The Association Between Location of BRCA Mutation and Efficacy of PARP Inhibitor as a Frontline Maintenance Therapy in Advanced Epithelial Ovarian Cancer

Abstract

Background: The location of BRCA mutations within functional domains may affect sensitivity to poly (ADP-ribose) polymerase (PARP) inhibitors and platinum-based chemotherapy. This study aimed to evaluate the progression-free survival (PFS) benefit from the PARP inhibitor in relation to the location of mutations in BRCA1/BRCA2 in newly diagnosed ovarian cancer.

Materials and methods: Patients with advanced stage III-IV epithelial ovarian cancer who had deleterious BRCA1 or BRCA2 were analyzed. PFS and clinical and molecular data were compared between patients who received olaparib or niraparib as frontline maintenance therapy and those who did not. Subgroup analyses were conducted based on the location of BRCA mutations within the functional domain or the ovarian cancer cluster region (OCCR).

Results: Of the 380 patients, 242 (63.7%) harbored BRCA1 mutation, 137 (36.1%) harbored BRCA2, and one (0.3%) harbored both BRCA1 and BRCA2. With a median follow-up of 35.8 months, the DNA binding domain in BRCA1 (HR, 0.34; 95% CI, 0.15-0.79; p = 0.01) and BRCA2 (HR, 0.25; 95% CI, 0.08-0.78; p = 0.01) demonstrated particularly significant benefit. In patients who harbored BRCA1 mutation in the C-terminal domain (BRCT), no statistically significant PFS benefit from PARP inhibitor was observed (HR, 0.76; 95% CI, 0.39-1.52; p = 0.44). PFS benefit from PARP inhibitor maintenance was observed in both OCCR (HR, 0.49; 95% CI, 0.32-0.74; p < 0.01) and non-OCCR (HR, 0.51; 95% CI, 0.27-0.63; p < 0.01).

Conclusions: Frontline PARP inhibitor maintenance therapy demonstrated a significant PFS benefit in patients with BRCA1/2 mutations, with particularly pronounced benefits for those with mutations located in the DBD of BRCA1 and BRCA2. However, the benefit was less evident for patients with BRCA1 mutations located in the BRCT domain.