Dasatinib in Imatinib-Resistant Philadelphia Chromosome–Positive Leukemias

The BCR-ABL tyrosine kinase inhibitor imatinib is effective in Philadelphia chromosome–positive (Ph-positive) leukemias, but relapse occurs, mainly as a result of the outgrowth of leukemic subclones with imatinib-resistant BCR-ABL mutations. We evaluated dasatinib, a BCR-ABL inhibitor that targets most imatinib-resistant BCR-ABL mutations, in patients with chronic myelogenous leukemia (CML) or Ph-positive acute lymphoblastic leukemia (ALL).