Chimeric Antigen Receptor-T Cells Derived Extracellular Vesicles as a Potential Cancer Therapy

CAR-T cells are genetically engineered T cells, directed against a tumor-associated antigen. While CAR-T cell therapy shows great promise in hematological malignancies, its implication for solid tumors is far more difficult. This difficulty rise from the hostile tumor microenvironment and lack of tumor penetration. Extracellular vesicles (EVs) are cell-derived membranous vesicles varies in size and point of origin. Taking advantage of both their small size and the content similarity to the parental cells, EVs may escape the immunosuppressive microenvironment of the solid tumor, penetrate it and act as a surrogate CAR T cell. In order to mimic the CAR-T cell activity EVs were isolated from media of CAR-T cells stimulated with the specific antigen against which the CAR is directed. These EVs were characterized for their content and functions. EVs isolated from stimulated CAR-T cells exhibit similar content to their parental cells. Both several cytokines and granzyme B were found to be higher when compared with EVs isolated from unstimulated CAR-T cells. We show that anti-HER-2 CAR-T EVs bounded and penetrated specifically into HER-2 expressing target cells. Furthermore, co-cultured target cells with either CAR-T cells or CAR T EVs isolated from stimulated CAR-T cells exhibited elevated levels of caspase 3/7 activity. However, while the CAR-T cells induced massive apoptosis during the first 24h, CAR-T EVs required 60 − 90 h. a mouse model is being calibrated to assess the EVs ability in vivo. In summary, CAR-T EVs provide a novel potent immunotherapy approach that may be effective against solid tumors.