Preclinical Evaluation of an Anti-CD41 CAR T Cell in Acute Megakaryoblastic Leukemia on in Vitro and In Vivo Models

Acute Megakaryoblastic Leukemia (AMkL) is a rare disease that represents 5% of all reported AML cases and is diagnosed with high frequency in children with Down Syndrome and elderly people. M7-AMkL is characterized by a low overall survival and the patients have poor outcome to treatment, thus alternative treatments, such as CAR T cell therapies, are a need for better patient management.Herein, we present an evaluation of a new CAR T cell which targets CD41 marker, a specific surface antigen for M7-AMkL, in a preclinical model for AMkL using DAMI Luc2 cell line for in vitro and in vivo experiments. The performed flow cytometry evaluation showed that over 93% of the CAR T cells are eGFP positive, carrying the plasmid that permits CD41 targeting.The results highlight that the CAR T cells are inhibiting the AMkL cells with limited efficacy, with best inhibitory effect at lower effect: target ratios. The CAR T cells induced membrane damage to the targets, results sustained by the increased LDH activity, moreover TNF alpha levels were increased in the low E:T groups even after 24h. The in vivo evaluation indicates that the CAR T cells lowered the tumor size rapidly, but with limited efficacy due to the initiation of CRS.Our findings suggest that the anti CD41 CAR T cells are efficient for a limited time spawn and the better cytotoxic effect was visible in the low E:T ratio groups. However, further optimizations and evaluation are needed to improve the outcome of the anti CD41 CAR T cells.