In 39% of newly diagnosed chronic-phase CML patients, therapy with a standard dose of imatinib for 12 months leads to a major molecular response comprising of 1000-fold reduction in BCR-ABL transcript levels, which is associated with a reduced risk of disease progression (Hughes et al, 2003). This evidence concerns the gene ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive.