Task: Question Answering
Input (English): Context: Chronic myeloid leukemia (CML) is a clonal malignant myeloproliferative disorder characterized by the expansion of hematopoietic cells carrying the Philadelphia chromosome (t 9.22). Our main objective was to assess the efficacy of imatinib in CML patients, measured by their survival. Over a six-year period (June 2003 through May 2009), 25 patients were seen regularly for CML at the Lome Campus teaching hospital. Patients received imatinib after diagnosis and underwent regular laboratory monitoring (quantification of BCR-ABL ratio by RT-PCR). Patients' survival and treatment response were evaluated. Patients' mean age at diagnosis was 40 years (range: 9 to 72 years). Men predominated (17 compared with 7 women). Splenomegaly was found in 80% of cases. The mean leukocyte level was 188.71 g/L (24.4-350). Six patients (24%) had thrombocytosis with a mean platelet count of 491.15 g/L (108-2000). Six patients (24%) died after developing accelerated-phase CML or blast crisis. Estimated overall survival of patients at 6 years was 60%. Molecular biology monitoring detected a secondary G250E mutation with resistance to imatinib in one patient. Standard hematological side effects led to reduction in imatinib doses. The principal nonhematological side effects were weight gain and transient digestible disorders. At six years after diagnosis, imatinib was effective in treating patients with CML, even in sub-Saharan Africa. Mutation-induced resistance required regular molecular biological monitoring to determine the need to switch to later-generation tyrosine kinase inhibitors. 
 Question: What tyrosine kinase, involved in a Philadelphia- chromosome positive chronic myelogenous leukemia, is the target of Imatinib (Gleevec)?
Output (English): bcr-abl