475 PARP inhibitors maintenance therapy in platinum-sensitive relapsed ovarian cancer: a comprehensive cancer centre's experience

Introduction/Background* Olaparib and niraparib are poly ADP-ribose polymerase inhibitors (PARPis) that have shown efficacy as maintenance treatment in platinum-sensitive relapsed ovarian cancer (PSROC). The aim of this study was to assess the effectiveness and safety of maintenance PARPis in patients with PSROC, in a comprehensive cancer centre. Methodology We retrospectively evaluated patients with PSROC treated with maintenance olaparib (400mg bid, capsules or 300mg bid, tablets) and niraparib (300mg id), who received ≥2 previous lines of platinum-based chemotherapy (ChT) and had a partial or complete response to the last platinum-based regimen. Patients who received olaparib were BRCA 1/2 mutated (germline and/or somatic) and those who received niraparib were BRCA 1/2 wild-type. Study endpoints were progression-free survival (PFS), overall survival (OS) and adverse events (AEs). Result(s)* Between May 2016 and December 2020, 35 patients received maintenance PARPis (21 received olaparib and 14 received niraparib). Median age was 55 years (43-75), and all had ECOG ≤1. The majority had an ovary primary tumour location (74.3%) with serous histology (85.7%). Most patients (65.7%) received 2 prior platinum regimens; 22 (62.9%) had partial response and 13 (37.1%) had complete response to last platinum-based ChT. Median follow-up was 15.1 months (1.8-60.1), with 26 patients alive (61.9% olaparib and 92.8% niraparib patients alive). Median PFS was 7.0 months (95%CI 4.3-9.7) [median PFS for BRCA 1/2 mutated and BRCA 1/2 wild-type patients was 8.3 (95%CI 6.0-10.6) and 5.9 (95%CI 2.3-9.4) months, respectively]. There were no differences in PFS by number of prior platinum regimens, response to last platinum-based ChT or time-to-progression after penultimate platinum-based ChT (>6-12 vs >12 months). Median OS was not reached. Grade ≥3 AEs (anaemia, thrombocytopaenia, neutropaenia and nausea) occurred in 11 (31.4%) patients (17.1% with olaparib and 14.3% with niraparib). Treatment was suspended in 24 (68.6%) patients: 20 (57.2%) due to progression (34.3% with olaparib and 22.9% with niraparib) and 3 (8.6%) due to toxicity to niraparib (none due to olaparib). Eighteen (51.4%) patients required dose reduction due to AEs (28.6% with olaparib and 22.8% with niraparib). Conclusion* Maintenance PARPis in real-world setting is effective and has a safe toxicity profile.