Synthetic biology is being widely applied in tumor therapy, ranging from attenuating microbial toxicity to constructing synthetic gene circuits and developing CAR-T cells, all of which are reshaping the landscape of cancer immunotherapy. In this review, we summarize recent advances in microbial-based therapeutics that leverage bacteria’s natural tropism for hypoxic tumor regions to deliver immunomodulatory payloads with high spatial precision. Parallel progress in CAR-T cell engineering has led to the development of armored and logic-gated constructs designed to overcome challenges such as antigen heterogeneity, the immunosuppressive tumor microenvironment, and T cell exhaustion. Synthetic biology further integrates these platforms via programmable genetic circuits capable of performing Boolean logic operations, ensuring therapeutic activation only in the presence of tumor-specific biomarkers. While this convergence offers the unprecedented precision, safety, and potency in reprogramming anti-tumor immunity, the clinical translation of these complex systems faces significant hurdles. Despite challenges in clinical translation-including safety concerns, immune clearance, and manufacturing complexity-the field is advancing toward multifunctional “smart” therapies, synergistic microbial-cell combinations, and personalized treatment strategies. Together, these innovations are defining a new generation of precision-engineered immunotherapies with the potential to transform the treatment of refractory malignancies.

Melanoma remains highly lethal with frequent resistance to current therapies. Here we identify a marine-derived cyclopentapeptide, turnagainolide B, as a potent anti-melanoma agent that selectively kills B16-F10 melanoma cells (IC₅₀ = 50 μM) with low toxicity to normal skin cells. Using bioassay-guided isolation, we also obtained a new analogue, turnagainolide H, and elucidated their structures and biosynthetic pathways. Mechanistically, turnagainolide B induces a previously undescribed “dual-hit” autophagic signature: it simultaneously promotes autophagy initiation (via PI3K/mTOR suppression, evidenced by ATG5 and LC3B-II upregulation) and blocks autophagic degradation (evidenced by p62 accumulation). Co-treatment with chloroquine partially rescued cell viability and decreased LC3B levels, confirming that cell death depends on active autophagic flux disruption. Transcriptomic analysis, together with AI target prediction and docking, identified PI3K as a potential direct target, with downregulation of PI3K, mTOR, and BNIP3 supporting an imbalanced autophagic state. In a syngeneic mouse melanoma model, turnagainolide B significantly suppressed tumor growth, reduced melanin content and Ki67 expression, and enhanced CD8⁺ T cell infiltration. Collectively, this work expands the chemical diversity of the turnagainolide family, uncovers a unique “dual-hit” autophagic mechanism, and establishes turnagainolide B as a promising lead for melanoma therapy.