Using multiple CRC cell lines with different KRAS mutation status and EGFR expression levels we found that reovirus directly enhanced NK cell cytotoxicity,and that, in combination with cetuximab, reovirus-activated NK cells exhibited increased CRC cell killing in vitro,regardless of KRAS mutation or EGFR expression.Then using human colorectal tumor xenograft models, we also observed that reovirus activation of NK cells, in conjunction with cetuximab, provided significantly greater anti-tumor effects than either monotherapy. The gene discussed is KRAS; the disease is colorectal neoplasm.