A living enzymatic adenosine switch couples metabolic rescue to IL-12-driven antitumor immunity

Cancer cells remodel their metabolic environment to disable infiltrating immune cells. Adenosine is a principal mediator of this immunosuppression, impairing the metabolism and effector functions of T and natural killer (NK) cells. Blocking adenosine receptors or production within a redundant signaling network leaves the metabolite itself intact and has shown limited clinical efficacy. Adenosine deaminase (ADA) instead converts adenosine into inosine, a metabolite that can fuel T cell metabolism. We engineered non-pathogenic, tumor-tropic Escherichia coli K-12 DH5α to surface-display ADA, confining this metabolic switch to the tumor, and co-displayed interleukin-12 (IL-12) to couple metabolic rescue to local immune stimulation. Bacteria-displayed ADA alone restored metabolic and proliferative fitness in adenosine-suppressed lymphocytes to baseline, whereas incorporation of IL-12 coupled this rescue to enhanced effector function. Across multiple preclinical models of hematologic and solid malignancies, the dual-function bacteria were well tolerated, enhanced tumor control, prolonged survival, and induced durable protective immunity against melanoma rechallenge. The bacteria were enriched at tumor sites, reactivated quiescent immune compartments in leukemia, enhanced CAR-NK cell tumor trafficking and activity in pancreatic cancer, and outperformed recombinant proteins in breast cancer. These findings establish a modular living immunotherapeutic strategy that couples a local extracellular metabolic switch with localized cytokine delivery.