An optimal early response to TKI therapy is an important determinant for long-term outcome in CML [52, 53], as the values of BCR::ABL1 transcripts and the kinetics of their descent in the first trimester (also commonly referred to as halving time) are predictive of deep MR thereafter [54–56]. Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.