Inclusion Criteria

• Must have a histologically or cytologically confirmed solid tumor.
• Must have a locally advanced or metastatic solid tumor.
• Has progressed or is intolerant to any standard treatment regimen, has refused standard treatment, or adequate standard therapy does not exist.
• Has an evaluable lesion per guidelines of Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1.
• Has an Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1.
• A woman of child-bearing potential or a man who is sexually active with a woman of child-bearing potential must agree to use adequate contraception, from the time of signing of the Informed Consent Form, through the duration of study participation, and for 23 weeks after the last dose of IMP for women or 31 weeks after the last dose of IMP for men.
• Has adequate hematological, renal, hepatic and respiratory functions defined as:
  • White blood cell count ≥ 2.0 × 109/L (2000/ mm3);
  • Absolute neutrophil count > 1.5 × 109/L (1500/mm3);
  • Platelets > 100 × 109/L (100000/mm3);
  • Hemoglobin ≥ 10.0 g/dL (6.2 mmol/L);
  • Serum total bilirubin ≤ 1.5 × ULN (except subjects with Gilbert syndrome, who can have total bilirubin < 3.0 mg/dL);
  • AST and ALT ≤ 3 × ULN;
  • Serum creatinine ≤ 1.5 × ULN OR calculated creatinine clearance (CrCL) ≥ 50 mL/min (using the Cockcroft-Gault formula):
    • Female CrCL = (140-age in years) × weight in kg × 0.85
      • 72 x serum creatinine in mg/dL
    • Male CrCL = (140-age in years) × weight in kg × 1.00
      • 72 x serum creatinine in mg/dL.
• Is willing to undergo tumor biopsy during the screening period:
  • If the tumor is inaccessible for biopsy, archived tumor material must be available for submission.
• Voluntarily sign and date Institutional Review Board approved informed consent form in accordance with regulatory and institutional guidelines.

Exclusion Criteria

• Is pregnant or breast-feeding, or expecting to conceive or father a child during this study.
• Has uncontrolled and significant inter-current illness.
• Has psychiatric illness/social situations that in the opinion of the investigator would limit compliance with study requirements.
• Has known central nervous system (CNS) metastases and/or carcinomatous meningitis.
• Has received prior therapy for cancer or major surgery within 28 days, or 42 days for nitrosourea or mitomycin C, prior to cycle 1 day 1.
• Has received radiotherapy or radiosurgery within 14 days prior to cycle 1 day 1.
• Has been previously treated with an anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137, or anti-CTLA-4 antibody or any other antibody or drug specifically targeting T-cell co-stimulation or checkpoint pathways.
• Has been previously treated with mogamulizumab.
• Has a history of allergy or hypersensitivity to study drug components.
• Has received a live, attenuated vaccine within 28 days prior to cycle 1 day 1.
• Has a history of organ transplant or allogeneic bone marrow transplant.
• Has any unresolved toxicity grade > 1 from previous anti-cancer therapy.
• Subject use of immunosuppressive medication within 14 days before the Cycle 1 Day 1: 
  • Note: Inhaled, ocular, intranasal, intra-articular, or topical corticosteroids are allowed;
  • Non-immunosuppressive doses of systemic steroids for adrenal replacement or for contrast allergy are allowed.
• Subject has an active autoimmune disease or a history of autoimmune disease which may affect vital organ function or require immune suppressive treatment including systemic corticosteroids;
• These include but are not limited to subjects with a history of immune-related neurologic disease, multiple sclerosis, uveitis, autoimmune (demyelinating) neuropathy, Guillain-Barré syndrome, myasthenia gravis; transverse myelitis; systemic autoimmune disease such as systemic lupus erythematosus, connective tissue diseases, scleroderma, autoimmune hepatitis.  Exceptions:
  • Subject with vitiligo, alopecia, type I diabetes mellitus, and endocrine deficiencies including hypothyroidism managed with replacement hormones including physiologic corticosteroids are eligible;
  • Subject with psoriasis controlled with topical medication, or conditions not expected to recur in the absence of an external trigger (precipitating event) are eligible.
• Has history of toxic epidermal necrolysis or Stevens-Johnson syndrome.
• Has a history of inflammatory bowel disease, Crohn's disease, ulcerative colitis, celiac disease, or Wegener's granulomatosis.
• Has primary or acquired immunodeficiency or known history of testing positive for human immunodeficiency virus (HIV) or known acquired immunodeficiency syndrome.
• Tests positive for hepatitis B surface antigen (HBVsAg) or hepatitis C RNA indicating acute or chronic infection.
• Has another active malignancy requiring concurrent intervention.
• Is receiving any other investigational agents.
• Has another condition that, in the opinion of the Investigator and/or Sponsor, would interfere with evaluation of the IMP or interpretation of subject safety or study results.
• Has a history of pneumonitis or interstitial lung disease.