Blast Transformation in a Patient with Primary Myelofibrosis Initiated from JAK2 V617F Progenitor.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4665-4665 ◽  
Author(s):  
Sabina I. Swierczek ◽  
Donghoon Yoon ◽  
Josef T. Prchal
Keyword(s):  
X Chromosome ◽  
Real Time Pcr ◽  
De Novo ◽  
Jak2 V617f ◽  
Primary Myelofibrosis ◽  
Jak2 V617f Mutation ◽  
Quantitative Real Time Pcr ◽  
Leukemic Transformation ◽  
Cd34 Cells ◽  
V617f Mutation

Abstract Myeloproliferative disorders (MPDs) are caused by clonal proliferation arising from a single multi-lineage stem cell. The JAK2 V617F mutation has been reported in greater than 90% of patients with polycythemia vera (PV), and ∼50% of patients with essential thrombocythemia (ET) and primary myelofibrosis (PMF). However, several studies have indicated that the JAK2 V617F mutation is not an MPD initiating mutation but rather represents clonal evolution of these MPDs. Jelinek and colleagues first reported that most PV transformed acute leukemias are JAK2 V617F negative (Jelinek, Blood, 2005 106:3370). More recently, the role of the JAK2 V617F mutation in leukemic transformation in 27 patients with MPDs revealed that most JAK2 V617F -positive MPD patients transformed to a JAK2 V617F -negative AML (Theocharides, Blood, 2007 110:375); however, in the 4 patients with an apparent JAK2 V617F -positive leukemia clonality of leukemic blasts and mature granulocytes was not determined. Two models proposed by Theocharides et al may explain these findings. First, MPD and AML represent 2 independent clones that arose de novo from different progenitors. Second, MPD and AML are 2 subclones derived from a common progenitor. Here, we describe a woman with PMF with transformation to AML. We determined her JAK2 V617F mutation status by sensitive and quantitative real-time PCR (Nussenzveig, Exp Hematol, 2007 3:32). At the time of her transformation to AML, her normal appearing peripheral blood granulocytes were purified and the frequency of mutant JAK2 allele T was 6%. However, all FACS-sorter isolated CD34+ cells (enriched to 95% purity) were heterozygous for the JAK2 V617F mutation. To determine if MPD and AML clones arose de novo or from the same progenitor, we performed clonality studies using a newly developed sensitive and quantitative real-time PCR based on the X-chromosome inactivation principle using transcriptional clonality assays in granulocytes and CD34+ purified cells from peripheral blood at both stages of disease (see Swierczek et al, abstract, this meeting). When this woman’s PMF was first discovered, hematopoiesis was clonal, based on heterozygosity for three X-chromosome genes, FHL1, G6PD and IDS (Liu, Blood, 2003 101:3294) and their single allelic expression in granulocytes and platelets. At the time of leukemic transformation, both her granulocytes and leukemic CD34+ cells expressed all three identical isoforms from the same parental X chromosome. Our findings indicate that leukemic transformation does not invariably arise from a JAK2 V617F negative progenitor. This has important implication for therapy of MPDs with JAK2 V617F inhibitors, as these would not prevent leukemic transformation. It remains to be determined if the JAK2 background of leukemic progenitors is variable, and if there are differences between PV and PMF.

A High Sensitivity Detection Technique Reveals JAK2-V617F Mutation in Additional 20% of Patients with Essential Thrombocytemia, but Not in Patients with Primary Myelofibrosis, Considered Negative with a Conventional ASO-PCR

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2801-2801
Author(s):  
Francesca Bertolotti ◽  
Sarah Pozzi ◽  
Massimo Ulivi ◽  
Marina Podestà ◽  
Davide Imperiale ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
High Sensitivity ◽  
Jak2 V617f ◽  
Primary Myelofibrosis ◽  
Myeloproliferative Disorders ◽  
Jak2 V617f Mutation ◽  
The Real ◽  
V617f Mutation

Abstract Polycytemia Vera (PV), Essential Thrombocytemia (ET) and Primary Myelofibrosis (PMF) are defined as the major Philadelphia-negative myeloproliferative disorders (MPD). The JAK2-V617F gene mutation is a common feature of MPD but it is present in a variable proportion in patients: 95% of PV, 23 to 57% of ET and 30 to 57% of PMF patients. At the present, the most important role of JAK2-V617F mutation testing, over all during the initial evaluation of MPD patients, is that it can definitively confirm the diagnosis. In fact, its specificity permits to discriminate the considerable clinical overlap between reactive cellular proliferations and clonal myeloproliferative disorders. Moreover, because V617F is an acquired mutation that can be present in a small proportion of granulocytic populations, especially for ET, a highly sensitive detection method is essential. In fact, phenotypic effects ascribed to the presence of the JAK2-V617F mutation have been reported over all in studies with ET patients. Different sensitivity of various assays methods partially accounts for the wide range of mutation frequencies reported in literature for ET and PMF. Thus, to try to increase the sensitivity of JAK2 mutational status detection, we developed a Real-Time PCR technique that enhances allele discrimination between mutant and wild-type sequence. A Locked Nucleic Acid (LNA) clamping oligomer was added to the PCR reaction solution. In this macromolecules, the ribose moiety is modified with an extra bridge connecting the 2′ and 4′ carbons. The bridge “locks” the ribose in the 3′-end structural conformation. It binds preferentially the JAK2 wild type sequence preventing from polymerase elongation. The melting curve was used to analyse amplification products, avoiding post-PCR processing and supplying the diagnostic information immediately at the end of the amplification. 236 genomic DNA samples from healthy donors, ET and PMF patients were tested for JAK2-V617F mutation detection with a conventional allelespecific PCR (ASO-PCR, sensitivity: 1–3%). All samples were re-evaluated with a seminested PCR protocol and Real-Time PCR based method in order to improve the sensitivity. The cell line HEL DNA dilutions were used to assess the semi-nested PCR and the Real-Time PCR assay sensitivity level (0,1%). The frequency of JAK2-V617F point mutation increased from 52 to 72% in 168 ET samples. All results obtained with the new technique were confirmed by the semi-nested PCR protocol. In 58 PMF samples tested, 50% of patients were positive for the mutation in ASO-PCR while 55% resulted positive with the semi-nested protocol confirmed by the Real-Time PCR test. The high sensitivity in the JAK2-V617F mutation detection obtained with the semi-nested and the Real-Time PCR revealed that 20% of patients affected by ET and considered JAK2-V617F negative with a conventional ASO-PCR, were effectively positive. The comparison between three different analytical methods revealed that in ET but not in PMF patients, the mutation can be present only in a small proportion of granulocytic populations. Thus, since the prognostic relevance of V617F allele in ET, unlike in PMF, seems to be relevant, our high sensitive detection protocol can be effective for a correct molecular characterization and a diagnostic classification. The finding that a large proportion of ET patients bears a very small amount of JAK2-V617F mutated hematopoiesis further emphasizes the problem of the role of this small clone and warrants longitudinal analysis to understand whether this proportion remains stable or expands over time.

Frequency of the JAK2 Mutation and Its Usefulness as a Marker for Treatment Response and Disease Progression in Korean Patients with Chronic Myeloproliferative Disorders.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 4876-4876 ◽  
Author(s):  
Myung-Geun Shin ◽  
Hyeoung Joon Kim ◽  
Hye-Ran Kim ◽  
Sun-Young Lee ◽  
Il-Kwon Lee ◽  
...  
Keyword(s):  
Disease Progression ◽  
Treatment Response ◽  
Real Time ◽  
Real Time Pcr ◽  
Jak2 V617f ◽  
Jak2 V617f Mutation ◽  
Quantitative Real Time Pcr ◽  
Jak2 Mutation ◽  
Korean Patients ◽  
V617f Mutation

Abstract Background: The recent discovery of a single point mutation in the JAK2 gene (V617F) is a major advance in our understanding of the pathogenesis of BCR/ABL-negative chronic myeloproliferative disorders (CMPD). The frequency of the JAK2 V617F mutation in CMPD differs according to methods and research groups. We investigated the frequency of JAK2 mutations in Korean CMPD patients and demonstrated their usefulness as a new molecular marker for treatment response and disease progression in BCR/ABL-negative CMPD using quantitative real time PCR and pyrosequencing. Methods: Seventy-eight patients with BCR/ABL-negative CMPD comprising 42 cases of essential thrombocythemia (ET), 26 of polycythemia vera (PV), 7 with idiopathic myelofibrosis (MF), and 3 unclassifiable (UC) CMPD were enrolled in this study. A 364-bp PCR product containing the JAK2 V617F mutation was sequenced in both directions from total bone marrow cells. Restriction enzyme-based assessment with BsaXI was also used to search for JAK2 mutations. A quantitative real-time PCR-based allelic discrimination assay and pyrosequencing (Pyrosequencer PSQ96) were used to quantify the JAK2 V617F mutation status. Results: A single JAK2 V617F point mutation was identified in 20 (77%) of 26 patients with PV, 12 (26%) of 42 with ET, 7 (100%) of 7 with MF, and 2 (67%) of 3 with UC. The V617F mutation was present in over half of Korean patients with BCR/ABL-negative CMPD, giving an overall frequency of 53%. The proportion of mutant alleles ranged from 36 to 100% in the real-time PCR and pyrosequencing analysis. Patients with MF had a higher percentage of JAK2 mutant alleles than patients with ET (MF>PV>ET). PV patients (n=8) with a good response (phlebotomy only) had a relatively low proportion (58.9±20.1%) of the JAK2 mutant, while patients (n=9) showing a poor response (additional chemotherapy) initially had a higher proportion (76.6±19.0%; p=0.04185). Conclusion: The frequency of the JAK2 V617F mutation in Korean patients with PV was lower than that in reports from Western countries, although the overall frequency in Korean patients with BCR/ABL-negative CMPD was similar to previous reports. The results also suggest that the JAK2 mutation (quantification of JAK2 mutant alleles) can be used as a new marker for treatment response and disease progression in BCR/ABL-negative CMPD using quantitative real-time PCR or pyrosequencing.

JAK2 V617F mutational status predicts progression to large splenomegaly and leukemic transformation in primary myelofibrosis

Blood ◽  
2007 ◽  
Vol 110 (12) ◽  
pp. 4030-4036 ◽  
Author(s):  
Giovanni Barosi ◽  
Gaetano Bergamaschi ◽  
Monia Marchetti ◽  
Alessandro M. Vannucchi ◽  
Paola Guglielmelli ◽  
...  
Keyword(s):  
Jak2 V617f ◽  
Primary Myelofibrosis ◽  
Jak2 V617f Mutation ◽  
Confirmatory Test ◽  
Progression Rate ◽  
Homozygous Mutation ◽  
Leukemic Transformation ◽  
Jak2 Mutation ◽  
Mutational Status ◽  
V617f Mutation

Abstract Few investigators have evaluated the usefulness of the JAK2 V617F mutation for explaining the phenotypic variations and for predicting the risk of major clinical events in primary myelofibrosis (PMF). In a transversal survey we assayed by allele-specific polymerase chain reaction (PCR) the JAK2 V617F mutational status in 304 patients with PMF. Multiple DNA samples were collected prospectively from 64 patients, and a highly sensitive quantitative PCR was used as a confirmatory test. In a longitudinal prospective study we determined the progression rate to clinically relevant outcomes in 174 patients who had JAK2 mutation determined at diagnosis. JAK2 V617F was identified in 63.4% of patients. None of the V617F-negative patients who were sequentially genotyped progressed to become V617F positive, whereas progression rate from heterozygous to homozygous mutation was 10 per 100 patient-years. JAK2 V617F mutation contributed to hemoglobin, aquagenic pruritus, and platelet count variability, whereas homozygous mutation was independently associated with higher white blood cell count, larger spleen size, and greater need for cytoreductive therapies. Adjusting for conventional risk factors, V617F mutation independently predicted the evolution toward large splenomegaly, need of splenectomy, and leukemic transformation. We conclude that JAK2 V617F genotype should be considered in any future risk stratification of patients with PMF.

Evaluation of the JAK2 V617F gene mutation in myeloproliferative neoplasms cases: a one-center study from Eastern Anatolia

2019 ◽  
Vol 44 (4) ◽  
pp. 492-498
Author(s):  
Gonca Gulbay ◽  
Elif Yesilada ◽  
Mehmet Ali Erkurt ◽  
Harika Gozukara Bag ◽  
Irfan Kuku ◽  
...  
Keyword(s):  
Blood Cell ◽  
Essential Thrombocythemia ◽  
Myeloproliferative Neoplasms ◽  
Hematological Parameters ◽  
Jak2 V617f ◽  
Primary Myelofibrosis ◽  
Myeloproliferative Disorders ◽  
Jak2 V617f Mutation ◽  
V617f Mutation ◽  
The Difference

AbstractObjectiveDetection ofJAK2V617F in myeloproliferative neoplasms (MPNs) is very important in both diagnosis and disease progression. In our study, we investigated the frequency ofJAK2V617F mutation in patients with myeloproliferative disorders.MethodsWe retrospectively reviewed the records of 720 patients (174 females and 546 males) who were tested for JAK2 V617F mutation from January 2007 to December 2017.ResultsIn our patients were determined 22.6%JAK2V617F mutation. 33.3% in women, 19.2% in men have been positive forJAK2V617F mutation. In our studyJAK2V617F present in 48.6% of essential thrombocythemia, 80.5% of polycythemia rubra vera (PV), 47.5% of primary myelofibrosis, 10% of MPNs, unclassifiable, 0.8% of others. We also investigated the difference in hematological parameters [white blood cell, hemoglobin (Hb), hematocrit (HCT), red blood cell distribution widths (RDW) and platelets count (PLT)] betweenJAK2V617F positive andJAK2V617F negative patients.ConclusionsInvestigation of the JAK2 V617F mutation is very important in cases of MPNs. In our study JAK2 V617F mutation was higher in PV, essential thrombocythemia, and primary myelofibrosis patients. However, there were significant differences in Hb, HCT, RDW and PLT levels in mutation-positive patients.

scholarly journals The JAK2 V617F mutation in de novo acute myelogenous leukemias

Oncogene ◽  
2005 ◽  
Vol 25 (9) ◽  
pp. 1434-1436 ◽  
Author(s):  
J W Lee ◽  
Y G Kim ◽  
Y H Soung ◽  
K J Han, ◽  
S Y Kim ◽  
...  
Keyword(s):  
De Novo ◽  
Jak2 V617f ◽  
Jak2 V617f Mutation ◽  
Acute Myelogenous ◽  
V617f Mutation

Relation between JAK2 (V617F) mutation status, granulocyte activation, and constitutive mobilization of CD34+ cells into peripheral blood in myeloproliferative disorders

Blood ◽  
2006 ◽  
Vol 107 (9) ◽  
pp. 3676-3682 ◽  
Author(s):  
Francesco Passamonti ◽  
Elisa Rumi ◽  
Daniela Pietra ◽  
Matteo G. Della Porta ◽  
Emanuela Boveri ◽  
...  
Keyword(s):  
Polycythemia Vera ◽  
Gene Dosage ◽  
Jak2 V617f ◽  
Myeloproliferative Disorders ◽  
Jak2 V617f Mutation ◽  
Disease Category ◽  
Mutation Status ◽  
Cell Counts ◽  
Cd34 Cells ◽  
V617f Mutation

We studied the relationship between granulocyte JAK2 (V617F) mutation status, circulating CD34+ cells, and granulocyte activation in myeloproliferative disorders. Quantitative allele-specific polymerase chain reaction (PCR) showed significant differences between various disorders with respect to either the proportion of positive patients (53%-100%) or that of mutant alleles, which overall ranged from 1% to 100%. In polycythemia vera, JAK2 (V617F) was detected in 23 of 25 subjects at diagnosis and in 16 of 16 patients whose disease had evolved into myelofibrosis; median percentages of mutant alleles in these subgroups were significantly different (32% versus 95%, P < .001). Circulating CD34+ cell counts were variably elevated and associated with disease category and JAK2 (V617F) mutation status. Most patients had granulocyte activation patterns similar to those induced by administration of granulocyte colony-stimulating factor. A JAK2 (V617F) gene dosage effect on both CD34+ cell counts and granulocyte activation was clearly demonstrated in polycythemia vera, where abnormal patterns were mainly found in patients carrying more than 50% mutant alleles. These observations suggest that JAK2 (V617F) may constitutively activate granulocytes and by this means mobilize CD34+ cells. This exemplifies a novel paradigm in which a somatic gain-of-function mutation is initially responsible for clonal expansion of hematopoietic cells and later for their abnormal trafficking via an activated cell progeny.

Myeloid Blasts in Transformed JAK2-V617F Positive Myeloproliferative Disorders Are Frequently Negative for the JAK2-V617F Mutation.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 375-375 ◽  
Author(s):  
Alexandre Theocharides ◽  
Marjorie Boissinot ◽  
Richard Garand ◽  
François Girodon ◽  
Soon-Siong Teo ◽  
...  
Keyword(s):  
De Novo ◽  
Jak2 V617f ◽  
Myeloproliferative Disorders ◽  
Jak2 V617f Mutation ◽  
Jak2 Mutation ◽  
Allelic Ratio ◽  
Pcr Products ◽  
Blast Cells ◽  
V617f Mutation ◽  
De Novo Aml

Abstract Acute myeloid leukemia (AML) is a common complication of myeloproliferative disorders (MPDs). The role of the JAK2-V617F mutation in this process is unknown. We performed a retrospective analysis of DNA samples from MPD patients with secondary AML. We analysed DNA samples taken at the time of transformation to AML from 54 MPD patients (24 PV, 21 ET, 9 IMF). In addition, DNA samples taken at diagnosis of MPD were obtained in 21 of these patients. DNA was extracted from bone marrow or peripheral blood films, purified granulocytes or frozen cells. FACS sorting of blast cells, T cells and neutrophils was performed in some of the samples. The allelic ratio of JAK2-V617F was determined by allele-specific quantitative PCR (AS-PCR). We obtained AS-PCR data on 52/54 samples taken at the time of transformation (96%), whereas 2 samples did not yield PCR products: 24/52 samples were negative for JAK2-V617F (46%) and 28/52 were positive (54%). For 14/24 negative patients (58%) we had additional DNA samples taken at the time of MPD diagnosis and interestingly, 5 of these 14 patients (36%) were positive for JAK2-V617F at this earlier time point before AML transformation. This suggests that in these patients the JAK2-V617F positive clone was lost during the evolution to AML. Furthermore, comparison of the JAK2-V617F allelic ratios with the percentage of blast cells in patient samples positive at transformation revealed 8/28 cases where the JAK2-V617F allelic ratio was markedly lower than the percentage of blasts, e.g. 8%T-allele and 52% myeloid blast cells. In these patients a JAK2-V617F negative AML clone most likely co-exists with a JAK2-V617F positive MPD clone. To address the question whether the AML clone arose independently from the JAK2-V617F clone, we analyzed loss of heterozygosity on chromosome 9p (9pLOH) in one informative patient who displayed a high allelic ratio of mutant JAK2 at diagnosis (94%T). The CD15+ cells from this patient showed 9pLOH at diagnosis, as demonstrated with two independent microsatellite markers. In contrast, the FACS sorted blast cells at the time of transformation contained both parental alleles in the 9p region and were JAK2-V617F negative by AS-PCR. This excludes the possibility that the AML clone lost the JAK2V617F in the process of undergoing mitotic recombination at a stage heterozygous for JAK2-V617F. Analysis of additional patients is under way. In summary, we found in a cohort of 54 MPD patients, 13 patients initially positive for JAK2-V617F that transformed into JAK2-V617F negative AML. Although not confirmed in the one patient analyzed, we cannot exclude that other patients the JAK2-V617F positive MPD clone lost the JAK2 mutation during the process of transformation. Alternatively, the AML clone could have developed de novo from a JAK2-V617F negative progenitor or stem cell. The latter model has difficulties explaining the high incidence of de novo AML (8/54 patients), unless the JAK2-V617F negative progenitor already carried an as yet unknown mutation and was part of the MPD clone.

Sequential Analysis By Next Generation Sequencing of 18 Genes in Polycythemia Vera and Essential Thrombocythemia Reveals a Association Between Mutational Status and Clinical Outcome after 3-Year Follow-up

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2808-2808
Author(s):  
Damien Luque Paz ◽  
Aurelie Chauveau ◽  
Caroline Buors ◽  
Jean-Christophe Ianotto ◽  
Francoise Boyer ◽  
...  
Keyword(s):  
Polycythemia Vera ◽  
Essential Thrombocythemia ◽  
Jak2 V617f ◽  
Primary Myelofibrosis ◽  
Jak2 V617f Mutation ◽  
Poor Prognostic Factor ◽  
Disease Evolution ◽  
Allele Burden ◽  
V617f Mutation

Abstract Introduction Myeloproliferative neoplasms (MPN) are molecularly characterized by driver mutations of JAK2, MPL or CALR. Other somatic mutations may occur in epigenetic modifiers or oncogenes. Some of them have been shown to confer a poor prognosis in primary myelofibrosis, but their impact is less known in Polycythemia Vera (PV) and Essential Thrombocythemia (ET). In this study, we investigated the mutational profile using NGS technology in 50 JAK2 V617F positive cases of MPN (27 PV and 23 ET) collected at the time of diagnosis and after a 3 year follow-up (3y). Patients and Methods All patients were JAK2 V617F positive and already included in the prospective cohort JAKSUIVI. All exons of JAK2, MPL, LNK, CBL, NRAS, NF1, TET2, ASXL1, IDH1 and 2, DNMT3A, SUZ12, EZH2, SF3B1, SRSF2, TP53, IKZF1 and SETBP1 were covered by an AmpliseqTM custom design and sequenced on a PGM instrument (Life Technologies). CALR exon 9 mutations were screened using fragment analysis. Hotspots that mutated recurrently in MPN with no sequencing NGS coverage were screened by Sanger sequencing and HRM. A somatic validation was performed for some mutations using DNA derived from the nails. The increase of a mutation between diagnosis and follow-up has been defined as a relative increase of twenty percent of the allele burden. An aggravation of the disease at 3y was defined by the presence of at least one of the following criteria: leukocytosis &gt;12G/L or immature granulocytes &gt;2% or erythroblasts &gt;1%; anemia or thrombocytopenia not related to treatment toxicity; development or progressive splenomegaly; thrombocytosis on cytoreductive therapy; inadequate control of the patient's condition using the treatment (defined by at least one treatment change for reasons other than an adverse event). Results As expected, the JAK2 V617F mutation was found in all patients with the use of NGS. In addition, we found 27 other mutations in 10 genes out of the 18 genes studied by NGS (mean 0.54 mutations per patient). Overall, 29 of 50 patients had only the JAK2 V617F mutation and no other mutation in any of the genes analysed. No CALR mutation was detected. Nine mutations that were not previously described in myeloid malignancies were found. The genes involved in the epigenetic regulation were those most frequently mutated: TET2, ASXL1, IDH1, IDH2 and DNMT3A. In particular, TET2 mutations were the most frequent and occurred in 20% of cases. There was no difference in the number or in the presence of mutations between PV and ET. At 3y, 4 mutations appeared in 4 patients and 15 out of 50 patients (9 PV and 6 ET) were affected by an allele burden increase of at least one mutation. At 3y, 24/50 patients suffered an aggravation of the disease as defined by the primary outcome criterion (16 PV and 8 ET). The presence of a mutation (JAK2 V617Fomitted) at the time of the diagnosis was significantly associated with the aggravation of the disease (p=0.025). Retaining only mutations with an allele burden greater than 20%, the association with disease aggravation is more significant (p=0.011). Moreover, a mutation of ASXL1, IDH1/2 or SRSF2, which is a poor prognostic factor in primary myelofibrosis, was found in 8 patients, all having presented an aggravation of their disease (p=0.001). Only 4 patients had more than one somatic mutation other than JAK2 V617F and all of them also had an aggravation at 3y (p=0.046). In this cohort, appearance of a mutation at 3y was not associated with the course of the disease. Conversely, the increase of allele burden of at least one mutation was associated with an aggravation (p=0.019). Discussion and conclusion Despite the short follow-up and the limited number of patients, this study suggests that the presence of additional mutations at the time of the diagnosis in PV and TE is correlated to a poorer disease evolution. The increase of mutation allele burden, which reflects clonal evolution, also seems to be associated with the course of the disease. These results argue for a clinical interest in large mutation screening by NGS at the time of the diagnosis and during follow-up in ET and PV. Disclosures Ugo: Novartis: Membership on an entity's Board of Directors or advisory committees, Other: ASH travel.

Leukemic blasts in transformed JAK2-V617F–positive myeloproliferative disorders are frequently negative for the JAK2-V617F mutation.

Blood ◽  
2007 ◽  
Vol 110 (1) ◽  
pp. 375-379 ◽  
Author(s):  
Alexandre Theocharides ◽  
Marjorie Boissinot ◽  
François Girodon ◽  
Richard Garand ◽  
Soon-Siong Teo ◽  
...  
Keyword(s):  
Myeloid Leukemia ◽  
Jak2 V617f ◽  
Myeloproliferative Disorders ◽  
Microsatellite Analysis ◽  
Jak2 V617f Mutation ◽  
Leukemic Transformation ◽  
Clonal Origin ◽  
V617f Mutation ◽  
Acute Myeloid

To study the role of the JAK2-V617F mutation in leukemic transformation, we examined 27 patients with myeloproliferative disorders (MPDs) who transformed to acute myeloid leukemia (AML). At MPD diagnosis, JAK2-V617F was detectable in 17 of 27 patients. Surprisingly, only 5 of 17 patients developed JAK2-V617F–positive AML, whereas 9 of 17 patients transformed to JAK2-V617F–negative AML. Microsatellite analysis in a female patient showed that mitotic recombination was not responsible for the transition from JAK2-V617F–positive MPD to JAK2-V617F–negative AML, and clonality determined by the MPP1 polymorphism demonstrated that the granulocytes and leukemic blasts inactivated the same parental X chromosome. In a second patient positive for JAK2-V617F at transformation, but with JAK2-V617F–negative leukemic blasts, we found del(11q) in all cells examined, suggesting a common clonal origin of MPD and AML. We conclude that JAK2-V617F–positive MPD frequently yields JAK2-V617F–negative AML, and transformation of a common JAK2-V617F–negative ancestor represents a possible mechanism.

The Hematopoietic Stem Cell Compartment Is Different in Polycythemia Vera and Idiopathic Myelofibrosis.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 259-259 ◽  
Author(s):  
Chloe James ◽  
Frederic Mazurier ◽  
Ronan Chaligne ◽  
Sabrina Dupont ◽  
Francois Delhommeau ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
B Lymphocytes ◽  
Jak2 V617f ◽  
Jak2 V617f Mutation ◽  
Hematopoietic Stem ◽  
Cd34 Cells ◽  
V617f Mutation ◽  
Myeloid Progenitors

Abstract X-linked clonality studies showed that myeloproliferative disorders derive from an abnormal hematopoietic stem cell (HSC). This has been recently confirmed by studies showing that the JAK2 V617F mutation was present in multipotent cells from patients with Polycythemia Vera (PV), Essential Thrombocythemia (ET) and Primitive Myelofibrosis (PMF). How one unique mutation could give rise to three different diseases remains unexplained and we hypothesized that the HSC compartment may be different in PV and PMF. To investigate whether the V617F mutation occurs in HSCs in PV and PMF, and whether the HSC compartments are different in these 2 diseases, we performed simultaneously two types of experiments: Myeloid, B, and NK in vitro differentiation assays and Repopulation of immune-deficient NOD/SCID mice with human JAK2 V617F CD34+ cells followed by analysis of the frequency of JAK2 V617F clones. We first confirmed that the JAK2 V617F mutation is present in HSCs, enabling long-term (15 weeks) in vivo hematopoietic reconstitution, both in PV and PMF patients. Nevertheless, we found marked differences between PV and PMF samples. Indeed, the frequency of JAK2 V617F lympho-myeloid progenitors was much higher in MF (6 PMF and one post PV-MF) than in PV patients (n = 9) (87.2% +/− 31.3 vs 21% +/− 21.1 respectively). Similarly, most of the human myeloid progenitors present in mice transplanted with CD34+ cells from MF patients (n = 7) 15 weeks post-transplantation were JAK2 V617F. On the contrary, human myeloid progenitors were predominantly JAK2 WT after transplantation of PV CD34+ cells (9 patients). To determine if the mutation was present in HSC able to differentiate into B-lymphocytes in PV and MF, we sorted and genotyped the fraction of B-lymphocytes (CD45+CD19+) that differentiated in the bone marrow of mice. In 5 mice transplanted with PV CD34+ cells, the fraction of B-cells was always JAK2 WT whereas in 2 out of 3 mice transplanted with MF CD34+ cells, B-lymphocytes were JAK2 V617F. To determine if the mutation was present in HSC capable of very long-term reconstitution in PV and PMF, we looked for the presence of long-term culture-initiating cells (LTC-IC) among human CD34+ cells isolated from the bone marrow of NOD/SCID mice (2 PV, 3 MF) 15 weeks after transplantation. In 2 mice transplanted with PMF CD34+ cells, the majority of LTC-ICs (70/70 and 95/166) were JAK2 V617F. On the contrary, in 3 mice reconstituted with PV CD34+ cells, most of the LTC-ICs were JAK2 WT (23/23, 4/4 and 126/168) although we could find some LTC-ICs that were JAK2 V617F, demonstrating that in PV also, the JAK2 V617F mutation is present in Long Term-HSC. Taken together these results demonstrate that the JAK2 V617F mutation is present in a small subset of HSCs in PV patients, whereas in MF, the vast majority of HSCs is JAK2 V617F. This suggests that these two diseases are two stages of the same pathology and that in MF the JAK2 V617F HSCs have acquired a proliferative advantage on JAK2 WT HSCs and thus have invaded the hematopoietic system.

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