Introduction Maintenance therapy with PARP inhibitors (PARPi) can increase progression free survival (PFS) in recurrent or metastatic platinum-sensitive epithelial ovarian cancer (EOC), though some evidence suggests a decreased response to subsequent platinum-based chemotherapy. This study assessed real-world response rates to platinum-based chemotherapy for recurrent high grade EOC following treatment with a PARPi.

Methods Single center retrospective cohort study of patients prescribed a PARPi as maintenance therapy for recurrent or metastatic EOC, including 54 patients on niraparib and 36 patients on olaparib. Median duration of follow-up after PARPi initiation was 16.3 months.

Results Of the 91 patients included in the analysis, 54 (59.3%) experienced disease progression after PARPi therapy, including 10 (11.0%) who progressed within 6 months of their penultimate therapy. Of the 44 patients with disease progression more than 6 months following penultimate therapy, 32 (72.7%) were rechallenged with platinum-based chemotherapy. Of these, 14 (43.8%) further progressed within 6 months of their platinum rechallenge. Median PFS following platinum rechallenge was 4.4 months. Incidence of platinum resistance was 26.4% in the overall population and 44.4% in those with disease progression after initiation of PARPi therapy.

Conclusion/Implications Disease progression following PARPi therapy showed a poor response to subsequent platinum-based chemotherapy, even when progression occurred more than 6 months after the penultimate platinum-based chemotherapy. This supports the theory that PARPi resistance correlates with platinum resistance and raises concern for possible contribution of PARPi in the induction of platinum resistance in recurrent EOC.