TDZD-8 ablates leukemia progenitor and stem cells. (A) Primary AML (n = 10), ALL (n = 3), bcCML (n = 3), and normal specimens (n = 7, obtained from BM, CB, or MPB specimens) were cultured for 18 to 24 hours in the presence or absence of 20 μM TDZD-8. Cell viability was assessed by flow cytometry in CD34⁺CD38⁻ populations for AML and bcCML (CML) and CD34⁺CD10⁻ cells for ALL using Annexin V/7-AAD stain. Percent viability is represented relative to untreated control. Specificity to leukemia specimens was significant (**P < .01). Error bars represent the SEM. (B) Primary cells from AML (n = 11), bcCML (CML; n = 3), and normal specimens (n = 12) were treated for 18 hours in suspension culture, followed by plating in methylcellulose. Error bars represent the SEM. Percentage of colony-forming units (CFUs) are normalized to untreated controls. All assays were performed in triplicate. Specificity to leukemia specimens was significant (**P < .01, *P < .05). (C) Percentage of marrow engraftment for NOD/SCID mice that received a transplant with AML (top panels) or normal CB (bottom panels) cells after 18 hours of culture with or without 20 μM TDZD-8. Each circle or triangle represents a single animal analyzed at 6 weeks after transplantation. Each plot represents an independent AML or CB specimen. Mean engraftment is indicated by the horizontal bars. **P < .01; ***P < .001.