Harnessing Living Therapies: The Role of CAR-T Cells, Oncolytic Viruses, and Bacteria in Cancer Treatment

Living therapies, including chimeric antigen receptor T (CAR-T) cells, oncolytic viruses (OVs), and bacteria-based platforms, are emerging as promising approaches in cancer treatment because they can directly target tumors and modulate anti-tumor immunity. This narrative review summarizes current knowledge on these therapies, focusing on their mechanisms of action, therapeutic applications, major limitations, and recent advances in genetic engineering, synthetic biology, and delivery systems. CAR-T cell therapy has shown substantial clinical success in hematological malignancies through the genetic redirection of T cells against tumor-associated antigens, although its efficacy in solid tumors remains limited by antigen heterogeneity and the immunosuppressive tumor microenvironment (TME). OVs selectively infect and lyse malignant cells while also stimulating local and systemic immune responses, and engineered OVs may further enhance therapeutic activity by reshaping the TME. Bacteria-based therapies exploit the natural tumor-targeting ability of selected strains, particularly in hypoxic regions, to deliver therapeutic agents and activate immune responses. Despite encouraging progress, safety concerns, immune-related barriers, and tumor complexity remain major challenges. Overall, integrating living therapies with modern biotechnological advances and existing treatment modalities may support more personalized and synergistic strategies for cancer management.