The concept of targeted therapy emerged 20 years ago with the introduction of the Tyrosine Kinase Inhibitor (TKI) imatinib mesylate (IM), which targets the BCR:BCR:ABL1 oncoprotein [1] as a treatment for chronic myeloid leukemia (CML). Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.