Task: Question Answering
Input (English): Context: Since the initial approval of imatinib much has been learned about its resistance mechanisms, and efforts have continued to improve upon BCR-ABL tyrosine kinase inhibitor therapy. Targeted therapy with TKIs has continued to be an area of active research and development in the care of acute and chronic leukemia patients. This article reviews current approved and investigational TKI treatments for chronic myelogenous leukemia (CML), Philadelphia-chromosome positive acute lymphoblastic leukemia (Ph + ALL) and acute myelogenous leukemia (AML). There are now more potent BCR-ABL TKIs approved, which allow for additional options when determining front-line and second-line CML and Ph + ALL treatments. The T315I mutation is an ever-present challenge. Ponatinib, a pan BCR-ABL TKI, while still under investigation, is very hopeful with its ability to overcome T315I mutations in resistant CML and Ph + ALL patients. Because nilotinib and dasatinib have not been directly compared, at present we recommend selecting one or the other based on the side-effect profile, drug interactions, patient comorbidities, and mutational status. FLT-3 inhibition is of particular interest in AML patients with FLT-3 internal tandem duplication mutations; this type of targeted therapy continues to be studied. 
 Question: What tyrosine kinase, involved in a Philadelphia- chromosome positive chronic myelogenous leukemia, is the target of Imatinib (Gleevec)?
Output (English): bcr-abl