While established immunotherapy-related biomarkers like programmed death ligand 1 (PD-L1) expression, tumor mutational burden (TMB), microsatellite instability (MSI), and DNA mismatch repair (MMR) are used to predict immunotherapy efficacy in various malignancies, the precise impact of immune-related genes (IRGs) on the tumor immune microenvironment and the underlying molecular mechanisms in GC remain poorly understood. Here, CD274 is linked to gastric cancer.