J IMMUNOTHER CANCER

Background Chimeric antigen receptor (CAR)-T cells have emerged as a breakthrough treatment for relapse/refractory hematological tumors, showing impressive complete remission rates. However, around 50% of the patients relapse before 1-year post-treatment. T-cell 'fitness' is critical to prolong CAR-T persistence and activity. Allogeneic T cells from healthy donors are less dysfunctional or exhausted than autologous patient-derived T cells; in this context, Delta One T cells (DOTs), a recently described cellular product based on MHC/HLA-independent V delta 1(+)gamma delta T cells, represent a promising allogeneic platform. Methods Here we generated and preclinically validated, for the first time, 4-1BB-based CAR-DOTs directed against the interleukin-3 alpha chain receptor (CD123), a target antigen widely expressed on acute myeloid leukemia (AML) blasts. Results CD123CAR-DOTs showed vigorous, superior to control DOTs, cytotoxicity against AML cell lines and primary samples both in vitro and in vivo, even on tumor rechallenge. Conclusions Our results provide the proof-of-concept for a DOT-based next-generation allogeneic CAR-T therapy for AML.