The Abl tyrosine kinase inhibitor imatinib (CGP 57148B/STI571) was first introduced in 1996, tested in the clinic from 1998 and approved for treating BCR-ABL-positive CML, Philadelphia chromosome-positive acute lymphoblastic leukemia and gastrointestinal stroma tumor [12–15]. This evidence concerns the gene ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive.