CD34 and chronic myelogenous leukemia, BCR-ABL1 positive: While, in the absence of drug resistance, TKIs are effective against the majority of CD34+CD38+ and CD34+CD38− cells in CML patients 14, 15, more primitive LSCs are much less susceptible to the apoptosis induced by TKI treatment, with their persistence maintaining disease 16, 17, 18, 19.