BCR and chronic myelogenous leukemia, BCR-ABL1 positive: To test whether this mechanism is also operative in an independent BCR-ABL driven cell model and in primary human cells, we then investigated imatinib release upon HD-TKI pulse-exposure using different cell populations: Ba/F3-BCR-ABL cells as well as mononuclear cells from untreated CML patients and normal CD34+ hematopoietic progenitor cells from healthy donors exhibited the same kinetics as previously demonstrated for K562 cells (Figure 7A, panels II–IV).