430P Efficacy of CDK4/6 Inhibitors in BRCA-Mutated HR+/HER2- Metastatic Breast Cancer: Turkish Oncology Group (TOG) Study

Abstract

Germline BRCA mutations (gBRCAm) occur in ∼5-10% of breast cancer patients, with approximately 60% presenting as HR+/HER2- disease. While CDK4/6 inhibitors have demonstrated significant efficacy in unselected HR+/HER2- metastatic breast cancer (MBC), emerging evidence suggests potentially reduced benefit in gBRCAm patients. A recent meta-analysis reported inferior PFS and OS for gBRCAm versus wild-type patients. This study evaluates real-world outcomes of CDK4/6 inhibitor therapy in gBRCAm HR+/HER2- MBC patients.