To reduce the cytotoxic effects of oncolytic viral therapy on normal host tissues or cells, we investigated the cytotoxic effects on three p53-deficient colorectal cancer cell line, including HT29, SW480, and SW620 [33], through the combination of prodrug activation and MSC-delivered CRAdNTR both in vitro and in vivo. The gene discussed is TP53; the disease is colorectal cancer.