Here, we demonstrated that DS, particularly when co-administrated with non-toxic concentrations of Cu (e.g., 1 μM), was highly cytotoxic to leukemia stem-like cells, including CD34+/CD38− KG1α cells and CD34+/CD38− Kasumi-1, as well as primary CD34+ cells isolated from AML patients, in a dose-dependent manner, whereas largely sparing normal hematopoietic progenitor cells. The gene discussed is CD38; the disease is leukemia.