PDCD1 and colorectal carcinoma: Previous studies also indicated that decreased expression of IFNAR1 in human colorectal carcinoma tissues resulted in the suppression of the cytotoxic T lymphocytes function [33], and the combination of Peg-IFNα with PD-1 blockade dramatically enhanced T-cell infiltration and improved the efficacy of PD-1 antibody on hepatocellular carcinoma [34].