Clone C CAR T cells do not mediate toxicity toward healthy leukocytes, activated lymphocytes, or HSCs. (A) Flow cytometry of clone C or mIgG1 isotype binding of healthy A*02–positive CD3, CD19, CD33, and CD15 positive cells. Data are representative of 3 donors. (B) Lactate dehydrogenase–killing assay with clone C CAR T cells and magnetic-activated cell-sorted CD3, CD14, and CD19 positive cells. CD13 and CD19 positive cells were also tested after 48 hours of activation. BV173 cells served as positive control. (C) Zebra plot after coculture of clone C CAR T cells produced from cells of A*02–positive and –negative blood donors. Flow cytometry was performed after 18 hours’ coculture at 1:1 ratio. Plot is representative of 3 biological replicates. (D) Cell proliferation capacity of simulated but untransduced T cells and HLA-A*02–positive and –negative clone C CAR T cells. (E) Colony-forming unit (CFU) assays of cord blood–isolated CD34⁺ HSCs, OCI-AML02 cell line as positive control, and N3 primary AML cells. Cells were plated after 18-hour 1:1 coculture of CAR T cells and target cells. MUC16-specific 4H11 CAR T cells served as control. Error bars in panels B, D, and E denote standard deviation. *P < .05 (unpaired t test). APC-Cy7, allophycocyanin-cyanin 7; n.s., not significant; PE-A, phycoerythrin; Q, quadrant.