ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: One of the most common questions posed in CML practice is how to treat a patient of a particular age (from 15 to 90 years old) on frontline therapy with a particular TKI (e.g. imatinib, dasatinib, bosutinib, or nilotinib) and in whom the BCR::ABL1 transcripts (IS) are anywhere from 0.01 % to 0.5%.