Patient specimens:CRC patients treated with PD-1 blockade therapy and measured F.nucleatum abundance in tumor tissues and feces.Cell: Human CRC cell lines DLD1 and Caco-2,mouse colon cancer cell line CT26.Mice: CT26.WT were implanted into the lateral wings of BALB/c mice, followed by intratumoral injection of F. nucleatum, Escherichia coli DH-5α or PBS,then injected anti-PD-L1 monoclonal antibody (mAb) or an isotype control mAb into the abdominal cavity. The gene discussed is PDCD1; the disease is malignant colon neoplasm.