1068 Platinum-sensitive ovarian cancer recurrence after PARP-inhibitor maintenance at first line: a real-world scenario

Introduction/Background The impact of PARP-inhibitors on disease progression and distribution upon recurrence remains largely unexplored, with potential implications for subsequent therapies, including local treatments such as secondary cytoreductive surgery (SCS) or stereotactic radiotherapy. This study aims to delineate the incidence and recurrence pattern following first-line maintenance treatment with PARP-inhibitors in a real-world scenario and to describe the treatment strategies offered to these patients. Methodology We retrospectively identified all patients who underwent first-line PARPi, from January 2019 to December 2022 in our Institution. Recurrence sites and number of lesions were assessed by CT or PET-CT scans. The flow chart of patients' population is detailed in figure 1. Results A total of 365 cases were identified, but 45 (12.3%) patients received a combination of PARP-inhibitor and bevacizumab. Of the remaining 320 patients, 167 (52.2%) had a BRCA mutation. With a median follow-up of 32 months (IQR 23 – 44.75), 162 of 320 patients (50.6%) experienced disease recurrence, of which 126 (77.8%) had a platinum-free interval (PFI) exceeding 6 months. 87.3% of the recurrence occurred during PARP-inhibitor administration. In 52.2% of cases, the recurrence occurred as oligometastatic. Among platinum sensitive women, 123 patients were treated at recurrence, 71 (57.7%) received second-line chemotherapy, 36(29.2%) underwent SCS, and 16(13.0%) were treated with radiotherapy. In the overall population, the risk of recurrence was lower in patients with BRCA mutations (HR 0.337, pConclusion In patients treated with first-line PARP inhibitor maintenance, there is a general shift toward a longer median PFS and median PFI compared to general population before PARPi. Most of the recurrences were observed during treatment and over half of the patients experienced oligometastatic disease. Where feasible, local treatment significantly improves overall survival. Disclosures Nothing to disclose.