In this study, we tested the hypothesis that reovirus infection would lead to innate and adaptive immune responses and sensitize MSS CRC to PD-1 therapy, by administering reovirus as a single agent or in combination with an anti-PD-1 monoclonal antibodies in various KRAS wild type (KRASWt) and mutant (KRASMut) CRC cell lines, and in syngeneic mouse models of CRC (14). Here, PDCD1 is linked to colorectal carcinoma.