In situ antigen modification-based target-redirected universal chimeric antigen receptor T (TRUE CAR-T) cell therapy in solid tumors

Chimeric antigen receptor (CAR)-T cell therapy has demonstrated remarkable success in the treatment of hematologic malignancies, while the success has not yet been replicated in solid tumors. To some extent, the disappointing results can be attributed to the paucity and heterogeneity of target antigens in solid tumors since adequate antigens are the cornerstone for CAR-T cells to recognize and attack tumor cells. We established a target-redirected universal CAR-T (TRUE CAR-T) cell therapeutic modality, in which exogenous antigens are loaded onto fusogenic nanoparticles to achieve in situ modification of cell membrane in solid tumors, providing targets for subsequent CAR-T cell therapy. The modification effect was evaluated by flow cytometry and confocal microscopic imaging. The in vivo metabolism and biodistribution of fusogenic antigen loaded nanoparticles (F-AgNPs) was explored using near infrared living imaging. Then F-AgNPs mediated in situ antigen modification were cooperated with corresponding CAR-T cell therapy, and its antitumor efficacy was evaluated using immune function experiments and further investigated in different tumor models. Using F-AgNPs, exogenous antigens were selectively modified onto tumor cell membranes through membrane fusion, spread deeper into tumor tissues through intercellular lipid transfer, further activating corresponding CAR-T cells and mediating antitumor immune responses towards multiple types of tumor cells, despite of their inherent antigen profiles. The cooperative treatment of F-AgNPs and CAR-T cell therapy successfully suppressed tumor proliferation and prolonged survival in both subcutaneous and peritoneally disseminated tumor models. The fusogenic nanoparticle-based in situ antigen modification overcome the limitation of target antigens paucity and heterogeneity in solid tumors, improving the efficacy and broadening the applications of CAR-T cells, thus establishing a novel TRUE CAR-T cell therapeutic modality with universal application and translational potential in immunotherapies for solid tumors.