Switching to nilotinib after suboptimal response or intolerance to imatinib in the TIDEL (Therapeutic Intensification in DE-novo Leukemia) II multicenter study in newly diagnosed patients with CML CP also demonstrated favorable results.52 In this ongoing study, patients are treated with high-dose imatinib (600 mg/d) and evaluated for imatinib intolerance or suboptimal response (as defined by BCR-ABL transcript levels of 10% at 3 months, 1% at 6 months, and 0.1% at 12 months by International Scale). Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.