Hyperthermic intraperitoneal chemotherapy in platinum-sensitive relapsed epithelial ovarian cancer: The CHIPOR randomized phase III trial

5510 Background: Standard treatment for patients with first platinum-sensitive relapse of epithelial ovarian cancer (EOC) is based on surgery and second-line systemic chemotherapy (CT). The role of hyperthermic intra-peritoneal chemotherapy (HIPEC) remains uncertain. Methods: The CHIPOR multicentric randomized phase III trial (NCT01376752), conducted in 31 institutions, enrolled patients with a first platinum-sensitive relapse (platinum-free interval of ≥6 months) of EOC. Patients were treated with 6 cycles of platinum and taxane based CT ± bevacizumab, and those amenable to a complete cytoreductive surgery at the end of CT were enrolled and randomly assigned to receive HIPEC (cisplatin 75 mg/m² at 41°C for 60 min) or not. Randomization was performed during complete cytoreductive surgery, stratified by center, surgical outcome (no residual disease vs residual <0.25 cm), chemotherapy-free interval before relapse, and PARP inhibitor use (yes vs no). The primary endpoint was overall survival (OS). The target sample size was 404 evaluable patients, providing 80% power at 5% alpha after 268 deaths. Secondary endpoints included progression-free survival (PFS), peritoneal PFS, patient-reported outcomes, safety, and postoperative morbidity and mortality (≤60 days after surgery). Results: Between May 11, 2011, and May 14, 2021, 415 patients were randomized. Baseline characteristics were balanced between treatment arms. At the data cutoff (Jan 8, 2023), with a median follow-up of 6.2 years, 268 patients (65%) had died. Efficacy results are summarized below. Conclusions: HIPEC significantly improves OS and peritoneal PFS of women with first platinum-sensitive relapse of EOC treated with second-line platinum-based CT followed by secondary complete cytoreductive surgery. Ongoing analyses, including patient reported outcome, BRCA status, bevacizumab exposure, and subsequent therapy, will be presented. Clinical trial information: NCT01376752 . [Table: see text]