Imatinib was the first BCR-ABL TKI to obtain clinical approval from the US Food and Drug Administration (FDA) for the treatment of Philadelphia chromosome–positive (Ph+) CML (Druker et al., 2001, 2006; Novartis Pharmaceuticals, 2014a), and several newer BCR-ABL TKIs have been approved in recent years. The gene discussed is ABL1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.