Tyrosine kinase inhibitors (TKIs) that block the activity of the BCR-ABL1 gene fusion product, the hallmark of chronic myeloid leukemia (CML), have substantially improved efficacy and tolerability of treatment and extended patient life expectancy to nearly that of the general population [1]. The gene discussed is ABL1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.