Gut microbial metabolite butyrate boosts p53-expressing telomerase-specific oncolytic adenovirus efficacy by enhancing infectivity and activating MHC-I/cGAS-STING.

The gut microbiota plays an essential role in regulating host immunity, and its metabolites such as butyrate exert immunomodulatory effects by acting as histone deacetylase inhibitors. Oncolytic virotherapy has emerged as a promising approach for cancer treatment, and we have developed OBP-702, a telomerase-specific oncolytic adenovirus that expresses p53 and elicits strong systemic antitumor responses. In this study, the potential synergy between butyrate and OBP-702 was investigated in colorectal cancer models. Using human and murine colorectal carcinoma cell lines, butyrate was found to directly enhance the infectivity of OBP-702 by upregulating CAR and integrins, thereby promoting apoptosis and autophagy in tumor cells. In addition, butyrate indirectly boosted systemic antitumor immunity by upregulating MHC-I expression through activation of the cGAS-STING pathway and enhancing CD8 + T cell recruitment via CXCL10 secretion. These findings were supported by in vivo experiments using CT26 subcutaneous, bilateral, and orthotopic tumor models, in which the combination of oral butyrate and intratumoral OBP-702 administration produced synergistic antitumor effects. These results highlight the therapeutic potential of integrating gut microbial metabolites with oncolytic virotherapy as a novel immunotherapeutic strategy for colorectal cancer.