discovered that intratumoral injection of Fusobacterium nucleatum improved the effectiveness of PD-L1 blockade in colorectal cancer, a contradictory study revealed that succinic acid derived from F. nucleatum reduced sensitivity to anti-PD-1 antibody in colorectal cancer by impairing CD8+ T cell-mediated immunity.62 This evidence concerns the gene PDCD1 and colorectal cancer.