PARP (poly ADP-ribose polymerase) is one of the genes involved in the DNA repair system, and its inhibitors are developed for combating BRCA-mutated cancers. Several PARP inhibitors have been approved to treat BRCA-mutated ovarian cancer.
However, only one PARP inhibitor is currently approved for HER2 negative breast cancer patients with BRCA mutation, and clinical data of PARP inhibitors on BRCA-mutated breast cancers is still scarce. Therefore, researchers conducted a phase III open-label EMBRACA trial recruiting 431 metastatic or locally advanced breast cancer patients harboring germline BRCA1 or BRCA2 mutations to evaluate the efficacy and safety of talazoparib, one of the PARP inhibitors, in BRCA-mutated breast cancer. The results showed that the medium progression free-survival (PFS) was 8.6 vs 5.6 months in the talazoparib and chemotherapy group, respectively. Moreover, talazoparib reduced the risk of disease progression by 46% comparing to chemotherapy in advanced breast cancer patients with BRCA mutations. The objective response rates (ORR) were 62.6% in talazoparib group and 27.2% in chemotherapy group. The safety profile showed that the most common grade 3 and 4 non-hematologic adverse effects in talazoparib group were vomiting, back pain and dyspnea, at 2.4 % each. These findings suggest that talazoparib may be effective in BRCA-mutated breast cancer for future clinical use.