A Phase 1a/1b, Open-Label Study Evaluating the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Preliminary Antitumor Activity of BG-75098 Alone and in Combination With Other Agents in Patients With Advanced Solid Tumors

This study will be conducted in 2 phases: Phase 1a Dose Escalation and Phase 1b Dose Expansion.

Inclusion Criteria:

• Participants must have measurable disease as assessed by RECIST v1.1.
• Participants must have a stable Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1.
• Participants must have adequate organ function.
• Dose Escalation Part A: Participants with histologically or cytologically confirmed advanced, metastatic, or unresectable solid tumors potentially associated with cyclin-dependent kinase 2 (CDK2) dependency. Participants should have received prior treatment with available standard-of-care (SOC) systemic therapies for advanced/metastatic disease, or for whom standard therapy is not available or not tolerated.
• Dose Escalation Part B: Patients with histologically or cytologically confirmed advanced, metastatic, or unresectable solid tumors who have received ≥ 1 prior line of systemic therapy in the metastatic setting.
• Dose Expansion Cohort 1: Participants with histologically or cytologically confirmed advanced, metastatic, or unresectable CDK4/6 inhibitor-progressed solid tumors.
• Dose Expansion Cohort 2: Participants with advanced solid tumors. Participants with primary platinum refractory disease are not eligible. Participants should have received ≥ 1 line of platinum-containing chemotherapy and ≤ 4 prior therapeutic regimens in the advanced/metastatic setting.

Exclusion Criteria:

• For all cohorts: Prior therapy selectively targeting CDK2 inhibition or degradation.
• For combination cohorts: Prior therapy selectively targeting CDK4. Prior CDK4/6 inhibitor standard of care therapy is permitted and required in local regions where it is approved and available.
• Participants with active leptomeningeal disease or uncontrolled, untreated brain metastasis.

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