkylene glycol). It will be understood, however, that when the original IL-15 moiety is attached to a polyethylene glycol moiety, the IL-15 moiety is slightly altered due to the presence of one or more covalent bonds associated with linkage to the polymer(s).

[00117] The IL-15 moiety can be derived from non-recombinant methods and from recombinant methods, and the disclosure is not limited in this regard. In addition, the IL-15 moiety can be derived from human sources, animal sources (including insects), fungi sources (including yeasts), and plant sources.

[00118] The IL-15 moiety can be obtained according to the procedures described by, for example, Grabstein et al. (Grabstein et al. (1994) Science 264:965-968). The IL-15 moiety can also be prepared using recombinant methods, such as, for example, those described in EP Patent No. 0 772 624 B2 to Immunex Corporation. Alternatively, the IL-15 moiety can be purchased commercially from, for example, GenScript USA Inc. (Piscataway NJ) and Peprotech (Rockyhill, NJ).

[00119] The IL-15 moiety can be expressed in bacterial (e.g., E. coli, see, for example, Fischer et al. (1995) Biotechnol. Appl. Biotechnol. 2l_(3):295-3l l), mammalian (see, for example, Kronman et al. (1992) Gene 121 :295-304). yeast (e.g., Pichia pastoris, see, for example, Morel et al. (1997) Biochem. J. 328(1): 121-129), and plant (see, for example, Mor et al. (2001) Biotechnol. Bioeng. 75(3):259-266) expression systems. The expression can occur via exogenous expression (when the host cell naturally contains the desired genetic coding) or via endogenous expression.

[00120] Further methods of preparation and/or purification of an IL-15 moiety are described in PCT Application No. PCT/US2018/032817, which is incorporated by reference herein in its entirety.

[00121] Depending on the system used to express proteins having IL-15 activity, the IL-15 moiety can be unglycosylated or glycosylated and either may be used. In one or more embodiments, the IL-15 moiety is unglycosylated.

[00122] The IL-15 moiety can advantageously be modified to include and/or substitute one or more amino acid residues such as, for example, lysine, cysteine and/or arginine, in order to provide facile attachment of the polymer to an atom within the side chain of the amino acid. An example of substitution of an IL-15 moiety is described in U.S. Patent No. 6,177,079. In addition, the IL-15 moiety can be modified to include a non-naturally occurring amino acid residue. Techniques for adding amino acid residues and non-naturally occurring amino acid residues are well known to those of ordinary skill in the art. Reference is made to J. March, Advanced Organic Chemistry: Reactions Mechanisms and Structure, 4th Ed. (New York: Wiley-Interscience, 1992), and Bioinformatics for Geneticists (eds. Michael R. Bames and Ian C Gray), 2003 John Wiley & Sons, Ltd, Chapter 14, Amino Acid Properties and Consequences of Substitutions, Betts, M.J., and Russell, R. B.

[00123] Additional suitable modifications and methods for such modification of the IL-15 moiety are described in PCT Application No. PCT/US2018/032817, which is incorporated by reference herein in its entirety. Exemplary modifications include attachment of a functional group (other than through addition of a functional group-containing amino acid residue), such as, for example, inclusion of a thiol group, an N-terminal alpha carbon, one or more carbohydrate moieties, an aldehyde group, or a ketone group. In some embodiments, it is preferred that the IL-15 moiety is not modified to include one or more of a thiol group, an N-terminal alpha carbon, a carbohydrate, an aldehyde group, or a ketone group.

[00124] Exemplary IL-15 moieties are described herein, in the literature, and in, for example, U.S. Patent Application Publication No. US 2006/0104945, Pettit et al. (1997) J. Biol. Chem. 272(4):2312-2318, Wong et al. (2013) Oncolmmunology 2(11), e26442: l-3, and PCT Application No. PCT/US2018/032817, each of which is incorporated by reference herein in its entirety. Preferred IL-15 moieties include those having an amino acid sequence comprising sequences selected from the group consisting of SEQ ID NOs: 1 through 3, and sequences substantially homologous thereto (wherein even if SEQ ID NOs 2 and 3, and sequences substantially homologous thereto do not meet the in vitro activity standard of an IL-15 moiety provided herein, it will be understood for purposes of the present disclosure that these sequences are also understood to be“IL-15 moieties”). A preferred IL-15 moiety has an amino acid sequence corresponding to SEQ ID NO: 1. In some embodiments, the IL-15 moiety is a functional homolog having at least about 85% or at least about 90% identity with any one of SEQ ID NOs: 1-3. In some embodiments, the IL-15 moiety is a functional homolog having at least about 95%, 98% or 99% identity with any one of SEQ ID NOs: 1-3.

[00125] In some instances, the IL-15 moiety will be in a“monomer” form, wherein a single expression of the corresponding peptide is organized into a discrete unit. In other instances, the IL-15 moiety will be in the form of a“dimer” (e.g., a dimer of recombinant IL-15) wherein two monomer forms of the protein are associated to each other.

[00126] In addition, precursor forms of IL-15 can be used as the IL-15 moiety. An exemplary precursor form of IL-15 has the sequence of SEQ ID NO: 3.

[00127] In some embodiments, the long-acting IL-15R agonist is a PEGylated IL-15 molecule as described in U.S. Published Application No. 2018/0360977, and specifically a multi-arm PEG IL-15 as described therein.

[00128] In some embodiments, the IL-15 moiety is an IL-15 mutein or other IL-15 related molecule as described in U.S. Patent No. 10,350,270.

[00129] Truncated versions, hybrid variants, and peptide mimetics of any of the foregoing sequences can also serve as the IL-15 moiety. Biologically active fragments, deletion variants, substitution variants or addition variants of any of the foregoing that maintain at least some degree of IL-15 activity can also serve as an IL-15 moiety.

[00130] For any given peptide, protein moiety or conjugate, it is possible to determine whether that peptide, protein moiety or conjugate has IL-15 activity. Various methods for determining in vitro IL-15 activity are described in the art. An exemplary approach is based on a pSTAT assay. Briefly, if an IL- 15 -dependent CTLL-2 cell is exposed to a test article having IL-15 activity, initiation of a signaling cascade results that includes the

phosphorylation of STAT5 at tyrosine residue 694 (Tyr694), which can be quantitatively measured. Assay protocols and kits are known and include, for example, the MSD

Phospho(Tyr694)/Total STATa,b Whole Cell Lysate Kit (Meso Seal Diagnostics, LLC, Gaithersburg, MD). For example, using this approach, a proposed IL-15 moiety that exhibits a pSTAT5 EC50 value of no more than about 300 ng/mL (more preferably no more than about 150 ng/mL) at least one of 5 minutes or at 10 minutes is considered an“IL-15 moiety” in connection with the present disclosure. It is preferred, however, that the IL-15 moiety used is more potent (e.g., having a pSTAT5 EC50 value of less than 150 ng/mL at one of least 5 minutes or 10 minutes, such as less than about 1 ng/mL, and even more preferably less than 0.5 ng/mL at least one of 5 minutes or at 10 minutes).

[00131] Other methodologies known in the art can also be used to assess IL-15 function, including electrometry, spectrophotometry, chromatography, and radiometric methodologies. See, for example, Ring et al. (2012) Nat. Immunol. 13(12): 1187-1195 for one such additional type of assay.

[00132] Assays for use in connection with measuring the activity of an IL-15 moiety can also be used to measure the activity of the long-acting IL-15 receptor agonists described herein. See, for example, the supporting examples provided herein.

[00133] A compound is considered to be a long-acting, IL-15 receptor agonist in accordance with the present disclosure so long as, following administration to a subject, the agonist exhibits IL-15R agonism in vivo for an amount of time that is longer than would be the case for administration of IL-15. Conventional approaches, such as those involving radiolabeling a compound, administering the compound in vivo, and determining its clearance, can be used to assess whether a compound proposed to be a long-acting, IL-15 receptor agonist is“long-acting” (i.e., has a clearance that is longer than that of IL-15 administered in the same in vivo system). For the purposes herein, the long-acting nature of a long-acting IL-15 receptor agonist may be, and is typically determined using flow cytometry to measure STAT5 phosphorylation in lymphocytes at various time points after

administration of the agonist to be evaluated in mice. As a reference, the signal is lost by around 24 hours with IL-15, but is sustained for a period greater than that for a long-acting IL-15 agonist.

[00134] A preferred long-acting IL-15 receptor agonist will generally comprise a single linear PEG (polyethylene glycol) moiety stably covalently attached to an IL-15 amino group via an amide linkage. Intervening between the PEG moiety and the stable amide linkage to an IL-15 amino group is a linear unsubstituted alkylene group (~CH2~)m having from 2 to 5 carbon atoms (i.e., where m=2, 3, 4, or 5).

[00135] For example, in some embodiments, the unsubstituted alkylene group is (~CH2~)2; or, in some additional embodiments, the unsubstituted alkylene group is (~CH2~)3; in yet some further embodiments, the unsubstituted alkylene group is (-CFh- in yet some further embodiments, the unsubstituted alkylene group is the unsubstituted alkylene group is (~CH2~)5.

[00136] For example, in some embodiments, the long-acting IL-15 receptor agonist has the following structure:

Formula (I)

wherein IL-15 is an interleukin- 15 moiety, n is an integer from about 150 to about 3,000; m is an integer from 2-5 (e.g., 2, 3, 4, or 5) and n’ is 1. In Formula I (and in similar formulae provided herein) the ~NH~ in the structure represents an amino group of the IL-15 moiety. Formula (I) may also be depicted as follows, where the parentheses are shifted to reflect a

terminal PEG methoxy group,
, and the two formulae may be used interchangeably. Illustrative exemplary compounds include the following encompassed by Formula (I):

Formula (lb)

Formula (Id).

[00137] In some preferred embodiments, the long-acting IL-15 receptor agonist corresponds to Formula (la) or Formula (lb). In some particularly preferred embodiments, the long-acting IL-15 receptor agonist corresponds to Formula (lb).

[00138] In some further embodiments, in reference to the structures and formulae described herein, n is an integer from about 200 to about 2000, or from about 400 to about 1300, or from about 450 to about 1200. That is to say, in some embodiments, n is an integer from about 200 to about 2000. In yet some further embodiments, n is an integer from about 400 to about 1300. In yet some further embodiments, n is an integer from about 450 to about

1200

[00139] PEGs having a molecular weight corresponding to any one of the foregoing ranges of n values are generally preferred.

[00140] In one or more additional embodiments, n is an integer having a value that corresponds to a polyethylene glycol polymer having a weight average molecular weight selected from the group consisting of about 10,000 daltons (where n is -227), or about 15,000 daltons (where n is -340), or about 20,000 daltons (where n is -454), or about 25,000 daltons (where n is -568), or about 30,000 daltons (where n is -681), or about 40,000 daltons (where n is -907-909, e.g., -909), or about 50,000 daltons (where n is -1136) or even about 60,000 daltons (where n is -1364) or greater.

IT IS CLAIMED:

1. A method of treating a subject having cancer, the method comprising:

administering to the subject

(a) a long-acting IL-15 receptor agonist having a structure:

Formula (I)

wherein IL-15 is an interleukin- 15 moiety, n is an integer from about 150 to about 3,000, m is an integer selected from 2, 3, 4, and 5, n’ is 1, and ~NH~ represents an amino group of the IL-15 moiety; and

(b) a monoclonal antibody that binds specifically to a tumor antigen selected from a phosphoprotein, a transmembrane protein, a glycoprotein, a glycolipid, and a growth factor, , wherein the monoclonal antibody has antibody dependent cellular cytotoxicity (ADCC) as a mechanism of action;

wherein steps (a) and (b) are carried out concurrently or sequentially and in any order.

2. The method of claim 1, wherein the long-acting IL-15 receptor agonist is a

pharmaceutically acceptable salt.

3. The method of claim 1 or 2, wherein (m) in Formula (I) is 2 or 3.

4. The method of any one of claims 1-3, wherein (m) in Formula (I) is 3.

5. The method of any one of claims 1-4, wherein (n) in Formula (I) has a value of about

909.

6. The method of any one of claims 1-5, wherein the cancer is a solid cancer.

7. The method of claim 6, wherein the solid cancer is selected from the group consisting of breast cancer, ovarian cancer, colon cancer, colorectal cancer, gastric cancer, malignant melanoma, liver cancer, small cell lung cancer, non-small cell lung cancer, thyroid cancers, kidney cancer, cancer of the bile duct, brain cancer, cervical cancer, maxillary sinus cancer, bladder cancer, esophageal cancer, Hodgkin's disease and adrenocortical cancer, including metastatic forms of any of the foregoing.

8. The method of any one of claims 1-5, wherein the cancer is a hematological

malignancy.

9. The method of claim 8, wherein the hematological malignancy is selected from the group consisting of multiple myeloma, non-Hodgkin lymphoma, leukemia and lymphoma.

10. The method of any one of claims 1-9, wherein step (a) is carried out prior to step (b).

11. The method of any one of claims 1-9, wherein step (b) is carried out prior to step (a).

12. The method of any one of claims 1-9, wherein step (a) and step (b) are carried out concurrently or substantially concurrently.

13. The method of any one of claims 1-12, wherein said administering is effective to

stimulate NK activation to an extent greater than observed when the long-acting IL-15 receptor agonist is administered as a single agent, as measured in a suitable animal model.

14. The method of any one of claims 1-13, wherein said administering is effective to

stimulate NK proliferation to an extent greater than observed when the long-acting IL- 15 receptor agonist is administered as a single agent, as measured in a suitable animal model.

15. The method of any one of claims 1-14, wherein said administering is effective to

support CD8+ T-cell survival and memory formation to an extent greater than observed when the long-acting IL-15 receptor agonist is administered as a single agent, as measured in a suitable animal model.

16. The method of any one of claims 1-15, wherein the long-acting IL-15 receptor agonist is administered subcutaneously.

17. The method of any one of claims 1-16, wherein the monoclonal antibody is

administered intravenously.

18. The method of any one of claims 1-17, wherein the monoclonal antibody is selected from an anti-CDl9 antibody, an anti-CD20 antibody, and an anti-CD38 antibody.

19. The method of any one of claims 1-17, wherein the monoclonal antibody that binds specifically to a glycoprotein is selected from an anti-SLAMF7 antibody, an anti- EpCAM antibody, an anti-gpA3 antibody 3, and an anti-FBP antibody.

20. The method of any one of claims 1-17, wherein the monoclonal antibody that binds specifically to a growth factor is selected from an anti-VEGF antibody, an anti-VEGFR antibody, and an anti-EGFR antibody.

21. The method of any one of claims 1-17, wherein the monoclonal antibody is an IgG antibody.

22 The method of any one of claims 1-17, wherein the monoclonal antibody is selected from the group consisting of daratumumab, rituximab, cetuximab and trastuzumab.

23. A therapeutic combination for use in treating cancer, comprising

(a) a long-acting IL-15 receptor agonist having a structure:

Formula (I)

wherein IL-15 is an interleukin- 15 moiety, n is an integer from about 150 to about 3,000, m is an integer selected from 2, 3, 4, and 5, n’ is 1, and ~NH~ represents an amino group of the IL-15 moiety; and

(b) a monoclonal antibody that binds specifically to a tumor antigen selected from a phosphoprotein, a transmembrane protein, a glycoprotein, a glycobpid, and a growth factor, wherein the monoclonal antibody includes antibody dependent cellular cytotoxicity (ADCC) as a mechanism of action.

24. The therapeutic combination of claim 23, wherein the long-acting receptor agonist is a pharmaceutically acceptable salt.

25. The therapeutic combination of claim 23 or 24, wherein the long-acting IL-15 receptor agonist has a structure as described in any one of claims 3, 4, or 5.

26. A kit comprising the therapeutic combination of any one of claims 23-25, accompanied by instructions for use, wherein the long-acting IL-15 receptor agonist and the monoclonal antibody are each contained in one or more individual unit dosage forms.

27. Use of a long-acting receptor agonist to enhance NK-cell mediated antibody-dependent cellular toxicity when administered with an anti-tumor antibody.