Pamiparib Monotherapy for Patients with Germline BRCA1/2-Mutated Ovarian Cancer Previously Treated with at Least Two Lines of Chemotherapy: A Multicenter, Open-Label, Phase II Study

Purpose: Phase I results of this phase I/II study showed that pamiparib 60 mg twice a day had antitumor activity and an acceptable safety profile in Chinese patients with advanced cancer, including epithelial ovarian cancer. Patients and Methods: This open-label phase II study was con-ducted in China and enrolled adult (>= 18 years) patients with plat-inum-sensitive ovarian cancer (PSOC; disease progression occurring >= 6 months after last platinum treatment) or platinum-resistant ovarian cancer (PROC; disease progression occurring <6 months after last platinum treatment). Eligible patients had known or sus-pected deleterious germline BRCA mutation (gBRCA(mut)) and had previously received >= 2 lines of therapy. Pamiparib 60 mg orally twice day was administered until disease progression, toxicity, or patient withdrawal. The primary endpoint was objective response rate (ORR) assessed by independent review committee (IRC) per RECIST version 1.1. Results: In the total patient population (N = 113; PSOC, n = 90; PROC, n = 23), median age was 54 years (range, 34-79) and 25.6% of patients received >= 4 prior systemic chemotherapy lines. Median study follow-up was 12.2 months (range, 0.2-21.5). Eighty-two patients with PSOC and 19 patients with PROC were evaluable for efficacy. In patients with PSOC, 8 achieved a complete response (CR) and 45 achieved a partial response (PR); ORR was 64.6% [95% confidence interval (CI), 53.3-74.9]. In patients with PROC, 6 achieved a PR; ORR was 31.6% (95% CI, 12.6-56.6). Frequently reported grade >= 3 adverse events were hematologic toxicities, including anemia and decreased neutro-phil count. Conclusions: Pamiparib 60 mg twice a day showed antitumor activity with durable responses in patients with PSOC or PROC with gBRCA(mut), and had a manageable safety profile.