<i>In Situ</i> Delivery of Gasdermin E mRNA Promotes Antitumor Immunity via Creatine-Elicited Type I Interferon Signaling in Monocytes

Local immunotherapy stimulates immune responses against tumors while avoiding adverse effects associated with systemic administration. However, current strategies for tumor-targeted in situ immunotherapy are still limited. mRNA-based gene therapy represents a promising strategy. Gasdermin E (GSDME)-mediated pyroptosis is reported to exert antitumor immunity. In this study, we synthetized mRNA encoding GSDME encapsulated by lipid nanoparticles (LNP-Gsdme). In situ delivery of LNP-Gsdme through intratumoral injection suppressed tumor growth, boosted monocyte infiltration, and activated CD8+T cells. LNP-Gsdme induced immunogenic cell death in tumor cells, releasing creatine as a metabolic damage-associated molecular pattern. Creatine elicited the cGAMP-STING-type I IFN signaling pathway in monocytes and reprogrammed intratumoral monocytes toward an immunostimulatory phenotype, consequently potentiating CD8+ T cell-mediated antitumor immune responses. Furthermore, creatine supplementation enhanced the antitumor efficacy of LNP-Gsdme. Our study uncovers creatine as an important metabolic biomarker of pyroptosis-induced immunogenic cell death in tumors, providing new insights and a promising therapeutic approach for in vivo mRNA-based immunotherapies for cancer.