Both-In-One Hybrid Bacteria Suppress the Tumor Metastasis and Relapse via Tandem-Amplifying Reactive Oxygen Species-Immunity Responses.

Bacterial therapy, which targets the tumor site and aims at exerting an antitumor immune response, has displayed a great potential against malignant tumors. However, failure of the phase I clinical trial of Salmonella strain VNP20009 alone demonstrates that bacterial treatment alone can unsatisfy the requirements of high efficiency and biosafety. Herein, a strategy of both-in-one hybrid bacteria is proposed, wherein the chemotherapeutic drug doxorubicin (DOX) is integrated onto the surface of glucose dehydrogenase (GDH)-overexpressed non-pathogenic Escherichia coli (E. coli) strain, to potentiate the antitumor efficacy. Nicotinamide adenine dinucleotide phosphate (NADPH), which is produced by GDH from E. coli, promotes the generation of toxic reactive oxygen species (ROS) within the tumor, and ROS is then catalyzed by the DOX-activated NADPH oxidases. Importantly, the hybrid bacteria enhance stimulated systemic antitumor immune responses, thereby leading to effective tumor eradication. When this strategy is applied in four different tumor models, the hybrid bacteria significantly inhibited tumor metastasis, postsurgical regrowth, and primary/distal tumor relapse. The both-in-one ROS-immunity-boosted hybrid bacteria strategy provides knowledge for the rational design of bacteria-based synergistic cancer therapy.