Cathepsin-G specific CAR-T cells for the treatment of Acute Myeloid Leukemia 2172

Abstract Description Targeting acute myeloid leukemia (AML) with chimeric antigen receptor (CAR)-T cells that recognize conventional myeloid-associated antigens expressed on the cell surface of blastic cells causes depletion of normal myeloid progenitor cells. Cathepsin-G (CG1) is a myeloid-restricted protein normally stored in azurophil granules but broadly expressed in the cytoplasm of leukemic blasts. In leukemic blasts, CG1 is processed, and the CG1-derived peptides are presented by the major histocompatibility complex and recognized by CD8 T cells. We developed a CAR that selectively targets an HLA-A2–restricted CG1 peptide in the CG1 peptide/HLA-A2 complex. Next, we enhanced the CAR to reach a functional avidity approximating that of a conventional alpha-beta T-cell receptor recognizing a peptide/HLA complex. Specifically, CAR-T cells with duplicated CD3ζ ITAM and overexpression of kinase LcK showed recognition of target cells presenting less than 0.025 uM of CG1 peptide. The enhanced CAR-T cells exhibited faster CD3ζ phosphorylation without significant modification of their molecular signature and a more robust metabolic profile than did conventional CAR-T cells. Furthermore, the enhanced CAR-T cells displayed significant antileukemia effects in vitro, in three independent AML PDX models, and in humanized mice without showing hematopoietic toxicity. Our findings demonstrate the clinical potential of CG1-specific CAR-T cells for the treatment of AML. Funding Sources The Leukemia and Lymphoma Society ID:6625-21 Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)