An Investigational Study of BG-75202 Alone and in Combination With Other Therapeutic Agents in Adults With Advanced Solid Tumors

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.