HIPEC combined with camrelizumab, paclitaxel and S-1 for conversion therapy in patients with advanced gastric cancer with peritoneal metastasis: A prospective phase II clinical study.

e16017 Background: This phase II study aimed to evaluate the efficacy and safety of systemic chemoimmunotherapy and hyperthermic intraperitoneal chemotherapy (HIPEC) combined with cytoreductive surgery (CRS) for the treatment of gastric cancer (GC) patients with peritoneal metastasis (PM). Methods: The Initial systemic treatment comprised two cycles of HIPEC and four cycles of chemoimmunotherapy. HIPEC was administered intraperitoneally with paclitaxel (75 mg/m 2 ). For chemoimmunotherapy, paclitaxel and camrelizumab was administered intravenously on day 1(paclitaxel,150 mg/m 2 ; camrelizumab,200mg), and S-1 was administered orally(80mg/m 2 /day)on days 1–14 of a 3-week cycle. Another two cycles of HIPEC and four cycles of chemoimmunotherapy were administered after second diagnostic staging laparoscopy or CRS. The primary endpoints were treatment efficacy; the secondary endpoint was 3-year overall survival (OS). Results: A total of 48 patients were enrolled and 46 patients were analyzed. Of these, 15 patients received only chemoimmunotherapy and HIPEC (palliative treatment group), while 31 (67.4%) patients received systemic chemoimmunotherapy, HIPEC and CRS (conversion therapy group).The R0 resection rate in the conversion therapy group was 90.3%(28/31).Median OS was markedly improved in the conversion therapy group in comparison with the palliative chemotherapy group((28.1 months vs. 10.2 months, p＜0.0001). Grade 3 or 4 adverse events were identified in 7 (22.6%) patients in conversion therapy group and 3 (20.0%) patients in conversion therapy group, with no significant difference (P = 0.842). Conclusions: Systemic chemoimmunotherapy and HIPEC combined with CRS is safe and feasible, and could potentially improve the prognosis of gastric cancer patients with limited peritoneal metastasis. However, further clinical trials are still warranted.