Inhibition of the BCR-ABL tyrosine kinase activity by imatinib, the first generation of specific BCR-ABL inhibitors, results in durable cytogenetic and molecular remissions in the majority of CML and Ph+ ALL; however, not all patients benefit from treatment, due to drug resistance and intolerance [8], [9]. This evidence concerns the gene BCR and chronic myelogenous leukemia, BCR-ABL1 positive.