Muc1-Tn-Targeting Chimeric Antigen Receptor-Modified V Gamma 9v Delta 2 T Cells With Enhanced Antigen-Specific Anti-Tumor Activity

Chimeric antigen receptor (CAR) alpha beta T cell adoptive immunotherapy has shown great promise for improving cancer treatment. However, there are several hurdles to overcome for the wide clinical application of CAR-alpha beta T cells therapy, including side effects and a limited T cells source from cancer patients. Therefore, we sought to identify an alternative T cell subset that could avoid these limitations and improve the effectiveness of CAR-T immunotherapy. gamma delta T cells are a minor subset of T cells, which share the characteristic of innate immune cells and adaptive immune cells. V gamma 9V delta 2 T cells are a predominant gamma delta T subset in the circulating peripheral blood. In this study, we investigated the antigen-specific antitumor activity of CAR-V gamma 9V delta 2 T cells targeting MUC1-Tn antigen. V gamma 9V delta 2 T cells were expanded from peripheral blood mononuclear cells of healthy volunteers with zoledronic acid and interleukin-2. CAR-V gamma 9V delta 2 T cells were generated by transfection of lentivirus encoding MUC1-Tn CAR. Cytotoxicity assays with various cancer cell lines revealed that CAR-V gamma 9V delta 2 T cells could effectively lyse tumor cells in an antigen-specific manner, with similar or stronger effects than CAR-alpha beta T cells. However, CAR-V gamma 9V delta 2 T cells had shorter persistence, which could be improved with the addition of IL-2 to maintain the function of CAR-V gamma 9V delta 2 T cells with consecutive stimulation of tumor cells. Using a xenograft mouse model, we further showed that CAR-V gamma 9V delta 2 T cells more effectively suppressed tumor growth in vivo than V gamma 9V delta 2 T cells. Therefore, MUC1-Tn CAR-modified V gamma 9V delta 2 T cells may represent a novel, promising ready-to-use product for cancer allogeneic immunotherapy.