BRCA1/2 Mutation or Not

Breast cancer is the most common malignancy in women; approximately 5-10% are hereditary, with 14% of triple-negative breast cancers (TNBC) harboring BRCA mutations. BRCA1/2 are essential for homologous recombination repair of DNA double-strand breaks, whereas PARP mediates base-excision repair of single-strand breaks. PARP inhibitors (PARPi) exploit synthetic lethality to selectively eliminate BRCA-deficient tumor cells. Olaparib and talazoparib have demonstrated superior PFS and ORR versus chemotherapy in BRCA-mutated, HER2-negative advanced breast cancer, leading to FDA approval. In ovarian cancer, PARPi maintenance improves overall survival, with consistent benefits observed in Asian populations. The domestically developed PARPi fluzoparib, engineered with a trifluoromethyl moiety for enhanced stability and tissue penetration, showed in the phase III FABULOUS trial a median PFS of 6.7 vs 3.0 months and an ORR of 43.6% vs 23.3% compared with chemotherapy in gBRCA-mutated, HER2-negative breast cancer, with manageable safety. Data remain limited in Chinese patients and those with BRCA wild-type disease. This study aims to evaluate the efficacy and safety of fluzoparib maintenance monotherapy in advanced TNBC patients-either BRCA1/2-mutated or wild-type-who have derived clinical benefit from prior platinum-based therapy.