The PD-L1/PD1 axis is identified as an inhibitor of CTL activity in several CRC phenotypes including Mismatch repair deficiency (MMRd)/Microsatellite instability-high (MSI-H) phenotype in which anti-PD1 monoclonal antibodies are highly beneficial in fighting the tumor (10, 11). This evidence concerns the gene PDCD1 and neoplasm.