Efficacy and safety of nivolumab plus chemotherapy in patients with advanced gastric cancer with massive ascites.

[BACKGROUND] Chemotherapy with an immune checkpoint inhibitor is one of the standard regimens for treating advanced gastric cancer (AGC). Ascites and peritoneal dissemination are common complications and poor prognostic factors of AGC; however, reports regarding its efficacy and safety in patients with AGC and massive ascites are limited.

[AIM] To evaluate the safety and efficacy of nivolumab combined with chemotherapy in patients with AGC and ascites.

[METHODS] We retrospectively collected clinical data from 124 patients with AGC who received chemotherapy plus nivolumab as first-line treatment from July 2017 to December 2024. Based on computed tomography scans, massive or moderate ascites were classified as high ascites burden (HAB), whereas mild or no ascites were classified as low ascites burden.

[RESULTS] Ascites was detected in 47 patients (38%); 26 (21%) were classified into the HAB group. Patients in the HAB group exhibited a significantly poorer performance status, a higher prevalence of diffuse-type histology, and lower programmed cell death ligand 1 (PD-L1) expression. Combination therapy with FOLFOX and neutropenia was significantly more common in the HAB group. Progression-free survival (PFS) (4.4 months 9.3 months, = 0.0012) and overall survival (OS) (7.3 months 21.2 months, < 0.0001) were significantly poorer in the HAB group. However, an improvement in ascites was observed in 61.5% of patients in the HAB group. PD-L1 expression did not correlate with either PFS or OS in the HAB group.

[CONCLUSION] Nivolumab plus chemotherapy demonstrated modest efficacy and acceptable toxicity in patients with AGC and HAB.