Synthetic gene circuits in tumor immunotherapy: design principles and applications

Tumor immunotherapy has revolutionized cancer treatment by harnessing the immune system to recognize and eliminate malignant cells. However, limited response rates, systemic toxicity, and tumor heterogeneity remain major challenges. Synthetic gene circuits - engineered genetic programs capable of sensing, integrating, and responding to biological cues - offer a powerful strategy for developing next-generation 'smart' therapeutics. In this review, we summarize recent advances in synthetic gene circuits that enable smart and controllable tumor immunotherapy. We then discuss the design principles of these circuits, including small-molecule-inducible, physically responsive, and endogenous signal-responsive systems. Representative applications in tumor immunotherapy are highlighted, including programmable immune cells, microbial platforms, and tumor-intrinsic circuits that enable context-dependent activation, localized cytokine or effector release, and tumor-selective immunogenic cell death. Collectively, these advances illustrate the potential of synthetic gene circuits to improve specificity, safety, and therapeutic efficacy, paving the way for precision cancer immunotherapy and the next generation of cancer therapeutics.