While some studies have shown that primitive CML stem/progenitor cells are relatively resistant to killing by TKIs in vitro (Graham et al., 2002; Corbin et al., 2011), clinical studies suggest that long-term TKI therapy can decrement the CML stem cell compartment, at least in some patients (Etienne et al., 2017; Chen et al., 2019), consistent with mathematical modeling of patient BCR-ABL1 transcript data (Tang et al., 2011). Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.