Zinc-based radioenhancers to activate tumor radioimmunotherapy by PD-L1 and cGAS-STING pathway.

Radiotherapy and immunotherapy have already become the primary form of treatment for non-small-cell lung cancer (NSCLC), but are limited by high radiotherapy dose and low immune response rate. Herein, a multi-pronged strategy using a radio-immuno-enhancer (ZnO-Au@mSiO) is developed by inducing tumor cells apoptosis and reprograming the immunosuppressive tumor microenvironment (TME). The radio-immuno-enhancer employed Au as a radiosensitizer, transition Zn ions as immune activators, which not only tremendously enhances the anti-proliferative activity of radiotherapy toward cancer cells, but also activates the immune response with multi-targets to let "exhausted" T cells "back to life" by triggering immunogenic cell death (ICD), immune checkpoint blockade (ICB) that target PD-1/PD-L1 and cGAS-STING under X-ray irradiation with a low dosage. The in vivo results demonstrate desirable antitumor and immunogenic effects of radio-immuno-enhancer-mediated immune activation by increasing the ratio of cytotoxic T cells (CTLs) and helper T cells. This work provides a feasible approach for future development of effective transition metal ion-activated radio-immunotherapeutic agents.