Key Inclusion Criteria:

          -  Dose Escalation Cohorts: Histologically or cytologically confirmed advanced malignant
             solid tumor that is refractory to or intolerant of all standard therapy or for which
             no standard therapy is available.

          -  Dose Expansion and 1000 mg BID Dose Escalation Cohorts: Individuals must have
             available sufficient and adequate formalin fixed tumor sample preferably from a biopsy
             of a tumor lesion obtained either at the time of or after the diagnosis of advanced
             disease has been made and from a site not previously irradiated. Alternatively,
             individuals must agree to have a biopsy taken prior to entering the study to provide
             adequate tissue. For the 1000 mg BID dose escalation cohort, individuals with
             melanoma, Merkel cell, microsatellite instability-high (MSI-H) cancers, and classical
             Hodgkin lymphoma (cHL) are not required to have archival or fresh biopsy tissue.

          -  Dose Escalation Biopsy Substudy and 1000 mg BID Dose Escalation Cohorts: Documented
             ligand 1 of programmed cell death protein 1 (PD-L1) expression in the tumor (tumor
             proportion score (TPS) ≥ 10% or combined positive score (CPS) ≥ 10). In the 1000 mg
             BID Cohort, PD-L1 expression will not be required for Merkel cell, melanoma, MSI-H
             cancers, and cHL.

          -  Eastern Cooperative Oncology Group (ECOG) Performance Status of ≤ 2.

          -  Adequate organ function.

        Key Exclusion Criteria:

          -  History or evidence of clinically significant disorder, condition, or disease that, in
             the opinion of the Investigator or Medical Monitor would pose a risk to individual
             safety or interfere with the study evaluations, procedures, or completion.

          -  Dose Escalation Cohorts: History of ≥ Grade 3 Adverse Events (AEs) during prior
             treatment with an immune checkpoint inhibitor, or history of discontinuation of
             treatment with an immune checkpoint inhibitor due to AEs.

          -  Dose Escalation 1000 mg BID and Dose Expansion Cohort: Prior treatment with an immune
             checkpoint inhibitor (anti-PD-1, anti-PD-L1, or anti- ligand 2 of programmed cell
             death protein 1 (PD-L2) antibodies).

          -  History of autoimmune disease (for example, systemic lupus erythematosus, rheumatoid
             arthritis, inflammatory bowel disease, vascular thrombosis associated with
             antiphospholipid syndrome, Wegener's granulomatosis, Sjögren's syndrome, Bell's palsy,
             Guillain-Barré syndrome, multiple sclerosis, autoimmune thyroid disease, vasculitis,
             or glomerulonephritis).

        Note: Other protocol defined Inclusion/Exclusion criteria may apply.