Engineering oncolytic bacteria as precision cancer therapeutics: design principles, therapeutic strategies, and...

Engineered oncolytic bacteria are emerging as a promising platform for precision cancer therapy, combining inherent tumor tropism, immunogenicity, and programmable gene control. Advances in synthetic biology now enable inducible and autonomous circuits that sense exogenous inputs (chemical signals or physical signals), bacterial self-cues (quorum sensing, bacterial invasion switches, or nitric oxide-responsive promoters), and tumor-specific pathophysiology (hypoxia, low pH, or lactate). These designs regulate colonization, lysis, and the spatiotemporally confined release of therapeutic cargos-including prodrug-converting enzymes, cytokines, and antibody/nanobody fragments-thereby enhancing antitumor efficacy while limiting off-target toxicity. Beyond monotherapy, oncolytic bacteria integrate with complementary modalities-including immune checkpoint blockade, adoptive cell therapies (CAR-T/NK), radiotherapy/chemotherapy, nanomedicine, and oncolytic viruses-to amplify immune activation and to enable multimodal, synergistic regimens. Concurrently, biosensor modules transform bacterial chassis into programmable "microbial factories" that couple therapy with real-time imaging and adaptive responses within the tumor microenvironment. This review synthesizes design principles for bacterial gene regulation, surveys recent preclinical advances, and highlights emerging combination strategies, while outlining translational considerations for safety, manufacturability, dosing, and patient selection. Together, these developments position engineered oncolytic bacteria as a promising route toward safe, effective, and ultimately personalized bacteria-based cancer therapeutics.