The exosomes derived from CAR-T cell efficiently target mesothelin and reduce triple-negative breast cancer growth.

Genetically engineered T cells expressing a chimeric antigen receptor (CAR) have rapidly developed into a powerful and innovative therapeutic modality for cancer patients. However, the problem of dose-dependent systemic toxicity cannot be ignored. In this study, exosomes derived from mesothelin (MSLN)-targeted CAR-T cells were isolated, and we found that they maintain most characteristics of the parental T cells, including surface expression of the CARs and CD3. Furthermore, CAR-carrying exosomes significantly inhibited the growth of both endogenous and exogenous MSLN-positive triple-negative breast cancer (TNBC) cells. The expression of the effector molecules perforin and granzyme B may be a mechanism of tumor killing. More importantly, a highly effective tumor inhibition rate without obvious side effects was observed with the administration of CAR-T cell exosomes in vivo. Thus, the use of CAR-T cell exosomes has great therapeutic potential against MSLN-expressing TNBC.