586 Multicenter real-life data of subsequent chemotherapy after progression to niraparib in a maintenance relapse setting

Introduction/Background Despite impressive progression free survival (PFS) results from PARP inhibitors (PARPi) in ovarian cancer (OC), concerns about their effect on post-progression treatment outcomes have recently arisen, particularly in the relapsed setting. Mechanisms of overlapping resistance between PARPi and platinum have been suggested, and optimal therapy after PARPi progression is unknown. The aim of this study is to describe outcomes of subsequent chemotherapy after niraparib progression in recurrent platinum sensitive OC, focusing both on platinum rechallenge and no platinum-based chemotherapy. Methodology In this exploratory analysis, data from high-grade serous or endometrioid OC patients who received subsequent chemotherapy after progression to niraparib in the recurrent setting in 17 MITO centers, were collected and analyzed. Primary endpoint of this analysis was overall response rate (ORR). Results Two hundred and thirty-one patients with progressive disease to niraparib were included in this study: 101 patients had a platinum free interval (PFI) of less than 6 months and 130 patients a PFI > 6 months. Among these, 136 women (59%) were evaluable for response to the subsequent chemotherapy after progression on niraparib. In the group of patients with PFI 6 months was 26.3% (2 CR and 14 PR) and clinical benefit rate (CBR) was 47.6%. Fifty-five patients in this group received platinum-based chemotherapy and reported an ORR of 29%. The remaining 16 women with PFI >6 months were treated with pegylated liposomal doxorubicin (PLD) in combination with trabectedin: no responses were reported in this cohort of patients. Conclusion Patients who experienced disease progression following niraparib treatment 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. Disclosures The authors declare no disclosures.