The result revealed that the CDI risk score had close relationship with CD86 (r = 0.28; p = 7.0e − 11), PDCD1LG2 (r = 0.23; p = 1.4e − 07), CD48 (r = 0.21; p = 1.3e − 06), and PDCD1(r = -0.23; p = 1.4e − 07) (Fig. 7F), indicating CDI might have a nonnegligible role in the outcome prediction of ICB treatment in GBM. This evidence concerns the gene PDCD1LG2 and clostridium difficile infection.