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)

Imatinib mesylate (IM), is a selective and competitive inhibitor of tyrosine kinases, including BCR-ABL, ABL, KIT, and the platelet-derived growth factor receptors (PDGF-R). It binds to the ATP-binding site of the target kinase and prevents the transfer of phosphate from ATP to the tyrosine residues of various substrates. At oral doses of 200-600 mg, the majority of patients with chronic myeloid leukaemia, Philadelphia chromosome-positive acute lymphoblastic leukemia expressing the BCR-ABL fusion protein and gastrointestinal stromal tumours (GIST) achieve a bio-molecular and clinical response, frequently complete, associated with limited toxicity. Several other human cancers, as small-cell lung carcinoma, melanoma, seminoma, some sarcomas, and adenoid cystic carcinomas may over-express KIT or PDGF-R, and clinical trials to evaluate the role of IM in the treatment of such cancers are currently ongoing. We determined c-KIT with Dako CD 117 antibody in 5 cases of advanced ocular melanoma (OM) and we found positive immuno-reactivity for CD 117 in three patients. We treated all patients with palliative-use IM at the oral dose of 400 mgr daily. We obtained in expressing positive immuno-reactivity for CD 117 patients: a reduction of malignant ascites in one, a partial remission in the neck nodes in another, and progression of liver metastases in the third. Evidences of progression has been reported in the other two patients expressing negative immuno-reactivity for CD 117. We conclude that the effect of IM should be assessed only in OM with positive immuno-histochemical c-kit (CD 117) expression. IM might be a potential therapeutic strategy for these patients.
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PMID:Tyrosine kinase inhibitor imatinib mesylate as anticancer agent for advanced ocular melanoma expressing immunoistochemical C-KIT (CD 117): preliminary results of a compassionate use clinical trial. 1676

Philadelphia (Ph) chromosome is the cytogenetic hallmark of chronic myeloid leukemia (CML). The translocation forms a chimeric gene, bcr-abl, which generates BCR-ABL. This fusion protein constitutively activate ABL tyrosine kinase and causes CML. Imatinib mesylate is a selective tyrosine kinase inhibitor on ABL, c-Kit and PGDF-receptor, and functions through competitive inhibition at the ATP-binding site of the enzyme, which leads to growth arrest or apoptosis in cells that express BCR-ABL. Imatinib has revolutionized the management of patients with CML, and at a dose of 400 mg daily has become the current standard therapy for newly diagnosed patients with CML even when they have HLA-matched family donors. Although imatinib therapy has only a 5-year history, it is hoped that CML will be cured with this drug and with forthcoming second-generation tyrosine kinase inhibitors as well as by allogeneic stem cell transplantation in patients who have become resistant to these drugs.
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PMID:Treatment of chronic myeloid leukemia with imatinib mesylate. 1685 Jan 23

Imatinib mesylate (Gleevec) is a small-molecule inhibitor of the fusion protein Bcr-Abl, the causal agent in chronic myelogenous leukemia. Here we report ten individuals who developed severe congestive heart failure while on imatinib and we show that imatinib-treated mice develop left ventricular contractile dysfunction. Transmission electron micrographs from humans and mice treated with imatinib show mitochondrial abnormalities and accumulation of membrane whorls in both vacuoles and the sarco- (endo-) plasmic reticulum, findings suggestive of a toxic myopathy. With imatinib treatment, cardiomyocytes in culture show activation of the endoplasmic reticulum (ER) stress response, collapse of the mitochondrial membrane potential, release of cytochrome c into the cytosol, reduction in cellular ATP content and cell death. Retroviral gene transfer of an imatinib-resistant mutant of c-Abl, alleviation of ER stress or inhibition of Jun amino-terminal kinases, which are activated as a consequence of ER stress, largely rescues cardiomyocytes from imatinib-induced death. Thus, cardiotoxicity is an unanticipated side effect of inhibition of c-Abl by imatinib.
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PMID:Cardiotoxicity of the cancer therapeutic agent imatinib mesylate. 1720 21

Imatinib mesylate, Abl tyrosine kinase inhibitor, has improved the treatment of Bcr-Abl-positive leukemia such as chronic myeloid leukemia (CML) and Philadelphia chromosome positive acute lymphoblastic leukemia (Ph(+)ALL). However, resistance is often reported in patients with advanced-stage disease. Several novel tyrosine kinase inhibitors, which have been developed to override imatinib resistance mechanisms such as overexpression of Bcr-Abl and point mutations within the Abl kinase domain, are currently competing. Inhibitors of Abl tyrosine kinase are divided into two main groups, namely, ATP-competitive and ATP non-competitive inhibitors. Moreover, ATP-competitive inhibitors are fall into two subclasses, i.e. the Src/Abl inhibitors, and 2-phenylaminopyrimidin-based compounds. Dasatinib (formerly BMS-354825), AP23464, SKI-606 and PD166326 are classified as Src/Abl inhibitors while AMN107 and NS-187 (INNO-406) belong to the latter subclass of inhibitors. Among these agents, clinical studies on dasatinib and AMN107 had started earlier than the others and favorable results are accumulating. Clinical studies of other compounds including NS-187 (INNO-406) will be performed in rapid succession. Because of its strong affinity, most ATP competitive inhibitors may be effective against imatinib-resistant patients. However, to date, an ATP-competitive inhibitor that can inhibit the phosphorylation of T315I Bcr-Abl has not yet been developed. To address this problem, ATP non-competitive inhibitors such as ON012380, Aurora kinase inhibitor VX-680 and p38 MAP kinase inhibitor BIRB-796 have been developed. It may be necessary for the improvement of CML and Ph(+)ALL treatment to be taken into consideration of the combination therapy with novel ATP-competitive inhibitors and these agents.
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PMID:New tyrosine kinase inhibitors in the treatment of chronic myeloid leukemia. 1707 52

Human myeloid leukemias provide models of maturation arrest and differentiation therapy of cancer. The genetic lesions of leukemia result in a block of differentiation (maturation arrest) that allows myeloid leukemic cells to continue to proliferate and/or prevents the terminal differentiation and apoptosis seen in normal white blood cells. In chronic myeloid leukemia, the bcr-abl (t9/22) translocation produces a fusion product that is an activated tyrosine kinase resulting in constitutive activation cells at the myelocyte level. This activation may be inhibited by imatinib mesylate (Gleevec, STI-571), which blocks the binding of ATP to the activated tyrosine kinase, prevents phosphorylation, and allows the leukemic cells to differentiate and undergo apoptosis. In acute promyelocytic leukemia, fusion of the retinoic acid receptor-alpha with the gene coding for promyelocytic protein, the PML-RAR alpha (t15:17) translocation, produces a fusion product that blocks the activity of the promyelocytic protein, which is required for formation of the granules of promyelocytes and prevents further differentiation. Retinoic acids bind to the retinoic acid receptor (RAR alpha) component of the fusion product, resulting in degradation of the fusion protein by ubiquitinization. This allows normal PML to participate in granule formation and differentiation of the promyelocytes. In one common type of acute myeloid leukemia, which results in maturation arrest at the myeloid precursor level, there is a mutation of FLT3, a transmembrane tyrosine kinase, which results in constitutive activation of the IL-3 receptor. This may be blocked by agents that inhibit farnesyl transferase. In each of these examples, specific inhibition of the genetically altered activation molecules of the leukemic cells allows the leukemic cells to differentiate and die. Because acute myeloid leukemias usually have mutation of more than one gene, combinations of specific inhibitors that act on the effects of different specific genetic lesions promises to result in more effective and permanent treatment.
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PMID:Leukemia: stem cells, maturation arrest, and differentiation therapy. 1714 56

The success of targeting kinases in cancer with small molecule inhibitors has been tempered by the emergence of drug-resistant kinase domain mutations. In patients with chronic myeloid leukemia treated with ABL inhibitors, BCR-ABL kinase domain mutations are the principal mechanism of relapse. Certain mutations are occasionally detected before treatment, suggesting increased fitness relative to wild-type p210 BCR-ABL. We evaluated the oncogenicity of eight kinase inhibitor-resistant BCR-ABL mutants and found a spectrum of potencies greater or less than p210. Although most fitness alterations correlate with changes in kinase activity, this is not the case with the T315I BCR-ABL mutation that confers clinical resistance to all currently approved ABL kinase inhibitors. Through global phosphoproteome analysis, we identified a unique phosphosubstrate signature associated with each drug-resistant allele, including a shift in phosphorylation of two tyrosines (Tyr253 and Tyr257) in the ATP binding loop (P-loop) of BCR-ABL when Thr315 is Ile or Ala. Mutational analysis of these tyrosines in the context of Thr315 mutations demonstrates that the identity of the gatekeeper residue impacts oncogenicity by altered P-loop phosphorylation. Therefore, mutations that confer clinical resistance to kinase inhibitors can substantially alter kinase function and confer novel biological properties that may impact disease progression.
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PMID:Phosphorylation of the ATP-binding loop directs oncogenicity of drug-resistant BCR-ABL mutants. 1716 33

Dasatinib is an ATP-competitive, multi-targeted SRC and ABL kinase inhibitor that can bind BCR-ABL in both the active and inactive conformations. From a clinical standpoint, dasatinib is particularly attractive because it has been shown to induce hematologic and cytogenetic responses in imatinib-resistant chronic myeloid leukemia patients. The fact because the combination of imatinib and dasatinib shows the additive/synergistic growth inhibition on wild-type p210 BCR-ABL-expressing cells, we reasoned that these ABL kinase inhibitors might induce the different molecular pathways. To address this question, we used DNA microarrays to identify genes whose transcription was altered by imatinib and dasatinib. K562 cells were cultured with imatinib or dasatinib for 16 h, and gene expression data were obtained from three independent microarray hybridizations. Almost all of the imatinib- and dasatinib-responsive genes appeared to be similarly increased or decreased in K562 cells; however, small subsets of genes were identified as selectively altered expression by either imatinib or dasatinib. The distinct genes that are selectively modulated by dasatinib are cyclin-dependent kinase 2 (CDK2) and CDK8, which had a maximal reduction of <5-fold in microarray screen. To assess the functional importance of dasatinib regulated genes, we used RNA interference to determine whether reduction of CDK2 and CDK8 affected the growth inhibition. K562 and TF-1BCR-ABL cells, pretreated with CDK2 or CDK8 small interfering RNA, showed additive growth inhibition with imatinib, but not with dasatinib. These findings demonstrate that the additive/synergistic growth inhibition by imatinib and dasatinib may be mediated in part by CDK2 and CDK8.
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PMID:Identification and functional signature of genes regulated by structurally different ABL kinase inhibitors. 1721 9

Imatinib mesylate (Gleevec) has dramatically changed the strategy of chronic myeloid leukemia (CML) therapy. However, resistance is often reported in advanced-stage CML patients. Several novel tyrosine kinase inhibitors which have been developed to override imatinib resistance mechanism due to point mutations within the Abl kinase domain. Quite recently we successfully developed the novel Bcr-Abl/Lyn dual inhibitor INNO-406 (NS-187) which shows unique profile to overcome this resistance. Inhibitors of Abl tyrosine kinase are divided into two groups, ATP-competitive and non-competitive inhibitors. ATP-competitive inhibitors are further fall into two subclasses, the Src/Abl inhibitors and 2-phenylaminopyrimidin-based compounds. Dasatinib (BMS-354825, Sprycel) is classified as Src/Ablinhibitors while nilotinib (AMN 107) and INNO-406 (NS-187) belong to the latter. Among them, clinical studies on dasatinib and AMN 107 had started earlier than the others and favorable results are accumulating. We have performed basic and preclinical studies of INNO-406 (NS-187) in Japan, and then its clinical trials have been commenced firstly in the United States from July, 2006. The ultimate goal of clinical development is to bring the novel therapeutics with regulatory safety and efficacy to the clinical settings as soon as possible. Considerations important for the innovation of clinical trials for anti-cancer drugs in Japan are discussed.
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PMID:[Innovation of clinical trials for anti-cancer drugs in Japan--proposals from academia with special reference to the development of novel Bcr-Abl/Lyn tyrosine kinase inhibitor INNO-406 (NS-187) for imatinib-resistant chronic myelogenous leukemia]. 1730 49

Acquired imatinib resistance in chronic myelogenous leukemia (CML) can be the consequence of mutations in the kinase domain of BCR-ABL or increased protein levels. However, as in other malignancies, acquired resistance to cytostatic drugs is a common reason for treatment failure or disease progression. As a model for drug resistance, we developed a CML cell line resistant to cyclophosphamide (CP). Using oligonucleotide arrays, we examined changes in global gene expression. Selected genes were also examined by real-time PCR and flow cytometry. Neither the parent nor the resistant lines had mutations in their ATP binding domain. Filtering genes with a low-base line expression, a total of 239 genes showed significant changes (162 up- and 77 down-regulated) in the resistant clone. Most of the up-regulated genes were associated with metabolism, signal transduction, or encoded enzymes. The gene for aldehyde dehydrogenase 1 was over-expressed more than 2000-fold in the resistant clone. BCR-ABL was expressed in both cell lines to a comparable extent. When exposed to the tyrosine kinase inhibitors imatinib and nilotinib, both lines were sensitive. In conclusion, we found multiple genetic changes in a CML cell line resistant to CP related to metabolism, signal transduction or apoptosis. Despite these changes, the resistant cells retained sensitivity to tyrosine kinase inhibitors.
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PMID:Comparative gene expression analysis of a chronic myelogenous leukemia cell line resistant to cyclophosphamide using oligonucleotide arrays and response to tyrosine kinase inhibitors. 1740 35

Autophagy is an ancient cell survival pathway that allows cells to recoup ATP and essential building blocks for biosynthesis when they are starved of nutrients or when they are exposed to hypoxia, which are hallmarks of the tumor microenvironment. This pathway involves the formation of double-membraned vesicles, coined autophagosomes, which envelop bulk cellular material and/or organelles and that subsequently fuse with lysosomes that degrade their cargo. Autophagy has been suggested to play important roles in chemoresistance of cancer to some therapeutic agents, which typically induce an apoptotic response. For example, the histone deacetylase inhibitor SAHA induces both apoptosis and autophagy, suggesting that agents that disrupt the autophagy pathway might augment its efficacy as a therapeutic agent. We tested this notion in a model of Imatinib-refractory chronic myelogenous leukemia (CML) and in imatinib-resistant primary CML cells from patients bearing mutations in Bcr-Abl, including the T315I mutation that causes resistance to currently utilized tyrosine kinase inhibitors and translates into a very poor clinical prognosis. Agents that disrupt autophagy were shown to synergize with SAHA in provoking apoptotic death of these refractory tumors. These findings support the use of agents that disrupt the autophagy pathway in settings of chemorefractory malignancies.
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PMID:Modulating autophagy for therapeutic benefit. 1749 16


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