Even simply based on this parameter, it appears that approximately one third of CML patients do not show an optimal response to imatinib therapy and they are therefore facing a statistically significantly higher risk of an inferior outcome in terms of EFS, PFS, and also OS (approximately 80 % at 5 years with respect to >95 % of those below 10 % BCR-ABL at 3 months) [18, 22–24]. Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.