Prevalence and Prognostic Significance of FLT3 Mutations in Acute Myeloid Leukemia: Association of ITDs with Poor Outcome in Patients with Normal Cytogenetics.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2017-2017
Author(s):  
Michela Palmisano ◽  
Emanuela Ottaviani ◽  
Tiziana Grafone ◽  
Nicoletta Testoni ◽  
Stefania Paolini ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Myeloid Leukemia ◽  
Prognostic Impact ◽  
Wild Type ◽  
Poor Prognostic Factor ◽  
Flt3 Mutations ◽  
Blast Cells ◽  
Normal Cytogenetics ◽  
Acute Myeloid

Abstract Acute Myeloid Leukemia (AML) is a difficult disease to treat, and better treatments are needed. Molecular targeted therapy represents a novel therapeutic approach. Activating mutations of FMS-like tyrosine kinase 3 (FLT3) are present in approximately one third of patients with de novo AML and have been implicated in its pathogenesis. The leukemic blasts of most AML patients have the internal tandem duplications (ITDs) in the juxtamembrane region or point mutations in Asp835 and Iso836 codons in the activation loop of the kinase domain (TKD) of the FLT3 receptor. Both mutations result in constitutive FLT3 receptor activity and may play a significant role in leukemogenesis. In this study we have analyzed the incidence and type of FLT3 mutations in a large series of newly diagnosed AML patients. Furthermore, we have evaluated the prognostic impact of FLT3 mutations. The FLT3/ITD was determined by polymerase chain reaction (PCR). The mutations of D835 and I836 codons were determined by PCR followed by restriction enzyme digestion (PCR-RFLP). For the estimation of the statistic significance of the differences in the clinical-biological characteristics, between the mutated patients and wild-type patients, it has been used the Student’s test t for independent data. The probabilities of overall survival (OS) and disease free survival (DFS) were analysed by Kaplan-Meier method; the differences of OS and DFS, between the mutated patients and wild-type patients, were assessed using the log-rank test. Both FLT3/ITD and FLT3/TKD mutations were found in 15%. Dual mutations were found in 2% of 126 patients. Among the FAB subtypes of AML, the rate of FLT3 aberrations was higher in M4 (27%) and M5 (26%). FLT3/ITD was associated to leukocytosis (106.8x10(e)9/l vs 30x10(e)9/l in FLT3-wt, p=0.015) and high percentage of circulating blast cells (82% vs 42% in FLT3-wt, p<0.0001). Differently, FLT3/TKD mutations were not associated with high white blood cells count and blast cells percentage. FLT3 mutations were more prevalent in patients with normal karyotype (51%). In this group, DFS and OS were significantly inferior for patients with FLT3/ITD than patients withouth mutations (0 vs 5, p=0.0032; 5 vs 9, p=0.049, respectively). We have identified the FLT3/ITD as an independent poor prognostic factor in AML patients with normal cytogenetics. Therefore, targeting FLT3 mutations represents a potential therapeutic target for AML. These results suggest that new treatment modalities, such as therapy with a FLT3 tyrosine kinase inhibitor, are clearly needed for this group of patients with “standard risk” profile.

Recent advances in FLT3 inhibitors for acute myeloid leukemia

2020 ◽  
Vol 12 (10) ◽  
pp. 961-981 ◽  
Author(s):  
Lexian Tong ◽  
Xuemei Li ◽  
Yongzhou Hu ◽  
Tao Liu
Keyword(s):  
Acute Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Myeloid Leukemia ◽  
Clinical Stage ◽  
Wild Type ◽  
New Techniques ◽  
Flt3 Mutations ◽  
Flt3 Inhibitors ◽  
Target Activity ◽  
Acute Myeloid

Fms-like tyrosine kinase-3 (FLT3) mutations occur in approximately 30% of acute myeloid leukemia (AML) cases, suggesting FLT3 as an attractive target for AML treatment. Early FLT3 inhibitors enhance antileukemia efficacy by inhibiting multiple targets, and thus had stronger off-target activity, increasing their toxicity. Recently, a number of potent and selective FLT3 inhibitors have been developed, many of which are effective against multiple mutations. This review outlines the evolution of AML-targeting FLT3 inhibitors by focusing on their chemotypes, selectivity and activity over FLT3 wild-type and FLT3 mutations as well as new techniques related to FLT3. Compounds that currently enter the late clinical stage or have entered the market are also briefly reported.

FLT3 mutations have no prognostic impact in elderly patients with acute myeloid leukemia and normal karyotype

2009 ◽  
Vol 84 (8) ◽  
pp. 532-534 ◽  
Author(s):  
Felicetto Ferrara ◽  
Clelia Criscuolo ◽  
Cira Riccardi ◽  
Tiziana Izzo ◽  
Mariangela Pedata ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Elderly Patients ◽  
Myeloid Leukemia ◽  
Normal Karyotype ◽  
Prognostic Impact ◽  
Flt3 Mutations ◽  
Acute Myeloid

scholarly journals Targeted Treatment of FLT3 -Overexpressing Acute Myeloid Leukemia with MiR-150 Nanoparticles Guided By Conjugated FLT3 Ligand Peptides

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 3784-3784
Author(s):  
Xi Jiang ◽  
Jason Bugno ◽  
Chao Hu ◽  
Yang Yang ◽  
Tobias Herold ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Median Survival ◽  
Myeloid Leukemia ◽  
Poor Prognosis ◽  
Prognostic Impact ◽  
Dependent Manner ◽  
Flt3 Ligand ◽  
Acute Myeloid

Abstract Acute myeloid leukemia (AML) is one of the most common and fatal forms of hematopoietic malignancies. With standard chemotherapies, only 30-50% of younger (aged <60) and 5-10% of older patients with AML survive longer than 5 years. Aberrancy of FMS-like tyrosine kinase 3 (FLT3) occurs in the majority cases of AML. Two major classes of constitutively activating mutations of FLT3, i.e. internal-tandem duplications (ITDs) and tyrosine kinase domain (TKD) point mutations are found in more than 30% of AML cases and usually predict poor prognosis. Overexpression of FLT3 has also been reported in more than 70% of AML cases with a variety of AML subtypes, e.g. MLL (Mixed Lineage Leukemia)-rearranged or FLT3 -ITD AML, and may be associated with poor survival in AML patients. Given the disappointing results with FLT3 tyrosine kinase inhibitors (TKIs) in clinical trials in the past decade, decreasing the overall abundance of FLT3 at the RNA and protein levels would be an alternative strategy to treat AMLs with FLT3 overexpression and/or FLT3 -ITD/TKD mutations. MicroRNAs (miRNA) are a class of small, non-coding RNAs that play important roles in post-transcriptional gene regulation. We recently reported that miR-150 functions as a pivotal tumor-suppressor gatekeeper in MLL-rearranged and other subtypes of AML, through targeting FLT3 and MYB directly, and the MYC/LIN28/HOXA9/MEIS1 pathway indirectly. Our data showed that MLL-fusion proteins up-regulate FLT3 level through inhibiting the maturation of miR-150. Therefore, our findings strongly suggest a significant clinical potential of restoration of miR-150 expression/function in treating FLT3 -overexpressing AML. In the present study, we first analyzed FLT3 expression patterns and prognostic impact in a large cohort of AML patients (n=562). We found that FLT3 is aberrantly highly expressed in FAB M1/M2/M5 AML or AML with t(11q23)/MLL -rearrangements, FLT3 -ITD or NPM1 mutations, and that increased expression of FLT3 is an independent predictor of poor prognosis in patients with FLT3 -overexpressing AML. To treat FLT3 -overexpressing AML, we developed a novel targeted nanoparticle system consisting of FLT3 ligand (FLT3L)-conjugated G7 poly(amidoamine) (PAMAM) dendriplexes encapsulating miR-150 oligos (see Figure 1A). In FLT3 -overexpressing cell lines, the uptake ratios of the G7-FLT3L dendrimers were much higher (50.3~97.1%) than the G7-histone 2B (H2B) control nanoparticles (4.3~33.2%). And the uptake only took minutes. By integrating the miR-150 oligo with G7-FLT3L dendrimers, we constructed the G7-FLT3L-miR-150 dendriplexes, which significantly reduced the viability and increased the apoptosis of MONOMAC-6 cells carrying t(9;11) in a dose-dependent manner. To increase the stability of miR-150 oligos, we incorporated a 2'-o -methyl (2'-O Me) modification into the miRNA oligos. Indeed, the G7-FLT3L nanoparticles carrying 2'-O Me modified miR-150 exhibited a more sustained inhibition on cell growth. In order to further investigate the in vivo therapeutic effects of the miR-150 nanoparticles, we used a MLL -rearranged leukemia model. We transplanted wild-type recipient mice with primary mouse leukemic cells bearing the MLL-AF9 fusion. After the onset of leukemia, the mice were treated with G7-Flt3L or G7-NH2 control nanoparticles complexed with 2'-O Me-modified miR-150 oligos. In these treated animals, G7-Flt3L-miR-150 nanoparticles tended to be enriched in the bone marrow. The G7-Flt3L-miR-150 nanoparticles showed the best therapeutic effect (with median survival of 86 days), as compared with the control group (Ctrl; PBS treated; with median survival of 54 days) or the G7-NH2-miR-150 treated group (with median survival of 63 days). Nanoparticles carrying miR-150 mutant oligos showed no anti-leukemia effect at all. Notably, the G7-Flt3L-miR-150 treatment almost completely blocked MLL-AF9 -induced leukemia in 20% of the mice (Fig. 1B). Furthermore, the G7-Flt3L-miR-150 nanoparticles showed a synergistic effect with JQ1, a small-molecule inhibitor of the MYC pathway, in treating AML in vivo (Fig. 1C). Collectively, we have developed a novel targeted therapeutic strategy to treat FLT3-overexpressing AML, such as MLL-rearranged leukemias, which are resistant to currently available therapies, with both high specificity and efficacy. Disclosures No relevant conflicts of interest to declare.

Activating FLT3 Mutations Display a Wide Range Of Transforming Potential and a Characteristic Pathway Profile Associated With Prognosis In Acute Myeloid Leukemia

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1312-1312
Author(s):  
Hanna Janke ◽  
Friederike Schneider ◽  
Daniela Schumacher ◽  
Tobias Herold ◽  
Hopfner Karl-Peter ◽  
...  
Keyword(s):  
Gene Expression ◽  
Acute Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Gene Expression Profile ◽  
Myeloid Leukemia ◽  
Normal Karyotype ◽  
Wide Range ◽  
Flt3 Mutations ◽  
Acute Myeloid

Abstract Background Internal tandem duplication (ITD) and pointmutations in the tyrosine kinase domain (TKD) of the receptor tyrosine kinase FLT3 occur in about 30% of patients with acute myeloid leukemia (AML). In contrast to the negative prognostic impact of FLT3-ITD in normal karyotype AML, FLT3 pointmutations occurring in the TKD and juxtamembrane (JM) region are less frequent and of unclear clinical impact. Although TKD mutations can induce resistance to tyrosine kinase inhibitors the individual transforming potential of FLT3 pointmutations has not been analysed in detail. In this study we have performed a comprehensive analysis of various FLT3 mutants in a comparative setting in vitro and analyzed gene expression profiles, and clinical outcome with respect to FLT3mutation status. Material and Methods We analyzed relapse and survival in 672 cytogenetically normal AML patients and the FLT3 status at diagnosis and relapse in 156 patients. In the murine Ba/F3 cell model we analyzed the transforming potential, subcellular localization, phosphorylation status and signaling properties of eight different FLT3 mutants. The investigated FLT3 mutations include three ITD of different length and insertion site, V592A in the JM region, common FLT3-TKD mutations D835V and D835Y as well as D839G and I867S in the second TKD. FLT3-D839G and -I867S were recently found in AML patients by our group during routine diagnostics but have not been functionally characterized before. The corresponding remission samples did not express these mutations. Further a gene expression profile analysis with respect to FLT3-ITD and -TKD mutation status and evaluation of differences in activation of predefined STAT5 target gene set was performed. Results In 672 normal karyotype AML patients FLT3-ITD, but not FLT3-TKD mutations were associated with an inferior relapse free and overall survival in multivariate analysis. In paired diagnosis-relapse samples FLT3-ITD showed higher stability (70%) compared to FLT3-TKD (30%). In vitro, FLT3-ITD induced a fully transformed phenotype in Ba/F3 cells, whereas FLT3 pointmutations showed a weaker but clearly transformed phenotype with gradual increase in proliferation and protection from apoptosis. The transforming capacity of the investigated mutants was associated with cell surface expression and tyrosine 591 phosphorylation of the FLT3 receptor. Western blot experiments revealed STAT5 activation only in FLT3-ITD transformed cells, further gene expression profile analyses displayed differences in predefined STAT5 target genes between FLT3-ITD and FLT3-TKD mutations. In contrast, FLT3-non-ITD mutants had an enhanced signal of AKT and MAPK activation. Further differences were found on mRNA level presenting deregulation of SOCS2, ENPP2, PRUNE2 and ART3 expression between FLT3-ITD, FLT3-TKD and FLT3-WT. Conclusion Although apparently divergent in response to treatment all functionally characterized mutants showed a clear gain-of-function phenotype with a wide range of transforming activity associated with clinical prognosis and signaling. Disclosures: No relevant conflicts of interest to declare.

Flt3 mutations from patients with acute myeloid leukemia induce transformation of 32D cells mediated by the Ras and STAT5 pathways

Blood ◽  
2000 ◽  
Vol 96 (12) ◽  
pp. 3907-3914 ◽  
Author(s):  
Masao Mizuki ◽  
Regina Fenski ◽  
Hartmut Halfter ◽  
Itaru Matsumura ◽  
Rainer Schmidt ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Colony Formation ◽  
Myeloid Leukemia ◽  
Map Kinases ◽  
Rapid Development ◽  
Dominant Negative ◽  
Wild Type ◽  
Flt3 Mutations ◽  
Induced Apoptosis ◽  
Acute Myeloid

Somatic mutations of the receptor tyrosine kinase Flt3 consisting of internal tandem duplications (ITD) occur in 20% of patients with acute myeloid leukemia. They are associated with a poor prognosis of the disease. In this study, we characterized the oncogenic potential and signaling properties of Flt3 mutations. We constructed chimeric molecules that consisted of the murine Flt3 backbone and a 510-base pair human Flt3 fragment, which contained either 4 different ITD mutants or the wild-type coding sequence. Flt3 isoforms containing ITD mutations (Flt3-ITD) induced factor-independent growth and resistance to radiation-induced apoptosis in 32D cells. Cells containing Flt3-ITD, but not those containing wild-type Flt3 (Flt3-WT), formed colonies in methylcellulose. Injection of 32D/Flt3-ITD induced rapid development of a leukemia-type disease in syngeneic mice. Flt3-ITD mutations exhibited constitutive autophosphorylation of the immature form of the Flt3 receptor. Analysis of the involved signal transduction pathways revealed that Flt3-ITD only slightly activated the MAP kinases Erk1 and 2 and the protein kinase B (Akt) in the absence of ligand and retained ligand-induced activation of these enzymes. However, Flt3-ITD led to strong factor-independent activation of STAT5. The relative importance of the STAT5 and Ras pathways for ITD-induced colony formation was assessed by transfection of dominant negative (dn) forms of these proteins: transfection of dnSTAT5 inhibited colony formation by 50%. Despite its weak constitutive activation by Flt3-ITD, dnRas also strongly inhibited Flt3-ITD–mediated colony formation. Taken together, Flt3-ITD mutations induce factor-independent growth and leukemogenesis of 32D cells that are mediated by the Ras and STAT5 pathways.

CEBPA Mutations in Younger Adults With Acute Myeloid Leukemia and Normal Cytogenetics: Prognostic Relevance and Analysis of Cooperating Mutations

2004 ◽  
Vol 22 (4) ◽  
pp. 624-633 ◽  
Author(s):  
Stefan Fröhling ◽  
Richard F. Schlenk ◽  
Ina Stolze ◽  
Jörg Bihlmayr ◽  
Axel Benner ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Hazard Ratio ◽  
Younger Adults ◽  
Prognostic Relevance ◽  
Remission Duration ◽  
Flt3 Mutations ◽  
Cebpa Mutations ◽  
Normal Cytogenetics ◽  
Acute Myeloid

Purpose To assess the prognostic relevance of mutations in the CEBPA gene encoding CCAAT/enhancer binding protein alpha (C/EBPα) in a large prospective series of younger adults with acute myeloid leukemia (AML) and normal cytogenetics. Patients and Methods The entire CEBPA coding region was sequenced in diagnostic samples from 236 AML patients 16 to 60 years of age with normal cytogenetics who were uniformly treated on two consecutive protocols of the AML Study Group Ulm, and CEBPA mutation status was correlated with clinical outcome. Results CEBPA mutations were detected in 36 (15%) of 236 patients. Twenty-one (9%) of 236 patients had mutations predicted to result in loss of C/EBPα function. Remission duration and overall survival (OS) were significantly longer for the 36 patients with CEBPA mutations (P = .01 and P = .05, respectively). On multivariate analysis, wild-type CEBPA was an independent prognostic marker affecting remission duration (hazard ratio, 2.85; P = .01) and OS (hazard ratio, 1.87; P = .04). Analysis of cooperating mutations (both types of activating FLT3 mutations and MLL partial tandem duplications) showed that FLT3 mutations had no significant prognostic influence in patients with CEBPA mutations. Furthermore, there was no significant overlap between the subgroup of patients with CEBPA mutation with predicted loss of C/EBPα function and patients with FLT3 or MLL mutations, suggesting that CEBPA loss-of-function mutations define a distinct biologic subclass of AML with normal cytogenetics. Conclusion Mutant CEBPA predicts favorable prognosis and may improve risk stratification in AML patients with normal cytogenetics.

scholarly journals Frequency and prognostic impact of mutations in SRSF2, U2AF1, and ZRSR2 in patients with myelodysplastic syndromes

Blood ◽  
2012 ◽  
Vol 119 (15) ◽  
pp. 3578-3584 ◽  
Author(s):  
Felicitas Thol ◽  
Sofia Kade ◽  
Carola Schlarmann ◽  
Patrick Löffeld ◽  
Michael Morgan ◽  
...  
Keyword(s):  
Overall Survival ◽  
Acute Myeloid Leukemia ◽  
Confidence Interval ◽  
Myelodysplastic Syndromes ◽  
Myeloid Leukemia ◽  
Univariate Analysis ◽  
Hazard Ratio ◽  
Prognostic Impact ◽  
Wild Type ◽  
Acute Myeloid

Abstract Mutations in genes of the splicing machinery have been described recently in myelodysplastic syndromes (MDS). In the present study, we examined a cohort of 193 MDS patients for mutations in SRSF2, U2AF1 (synonym U2AF35), ZRSR2, and, as described previously, SF3B1, in the context of other molecular markers, including mutations in ASXL1, RUNX1, NRAS, TP53, IDH1, IDH2, NPM1, and DNMT3A. Mutations in SRSF2, U2AF1, ZRSR2, and SF3B1 were found in 24 (12.4%), 14 (7.3%), 6 (3.1%), and 28 (14.5%) patients, respectively, corresponding to a total of 67 of 193 MDS patients (34.7%). SRSF2 mutations were associated with RUNX1 (P < .001) and IDH1 (P = .013) mutations, whereas U2AF1 mutations were associated with ASXL1 (P = .005) and DNMT3A (P = .004) mutations. In univariate analysis, mutated SRSF2 predicted shorter overall survival and more frequent acute myeloid leukemia progression compared with wild-type SRSF2, whereas mutated U2AF1, ZRSR2, and SF3B1 had no impact on patient outcome. In multivariate analysis, SRSF2 remained an independent poor risk marker for overall survival (hazard ratio = 2.3; 95% confidence interval, 1.28-4.13; P = .017) and acute myeloid leukemia progression (hazard ratio = 2.83; 95% confidence interval, 1.31-6.12; P = .008). These results show a negative prognostic impact of SRSF2 mutations in MDS. SRSF2 mutations may become useful for clinical risk stratification and treatment decisions in the future.

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