Enhancing CAR-T cell therapy against solid tumor by drug-free triboelectric immunotherapy

Chimeric antigen receptor (CAR) T cell therapy is a highly effective immunotherapy for hematological tumors, but its efficacy against most solid tumors remains challenging. Herein, a novel synergistic combination therapy of drug-free triboelectric immunotherapy and CAR-T cell therapy against solid tumor was proposed. A triboelectric nanogenerator (TENG) that can generate pulsed direct-current by coupling triboelectrification effect and electrostatic breakdown effect was fabricated. The TENG can generate up to 30 pulse direct-current peaks with peak current output approximate to 35 mu A in a single sliding to power the triboelectric immunotherapy. The pulsed direct-current stimulation induced immunogenic cell death of tumor cells (survival rate of 35.9 %), which promoted dendritic cells maturation, accelerated the process of antigen presentation to CAR-T cells and enhanced the systemic adaptive immune response. Furthermore, triboelectric immunotherapy promoted M1-like macrophage polarization, reduced regulatory T cells differentiation and reprogrammed the tumor immunosuppressive microenvironment, which ultimately enhanced the efficacy of CAR-T cells to eradicate nearly 60 % of NALM6 solid tumor mass. Notably, considering that triboelectric immunotherapy is a safe and effective drug-free antitumor strategy, the combined therapy did not increase the burden of double-medication on patients.