A CAR T-inspiring platform based on antibody-engineered exosomes from antigen-feeding dendritic cells for precise solid tumor therapy.

Chimeric antigen receptor T (CAR T) cell therapy has achieved remarkable results treating patients with hematological malignancies in clinical studies. Although promising, extensive research has also revealed that CAR T therapy is unsatisfactory for the treatment of solid tumors. In addition, the production of CAR T cells is time-consuming and it's hard for storage and transportation. In this work, inspired by the construction of CAR T cell, we developed an antibody-engineered exosomes from antigen-feeding dendritic cells for beyond CAR T therapy of solid tumor by in situ T cells activation and cancer cell targeting. We have confirmed that tumor antigen-stimulated dendritic cell-derived exosomes (tDC-Exo) provided major histocompatibility (MHC)-antigen complexes and CD86 co-stimulating molecules, which were the same as CAR of CAR T cell acting as the necessary signals for T cell activation. Furthermore, anti-CD3 and anti-EGFR were then engineered on tDC-Exo to promote the binding of T cell to cancer cells for precise therapy. Our CAR T cell therapy-mimicking system have shown an efficient endogenous T cells activation and their crosslinking with cancer cells for enhanced solid tumor therapy. More interestingly, we found that immune activation significantly up-regulated PD-L1 expression, and thus we confirmed the combination with anti-PD-L1 antibodies further enhanced the efficacy of our CAR T cell therapy-mimicking platform.