Abstract

Interleukin-12 (IL-12) potently stimulates antitumor immunity, but its clinical use is limited by systemic toxicity and poor spatial control. Here, we develop a dual-engineered delivery system that combines Escherichia coli Nissle 1917 (EcN) programmed for hypoxia- and quorum-sensing-regulated IL-12 expression with engineered dendritic cells (eDCs) that facilitate bacterial delivery and immune support. In murine colorectal cancer and liver metastasis models, eDC-EcN-IL12-QS preferentially localizes to tumors, increases intratumoral IL-12 and IFN- γ levels, enhances dendritic cell activation and CD8 + T cell infiltration, and suppresses tumor growth and metastatic burden. The system also prolongs survival and remains controllable by antibiotic-mediated clearance. These findings support a programmable microbial-cellular strategy for localized cytokine delivery and immune activation in immunologically cold tumors.