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Bcr-Abl Tyrosine Kinase Inhibitors (bcr-abl tyrosine + kinase_inhibitor)

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Medical Sciences100%

Selected Abstracts

Overproduction of BCR-ABL induces apoptosis in imatinib mesylate-resistant cell lines

CANCER, Issue 1 2005
Vanessa Desplat Ph.D.
Abstract BACKGROUND Imatinib mesylate, a BCR-ABL tyrosine kinase inhibitor, induces apoptosis in chronic myeloid leukemia cells. Resistance to imatinib is currently the most important concern of this treatment. One of the main mechanisms of this resistance is overexpression of BCR-ABL. METHODS In the current study, the authors investigated the correlation between BCR-ABL overexpression and apoptosis in BaF/BCR - ABL and LAMA84 cell lines resistant to imatinib suddenly deprived of the inhibitor, and compared with their sensitive counterpart. RESULTS Removal of imatinib from culture medium led to a decrease in Bcr-Abl protein expression by Day 5, which was sustained for , 3 weeks of imatinib deprivation. Apoptosis was observed after 3 days of imatinib deprivation in resistant lines accompanied by caspase activation, loss of membrane asymmetry (annexin V staining), and alteration of mitochondrial potential (dihexyloxacarbocyanine iodide [DiOC6]). Transient activation of the STAT5/Bcl-xL pathway and Akt kinase activity preceded these responses. CONCLUSIONS Thus, imatinib removal led to apoptosis of BCR-ABL,overexpressing leukemic cells, a phenomenon that could be exploited to sensitize imatinib-resistant cells to the cytotoxic effect of other drugs. Cancer 2005. © 2004 American Cancer Society. [source]

Novel agents to override imatinib resistance mechanisms

DRUG DEVELOPMENT RESEARCH, Issue 7 2008
Asumi Yokota
Abstract Chronic myelogenous leukemia (CML) is a disorder of hematopoietic stem cells that results from the Philadelphia chromosome (Ph) created through translocation of human chromosomes 9 and 22. The resulting Bcr-Abl fusion protein has constitutively high tyrosine kinase activity that causes transformation of hematopoietic stem cells. Imatinib mesylate (IM) was developed as a specific Bcr-Abl kinase inhibitor and is efficacious in treating Ph-chromosome-positive (Ph+) leukemias such as CML and Ph+ acute lymphoblastic leukemia (ALL). Within a few years of its introduction to the clinic, IM has dramatically altered the first-line therapy for CML. Although most newly diagnosed CML patients in the chronic phase (CP) achieved durable responses when treated with IM, resistance to IM has become a major problem in patients with advanced-stage disease. The most important mechanism of IM resistance are point mutations within the Abl kinase domain; therefore, there is an urgent need for novel agents that can inhibit mutated Bcr-Abl. In this review, we describe novel Bcr-Abl tyrosine kinase inhibitors, the so-called "Super Gleevec" inhibitors. Drug Dev Res 69:398,406, 2008. © 2008 Wiley-Liss, Inc. [source]

First-line therapy for chronic myeloid leukemia: Past, present, and future,

AMERICAN JOURNAL OF HEMATOLOGY, Issue 5 2009
Carolina Pavlovsky
The development of Bcr-Abl tyrosine kinase inhibitors has dramatically changed the prognosis of patients with newly diagnosed chronic myeloid leukemia (CML). Standard-dose imatinib (400 mg/day in chronic phase, 600 mg/day in advanced CML) now dominates the management of this disease, producing considerably higher hematologic, cytogenetic, and molecular response rates than seen with previous drug therapies. However, although many patients respond well to standard-dose imatinib initially, some patients do not achieve adequate levels of response or discontinue therapy because of resistance. One approach to improving treatment response with first-line imatinib may be to increase the imatinib dose (800 mg/day), although recent trial data indicate that overall increases in response rates may be modest. Newer Bcr-Abl tyrosine kinase inhibitors can induce responses in patients with all phases of imatinib-resistant CML, even those with imatinib-resistant mutations in the BCR-ABL gene. Furthermore, in initial studies, first-line dasatinib or nilotinib treatment has produced response rates that compare favorably with historical controls treated with imatinib, although confirmation is required from head-to-head clinical trials. Future clinical approaches may include drug combinations, which may allow quiescent leukemia stem cells to be eradicated. Further improvements in drug treatment for first-line CML are expected during the next few years. Am. J. Hematol. 2009. © 2009 Wiley-Liss, Inc. [source]