Evaluation of Prognostic Factors for Unresectable or Recurrent Gastric Cancer Treated with Nivolumab.

PURPOSE: Nivolumab is useful for the treatment of unresectable/recurrent gastric cancer as third-line or later chemotherapy. However, the factors that predict the efficacy of nivolumab monotherapy remain unclear. METHODS: We retrospectively studied the predictive factors of response in 59 consecutive patients treated with nivolumab as third-line or later chemotherapy for unresectable/recurrent gastric cancer at our hospital from October 2017 to May 2020. RESULTS: The median follow-up was 5.9 months. The study included 45 men and 14 women (median age: 71 years). We observed that 7 patients had an Eastern Cooperative Oncology Group performance status of 0 and 52 patients had a performance status of 1-2. Forty-three patients were treated with third-line therapy, seven with fourth-line therapy, and three with fifth-line therapy. The response rate to nivolumab was 6.7% and disease control rate was 35.5%. There were 19 (32.2%) immune-related adverse events for all grades and 9 (15.2%) for grades 3 and 4. Progression-free survival was 1.90 months, and overall survival was 6.30 months. Patients with immune-related adverse events had significantly longer overall survival than those without immune-related adverse events. Multivariate analysis showed that the occurrence of immune-related adverse events and a ratio for neutrophil-to-lymphocyte ratio after 8 weeks of nivolumab treatment to the baseline neutrophil-to-lymphocyte ratio before treatment of ≤ 1.5 were independent prognostic factors for overall survival. CONCLUSIONS: Occurrence of immune-related adverse events and changes in neutrophil-to-lymphocyte ratio during nivolumab treatment may help predict the therapeutic efficacy of nivolumab monotherapy for unresectable or recurrent gastric cancer.