Due to the lack of genetic complexity when compared with other types of leukaemia, and its well-defined leukaemic stem cell (LSC) population (enriched for with CD34+CD38−), chronic phase CML is a paradigm for targeted therapy and thus a model disease to examine how LSCs respond to anti-cancer treatments. This evidence concerns the gene CD38 and chronic myelogenous leukemia, BCR-ABL1 positive.