Abstract
BACKGROUND: Nivolumab therapy is a standard-of-care treatment for heavily pretreated patients with advanced gastric cancer (AGC). Previous studies have reported improvement in the objective response rate to chemotherapy after nivolumab therapy for other types of cancer. This study evaluated the efficacy and safety of chemotherapy after nivolumab therapy in AGC. PATIENTS AND METHODS: We conducted a prospective, multicenter, observational study in pretreated patients with nivolumab-refractory or -intolerant AGC. Patients received irinotecan, oxaliplatin-containing regimens, or trifluridine/tipiracil. The primary endpoint was overall survival. RESULTS: A total of 199 patients were included (median age: 69 years; male: 70%; female: 30%). Median overall survival and progression-free survival were 7.5 months [95% confidence interval (CI): 6.7-9.7 months] and 2.9 months (95% CI: 2.2-3.5 months), respectively. Objective response and disease control rates were 16.8% (95% CI: 11.6% to 23.6%) and 18.9% (95% CI: 38.9% to 54.6%), respectively. A prognostic index using alkaline phosphatase and the Glasgow Prognostic Score was generated to classify patients into three risk groups (good, moderate, and poor). The hazard ratios of the moderate and poor groups to the good group were 1.88 (95% CI: 1.22-2.92) and 3.29 (95% CI: 1.92-5.63), respectively. At the initiation of chemotherapy, 42 patients had experienced immune-related adverse events due to prior nivolumab therapy. The most common grade 3-4 adverse events were neutropenia (7.5%), anemia (8.0%), and anorexia (7.5%). CONCLUSIONS: The administration of cytotoxic chemotherapy after nivolumab therapy may give rise to a synergistic antitumor effect in AGC. Further investigation is warranted to confirm these findings.