Inclusion Criteria

          -  Male or female, 18-75 years of age at the time of consent.

          -  Provide written informed consent.

          -  Subjects with advanced and/or metastatic histologically or cytologically confirmed
             solid tumor who have not responded or progressed after standard therapies or for whom
             no further standard therapy exists or standard therapy is not available

          -  Patients who are refractory or relapsed to prior anti-CTLA4 checkpoint inhibitors will
             also be recruited if they meet all eligibility criteria.

          -  Eastern Cooperative Oncology Group (ECOG) performance status < 2.

          -  Adequate organ and bone marrow function

          -  Women of childbearing potential (WOCBP) must have a negative serum pregnancy test
             within the 7 days prior to study

        Exclusion Criteria:

          -  Pregnant or nursing females.

          -  Treatment with any investigational drug within 4 weeks prior to the first dose of
             study drug

          -  Grade ≥ 3 irAEs or irAE that lead to discontinuation of prior immunotherapy. Untreated
             or uncontrolled central nervous system (CNS) tumors or metastases

          -  Any active autoimmune disease or documented history of autoimmune disease.

          -  Infection of human immunodeficiency virus (HIV), hepatitis B virus (HBV), or hepatitis
             C virus (HCV)

          -  Subjects requiring systemic treatment with corticosteroids or other immunosuppressive
             medications within 21 days before the planned first dose of study drug.

          -  Current or prior history of pneumonitis, hepatitis, nephritis, colitis or thyroiditis.
             Peripheral neuropathy ≥ Grade 2.

          -  History of clinically significant cardiac disease.

          -  Uncontrolled current illness.