Study of GS-2426 in Participants With Advanced Solid Tumors

Key Inclusion Criteria: * Participants 18 years of age or older (≥ 19 years old for participants in South Korea). * Histologically or cytologically confirmed advanced malignant solid tumors, who have progressed on, are intolerant to or are ineligible for standard therapy, or have no standard treatment options. * Participant tumors are methylthioadenosine phosphorylase (MTAP)-deficient. * Adequate organ function * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 * All participants must provide a pretreatment tumor tissue sample. Key Exclusion Criteria: * Participants with plans to breastfeed during the study period or within 7 days following the last dose of study intervention. * Have not recovered (ie, returned to Grade 1 or baseline) from clinically significant adverse events (AEs) due to a previously administered agent or a previous intervention as assessed by the investigator. * Active second malignancy. Individuals with a history of malignancy who have been completely treated with no evidence of active cancer for 5 years prior to enrollment, or individuals with surgically cured tumors with low risk of recurrence may be enrolled. * Requirement for ongoing therapy with any prohibited medications . * Prior therapy with a protein arginine methyltransferase 5 (PRMT5) inhibitor or methionine adenosine transferase 2a (MAT2A) inhibitor. * Have serious infection requiring antibiotics within 14 days prior to the first dose. * Uncontrolled concurrent disease…