ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Imatinib mesylate, a tyrosine kinase inhibitor (TKI), has revolutionized the treatment of chronic myeloid leukemia (CML) and gastrointestinal stromal tumors (GISTs) by targeting the BCR-ABL fusion protein and c-KIT mutations, respectively [1].