Introduction/Background Standard treatment for patients with first platinum-sensitive relapse of epithelial ovarian cancer (EOC) is based on surgery and second-line systemic chemotherapy. Hyperthermic intra-peritoneal chemotherapy (HIPEC) is still considered an experimental treatment.

Methodology The CHIPOR international multicentre randomised phase III trial (NCT01376752), conducted in 31 institutions, enrolled patients with a first peritoneal sensitive relapse (platinum-free interval of ≥6 months) of EOC. Patients were treated with 6 cycles of platinum-based chemotherapy, followed by complete debulking cytoreductive surgery. Patients were enrolled after completing chemotherapy and intraoperatively randomly assigned to receive HIPEC (cisplatin 75 mg/m2 at 41°C for 60 min) or not. Randomisation was performed intra-operatively after complete (CC0-CC1) cytoreductive surgery. Stratification factors were centre, surgical outcome (no residual disease vs residual <0.25 cm), chemotherapy-free interval at relapse (6–12 vs 12¬–18 vs >18 months), and planned 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), quality of life and pain, safety, and postoperative (≤60 days after surgery) morbidity and mortality.

Results Between May 11, 2011, and May 14, 2021, 415 patients were randomised. Baseline characteristics were well balanced between treatment arms. At the data cutoff (8 January, 2023, median follow-up 6.2 years), 272 patients (65%) had died. Efficacy results (OS, PFS, time to subsequent therapy, post-operative mortality, morbidity, QoL) will be presented.

Conclusion 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.

Disclosures LILLY - GLAXOSMITHKLINE