Testing a new targeted medicine alone and in combination with other treatments in people with advanced breast cancer and other solid cancers.A Phase 1a/1b Study Evaluating the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Preliminary Antitumor Activity of BG-75202, Alone and in Combination With Other Agents in Patients With Advanced Solid Tumors

Inclusion

• Part 1A: Participants with histologically or cytologically confirmed advanced, metastatic breast cancer and other solid tumors who have exhausted, are intolerant of all available standard of care therapies, and/or without available standard of care therapies.
• Part 1B and Part 2A: Participants with advanced breast cancer with 1 to 3 prior lines of systemic therapy in the metastatic setting. Prior lines in the advanced/ metastatic setting may not exceed 2 lines of chemotherapy (inclusive of antibody-drug conjugate with cytotoxic payload).
• Parts 2B and 2C: Participants with advanced breast cancer enrolled in regions where cyclin-dependent kinase 4/6 (CDK4/6) inhibitors are not approved and/or not available as the first-line treatment and who are CDK4/6 inhibitor treatment naïve and did not receive any previous systemic treatment for advanced disease.
• Participants with breast cancer must have histologically or cytologically confirmed advanced breast cancer at the time of most recent testing, based on American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines.
• Female participants with metastatic breast cancer must be postmenopausal or receiving ovarian function suppression treatment.
• Measurable disease as assessed by Response Evaluation Criteria in Solid Tumors (RECIST) v 1.1.
• Stable Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1.
• Adequate organ function.