Introduction/Background 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.

Methodology 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 initiation of PARPi therapy, including 10 (11.0%) who progressed within 6 months of their penultimate therapy. Of the 44 patients who experienced disease progression more than 6 months following penultimate therapy, 32 (72.7%) were rechallenged with platinum-based chemotherapy. Of these, 16 (50.0%) experienced further disease progression with 14 (43.8%) progressing within 6 months of their platinum rechallenge. Median PFS following platinum rechallenge was 4.4 months, significantly lower than expected. Platinum resistance was seen in 26.4% of the overall population including 44.4% of the population who experienced disease progression after initiation of PARPi therapy.

Conclusion Patients who experienced disease progression following PARPi therapy showed a poor response to subsequent platinum-based chemotherapy, even when progression occurred more than 6 months after completion of their 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.

Disclosures None.