Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

One of the major mechanisms of communication between cells is the binding of polypeptide ligands to cell surface receptors possessing tyrosine kinase (TK) activity. Though many actions of these receptors involve physiological processes, perturbation of TK signaling can result in malignant transformation. During the last few decades, these signaling networks have been studied in detail and finally pharmacological agents targeted at key molecules could be produced. Though many agents have failed, some drugs like bevacizumab, trastuzumab, cetuximab, and erlotinib have already become part of the standard care for common tumors like breast, colorectal, lung, head and neck cancers. Furthermore, imatinib has shown unsurpassed efficacy in the less common, but not less problematic chronic myeloid leukemia and gastrointestinal stromal tumors. Multi-target agents like sunitinib, sorafenib, and lapatinib have already yielded promising results and new agents are being developed. The clinical successes of these agents are unquestionably based on the expanding body of knowledge on the molecular mechanisms that underlie the development and progression of a malignant phenotype. This review will focus on some of the most extensively studied signaling networks like Erb family of receptors, vascular endothelial growth factor (VEGF) and its receptor (VEGFR), Kit, platelet-derived growth factor receptor (PDGFR), and Ras.
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PMID:Molecular mechanisms of signal transduction: epidermal growth factor receptor family, vascular endothelial growth factor family, Kit, platelet-derived growth factor receptor, Ras. 1793 83

Imatinib inhibits tyrosine kinases important in osteoclast (c-Fms) and osteoblast (platelet-derived growth factor receptor [PDGF-R], c-Abl) function, suggesting that long-term therapy may alter bone homeostasis. To investigate this question, we measured the trabecular bone volume (TBV) in iliac crest bone biopsies taken from chronic myeloid leukemia (CML) patients at diagnosis and again after 2 to 4 years of imatinib therapy. Half the patients (8 of 17) showed a substantive increase in TBV (> 2-fold), after imatinib therapy, with the TBV in the posttreatment biopsy typically surpassing the normal upper limit for the patient's age group. Imatinib-treated patients exhibited reduced serum calcium and phosphate levels with hypophosphatemia evident in 53% (9 of 17) of patients. In vitro, imatinib suppressed osteoblast proliferation and stimulated osteogenic gene expression and mineralized-matrix production by inhibiting PDGF receptor function. In PDGF-stimulated cultures, imatinib dose-dependently inhibited activation of Akt and Crk-L. Using pharmacologic inhibitors, inhibition of PI3-kinase/Akt activation promoted mineral formation, suggesting a possible molecular mechanism for the imatinib-mediated increase in TBV in vivo. Further investigation is required to determine whether the increase in TBV associated with imatinib therapy may represent a novel therapeutic avenue for the treatment of diseases that are characterized by generalized bone loss.
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PMID:Long-term imatinib therapy promotes bone formation in CML patients. 1804 96

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. The name "GIST" was proposed in 1983, but the cell origin of GIST remained unclear until 1998, when my colleagues and I reported immunohistochemical evidence that GIST originated from interstitial cells of Cajal or their precursors. At the same time, we reported gain-of-function mutations of the Kit gene in GISTs. The Kit gene encodes KIT receptor tyrosine kinase, whose structure is similar to that of platelet-derived growth factor receptor (PDGFR). Imatinib mesylate was initially developed as an inhibitor of PDGFR. Then, it was found to be a potent inhibitor of BCR-ABL. Imatinib was successfully used for the treatment of chronic myeloid leukemia. When we reported gain-of-function mutations of the Kit gene in GISTs, the inhibitory effect of imatinib on KIT was already known. Imatinib was then successfully applied to the treatment of GISTs. The interrelationship between the type of Kit gain-of-function mutation and the therapeutic effect of imatinib has been well characterized in GISTs. Although various mutations of Kit and Pdgfr-alpha genes have been found in GISTs, most GISTs are luckily imatinibsensitive. After long-term administration of imatinib, however, new imatinib-resistant clones develop a secondary mutation of the Kit or Pdgfr-alpha gene. New drugs and adjuvant regimens against such secondary progression are now being intensively explored.
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PMID:Gastrointestinal stromal tumors: past, present, and future. 1864 36

Myeloproliferative disorders (MPD) are stem cell-derived clonal diseases arising as a consequence of acquired aberrations in c-ABL, Janus-activated kinase 2 (JAK2), and platelet-derived growth factor receptor (PDGFR) that generate oncogenic fusion tyrosine kinases (FTK), including BCR/ABL, TEL/ABL, TEL/JAK2, and TEL/PDGFbetaR. Here, we show that FTKs stimulate the formation of reactive oxygen species and DNA double-strand breaks (DSB) both in hematopoietic cell lines and in CD34(+) leukemic stem/progenitor cells from patients with chronic myelogenous leukemia (CML). Single-strand annealing (SSA) represents a relatively rare but very unfaithful DSB repair mechanism causing chromosomal aberrations. Using a specific reporter cassette integrated into genomic DNA, we found that BCR/ABL and other FTKs stimulated SSA activity. Imatinib-mediated inhibition of BCR/ABL abrogated this effect, implicating a kinase-dependent mechanism. Y253F, E255K, T315I, and H396P mutants of BCR/ABL that confer imatinib resistance also stimulated SSA. Increased expression of either nonmutated or mutated BCR/ABL kinase, as is typical of blast phase cells and very primitive chronic phase CML cells, was associated with higher SSA activity. BCR/ABL-mediated stimulation of SSA was accompanied by enhanced nuclear colocalization of RAD52 and ERCC1, which play a key role in the repair. Taken together, these findings suggest a role of FTKs in causing disease progression in MPDs by inducing chromosomal instability through the production of DSBs and stimulation of SSA repair.
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PMID:BCR/ABL and other kinases from chronic myeloproliferative disorders stimulate single-strand annealing, an unfaithful DNA double-strand break repair. 1875

The detailed molecular mechanism of action of second-generation BCR-ABL tyrosine kinase inhibitors, including perturbed targets and pathways, should contribute to rationalized therapy in chronic myeloid leukemia (CML) or in other affected diseases. Here, we characterized the target profile of the dual SRC/ABL inhibitor bosutinib employing a two-tiered approach using chemical proteomics to identify natural binders in whole cell lysates of primary CML and K562 cells in parallel to in vitro kinase assays against a large recombinant kinase panel. The combined strategy resulted in a global survey of bosutinib targets comprised of over 45 novel tyrosine and serine/threonine kinases. We have found clear differences in the target patterns of bosutinib in primary CML cells versus the K562 cell line. A comparison of bosutinib with dasatinib across the whole kinase panel revealed overlapping, but distinct, inhibition profiles. Common among those were the SRC, ABL and TEC family kinases. Bosutinib did not inhibit KIT or platelet-derived growth factor receptor, but prominently targeted the apoptosis-linked STE20 kinases. Although in vivo bosutinib is inactive against ABL T315I, we found this clinically important mutant to be enzymatically inhibited in the mid-nanomolar range. Finally, bosutinib is the first kinase inhibitor shown to target CAMK2G, recently implicated in myeloid leukemia cell proliferation.
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PMID:Global target profile of the kinase inhibitor bosutinib in primary chronic myeloid leukemia cells. 1903 22

Chronic myeloid leukemia (CML) is characterized by the presence of the Philadelphia chromosome (Ph), a genetic aberration that codes for bcrabl, which plays a key role in disease pathophysiology. The first oral inhibitor of Brc-Abl was imatinib, which also targets KIT and platelet-derived growth factor receptor kinase and has demonstrated improved outcomes when compared with interferon, the previous standard of care. Imatinib resistance and intolerance have been an issue for patients, and as a result, new therapeutic approaches have been evaluated. Dose-escalated imatinib (800 mg daily) has shown some limited activity in patients with imatinib-resistant CML, but the development of second-generation tyrosine kinase inhibitors has broadened the treatment options. Dasatinib is also an oral kinase inhibitor, but it has increased potency for Brc-Abl compared with imatinib. Dasatinib has demonstrated activity in all phases of CML and Ph+ acute lymphocytic leukemia and is approved for the treatment of adults in this setting. Recent phase III data have demonstrated that, in patients with chronic-phase CML, dasatinib 100 mg once daily is equally effective, with improved tolerability, compared with the previously approved 70-mg twice-daily dose. Nilotinib, which has been recently approved, has increased potency for Brc-Abl compared with imatinib and has demonstrated activity in patients with imatinib-resistant and -intolerant chronic- and accelerated-phase CML. As experience with these agents continues to mature, we might optimize the treatment efficacy and safety profiles by altering dose regimens.
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PMID:Optimizing treatment with Bcr-Abl tyrosine kinase inhibitors in Philadelphia chromosome-positive chronic myeloid leukemia: focus on dosing schedules. 1925 84

Hair depigmentation has been shown to occur with disruption of the interaction between the ligand stem cell factor (SCF) with its class III receptor tyrosine kinase c-kit, also called the stem cell factor receptor. This article reports the case of a patient who experienced depigmentation of her eyelashes, eyebrows, and temporal scalp hair six-to-eight weeks after initiating treatment with dasatinib (BMS-354825 or Sprycel), a novel dual Bcr-Abl/Src family tyrosine kinase inhibitor for chronic myeloid leukemia (CML). This case illustrates a previously unreported side-effect of dasatinib that is most likely due to the drug's inhibition of the c-kit, Src family, and platelet-derived growth factor receptor beta (PDGFRbeta) tyrosine kinases. Further study of hair depigmentation as a side effect of multi-kinase inhibitors can provide useful information on hair and melanocyte physiology.
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PMID:Hair depigmentation during chemotherapy with dasatinib, a dual Bcr-Abl/Src family tyrosine kinase inhibitor. 1936 59

Tyrosine kinase inhibitors have revolutionized the treatment of chronic myeloid leukemia (CML), offering patients several targeted therapeutic options that provide the possibility of sustained remissions and prolonged survival. With the availability of imatinib, nilotinib and dasatinib, physicians must weigh the efficacy and safety profile of each agent when choosing the best therapeutic option for individual patients. Each agent targets tyrosine kinases within the cell uniquely to cause the desired antiproliferative effect. In addition to inhibiting the BCR-ABL kinase, imatinib and nilotinib target the same array of other tyrosine kinases, including c-KIT and platelet-derived growth factor receptor (PDGFR), albeit with differing potencies. While targeting BCR-ABL with the highest potency among approved agents in CML, dasatinib also targets a broad array of off-target kinases, including SRC family members, PDGFR and EPHB4. The differences in kinase inhibition profiles among these agents in vitro probably account for the differing clinical safety profiles of these agents. This paper reviews the various kinases inhibited by imatinib, nilotinib and dasatinib, and describes the potential impact of kinase inhibition on the efficacy and safety of each agent.
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PMID:Class effects of tyrosine kinase inhibitors in the treatment of chronic myeloid leukemia. 1947

Dasatinib is an oral potent adenosine triphosphate (ATP)-competitive inhibitor of BCR-ABL, cKIT, platelet-derived growth factor receptor, and SRC family kinases (SFKs), which has demonstrated high efficiency in patients with imatinib-resistant chronic myelogenous leukemia. Here, we show that dasatinib weakly affects platelet activation by thrombin or adenosine diphosphate but is a potent inhibitor of platelet signaling and functions initiated by collagen or FcgammaRIIA cross-linking, which require immunoreceptor tyrosine-based activation motif phosphorylation by SFKs. Accordingly, dasatinib treatment rapidly decreases the volume of thrombi formed under arterial flow conditions in whole blood from patients or mice perfused over a matrix of collagen. Moreover, treatment of mice with dasatinib increases the tail bleeding time in a dose-dependent manner. Interestingly, these effects are rapidly reversible after interruption of the treatment. Our data clearly demonstrate that, in contrast to imatinib, dasatinib affects platelet functions in vitro and in vivo, which has important implications in clinic and could explain increased risks of bleeding observed in patients. Moreover, dasatinib efficiently prevents platelet activation mediated by FcgammaRIIA cross-linking and by sera from patients with heparin-induced thrombocytopenia, suggesting that reversible antiplatelet agents acting as ATP-competitive inhibitors of SFKs may be of therapeutic interest in the treatment of this pathology.
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PMID:The new tyrosine-kinase inhibitor and anticancer drug dasatinib reversibly affects platelet activation in vitro and in vivo. 1971 76

Dasatinib, an oral inhibitor of multiple tyrosine kinases, including BCR-ABL, Src, and platelet-derived growth factor receptor, was approved for patients with imatinib-resistant or -intolerant chronic myeloid leukemia (CML) or Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL). Dasatinib demonstrated efficacy with a well-tolerated safety profile in all phases of CML and Ph+ ALL, which led to its 2006 approval by the U.S. Food and Drug Administration for clinical use. However, although most adverse events are grade 1 or 2, a number of adverse events require management and monitoring to ensure that patients can continue receiving the treatment. This review discusses the appropriate nursing management of key adverse events (cytopenias, fluid retention, bleeding, gastrointestinal toxicity, and cardiotoxicity) to ensure that patients gain maximum benefit from this multitargeted agent.
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PMID:Practical management of dasatinib for maximum patient benefit. 1950 92


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