WO2025048860A1 - Ox40 agonist therapy - Google Patents

Abstract

Provided herein are OX40 agonists and uses thereof, including methods of treating cancer comprising administering an OX40 agonist, alone or in combination with a second therapeutic agent.

Description

Attorney Docket No.01202-0062-00PCT OX40 AGONIST THERAPY FIELD [0001] The present invention relates to methods of treatment using OX40 agonists, alone and in combination with a second therapeutic agent. Such methods include, but are not limited to, methods of treating cancer. In some embodiments, the OX40 agonists are multivalent OX40- binding polypeptides, such as hexavalent OX40-binding polypeptides. BACKGROUND [0002] The tumor necrosis factor receptor superfamily (TNFRSF) includes several structurally related cell surface receptors. Activation by multimeric ligands is a common feature of many of these receptors, and such activation has therapeutic utility in numerous pathologies if activated properly. Effective agonism of this receptor family may require higher order clustering than is achieved using traditional bivalent antibodies. [0003] OX40 (TNFRSF4, CD134) is a member of the TNF receptor superfamily, and is expressed on the surface of T cells 24 to 72 hours following T cell activation. Antigen presenting cells in close proximity to activated T cells present OX40 ligand (OX40L) on their surface, which binds and clusters OX40 on T cells sending a co-stimulatory signal that increases T-cell expansion and enhances effector T-cell differentiation. Activation of OX40 therefore serves to maintain an immune response, e.g., by enhancing survival and function of T cells. [0004] There exists a therapeutic need for potent agonists of OX40 and therapeutic methods using them. SUMMARY [0005] The present invention relates to the use of an OX40 agonist alone or in combination therapy for treating diseases such as cancer. Certain nonlimiting embodiments include: 1. A method of treating cancer comprising administering to a subject with cancer an OX40 agonist at a dose of about 0.1 mg/kg to about 0.3 mg/kg once about every three weeks. 2. A method of treating cancer comprising administering to a subject with cancer: a) an OX40 agonist at a dose of about 0.1 mg/kg to about 0.3 mg/kg once about every three weeks; and b) an anti-PD-1 antibody once about every three weeks; wherein the OX40 agonist comprises three VHH domains that bind OX40 and an Fc region, wherein each VHH domain comprises a CDR1 comprising the amino acid Attorney Docket No.01202-0062-00PCT sequence of SEQ ID NO: 2, a CDR2 comprising the amino acid sequence of SEQ ID NO: 3, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 4. 3. The method of embodiment 1 or embodiment 2, wherein the OX40 agonist is administered at a dose of 0.1 mg/kg. 4. The method of embodiment 1 or embodiment 2, wherein the OX40 agonist is administered at a dose of 0.3 mg/kg. 5. The method of any one of embodiments 1-5, wherein the OX40 agonist and the anti-PD-1 antibody are administered on the same day. 6. The method of any one of embodiments 1-5, wherein the OX40 agonist is administered prior to administration of the anti-PD-1 antibody. 7. The method of any one of embodiments 1-5, wherein the anti-PD-1 antibody administered prior to administration of the OX40 agonist. 8. A method of treating cancer comprising administering to a subject with cancer: a) a priming dose of an OX40 agonist, wherein the priming dose is about 0.3 mg/kg; b) a maintenance dose of an OX40 agonist, wherein the maintenance dose is about 0.1 mg/kg, wherein the first maintenance dose is administered about three weeks after the priming dose of the OX40 agonist, and wherein the maintenance dose is administered once about once every three weeks; and c) an-anti-PD-1 antibody, wherein the first dose of the anti-PD-1 antibody is administered about three weeks after the priming dose of the OX40 agonist, wherein the anti-PD-1 antibody is administered once about every three weeks; wherein the OX40 agonist comprises three VHH domains that bind OX40 and an Fc region, wherein each VHH domain comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 2, a CDR2 comprising the amino acid sequence of SEQ ID NO: 3, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 4. 9. The method of embodiment 7, wherein the method comprises administering one priming dose. 10. The method of embodiment 8 or embodiment 9, wherein the maintenance dose of the OX40 agonist and the anti-PD-1 antibody are administered on the same day. 11. The method of any one of embodiments 8-10, wherein the maintenance dose of the OX40 agonist is administered prior to administration of the anti-PD-1 antibody. 12. The method of any one of embodiments 8-10, wherein the anti-PD-1 antibody administered prior to administration of the maintenance dose of the OX40 agonist. 13. The method of any one of embodiments 2-12, wherein the anti-PD-1 antibody is pembrolizumab, nivolumab, dostarlimab, retifanlimab, cemiplimab, or toripalimab. Attorney Docket No.01202-0062-00PCT 14. The method of any one of embodiments 2-13, wherein the anti-PD-1 antibody is pembrolizumab. 15. The method of any one of embodiments 2-13, wherein the anti-PD-1 antibody is nivolumab. 16. The method of any one of embodiments 2-13, wherein the anti-PD-1 antibody is dostarlimab. 17. The method of any one of embodiments 2-13, wherein the anti-PD-1 antibody is retifanlimab. 18. The method of any one of embodiments 2-13, wherein the anti-PD-1 antibody is cemiplimab. 19. The method of any one of embodiments 2-13, wherein the anti-PD-1 antibody is toripalimab. 20. The method of embodiments 2-19, wherein the anti-PD-1 antibody is administered at a dose of about 150 mg to about 600 mg. 21. The method of any one of embodiments 2-20, wherein the anti-PD-1 antibody is administered at a dose of about 200 mg, about 240 mg, about 350 mg, about 375 mg, or about 500 mg. 22. The method of any one of embodiments 2-13, wherein the anti-PD-1 antibody is pembrolizumab and is administered at a dose of about 200 mg. 23. The method of any one of embodiments 2-13, wherein the anti-PD-1 antibody is nivolumab and is administered at a dose of about 240 mg. 24. The method of any one of embodiments 2-13, wherein the anti-PD-1 antibody is toripalimab and is administered at a dose of about 240 mg. 25. The method of any one of embodiments 2-13, wherein the anti-PD-1 antibody is cemiplimab and is administered at a dose of about 350 mg. 26. The method of any one of embodiments 2-13, wherein the anti-PD-1 antibody is retifanlimab and is administered at a dose of about 375 mg. 27. The method of any one of embodiments 2-13, wherein the anti-PD-1 antibody is dostarlimab and is administered at a dose of about 500 mg. 28. A method of treating cancer comprising administering to a subject with cancer: a) an OX40 agonist at a dose of 0.3 mg/kg once about every 6 weeks; and b) an anti-PD-1 antibody once about every 6 weeks; wherein the OX40 agonist and anti-PD-1 antibody are administered on an alternating schedule about three weeks apart, and wherein the OX40 agonist comprises three VHH domains that bind OX40 and an Fc region, wherein each VHH domain comprises a CDR1 comprising the amino Attorney Docket No.01202-0062-00PCT acid sequence of SEQ ID NO: 2, a CDR2 comprising the amino acid sequence of SEQ ID NO: 3, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 4. 29. The method of embodiment 28, wherein the first dose of the OX40 agonist is administered about three weeks prior to the administration of the anti-PD-1 antibody. 30. The method of embodiment 28, wherein the first dose of anti-PD-1 antibody is administered about three weeks prior to the administration of the OX40 agonist. 31. The method of any one of embodiments 28-30, wherein the anti-PD-1 antibody is pembrolizumab, nivolumab, dostarlimab, retifanlimab, cemiplimab, or toripalimab. 32. The method of any one of embodiments 28-30, wherein the anti-PD-1 antibody is pembrolizumab. 33. The method of any one of embodiments 28-30, wherein the anti-PD-1 antibody is nivolumab. 34. The method of any one of embodiments 28-30, wherein the anti-PD-1 antibody is dostarlimab. 35. The method of any one of embodiments 28-30, wherein the anti-PD-1 antibody is retifanlimab. 36. The method of any one of embodiments 28-30, wherein the anti-PD-1 antibody is cemiplimab. 37. The method of any one of embodiments 28-30, wherein the anti-PD-1 antibody is toripalimab. 38. The method of any one of embodiments 28-37, wherein the anti-PD-1 antibody is administered at a dose of about 300 mg to about 1200 mg. 39. The method of any one of embodiments 28-38, wherein the anti-PD-1 antibody is administered at a dose of about 400 mg, about 480 mg, about 700 mg, about 750 mg, or about 1000 mg. 40. The method of any one of embodiments 28-30, wherein the anti-PD-1 antibody is pembrolizumab and is administered at a dose of about 400 mg. 41. The method of any one of embodiments 28-30, wherein the anti-PD-1 antibody is nivolumab and is administered at a dose of about 480 mg. 42. The method of any one of embodiments 28-30, wherein the anti-PD-1 antibody is toripalimab and is administered at a dose of about 240 mg. 43. The method of any one of embodiments 28-30, wherein the anti-PD-1 antibody is cemiplimab and is administered at a dose of about 700 mg. 44. The method of any one of embodiments 28-30, wherein the anti-PD-1 antibody is retifanlimab and is administered at a dose of about 750 mg Attorney Docket No.01202-0062-00PCT 45. The method of any one of embodiments 28-30, wherein the anti-PD-1 antibody is dostarlimab and is administered at a dose of about 1000 mg. 46. The method of any one of embodiments 2-45, wherein the anti-PD-1 antibody is administered by IV infusion. 47. The method of any one of the preceding embodiments, wherein the OX40 agonist is administered by intravenous (IV) infusion. 48. The method of any one of the preceding embodiments, wherein the cancer is basal cell carcinoma, biliary tract cancer; bladder cancer; bone cancer; brain and central nervous system cancer; breast cancer; cancer of the peritoneum; cervical cancer; choriocarcinoma; colon and rectum cancer; connective tissue cancer; cancer of the digestive system; endometrial cancer; esophageal cancer; eye cancer; cancer of the head and neck; or gastroesophageal junction adenocarcinoma (G/GEA); glioblastoma; hepatic carcinoma; hepatoma; intra-epithelial neoplasm; kidney or renal cancer; larynx cancer; liver cancer; lung cancer; small-cell lung cancer; non-small cell lung cancer (NSCLC); adenocarcinoma of the lung; squamous carcinoma of the lung; melanoma; myeloma; neuroblastoma; oral cavity cancer; ovarian cancer; pancreatic cancer; prostate cancer; retinoblastoma; rhabdomyosarcoma; rectal cancer; cancer of the respiratory system; salivary gland carcinoma; sarcoma; skin cancer; squamous cell cancer; stomach cancer; testicular cancer; thyroid cancer; uterine or endometrial cancer; cancer of the urinary system; vulval cancer; lymphoma; Hodgkin’s lymphoma; non-Hodgkin’s lymphoma; B- cell lymphoma; low grade/follicular non-Hodgkin's lymphoma (NHL); small lymphocytic (SL) NHL; intermediate grade/follicular NHL; intermediate grade diffuse NHL; high grade immunoblastic NHL; high grade lymphoblastic NHL; high grade small non-cleaved cell NHL; bulky disease NHL; mantle cell lymphoma; AIDS-related lymphoma; Waldenstrom's macroglobulinemia; chronic lymphocytic leukemia (CLL); acute lymphoblastic leukemia (ALL); Hairy cell leukemia; or chronic myeloblastic leukemia. 49. The method of any one of the preceding embodiments, wherein the cancer is NSCLC, melanoma (including cutaneous melanoma, mucosal melanoma, and ocular/uveal melanoma), head and neck squamous cell carcinoma (HNSCC), gastric or gastroesophageal junction adenocarcinoma (G/GEA), renal cell carcinoma (RCC), or urothelial (transitional) cell carcinoma (TCC). 50. The method of any one of the preceding embodiments, wherein the cancer is microsatellite instability (MSI) high, regardless of histology. 51. The method of any one of the preceding embodiments, wherein the cancer is tumor mutational burden (TMB) high, regardless of histology. Attorney Docket No.01202-0062-00PCT 52. The method of any one of the preceding embodiments, wherein the cancer is deficient for at least one mismatch repair (MMR) protein, regardless of histology. 53. The method of any one of embodiments preceding embodiments, wherein the subject has received previous treatment with a checkpoint inhibitor. 54. The method of any one of embodiments 1-52, wherein the subject is checkpoint inhibitor naïve. 55. The method of any one of the preceding embodiments, wherein a sample of the cancer has been determined to express PD-L1. 56. The method of embodiment 55, wherein the sample of the cancer has a combined positive score (CPS) ≥ 1%. 57. The method of embodiment 55 or embodiment 56, wherein the sample of the cancer has a tumor proportion score (TPS) ≥ 1%. 58. The method of any one of the preceding embodiments, wherein each VHH domain of the OX40 agonist is humanized. 59. The method of any one of the preceding embodiments, wherein each VHH domain of the OX40 agonist comprises the amino acid sequence of SEQ ID NO: 1. 60. The method of any one of the preceding embodiments, wherein the OX40 agonist comprises the amino acid sequence of SEQ ID NO: 9. 61. The method of any one of the preceding embodiments, wherein the Fc domain of the OX40 agonist comprises an amino acid sequence selected from SEQ ID NOs: 12-15. 62. The method of embodiment 61, wherein the Fc domain comprises the amino acid sequence of SEQ ID NO: 12 or 13. 63. The method of any one of the preceding embodiments, wherein the OX40 agonist comprises the amino acid sequence of SEQ ID NO: 10 or 11. 64. The method of any one of the preceding embodiments, wherein the OX40 agonist is a homodimer under physiological conditions. 65. The method of any one of the preceding embodiments, wherein the OX40 agonist is INBRX-106. 66. The method of any one of the preceding embodiments, wherein the subject is treated for at least 6 weeks, at least 12 weeks, at least 18 weeks, at least 24 weeks, at least 30 weeks, at least 36 weeks, at least 42 weeks, or at least 48 weeks. BRIEF DESCRIPTION OF THE FIGURES Attorney Docket No.01202-0062-00PCT [0006] FIG.1 shows an increase in CD4⁺ T and CD8⁺ T cell proliferation following co- stimulation of human T cells with anti-CD3 antibody and hexavalent 3x1D10v6-Fc (“No Antibody” indicates anti-CD3 antibody stimulation without hexavalent 3x1D10v1-Fc). [0007] FIG.2 shows increased CD4⁺ and CD8⁺ T cell proliferation (top two panels), increased percentages of CD25⁺ CD4⁺ and CD25⁺ CD8⁺ T cells (middle two panels), and increased percentages of CD71⁺ CD4⁺ and CD71⁺ CD8⁺ T cells (bottom two panels), following co- stimulation of T cells from 10 healthy donors with hexavalent 3x1D10v6-Fc. [0008] FIG.3 shows increased percentages of intracellular IFNγ⁺ CD4⁺ and intracellular IFNγ⁺ CD8⁺ T cells following co-stimulation of T cells from 4 healthy donors with hexavalent 3x1D10v6-Fc. [0009] FIG.4 shows that treatment with hexavalent 3x1D10v6-Fc inhibited Treg-mediated suppression of responder CD4⁺ T cell proliferation and increased the percentage of CD4⁺ T cells expressing the activation markers CD25 and CD71. [0010] FIG.5A-5C show that treatment with a broad range of concentrations of hexavalent 3x1D10v6-Fc (Hex-1D10v6) results in dose-dependent upregulation, plateau, and decrease in a dose-depending manner of CD4 and CD8 T cell proliferation (FIG.5A and 5B, respectively) and PD-L1 expression on the surface of CD4⁺ and CD8⁺ T-cells (FIG.5C). [0011] FIG.6A-6B show that the combination of pembrolizumab, an antibody targeting PD-1, and hexavalent 3x1D10v6-Fc (Hex-1D10v6) enhanced IL-2 production in a mixed lymphocyte reaction (MLR). FIG.6A shows the combination of 10 nM pembrolizumab with varying concentrations of hexavalent 3x1D10v6-Fc. FIG.6B shows the combination of 1 nM hexavalent 3x1D10v6-Fc with varying concentrations of pembrolizumab. [0012] FIG.7 shows that the combination of 10 nM pembrolizumab and a broad range concentrations of hexavalent 3x1D10v6-Fc (Hex-1D10v6) results in dose-dependent increase, plateau, and decrease in a dose-depending manner of IL-2 production in an MLR. [0013] FIG.8 shows the pharmacokinetic (PK) profile of 5 mg/kg, 20 mg/kg, or 60 mg/kg hexavalent 3x1D10v6-Fc (Hex-1D10v6) administered to cynomolgus monkeys. Systemic exposure was achieved and increased proportionally with the dose. [0014] FIG.9A-9B show the in vivo effect after systemic administration of varying doses of hexavalent 3x1D10v6-Fc on T-cell activation (FIG.9A) and proliferation (FIG.9B). [0015] FIG.10A-10B show in vivo target engagement of CD4 T cells from patients treated with hexavalent 3x1D10v6-Fc (Hex-1D10v6) and rebound over time. FIG.10A plots the % change in OX40 positive memory CD4 T cells on day 1 at the end of infusion. FIG.10B plots the total OX40 (%) on CD4 memory T cells day 1 pre-infusion (D1 Pre) and at the end of infusion (D1 EOI) over three treatment cycles (C1, C2, and C3). Attorney Docket No.01202-0062-00PCT DETAILED DESCRIPTION [0016] Embodiments provided herein relate to OX40 agonist combination therapy and methods of using OX40 agonist combination therapy. Embodiments provided herein also relate to their use in various methods of treating cancer. Definitions and Various Embodiments [0017] The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described. [0018] All references cited herein, including patent applications, patent publications, and Genbank Accession numbers are herein incorporated by reference, as if each individual reference were specifically and individually indicated to be incorporated by reference in its entirety. [0019] The techniques and procedures described or referenced herein are generally well understood and commonly employed using conventional methodology by those skilled in the art, such as, for example, the widely utilized methodologies described in Sambrook et al., Molecular Cloning: A Laboratory Manual 3rd. edition (2001) Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. CURRENT PROTOCOLS IN MOLECULAR BIOLOGY (F. M. Ausubel, et al. eds., (2003)); the series METHODS IN ENZYMOLOGY (Academic Press, Inc.): PCR 2: A PRACTICAL APPROACH (M. J. MacPherson, B. D. Hames and G. R. Taylor eds. (1995)), Harlow and Lane, eds. (1988) ANTIBODIES, A LABORATORY MANUAL, and ANIMAL CELL CULTURE (R. I. Freshney, ed. (1987)); Oligonucleotide Synthesis (M. J. Gait, ed., 1984); Methods in Molecular Biology, Humana Press; Cell Biology: A Laboratory Notebook (J. E. Cellis, ed., 1998) Academic Press; Animal Cell Culture (R. I. Freshney), ed., 1987); Introduction to Cell and Tissue Culture (J. P. Mather and P. E. Roberts, 1998) Plenum Press; Cell and Tissue Culture Laboratory Procedures (A. Doyle, J. B. Griffiths, and D. G. Newell, eds., 1993-8) J. Wiley and Sons; Handbook of Experimental Immunology (D. M. Weir and C. C. Blackwell, eds.); Gene Transfer Vectors for Mammalian Cells (J. M. Miller and M. P. Calos, eds., 1987); PCR: The Polymerase Chain Reaction, (Mullis et al., eds., 1994); Current Protocols in Immunology (J. E. Coligan et al., eds., 1991); Short Protocols in Molecular Biology (Wiley and Sons, 1999); Immunobiology (C. A. Janeway and P. Travers, 1997); Antibodies (P. Finch, 1997); Antibodies: A Practical Approach (D. Catty., ed., IRL Press, 1988-1989); Monoclonal Antibodies: A Practical Approach (P. Shepherd and C. Dean, eds., Oxford University Press, 2000); Using Antibodies: A Laboratory Manual (E. Harlow and D. Lane (Cold Spring Harbor Laboratory Press, 1999); The Antibodies (M. Zanetti and J. D. Capra, eds., Harwood Academic Attorney Docket No.01202-0062-00PCT Publishers, 1995); and Cancer: Principles and Practice of Oncology (V. T. DeVita et al., eds., J.B. Lippincott Company, 1993); and updated versions thereof. [0020] Unless otherwise defined, scientific and technical terms used in connection with the present disclosure shall have the meanings that are commonly understood by those of ordinary skill in the art. Further, unless otherwise required by context or expressly indicated, singular terms shall include pluralities and plural terms shall include the singular. For any conflict in definitions between various sources or references, the definition provided herein will control. [0021] It is understood that embodiments of the invention described herein include “consisting” and/or “consisting essentially of” embodiments. As used herein, the singular form “a”, “an”, and “the” includes plural references unless indicated otherwise. Use of the term “or” herein is not meant to imply that alternatives are mutually exclusive. [0022] In this application, the use of “or” means “and/or” unless expressly stated or understood by one skilled in the art. In the context of a multiple dependent claim, the use of “or” refers back to more than one preceding independent or dependent claim. [0023] The phrase “reference sample”, “reference cell”, or “reference tissue”, denote a sample with at least one known characteristic that can be used as a comparison to a sample with at least one unknown characteristic. In some embodiments, a reference sample can be used as a positive or negative indicator. A reference sample can be used to establish a level of protein and/or mRNA that is present in, for example, healthy tissue, in contrast to a level of protein and/or mRNA present in the sample with unknown characteristics. In some embodiments, the reference sample comes from the same subject, but is from a different part of the subject than that being tested. In some embodiments, the reference sample is from a tissue area surrounding or adjacent to the cancer. In some embodiments, the reference sample is not from the subject being tested, but is a sample from a subject known to have, or not to have, a disorder in question (for example, a particular cancer or OX40-related disorder). In some embodiments, the reference sample is from the same subject, but from a point in time before the subject developed cancer. In some embodiments, the reference sample is from a benign cancer sample, from the same or a different subject. When a negative reference sample is used for comparison, the level of expression or amount of the molecule in question in the negative reference sample will indicate a level at which one of skill in the art will appreciate, given the present disclosure, that there is no and/or a low level of the molecule. When a positive reference sample is used for comparison, the level of expression or amount of the molecule in question in the positive reference sample will indicate a level at which one of skill in the art will appreciate, given the present disclosure, that there is a level of the molecule. Attorney Docket No.01202-0062-00PCT [0024] The terms “benefit”, “clinical benefit”, “responsiveness”, and “therapeutic responsiveness” as used herein in the context of benefiting from or responding to administration of a therapeutic agent, can be measured by assessing various endpoints, e.g., inhibition, to some extent, of disease progression, including slowing down and complete arrest; reduction in the number of disease episodes and/or symptoms; reduction in lesion size; inhibition (that is, reduction, slowing down or complete stopping) of disease cell infiltration into adjacent peripheral organs and/or tissues; inhibition (that is, reduction, slowing down or complete stopping) of disease spread; relief, to some extent, of one or more symptoms associated with the disorder; increase in the length of disease-free presentation following treatment, for example, progression-free survival; increased overall survival; higher response rate; and/or decreased mortality at a given point of time following treatment. A subject or cancer that is “non- responsive” or “fails to respond” is one that has failed to meet the above noted qualifications to be “responsive”. [0025] The terms “nucleic acid molecule”, “nucleic acid” and “polynucleotide” may be used interchangeably, and refer to a polymer of nucleotides. Such polymers of nucleotides may contain natural and/or non-natural nucleotides, and include, but are not limited to, DNA, RNA, and PNA. “Nucleic acid sequence” refers to the linear sequence of nucleotides comprised in the nucleic acid molecule or polynucleotide. [0026] The terms “polypeptide” and “protein” are used interchangeably to refer to a polymer of amino acid residues, and are not limited to a minimum length. Such polymers of amino acid residues may contain natural or non-natural amino acid residues, and include, but are not limited to, peptides, oligopeptides, dimers, trimers, and multimers of amino acid residues. Both full- length proteins and fragments thereof are encompassed by the definition. The terms also include post-expression modifications of the polypeptide, for example, glycosylation, sialylation, acetylation, phosphorylation, and the like. Furthermore, for purposes of the present disclosure, a “polypeptide” refers to a protein which includes modifications, such as deletions, additions, and substitutions (generally conservative in nature), to the native sequence, as long as the protein maintains the desired activity. These modifications may be deliberate, as through site-directed mutagenesis, or may be accidental, such as through mutations of hosts which produce the proteins or errors due to PCR amplification. [0027] “OX40” as used herein refers to any native, mature OX40 that results from processing of an OX40 precursor in a cell. The term includes OX40 from any vertebrate source, including mammals such as primates (e.g., humans and cynomolgus or rhesus monkeys) and rodents (e.g., mice and rats), unless otherwise indicated. The term also includes naturally-occurring variants of OX40, such as splice variants or allelic variants. A nonlimiting exemplary human OX40 Attorney Docket No.01202-0062-00PCT amino acid sequence is shown, e.g., in GenBank Accession No. CAE11757.1. See SEQ ID NO. 1. A nonlimiting exemplary cynomolgus monkey OX40 amino acid sequence is shown, e.g., in NCBI Accession No. XP_005545179. See SEQ ID NO.2. [0028] “PD-1” as used herein refers to any native, mature PD-1 that results from processing of a PD-1 precursor in a cell. The term includes PD-1 from any vertebrate source, including mammals such as primates (e.g., humans and cynomolgus or rhesus monkeys) and rodents (e.g., mice and rats), unless otherwise indicated. The term also includes naturally-occurring variants of PD-1, such as splice variants or allelic variants. A nonlimiting exemplary human PD-1 amino acid sequence is shown, e.g., in UniProtKB/Swiss-Prot Accession No. Q15116. A nonlimiting exemplary cynomolgus monkey PD-1 amino acid sequence is shown, e.g., in GenBank Accession No. EF443145.1 [0029] "PD-L1” as used herein refers to any native, mature PD-L1 that results from processing of a PD-L1 precursor in a cell. The term includes PD-L1 from any vertebrate source, including mammals such as primates (e.g., humans and cynomolgus or rhesus monkeys) and rodents (e.g., mice and rats), unless otherwise indicated. The term also includes naturally-occurring variants of PD-L1, such as splice variants or allelic variants. A nonlimiting exemplary human PD-L1 amino acid sequence is shown, e.g., in UniProtKB/Swiss-Prot Accession No. Q9NZQ7.1. [0030] The term “specifically binds” to an antigen or epitope is a term that is well understood in the art, and methods to determine such specific binding are also well known in the art. A molecule is said to exhibit “specific binding” or “preferential binding” if it reacts or associates more frequently, more rapidly, with greater duration and/or with greater affinity with a particular cell or substance than it does with alternative cells or substances. A single-domain antibody (sdAb) or VHH-containing polypeptide “specifically binds” or “preferentially binds” to a target if it binds with greater affinity, avidity, more readily, and/or with greater duration than it binds to other substances. For example, a sdAb or VHH-containing polypeptide that specifically or preferentially binds to an OX40 epitope is a sdAb or VHH-containing polypeptide that binds this epitope with greater affinity, avidity, more readily, and/or with greater duration than it binds to other OX40 epitopes or non-OX40 epitopes. It is also understood by reading this definition that; for example, a sdAb or VHH-containing polypeptide that specifically or preferentially binds to a first target may or may not specifically or preferentially bind to a second target. As such, “specific binding” or “preferential binding” does not necessarily require (although it can include) exclusive binding. Generally, but not necessarily, reference to binding means preferential binding. “Specificity” refers to the ability of a binding protein to selectively bind an antigen. Attorney Docket No.01202-0062-00PCT [0031] As used herein, the term “modulate” with regard to the activity of OX40 refers to a change in the activity of OX40. In some embodiments, “modulate” refers to an increase in OX40 activity compared to OX40 in the absence of the modulator. [0032] As used herein, the term “epitope” refers to a site on a target molecule (for example, an antigen, such as a protein, nucleic acid, carbohydrate or lipid) to which an antigen-binding molecule (for example, a sdAb or VHH-containing polypeptide) binds. Epitopes often include a chemically active surface grouping of molecules such as amino acids, polypeptides or sugar side chains and have specific three-dimensional structural characteristics as well as specific charge characteristics. Epitopes can be formed both from contiguous and/or juxtaposed noncontiguous residues (for example, amino acids, nucleotides, sugars, lipid moiety) of the target molecule. Epitopes formed from contiguous residues (for example, amino acids, nucleotides, sugars, lipid moiety) typically are retained on exposure to denaturing solvents whereas epitopes formed by tertiary folding typically are lost on treatment with denaturing solvents. An epitope may include but is not limited to at least 3, at least 5 or 8-10 residues (for example, amino acids or nucleotides). In some embodiments, an epitope is less than 20 residues (for example, amino acids or nucleotides) in length, less than 15 residues or less than 12 residues. Two antibodies may bind the same epitope within an antigen if they exhibit competitive binding for the antigen. In some embodiments, an epitope can be identified by a certain minimal distance to a CDR residue on the antigen-binding molecule. In some embodiments, an epitope can be identified by the above distance, and further limited to those residues involved in a bond (for example, a hydrogen bond) between a residue of the antigen-binding molecule and an antigen residue. An epitope can be identified by various scans as well, for example an alanine or arginine scan can indicate one or more residues that the antigen-binding molecule can interact with. Unless explicitly denoted, a set of residues as an epitope does not exclude other residues from being part of the epitope for a particular antigen-binding molecule. Rather, the presence of such a set designates a minimal series (or set of species) of epitopes. Thus, in some embodiments, a set of residues identified as an epitope designates a minimal epitope of relevance for the antigen, rather than an exclusive list of residues for an epitope on an antigen. [0033] A “nonlinear epitope” or “conformational epitope” comprises noncontiguous polypeptides, amino acids and/or sugars within the antigenic protein to which an antigen-binding molecule specific to the epitope binds. In some embodiments, at least one of the residues will be noncontiguous with the other noted residues of the epitope; however, one or more of the residues can also be contiguous with the other residues. [0034] A “linear epitope” comprises contiguous polypeptides, amino acids and/or sugars within the antigenic protein to which an antigen-binding molecule specific to the epitope binds. It is Attorney Docket No.01202-0062-00PCT noted that, in some embodiments, not every one of the residues within the linear epitope need be directly bound (or involved in a bond) by the antigen-binding molecule. In some embodiments, linear epitopes can be from immunizations with a peptide that effectively consisted of the sequence of the linear epitope, or from structural sections of a protein that are relatively isolated from the remainder of the protein (such that the antigen-binding molecule can interact, at least primarily), just with that sequence section. [0035] The terms “antibody” and “antigen-binding molecule” are used interchangeably in the broadest sense and encompass various polypeptides that comprise antibody-like antigen-binding domains, including but not limited to conventional antibodies (typically comprising at least one heavy chain and at least one light chain), single-domain antibodies (sdAbs, comprising just one chain, which is typically similar to a heavy chain), VHH-containing polypeptides (polypeptides comprising at least one heavy chain only antibody variable domain, or VHH), and fragments of any of the foregoing so long as they exhibit the desired antigen-binding activity. In some embodiments, an antibody comprises a dimerization domain. Such dimerization domains include, but are not limited to, heavy chain constant domains (comprising CH1, hinge, CH2, and CH3, where CH1 typically pairs with a light chain constant domain, CL, while the hinge and/or CH3 mediates dimerization) and Fc domains (comprising hinge, CH2, and CH3, where the hinge and/or CH3 mediate dimerization). [0036] The term antibody also includes, but is not limited to, chimeric antibodies, humanized antibodies, and antibodies of various species such as camelid (including llama), shark, mouse, human, cynomolgus monkey, etc. [0037] The terms “single domain antibody” and “sdAb” are used interchangeably herein to refer to an antibody having a single, monomeric domain, such as a pair of variable domains of heavy chains (or VHH), without a light chain. [0038] The term “VHH” or “VHH domain” or “VHH antigen-binding domain” as used herein refers to the antigen-binding portion of a single-domain antibody, such as a camelid antibody or shark antibody. In some embodiments, a VHH comprises three CDRs and four framework regions, designated FR1, CDR1, FR2, CDR2, FR3, CDR3, and FR4. In some embodiments, a VHH may be truncated at the N-terminus or C-terminus such that it comprise only a partial FR1 and/or FR4, or lacks one or both of those framework regions, so long as the VHH substantially maintains antigen binding and specificity. [0039] The term “VHH-containing polypeptide” refers to a polypeptide that comprises at least one VHH domain. In some embodiments, a VHH polypeptide comprises two, three, or four or more VHH domains, wherein each VHH domain may be the same or different. In some embodiments, a VHH-containing polypeptide comprises an Fc domain. In some such Attorney Docket No.01202-0062-00PCT embodiments, the VHH polypeptide may form a dimer. Nonlimiting structures of VHH- containing polypeptides include VHH₁-Fc, VHH₁-VHH₂-Fc, and VHH₁-VHH₂-VHH₃-Fc, wherein VHH1, VHH2, and VHH3 may be the same or different. In some embodiments of such structures, one VHH may be connected to another VHH by a linker, or one VHH may be connected to the Fc by a linker. In some such embodiments, the linker comprises 1-20 amino acids, preferably 1-20 amino acids predominantly composed of glycine and, optionally, serine. In some embodiments, when a VHH-containing polypeptide comprises an Fc, it forms a dimer. Thus, the structure VHH₁-VHH₂-Fc, if it forms a dimer, is considered to be tetravalent (i.e., the dimer has four VHH domains). Similarly, the structure VHH₁-VHH₂-VHH₃-Fc, if it forms a dimer, is considered to be hexavalent (i.e., the dimer has six VHH domains). [0040] The term “monoclonal antibody” refers to an antibody (including an sdAb or VHH- containing polypeptide) of a substantially homogeneous population of antibodies, that is, the individual antibodies comprising the population are identical except for possible naturally- occurring mutations that may be present in minor amounts. Monoclonal antibodies are highly specific, being directed against a single antigenic site. Furthermore, in contrast to polyclonal antibody preparations, which typically include different antibodies directed against different determinants (epitopes), each monoclonal antibody is directed against a single determinant on the antigen. Thus, a sample of monoclonal antibodies can bind to the same epitope on the antigen. The modifier “monoclonal” indicates the character of the antibody as being obtained from a substantially homogeneous population of antibodies, and is not to be construed as requiring production of the antibody by any particular method. For example, the monoclonal antibodies may be made by the hybridoma method first described by Kohler and Milstein, 1975, Nature 256:495, or may be made by recombinant DNA methods such as described in U.S. Pat. No.4,816,567. The monoclonal antibodies may also be isolated from phage libraries generated using the techniques described in McCafferty et al., 1990, Nature 348:552-554, for example. [0041] The term “CDR” denotes a complementarity determining region as defined by at least one manner of identification to one of skill in the art. In some embodiments, CDRs can be defined in accordance with any of the Chothia numbering schemes, the Kabat numbering scheme, a combination of Kabat and Chothia, the AbM definition, the IMGT definition and/or the contact definition. A VHH comprises three CDRs, designated CDR1, CDR2, and CDR3. [0042] The term “heavy chain constant region” as used herein refers to a region comprising at least three heavy chain constant domains, C_H1, hinge, C_H2, and C_H3. Of course, non-function- altering deletions and alterations within the domains are encompassed within the scope of the term “heavy chain constant region,” unless designated otherwise. Nonlimiting exemplary heavy chain constant regions include γ, δ, and α. Nonlimiting exemplary heavy chain constant regions Attorney Docket No.01202-0062-00PCT also include ε and μ. Each heavy constant region corresponds to an antibody isotype. For example, an antibody comprising a γ constant region is an IgG antibody, an antibody comprising a δ constant region is an IgD antibody, and an antibody comprising an α constant region is an IgA antibody. Further, an antibody comprising a μ constant region is an IgM antibody, and an antibody comprising an ε constant region is an IgE antibody. Certain isotypes can be further subdivided into subclasses. For example, IgG antibodies include, but are not limited to, IgG1 (comprising a γ1 constant region), IgG2 (comprising a γ2 constant region), IgG3 (comprising a γ3 constant region), and IgG4 (comprising a γ₄ constant region) antibodies; IgA antibodies include, but are not limited to, IgA1 (comprising an α₁ constant region) and IgA2 (comprising an α₂ constant region) antibodies; and IgM antibodies include, but are not limited to, IgM1 and IgM2. [0043] In general, the numbering of the residues in the constant regions of an immunoglobulin heavy chain is that of the EU index as in Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991). The “EU index as in Kabat” refers to the residue numbering of the human IgG1 EU antibody. [0044] A “Fc region” as used herein refers to a portion of a heavy chain constant region comprising CH2 and CH3. In some embodiments, an Fc region comprises a hinge, CH2, and CH3. In various embodiments, when an Fc region comprises a hinge and/or a CH3, the hinge and/or CH3 mediates dimerization between two Fc-containing polypeptides. An Fc region may be of any antibody heavy chain constant region isotype discussed herein. In some embodiments, an Fc region is an IgG1, IgG2, IgG3, or IgG4. [0045] An “acceptor human framework” as used herein is a framework comprising the amino acid sequence of a heavy chain variable domain (V_H) framework derived from a human immunoglobulin framework or a human consensus framework, as discussed herein. An acceptor human framework derived from a human immunoglobulin framework or a human consensus framework can comprise the same amino acid sequence thereof, or it can contain amino acid sequence changes. In some embodiments, the number of amino acid changes are fewer than 10, or fewer than 9, or fewer than 8, or fewer than 7, or fewer than 6, or fewer than 5, or fewer than 4, or fewer than 3, across all of the human frameworks in a single antigen binding domain, such as a VHH. [0046] “Affinity” refers to the strength of the sum total of noncovalent interactions between a single binding site of a molecule (for example, an antibody or VHH-containing polypeptide) and its binding partner (for example, an antigen). The affinity or the apparent affinity of a molecule X for its partner Y can generally be represented by the dissociation constant (KD) or the KD-_apparent, respectively. Affinity can be measured by common methods known in the art (such as, for example, ELISA K_D, KinExA, flow cytometry, and/or surface plasmon resonance devices), Attorney Docket No.01202-0062-00PCT including those described herein. Such methods include, but are not limited to, methods involving BIAcore®, Octet®, or flow cytometry. [0047] The term “KD”, as used herein, refers to the equilibrium dissociation constant of an antigen-binding molecule/antigen interaction. When the term “KD” is used herein, it includes K_D and K_D-apparent. [0048] In some embodiments, the KD of the antigen-binding molecule is measured by flow cytometry using an antigen-expressing cell line and fitting the mean fluorescence measured at each antibody concentration to a non-linear one-site binding equation (Prism Software graphpad). In some such embodiments, the K_D is K_D-apparent. [0049] The term “biological activity” refers to any one or more biological properties of a molecule (whether present naturally as found in vivo, or provided or enabled by recombinant means). Biological properties include, but are not limited to, binding a ligand, inducing or increasing cell proliferation (such as T cell proliferation), and inducing or increasing expression of cytokines=. [0050] The term “OX40 activity” or “biological activity” of OX40, as used herein, includes any biological effect or at least one of the biologically relevant functions of the OX40 protein. In some embodiments, OX40 activity includes the ability of OX40 to interact or bind to OX40 ligand (OX40L). Nonlimiting exemplary OX40 activities include increasing NFκB signaling, increasing proliferation of CD4⁺ and/or CD8⁺ T cells, increasing IFNγ expression in T cells, increasing CD25 and/or CD71 expression on T cells, and reducing the suppressive activity of Treg cells on effector T cell activation and proliferation. [0051] An “agonist” or “activating” antibody (such as a sdAb or VHH-containing polypeptide) is one that increases and/or activates a biological activity of the target antigen. In some embodiments, the agonist antibody binds to an antigen and increases its biologically activity by at least about 20%, 40%, 60%, 80%, 85% or more. [0052] An “antagonist”, a “blocking” or “neutralizing” antibody is one that decreases and/or inactivates a biological activity of the target antigen. In some embodiments, the neutralizing antibody binds to an antigen and reduces its biologically activity by at least about 20%, 40%, 60%, 80%, 85% 90%, 95%, 99% or more. [0053] An “affinity matured” VHH-containing polypeptide refers to a VHH-containing polypeptide with one or more alterations in one or more CDRs compared to a parent VHH- containing polypeptide that does not possess such alterations, such alterations resulting in an improvement in the affinity of the VHH-containing polypeptide for antigen. [0054] A “humanized VHH” as used herein refers to a VHH in which one or more framework regions have been substantially replaced with human framework regions. In some instances, Attorney Docket No.01202-0062-00PCT certain framework region (FR) residues of the human immunoglobulin are replaced by corresponding non-human residues. Furthermore, the humanized VHH can comprise residues that are found neither in the original VHH nor in the human framework sequences, but are included to further refine and optimize VHH or VHH-containing polypeptide performance. In some embodiments, a humanized VHH-containing polypeptide comprises a human Fc region. As will be appreciated, a humanized sequence can be identified by its primary sequence and does not necessarily denote the process by which the antibody was created. [0055] A “functional Fc region” possesses an “effector function” of a native sequence Fc region. Exemplary “effector functions” include Fc receptor binding; Clq binding and complement dependent cytotoxicity (CDC); Fc receptor binding; antibody-dependent cell-mediated cytotoxicity (ADCC); phagocytosis; down regulation of cell surface receptors (for example B- cell receptor); and B-cell activation, etc. Such effector functions generally require the Fc region to be combined with a binding domain (for example, an antibody variable domain) and can be assessed using various assays. [0056] A “native sequence Fc region” comprises an amino acid sequence identical to the amino acid sequence of an Fc region found in nature. Native sequence human Fc regions include a native sequence human IgG1 Fc region (non-A and A allotypes); native sequence human IgG2 Fc region; native sequence human IgG3 Fc region; and native sequence human IgG4 Fc region as well as naturally occurring variants thereof. [0057] A “variant Fc region” comprises an amino acid sequence which differs from that of a native sequence Fc region by virtue of at least one amino acid modification. In some embodiments, a “variant Fc region” comprises an amino acid sequence which differs from that of a native sequence Fc region by virtue of at least one amino acid modification, yet retains at least one effector function of the native sequence Fc region. In some embodiments, the variant Fc region has at least one amino acid substitution compared to a native sequence Fc region or to the Fc region of a parent polypeptide, for example, from about one to about ten amino acid substitutions, and preferably, from about one to about five amino acid substitutions in a native sequence Fc region or in the Fc region of the parent polypeptide. In some embodiments, the variant Fc region herein will possess at least about 80% sequence identity with a native sequence Fc region and/or with an Fc region of a parent polypeptide, at least about 90% sequence identity therewith, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% sequence identity therewith. [0058] “Fc receptor” or “FcR” describes a receptor that binds to the Fc region of an antibody. In some embodiments, an FcγR is a native human FcR. In some embodiments, an FcR is one which binds an IgG antibody (a gamma receptor) and includes receptors of the FcγRI, FcγRII, and Attorney Docket No.01202-0062-00PCT FcγRIII subclasses, including allelic variants and alternatively spliced forms of those receptors. FcγRII receptors include FcγRIIA (an “activating receptor”) and FcγRIIB (an “inhibiting receptor”), which have similar amino acid sequences that differ primarily in the cytoplasmic domains thereof. Activating receptor FcγRIIA contains an immunoreceptor tyrosine-based activation motif (ITAM) in its cytoplasmic domain Inhibiting receptor FcγRIIB contains an immunoreceptor tyrosine-based inhibition motif (ITIM) in its cytoplasmic domain. (See, for example, Daeron, Annu. Rev. Immunol.15:203-234 (1997)). FcRs are reviewed, for example, in Ravetch and Kinet, Annu. Rev. Immunol 9:457-92 (1991); Capel et al., Immunomethods 4:25-34 (1994); and de Haas et al., J. Lab. Clin. Med.126:330-41 (1995). Other FcRs, including those to be identified in the future, are encompassed by the term “FcR” herein. For example, the term “Fc receptor” or “FcR” also includes the neonatal receptor, FcRn, which is responsible for the transfer of maternal IgGs to the fetus (Guyer et al., J. Immunol.117:587 (1976) and Kim et al., J. Immunol.24:249 (1994)) and regulation of homeostasis of immunoglobulins. Methods of measuring binding to FcRn are known (see, for example, Ghetie and Ward, Immunol. Today 18(12):592-598 (1997); Ghetie et al., Nature Biotechnology, 15(7):637-640 (1997); Hinton et al., J. Biol. Chem.279(8):6213-6216 (2004); WO 2004/92219 (Hinton et al.). [0059] The term “substantially similar” or “substantially the same,” as used herein, denotes a sufficiently high degree of similarity between two or more numeric values such that one of skill in the art would consider the difference between the two or more values to be of little or no biological and/or statistical significance within the context of the biological characteristic measured by said value. In some embodiments the two or more substantially similar values differ by no more than about any one of 5%, 10%, 15%, 20%, 25%, or 50%. [0060] A polypeptide “variant” means a biologically active polypeptide having at least about 80% amino acid sequence identity with the native sequence polypeptide after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity, and not considering any conservative substitutions as part of the sequence identity. Such variants include, for instance, polypeptides wherein one or more amino acid residues are added, or deleted, at the N- or C-terminus of the polypeptide. In some embodiments, a variant will have at least about 80% amino acid sequence identity. In some embodiments, a variant will have at least about 90% amino acid sequence identity. In some embodiments, a variant will have at least about 95% amino acid sequence identity with the native sequence polypeptide. [0061] As used herein, “percent (%) amino acid sequence identity” and “homology” with respect to a peptide, polypeptide or antibody sequence are defined as the percentage of amino acid residues in a candidate sequence that are identical with the amino acid residues in the specific peptide or polypeptide sequence, after aligning the sequences and introducing gaps, if Attorney Docket No.01202-0062-00PCT necessary, to achieve the maximum percent sequence identity, and not considering any conservative substitutions as part of the sequence identity. Alignment for purposes of determining percent amino acid sequence identity can be achieved in various ways that are within the skill in the art, for instance, using publicly available computer software such as BLAST, BLAST-2, ALIGN or MEGALIGNTM (DNASTAR) software. Those skilled in the art can determine appropriate parameters for measuring alignment, including any algorithms needed to achieve maximal alignment over the full length of the sequences being compared. [0062] An amino acid substitution may include but are not limited to the replacement of one amino acid in a polypeptide with another amino acid. Exemplary substitutions are shown in Table 1. Amino acid substitutions may be introduced into an antibody of interest and the products screened for a desired activity, for example, retained/improved antigen binding, decreased immunogenicity, or improved ADCC or CDC. Table 1

Attorney Docket No.01202-0062-00PCT

[0063] Amino acids may be grouped according to common side-chain properties: (1) hydrophobic: Norleucine, Met, Ala, Val, Leu, Ile; (2) neutral hydrophilic: Cys, Ser, Thr, Asn, Gln; (3) acidic: Asp, Glu; (4) basic: His, Lys, Arg; (5) residues that influence chain orientation: Gly, Pro; (6) aromatic: Trp, Tyr, Phe. [0064] Non-conservative substitutions will entail exchanging a member of one of these classes for another class. [0065] The term “vector” is used to describe a polynucleotide that can be engineered to contain a cloned polynucleotide or polynucleotides that can be propagated in a host cell. A vector can include one or more of the following elements: an origin of replication, one or more regulatory sequences (such as, for example, promoters and/or enhancers) that regulate the expression of the polypeptide of interest, and/or one or more selectable marker genes (such as, for example, antibiotic resistance genes and genes that can be used in colorimetric assays, for example, β- galactosidase). The term “expression vector” refers to a vector that is used to express a polypeptide of interest in a host cell. [0066] A “host cell” refers to a cell that may be or has been a recipient of a vector or isolated polynucleotide. Host cells may be prokaryotic cells or eukaryotic cells. Exemplary eukaryotic cells include mammalian cells, such as primate or non-primate animal cells; fungal cells, such as yeast; plant cells; and insect cells. Nonlimiting exemplary mammalian cells include, but are not limited to, NSO cells, PER.C6^® cells (Crucell), and 293 and CHO cells, and their derivatives, such as 293-6E, CHO-DG44, CHO-K1, CHO-S, and CHO-DS cells. Host cells include progeny of a single host cell, and the progeny may not necessarily be completely identical (in morphology or in genomic DNA complement) to the original parent cell due to natural, accidental, or deliberate mutation. Host cells also include primary cells, such as primary human immune cells. [0067] The term “isolated” as used herein refers to a molecule that has been separated from at least some of the components with which it is typically found in nature or produced. For Attorney Docket No.01202-0062-00PCT example, a polypeptide is referred to as “isolated” when it is separated from at least some of the components of the cell in which it was produced. Where a polypeptide is secreted by a cell after expression, physically separating the supernatant containing the polypeptide from the cell that produced it is considered to be “isolating” the polypeptide. Similarly, a polynucleotide is referred to as “isolated” when it is not part of the larger polynucleotide (such as, for example, genomic DNA or mitochondrial DNA, in the case of a DNA polynucleotide) in which it is typically found in nature, or is separated from at least some of the components of the cell in which it was produced, for example, in the case of an RNA polynucleotide. Thus, a DNA polynucleotide that is contained in a vector inside a host cell may be referred to as “isolated”. [0068] The terms “individual” and “subject” are used interchangeably herein to refer to an animal; for example a mammal. In some embodiments, methods of treating mammals, including, but not limited to, humans, rodents, simians, felines, canines, equines, bovines, porcines, ovines, caprines, mammalian laboratory animals, mammalian farm animals, mammalian sport animals, and mammalian pets, are provided. In some examples, an “individual” or “subject” refers to an individual or subject in need of treatment for a disease or disorder. In some embodiments, the subject to receive the treatment can be a patient, designating the fact that the subject has been identified as having a disorder of relevance to the treatment, or being at adequate risk of contracting the disorder. [0069] A “disease” or “disorder” as used herein refers to a condition where treatment is needed and/or desired. [0070] The term “tumor cell”, “cancer cell”, “cancer”, “tumor”, and/or “neoplasm”, unless otherwise designated, are used herein interchangeably and refer to a cell (or cells) exhibiting an uncontrolled growth and/or abnormal increased cell survival and/or inhibition of apoptosis which interferes with the normal functioning of bodily organs and systems. Included in this definition are benign and malignant cancers, polyps, hyperplasia, as well as dormant tumors or micrometastases. [0071] The terms “cancer” and “tumor” encompass solid and hematological/lymphatic cancers and also encompass malignant, pre-malignant, and benign growth, such as dysplasia. Also, included in this definition are cells having abnormal proliferation that is not impeded (e.g. immune evasion and immune escape mechanisms) by the immune system (e.g. virus infected cells). Exemplary cancers include, but are not limited to: basal cell carcinoma, biliary tract cancer; bladder cancer; bone cancer; brain and central nervous system cancer; breast cancer; cancer of the peritoneum; cervical cancer; choriocarcinoma; colon and rectum cancer; connective tissue cancer; cancer of the digestive system; endometrial cancer; esophageal cancer; eye cancer; cancer of the head and neck (e.g., head and neck squamous cell carcinoma Attorney Docket No.01202-0062-00PCT (HNSCC)); gastric cancer (e.g, gastric or gastroesophageal junction adenocarcinoma (G/GEA)), including gastrointestinal cancer; glioblastoma; hepatic carcinoma; hepatoma; intra-epithelial neoplasm; kidney or renal cancer (e.g., renal cell carcinoma); larynx cancer; leukemia; liver cancer; lung cancer (e.g., small-cell lung cancer, non-small cell lung cancer (NSCLC), adenocarcinoma of the lung, and squamous carcinoma of the lung); melanoma (e.g., cutaneous melanoma mucosal melanoma, and ocular/uveal melanoma); myeloma; neuroblastoma; oral cavity cancer (lip, tongue, mouth, and pharynx); ovarian cancer; pancreatic cancer; prostate cancer; retinoblastoma; rhabdomyosarcoma; rectal cancer; cancer of the respiratory system; salivary gland carcinoma; sarcoma; skin cancer; squamous cell cancer; stomach cancer; testicular cancer; thyroid cancer; uterine or endometrial cancer; cancer of the urinary system (e.g., urothelial (transitional) cell carcinoma (TCC)); vulval cancer; lymphoma including Hodgkin's and non-Hodgkin's lymphoma, as well as B-cell lymphoma (including low grade/follicular non-Hodgkin's lymphoma (NHL); small lymphocytic (SL) NHL; intermediate grade/follicular NHL; intermediate grade diffuse NHL; high grade immunoblastic NHL; high grade lymphoblastic NHL; high grade small non-cleaved cell NHL; bulky disease NHL; mantle cell lymphoma; AIDS-related lymphoma; and Waldenstrom's Macroglobulinemia; chronic lymphocytic leukemia (CLL); acute lymphoblastic leukemia (ALL); Hairy cell leukemia; chronic myeloblastic leukemia; as well as other carcinomas and sarcomas; and post-transplant lymphoproliferative disorder (PTLD), as well as abnormal vascular proliferation associated with phakomatoses, edema (such as that associated with brain tumors), and Meigs' syndrome. [0072] The term “non-tumor cell” as used herein refers to a normal cells or tissue. Exemplary non-tumor cells include, but are not limited to: T-cells, B-cells, natural killer (NK) cells, natural killer T (NKT) cells, dendritic cells, monocytes, macrophages, epithelial cells, fibroblasts, hepatocytes, interstitial kidney cells, fibroblast-like synoviocytes, osteoblasts, and cells located in the breast, skeletal muscle, pancreas, stomach, ovary, small intestines, placenta, uterus, testis, kidney, lung, heart, brain, liver, prostate, colon, lymphoid organs, bone, and bone-derived mesenchymal stem cells. The term “a cell or tissue located in the periphery” as used herein refers to non-tumor cells not located near tumor cells and/or within the tumor microenvironment. [0073] The term “cells or tissue within the tumor microenvironment” as used herein refers to the cells, molecules, extracellular matrix and/or blood vessels that surround and/or feed a tumor cell. Exemplary cells or tissue within the tumor microenvironment include, but are not limited to: tumor vasculature; tumor-infiltrating lymphocytes; fibroblast reticular cells; endothelial progenitor cells (EPC); cancer-associated fibroblasts; pericytes; other stromal cells; components of the extracellular matrix (ECM); dendritic cells; antigen presenting cells; T-cells; regulatory T- Attorney Docket No.01202-0062-00PCT cells (Treg cells); macrophages; neutrophils; myeloid-derived suppressor cells (MDSCs) and other immune cells located proximal to a tumor. Methods for identifying tumor cells, and/or cells/tissues located within the tumor microenvironment are well known in the art, as described herein, below. [0074] In some embodiments, an “increase” or “decrease” refers to a statistically significant increase or decrease, respectively. As will be clear to the skilled person, “modulating” can also involve effecting a change (which can either be an increase or a decrease) in affinity, avidity, specificity and/or selectivity of a target or antigen, for one or more of its ligands, binding partners, partners for association into a homomultimeric or heteromultimeric form, or substrates; effecting a change (which can either be an increase or a decrease) in the sensitivity of the target or antigen for one or more conditions in the medium or surroundings in which the target or antigen is present (such as pH, ion strength, the presence of co-factors, etc.); and/or cellular proliferation or cytokine production, compared to the same conditions but without the presence of a test agent. This can be determined in any suitable manner and/or using any suitable assay known per se or described herein, depending on the target involved. [0075] As used herein, “an immune response” is meant to encompass cellular and/or humoral immune responses that are sufficient to inhibit or prevent onset or ameliorate the symptoms of disease (for example, cancer or cancer metastasis). “An immune response” can encompass aspects of both the innate and adaptive immune systems. [0076] As used herein, “treatment” is an approach for obtaining beneficial or desired clinical results. “Treatment” as used herein, covers any administration or application of a therapeutic for disease in a mammal, including a human. For purposes of this disclosure, beneficial or desired clinical results include, but are not limited to, any one or more of: alleviation of one or more symptoms, diminishment of extent of disease, preventing or delaying spread (for example, metastasis, for example metastasis to the lung or to the lymph node) of disease, preventing or delaying recurrence of disease, delay or slowing of disease progression, amelioration of the disease state, inhibiting the disease or progression of the disease, inhibiting or slowing the disease or its progression, arresting its development, and remission (whether partial or total). Also encompassed by “treatment” is a reduction of pathological consequence of a proliferative disease. The methods provided herein contemplate any one or more of these aspects of treatment. In-line with the above, the term treatment does not require one-hundred percent removal of all aspects of the disorder. [0077] “Ameliorating” means a lessening or improvement of one or more symptoms as compared to not administering a therapeutic agent. “Ameliorating” also includes shortening or reduction in duration of a symptom. Attorney Docket No.01202-0062-00PCT [0078] The term “anti-cancer agent” is used herein in its broadest sense to refer to agents that are used in the treatment of one or more cancers. Exemplary classes of such agents in include, but are not limited to, chemotherapeutic agents, anti-cancer biologics (such as cytokines, receptor extracellular domain-Fc fusions, and antibodies), radiation therapy, CAR-T therapy, therapeutic oligonucleotides (such as antisense oligonucleotides and siRNAs) and oncolytic viruses. [0079] The term “biological sample” means a quantity of a substance from a living thing or formerly living thing. Such substances include, but are not limited to, blood, (for example, whole blood), plasma, serum, urine, amniotic fluid, synovial fluid, endothelial cells, leukocytes, monocytes, other cells, organs, tissues, bone marrow, lymph nodes and spleen. [0080] The term “checkpoint inhibitor” or “CPI” is used herein in its broadest sense to refer to agents that inhibit the activity of molecules involved in attenuating the immune response. Examples of immune checkpoint inhibitors include, but are not limited to, inhibitors of CTLA-4, PD-1, PD-L1, LAG-3, B7-H3, B7-H4, TIM3, A2AR, and IDO. [0081] The term “control” or “reference” refers to a composition known to not contain an analyte (“negative control”) or to contain an analyte (“positive control”). A positive control can comprise a known concentration of analyte. [0082] The terms “inhibition” or “inhibit” refer to a decrease or cessation of any phenotypic characteristic or to the decrease or cessation in the incidence, degree, or likelihood of that characteristic. To “reduce” or “inhibit” is to decrease, reduce or arrest an activity, function, and/or amount as compared to a reference. In some embodiments, by “reduce” or “inhibit” is meant the ability to cause an overall decrease of 10% or greater. In some embodiments, by “reduce” or “inhibit” is meant the ability to cause an overall decrease of 50% or greater. In some embodiments, by “reduce” or “inhibit” is meant the ability to cause an overall decrease of 75%, 85%, 90%, 95%, or greater. In some embodiments, the amount noted above is inhibited or decreased over a period of time, relative to a control over the same period of time. [0083] As used herein, “delaying development of a disease” means to defer, hinder, slow, retard, stabilize, suppress and/or postpone development of the disease (such as cancer). This delay can be of varying lengths of time, depending on the history of the disease and/or individual being treated. As is evident to one skilled in the art, a sufficient or significant delay can, in effect, encompass prevention, in that the individual does not develop the disease. For example, a late stage cancer, such as development of metastasis, may be delayed. [0084] “Preventing,” as used herein, includes providing prophylaxis with respect to the occurrence or recurrence of a disease in a subject that may be predisposed to the disease but has not yet been diagnosed with the disease. Unless otherwise specified, the terms “reduce”, Attorney Docket No.01202-0062-00PCT “inhibit”, or “prevent” do not denote or require complete prevention over all time, but just over the time period being measured. [0085] A “therapeutically effective amount” of a substance/molecule, agonist or antagonist may vary according to factors such as the disease state, age, sex, and weight of the individual, and the ability of the substance/molecule, agonist or antagonist to elicit a desired response in the individual. A therapeutically effective amount is also one in which any toxic or detrimental effects of the substance/molecule, agonist or antagonist are outweighed by the therapeutically beneficial effects. A therapeutically effective amount may be delivered in one or more administrations. A therapeutically effective amount refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired therapeutic and/or prophylactic result. [0086] The terms “pharmaceutical formulation” and “pharmaceutical composition” refer to a preparation which is in such form as to permit the biological activity of the active ingredient(s) to be effective, and which contains no additional components which are unacceptably toxic to a subject to which the formulation would be administered. Such formulations may be sterile. [0087] A “pharmaceutically acceptable carrier” refers to a non-toxic solid, semisolid, or liquid filler, diluent, encapsulating material, formulation auxiliary, or carrier conventional in the art for use with a therapeutic agent that together comprise a “pharmaceutical composition” for administration to a subject. A pharmaceutically acceptable carrier is non-toxic to recipients at the dosages and concentrations employed and are compatible with other ingredients of the formulation. The pharmaceutically acceptable carrier is appropriate for the formulation employed. [0088] The term “in combination” refers to the use of more than one therapeutic agent as part of a therapeutic regimen. The use of the term “in combination” does not restrict the order in which individual therapeutic agents are to be administered to a subject with a disease or disorder (e.g., a human patient or other mammal), nor does it mean that the agents are administered or must be administered at exactly the same time, but rather it is meant that such agents are administered to the subject concurrently, or in a sequence within a time interval, such that such agents provide an increased benefit relative to the benefit provided if such agents were administered otherwise. For example, a therapeutic agent may be administered at the same time or sequentially in any order at different points in time; however, if not administered at the same time, they should be administered within an appropriate time period so as to provide the desired therapeutic or prophylactic effect. Each administered agent can be administered separately, in any appropriate form, and by any suitable route, e.g., one by the oral route and one parenterally, etc. Particular dosing regimens for administering the therapeutic agents of the present invention to a subject in need thereof are provided herein. Attorney Docket No.01202-0062-00PCT [0089] The term “concurrently” is used herein to refer to administration of two or more therapeutic agents, where at least part of the administration overlaps in time, or where the administration of one therapeutic agent falls within a short period of time relative to administration of the other therapeutic agent, or wherein the therapeutic effect of both agents overlap for at least a period of time. [0090] The term “sequentially” is used herein to refer to administration of two or more therapeutic agents that does not overlap in time, or wherein the therapeutic effects of the agents do not overlap. [0091] As used herein, “in conjunction with” refers to administration of one treatment modality in addition to another treatment modality. As such, “in conjunction with” refers to administration of one treatment modality before, during, or after administration of the other treatment modality to the individual. [0092] The term “package insert” is used to refer to instructions customarily included in commercial packages of therapeutic products, that contain information about the indications, usage, dosage, administration, combination therapy, contraindications and/or warnings concerning the use of such therapeutic products. [0093] An “article of manufacture” is any manufacture (for example, a package or container) or kit comprising at least one reagent, for example, a medicament for treatment of a disease or disorder (for example, cancer), or a probe for specifically detecting a biomarker described herein. In some embodiments, the manufacture or kit is promoted, distributed, or sold as a unit for performing the methods described herein. [0094] The terms “label” and “detectable label” mean a moiety attached, for example, to an antibody or antigen to render a reaction (for example, binding) between the members of the specific binding pair, detectable. The labeled member of the specific binding pair is referred to as “detectably labeled.” Thus, the term “labeled binding protein” refers to a protein with a label incorporated that provides for the identification of the binding protein. In some embodiments, the label is a detectable marker that can produce a signal that is detectable by visual or instrumental means, for example, incorporation of a radiolabeled amino acid or attachment to a polypeptide of biotinyl moieties that can be detected by marked avidin (for example, streptavidin containing a fluorescent marker or enzymatic activity that can be detected by optical or colorimetric methods). Examples of labels for polypeptides include, but are not limited to, the following: radioisotopes or radionuclides (for example,³H,¹⁴C,³⁵S,⁹⁰Y,⁹⁹Tc,¹¹¹In,¹²⁵I,¹³¹I,¹⁷⁷Lu,¹⁶⁶Ho, or¹⁵³Sm); chromogens, fluorescent labels (for example, FITC, rhodamine, lanthanide phosphors), enzymatic labels (for example, horseradish peroxidase, luciferase, alkaline phosphatase); chemiluminescent markers; biotinyl groups; predetermined polypeptide Attorney Docket No.01202-0062-00PCT epitopes recognized by a secondary reporter (for example, leucine zipper pair sequences, binding sites for secondary antibodies, metal binding domains, epitope tags); and magnetic agents, such as gadolinium chelates. Representative examples of labels commonly employed for immunoassays include moieties that produce light, for example, acridinium compounds, and moieties that produce fluorescence, for example, fluorescein. In this regard, the moiety itself may not be detectably labeled but may become detectable upon reaction with yet another moiety. Exemplary OX40 Agonists [0095] OX40 agonists are provided herein. In various embodiments, the OX40 agonists are OX40-binding polypeptides that comprise at least one VHH domain that binds OX40. In some embodiments, an agonist OX40-binding polypeptide provided herein comprises one, two, three, four, five, six, seven, or eight VHH domains that bind OX40. In some embodiments, an agonist OX40-binding polypeptide provided herein comprises one, two, three, or four VHH domains that bind OX40. In some embodiments, the OX40 agonist is a hexavalent OX40-binding polypeptide (such as INBRX-106). [0096] In some embodiments, an OX40 agonist comprises at least one VHH domain that binds OX40 and an Fc domain. In some embodiments, an OX40 agonist provided herein comprises one, two, three, or four VHH domains that bind OX40 and an Fc domain. In some embodiments, an OX40 agonist comprising an Fc domain is a homodimer under physiological conditions. In some embodiments, an Fc domain mediates dimerization at physiological conditions such that a dimer is formed that doubles the number of OX40 binding sites. For example, an agonist OX40-binding polypeptide comprising three VHH domains that bind OX40 and an Fc region is trivalent as a monomer, but at physiological conditions, the Fc region may mediate dimerization, such that the OX40 agonist comprising such polypeptide exists as a hexavalent dimer under such conditions. Nonlimiting exemplary OX40 agonists include hexavalent 3x1D10v6-Fc, which is also referred to as Hex-1D10v6, INBRX106, and INBRX- 106. Without intending to be bound by any particular theory, it is thought that co-stimulation through OX40 is improved by clustering OX40, meaning that multivalent OX40 agonists (such as hexavalent) are more effective than monovalent or bivalent OX40 agonists. [0097] In various embodiments, a VHH domain that binds OX40 comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 2, a CDR2 comprising the amino acid sequence of SEQ ID NO: 3, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 4. In some embodiments, the VHH domain is humanized. [0098] In some embodiments, a VHH domain that binds OX40 may be humanized. Humanized antibodies (such as VHH-containing polypeptides) are useful as therapeutic molecules because Attorney Docket No.01202-0062-00PCT humanized antibodies reduce or eliminate the human immune response to non-human antibodies, which can result in an immune response to an antibody therapeutic, and decreased effectiveness of the therapeutic. Generally, a humanized antibody comprises one or more variable domains in which CDRs, (or portions thereof) are derived from a non-human antibody, and FRs (or portions thereof) are derived from human antibody sequences. A humanized antibody optionally will also comprise at least a portion of a human constant region. In some embodiments, some FR residues in a humanized antibody are substituted with corresponding residues from a non-human antibody (for example, the antibody from which the CDR residues are derived), for example, to restore or improve antibody specificity or affinity. [0099] Humanized antibodies and methods of making them are reviewed, for example, in Almagro and Fransson, (2008) Front. Biosci.13: 1619-1633, and are further described, for example, in Riechmann et al., (1988) Nature 332:323-329; Queen et al., (1989) Proc. Natl Acad. Sci. USA 86: 10029-10033; US Patent Nos.5, 821,337, 7,527,791, 6,982,321, and 7,087,409; Kashmiri et al., (2005) Methods 36:25-34; Padlan, (1991) Mol. Immunol.28:489-498 (describing “resurfacing”); Dall'Acqua et al., (2005) Methods 36:43-60 (describing “FR shuffling”); and Osbourn et al., (2005) Methods 36:61-68 and Klimka et al., (2000) Br. J. Cancer, 83:252-260 (describing the “guided selection” approach to FR shuffling). [00100] Human framework regions that can be used for humanization include but are not limited to: framework regions selected using the “best-fit” method (see, for example, Sims et al. (1993) J. Immunol.151 :2296); framework regions derived from the consensus sequence of human antibodies of a particular subgroup of heavy chain variable regions (see, for example, Carter et al. (1992) Proc. Natl. Acad. Sci. USA, 89:4285; and Presta et al. (1993) J. Immunol, 151:2623); human mature (somatically mutated) framework regions or human germline framework regions (see, for example, Almagro and Fransson, (2008) Front. Biosci.13:1619- 1633); and framework regions derived from screening FR libraries (see, for example, Baca et al., (1997) J. Biol. Chem.272: 10678-10684 and Rosok et al., (1996) J. Biol. Chem.271 :22611- 22618). Typically, the FR regions of a VHH are replaced with human FR regions to make a humanized VHH. In some embodiments, certain FR residues of the human FR are replaced in order to improve one or more properties of the humanized VHH. VHH domains with such replaced residues are still referred to herein as “humanized.” [00101] In some embodiments, a VHH domain that binds OX40 comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 2, a CDR2 comprising the amino acid sequence of SEQ ID NO: 3, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 4. In some embodiments, an OX40 agonist comprises at least one VHH domain comprising the Attorney Docket No.01202-0062-00PCT amino acid sequence of SEQ ID NO: 1. In some embodiments, an OX40 agonist comprises one, two, three, or four VHH domains comprising the amino acid sequence of SEQ ID NO: 1. [00102] In some embodiments, an OX40 agonist comprises three VHH domains that bind OX40 and an Fc domain. In some such embodiments, each VHH domain comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 2, a CDR2 comprising the amino acid sequence of SEQ ID NO: 3, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 4. In some embodiments, each VHH domain comprises the amino acid sequence of SEQ ID NO: 1. In some embodiments, an OX40 agonist that comprises three VHH domains comprises the amino acid sequence of SEQ ID NO: 9. [00103] In various embodiments, an Fc domain included in an OX40-bindng polypeptide, such as an agonist OX40-binding polypeptide, is a human Fc domain, or is derived from a human Fc domain. [00104] In some embodiments, an Fc domain included in an OX40-bindng polypeptide, such as an agonist OX40-binding polypeptide, is derived from a human Fc domain, and comprises a three amino acid deletion in the lower hinge corresponding to IgG1 E233, L234, and L235, herein referred to as “Fc xELL.” Fc xELL polypeptides do not engage FcγRs and thus are referred to as “effector silent” or “effector null”, however in some embodiments, xELL Fc domains bind FcRn and therefore have extended half-life and transcytosis associated with FcRn mediated recycling. Nonlimiting exemplary Fc xELL domains comprise the amino acid sequence of SEQ ID NO: 14 or 15. [00105] In some embodiments, the Fc domain included in an OX40-bindng polypeptide, such as an agonist OX40-binding polypeptide, is derived from a human Fc domain and comprises mutations M252Y and M428V, herein referred to as “Fc-YV”. In some embodiments, such mutations enhance binding to FcRn at the acidic pH of the endosome (near 6.5), while losing detectable binding at neutral pH (about 7.2), allowing for enhanced FcRn mediated recycling and extended half-life. [00106] Nonlimiting exemplary Fc domains that may be used in an OX40-bindng polypeptide, such as an agonist OX40-binding polypeptide, include Fc domains comprising the amino acid sequences of SEQ ID NOs: 12-15. [00107] In some embodiments, an OX40 agonist that comprises three VHH domains and an Fc domain comprises the amino acid sequence of SEQ ID NO: 9 and an Fc domain fused to the C-terminus of that amino acid sequence. In some domains, an OX40 agonist that comprises three VHH domains and an Fc domain comprises the amino acid sequence of SEQ ID NO: 9 fused to the N-terminus of the amino acid sequence of SEQ ID NO: 12 or 13. In some embodiments, an OX40 agonist that comprises three VHH domains and an Fc domain comprise Attorney Docket No.01202-0062-00PCT the amino acid sequence of SEQ ID NO: 10 or 11. In some embodiments, the OX40 agonist comprises two polypeptides each having the amino acid sequence of SEQ ID NO: 10 or 11. In some embodiments, the OX40 agonist is INBRX-106. Exemplary activities of OX40 agonists [00108] In various embodiments, the OX40 agonists provided herein are agonists of OX40 activity. Agonist activity may be determined, in some embodiments, using the methods provided in the Examples herein, such as using Jurkat/OX40 reporter cells or similar cells. [00109] In some embodiments, the OX40 agonists provided herein increase proliferation of CD4⁺ and/or CD8⁺ T cells in vitro and/ or in vivo. In some embodiments, an OX40 agonist provided herein increases CD4⁺ and/or CD8⁺ T cells proliferation in vitro. In some embodiments, the OX40 agonist increases CD4⁺ and/or CD8⁺ T cells proliferation by at least 1.5-fold or at least 2-fold. The increase in proliferation of CD4⁺ and/or CD8⁺ T cells may be determined by any method in the art, such as for example, the methods provided in the Examples herein. A nonlimiting exemplary assay is as follows. CD4⁺ and/or CD8⁺ T cells may be isolated from one or more healthy human donors and stained with CellTrace Violet (CTV). The T cells are then co-stimulated with anti-CD3 antibody and an OX40-bindng polypeptide, and then analyzed by FACS. Loss of CTV staining indicates proliferation. In some embodiments, an increase in CD4⁺ and/or CD8⁺ T cell proliferation is determined as an average from a set of experiments or from pooled T cells, such as by measuring proliferation of CD4⁺ and/or CD8⁺ T cells isolated from different healthy human donors. In some embodiments, an increase in CD4⁺ and/or CD8⁺ T cell proliferation is determined as an average from experiments carried out using T cells from at least five or at least ten different healthy donors, or from a pool of T cells from at least five or at least ten different healthy donors. In some embodiments, the OX40 agonists provided herein increase proliferation of CD4⁺ and/or CD8⁺ T cells even in the presence of Treg cells. [00110] In some embodiments, the OX40 agonists provided herein increase CD25 expression on CD4⁺ and/or CD8⁺ T cells in vitro and/ or in vivo. CD25 expression indicates T cell activation. In some embodiments, an OX40 agonist provided herein increases CD25 expression on CD4⁺ and/or CD8⁺ T cells in vitro. In some embodiments, the OX40 agonist increases CD25 expression on CD4⁺ and/or CD8⁺ T cells by at least 1.5-fold or at least 2-fold. The increase in CD25 expression on CD4⁺ and/or CD8⁺ T cells may be determined by any method in the art, such as for example, the methods provided in the Examples herein. A nonlimiting exemplary assay is as follows. CD4⁺ and/or CD8⁺ T cells may be isolated from one or more healthy human donors and co-stimulated with anti-CD3 antibody and an OX40-bindng polypeptide, and then analyzed by FACS for CD25 expression. In some embodiments, an Attorney Docket No.01202-0062-00PCT increase in CD25 expression on CD4⁺ and/or CD8⁺ T cell proliferation is determined as an average from a set of experiments or from pooled T cells, such as by measuring CD25 expression on CD4⁺ and/or CD8⁺ T cells isolated from different healthy human donors. In some embodiments, an increase in CD25 expression on CD4⁺ and/or CD8⁺ T cells is determined as an average from experiments carried out using T cells from at least five or at least ten different healthy donors, or from a pool of T cells from at least five or at least ten different healthy donors. In some embodiments, the OX40 agonists provided herein increase CD25 expression on CD4⁺ and/or CD8⁺ T cells even in the presence of Treg cells. [00111] In some embodiments, the OX40 agonists provided herein increase CD71 expression on CD4⁺ and/or CD8⁺ T cells in vitro and/ or in vivo. CD71 expression indicates T cell activation. In some embodiments, an OX40 agonist provided herein increases CD71 expression on CD4⁺ and/or CD8⁺ T cells in vitro. In some embodiments, the OX40 agonist increases CD71 expression on CD4⁺ and/or CD8⁺ T cells by at least 1.5-fold or at least 2-fold. The increase in CD71 expression on CD4⁺ and/or CD8⁺ T cells may be determined by any method in the art, such as for example, the methods provided in the Examples herein. A nonlimiting exemplary assay is as follows. CD4⁺ and/or CD8⁺ T cells may be isolated from one or more healthy human donors and co-stimulated with anti-CD3 antibody and an OX40-bindng polypeptide, and then analyzed by FACS for CD71 expression. In some embodiments, an increase in CD71 expression on CD4⁺ and/or CD8⁺ T cell proliferation is determined as an average from a set of experiments or from pooled T cells, such as by measuring CD71 expression on CD4⁺ and/or CD8⁺ T cells isolated from different healthy human donors. In some embodiments, an increase in CD71 expression on CD4⁺ and/or CD8⁺ T cells is determined as an average from experiments carried out using T cells from at least five or at least ten different healthy donors, or from a pool of T cells from at least five or at least ten different healthy donors. In some embodiments, the OX40 agonists provided herein increase CD71 expression on CD4⁺ and/or CD8⁺ T cells even in the presence of Treg cells. [00112] In some embodiments, the OX40 agonists provided herein increase PD-L1 expression on CD4⁺ and/or CD8⁺ T cells in vitro and/ or in vivo. In some embodiments, an OX40 agonist provided herein increases PD-L1 expression in CD4⁺ and/or CD8⁺ T cells in vitro. In some embodiments, the OX40 agonist increases PD-L1 expression on CD4⁺ and/or CD8⁺ T cells by at least 1.5-fold, at least 2-fold, at least 3-fold, or by at least 5-fold. The increase in PD- L1 expression in CD4⁺ and/or CD8⁺ T cells may be determined by any method in the art, such as for example, the methods provided in the Examples herein. A nonlimiting exemplary assay is as follows. CD4⁺ and/or CD8⁺ T cells are isolated from one or more healthy human donors and co- Attorney Docket No.01202-0062-00PCT stimulated with anti-CD3 antibody and an OX40-bindng polypeptide. The cells are then analyzed by FACS for PD-L1 expression. [00113] In some embodiments, the OX40 agonists provided herein increase IFNγ expression in CD4⁺ and/or CD8⁺ T cells in vitro and/ or in vivo. IFNγ expression indicates T cell activation. In some embodiments, an OX40 agonist provided herein increases IFNγ expression in CD4⁺ and/or CD8⁺ T cells in vitro. In some embodiments, the OX40 agonist increases IFNγ expression on CD4⁺ and/or CD8⁺ T cells by at least 1.5-fold, at least 2-fold, at least 3-fold, or by at least 5-fold. The increase in IFNγ expression in CD4⁺ and/or CD8⁺ T cells may be determined by any method in the art, such as for example, the methods provided in the Examples herein. A nonlimiting exemplary assay is as follows. CD4⁺ and/or CD8⁺ T cells may be isolated from one or more healthy human donors and co-stimulated with anti-CD3 antibody and an OX40-bindng polypeptide. To determine intracellular IFNγ expression, cells are pelleted and surface-labeled with detectable anti-CD4 and anti-CD8 antibodies. Cells are then fixed and permeablized, and then stained with detectable anti-IFNγ antibody. IFNγ⁺CD4⁺ or IFNγ⁺CD8⁺ cells are then detected by FACS. In some embodiments, an increase in IFNγ expression on CD4⁺ and/or CD8⁺ T cell proliferation is determined as an average from a set of experiments or from pooled T cells, such as by measuring IFNγ expression in CD4⁺ and/or CD8⁺ T cells isolated from different healthy human donors. In some embodiments, an increase in IFNγ expression in CD4⁺ and/or CD8⁺ T cells is determined as an average from experiments carried out using T cells from at least five or at least ten different healthy donors, or from a pool of T cells from at least five or at least ten different healthy donors. In some embodiments, the OX40 agonists provided herein increase IFNγ expression in CD4⁺ and/or CD8⁺ T cells even in the presence of Treg cells. [00114] In some embodiments, the OX40 agonists provided herein reduce or attenuate suppressive activity of regulatory T-cells (Tregs). In some embodiments, the OX40 agonists reduce Treg suppressive activity on CD4⁺ and/or CD8⁺ T cells by at least 10%, at least 20%, at least 30%, or by at least 50%. The decrease in Treg suppressive activity on conventional CD4⁺ and/or CD8⁺ T cells may be determined by any method in the art, such as for example, the methods provided in the Examples herein. A nonlimiting exemplary assay is as follows. Tregs and CD4⁺ T-cells are differentially labeled with fluorescent proliferative cellular dyes following isolation from healthy human donor PBMCs. CD4⁺ T-cells are stimulated with anti-CD3 antibody, while Treg cells are incubated in the presence of an OX40 agonists provided herein. The two T-cell populations are co-cultured for 3 days and proliferation and activation of CD4⁺ T-cells is monitored by flow cytometry. In some embodiments, the OX40 agonists provided herein increases CD4⁺ and/or CD8⁺ T-cell activation and proliferation in the presence of Treg Attorney Docket No.01202-0062-00PCT cells, for example, compared to CD4⁺ and/or CD8⁺ T-cell activation and proliferation in the presence of Treg cells but the absence of an OX40 agonist provided herein. [0134] In some embodiments, the OX40 agonist is multivalent, comprising more than one OX40 binding domain. In various embodiments, the OX40 agonist comprises two, three, four, five, six, seven, or eight OX40 binding domains. In some such embodiments, at least one, or all of the OX40 binding domains are the same. In some such embodiments, all of the OX40 binding domains comprise CDR1, CDR2, and CDR3 of 1D10v6 (SEQ ID NOs: 2, 3, and 4, respectively). In some embodiments, at least one, or all of the OX40 binding domains comprise the 1D10v6 VHH (SEQ ID NO: 1). [0135] Provided herein are engineered cells that express an OX40 agonist provided herein. In some embodiments, the OX40 agonist is secreted from the cell. In some embodiments, the OX40 agonist comprises a signal peptide, e.g., an antibody signal peptide or other signal sequence that causes the polypeptide to be secreted by a cell. The signal peptide, or a portion of the signal peptide, may be cleaved from the polypeptide when it is secreted. In some embodiments, an OX40 agonist may be encoded by a nucleic acid in a cell, and then expressed and secreted by the cell. The nucleic acid typically contains suitable regulatory sequences (such as, for example, promoters and/or enhancers) for expression under desired conditions. The nucleic acid may be incorporated into the genome of the cell, or may be present as extra- genomic nucleic acid. In some embodiments, the cell is an immune cell, such as, for example, a primary immune cell. [0136] Also provided herein are methods for the prevention and/or treatment of a disease or condition in a subject, such as a cancer, that includes administering to a subject engineered cells provided herein. Generally, the subject is in need of treatment for the disease or condition. pharmaceutically active amount of a cell and/or of a pharmaceutical composition of the invention. In some embodiments, cells that express and secrete an OX40 binding polypeptide provided herein are used in treatment. OX40 Agonist Expression and Production [00149] Nucleic acid molecules comprising polynucleotides that encode an OX40 agonist are provided. Thus, in various embodiments, nucleic acid molecules are provided that encode a VHH domain that binds OX40, comprising a CDR1 comprising the amino acid sequence of SEQ ID NO: 2, a CDR2 comprising the amino acid sequence of SEQ ID NO: 3, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 4. In some embodiments, nucleic acid molecules are provided that encode an OX40 agonist that comprises at least one, such as one, two, three, or four VHH domain comprising the amino acid sequence of SEQ ID NO: 1. In Attorney Docket No.01202-0062-00PCT various embodiments, the nucleic acid molecule further encodes an Fc domain, such as an Fc domain of any one of SEQ ID NOs: 12-15. [00150] In some embodiments, a nucleic acid molecule is provided that encodes an OX40 agonist that comprises three VHH domains and an Fc domain comprise the amino acid sequence of SEQ ID NO: 9 and an Fc domain fused to the C-terminus of that amino acid sequence. In some domains, an OX40 agonist that comprises three VHH domains and an Fc domain comprises the amino acid sequence of SEQ ID NO: 9 fused to the N-terminus of the amino acid sequence of SEQ ID NO: 12 or 13. In some embodiments, a nucleic acid molecule is provided that encodes an OX40 agonist comprising the amino acid sequence of SEQ ID NO: 10 or 11. In any of the foregoing embodiments, the nucleic acid molecule may also encode a leader sequence that directs secretion of the OX40 agonist, which leader sequence is typically cleaved such that it is not present in the secreted polypeptide. The leader sequence may be a native heavy chain (or VHH) leader sequence, or may be another heterologous leader sequence. [00151] Nucleic acid molecules can be constructed using recombinant DNA techniques conventional in the art. In some embodiments, a nucleic acid molecule is an expression vector that is suitable for expression in a selected host cell. [00152] Vectors comprising nucleic acids that encode the OX40 agonists described herein are provided. Such vectors include, but are not limited to, DNA vectors, phage vectors, viral vectors, retroviral vectors, etc. In some embodiments, a vector is selected that is optimized for expression of polypeptides in a desired cell type, such as CHO or CHO-derived cells, or in NSO cells. Exemplary such vectors are described, for example, in Running Deer et al., Biotechnol. Prog.20:880-889 (2004). [00153] In some embodiments, an OX40 agonist may be expressed in prokaryotic cells, such as bacterial cells; or in eukaryotic cells, such as fungal cells (such as yeast), plant cells, insect cells, and mammalian cells. Such expression may be carried out, for example, according to procedures known in the art. Exemplary eukaryotic cells that may be used to express polypeptides include, but are not limited to, COS cells, including COS 7 cells; 293 cells, including 293-6E cells; CHO cells, including CHO-S, DG44. Lec13 CHO cells, and FUT8 CHO cells; PER.C6^® cells (Crucell); and NSO cells. In some embodiments, the OX40 agonists may be expressed in yeast. See, e.g., U.S. Publication No. US 2006/0270045 A1. In some embodiments, a particular eukaryotic host cell is selected based on its ability to make desired post-translational modifications to the polypeptide. For example, in some embodiments, CHO cells produce polypeptides that have a higher level of sialylation than the same polypeptide produced in 293 cells. Attorney Docket No.01202-0062-00PCT [00154] Introduction of one or more nucleic acids (such as vectors) into a desired host cell may be accomplished by any method, including but not limited to, calcium phosphate transfection, DEAE-dextran mediated transfection, cationic lipid-mediated transfection, electroporation, transduction, infection, etc. Nonlimiting exemplary methods are described, for example, in Sambrook et al., Molecular Cloning, A Laboratory Manual, 3^rd ed. Cold Spring Harbor Laboratory Press (2001). Nucleic acids may be transiently or stably transfected in the desired host cells, according to any suitable method. [00155] Host cells comprising any of the nucleic acids or vectors described herein are also provided. In some embodiments, a host cell that expresses an OX40 agonist described herein is provided. The OX40 agonists expressed in host cells can be purified by any suitable method. Such methods include, but are not limited to, the use of affinity matrices or hydrophobic interaction chromatography. Suitable affinity ligands include the ROR1 ECD and agents that bind Fc regions. For example, a Protein A, Protein G, Protein A/G, or an antibody affinity column may be used to bind the Fc region and to purify an OX40 agonist that comprises an Fc region. Hydrophobic interactive chromatography, for example, a butyl or phenyl column, may also suitable for purifying some polypeptides such as antibodies. Ion exchange chromatography (for example anion exchange chromatography and/or cation exchange chromatography) may also suitable for purifying some polypeptides such as antibodies. Mixed-mode chromatography (for example reversed phase/anion exchange, reversed phase/cation exchange, hydrophilic interaction/anion exchange, hydrophilic interaction/cation exchange, etc.) may also suitable for purifying some polypeptides such as antibodies. Many methods of purifying polypeptides are known in the art. [00156] In some embodiments, the OX40 agonist is produced in a cell-free system. Nonlimiting exemplary cell-free systems are described, for example, in Sitaraman et al., Methods Mol. Biol.498: 229-44 (2009); Spirin, Trends Biotechnol.22: 538-45 (2004); Endo et al., Biotechnol. Adv.21: 695-713 (2003). [00157] In some embodiments, OX40 agonists prepared by the methods described above are provided. In some embodiments, the OX40 agonist is prepared in a host cell. In some embodiments, the OX40 agonist is prepared in a cell-free system. In some embodiments, the OX40 agonist is purified. In some embodiments, a cell culture media comprising an OX40 agonist is provided. [00158] In some embodiments, compositions comprising antibodies prepared by the methods described above are provided. In some embodiments, the composition comprises an OX40 agonist prepared in a host cell. In some embodiments, the composition comprises an Attorney Docket No.01202-0062-00PCT OX40 agonist prepared in a cell-free system. In some embodiments, the composition comprises a purified OX40 agonist. Exemplary methods of treating diseases using OX40 agonists and combination therapies [00159] In some embodiments, methods of treating disease in an individual comprising administering an OX40 agonist, such as hexavalent 3x1D10v6-Fc, are provided. Such diseases include any disease that would benefit from increase proliferation and activation of CD4⁺ and/or CD8⁺ T cells. In some embodiments, methods for treating cancer in an individual are provided. The method comprises administering to the individual an effective amount of an OX40 agonist provided herein. Such methods of treatment may be in humans or animals. In some embodiments, methods of treating humans are provided. [00160] Nonlimiting exemplary cancers that may be treated with OX40 agonists provided herein include basal cell carcinoma, biliary tract cancer; bladder cancer; bone cancer; brain and central nervous system cancer; breast cancer; cancer of the peritoneum; cervical cancer; choriocarcinoma; colon and rectum cancer; connective tissue cancer; cancer of the digestive system; endometrial cancer; esophageal cancer; eye cancer; cancer of the head and neck (e.g., head and neck squamous cell carcinoma (HNSCC)); gastric cancer (e.g, gastric or gastroesophageal junction adenocarcinoma (G/GEA)); gastrointestinal cancer; glioblastoma; hepatic carcinoma; hepatoma; intra-epithelial neoplasm; kidney or renal cancer (e.g., renal cell carcinoma); larynx cancer; liver cancer; lung cancer; small-cell lung cancer; non-small cell lung cancer (NSCLC); adenocarcinoma of the lung; squamous carcinoma of the lung; melanoma (e.g., cutaneous melanoma, mucosal melanoma and ocular/uveal melanoma); myeloma; neuroblastoma; oral cavity cancer; ovarian cancer; pancreatic cancer; prostate cancer; retinoblastoma; rhabdomyosarcoma; rectal cancer; cancer of the respiratory system; salivary gland carcinoma; sarcoma; skin cancer; squamous cell cancer; stomach cancer; testicular cancer; thyroid cancer; uterine or endometrial cancer; cancer of the urinary system (e.g., urothelial (transitional) cell carcinoma (TCC)); and vulval cancer; lymphoma; Hodgkin’s lymphoma; non- Hodgkin’s lymphoma; B-cell lymphoma; low grade/follicular non-Hodgkin's lymphoma (NHL); small lymphocytic (SL) NHL; intermediate grade/follicular NHL; intermediate grade diffuse NHL; high grade immunoblastic NHL; high grade lymphoblastic NHL; high grade small non- cleaved cell NHL; bulky disease NHL; mantle cell lymphoma; AIDS-related lymphoma; Waldenstrom's macroglobulinemia; chronic lymphocytic leukemia (CLL); acute lymphoblastic leukemia (ALL); Hairy cell leukemia; and chronic myeloblastic leukemia. In some embodiments, the cancer is non-small cell lung cancer (NSCLC), melanoma (including cutaneous melanoma, mucosal melanoma, and ocular/uveal melanoma), head and neck Attorney Docket No.01202-0062-00PCT squamous cell carcinoma (HNSCC), gastric or gastroesophageal junction adenocarcinoma (G/GEA), renal cell carcinoma (RCC), or urothelial (transitional) cell carcinoma (TCC). [00161] In some embodiments, the cancer or tumor has a high degree of microsatellite instability (i.e., the cancer or tumor is microsatellite instability (MSI) high) regardless of histology. In some embodiments, the cancer or tumor has a tumor mutational burden of (TMB) of ≥10 mutations/Mb (i.e., the tumor is TMB high), regardless of histology. In some embodiments, the cancer or tumor is deficient for one or more mismatch repair (MMR) proteins, regardless of histology. [00162] The OX40 agonists can be administered as needed to subjects. In some embodiments, an effective dose of an OX40 agonist is administered to a subject one or more times. In some embodiments, an effective dose of an OX40 agonist is administered to the subject daily, about twice a week, about once a week, about once every two weeks, about once every three weeks, about once every four weeks, about once a month, about once every six weeks, etc. With respect to the timing of administration of doses, the term “about” is intended to denote a range that is ±3 days of a recited administration. [00163] An effective dose of an OX40 agonist is administered to the subject at least once. In some embodiments, the effective dose of an OX40 agonist may be administered multiple times, including multiple times over the course of at least a month, at least six months, or at least a year. [00164] In some embodiments, pharmaceutical compositions are administered in an amount effective for treating (including prophylaxis of) cancer and/or increasing T-cell proliferation. The therapeutically effective amount is typically dependent on the weight of the subject being treated, his or her physical or health condition, the extensiveness of the condition to be treated, or the age of the subject being treated. In some embodiments, an OX40 agonist (such as INBRX-106) provided herein may be administered in an amount in the range of about 0.1 mg/kg body weight (abbreviated herein as simply “mg/kg”) to about 0.3 mg/kg per dose. With respect to doses, the term “about” is intended to denote a range that is ±10% of a recited dose, such that for example, a dose of about 0.3 mg/kg will be between 0.27 mg/kg and 0.33 mg/kg. [00165] In some embodiments, a method of treating cancer comprises administering an OX40 agonist (such as INBRX-106) provided herein to a subject with cancer at a dose of about 0.1 mg/kg once about every three weeks. In some embodiments, an OX40 agonist is administered to a subject with cancer at a dose of about 0.3 mg/kg once about every three weeks. [00166] OX40 agonists can be administered alone or in combination with other modes of treatment, such as other anti-cancer agents. They can be provided before, substantially Attorney Docket No.01202-0062-00PCT contemporaneous with, or after other modes of treatment (i.e., concurrently or sequentially). In some embodiments, the method of treatment described herein can further include administering: radiation therapy, chemotherapy, vaccination, targeted tumor therapy, CAR-T therapy, oncolytic virus therapy, cancer immunotherapy, cytokine therapy, surgical resection, chromatin modification, ablation, cryotherapy, an antisense agent against a tumor target, a siRNA agent against a tumor target, a microRNA agent against a tumor target, an anti-cancer/tumor agent, a checkpoint inhibitor, or a biologic, such as an antibody, cytokine, or receptor extracellular domain-Fc fusion. [00167] In some embodiments, a method of treating cancer comprises administering an OX40 agonist concurrently, such as in a particular sequence within a specified time interval, with a second therapeutic agent, for example, an agent that blocks the PD-1 / PD-L1 axis. Examples of agents that block the PD-1 / PD-L1 axis include nivolumab (BMS); cemiplimab (Regeneron), pembrolizumab (Merck); durvalumab (AstraZeneca); atezolizumab (Genentech/Roche); avelumab (Pfizer); AMP-224 (AstraZeneca/Amplimmune); BMS- 936559/MDX-1105 (BMS); AMP-514 (AstraZeneca/Amplimmune); dostarlimab (Tesaro/AnaptysBio); STI-A1010 (Sorrento Therapeutics); STI-A1110 (Sorrento Therapeutics); retifanlimab (Incyte); toripalimab (Shanghai Junshi Biosciences); and other agents that are directed against programmed death-1 (PD-1) or programmed death ligand 1 (PD-L1). [00168] In some embodiments, a method of treating cancer comprises administering an OX40 agonist (such as INBRX-106) in combination with an anti-PD-1 antibody. In some embodiments, an OX40 agonist (such as INBRX-106) is administered in combination with pembrolizumab, nivolumab, dostarlimab, retifanlimab, cemiplimab, or toripalimab. [00169] In some embodiments, a method of treating cancer comprises administering an OX40 agonist (including INBRX-106) provided herein to a subject with cancer at a dose of about 0.1 mg/kg to about 0.3 mg/kg once about every three weeks. In some embodiments, an OX40 agonist is administered at a dose of about 0.1 mg/kg once above every three weeks. In some embodiments, an OX40 agonist is administered at a dose of about 0.3 mg/kg once above every three weeks. In some embodiments, the method further comprises administering to the subject an anti-PD-1 antibody once about every three weeks. In some embodiments, the OX40 agonist (such as INBRX-106) and the anti-PD-1 antibody are administered on the same day. In some embodiments, the OX40 agonist is administered prior to administration of the PD-1 antibody, or the anti-PD-1 antibody is administered prior to administration of the OX40 agonist. [00170] In some embodiments, a method of treating cancer comprises administering a priming dose of an OX40 agonist (such as INBRX-106) provided herein, wherein the priming dose is about 0.3 mg/kg. In some embodiments, the subject is administered one priming dose of Attorney Docket No.01202-0062-00PCT the OX40 agonist. In some embodiments, the subject is administered a maintenance dose of an OX40 agonist, wherein the maintenance dose is about 0.1 mg/kg, and wherein the first maintenance dose is administered about three weeks after the priming dose of the OX40 agonist. In some embodiments, further maintenance doses of the OX40 agonist are administered once about once every three weeks. In some embodiments, the method comprises administering an- anti-PD-1 antibody, wherein the first dose of the anti-PD-1 antibody is administered about three weeks after the priming dose of the OX40 agonist. In some embodiments, further doses of the anti-PD-1 antibody are administered once about every three weeks. In some embodiments, the maintenance dose of the OX40 agonist (such as INBRX-106) and the anti-PD-1 antibody are administered on the same day. In some embodiments, the maintenance dose of the OX40 agonist is administered prior to administration of the PD-1 antibody, or the anti-PD-1 antibody is administered prior to administration of the maintenance dose of the OX40 agonist. [00171] In some embodiments, a method of treating cancer is provided, wherein the method comprises administering an OX40 agonist (such as INBRX-106) provided herein at a dose of about 0.3 mg/kg once about every 6 weeks and administering an anti-PD-1 antibody once about every 6 weeks. In some embodiments, the OX40 agonist, such as the first dose of the OX40 agonist, is administered once about three weeks prior to the administration of the anti- PD-1 antibody, such as the first dose of the anti-PD-1 antibody. In some embodiments, the anti- PD-1 antibody, such as the first dose of the anti-PD-1 antibody, is administered about three weeks prior to the administration of the OX40 agonist, such as the first dose of the OX40 agonist. [00172] In various embodiments, the anti-PD-1 antibody is pembrolizumab, nivolumab, dostarlimab, retifanlimab, cemiplimab, or toripalimab. In some embodiments, the anti-PD-1 antibody is administered at a dose of about 150 mg to about 600 mg, such as about 200 mg, about 240 mg, about 350 mg, about 375 mg, or about 500 mg, for example, once about every three weeks. In some embodiments, the anti-PD-1 antibody is pembrolizumab and is administered at a dose of about 200 mg. In some embodiments, the anti-PD-1 antibody is nivolumab and is administered at a dose of about 240 mg. In some embodiments, the anti-PD-1 antibody is cemiplimab and is administered at a dose of about 350 mg. In some embodiments, the anti-PD-1 antibody is retifanlimab and is administered at a dose of about 375 mg. In some embodiments, the anti-PD-1 antibody is dostarlimab and is administered at a dose of about 500 mg. In some embodiments, the anti-PD-1 antibody is toripalimab and is administered at a dose of about 240 mg. [00173] In some embodiments, the anti-PD-1 antibody is administered at a dose of about 300 mg to about 1200 mg, such as about 400 mg, about 480 mg, about 700 mg, about 750 mg, or Attorney Docket No.01202-0062-00PCT about 1000 mg, for example, once about every six weeks. In some embodiments, the anti-PD-1 antibody is pembrolizumab and is administered at a dose of about 400 mg. In some embodiments, the anti-PD-1 antibody is nivolumab and is administered at a dose of about 480 mg. In some embodiments, the anti-PD-1 antibody is cemiplimab and is administered at a dose of about 700 mg. In some embodiments, the anti-PD-1 antibody is retifanlimab and is administered at a dose of about 750 mg. In some embodiments, the anti-PD-1 antibody is dostarlimab and is administered at a dose of about 1,000 mg. In some embodiments, the anti- PD-1 antibody is toripalimab and is administered at a dose of about 480 mg. [00174] In some embodiments, a subject is treated for at least 6 weeks, at least 12 weeks, at least 18 weeks, at least 24 weeks, at least 30 weeks, at least 36 weeks, at least 42 weeks, or at least 48 weeks. [00175] In some embodiments, OX40 agonists can be administered in vivo by various routes, including, but not limited to, intravenous, intra-arterial, parenteral, intraperitoneal or subcutaneous. In some embodiments, the OX40 agonist (such as INBRX-106) is administered by intravenous infusion. In some embodiments, the OX40 agonist is administered by intravenous infusion over a period of about 30 minutes, about 45 minutes, about 60 minutes, about 75 minutes, a period of about 30-60 minutes, a period of 60-120 minutes, etc. In some embodiments, the anti-PD-1 antibody is administered by intravenous infusion. In some embodiments, the anti-PD-1 antibody is administered by intravenous infusion over a period of about 30 minutes, about 45 minutes, about 60 minutes, about 75 minutes, a period of about 30- 60 minutes, a period of 60-120 minutes, etc. The appropriate formulation and route of administration may be selected according to the intended application. [00176] In some embodiments, a therapeutic treatment using an OX40 agonist is achieved by increasing T-cell proliferation and/or activation. In some embodiments, increasing T-cell proliferation and/or activation inhibits growth of cancer. Pharmaceutical compositions [00177] In some embodiments, compositions comprising OX40 agonists are provided in formulations with a wide variety of pharmaceutically acceptable carriers (see, for example, Gennaro, Remington: The Science and Practice of Pharmacy with Facts and Comparisons: Drugfacts Plus, 20th ed. (2003); Ansel et al., Pharmaceutical Dosage Forms and Drug Delivery Systems, 7^th ed., Lippencott Williams and Wilkins (2004); Kibbe et al., Handbook of Pharmaceutical Excipients, 3^rd ed., Pharmaceutical Press (2000)). Various pharmaceutically acceptable carriers, which include vehicles, adjuvants, and diluents, are available. Moreover, various pharmaceutically acceptable auxiliary substances, such as pH adjusting and buffering agents, tonicity adjusting agents, stabilizers, wetting agents and the like, are also available. Non- Attorney Docket No.01202-0062-00PCT limiting exemplary carriers include saline, buffered saline, dextrose, water, glycerol, ethanol, and combinations thereof. [00178] In some embodiments, a pharmaceutical composition comprises an OX40 agonist at a concentration of at least 10 mg/mL, 20 mg/mL, 30 mg/mL, 40 mg/mL, 50 mg/mL, 60 mg/mL, 70 mg/mL, 80 mg/mL, 90 mg/mL, 100 mg/mL, 125 mg/mL, 150 mg/mL, 175 mg/mL, 200 mg/mL, 225 mg/mL, or 250 mg/mL. Nonlimiting exemplary methods of diagnosis and treatment [00179] In some embodiments, the methods described herein are useful for evaluating a subject and/or a specimen from a subject (e.g. a cancer patient). In some embodiments, evaluation is one or more of diagnosis, prognosis, and/or response to treatment. [00180] In some embodiments, the methods described herein comprise evaluating a presence, absence, or level of a protein. In some embodiments, the methods described herein comprise evaluating a presence, absence, or level of expression of a nucleic acid. The compositions described herein may be used for these measurements. For example, in some embodiments, the methods described herein comprise contacting a specimen of the tumor or cells cultured from the tumor with a therapeutic agent as described herein. [00181] In some embodiments, the evaluation may direct treatment (including treatment with the antibodies described herein). In some embodiments, the evaluation may direct the use or withholding of adjuvant therapy after resection. Adjuvant therapy, also called adjuvant care, is treatment that is given in addition to the primary, main or initial treatment. By way of non- limiting example, adjuvant therapy may be an additional treatment usually given after surgery where all detectable disease has been removed, but where there remains a statistical risk of relapse due to occult disease. In some embodiments, the antibodies are used as an adjuvant therapy in the treatment of a cancer. In some embodiments, the antibodies are used as the sole adjuvant therapy in the treatment of a cancer. In some embodiments, the antibodies described herein are withheld as an adjuvant therapy in the treatment of a cancer. For example, if a patient is unlikely to respond to an antibody described herein or will have a minimal response, treatment may not be administered in the interest of quality of life and to avoid unnecessary toxicity from ineffective chemotherapies. In such cases, palliative care may be used. [00182] In some embodiments the molecules are administered as a neoadjuvant therapy prior to resection. In some embodiments, neoadjuvant therapy refers to therapy to shrink and/or downgrade the tumor prior to any surgery. In some embodiments, neoadjuvant therapy means chemotherapy administered to cancer patients prior to surgery. In some embodiments, neoadjuvant therapy means an antibody is administered to cancer patients prior to surgery. Types of cancers for which neoadjuvant chemotherapy is commonly considered include, for Attorney Docket No.01202-0062-00PCT example, breast, colorectal, ovarian, cervical, bladder, and lung. In some embodiments, the antibodies are used as a neoadjuvant therapy in the treatment of a cancer. In some embodiments, the use is prior to resection. [00183] In some embodiments, the tumor microenvironment contemplated in the methods described herein is one or more of: tumor vasculature; tumor-infiltrating lymphocytes; fibroblast reticular cells; endothelial progenitor cells (EPC); cancer-associated fibroblasts; pericytes; other stromal cells; components of the extracellular matrix (ECM); dendritic cells; antigen presenting cells; T-cells; regulatory T-cells; macrophages; neutrophils; and other immune cells located proximal to a tumor. Kits [00184] Also provided are articles of manufacture and kits that include any of the OX40 agonists described herein, with or without an anti-PD-1 antibody, and suitable packaging. In some embodiments, the invention includes a kit with (i) an OX40 agonist, and (ii) instructions for using the kit to administer the OX40 agonist to an individual. In some embodiments, the invention includes a kit with (i) an OX40 agonist, and (ii) instructions for using the kit to administer the OX40 agonist in combination with an anti-PD-1 antibody to an individual. [00185] Suitable packaging for compositions described herein are known in the art, and include, for example, vials (e.g., sealed vials), vessels, ampules, bottles, jars, flexible packaging (e.g., sealed Mylar or plastic bags), and the like. These articles of manufacture may further be sterilized and/or sealed. Also provided are unit dosage forms comprising the compositions described herein. These unit dosage forms can be stored in a suitable packaging in single or multiple unit dosages and may also be further sterilized and sealed. Instructions supplied in the kits of the invention are typically written instructions on a label or package insert (e.g., a paper sheet included in the kit), but machine-readable instructions (e.g., instructions carried on a magnetic or optical storage disk) are also acceptable. The instructions relating to the use of the antibodies generally include information as to dosage, dosing schedule, and route of administration for the intended treatment or industrial use. The kit may further comprise a description of selecting an individual suitable or treatment. [00186] The containers may be unit doses, bulk packages (e.g., multi-dose packages) or sub-unit doses. For example, kits may also be provided that contain sufficient dosages of molecules disclosed herein to provide effective treatment for an individual for an extended period, such as about any of a week, 2 weeks, 3 weeks, 4 weeks, 6 weeks, 8 weeks, 3 months, 4 months, 5 months, 6 months, 7 months, 8 months, 9 months, or more. Kits may also include multiple unit doses of molecules and instructions for use and packaged in quantities sufficient for storage and use in pharmacies, for example, hospital pharmacies and compounding Attorney Docket No.01202-0062-00PCT pharmacies. In some embodiments, the kit includes a dry (e.g., lyophilized) composition that can be reconstituted, resuspended, or rehydrated to form generally a stable aqueous suspension of antibody. EXAMPLES [00187] The examples discussed below are intended to be purely exemplary of the invention and should not be considered to limit the invention in any way. The examples are not intended to represent that the experiments below are all or the only experiments performed. Efforts have been made to ensure accuracy with respect to numbers used (for example, amounts, temperature, etc.) but some experimental errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, molecular weight is average molecular weight, temperature is in degrees Centigrade, and pressure is at or near atmospheric. Example 1: Hexavalent 3x1D10v6-Fc enhances T cell costimulation and IFNγ production [00188] Enriched T cells from 10 healthy human donors were stimulated with suboptimal anti-CD3 antibody in the presence or absence of hexavalent 3x1D10v6-Fc. [00189] PBMCs were isolated from 10 healthy human donors, and T cell populations were enriched substantially essentially as follows. PBMC isolation: PBMC were isolated from human donor leukapheresis or whole blood samples using density gradient centrifugation, as follows. Blood samples were diluted with PBS/2%FBS (1:2) and 30ml of diluted blood were layered onto 15ml lymphoprep density gradient medium. After centrifugation at 800xg for 30 minutes the PBMC layer at the interphase of plasma and lymphoprep layers was removed and remaining red blood cells were lysed using Red blood cell lysis buffer for 5 minutes at room temperature. Cells were washed in PBS and then frozen fresh in Cryostor at 100x106 cells per ml. [00190] T cell Enrichment: Enriched T cell populations were prepared by labeling non-T cell populations with biotinylated anti-lineage marker antibodies against CD14, CD16, CD19, CD20, CD36, CD56, CD123 and TCR l/d for 20 minutes at room temperature (BioLegend, diluted 1:300). Streptavidin coated magnetic particles were added at 500 μl per 100x106 cells for 20 minutes at room temperature. T cells were negatively enriched by incubating on a magnet twice for 8 minutes at room temperature. Enriched T cells were collected from the unbound fraction and purity was assessed by flow cytometry. [00191] T cell stimulation: Enriched T cells from 10 healthy donors were thawed and washed twice using CTL anti-aggregate media. T cells were labeled with the proliferative dye Attorney Docket No.01202-0062-00PCT CellTrace Violet (CTV) (ThermoFisher) for 10 minutes at 37°C. After washing, T cells were resuspended to 1.5x10⁶ cells/ml in RPMI supplemented with 10% FBS and 1X antibiotic/antimycotic and 150,000 T cells were added per well in 100 µl in a flat-bottom 96- well plate. Prepared anti-CD3 antibody coated beads (Tosylactivated Dynabeads (ThermoFisher) were coated overnight with 200 µg of anti-CD3 antibody (clone OKT3, eBioscience) following the manufacturer’s instructions) were added in 50 µl per well to the labeled T cells at a 1:2 ratio (beads:T cells) to provide a primary T cell stimulus. hexavalent 3x1D10v6-Fc was added in 50 µl at a final concentration of 10 nM. Plates were incubated at 37°C/5% CO₂ for 3 days and analyzed by flow cytometry. [00192] Flow Cytometry: After 3 days, T cells were spun down and labeled in FACS buffer (PBS/2% FBS/0.05% sodium azide) with the viability marker propidium iodide (PI) along with the following fluorescently labeled antibodies: CD4-PE, CD8-APC, CD25-FITC, and CD71-PE/Cy7 (Biolegend) for 20 minutes at room temperature. T cells were washed and resuspended in 70 µl of FACS buffer and analyzed using the Sony SA3800 spectral analyzer. Flowjo software was used to gate on live (PI-) CD4 and CD8 populations and the percentage of cells that underwent proliferation was determined by gating on T cells that underwent a minimum of one division as determined by CTV dilution. The percentage of CD4 and CD8 T cells expressing the activation markers CD25 and CD71 was determined by comparing to non- stimulated T cell populations. The data was exported into Microsoft Excel and graphed using Prism. [00193] Intracellular Cytokine Staining: Cells were spun down and surface labeled with PE-conjugated anti-CD4 antibody and APC-conjugated anti-CD8 antibody along with the Zombie Red viability stain (BioLegend) for 20 minutes at room temperature in FACS buffer (2% FBS/0.1% Sodium Azide in PBS). After washing, the cells were fixed for 30 minutes with BD Fix/Perm buffer. Cells were washed with 1X BD Perm/Wash buffer and labeled with PE/Cy7 anti-IFN ^ antibody in Perm/Wash buffer for 45 minutes at room temperature. After washing, cells were resuspended in FACS buffer and read on the Sony SA3800 spectral analyzer. Data analysis of CD4⁺ and CD8⁺ T cell populations was performed using Flowjo software and graphed using Prism. [00194] In T cells from all 10 of the donors tested, hexavalent 3x1D10v6-Fc treatment led to a significant increase in the percentage of CD4⁺ and CD8⁺ T cells that underwent proliferation in response to anti-CD3 antibody stimulation (FIG.1, FIG.2). Moreover, the percentage of CD4 and CD8 T cells that expressed the activation markers CD25 and CD71 was increased with hexavalent 3x1D10v6-Fc treatment (FIG.2). In a separate experiment, a smaller subset of 4 donors showed an increase in intracellular IFN ^ levels in both T cell subsets following treatment Attorney Docket No.01202-0062-00PCT with hexavalent 3x1D10v6-Fc (FIG.3). Thus, hexavalent 3x1D10v6-Fc provides a potent costimulatory signal to T cells, leading to enhanced activation, proliferation and effector function. Example 2: Hexavalent 3x1D10v6-Fc reverses Treg-mediated suppression of CD4⁺ T cell proliferation [00195] T cell Enrichment: Tregs and conventional CD4⁺ T cells were enriched from fresh, healthy donor PBMCs by using an EasySep Human CD4⁺CD127^lowCD25⁺ regulatory T cell isolation kit (Stemcell) following the manufacturer’s instructions. [00196] T cell Suppression Assay: In order to distinguish the two populations of cells, enriched Tregs and CD4⁺ responder T cells were labeled with the proliferative dyes CellTrace Violet (CTV) and CFSE, respectively, for 10 minutes at 37°C. After washing, Tregs and CD4⁺ T cells were resuspended to 1.5x10⁶ cells/ml in RPMI supplemented with 10% FBS and 1X antibiotic/antimycotic. Tregs were seeded in 50 µl volume yielding 75,000 Tregs/well in a 96- well round-bottom plate. Tregs were incubated overnight at 37°C in the presence of 10 nM of anti-OX40 hexavalent 3x1D10v6-Fc, 10 nM of a conventional (HC/LC) bivalent anti-OX40 antibody, or in the absence of an antibody. In parallel, labeled CD4⁺ responder T cells were activated overnight at 37°C with anti-CD3 coated dynabeads at a 1:2 bead to T cell ratio. The next day, the Treg plate was washed 2X with media to remove the antibodies. Stimulated responder CD4⁺ T cells were added in 100 µl of media delivering 150,000 CD4⁺ T cells/well to the plate containing Tregs at a ratio of 1 Treg for every 2 CD4⁺ responder T cells. Hexavalent 3x1D10v6-Fc or conventional bivalent anti-OX40 antibody were added back in 100 µl of media at a final concentration of 10 nM in duplicate to a subset of the cells. In addition, a group of CD4⁺ responder T cells was included that was not co-incubated with Tregs. The plate was incubated at 37°C/5% CO₂ for 3 days and analyzed by flow cytometry. [00197] Flow Cytometry: After 3 days, T cells were spun down and labeled in FACS buffer (PBS/2% FBS/0.05% sodium azide) with the viability marker propidium iodide (PI) along with the following fluorescently labeled antibodies: CD4-PE, CD25-APC, and CD71-PE/Cy7 (Biolegend) for 20 minutes at room temperature. T cells were washed and resuspended in 70 µl of FACS buffer and analyzed using the Sony SA3800 spectral analyzer. Flowjo software was used to gate on live (PI-) CFSE⁺ responder CD4⁺ or CTV⁺ Treg populations and the percentage of cells that underwent proliferation was determined by gating on responder T cells that underwent a minimum of one division as determined by CFSE dilution. The percentage of responder CD4⁺ T cells expressing the activation markers CD25 and CD71 was determined by Attorney Docket No.01202-0062-00PCT comparing to non-stimulated T cell populations. The data was exported into Microsoft Excel and graphed using Prism. [00198] Stimulation with anti-CD3 coated beads for a total of 4 days led to the proliferation of 66% of responder CD4⁺ T cells (FIG.4). The addition of enriched Tregs to the culture led to a dramatic reduction in responder CD4⁺ T cell proliferation (34% proliferated). Treatment with 10 nM of hexavalent 3x1D10v6-Fc led to near complete recovery of responder CD4⁺ T cell proliferation (62% proliferated). Moreover, the expression of the T cell activation markers CD25 and CD71 were restored to similar levels to the CD4⁺ T cell responders without Treg experimental group. In contrast, treatment with the conventional bivalent anti-OX40 antibody failed to restore CD4⁺ T cell proliferation or increase the expression of CD25 or CD71 relative to the no antibody group. Example 3: Hexavalent 3x1D10v6-Fc Agonism Upregulates PD-L1 Expression on Activated T-Cells [00199] Hexavalent 3x1D10v6-Fc (INBRX-106) binds to OX40, a co-stimulatory receptor that is upregulated on T cells following activation through TCR engagement of immunogenic MHC bound peptides. Treatment of cells in vitro with an anti-CD3 antibody can mimic this primary TCR activation signal, upregulating OX40 and providing a window to observe co- stimulation through increases in T cell proliferation. As described above hexavalent 3x1D10v6- Fc can enhance T cell activation, proliferation. Studies were conducted to explore the dose dependency of hexavalent 3x1D10v6-Fc costimulatory activity in vitro across a broader range of concentrations than previously tested and to assess the effect of hexavalent 3x1D10v6-Fc on PD- L1 upregulation on activated T cells. [00200] PBMC were isolated from human donors, and T cell populations enriched as described in Example 1. [00201] Co-stimulation Assay: Enriched T cells from healthy donors were labeled with the proliferative dye CellTrace Violet (CTV) (ThermoFisher) at a dilution of 1:1000 in 0.1% BSA/PSA for 10 minutes at 37°C. Cells were then plated in triplicate at 150,000 cells per well in round bottom 96-well plates and combined with OKT3-coated beads (Tosylactivated Dynabeads (ThermoFisher) were coated overnight with 200 µg of anti-CD3 antibody (clone OKT3, eBioscience) following the manufacturer’s instructions) at a ratio of 1:2 ratio (beads:T cells). Cultures were incubated in a final culture volume of 200 μl per well for 4 days at 37°C/5% CO2 with a titration of hexavalent 3x1D10v6-Fc starting at a top concentration of 7752 nM and titrating 1:3 across the plate to a final concentration of 0.007 pM. Attorney Docket No.01202-0062-00PCT [00202] Flow Cytometry: After 4 days, T cells were spun down 400xg for 5 minutes and resuspended in 50 μl FACS buffer (PBS/2% FBS/0.05% sodium azide) with the viability marker propidium iodide (PI) along with the following fluorescently labeled antibodies: CD4-PE, CD8- APC/Fire, CD25-FITC, CD71-PE/Cy7 (Biolegend) for 20 minutes at room temperature. In certain assays cells were also labeled with anti-PD-L1-PE antibody (clone MIH1 Invitrogen). T cells were washed with 200 µl of FACS buffer and analyzed using the Novocyte 3000 flow cytometer. The data was exported and analyzed using Microsoft Excel and graphed using GraphPad Prism. [00203] Flowjo software was used to gate on live (PI-) CD4 and CD8 populations and the percentage of cells that underwent proliferation was determined by gating on T cells that underwent a minimum of one division as determined by CTV dilution. Due to inefficient CD8 staining the CD4 negative population was considered CD8 T cells. The percentage of cells that underwent proliferation was determined by gating on cells that exhibited a decrease in CTV staining compared to a T cell only control (unstimulated). Percent proliferation versus no antibody control was graphed and curves were fit to assess a dose-response relationship. PD-L1 expression on activated CD4 and CD8 T cells was also determined. Representative data are shown in FIG.5A-5C. [00204] A dose-dependent increase in proliferation of both CD4+ (FIG.5A) and CD8+ T cells (FIG.5B) was observed when incubated with hexavalent 3x1D10v6-Fc beginning with a concentration of approximately 14 pM and increasing in a dose-dependent manner to around 0.13 nM-0.39 nM, depending on donor. From approximately 0.40 nM to 32 nM responses to hexavalent 3x1D10v6-Fc largely plateaued, but thereafter the costimulatory activity of OX40 began to decrease in a dose-dependent manner, returning to baseline by the maximally tested dose of 7.75 μM. This data suggests that, over a certain threshold concentration, hexavalent INBRX-106 loses the ability to cluster and activate OX40, resulting in lower proliferation. [00205] As shown in FIG.5C, PD-L1 expression on activated T cells exhibited a similar dose-dependent upregulation, plateau, and decrease in a dose-depending manner. PD-L1 upregulation on T cells could be a potential mechanism for T cell dysfunction. In addition to being an activation marker, it can also lead to exhaustion if in chronic inflammatory conditions. PD-L1 ligation to PD-1 impairs TCR signaling and CD28 costimulation, leading to impaired T cell function and tumor escape. Combining hexavalent 3x1D10v6-Fc with an agent that blocks the PD-1/PD-L1 axis, such as an anti-PD-1 antibody. These studies support treatment of patients having PD-L1 expression on their tumor cells with hexavalent 3x1D10v6-Fc in combination with an agent that blocks the PD-1/PD-L1 axis. PD-L1 expression in tumor cells has been established as a clinically relevant cut-off point for treatment with certain PD-l-binding Attorney Docket No.01202-0062-00PCT (or PD-L1 -binding) Molecules. Methods for measuring the extent of PD-L1 expression are known in the art and PD-L1 protein expression may be expressed as a Tumor Proportion Score (TPS), which is the percentage of viable tumor cells showing partial or complete membrane staining at any intensity or by Combined Positive Score (CPS), which is the number of PD-L1 staining cells (tumor cells, lymphocytes, macrophages) divided by the total number of viable tumor cells, multiplied by one hundred. Such PD-L1 expression scores may be determined, in some embodiments, using a test approved for use by a regulatory agency (e.g ., FDA-approved). Various FDA-approved tests are listed on the FDA website: fda.gov/medical-devices/in-vitro- diagnostics/companion-diagnostics, and include, for example, PD-L1 IHC 22C3 pharmDx (Agilent). Example 4: Hexavalent 3x1D10v6-Fc in Combination with Pembrolizumab Potentiates T Cell Activation [00206] Following TCR engagement, costimulatory molecules like OX40 are upregulated alongside negative regulatory molecules, which oppose T cell activation by dampening TCR signaling. Clinically, blockade of one such pathway, the PD-1/PD-L1 axis, has been shown to successfully restore the function of unresponsive tumor-specific T cells, by relieving this inhibitory signal. OX40 achieves a similar outcome, the enhancement of T cells responses, via a different mechanism: providing exogenous costimulatory signals that synergize with TCR signals. These non-overlapping but complementary mechanisms suggest that combining OX40 agonism with checkpoint blockade will achieve greater clinical benefit. [00207] The allogeneic mixed lymphocyte reaction (MLR) is an in vitro assay used to demonstrate functional modulation of T cells; it utilizes a mixture of in vitro-derived immature dendritic cells (iDCs) and HLA mismatched T cells to induce TCR-dependent T cell activation. Hexavalent 3x1D10v6-Fc has been shown to have modest activity in this assay. (Data not shown.) The activity of hexavalent 3x1D10v6-Fc was tested in combination with anti-PD-1 antibody pembrolizumab to determine whether the combination exhibits increased T cell activation. [00208] CD4+ T cell isolation: PBMCs were isolated from human donor blood leukopak using density gradient centrifugation, substantially as follows. Blood samples were diluted with PBS/2% FBS (1:2) and 30 mL of diluted sample was layered onto 15 mL Lymphoprep™ density gradient medium. After centrifugation at 800xg for 30 minutes, the PBMC layer at the interphase of the plasma and Lymphoprep™ was collected and remaining red blood cells were lysed using red blood cell lysis buffer for 7 minutes at room temperature. The PBMCs were then enriched for monocytes as described below, or frozen at 100x10⁶ cells/ml in CryoStor® cryopreservation media and stored in liquid nitrogen. CD4+ T cells were enriched from fresh, Attorney Docket No.01202-0062-00PCT healthy donor PBMCs with the EasySep^TM Human CD4+ T cell isolation kit (Stemcell Technologies) following the manufacturer’s instructions. PBMCs were re-suspended at 50x10⁶ cells/mL in PBS containing 2% FBS and 1mM EDTA. CD4+ T cells were negatively enriched using a CD4+ T cell isolation cocktail followed by incubation with Dextran RapidSpheres™ in an EasySep^TM magnet. After two rounds of enrichment on the magnet, CD4+ T cells were counted and washed with PBS/0.1% BSA (CTV buffer). Cells were labeled with CellTrace™ Violet dye (1:1000) at 10x10⁶ cells/mL in CTV buffer for 10 minutes at 37°C. Labeled cells were washed once with PBS/2% FBS and re-suspended at 3.5x10⁶ cells/mL in assay media (RPMI + 10% FBS plus penicillin, streptomycin, and amphotericin). [00209] Monocyte enrichment and generation of immature dendritic cells (iDC): Monocytes were enriched from PBMC isolated from leukopak donors using a negative enrichment kit without CD16 depletion according to the manufacturer’s protocol (EasySep™ human monocyte enrichment kit without CD16 depletion; Stemcell Technologies). In brief, non- monocyte populations were labeled with tetrameric antibody complexes recognizing anti-lineage markers and depleted using magnetic particles. The unbound cell supernatant contained the monocytes. Monocytes were cultured at 1x10⁶ cells/mL in RPMI supplemented with 10% FBS plus penicillin, streptomycin, and amphotericin, 500 U/mL GM-CSF, and 250 U/mL IL-4. Half of the media was replenished every 2 days until immature dendritic cells (iDC) were harvested on day 7 by collecting loosely adherent and suspended cells. Cells were washed in PBS and then frozen fresh in CryoStor® at 3x10⁶ cells per mL. iDC phenotype induction following this regimen was confirmed by flow cytometry using FSC/SSC size exclusion and detecting CD14- CD11c+ HLA-DR+ staining in at least 60% of the population. [00210] Mixed lymphocyte reaction (MLR): Monocyte-derived immature dendritic cells (iDCs) were re-suspended at 0.8x10⁶ cells/mL in assay media.1.75x10⁵ CD4+ T cells from a different donor were suspended in 50μL, and mixed with 4x10⁴ iDCs in 50 μL in 96-well U- bottom plates. [00211] Hexavalent 3x1D10v6-Fc was added at an initial assay concentration of 10 nM and titrated across the plate 1:4 in triplicate in either the presence or absence of a constant assay concentration of 10 nM pembrolizumab. In a separate experiment, pembrolizumab was added at an initial assay concentration of 50 nM and titrated across the plate 1:4 in triplicate either the presence or absence of a constant assay concentration of 1 nM hexavalent 3x1D10v6-Fc. The fixed concentration of hexavalent 3x1D10v6Fc (1 nM) was selected based on saturating antibody concentrations that showed maximal activity in the T cell co-stimulation assay, and for pembrolizumab (10 nM), the saturating antibody concentration that gave maximal reporter activity in the PD1/PD-L1 blockade assay. All assay plates were incubated at 37°C for 7 days. Attorney Docket No.01202-0062-00PCT [00212] Human IL-2 ELISA: Aliquots of assay supernatant were collected on day 3 to determine human IL-2 concentration by ELISA using the Human IL-2 ELISA MAX™ Deluxe kit (Biolegend) following the manufacturer’s instructions. ELISA MaxiSorp plates were coated overnight with human IL-2 capture antibody, washed then blocked with diluent buffer for an hour. Standard curves were prepared in duplicate from an initial concentration of 1000 pg/mL IL-2, and assay supernatant samples were diluted 1:5 or 1:10 in diluent buffer. Samples and standards were incubated on ELISA plates for two hours, followed by washes and incubation with detection antibody for an hour. Assay plates were washed and incubated with horseradish peroxidase (HRP)-conjugated streptavidin for 30 minutes. After a final wash step, captured human IL-2 was detected on the ELISA plates with the provided substrate solution. The detection reaction was stopped after 10-30 minutes with an equal volume of 1M HCl. The absorbance values at 450nm were read on an EMax® plate reader (Molecular Devices), and the concentrations of human IL-2 in the MLR assay supernatants calculated from the standard curves. [00213] As shown in FIG.6A-6B, the combination of pembrolizumab and hexavalent 3x1D10v6-Fc enhanced the IL-2 production from CD4⁺ T cells in a mixed lymphocyte reaction (MLR). These results demonstrate the benefit of combining PD-1/PD-L1 axis blockade with OX40 agonism. Example 5. Hexavalent 3x1D10v6-Fc in Combination with Pembrolizumab Potentiates T Cell Activation [00214] As described above the combination of pembrolizumab and hexavalent 3x1D10v6-Fc enhanced T cell activation in a mixed lymphocyte reaction (MLR). Additional allogeneic MLR studies were conducted to explore the dose dependency of hexavalent 3x1D10v6-Fc on T cell activation in vitro across a broader range of concentrations than previously tested. [00215] The MLR was performed essentially as described in Example 4 above with the following changes: previously prepared and frozen T cells and iDCs thawed with CTL thawing reagent were used; 4x10⁴ iDCs in 50 μL were seeded in 96-well U-bottom plates, 50 μL of 4x pembrolizumab (final concentration 10 nM) or media and 2.0 x10⁵ CD4+ T cells from a different donor in 50 μL, were added to each well. The plates were incubated for 1 hour at 37° C to allow T cells to begin upregulation of OX40. Hexavalent 3x1D10v6-Fc was added at an initial assay concentration of 7500 nM and titrated across the plate 1:3 for 19 point dilution. Control wells were treated with media or pembrolizumab alone. The assay plates were incubated Attorney Docket No.01202-0062-00PCT at 37°C for 4 days. Once removed from the incubator aliquots of assay supernatant were collected to determine human IL-2 concentration by ELISA as described in Example 4 above. [00216] As shown in FIG.7, the combination of pembrolizumab and hexavalent 3x1D10v6-Fc greatly enhanced the IL-2 production from CD4⁺ T cells in a MLR assay across a broad range of hexavalent 3x1D10v6-Fc. IL-2 secretion exhibited hexavalent 3x1D10v6-Fc dose-dependent upregulation, plateau, and decrease in a dose-depending manner. These results demonstrate the benefit of combining PD-1/PD-L1 axis blockade with OX40 agonism and further suggest that, over a certain threshold concentration, hexavalent INBRX-106 loses the ability to cluster and activate OX40. Example 6: Assessment of Pharmacokinetic Properties of Hexavalent 3x1D10v6-Fc [00217] The pharmacokinetic (PK) properties and the toxicokinetic profile of a therapeutic agent is important for understanding dose/exposure relationships, rate of clearance, and the safety profile. Attenuated exposure and or an accelerated clearance profile can reveal liabilities in the agent itself due to non-specific interactions, poor stability, or immunogenicity; or in the target as evidenced by toxicity or changes in drug disposition. Typically, the PK properties of therapeutic antibodies are assessed in rodents and/or in non-human primates. A poor PK profile in these models may be indicative of non-specific binding and rapid clearance of the antibody. [00218] Hexavalent 3x1D10v6Fc was administered via intravenous injection to cynomolgus monkeys (5 males and 5 females per group) at 5 mg/kg, 20 mg/kg and 60 mg/kg. A quantitative ELISA method was used to determine serum concentrations of hexavalent 3x1D10v6-Fc, substantially as follows. Microplate wells were pre-coated with a recombinant form of the extracellular domain of human OX40 fused to a mouse Fc domain (OX40-mFc). After blocking and washing, a titration of hexavalent 3x1D10v6-Fc (for a standard curve), control samples containing pre-determined concentrations of hexavalent 3x1D10v6-Fc, and test samples were added to the wells and incubated to allow hexavalent 3x1D10v6Fc contained in the samples to bind the immobilized OX40-mFc. Plates were washed, and an Fcγ fragment- specific, horseradish peroxidase (HRP) conjugated anti-human IgG secondary antibody was added to detect plate-bound hexavalent 3x1D10v6Fc. A solution containing the HRP substrate tetramethylbenzidine (TMB) was added to wells, which results in a colorimetric signal that is proportional to the concentration of HRP-conjugated anti-human IgG antibody bound to hexavalent 3x1D10v6-Fc. The reaction was stopped by addition of an acidic solution and absorbance at 450 nm was determined. For control and test samples, the conversion of spectrophotometric absorbance (quantitated by optical density [OD450]) values into Attorney Docket No.01202-0062-00PCT concentration was performed by comparison to a concurrently analyzed calibration curve regressed according to a 4-PL/logistic model. The lower limit of quantitation (LLOQ) of hexavalent 3x1D10v6Fc in serum by this method was 100 ng/mL. [00219] Across the dose range, systemic exposure (Cmax and AUC0-168h) was achieved and increased dose-proportionally, without gender differences. Across the dose range from 5 to 60 mg/kg, average PK parameter estimates a non-compartmental analysis were as follows: the average T1/2 across groups was 55-89.7 hours, clearance rate (CL) was 0.683-0.832 mL/h/kg, and volume of distribution at steady state (Vdss) was 55.9-86.2 mL/kg. The PK profile of hexavalent 3x1D10v6-Fc is shown in FIG.8. [00220] These results demonstrate that hexavalent 3x1D10v6-Fc has a well-behaved PK profile, suitable for therapeutic applications, and suggests the non-specific binding observed with 1D10v1 has been mitigated. Example 7: An Open-Label, Multicenter, First-in-Human, Dose-Escalation, Multicohort, Phase 1/2 Study of Hexavalent 3x1D10v6 and Hexavalent 3x1D10v6 in Combination With Pembrolizumab in Patients With Locally Advanced or Metastatic Solid Tumors [00221] In an initial monotherapy dose escalation study, hexavalent 3x1D10v6-Fc (INBRX-106) was administered to patients via intravenous injection at 0.0003, 0.001, 0.003, 0.01, 0.3, 1 and 3 mg/kg every three weeks (Q3W). Hexavalent 3x1D10v6-Fc was found to be well tolerated, with relatively few drug-related serious adverse events (SAEs), dose limiting toxicities (DLTs), or severe treatment emergent adverse events (TEAEs). [00222] A subsequent expansion of the study was therefore initiated to evaluate the safety, maximum tolerated dose, and anti-tumor activity of hexavalent 3x1D10v6-Fc administered alone or in combination with pembrolizumab. Monotherapy patients are treated with either 0.1 or 0.3 mg/kg hexavalent 3x1D10v6-Fc Q3W. Combination therapy patients are treated with a combination of hexavalent 3x1D10v6-Fc and pembrolizumab as outlined in Tables 3-5 below, where “C1D1, C2D1, C3D1…C35D1” indicate the first day of consecutive three week (21 day) cycles. An initial cohort of combination patients was treated with 0.1 mg/kg hexavalent 3x1D10v6-Fc in combination with 200mg pembrolizumab once every 3 weeks (Q3W) on the same day (Table 3A), optionally additional patients may be treated with 0.3 mg/kg hexavalent 3x1D10v6-Fc in combination with 200mg pembrolizumab Q3W on the same day (Table 3B). Another cohort of combination patients will be treated with a 0.3 mg/kg priming dose of hexavalent 3x1D10v6-Fc, followed by 0.1 mg/kg hexavalent 3x1D10v6-Fc and 200 mg pembrolizumab every 3 weeks on the same day (Table 4). Another cohort of combination patients will be treated with alternating every 6 weeks (Q6W) dosing of 0.3 mg/kg Attorney Docket No.01202-0062-00PCT hexavalent 3x1D10v6-Fc and Q6W 400 mg pembrolizumab, such that hexavalent 3x1D10v6-Fc and pembrolizumab are administered on an alternating schedule three weeks apart (Table 5). A final cohort will be treated with pembrolizumab (200 mg Q3W) alone. For purposes of defining a treatment interval for the duration of these studies, one cycle is defined as 21 days or three (3) weeks. Table 3A. Combination 0.1 mg/kg hexavalent 3x1D10v6-Fc and 200 mg pembrolizumab (FDA approved dose)

Table 3B. Possible Escalation Combination 0.3 mg/kg hexavalent 3x1D10v6-Fc and 200 mg pembrolizumab

Table 4. Priming dose of 0.3 mg/kg hexavalent 3x1D10v6-Fc followed by 0.1 mg/kg hexavalent 3x1D10v6-Fc and 200 mg pembrolizumab

Table 5. Alternating dose of 0.3 mg/kg hexavalent 3x1D10v6-Fc and 400 mg pembrolizumab

[00223] Administration typically occurs at the predetermined frequency or periodicity, or within about 1-3 days of such scheduled interval, such that administration occurs 1-3 days before, 1-3 days after, or on the day of a scheduled dose, e.g., once every 3 weeks (± 0-3 days). [00224] Primary outcome measures include the frequency and severity of adverse events for hexavalent 3x1D10v6-Fc as a single agent and in combination with pembrolizumab. Adverse events will be assessed by the National Cancer Institute Common Terminology Criteria Attorney Docket No.01202-0062-00PCT for Adverse Events (NCI CTCAE), version 5.0. Primary outcome measures also include the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) for hexavalent 3x1D10v6-Fc as a single agent and in combination with pembrolizumab. [00225] Secondary outcome measures include the area under the serum concentration time curve (AUC), maximum observed serum concentration (C_max), trough observed serum concentration (Ctrough), and immunogenicity of hexavalent 3x1D10v6-Fc. These parameters are determined for hexavalent 3x1D10v6-Fc as a single agent and in combination with pembrolizumab. [00226] Other outcome measures include the anti-tumor activity of hexavalent 3x1D10v6- Fc as a single agent and in combination with pembrolizumab. Tumor response is determined by the revised Response Evaluation Criteria in Solid Tumors version 1.1 (RECISTv1.1) and Response Evaluation Criteria in Solid Tumors (iRECIST). [00227] Exploratory Objectives include assessment of pharmacodynamic (PD) biomarkers for hexavalent 3x1D10v6-Fc as single agent and in combination with pembrolizumab (i.e., peripheral CD4+ and CD8+ T cell proliferation, and activation state and OX40 target engagement on memory CD4+ T cells and). Example 8: Assessment of Peripheral Pharmacodynamics of Hexavalent 3x1D10v6-Fc: Memory CD4⁺ T-Cell Activation and Proliferation [00228] Whole blood was collected (e.g., on days 1 (pre and post infusion), 7, 15, and 21 after administration) from patients in the monotherapy dose escalation study (3x1D10v6-Fc dosed at 0.0003, 0.001, 0.003, 0.01, 0.3, 1 and 3 mg/kg) for biomarker evaluation. Samples were sent to a central laboratory for flow cytometry analysis. Whole blood was lysed in RBC Lysis buffer at room temperature for 10 minutes. Cells were washed, resuspended in FACS buffer (2%FBS/PBS) and labeled with the viability dye (live dead aqua, Thermo Fisher) along with the following fluorescently labeled antibodies: CD4-PE (Thermo Fisher), CD3-PerCP, CD8-APC, CD45RO-BV421, PDL1 AF488, and HLA-DR Pecy7 (Biolegend) for 30 minutes at 4°C in the dark. Cells were then washed with FACS buffer, incubated in Fixation Buffer (eBioscience) for 1 hour at room temperature in the dark, washed with Perm buffer (eBioscience) and further labeled with Ki67 AF647 for 30 minutes at 4°C in the dark. The labeled cells were washed with Perm buffer and resuspended in PBS and analyzed on a BD Canto II Flow Cytometer using BD FACSDiva™ Software and FlowJo® Analysis Software Version 10 to gate on memory CD4+ T cells (lymphocyte / single cell /live/ CD3+ / CD4+ CD8- / CCR7+ CD45RO+ cells). Fluorescence intensity was calibrated using Quantum™ MESF kit. The activity (pathway modulation) was measured by examining immune activation Attorney Docket No.01202-0062-00PCT (memory T cell proliferation by Ki67+ expression and activation by HLADR expression). FIG. 9A plots the peak fold change of %HLA-DR expression in memory CD4 T cells, a marker of T cell activation. FIG.9B plots the peak % Ki67 expression in memory CD4 T cells, a marker of T cell proliferation. [00229] As shown in FIG.9A-9B doses of hexavalent 3x1D10v6-Fc between 0.01 and 1.0 mg/kg induce the most robust peripheral memory CD4 T-cell activation, while higher doses between 0.1 and 1.0 mg/kg induce greatest proliferation. The same bell shape activation and proliferation curve was observed in vivo as was observed in vitro, with immune activation dropping off at the higher doses. Example 9: In Vivo Target Engagement on CD4 T cells from Patients Treated with Hexavalent 3x1D10v6-Fc [00230] OX40 is rapidly down regulated upon productive engagement with hexavalent 3x1D10v6-Fc. To evaluate productive target engagement in vivo the change in OX40 on memory CD4 T cells was evaluated from patients in the monotherapy dose escalation study, and in the 0.1 mg/kg hexavalent 3x1D10v6-Fc in combination with 200 mg pembrolizumab Q3W study (See Table 3A). For this analysis whole blood was collected from patients on day 1 pre- infusion (D1 Pre) and at the end of infusion (D1 EOI) and sent to a central laboratory for flow cytometry analysis. For this analysis hexavalent 3x1D10v6-Fc is used to detect OX40. Parallel samples of whole blood was incubated for 30 minutes at 4°C with unconjugated hexavalent 3x1D10v6-Fc (tube 3) or PBS (tubes 1 and 2), then incubated in RBC Lysis buffer at room temperature for 10 minutes. Cells were washed, resuspended in FACS buffer and incubated for 30 minutes at 4°C (in the dark) with AF647 conjugated hexavalent 3x1D10v6-Fc (tubes 2 and 3) or FACS buffer (tube 1). Cells were washed, resuspended in FACS buffer and incubated for 30 minutes at 4°C (in the dark) with AF488 conjugated anti-ideotype antibody (tube 1 and 2) or FACS buffer (tube 3). Cells were washed, resuspended in FACS buffer and labeled with the viability dye (live dead aqua, Thermo Fisher) along with the following fluorescently labeled antibodies: CD4-PE (Thermo Fisher), CD3-PerCP, CD8-PCcy7, and CD45RO-BV421 (Biolegend) for 30 minutes at 4°C in the dark. The labeled cells were washed with Perm buffer and resuspended in PBS and analyzed on a BD Canto II Flow Cytometer using BD FACSDiva™ Software and FlowJo® Analysis Software Version 10 to evaluate to evaluate % AF647 conjugated hexavalent 3x1D10v6-Fc+ (OX40+) memory CD4 T cells (lymphocyte / single cell / live / CD3+ / CD4+ CD8- / CD45RO+). Fluorescence intensity (MESF) was calibrated using Quantum™ MESF kit. In addition, % Bound Receptor, % Free Receptor, and % Attorney Docket No.01202-0062-00PCT Receptor Occupancy on memory CD4 T cells was also evaluated from predose and EOI samples as follows:

[00231] FIG. 10A plots the % change from pre-infusion levels in OX40 positive memory CD4 T cells on day 1 at the end of infusion for patients in the monotherapy dose escalation study. FIG. 10B plots the total OX40 (%) on CD4 memory T cells for 20 patients in the first combination study (see, Table 3A) on day 1 pre-infusion and at the end of infusion over three 21-day treatment cycles (C1, C2, and C3). [00232] As shown in FIG. 10A doses of hexavalent 3x1D10v6-Fc between 0.003 and 1.0 mg/kg induce OX40 downmodulation at the end of infusion. As shown in FIG. 10B hexavalent 3x1D10v6-Fc at 0.1 mg/kg in combination with pembrolizumab also induced OX40 downmodulation at the end of infusion, and OX40 levels were observed to rebound by the end of each 21-day (3 week) cycle. [00233] The disclosure may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting of the disclosure. Scope of the disclosure is thus indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced herein.

Attorney Docket No.01202-0062-00PCT Table of Certain Sequences

Attorney Docket No.01202-0062-00PCT

Claims

Attorney Docket No.01202-0062-00PCT What is claimed is: 1. A method of treating cancer comprising administering to a subject with cancer an OX40 agonist at a dose of about 0.1 mg/kg to about 0.3 mg/kg once about every three weeks. 2. A method of treating cancer comprising administering to a subject with cancer: a) an OX40 agonist at a dose of about 0.1 mg/kg to about 0.3 mg/kg once about every three weeks; and b) an anti-PD-1 antibody once about every three weeks; wherein the OX40 agonist comprises three VHH domains that bind OX40 and an Fc region, wherein each VHH domain comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 2, a CDR2 comprising the amino acid sequence of SEQ ID NO: 3, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 4. 3. The method of claim 1 or claim 2, wherein the OX40 agonist is administered at a dose of 0.1 mg/kg. 4. The method of claim 1 or claim 2, wherein the OX40 agonist is administered at a dose of 0.3 mg/kg. 5. The method of any one of claims 1-5, wherein the OX40 agonist and the anti-PD- 1 antibody are administered on the same day. 6. The method of any one of claims 1-5, wherein the OX40 agonist is administered prior to administration of the anti-PD-1 antibody. 7. The method of any one of claims 1-5, wherein the anti-PD-1 antibody administered prior to administration of the OX40 agonist. 8. A method of treating cancer comprising administering to a subject with cancer: a) a priming dose of an OX40 agonist, wherein the priming dose is about 0.3 mg/kg; b) a maintenance dose of an OX40 agonist, wherein the maintenance dose is about 0.1 mg/kg, wherein the first maintenance dose is administered about three weeks after the priming dose of the OX40 agonist, and wherein the maintenance dose is administered once about once every three weeks; and c) an-anti-PD-1 antibody, wherein the first dose of the anti-PD-1 antibody is administered about three weeks after the priming dose of the OX40 agonist, wherein the anti-PD-1 antibody is administered once about every three weeks; wherein the OX40 agonist comprises three VHH domains that bind OX40 and an Fc region, wherein each VHH domain comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 2, a CDR2 comprising the amino acid sequence of SEQ ID NO: 3, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 4. Attorney Docket No.01202-0062-00PCT 9. The method of claim 7, wherein the method comprises administering one priming dose. 10. The method of claim 8 or claim 9, wherein the maintenance dose of the OX40 agonist and the anti-PD-1 antibody are administered on the same day. 11. The method of any one of claims 8-10, wherein the maintenance dose of the OX40 agonist is administered prior to administration of the anti-PD-1 antibody. 12. The method of any one of claims 8-10, wherein the anti-PD-1 antibody administered prior to administration of the maintenance dose of the OX40 agonist. 13. The method of any one of claims 2-12, wherein the anti-PD-1 antibody is pembrolizumab, nivolumab, dostarlimab, retifanlimab, cemiplimab, or toripalimab. 14. The method of any one of claims 2-13, wherein the anti-PD-1 antibody is pembrolizumab. 15. The method of any one of claims 2-13, wherein the anti-PD-1 antibody is nivolumab. 16. The method of any one of claims 2-13, wherein the anti-PD-1 antibody is dostarlimab. 17. The method of any one of claims 2-13, wherein the anti-PD-1 antibody is retifanlimab. 18. The method of any one of claims 2-13, wherein the anti-PD-1 antibody is cemiplimab. 19. The method of any one of claims 2-13, wherein the anti-PD-1 antibody is toripalimab. 20. The method of claims 2-19, wherein the anti-PD-1 antibody is administered at a dose of about 150 mg to about 600 mg. 21. The method of any one of claims 2-20, wherein the anti-PD-1 antibody is administered at a dose of about 200 mg, about 240 mg, about 350 mg, about 375 mg, or about 500 mg. 22. The method of any one of claims 2-13, wherein the anti-PD-1 antibody is pembrolizumab and is administered at a dose of about 200 mg. 23. The method of any one of claims 2-13, wherein the anti-PD-1 antibody is nivolumab and is administered at a dose of about 240 mg. 24. The method of any one of claims 2-13, wherein the anti-PD-1 antibody is toripalimab and is administered at a dose of about 240 mg. 25. The method of any one of claims 2-13, wherein the anti-PD-1 antibody is cemiplimab and is administered at a dose of about 350 mg. Attorney Docket No.01202-0062-00PCT 26. The method of any one of claims 2-13, wherein the anti-PD-1 antibody is retifanlimab and is administered at a dose of about 375 mg. 27. The method of any one of claims 2-13, wherein the anti-PD-1 antibody is dostarlimab and is administered at a dose of about 500 mg. 28. A method of treating cancer comprising administering to a subject with cancer: a) an OX40 agonist at a dose of 0.3 mg/kg once about every 6 weeks; and b) an anti-PD-1 antibody once about every 6 weeks; wherein the OX40 agonist and anti-PD-1 antibody are administered on an alternating schedule about three weeks apart, and wherein the OX40 agonist comprises three VHH domains that bind OX40 and an Fc region, wherein each VHH domain comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 2, a CDR2 comprising the amino acid sequence of SEQ ID NO: 3, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 4. 29. The method of claim 28, wherein the first dose of the OX40 agonist is administered about three weeks prior to the administration of the anti-PD-1 antibody. 30. The method of claim 28, wherein the first dose of the anti-PD-1 antibody is administered about three weeks prior to the administration of the OX40 agonist. 31. The method of any one of claims 28-30, wherein the anti-PD-1 antibody is pembrolizumab, nivolumab, dostarlimab, retifanlimab, cemiplimab or toripalimab. 32. The method of any one of claims 28-30, wherein the anti-PD-1 antibody is pembrolizumab. 33. The method of any one of claims 28-30, wherein the anti-PD-1 antibody is nivolumab. 34. The method of any one of claims 28-30, wherein the anti-PD-1 antibody is dostarlimab. 35. The method of any one of claims 28-30, wherein the anti-PD-1 antibody is retifanlimab. 36. The method of any one of claims 28-30, wherein the anti-PD-1 antibody is cemiplimab. 37. The method of any one of claims 28-30, wherein the anti-PD-1 antibody is toripalimab. 38. The method of any one of claims 28-37, wherein the anti-PD-1 antibody is administered at a dose of about 300 mg to about 1200 mg. 39. The method of any one of claims 28-37, wherein the anti-PD-1 antibody is administered at a dose of about 400 mg, about 480 mg, about 700 mg, about 750 mg, or about 1000 mg. Attorney Docket No.01202-0062-00PCT 40. The method of any one of claims 28-30, wherein the anti-PD-1 antibody is pembrolizumab and is administered at a dose of about 400 mg. 41. The method of any one of claims 28-30, wherein the anti-PD-1 antibody is nivolumab and is administered at a dose of about 480 mg. 42. The method of any one of claims 28-30, wherein the anti-PD-1 antibody is toripalimab and is administered at a dose of about 240 mg. 43. The method of any one of claims 28-30, wherein the anti-PD-1 antibody is cemiplimab and is administered at a dose of about 700 mg. 44. The method of any one of claims 28-30, wherein the anti-PD-1 antibody is retifanlimab and is administered at a dose of about 750 mg 45. The method of any one of claims 28-30, wherein the anti-PD-1 antibody is dostarlimab and is administered at a dose of about 1000 mg. 46. The method of any one of claims 2-45, wherein the anti-PD-1 antibody is administered by IV infusion. 47. The method of any one of the preceding claims, wherein the OX40 agonist is administered by intravenous (IV) infusion. 48. The method of any one of the preceding claims, wherein the cancer is basal cell carcinoma, biliary tract cancer; bladder cancer; bone cancer; brain and central nervous system cancer; breast cancer; cancer of the peritoneum; cervical cancer; choriocarcinoma; colon and rectum cancer; connective tissue cancer; cancer of the digestive system; endometrial cancer; esophageal cancer; eye cancer; cancer of the head and neck; or gastroesophageal junction adenocarcinoma (G/GEA); glioblastoma; hepatic carcinoma; hepatoma; intra-epithelial neoplasm; kidney or renal cancer; larynx cancer; liver cancer; lung cancer; small-cell lung cancer; non-small cell lung cancer (NSCLC); adenocarcinoma of the lung; squamous carcinoma of the lung; melanoma; myeloma; neuroblastoma; oral cavity cancer; ovarian cancer; pancreatic cancer; prostate cancer; retinoblastoma; rhabdomyosarcoma; rectal cancer; cancer of the respiratory system; salivary gland carcinoma; sarcoma; skin cancer; squamous cell cancer; stomach cancer; testicular cancer; thyroid cancer; uterine or endometrial cancer; cancer of the urinary system; vulval cancer; lymphoma; Hodgkin’s lymphoma; non-Hodgkin’s lymphoma; B- cell lymphoma; low grade/follicular non-Hodgkin's lymphoma (NHL); small lymphocytic (SL) NHL; intermediate grade/follicular NHL; intermediate grade diffuse NHL; high grade immunoblastic NHL; high grade lymphoblastic NHL; high grade small non-cleaved cell NHL; bulky disease NHL; mantle cell lymphoma; AIDS-related lymphoma; Waldenstrom's macroglobulinemia; chronic lymphocytic leukemia (CLL); acute lymphoblastic leukemia (ALL); Hairy cell leukemia; or chronic myeloblastic leukemia. Attorney Docket No.01202-0062-00PCT 49. The method of any one of the preceding claims, wherein the cancer is NSCLC, melanoma (including cutaneous melanoma, mucosal melanom and ocular/uveal melanoma), head and neck squamous cell carcinoma (HNSCC), gastric or gastroesophageal junction adenocarcinoma (G/GEA), renal cell carcinoma (RCC), or urothelial (transitional) cell carcinoma (TCC). 50. The method of any one of the preceding claims, wherein the cancer is microsatellite instability (MSI) high. 51. The method of any one of the preceding claims, wherein the cancer is tumor mutational burden (TMB) high. 52. The method of any one of the preceding claims, wherein the cancer is deficient for at least one mismatch repair (MMR) protein. 53. The method of any one of claims preceding claims, wherein the subject has received previous treatment with a checkpoint inhibitor. 54. The method of any one of claims 1-52, wherein the subject is checkpoint inhibitor naïve. 55. The method of any one of the preceding claims, wherein a sample of the cancer has been determined to express PD-L1. 56. The method of claim 55, wherein the sample of the cancer has a combined positive score (CPS) ≥ 1%. 57. The method of claim 55 or claim 56, wherein the sample of the cancer has a tumor proportion score (TPS) ≥ 1%. 58. The method of any one of the preceding claims, wherein each VHH domain of the OX40 agonist is humanized. 59. The method of any one of the preceding claims, wherein each VHH domain of the OX40 agonist comprises the amino acid sequence of SEQ ID NO: 1. 60. The method of any one of the preceding claims, wherein the OX40 agonist comprises the amino acid sequence of SEQ ID NO: 9. 61. The method of any one of the preceding claims, wherein the Fc domain of the OX40 agonist comprises an amino acid sequence selected from SEQ ID NOs: 12-15. 62. The method of claim 61, wherein the Fc domain comprises the amino acid sequence of SEQ ID NO: 12 or 13. 63. The method of any one of the preceding claims, wherein the OX40 agonist comprises the amino acid sequence of SEQ ID NO: 10 or 11. 64. The method of any one of the preceding claims, wherein the OX40 agonist is a homodimer under physiological conditions. Attorney Docket No.01202-0062-00PCT 65. The method of any one of the preceding claims, wherein the OX40 agonist is INBRX-106. 66. The method of any one of the preceding claims, wherein the subject is treated for at least 6 weeks, at least 12 weeks, at least 18 weeks, at least 24 weeks, at least 30 weeks, at least 36 weeks, at least 42 weeks, or at least 48 weeks.