IL3-zetakine combined with a CD33 costimulatory receptor as a Dual CAR approach for safer and selective targeting of AML

: Acute Myeloid Leukemia (AML) still represents an unmet clinical need for adult and pediatric patients. Adoptive cell therapy by chimeric antigen receptor (CAR)-engineered T cells demonstrated a high therapeutic potential, but further development is required to ensure a safe and durable disease remission in AML, especially in elderly patients. To date, translation of CAR T cell therapy in AML is limited by the absence of an ideal tumor-specific antigen. CD123 and CD33 are the two most widely overexpressed LSCs biomarkers but their shared expression with endothelial and hematopoietic stem and progenitor cells (HSPCs) increases the risk of undesired vascular and hematologic toxicities. To counteract this issue, we established a balanced Dual CAR strategy aimed at reducing off-target toxicities while retaining full functionality against AML. Cytokine-Induced Killer (CIK) cells, co-expressing a first-generation low affinity anti-CD123 IL3-zetakine and an anti-CD33 as costimulatory receptor (CCR) without activation signaling domains, demonstrated a powerful antitumor efficacy against AML targets without any relevant toxicity on HSPCs and endothelial cells. The proposed optimized Dual CAR CIK strategy could offer the opportunity to unleash the potential of specifically target CD123+/CD33+ leukemic cells while minimizing toxicity against healthy cells.