An Investigational Study of BG-89894 Tablets in Participants With Advanced Solid Tumors

Key Inclusion Criteria: * Must sign a written informed consent and willing to comply with all study-related procedures and requirements. * Age ≥18 years (or the legal age of consent according to local regulations). * Histologically or cytologically confirmed diagnosis of advanced, metastatic, or unresectable solid tumors that have progressed on or after standard therapy, or for which no appropriate standard therapy is available. * Evidence of Methylthioadenosine phosphorylase (MTAP) homozygous deletion or loss of MTAP expression in tumor tissue. * Participants must be able to provide an archived tumor tissue sample or unstained fresh biopsy if there is no archival tissue at baseline. * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 and evidence of adequate organ function and bone marrow reserve, as defined in the study protocol. Key Exclusion Criteria: * History of other malignancies or concurrent active malignancies within 3 years. * Prior treatment with methionine adenosyltransferase 2 alpha (MAT2A) inhibitors (e.g., AG-270, IDE397) or methylthioadenosine (MTA)-cooperative protein arginine methyltransferase 5 (PRMT5) inhibitors (e.g., AMG193). * Uncontrolled or active central nervous system (CNS) disease, including untreated or symptomatic brain metastases, spinal cord compression, or leptomeningeal carcinomatosis. * Active bleeding, history of major bleeding events within the past 6 months, or tumors associated with a high risk of vascular invasion. * Receipt of systemic anticancer therapy, radiation therapy, live vaccine, or major surgical procedures within protocol-specified washout periods. * Active or uncontrolled infections, including tuberculosis (TB), (COVID-19, known human immunodeficiency virus (HIV) infection, or uncontrolled hepatitis B virus (HBV) infection. Note: Additional eligibility criteria may apply.