ddC targets bulk and LSCs in vivo. (A-C) Three primary human AML cell samples were injected intrafemorally into irradiated female NOD/SCID mice. Mice were treated with 75 mg/kg per day of ddC by i.p. injection or vehicle control on day 11 for 3 weeks (n = 7 per group). Following treatment, human leukemia cell engraftment in the left femur was assessed by flow cytometry of human CD45⁺CD33⁺CD19⁻ cells. (D) Secondary engraftment was assessed by injecting viable leukemia cells from the bone marrow of ddC-treated and vehicle mice and injected into the right femur of irradiated female NOD/SCID mice, which remained untreated. Five weeks later, human leukemia cell engraftment in the left femur was measured by flow cytometry of human CD45⁺CD33⁺CD19⁻ cells. Line represents mean engraftment of human cells. For all experiments, *P < .05, **P < .01, ****P < .0001 using the Student t test.