CD8A and neoplasm: F. nucleatum may modulate immune checkpoint therapy for CRC via activation of STING pathway.Therapeutic responses of PD-1 blockade were positively associated with the level of F. nucleatum in CRC.F. nucleatum induced PD-L1 expression by activating STING signaling and increased the accumulation of IFNγ+CD8+ TILs during treatment with PD-L1 blockade, thereby enhancing anti-tumor effect and therapeutic responses of PD-L1 blockade in mice and prolonged survival. The therapeutic response of PD-L1 blockade in CRC organoids was improved by F. nucleatum.