Benefits of PARP inhibitor rechallenge in patients with platinum-sensitive recurrent ovarian cancer previously treated with a PARP inhibitor: A Multicenter Retrospective Study

Background : Although poly(ADP-ribose) polymerase (PARP) inhibitor rechallenge has been explored for platinum-sensitive recurrent ovarian cancer, data in Japanese patients remain scarce. This retrospective study evaluated the safety and efficacy of PARP inhibitor rechallenge in this population. Patients and Methods : Twenty-eight Japanese patients with ovarian cancer who experienced platinum-sensitive recurrence during or after PARP inhibitor therapy and subsequently responded to platinum-based chemotherapy were included. Olaparib and niraparib were administered as PARP inhibitor rechallenge in 19 and 9 patients, respectively. The primary endpoint was progression-free survival (PFS), and secondary endpoints were overall survival (OS) and adverse events (AEs). Results : The median follow-up period was 19 months (range, 3–47). Median PFS and OS in the overall population were 6 months (95% CI, 3–8) and 32 months (95% CI, 28–not reached), respectively. The median PFS for patients who had received two prior regimens was 6 months, compared with 5 months for those who had received three or more regimens, with no significant difference (p = 0.734). Grade ≥3 hematologic toxicities included neutropenia (n = 4), anemia (n = 7), and thrombocytopenia (n = 2). Non-hematologic toxicities included interstitial pneumonia, hypertension, and proteinuria, with one case each. No treatment-related deaths occurred. Conclusion s: PARP inhibitor rechallenge in Japanese patients with platinum-sensitive recurrent ovarian cancer demonstrated a manageable safety profile but limited efficacy. Larger, prospective studies incorporating molecular stratification are required to better define the clinical role of PARP inhibitor rechallenge.