Dasatinib has shown efficacy in a series of multicenter, open-label Phase II clinical studies with patients in all phases of CML or with Ph+ ALL who are resistant to or intolerant of imatinib (the START [SRC/Abl Tyrosine kinase inhibition Activity: Research Trials of dasatinib] program). The gene discussed is ABL1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.