Synergically enhanced anti-tumor immunity of in vivo panCAR by circRNA vaccine boosting

Chimeric antigen receptor (CAR) T cell therapy has shown promise in treating hematologic malignancies, but it still faces challenges, including high costs, a time-consuming manufacturing process, and the necessity of lymphodepletion. Here, we generate circular RNAs (circRNAs) encoding CAR proteins, referred to as circRNA^CAR, which mediates remarkable tumor killing in human primary T cells. We demonstrate that circRNA^CAR, delivered with immunocyte-tropic lipid nanoparticles (LNPs), can form in vivo panCAR cells (CAR-T, CAR-natural killer [NK], and CAR-macrophage), significantly inhibit tumor growth, and reshape the tumor microenvironment in mice. Importantly, combining in vivo panCAR with circRNA-based vaccines encoding the corresponding HER2 antigens exhibits synergistically enhanced anti-tumor immunity. Notably, circRNA^CAR can in return boost the level of vaccination-elicited HER2-specific antibodies, mediating effective killing of tumor cells by macrophages. In combination with vaccination, in vivo panCAR demonstrates a synergistic enhancement of anti-tumor immunity across various mouse models, thereby establishing a framework for the synergistic in vivo panCAR-VAC immunotherapy.