PIPAC in patients with peritoneal metastases from gastrointestinal tract (PIPOX): An open label, non-comparative phase 1/2 dose escalation and expansion trial.

e15561 Background: Withmodern systemic chemotherapy, survival remain poor for patient withadvanced isolated peritoneal metastases from gastrointestinal tract. We aimed to assess the safety and efficacy of PIPAC to oxaliplatin in combination or not with systemic chemotherapy. Methods: We did a phase 1/2, open label, non-comparative, dose escalation and expansion trial of PIPAC to oxaliplatin forpatients with peritoneal cancer index (PCI) more than 5, 13 and 15 for respectively a gastric, small bowell and colorectal cancer primary; who had received at least three months of systemic chemotherapy. PIPAC cycle lengths was 4 to 6 weeks with systemic chemotherapy allowed 15 days after each PIPAC. PCI and oxaliplatin concentration tumor was assessed every PIPAC cycles. Main endpoints were, tolerability, tumor response and survival. Results: Between2017 to 2020, 34 for patients were enrolled in three centers, in this phase 1/2 study of whom 25 were evaluable at recommanded dose of phase I of 90 mg/m 2 plus systemic 5-FU. At this dose, safety profile showed acceptable tolerability. 8 patients (32%) had grade 3/4 treatment related adverse event. Minors (grade 1/2) adverse events were mainly abdominal pain (n = 19, 76%) and nausea (n = 16, 64%). Before inclusion patients received a median of 2 1-4 chemotherapy lines and had a median PCI of 22.5 7-29. Median PFS was 6.1 months and median OS was 13 months. Conclusions: In patients with advanced and refractory peritoneal metastasis, PFS of 6.1 months is encouraging. A prospective randomized phase II study is required. Clinical trial information: NCT03294252 .