ASO Visual Abstract: Changes in the Gustave Roussy Immune Score as a Powerful Prognostic Marker of the Therapeutic Sensitivity of Nivolumab in Advanced Gastric Cancer: A Multicenter, Retrospective Study

Background Identification of positive biomarkers for the effects of nivolumab on patients with advanced gastric cancer (AGC) is significant. The Gustave Roussy Immune Score (GRIm-s) is associated with therapeutic resistance of immune checkpoint inhibitors (ICIs) in other cancers. This multicenter, retrospective study was designed to analyze the association of GRIm-s with therapeutic sensitivity of nivolumab in patients with AGC. Methods We reviewed 58 patients with AGC treated with nivolumab from October 2017 to November 2018 at five participating institutions. We performed blood tests before the start of nivolumab and after administration of two courses. We evaluated the correlation between the best overall response and GRIm-s. Additionally, we focused on the changes in GRIm-s before the start of nivolumab and after administration of two courses. Results Of the 58 patients, 21 (36.2%) were classified into the disease control (DC) group and 37 (63.8%) into the progressive disease (PD) group. GRIm-s before nivolumab treatment did not correlate with the best therapeutic response ( p = 0.086). However, GRIm-s after two courses of nivolumab showed that significantly more PD cases were in the high-risk group ( p < 0.0001). After two courses of nivolumab, overall survival was significantly worse in the high-risk group ( p < 0.0001). For progression-free survival, the high-risk group had a significantly worse prognosis both before ( p = 0.04) and after two courses of nivolumab treatment ( p < 0.0001). Conclusions GRIm-s after two courses of nivolumab and its changes compared to pretreatment values proved beneficial in predicting nivolumab sensitivity.