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Imatinib
Kinds of Imatinib Terms modified by Imatinib Selected AbstractsA BCR,JAK2 fusion gene as the result of a t(9;22)(p24;q11.2) translocation in a patient with a clinically typical chronic myeloid leukemiaGENES, CHROMOSOMES AND CANCER, Issue 3 2005Frank Griesinger Chronic myeloid leukemia (CML) is characterized by the presence of a t(9;22)(q34;q11.2), which leads to the well-known BCR,ABL1 fusion protein. We describe a patient who was diagnosed clinically with a typical CML but on cytogenetic analysis was found to have a t(9;22)(p24;q11.2). Chromosomal fluorescence in situ hybridization showed that the BCR gene locus spanned the breakpoint at band 22q11.2 but that the ABL1 gene was not rearranged. By means of a candidate gene approach, the JAK2 gene, at 9p24, was identified as the fusion partner of BCR in this case. The BCR,JAK2 fusion protein contains the coiled-coil dimerization domain of BCR and the protein tyrosine kinase domain (JH1) of JAK2. The patient's disease did not respond to Imatinib, and this unresponsiveness was most likely a result of the BCR,JAK2 fusion protein. © 2005 Wiley-Liss, Inc. [source] Therapy adapted to molecular response in patients with chronic myelogenous leukaemia in first chronic phase: results of the Duesseldorf study,HEMATOLOGICAL ONCOLOGY, Issue 4 2008Frank Neumann Abstract This study evaluates response-adapted treatment of chronic myelogenous leukaemia (CML) in chronic phase using molecular response criteria. bcr-abl/G6PDH ratios were assessed by Light-Cycler quantitative real-time polymerase chain reaction (PCR( in 277 peripheral blood samples from 33 patients, before and every 3 months during therapy. Sixty-six per cent (22/33) of the patients fulfiled our molecular response criterion of ,1 log decrease in bcr-abl transcript after 6 or ,2 log decrease after 9 and every following 3 months. Dose escalation was necessary for 33% (11/33) of the patients. Of these, 54% (6/11) achieved a reduction of bcr-abl mRNA by ,2 log (n,=,3) or ,3 log (n,=,3) with 800,mg Imatinib. Forty-five per cent (5/11) showed insufficient molecular response with 800,mg Imatinib and received Nilotinib. In conclusion, the assessment of molecular response permits an individual patient-tailored treatment of CML in first chronic phase, resulting in the majority of patients achieving a major molecular response after 2 years of therapy. Copyright © 2008 John Wiley & Sons, Ltd. [source] Clinical significance of oncogenic KIT and PDGFRA mutations in gastrointestinal stromal tumoursHISTOPATHOLOGY, Issue 3 2008J Lasota Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. Despite clinicopathological differences, GISTs share oncogenic KIT or platelet-derived growth factor-alpha (PDGFRA) mutations. Imatinib, KIT and PDGFRA inhibitor, has been successfully used in the treatment of metastatic GISTs. There are primary KIT or PDGFRA mutations diagnosed before imatinib treatment, linked to GIST pathogenesis, and secondary mutations detected during treatment, causing drug resistance. KIT exon 11 mutations are the most common. Gastric GISTs with exon 11 deletions are more aggressive than those with substitutions. KIT exon 11 mutants respond well to imatinib. Less common KIT exon 9 Ala502_Tyr503dup mutants occur predominantly in intestinal GISTs and are less sensitive to imatinib. An Asp842Val substitution in exon 18 is the most common PDGFRA mutation. GISTs with such mutation are resistant to imatinib. PDGFRA mutations are associated with gastric GISTs, epithelioid morphology and a less malignant course of disease. GISTs in neurofibromatosis 1, Carney triad and paediatric tumours generally lack KIT and PDGFRA mutations. Secondary KIT mutations affect exons 13,17. GISTs with secondary mutations in exon 13 and 14 are sensitive to sunitinib, another tyrosine kinase inhibitor. KIT and PDGFRA genotyping is important for GIST diagnosis and assessment of sensitivity to tyrosine kinase inhibitors. [source] Pml and TAp73 interacting at nuclear body mediate imatinib-induced p53-independent apoptosis of chronic myeloid leukemia cellsINTERNATIONAL JOURNAL OF CANCER, Issue 1 2009Jin-Hwang Liu Abstract Bcr-abl signals for leukemogenesis of chronic myeloid leukemia (CML) and activates ras. Since the function of promyelocytic leukemia protein (pml) is provoked by ras to promote apoptosis and senescence in untransformed cells, the function is probably masked in CML. Imatinib specifically inhibits bcr-abl and induces apoptosis of CML cells. As reported previously, p53wild CML was more resistant to imatinib than that lacking p53. Here, we searched for an imatinib-induced p53 independent proapoptotic mechanism. We found imatinib up-regulated phosphorylation of p38 mitogen-activated protein kinase (MAPK), checkpoint kinase 2 (chk2) and transactivation-competent (TA) p73; expression of pml and bax; formation of PML-nuclear body (NB); and co-localization of TAp73/PML-NB in p53-nonfunctioning K562 and p53mutant Meg-01 CML cells, but not in BCR-ABL - HL60 cells. In K562 cells, with short interfering RNAs (siRNAs), knockdown of pml led to dephosphorylation of TAp73. Knockdown of either pml or TAp73 abolished the imatinib-induced apoptosis. Inhibition of p38 MAPK with SB203580 led to dephosphorylation of TAp73, abolishment of TAp73/PML-NB co-localization, and the subsequent apoptosis. Conversely, interferon ,-2a (IFN,), which increased phosphrylated TAp73 and TAp73/PML-NB co-localization, increased additively apoptosis with imatinib. The imatinib-induced TAp73/PML-NB co-localization was accompanied by co-immpunoprecipitation of TAp73 with pml. The imatinib-induced co-localization was also found in primary CML cells from 3 of 6 patients, including 2 with p53mutant and one with p53wild. A novel p53-independent proapoptotic mechanism using p38 MAPK /pml/TAp73 axis with a step processing at PML-NB and probably with chk2 and bax being involved is hereby evident in some imatinib-treated CML cells. © 2009 UICC [source] Imatinib mesylate suppresses bone metastases of breast cancer by inhibiting osteoclasts through the blockade of c-Fms signalsINTERNATIONAL JOURNAL OF CANCER, Issue 1 2009Toru Hiraga Abstract Imatinib mesylate (imatinib) is a potent and selective inhibitor of the tyrosine kinases, Bcr-Abl, c-Kit and platelet-derived growth factor receptors (PDGFRs). Recently, it has been reported that imatinib also targets the macrophage colony-stimulating factor (M-CSF) receptor c-Fms. M-CSF signals are essential for the differentiation of osteoclasts. Bone metastases of breast cancer are frequently associated with osteoclastic bone destruction. Furthermore, several lines of evidence suggest that osteoclasts play central roles in the development and progression of bone metastases. Thus, in the present study, we examined the effects of imatinib on bone metastases of breast cancer. Coimmunoprecipitation assays showed that imatinib inhibited the M-CSF-induced phosphorylation of c-Fms in osteoclast precursor cells as well as the PDGF-induced PDGFR phosphorylation in MDA-MB-231 human breast cancer cells. Imatinib also markedly reduced osteoclast formation in vitro. In contrast, those concentrations of imatinib did not affect osteoblast differentiation. We then examined the effects of imatinib on bone metastases of MDA-MB-231 cells in a nude mouse model. Radiographic and histomorphometric analyses demonstrated that imatinib significantly decreased bone metastases associated with the reduced number of osteoclasts. In support of the notion that the inhibition of c-Fms acts to suppress the development of bone metastases, we found that a specific inhibitor of c-Fms Ki20227 also decreased bone metastases. In conclusion, these results collectively suggest that imatinib reduced bone metastases, at least in part, by inhibiting osteoclastic bone destruction through the blockade of c-Fms signals. Our results also suggest that imatinib may have a protective effect against cancer treatment-induced bone loss. © 2008 Wiley-Liss, Inc. [source] Lack of inhibitory effects of the anti-fibrotic drug imatinib on endothelial cell functions in vitro and in vivoJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 10 2009Paulius Venalis Abstract Systemic sclerosis (SSc) is a systemic autoimmune disease that is characterized by microangiopathy with progressive loss of capillaries and tissue fibrosis. Imatinib exerts potent anti-fibrotic effects and is currently evaluated in clinical trials. The aim of the present study was to exclude that the anti-fibrotic effects of imatinib are complicated by inhibitory effects on endothelial cell functions, which might augment vascular disease in SSc. Endothelial cells and mice were treated with pharmacologically relevant concentrations of imatinib. The expression of markers of vascular activation was assessed with real-time PCR. Proliferation was analysed with the cell counting experiments and the MTT assay. Apoptosis was quantified with caspase 3 assays, annexin V in vitro and with TUNEL staining in vivo. Migration was studied with scratch and transwell assays. Tube forming was investigated with the matrigel assay. Imatinib did not alter the expression of markers of vascular activation. Imatinib did not increase the percentage of annexin V positive cells or the activity of caspase 3. No reduction in proliferation or metabolic activity of endothelial cells was observed. Imatinib did not affect migration of endothelial cells and did not reduce the formation of capillary tubes. Consistent with the in vitro data, no difference in the number of apoptotic endothelial cells was observed in vivo in mice treated with imatinib. Imatinib does not inhibit activation, viability, proliferation, migration or tube forming of endothelial cells in vitro and in vivo. Thus, treatment with imatinib might not augment further endothelial cell damage in SSc. [source] Quantification of change in phosphorylation of BCR-ABL kinase and its substrates in response to Imatinib treatment in human chronic myelogenous leukemia cellsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 16 2006Xiquan Liang Dr. Abstract Phosphorylation by the constitutively activated BCR-ABL tyrosine kinase is associated with the pathogenesis of the human chronic myelogenous leukemia,(CML). It is difficult to characterize kinase response to stimuli or drug treatment because regulatory phosphorylation events are largely transient changes affecting low abundance proteins. Stable isotope labeling with amino acids in cell culture,(SILAC) has emerged as a pivotal technology for quantitative proteomics. By metabolically labeling proteins with light or heavy tyrosine, we are able to quantify the change in phosphorylation of BCR-ABL kinase and its substrates in response to drug treatment in human CML cells. In this study, we observed that BCR-ABL kinase is phosphorylated at tyrosines,393 and 644, and that SH2-domain containing inositol phosphatase (SHIP)-2 and downstream of kinase (Dok)-2 are phosphorylated at tyrosine,1135 and 299, respectively. Based on the relative intensity of isotopic peptide pairs, we demonstrate that the level of phosphorylation of BCR-ABL kinase as well as SHIP-2 and Dok-2 is reduced approximately 90% upon treatment with Imatinib, a specific inhibitor of BCR-ABL kinase. Furthermore, proteins, such as SHIP-1, SH2-containing protein (SHC) and Casitas B-lineage lymphoma proto-oncogene (CBL), are also regulated by Imatinib. These results demonstrate the simplicity and utility of SILAC as a method to quantify dynamic changes in phosphorylation at specific sites in response to stimuli or drug treatment in cell culture. [source] Treatment with imatinib prevents fibrosis in different preclinical models of systemic sclerosis and induces regression of established fibrosisARTHRITIS & RHEUMATISM, Issue 1 2009Alfiya Akhmetshina Objective Imatinib is a small-molecule tyrosine kinase inhibitor capable of selective, dual inhibition of the transforming growth factor , and platelet-derived growth factor (PDGF) pathways. Imatinib has previously been shown to prevent the development of inflammation-driven experimental fibrosis when treatment was initiated before administration of the profibrotic stimulus. The aim of this study was to confirm the efficacy of imatinib in a murine model of systemic sclerosis (SSc) that is less driven by inflammation and to investigate whether imatinib is also effective for the treatment of established fibrosis. Methods The tight skin 1 (TSK-1) mouse model of SSc was used to evaluate the antifibrotic effects of imatinib in a genetic model of the later stages of SSc. In addition, the efficacy of imatinib for the treatment of preestablished fibrosis was analyzed in a modified model of bleomycin-induced dermal fibrosis in which the application of bleomycin was prolonged and the onset of treatment was late. Results Treatment with imatinib reduced dermal and hypodermal thickening in TSK-1 mice and prevented the differentiation of resting fibroblasts into myofibroblasts. In the model of preestablished dermal fibrosis, imatinib not only stopped further progression of fibrosis but also induced regression of preexisting dermal fibrosis, with a reduction in dermal thickness below pretreatment levels. Conclusion These results indicate that combined inhibition of the tyrosine kinase c-Abl and PDGF receptor might be effective in the later, less inflammatory stages of SSc and for the treatment of established fibrosis. Thus, imatinib might be an interesting candidate for clinical trials in patients with longstanding disease and preexisting tissue fibrosis. [source] Determination of imatinib mesylate and its main metabolite (CGP74588) in human plasma and murine specimens by ion-pairing reversed-phase high-performance liquid chromatographyBIOMEDICAL CHROMATOGRAPHY, Issue 7 2007Roos L. Oostendorp Abstract A sensitive reversed-phase high-performance liquid chromatographic (HPLC) method has been developed and validated for the determination of imatinib, a tyrosine kinase inhibitor, and its main metabolite N -desmethyl-imatinib (CGP74588) in human plasma and relevant murine biological matrices. A simple HPLC assay for the individual quantification of imatinib and CGP74588 in murine specimens has not been reported to date. Sample pre-treatment involved liquid,liquid extraction with tert -butyl-methyl ether. Imatinib, CGP74588 (metabolite) and the internal standard 4-hydroxybenzophenone were separated using a narrow bore (2.1 × 150 mm) stainless steel Symmetry C18 column and detected by UV at 265 nm. The mobile phase consisted of 28% (v/v) acetonitrile in 50 mm ammonium acetate buffer pH 6.8 containing 0.005 m 1-octane sulfonic acid and was delivered at 0.2 mL/min. The calibration curve was prepared in blank human plasma and was linear over the dynamic range 10 ng/mL to 10 µg/mL). The accuracy was close to 100% and the within-day and between-day precisions were within the generally accepted 15% range. The validation results showed that the assay was selective and reproducible. This method was applied to study the pharmacokinetics of imatinib and its main metabolite in human and mice. Copyright © 2007 John Wiley & Sons, Ltd. [source] Fusion of PDGFRB to two distinct loci at 3p21 and a third at 12q13 in imatinib-responsive myeloproliferative neoplasmsBRITISH JOURNAL OF HAEMATOLOGY, Issue 2 2010Claire Hidalgo-Curtis Summary We identified four patients who presented with BCR-ABL1 negative myeloproliferative neoplasms and cytogenetically visible abnormalities of chromosome band 5q31-35. Fluorescence in situ hybridization indicated that the platelet-derived growth factor receptor , gene (PDGFRB) was disrupted in all four cases and 5, rapid amplification of cDNA ends identified in-frame mRNA fusions between PDGFRB and WDR48 (3p21), GOLGA4 (3p21) and BIN2 (12q13). Strikingly, all three genes encode proteins involving intracellular trafficking. Imatinib, a known inhibitor of PDGFR,, selectively blocked the growth of t(3;5) myeloid colonies and produced clinically significant responses in all patients. We conclude that PDGFRB fuses to diverse partner genes in atypical myeloproliferative neoplasms (MPNs). Although very rare, identification of these fusions is critical for proper management of affected individuals. [source] A short low-dose imatinib trial allows rapid identification of responsive patients in hypereosinophilic syndromesBRITISH JOURNAL OF HAEMATOLOGY, Issue 5 2009Tamara Intermesoli Summary Although imatinib may be effective in hypereosinophilic syndromes, the exact response kinetics are not known. Imatinib was administered at 100,400 mg/d each week in a 12-week response-oriented schedule, targeting a complete clinical and haematological remission (CR). CR was achieved in 11/23 patients (6/6 with FIP1L1 - PDGRFA rearrangement and 5/17 without, P = 0·006), most after 2 weeks of 100 mg/d imatinib. The maximum imatinib dose had no effect in early unresponsive patients. Low-dose, short-course imatinib may represent a rational choice for identifying responsive cases, both within and outside the pre-defined FIP1L1 rearrangement subset. [source] Phase I pharmacokinetic study of the vascular endothelial growth factor receptor tyrosine kinase inhibitor vatalanib (PTK787) plus imatinib and hydroxyurea for malignant gliomaCANCER, Issue 10 2009David A. Reardon MD Abstract BACKGROUND: This study determined the maximum tolerated dose (MTD) and dose-limiting toxicities (DLT) of the oral vascular endothelial growth factor receptor (VEGFR) inhibitor, vatalanib, when administered with imatinib and hydroxyurea on a continuous daily schedule among recurrent malignant glioma patients. METHODS: All patients received 500 mg of hydroxyurea twice daily. Imatinib was dosed at 400 mg per day for patients not taking enzyme-inducing antiepileptic drugs (EIAEDs; stratum A) and at 500 mg twice-a-day for patients taking EIAEDs (stratum B). Vatalanib was escalated from 500 mg to 1250 mg twice daily in successive cohorts, independently for each stratum. Pharmacokinetics of each drug were assessed. RESULTS: A total of 37 recurrent patients, 34 (92%) with glioblastoma and 3 (8%) with grade 3 malignant glioma, were enrolled. Nineteen patients (51%) were taking EIAEDs. The MTD of vatalanib for all patients was 1000 mg twice-a-day. DLTs were hematologic, gastrointestinal, renal, and hepatic. No patients developed intracranial hemorrhage. Concurrent administration of imatinib and hydroxyurea did not affect vatalanib exposure, but EIAEDs decreased vatalanib and imatinib plasma exposures. CONCLUSIONS: Vatalanib doses up to 1000 mg twice-a-day combined with imatinib and hydroxyurea were well tolerated. Strategies to target tumor blood vessel endothelial cells and pericytes by inhibiting VEGFR and platelet-derived growth factor, respectively, were safe among recurrent malignant glioma patients and may enhance antiangiogenesis activity. Cancer 2009. © 2009 American Cancer Society. [source] Imatinib compared with chemotherapy as front-line treatment of elderly patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL),CANCER, Issue 10 2007Oliver G. Ottmann MD Abstract BACKGROUND Elderly patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) have a poor prognosis, with a low complete remission (CR) rate, high induction mortality, and short remission duration. Imatinib (IM) has a favorable toxicity profile but limited antileukemic activity in advanced Ph+ALL. Imatinib in combination with intensive chemotherapy has yielded promising results as front-line therapy, but its value as monotherapy in newly diagnosed Ph+ALL is not known. METHODS Patients with de novo Ph+ALL were randomly assigned to induction therapy with either imatinib (IndIM) or multiagent, age-adapted chemotherapy (Indchemo). Imatinib was subsequently coadministered with consolidation chemotherapy. RESULTS In all, 55 patients (median age, 68 years) were enrolled. The overall CR rate was 96.3% in patients randomly assigned to IndIM and 50% in patients allocated to Indchemo (P = .0001). Nine patients (34.6%) were refractory and 2 patients died during Indchemo; none failed imatinib induction. Severe adverse events were significantly more frequent during Indchemo (90% vs 39%; P = .005). The estimated overall survival (OS) of all patients was 42% ± 8% at 24 months, with no significant difference between the 2 cohorts. Median disease-free survival was significantly longer in the 43% of patients (21 of 49 evaluable) in whom BCR-ABL transcripts became undetectable (18.3 months vs 7.2 months; P = .002). CONCLUSIONS In elderly patients with de novo Ph+ALL, imatinib induction results in a significantly higher CR rate and lower toxicity than induction chemotherapy. With subsequent combined imatinib and chemotherapy consolidation, this initial benefit does not translate into improved survival compared with chemotherapy induction. Cancer 2007. © 2007 American Cancer Society. [source] Clinical relevance of the homologous recombination machinery in cancer therapyCANCER SCIENCE, Issue 2 2008Kiyoshi Miyagawa Cancer chemotherapy and radiotherapy kill cancer cells by inducing DNA damage, unless the lesions are repaired by intrinsic repair pathways. DNA double-strand breaks (DSB) are the most deleterious type of damage caused by cancer therapy. Homologous recombination (HR) is one of the major repair pathways for DSB and is thus a potential target of cancer therapy. Cells with a defect in HR have been shown to be sensitive to a variety of DNA-damaging agents, particularly interstrand crosslink (ICL)-inducing agents such as mitomycin C and cisplatin. These findings have recently been applied to clinical studies of cancer therapy. ERCC1, a structure-specific endonuclease involved in nucleotide excision repair (NER) and HR, confers resistance to cisplatin. Patients with ERCC1-negative non-small-cell lung cancer were shown to benefit from adjuvant cisplatin-based chemotherapy. Imatinib, an inhibitor of the c-Abl kinase, has been investigated as a sensitizer in DNA-damaging therapy, because c-Abl activates Rad51, which plays a key role in HR. Furthermore, proteins involved in HR have been shown to repair DNA damage induced by a variety of other chemotherapeutic agents, including camptothecin and gemcitabine. These findings highlight the importance of HR machinery in cancer therapy. (Cancer Sci 2008; 99: 187,194) [source] Are MAP Kinases Drug Targets?CHEMMEDCHEM, Issue 8 2007but Difficult Ones Abstract Pharmaceutical companies are facing an increasing interest in new target identification and validation. In particular, extensive efforts are being made in the field of protein kinase inhibitors research and development, and the past ten years of effort in this field have altered our perception of the potential of kinases as drug targets. Therefore, in the drug discovery process, the selection of relevant, susceptible protein kinase targets combined with searches for leads and candidates have become a crucial approach. The success of recent launches of protein kinase inhibitors (Gleevec, Imatinib, Sutent, Iressa, Nexavar, Sprycel) gave another push to this field. Numerous other kinase inhibitors are currently undergoing clinical trials or clinical development. Some questions are nevertheless unanswered, mostly related to the great number of known kinases in the human genome, to their similarity with each other, to the existence of functionally redundant kinases for specific pathways, and also because the connection between particular pathways and diseases is not always clear. The review is leading the reader through a panoramic view of protein kinase inhibition with a major focus on MAPK, successful examples and clinical candidates. [source] Allogeneic haematopoietic cell transplantation for chronic myelogenous leukaemia in the era of imatinib: a retrospective multicentre studyEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 1 2006Martin Bornhäuser Abstract:,Objective:,To analyse the results of allogeneic haematopoietic cell transplantation (HCT) in patients with advanced stages of Philadelphia chromosome-positive chronic myelogenous leukaemia (CML) who had previously been treated with imatinib mesylate (IM). Methods:,We analysed the outcome of 61 patients with CML who had received allogeneic HCT from sibling (n = 18) or unrelated (n = 43) donors after having been treated with IM. Forty-one patients had received IM because of accelerated or blast phase CML. Conditioning therapy contained standard doses of busulfan (n = 25) or total-body irradiation (n = 20) in conjunction with cyclophosphamide in the majority of cases. Sixteen patients received dose-reduced conditioning with fludarabine-based regimens. Results:,The incidence of grades II,IV and III,IV graft-versus-host disease was 66% and 38% respectively. The probability of overall survival (OS), disease-free survival (DFS) and relapse at 18 months for the whole patient cohort were 37%, 33% and 24% respectively. The probability of non-relapse mortality (NRM) at 100 d and 12 months was 30% and 46% respectively. Univariate analysis showed that fludarabine-based conditioning therapy, age ,40 yr and >12 months interval between diagnosis and transplantation were associated with a significantly lower OS and DFS and a higher NRM. Conclusion:,These data suggest that although pretreatment with IM is not an independent negative prognostic factor, it cannot improve the dismal prognosis of CML patients at high risk for transplant-related mortality. [source] Gene expression analysis of BCR/ABL1-dependent transcriptional response reveals enrichment for genes involved in negative feedback regulationGENES, CHROMOSOMES AND CANCER, Issue 4 2008Petra Håkansson Philadelphia (Ph) chromosome-positive leukemia is characterized by the BCR/ABL1 fusion protein that affects a wide range of signal transduction pathways. The knowledge about its downstream target genes is, however, still quite limited. To identify novel BCR/ABL1-regulated genes we used global gene expression profiling of several Ph-positive and Ph-negative cell lines treated with imatinib. Following imatinib treatment, the Ph-positive cells showed decreased growth, viability, and reduced phosphorylation of BCR/ABL1 and STAT5. In total, 142 genes were identified as being dependent on BCR/ABL1-mediated signaling, mainly including genes involved in signal transduction, e.g. the JAK/STAT, MAPK, TGFB, and insulin signaling pathways, and in regulation of metabolism. Interestingly, BCR/ABL1 was found to activate several genes involved in negative feedback regulation (CISH, SOCS2, SOCS3, PIM1, DUSP6, and TNFAIP3), which may act to indirectly suppress the tumor promoting effects exerted by BCR/ABL1. In addition, several genes identified as deregulated upon BCR/ABL1 expression could be assigned to the TGFB and NFkB signaling pathways, as well as to reflect the metabolic adjustments needed for rapidly growing cells. Apart from providing important pathogenetic insights into BCR/ABL1 -mediated leukemogenesis, the present study also provides a number of pathways/individual genes that may provide attractive targets for future development of targeted therapies. This article contains Supplementary Material available at http://www.interscience.wiley.com/jpages/1045,2257/suppmat. © 2008 Wiley-Liss, Inc. [source] Clinical significance of oncogenic KIT and PDGFRA mutations in gastrointestinal stromal tumoursHISTOPATHOLOGY, Issue 3 2008J Lasota Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. Despite clinicopathological differences, GISTs share oncogenic KIT or platelet-derived growth factor-alpha (PDGFRA) mutations. Imatinib, KIT and PDGFRA inhibitor, has been successfully used in the treatment of metastatic GISTs. There are primary KIT or PDGFRA mutations diagnosed before imatinib treatment, linked to GIST pathogenesis, and secondary mutations detected during treatment, causing drug resistance. KIT exon 11 mutations are the most common. Gastric GISTs with exon 11 deletions are more aggressive than those with substitutions. KIT exon 11 mutants respond well to imatinib. Less common KIT exon 9 Ala502_Tyr503dup mutants occur predominantly in intestinal GISTs and are less sensitive to imatinib. An Asp842Val substitution in exon 18 is the most common PDGFRA mutation. GISTs with such mutation are resistant to imatinib. PDGFRA mutations are associated with gastric GISTs, epithelioid morphology and a less malignant course of disease. GISTs in neurofibromatosis 1, Carney triad and paediatric tumours generally lack KIT and PDGFRA mutations. Secondary KIT mutations affect exons 13,17. GISTs with secondary mutations in exon 13 and 14 are sensitive to sunitinib, another tyrosine kinase inhibitor. KIT and PDGFRA genotyping is important for GIST diagnosis and assessment of sensitivity to tyrosine kinase inhibitors. [source] Is there a role for imatinib in inflammatory bowel disease?INFLAMMATORY BOWEL DISEASES, Issue 4 2008Ole De Backer MD No abstract is available for this article. [source] NF-,B inhibition triggers death of imatinib-sensitive and imatinib-resistant chronic myeloid leukemia cells including T315I Bcr-Abl mutantsINTERNATIONAL JOURNAL OF CANCER, Issue 2 2009Nadia Lounnas Abstract The Bcr-Abl inhibitor imatinib is the current first-line therapy for all newly diagnosed chronic myeloid leukemia (CML). Nevertheless, resistance to imatinib emerges as CML progresses to an acute deadly phase implying that physiopathologically relevant cellular targets should be validated to develop alternative therapeutic strategies. The NF-,B transcription factor that exerts pro-survival actions is found abnormally active in numerous hematologic malignancies. In the present study, using Bcr-Abl-transfected BaF murine cells, LAMA84 human CML cell line and primary CML, we show that NF-,B is active downstream of Bcr-Abl. Pharmacological blockade of NF-,B by the IKK2 inhibitor AS602868 prevented survival of BaF cells expressing either wild-type, M351T or T315I imatinib-resistant mutant forms of Bcr-Abl both in vitro and in vivo using a mouse xenograft model. AS602868 also affected the survival of LAMA84 cells and of an imatinib-resistant variant. Importantly, the IKK2 inhibitor strongly decreased in vitro survival and ability to form hematopoietic colonies of primary imatinib resistant CML cells including T315I cells. Our data strongly support the targeting of NF-,B as a promising new therapeutic opportunity for the treatment of imatinib resistant CML patients in particular in the case of T315I patients. The T315I mutation escapes all currently used Bcr-Abl inhibitors and is likely to become a major clinical problem as it is associated with a poor clinical outcome. © 2009 UICC [source] Pml and TAp73 interacting at nuclear body mediate imatinib-induced p53-independent apoptosis of chronic myeloid leukemia cellsINTERNATIONAL JOURNAL OF CANCER, Issue 1 2009Jin-Hwang Liu Abstract Bcr-abl signals for leukemogenesis of chronic myeloid leukemia (CML) and activates ras. Since the function of promyelocytic leukemia protein (pml) is provoked by ras to promote apoptosis and senescence in untransformed cells, the function is probably masked in CML. Imatinib specifically inhibits bcr-abl and induces apoptosis of CML cells. As reported previously, p53wild CML was more resistant to imatinib than that lacking p53. Here, we searched for an imatinib-induced p53 independent proapoptotic mechanism. We found imatinib up-regulated phosphorylation of p38 mitogen-activated protein kinase (MAPK), checkpoint kinase 2 (chk2) and transactivation-competent (TA) p73; expression of pml and bax; formation of PML-nuclear body (NB); and co-localization of TAp73/PML-NB in p53-nonfunctioning K562 and p53mutant Meg-01 CML cells, but not in BCR-ABL - HL60 cells. In K562 cells, with short interfering RNAs (siRNAs), knockdown of pml led to dephosphorylation of TAp73. Knockdown of either pml or TAp73 abolished the imatinib-induced apoptosis. Inhibition of p38 MAPK with SB203580 led to dephosphorylation of TAp73, abolishment of TAp73/PML-NB co-localization, and the subsequent apoptosis. Conversely, interferon ,-2a (IFN,), which increased phosphrylated TAp73 and TAp73/PML-NB co-localization, increased additively apoptosis with imatinib. The imatinib-induced TAp73/PML-NB co-localization was accompanied by co-immpunoprecipitation of TAp73 with pml. The imatinib-induced co-localization was also found in primary CML cells from 3 of 6 patients, including 2 with p53mutant and one with p53wild. A novel p53-independent proapoptotic mechanism using p38 MAPK /pml/TAp73 axis with a step processing at PML-NB and probably with chk2 and bax being involved is hereby evident in some imatinib-treated CML cells. © 2009 UICC [source] Imatinib mesylate suppresses bone metastases of breast cancer by inhibiting osteoclasts through the blockade of c-Fms signalsINTERNATIONAL JOURNAL OF CANCER, Issue 1 2009Toru Hiraga Abstract Imatinib mesylate (imatinib) is a potent and selective inhibitor of the tyrosine kinases, Bcr-Abl, c-Kit and platelet-derived growth factor receptors (PDGFRs). Recently, it has been reported that imatinib also targets the macrophage colony-stimulating factor (M-CSF) receptor c-Fms. M-CSF signals are essential for the differentiation of osteoclasts. Bone metastases of breast cancer are frequently associated with osteoclastic bone destruction. Furthermore, several lines of evidence suggest that osteoclasts play central roles in the development and progression of bone metastases. Thus, in the present study, we examined the effects of imatinib on bone metastases of breast cancer. Coimmunoprecipitation assays showed that imatinib inhibited the M-CSF-induced phosphorylation of c-Fms in osteoclast precursor cells as well as the PDGF-induced PDGFR phosphorylation in MDA-MB-231 human breast cancer cells. Imatinib also markedly reduced osteoclast formation in vitro. In contrast, those concentrations of imatinib did not affect osteoblast differentiation. We then examined the effects of imatinib on bone metastases of MDA-MB-231 cells in a nude mouse model. Radiographic and histomorphometric analyses demonstrated that imatinib significantly decreased bone metastases associated with the reduced number of osteoclasts. In support of the notion that the inhibition of c-Fms acts to suppress the development of bone metastases, we found that a specific inhibitor of c-Fms Ki20227 also decreased bone metastases. In conclusion, these results collectively suggest that imatinib reduced bone metastases, at least in part, by inhibiting osteoclastic bone destruction through the blockade of c-Fms signals. Our results also suggest that imatinib may have a protective effect against cancer treatment-induced bone loss. © 2008 Wiley-Liss, Inc. [source] Prolonged imatinib-induced myelosuppression in chronic myeloid leukaemia with an unusually long survivalINTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 1 2008D. P. Busuttil Summary A case of Philadelphia chromosome positive chronic myeloid leukaemia (CML) with the longest survival ever reported in the medical literature is presented. The duration of the chronic phase was 29 years, the overall survival being 31 years. The clinical course, when challenged with imatinib in the later stages of the disease, was at variance with what is to be expected from the experience in similar situations. Lifelong myelosuppression resulted that interfered with further therapy and contributed to the demise of the patient from sepsis three years later. Caution is suggested with the use of imatinib in fibrotic CML with a low platelet count. [source] Lack of inhibitory effects of the anti-fibrotic drug imatinib on endothelial cell functions in vitro and in vivoJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 10 2009Paulius Venalis Abstract Systemic sclerosis (SSc) is a systemic autoimmune disease that is characterized by microangiopathy with progressive loss of capillaries and tissue fibrosis. Imatinib exerts potent anti-fibrotic effects and is currently evaluated in clinical trials. The aim of the present study was to exclude that the anti-fibrotic effects of imatinib are complicated by inhibitory effects on endothelial cell functions, which might augment vascular disease in SSc. Endothelial cells and mice were treated with pharmacologically relevant concentrations of imatinib. The expression of markers of vascular activation was assessed with real-time PCR. Proliferation was analysed with the cell counting experiments and the MTT assay. Apoptosis was quantified with caspase 3 assays, annexin V in vitro and with TUNEL staining in vivo. Migration was studied with scratch and transwell assays. Tube forming was investigated with the matrigel assay. Imatinib did not alter the expression of markers of vascular activation. Imatinib did not increase the percentage of annexin V positive cells or the activity of caspase 3. No reduction in proliferation or metabolic activity of endothelial cells was observed. Imatinib did not affect migration of endothelial cells and did not reduce the formation of capillary tubes. Consistent with the in vitro data, no difference in the number of apoptotic endothelial cells was observed in vivo in mice treated with imatinib. Imatinib does not inhibit activation, viability, proliferation, migration or tube forming of endothelial cells in vitro and in vivo. Thus, treatment with imatinib might not augment further endothelial cell damage in SSc. [source] Emerging targets and novel strategies in the treatment of AIDS-related Kaposi's sarcoma: Bidirectional translational scienceJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2006Bruce J. Dezube Through the mentorship process, Dr. Arthur Pardee emphasized the critical importance of bidirectional translational research,not only advancing drug development from bench to bedside, but also bringing back precious clinical material to the laboratory to assess the biologic effects of therapeutic agents on their targets. This mini-review focuses on the signal transduction pathways of Kaposi's sarcoma (KS) and on how the knowledge of such pathways has led to the rational development of molecularly targeted pathogenesis-driven therapies. Acquired immune deficiency syndrome (AIDS) related-KS results from co-infection with human immunodeficiency virus and KS herpesvirus/human herpesvirus-8 (KSHV/HHV8), which leads to the development of an angiogenic-inflammatory state that is critical in the pathogenesis of KS. KS is driven by KSHV/HHV8-specific pathways, which include viral G protein-coupled receptor (vGPCR), viral interleukin-6 (vIL-6), and viral chemokine homologues. In addition, cellular growth/angiogenic pathways, such as vascular endothelial growth factor (VEGF), insulin-like growth factor, platelet-derived growth factor (PDGF), angiopoietin and matrix metalloproteinases (MMPs) are "pirated" by KSHV/HHV8. As a very tangible example of how translational research has led to a marked improvement in patient outcome, the signal transduction inhibitor imatinib (a tyrosine kinase inhibitor of c-kit and PDGF) was administered to patients with KS whose tumors were serially biopsied. Not only did the patients' tumors regress, but also the regression was correlated with the inhibition of PDGF receptor (PDGFR) in the biopsy samples. Recent and future clinical trials of molecularly targeted therapy for the treatment of KS are a prelude to a shift in the paradigm of how KS is managed. J. Cell. Physiol. 209: 659,662, 2006. © 2006 Wiley-Liss, Inc. [source] Neoadjuvant treatment of soft-tissue sarcoma: A multimodality approachJOURNAL OF SURGICAL ONCOLOGY, Issue 4 2010David Reynoso BS Abstract Unlike epithelial cancers that are both more homogeneous and easily categorized by their respective tissues of origin (e.g., breast or lung cancer), sarcomas represent a diverse class of molecularly distinct bone and soft-tissue mesenchymal neoplasms of more than 50 subtypes. This diversity, as well as the relative rarity of sarcomas as a whole, has presented challenges in conducting prospective randomized clinical trials to assess the value of neoadjuvant chemotherapy for any given subtype. Most clinical trials and meta-analyses have neglected the phenotypic and molecular heterogeneity differentiating one sarcoma subtype from another in favor of a simplified grouping that ensures timely trial completion. As the success of treating gastrointestinal stromal tumors (GISTs) with imatinib demonstrates, a decision to provide neoadjuvant chemotherapy must take into consideration both the subtype being treated and the effect such treatment would be expected to exert upon that subtype. J. Surg. Oncol. 2010; 101:327,333. © 2010 Wiley-Liss, Inc. [source] A novel FIP1L1-PDGFRA mutant destabilizing the inactive conformation of the kinase domain in chronic eosinophilic leukemia/hypereosinophilic syndromeALLERGY, Issue 6 2009S. Salemi Background:, The Fip1-like-1,platelet-derived growth factor receptor alpha (FIP1L1-PDGFRA) gene fusion is a common cause of chronic eosinophilic leukemia (CEL)/hypereosinophilic syndrome (HES), and patients suffering from this particular subgroup of CEL/HES respond to low-dose imatinib therapy. However, some patients may develop imatinib resistance because of an acquired T674I mutation, which is believed to prevent drug binding through steric hindrance. Methods:, In an imatinib resistant FIP1L1-PDGFRA positive patient, we analyzed the molecular structure of the fusion gene and analyzed the effect of several kinase inhibitors on FIP1L1-PDGFRA-mediated proliferative responses in vitro. Results:, Sequencing of the FIP1L1-PDGFRA fusion gene revealed the occurrence of a S601P mutation, which is located within the nucleotide binding loop. In agreement with the clinical observations, imatinib did not inhibit the proliferation of S601P mutant FIP1L1-PDGFRA-transduced Ba/F3 cells. Moreover, sorafenib, which has been described to inhibit T674I mutant FIP1L1-PDGFRA, failed to block S601P mutant FIP1L1-PDGFRA. Structural modeling revealed that the newly identified S601P mutated form of PDGFRA destabilizes the inactive conformation of the kinase domain that is necessary to bind imatinib as well as sorafenib. Conclusions:, We identified a novel mutation in FIP1L1-PDGFRA resulting in both imatinib and sorafenib resistance. The identification of novel drug-resistant FIP1L1-PDGFRA variants may help to develop the next generation of target-directed compounds for CEL/HES and other leukemias. [source] The flavonoid tangeretin activates the unfolded protein response and synergizes with imatinib in the erythroleukemia cell line K562MOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 6 2010Sofie Lust Abstract We explored the mechanism of cell death of the polymethoxyflavone tangeretin (TAN) in K562 breakpoint cluster region-abelson murine leukemia (Bcr-Abl+) cells. Flow cytometric analysis showed that TAN arrested the cells in the G2/M phase and stimulated an accumulation of the cells in the sub-G0 phase. TAN-induced cell death was evidenced by poly(ADP)-ribose polymerase cleavage, DNA laddering fragmentation, activation of the caspase cascade and downregulation of the antiapoptotic proteins Mcl-1 and Bcl-xL. Pretreatment with the pancaspase inhibitor Z-VAD-FMK_blocked caspase activation and cell cycle arrest but did not inhibit apoptosis which suggest that other cell killing mechanisms like endoplasmic reticulum (ER)-associated cell death pathways could be involved. We demonstrated that TAN-induced apoptosis was preceded by a rapid activation of the proapoptotic arm of the unfolded protein response, namely PKR-like ER kinase. This was accompanied by enhanced levels of glucose-regulated protein of 78,kDa and of spliced X-box binding protein 1. Furthermore, TAN sensitized K562 cells to the cell killing effects of imatinib via an apoptotic mechanism. In conclusion, our results suggest that TAN is able to induce apoptosis in Bcr-Abl+ cells via cell cycle arrest and the induction of the unfolded protein response, and has synergistic cytotoxicity with imatinib. [source] XPC genetic polymorphisms correlate with the response to imatinib treatment in patients with chronic phase chronic myeloid leukemia,AMERICAN JOURNAL OF HEMATOLOGY, Issue 7 2010Vicent M. Guillem Chronic myeloid leukemia (CML) is driven by the BCR-ABL protein, which promotes the proliferation and viability of the leukemic cells. Moreover, BCR-ABL induces genomic instability that can contribute to the emergence of resistant clones to the ABL kinase inhibitors. It is currently unknown whether the inherited individual capability to repair DNA damage could affect the treatment results. To address this, a comprehensive analysis of single nucleotide polimorfisms (SNPs) on the nucleotide excision repair (NER) genes (ERCC2-ERCC8, RPA1-RPA3, LIG1, RAD23B, XPA, XPC) was performed in 92 chronic phase CML patients treated with imatinib upfront. ERCC5 and XPC SNPs correlated with the response to imatinib. Haplotype analysis of XPC showed that the wild-type haplotype (499C-939A) was associated with a better response to imatinib. Moreover, the 5-year failure free survival for CA carriers was significantly better than that of the non-CA carriers (98% vs. 73%; P = 0.02). In the multivariate logistic model with genetic data and clinical covariates, the hemoglobin (Hb) level and the XPC haplotype were independently associated with the treatment response, with patients having a Hb ,11 g/dl (Odds ratio [OR] = 5.0, 95% confidence interval [CI] = 1.5,16.1) or a non-CA XPC haplotype (OR = 4.1, 95% CI = 1.6,10.6) being at higher risk of suboptimal response/treatment failure. Our findings suggest that genetic polymorphisms in the NER pathway may influence the results to imatinib treatment in CML. Am. J. Hematol., 2010. © 2010 Wiley-Liss, Inc. [source] Dasatinib 140 mg once daily versus 70 mg twice daily in patients with Ph-positive acute lymphoblastic leukemia who failed imatinib: Results from a phase 3 study,,AMERICAN JOURNAL OF HEMATOLOGY, Issue 3 2010Michael B. Lilly Dasatinib 70 mg twice daily is indicated for Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) intolerant or resistant to imatinib. In patients with chronic-phase chronic myelogenous leukemia, once-daily dosing has similar efficacy with improved safety, compared with twice-daily dosing. A phase 3 study (n = 611) assessed the efficacy and safety of dasatinib 140 mg once daily versus 70 mg twice-daily in patients with advanced phase chronic myelogenous leukemia or Ph+ ALL resistant or intolerant to imatinib. Here, results from the Ph+ ALL subset (n = 84) with a 2-year follow-up are reported. Patients were randomly assigned to receive dasatinib either 140 mg once daily (n = 40) or 70 mg twice daily (n = 44). The rate of confirmed major hematologic response with once-daily dosing (38%) was similar to that with twice-daily dosing (32%). The rate of major cytogenetic response with once-daily dosing (70%) was higher than that with twice-daily dosing (52%). Compared with the twice-daily schedule, the once-daily schedule had longer progression-free survival (median, 3.0 months versus 4.0 months, respectively) and shorter overall survival (median, 9.1 months versus 6.5 months, respectively). Overall safety profiles were similar between two groups, with nonhematologic adverse events being mostly grade 1 or 2. Pleural effusion was less frequent with once-daily dosing than with twice-daily dosing (all grades, 18% versus 32%). Notably, none of the differences between the two schedules was statistically significant. Compared with the 70 mg twice daily, dasatinib 140 mg once daily had similar overall efficacy and safety in patients with imatinib-resistant or intolerant Ph+ ALL. (clinicaltrials.gov identifier: NCT00123487). Am. J. Hematol. 2010. © 2009 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||||||||