Study of GS-5319 Given Alone or in Combination in Adults With Solid Tumors

This study includes four arms, Parts A, B, C, and D. Participants in Parts A, B, and D are assigned non-randomized. Participants in Part C are assigned using a randomization procedure.

Key Inclusion Criteria:

• Participants diagnosed with histologically or cytologically confirmed solid tumor types who have progressed despite standard therapy, are intolerant to standard therapy, or are ineligible for standard therapy in the advanced setting (locally-advanced or metastatic).
• Participant tumors are methylthioadenosine phosphorylase (MTAP)-deficient. Deoxyribonucleic acid (DNA) sequencing may be assessed locally such as by local next-generation sequencing (NGS) or by central laboratory assay when available.
• Eastern Cooperative Oncology Group (ECOG) performance status score of 0 to 1.
• Adequate organ function
• Age ≥ 18yrs old ( ≥ 19 years old for patients in South Korea)
• Participants must meet the following tissue requirements:

• pretreatment tumor tissue is required

Key Exclusion Criteria:

• Active second malignancy. Participants with a history of malignancy who have been completely treated, with no evidence of active cancer for 3 years prior to enrollment, or participants with surgically cured tumors with low risk of recurrence may be enrolled.
• Positive serum pregnancy test or participant who is breastfeeding.
• Requirement for ongoing therapy with any prohibited medications.
• Have not recovered (ie, returned to Grade 1 or baseline) from adverse events (AEs) due to a previously administered agent.
• Active and clinically relevant bacterial, fungal, or viral infection that is not controlled or requires systemic antibiotics, antifungals, or antivirals, respectively.
• Ascites or pleural effusion that is symptomatic and/or requiring medical intervention.
• Active human immunodeficiency virus (HIV)/hepatitis B virus (HBV)/hepatitis C virus (HCV) infection

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