An immune checkpoint-based score is a prognostic marker in retrospective cohort study of patients with gastric cancer.

Background: Immunotherapy has emerged as an effective treatment for many cancers. However, only a proportion of gastric cancer (GC) patients can benefit from immunotherapy. Thus, assessing different immune checkpoints, which regulate T-cell activation and function, is critical. This study aimed to explore the role of the six immune checkpoints, including B7-H3, B7-H4, PD-L1, PD-1, VISTA, and TIGIT, in GC. Methods: The expression patterns of the six immune checkpoints in 478 GC patients were evaluated by immunohistochemistry. The relationships between immune checkpoints, clinicopathological features, and overall survival (OS) were analyzed. Results: The positivity rates for B7-H3 in tumor cells (TCs) and stromal cells (SCs), B7-H4 in TCs, PD-L1 in TCs and SCs, PD-1 in immune cells (ICs), VISTA in ICs, and TIGIT in ICs were 36.2%, 63.2%, 2.3%, 16.7%, 25.1%, 59.0%, 37.4%, and 30.5%, respectively. Except for B7-H4, other immune markers were positively correlated with each other. An immune score (IS) based on the expression of four prognostic markers (B7-H3, PD-L1, VISTA, and TIGIT), was devised. Patients were classified as high-IS (40.8%) and low-IS (59.2%). The multivariate analysis showed IS to be an independent prognostic biomarker for OS (hazard ratio: 2.212, 95% confidence interval: 1.597-3.063, P<0.001). Conclusions: This study identified different expression patterns of six immune checkpoints in GC, and IS based on the expression of four markers, could serve independently as a predictor of OS in GC, which might provide potential immune targets for GC patients.