Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ki11502 is a novel multitargeted receptor tyrosine kinase (RTK) inhibitor with selectivity against platelet-derived growth factor receptor alpha/beta (PDGFRalpha/beta). Ki11502 (0.1-1 nM, 2 days) profoundly caused growth arrest, G(0)/G(1) cell-cycle arrest, and apoptosis associated with down-regulation of Bcl-2 family proteins in the eosinophilic leukemia EOL-1 cells having the activated FIP1-like 1/PDGFRalpha fusion gene. Ki11502 decreased levels of p-PDGFRalpha and its downstream signals, including p-Akt, p-ERK, and p-STAT5, in EOL-1 cells. Of note, Ki11502 was also active against imatinib-resistant PDGFRalphaT674I mutant. In addition, Ki11502 inhibited proliferation of biphenotipic leukemia MV4-11 and acute myelogenous leukemia MOLM13 and freshly isolated leukemia cells having activating mutations in FMS-like tyrosine kinase 3 (FLT3). This occurred in parallel with the drug inhibiting FLT3 and its downstream signal pathways, as measured by fluorescence-activated cell sorting using the phospho-specific antibodies. In addition, Ki11502 totally inhibited proliferation of EOL-1 cells growing as tumor xenografts in SCID mice without any noticeable adverse effects. Taken together, Ki11502 has profound antiproliferative effects on select subsets of leukemia including those possessing imatinib-resistant mutation.
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PMID:Ki11502, a novel multitargeted receptor tyrosine kinase inhibitor, induces growth arrest and apoptosis of human leukemia cells in vitro and in vivo. 1830 36

(1) Imatinib, a tyrosine kinase inhibitor, was first marketed for the treatment of chronic myeloid leukaemia and some gastrointestinal stromal tumours. Its indications have gradually expanded over the years. (2) There is no consensus treatment for adults with Philadelphia chromosome-positive acute lymphoblastic leukaemia. In a trial comparing imatinib versus chemotherapy as initial treatment for 55 patients, the haematological response rate was higher with imatinib. Non-comparative trials provided haematological response rates of about 90%, but it is not known whether or not this translates into a survival advantage. In three non-comparative trials including patients with relapsed or refractory disease after chemotherapy, 50% of patients showed a survival time of at least 7 months. In the absence of any direct comparisons, we do not know if this represents an improvement over the results obtained with the best palliative care. (3) The only potential cure for myelodysplastic syndromes is allogeneic haematopoietic stem cell transplantation but this is not always feasible. Some myelodysplastic syndromes are associated with myeloproliferation and PDGFR gene rearrangements; imatinib is the first drug available for these patients. The manufacturer has compiled data on 55 patients treated with imatinib. Most patients had a favourable haematological response, but no survival data were published. (4) The severity of the hypereosinophilic syndrome is highly variable. Forms associated with FIP1L1-PDGFRalpha gene rearrangements have a poor prognosis. Clinical evaluation of imatinib in this setting is based on a compilation of data concerning 176 treated patients. The haematological response rate was high in patients with the mutant gene, but it is not known whether this translated into increased survival. (5) Dermatofibrosarcoma protuberans is a rare form of mainly localised skin cancer. Treatment is based on surgical excision but relapses are frequent. In one series, 9 out of 12 patients treated with imatinib had at least a partial tumour response, making surgical excision possible in 3 cases. (6) Imatinib has diverse and frequent adverse effects; nausea and vomiting, oedema, fluid retention, cutaneous disorders and heart failure. There is some evidence pointing to a risk of urologic cancers and altered bone metabolism.
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PMID:Imatinib: new indication. New indications, but not robust evidence. 1862 99

The year 2008 marks the fifth anniversary since the publication which identified the FIP1L1-PDGFRA fusion gene in patients with idiopathic hypereosinophilia. With the benefit of time, a more comprehensive picture has emerged regarding several characteristics of the fusion, including its incidence, biological features and the clinical profile of patients who carry the molecular rearrangement. A few prospective trials have now better defined the natural history of imatinib-treated FIP1L1-PDGFRA-positive patients, from which some basic conclusions can be drawn: the prognosis is outstanding, acquired resistance is exceedingly rare, but ongoing imatinib treatment is likely required to prevent relapse. The emergence of genetically assigned eosinophilias has led the World Health Organization in 2008 to adopt a semi-molecular classification scheme, with one subcategory named 'myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA, PDGFRB or FGFR1.' Molecular rearrangements involving other partner genes, such as ETV6 and JAK2, have also been associated with eosinophilic disorders, and will likely be assimilated into such classifications over time. Despite the molecularly defined eosinophilias comprising a small proportion of cases compared to the aggregate of other subtypes of hypereosinophilia, their recognition is critical because of the availability of highly effective molecularly targeted therapy.
Leukemia 2008 Nov
PMID:Five years since the discovery of FIP1L1-PDGFRA: what we have learned about the fusion and other molecularly defined eosinophilias. 1884 83

This study evaluated the efficacy and safety of imatinib in chronic eosinophilic leukaemia (CEL, n = 23) and hypereosinophilic syndrome (HES, n = 13). In CEL with FIP1L1-PDGFRA (n = 16) or various PDGFRB fusion genes (n = 5), complete haematological remission (CHR) was achieved in 95% (20/21) after 3 months. Complete molecular remission (CMR) was seen in 75% (12/16) of cases with FIP1L1-PDGFRA positive CEL by 6 months, and in 87% (13/15) after 12 months. CMR was achieved in three of five PDGFRB fusion positive patients after 3, 9 and 18 months respectively. All patients are currently on imatinib (100 mg; n = 13, 400 mg; n = 8) and no molecular relapse has yet been observed (median 26.7 months; range, 6.9-39.9). Imatinib was less effective in HES and CEL without known molecular aberration (n = 15); CHR was observed in 40% (6/15) of patients, two patients relapsed after 4.8 and 24.5 months. Three patients died due to imatinib-resistant progressive CEL (n = 2) or myocardial infarction (n = 1) unrelated to study treatment. Overall, imatinib was well tolerated with a low incidence of grade III/IV toxicities. These data confirmed the long-term efficacy of imatinib for PDGFR-rearranged CEL patients, and also showed that a minority of HES cases without known molecular aberrations may benefit from imatinib.
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PMID:Safety and efficacy of imatinib in chronic eosinophilic leukaemia and hypereosinophilic syndrome: a phase-II study. 1912 Mar 52

To evaluate current detection methods for FIP1L1-PDGFRA in hypereosinophilic syndrome (HES), we developed a means to rapidly amplify genomic break points. We screened 202 cases and detected genomic junctions in all samples previously identified as RT-PCR positive (n=43). Genomic fusions were amplified by single step PCR in all cases whereas only 22 (51%) were single step RT-PCR positive. Importantly, FIP1L1-PDGFRA was detected in two cases that initially tested negative by RT-PCR or fluorescence in situ hybridization. Absolute quantitation of the fusion by real-time PCR from genomic DNA (gDNA) using patient-specific primer/probe combinations at presentation (n=13) revealed a 40-fold variation between patients (range, 0.027-1.1 FIP1L1-PDGFRA copies/haploid genome). In follow up samples, quantitative analysis of gDNA gave 1-2 log greater sensitivity than RQ-PCR of cDNA. Minimal residual disease assessment using gDNA showed that 11 of 13 patients achieved complete molecular response to imatinib within a median of 9 months (range, 3-17) of starting treatment, with a sensitivity of detection of up to 1 in 10(5). One case relapsed with an acquired D842V mutation. We conclude that detection of FIP1L1-PDGFRA from gDNA is a useful adjunct to standard diagnostic procedures and enables more sensitive follow up of positive cases after treatment.
Leukemia 2009 Feb
PMID:Detection and molecular monitoring of FIP1L1-PDGFRA-positive disease by analysis of patient-specific genomic DNA fusion junctions. 1898 50

The FIP1L1-PDGFRA fusion gene is a recurrent molecular abnormality in patients with eosinophilia-associated myeloproliferative neoplasms. We characterized FIP1L1-PDGFRA junction sequences from 113 patients at the mRNA (n=113) and genomic DNA (n=85) levels. Transcript types could be assigned in 109 patients as type A (n=50, 46%) or B (n=47, 43%), which were created by cryptic acceptor splice sites in different introns of FIP1L1 (type A) or within PDGFRA exon 12 (type B). We also characterized a new transcript type C (n=12, 11%) in which both genomic breakpoints fell within coding sequences creating a hybrid exon without use of a cryptic acceptor splice site. The location of genomic breakpoints within PDGFRA and the availability of AG splice sites determine the transcript type and restrict the FIP1L1 exons used for the creation of the fusion. Stretches of overlapping sequences were identified at the genomic junction site, suggesting that the FIP1L1-PDGFRA fusion is created by illegitimate non-homologous end-joining. Statistical analyses provided evidence for clustering of breakpoints within FIP1L1 that may be related to DNA- or chromatin-related structural features. The variability in the anatomy of the FIP1L1-PDGFRA fusion has important implications for strategies to detect the fusion at diagnosis or for monitoring response to treatment.
Leukemia 2009 Feb
PMID:The molecular anatomy of the FIP1L1-PDGFRA fusion gene. 1898 51

Therapeutically validated oncoproteins in myeloproliferative neoplasms (MPNs) include BCR-ABL in chronic myelogenous leukemia (CML) and a spectrum of PDGFRA/B mutant proteins that are products of intra- (eg, FIP1L1-PDGFRA) or interchromosomal (eg, ETV6-PDGFRB) gene fusions. Other MPN-relevant putative oncogenes that are awaiting therapeutic validation, include JAK2 and MPL mutations in polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF); KITD816V and other KIT mutations in systemic mastocytosis, and FGFR1 rearrangements associated with the 8p11 leukemia/lymphoma syndrome. The current review focuses on mutant molecules of interest in classic MPNs (ie, CML, PV, ET, and PMF) in the context of their value as drug targets.
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PMID:Oncogenic signals as treatment targets in classic myeloproliferative neoplasms. 1914 89

Although leukemogenic tyrosine kinases (LTKs) activate a common set of downstream molecules, the phenotypes of leukemia caused by LTKs are rather distinct. Here we report the molecular mechanism underlying the development of hypereosinophilic syndrome/chronic eosinophilic leukemia by FIP1L1-PDGFRalpha. When introduced into c-Kit(high)Sca-1(+)Lineage(-) cells, FIP1L1-PDGFRalpha conferred cytokine-independent growth on these cells and enhanced their self-renewal, whereas it did not immortalize common myeloid progenitors in in vitro replating assays and transplantation assays. Importantly, FIP1L1-PDGFRalpha but not TEL-PDGFRbeta enhanced the development of Gr-1(+)IL-5Ralpha(+) eosinophil progenitors from c-Kit(high)Sca-1(+)Lineage(-) cells. FIP1L1-PDGFRalpha also promoted eosinophil development from common myeloid progenitors. Furthermore, when expressed in megakaryocyte/erythrocyte progenitors and common lymphoid progenitors, FIP1L1-PDGFRalpha not only inhibited differentiation toward erythroid cells, megakaryocytes, and B-lymphocytes but aberrantly developed eosinophil progenitors from megakaryocyte/erythrocyte progenitors and common lymphoid progenitors. As for the mechanism of FIP1L1-PDGFRalpha-induced eosinophil development, FIP1L1-PDGFRalpha was found to more intensely activate MEK1/2 and p38(MAPK) than TEL-PDGFRbeta. In addition, a MEK1/2 inhibitor and a p38(MAPK) inhibitor suppressed FIP1L1-PDGFRalpha-promoted eosinophil development. Also, reverse transcription-PCR analysis revealed that FIP1L1-PDGFRalpha augmented the expression of C/EBPalpha, GATA-1, and GATA-2, whereas it hardly affected PU.1 expression. In addition, short hairpin RNAs against C/EBPalpha and GATA-2 and GATA-3KRR, which can act as a dominant-negative form over all GATA members, inhibited FIP1L1-PDGFRalpha-induced eosinophil development. Furthermore, FIP1L1-PDGFRalpha and its downstream Ras inhibited PU.1 activity in luciferase assays. Together, these results indicate that FIP1L1-PDGFRalpha enhances eosinophil development by modifying the expression and activity of lineage-specific transcription factors through Ras/MEK and p38(MAPK) cascades.
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PMID:FIP1L1-PDGFRalpha imposes eosinophil lineage commitment on hematopoietic stem/progenitor cells. 1914 1

Therapeutically validated oncoproteins in myeloproliferative neoplasms (MPN) include BCR-ABL1 and rearranged PDGFR proteins. The latter are products of intra- (e.g. FIP1L1-PDGFRA) or inter-chromosomal (e.g. ETV6-PDGFRB) gene fusions. BCR-ABL1 is associated with chronic myelogenous leukaemia (CML) and mutant PDGFR with an MPN phenotype characterized by eosinophilia and in addition, in case of FIP1L1-PDGFRA, bone marrow mastocytosis. These genotype-phenotype associations have been effectively exploited in the development of highly accurate diagnostic assays and molecular targeted therapy. It is hoped that the same will happen in other MPN with specific genetic alterations: polycythemia vera (JAK2 V617F and other JAK2 mutations), essential thrombocythemia (JAK2V617F and MPL515 mutations), primary myelofibrosis (JAK2 V617F and MPL515 mutations), systemic mastocytosis (KITD816V and other KIT mutations) and stem cell leukaemia/lymphoma (ZNF198-FGFR1 and other FGFR1 fusion genes). The current review discusses the above listed mutant molecules in the context of their value as drug targets.
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PMID:Molecular drug targets in myeloproliferative neoplasms: mutant ABL1, JAK2, MPL, KIT, PDGFRA, PDGFRB and FGFR1. 1917 93

Chronic eosinophilic leukemia (CEL) is a rare myeloproliferative neoplasm characterized by the FIP1L1-PDGFRA fusion gene, variant PDGFRA fusions or other genetic lesions. Most FIP1L1-PDGFRA positive patients enjoy durable and complete molecular responses to low-dose imatinib (Glivec/Gleevec). However, resistance mediated by a T674I mutation in the ATP-binding pocket of PDGFRA has been reported in advanced disease, and sorafenib, a potent inhibitor of RAF-1, B-RAF, VEGFR and PDGFR, is active against this mutant in vitro. We describe a case of FIP1L1-PDGFRalpha T674I CEL in blast crisis that responded to sorafenib (Nexavar). However, this clinical response was short-lived because of the rapid emergence of a FIP1L1-PDGFRalpha D842V mutant. An N-Nitroso-N-ethylurea-mutagenesis screen indeed identified this mutant as a major sorafenib-resistant mutant. In vitro, the novel FIP1L1-PDGFRalpha D842V mutant is highly resistant to sorafenib, imatinib, dasatinib (Sprycell) and PKC412 (Midostaurin). Thus, sorafenib is clinically active in imatinib-resistant FIP1L1-PDGFRalpha T674I CEL, but the rapid emergence of other mutants may limit the response duration. The identification of new PDGFR inhibitors will be required to overcome resistance by this D842V mutant.
Leukemia 2009 May
PMID:FIP1L1-PDGFRalpha D842V, a novel panresistant mutant, emerging after treatment of FIP1L1-PDGFRalpha T674I eosinophilic leukemia with single agent sorafenib. 1921 37


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