ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Imatinib mesylate (IM, formerly known as CGP 57148B), the first approved selective tyrosine kinase inhibitor (TKI), is currently approved as standard care in patients with BCR‐ABL‐positive chronic myeloid leukemia (CML) and gastrointestinal stromal tumors (GIST) with impressive 6‐ and 8‐year survival rates of 88–95% 1, 2.