T cell cascade regulation initiates systemic antitumor immunity through living drug factory of anti-PD-1/IL-12 engineered probiotics

Immune checkpoint blockade (ICB) has revolutionized cancer therapy but only works in a subset of patients due to the insufficient infiltration, persistent exhaustion, and inactivation of T cells within a tumor. Herein, we develop an engineered probiotic (interleukin [IL]-12 nanoparticle Escherichia coli Nissle 1917 [INP-EcN]) acting as a living drug factory to biosynthesize anti-PD-1 and release IL-12 for initiating systemic antitumor immunity through T cell cascade regulation. Mechanistically, INP-EcN not only continuously biosynthesizes anti-PD-1 for relieving immunosuppression but also effectively cascade promote T cell activation, proliferation, and infiltration via responsive release of IL-12, thus reaching a sufficient activation threshold to ICB. Tumor targeting and colonization of INP-EcNs dramatically increase local drug accumulations, significantly inhibiting tumor growth and metastasis compared to commercial inhibitors. Furthermore, immune profiling reveals that anti-PD-1/IL-12 efficiently cascade promote antitumor effects in a CD8⁺ T cell-dependent manner, clarifying the immune interaction of ICB and cytokine activation. Ultimately, such engineered probiotics achieve a potential paradigm shift from T cell exhaustion to activation and show considerable promise for antitumor bio-immunotherapy.