Retrospective analysis for the efficacy and safety of nivolumab in advanced gastric cancer patients according to ascites burden

Background Nivolumab is a standard later-line therapy for advanced gastric cancer (AGC). However, few reports exist about its efficacy and safety in patients with massive ascites. Methods We retrospectively collected clinical data from 72 AGC patients who received nivolumab administration at least once from Oct 2017 to Feb 2019 and studied their clinical outcomes dividing into two groups: 50 patients with no or localized ascites in the pelvic cavity or liver surface (LAB: low ascites burden) and 22 patients with massive ascites (HAB: high ascites burden). Results Median overall survival (OS) was 5.3 months (95% CI 3.4–7.3) in the LAB group and 2.5 months (95% CI 0.0–5.0) in the HAB group. Multivariate Cox regression analysis for OS revealed blood neutrophil-to-lymphocyte ratio (hazard ratio 0.40, 95% CI 0.20–0.83, p = 0.013) as an independent prognostic factor. Response rates in the patients with measurable lesions were 16% (7/43) and 8% (1/12) in the LAB and HAB groups, respectively. Ascites decreased or disappeared in 6 HAB patients (27%) and these responders had a prolonged OS of median 9.7 months (95% CI 3.6–15.8). The median time to ascites response was 1.3 months (95% CI 0.8–1.9). These responders have lower neutrophil-to-lymphocyte ratios than 5.0 at the start of nivolumab. Immune-related adverse events occurred in 23% of HAB and 18% of LAB patients. Conclusions Nivolumab could improve massive ascites and confer survival benefit for some AGC patients. Considering a similar incidence of immune-related adverse events, it would be a recommended treatment option for AGC with massive ascites.