High-avidity cathepsin-G–specific CAR T cells for the treatment of acute myeloid leukemia

ABSTRACT: Chimeric antigen receptor (CAR) T cells specific for myeloid-associated antigens expressed on the cell surface of acute myeloid leukemia (AML) can cause depletion of normal myeloid progenitor cells. We developed a CAR specific for an HLA-A∗02:01-restricted peptide of the myeloid-restricted cathepsin-G (CG) protein. CG-specific CAR T cells (CG1.CAR) were further engineered to increase their functional avidity. Specifically, we developed CG1.CAR T cells coexpressing the lymphocyte-specific protein tyrosine kinase (LCK) and duplicated CD3ζ chain, which allows the functional recognition of the CG1 peptide as low as 0.025μM. Optimized CG1.CAR T cells displayed antileukemia effects in vitro and in vivo in patient-derived AML xenotransplant mouse models and did not cause hematopoietic toxicity in colony assays and humanized mice. Mechanistically, LCK overexpression in CG1.CAR T cells caused transcriptional modifications characterized by the overexpression of mitochondrial-encoded electron transport chain components that were correlated with increased mitochondrial mass and improved respiratory capacity. Based on these data, CG1.CAR T cells hold clinical potential for the treatment of AML.