Transforming bacterial pathogens into wonder tools in cancer immunotherapy

Cancer immunotherapy has revolutionized cancer treatment due to its precise, target-specific approach compared with conventional therapies. However, treating solid tumors remains challenging as these tumors are inherently immunosuppressive, and their tumor microenvironment (TME) often limits therapeutic efficacy. Interestingly, certain bacterial species offer a promising alternative by exhibiting an innate ability to target and proliferate within tumor environments. Bacterial structural and functional components can activate innate and adaptive immune responses, creating tumor-suppressive conditions that reduce tumor mass. Additionally, bacteria can deliver effector molecules directly into tumor cells, inducing apoptotic and necrotic cell death. Despite their potential, the use of bacteria in cancer immunotherapy poses risks due to possible toxicities and unpredictable in vivo behavior. Advances in genetic engineering have addressed these concerns by enabling the development of attenuated bacterial strains with enhanced anticancer properties for safer medical applications. This review highlights the role of bacteria in TME modulation, recent strategies to bioengineer bacterial pathogens as therapeutic tools, and the synergistic effects of combining bacteria with other immunotherapies. It also discusses the challenges and prospects of translating this innovative approach into clinical practice, offering a comprehensive overview of bacteria-based cancer immunotherapy's potential to reshape the future of cancer treatment.