Boarding Oncolytic Viruses onto Tumor-Homing Bacterium-Vessels for Augmented Cancer Immunotherapy

Oncolytic viruses (OVs) have been widely used as anticancer therapeutics because of their systemic immune responses during viral replication. However, the low enrichment of OVs within tumors and limited immune activation have hindered their clinical application. Herein, we proposed the concept of bacteria-assisted targeting of OVs to tumors, with liposome-cloaked oncolytic adenoviruses (OAs) conjugated onto tumor-homing Escherichia coli BL21 (designated as E. coli-lipo-OAs) for enhanced cancer immunotherapy. Notably, the enrichment of OAs transported by self-propelled bacterial microbe vehicles in E. coli-lipo-OAs in a nonsmall cell lung tumor can be potentiated by more than 170-fold compared with that of intravenously injected bare OAs. In vivo studies further revealed that E. coli-lipo-OAs administered intravenously significantly enhanced antitumor immunity through bacterial–viral-augmented immune responses. Our findings suggest that the self-driving microbe vehicle as a systemic delivery system for OVs can be a potent platform for developing future anticancer biotherapeutics at the clinical level.