Inclusion Criteria:

        Histologically proven, locally advanced unresectable or metastatic solid tumors for whom no
        approved therapy with demonstrated clinical benefit is available or standard treatment was
        declined. Patients enrolled to Cohort H (endometrial cancer 500 mg Q4W) must have MSI-H or
        dMMR endometrial cancer, as determined by a local laboratory using IHC or PCR methods and
        must also have tissue (fresh or archival) available for central confirmation of diagnosis

          -  Expansion cohort(s): Progression during or following at least 1, and up to 5, previous
             systemic therapies, consistent with the standard of care for the specific tumor type.

          -  Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

          -  Life expectancy ≥ 12 weeks

          -  Measurable disease

          -  Acceptable laboratory parameters

        Exclusion Criteria:

          -  Symptomatic central nervous system (CNS) metastases.

          -  For Cohort Expansion, patients who have previously received an immune checkpoint
             inhibitor (e.g., anti-PD-L1, anti-PD-1, anti-CTLA-4) are not eligible for this study.

          -  Patients with any history of known or suspected autoimmune disease with the specific
             exceptions of vitiligo, resolved childhood atopic dermatitis, psoriasis not requiring
             systemic treatment (within the past 2 years), and patients with a history of Grave's
             disease that are now euthyroid clinically and by laboratory testing.

          -  Treatment with any systemic anti-neoplastic therapy, or investigational therapy within
             the 4 weeks prior to the initiation of study drug administration.

          -  Treatment with radiation therapy within 2 weeks prior to the initiation of study drug
             administration.

          -  Clinically significant cardiovascular disease

          -  Clinically significant pulmonary compromise, including a requirement for supplemental
             oxygen use to maintain adequate oxygenation.

          -  Presence of active pneumonitis or history of non-infectious pneumonitis.

          -  Clinically significant gastrointestinal disorders

          -  Evidence of active viral, bacterial, or systemic fungal infection requiring parenteral
             treatment within 7 days prior to the initiation of study drug. Patients requiring any
             systemic antiviral, antifungal, or antibacterial therapy for active infection must
             have completed treatment no less than one week prior to the initiation of study drug

          -  Known history of positive testing for human immunodeficiency virus or history of
             acquired immune deficiency syndrome.

          -  Known history of hepatitis B or hepatitis C infection or known positive test for
             hepatitis B surface antigen, hepatitis B core antigen, or hepatitis C polymerase chain
             reaction (PCR)

          -  Vaccination with any live virus vaccine within 4 weeks prior to the initiation of
             study drug administration. Inactivated annual influenza vaccination is allowed

          -  Dementia or altered mental status that would preclude understanding and rendering of
             informed consent