Human CD45-PBD effectively targets and kills human HSCs and AML cells in vitro. (A-C) Cytotoxicity assays of CD45-ADC produced from anti-CD45 clone BC8 (biotinylated antibody plus SAv-drug conjugate), nb BC8 antibody plus free SAv-drug conjugate, or mouse IgG1-ADC (biotinylated isotype control antibody plus SAv-drug conjugate) against Jurkat cells (A), cord blood derived mononuclear cells (B), and patient-derived leukemia cells (C). Data points represent mean ± SEM of duplicate CFU plates (B) or triplicate wells (A,C) taken from 1 representative of at least 2 independent experiments. IC₅₀, 50% inhibitory concentration; ISO, isotype control; nb, nonbiotinylated.