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.