The JAK2V617 mutation induces constitutive activation and agonist hypersensitivity in basophils from patients with polycythemia vera

Background

The JAK2V617F mutation has been associated with constitutive and enhanced activation of neutrophils, while no information is available concerning other leukocyte subtypes.

Design and Methods

We evaluated correlations between JAK2V617F mutation and the count of circulating basophils, the number of activated CD63⁺ basophils, their response in vitro to agonists as well as the effects of a JAK2 inhibitor.

Results

We found that basophil count was increased in patients with JAK2V617F -positive myeloproliferative neoplasms, particularly in those with polycythemia vera, and was correlated with the V617F burden. The burden of V617F allele was similar in neutrophils and basophils from patients with polycythemia vera, while total JAK2 mRNA content was remarkably greater in the basophils; however, the content of JAK2 protein in basophils was not increased. The number of CD63⁺ basophils was higher in patients with polycythemia vera than in healthy subjects or patients with essential thrombocythemia or primary myelofibrosis and was correlated with the V617F burden. Ultrastructurally, basophils from patients with polycythemia vera contained an increased number of granules, most of which were empty suggesting cell degranulation in vivo. Ex vivo experiments revealed that basophils from patients with polycythemia vera were hypersensitive to the priming effect of interleukin-3 and to f-MLP-induced activation; pre-treatment with a JAK2 inhibitor reduced polycythemia vera basophil activation. Finally, we found that the number of circulating CD63⁺ basophils was significantly greater in patients suffering from aquagenic pruritus, who also showed a higher V617F allele burden.

Conclusions

These data indicate that the number of constitutively activated and hypersensitive circulating basophils is increased in polycythemia vera, underscoring a role of JAK2V617F in these cells’ abnormal function and, putatively, in the pathogenesis of pruritus.     

Sex differences in the JAK2V617F allele burden in chronic myeloproliferative disorders

Background

The JAK2^V617F allele burden is a variable measure, determined by the frequency of mitotic recombination events and the expansion of JAK2^V617F clones. Since variability in the JAK2^V617F allele burden is partly responsible for the distinct phenotypes seen in the myeloproliferative disorders, the objective of this study was to identify modifiers of the allele burden.

Design and Methods

Blood samples were obtained between May 2005 and January 2009 from 272 patients with essential thrombocytosis, polycythemia vera, and myelofibrosis. The JAK2^V617F allele burden was measured by an allele-specific quantitative polymerase chain reaction using DNA from purified neutrophils. Repeated measures, on average 2 years apart, were available for 104 patients.

Results

Sex, age at diagnosis, and disease duration all independently influenced the JAK2^V617F allele burden. When considering all patients with myeloproliferative disorders, women had significantly lower allele burdens than men (P=0.04). In those patients with repeated measures, the increase in allele burden per year between the first and second evaluations was significantly less in females than in males. Among those who experienced disease evolution, females were 4.5 times more likely to have evolution from essential thrombocytosis to polycythemia vera, but 0.23 times as likely to have evolution from essential thrombocytosis to myelofibrosis.

Conclusions

Sex is an independent factor accounting for variability in the JAK2^V617F allele burden. We speculate that lower allele burdens in females reflect a lower frequency of mitotic recombination events in females than in males, and should be considered when evaluating the relationship of allele burden to disease phenotype and also in evaluating responses to JAK2^V617F-inhibitors. Because sex may influence genotype and/or clonal expansion, underpinning the variability in JAK2^V617F allele burden, it will be important to explore factors that determine susceptibility to mitotic recombination events.     

Comparison of JAK2V617F mutation assessment employing different molecular diagnostic techniques

Background

The JAK2^V617F mutation is present in the majority of patients with polycythaemia vera and in approximately half of patients with essential thrombocythaemia and primary myelofibrosis. In this study we compare the results of JAK2^V617F mutation detection using three different molecular techniques in the same group of patients affected by essential thrombocythaemia.

Patients and methods

The JAK2 mutation was investigated with a qualitative method in 115 consecutive outpatients with a diagnosis of essential thrombocythaemia made according to WHO 2001 criteria. In 48/115 (41.7%) the allele burden was also evaluated with two different qualitative methods, of which one was a method developed in-house and the other was a commercially available method.

Results

The JAK2^V617F mutation was detected by the qualitative method in 81/115 (69.6%) of the patients. Among the 48/115 patients in whom all three methods were applied, the qualitative method detected the mutation in 38 (79%). According to the quantitative method developed in-house, the mutation was present in 35/48 (73%) of the patients: of these, 2/35 (5.7%) patients were homozygous for the JAK2^V617F mutation. The commercial quantitative method showed the mutation in 37/48 (77%) patients: of these, 9/37 (18%) patients were homozygous. Three of the 13 patients in whom no mutation was detected by the in-house method were positive for the JAK2^V617F according to the commercial method. In one patient the search for the JAK2^V617F mutation was positive with the in-house method but negative with the commercial kit.

Conclusion

Detection of the JAK2^V617F mutation may depend on the molecular technique used. Considering that detection of this mutation will not only have a diagnostic value, but also a role in treatment given the development of JAK2^V617F pathway inhibiting drugs, indications on a reference molecular diagnostic technique for JAK2^V617F assessment and quantification of its allele burden from a panel of experts are warranted.     

Disruption of the ASXL1 gene is frequent in primary, post-essential thrombocytosis and post-polycythemia vera myelofibrosis, but not essential thrombocytosis or polycythemia vera: analysis of molecular genetics and clinical phenotypes

Background

The myeloproliferative neoplasms, essential thrombocytosis, polycythemia vera and primary myelofibrosis, share the same acquired genetic lesion, but the concept of JAK2 V617F serving as the sole lesion responsible for these neoplasms is under question, and there has been interest in identifying additional mutations that may contribute to disease pathogenesis. Because ASXL1 lesions have been increasingly identified in myeloid neoplasms, we examined the relationships of ASXL1 mutation or deletion to both clinical phenotype and associated molecular features in 166 patients with myeloproliferative neoplasms.

Design and Methods

Exon 12 of ASXL1 was amplified from neutrophil genomic DNA and bidirectionally sequenced in 77 patients with myelofibrosis (including patients with primary and post-essential thrombocytosis or post-polycythemia myelofibrosis), 42 patients with polycythemia vera, 41 with essential thrombocytosis and 6 with post-myelofibrosis acute myeloid leukemia. Pyrosequencing assays were designed to determine the allele percentages of JAK2 V617F (G5073770T), ASXL1 2475dupA, and ASXL1 2846_2847del in neutrophil genomic DNA samples. Clinical and laboratory characteristics of patients with wild-type and ASXL1 mutations were then compared.

Results

We identified nonsense mutations or hemizygous deletion of ASXL1 in 36% of the patients with myelofibrosis, but very rarely among those with polycythemia vera or essential thrombocytosis. Among the patients with myelofibrosis, those with ASXL1 lesions were not distinguished from their wild-type counterparts with regard to JAK2 V617F status, exposure to chemotherapy or evolution to leukemia. Myelofibrosis patients with ASXL1 lesions were more likely to have received anemia-directed therapy compared to those without lesions [15/26 (58%) versus 11/39 (23%); P=0.02]. Using serial banked samples and quantitative ASXL1 mutant allele burden assays, we observed the acquisition and accumulation of ASXL1 mutations over time in two patients with post-essential thrombocytosis myelofibrosis.

Conclusions

ASXL1 haploinsufficiency is associated with a myelofibrosis phenotype in the context of other known and unknown lesions, and disruption of ASXL1 function may contribute to the disease pathogenesis of myelofibrosis.     

CBL mutations in myeloproliferative neoplasms are also found in the gene's proline-rich domain and in patients with the V617FJAK2

Background

Despite the discovery of the p.V617F in JAK2, the molecular pathogenesis of some chronic myeloproliferative neoplasms remains unclear. Although very rare, different studies have identified CBL (Cas-Br-Murine ecotropic retroviral transforming sequence) mutations in V617FJAK2-negative patients, mainly located in the RING finger domain. In order to determine the frequency of CBL mutations in these diseases, we studied different regions of all CBL family genes (CBL, CBLB and CBLC) in a selected group of patients with myeloproliferative neoplasms. We also included V617FJAK2-positive patients to check whether mutations in CBL and JAK2 are mutually exclusive events.

Design and Methods

Using denaturing high performance liquid chromatography, we screened for mutations in CBL, CBLB and CBLC in a group of 172 V617FJAK2-negative and 232 V617FJAK2-positive patients with myeloproliferative neoplasms not selected for loss of heterozygosity. The effect on cell proliferation of the mutations detected was analyzed on a 32D(FLT3) cell model.

Results

An initial screening of all coding exons of CBL, CBLB and CBLC in 44 V617FJAK2-negative samples revealed two new CBL mutations (p.C416W in the RING finger domain and p.A678V in the proline-rich domain). Analyses performed on 128 additional V617FJAK2-negative and 232 V617FJAK2-positive samples detected three CBL changes (p.T402HfsX29, p.P417R and p.S675C in two cases) in four V617FJAK2-positive patients. None of these mutations was found in 200 control samples. Cell proliferation assays showed that all of the mutations promoted hypersensitivity to interleukin-3 in 32D(FLT3) cells.

Conclusions

Although mutations described to date have been found in the RING finger domain and in the linker region of CBL, we found a similar frequency of mutations in the proline-rich domain. In addition, we found CBL mutations in both V617FJAK2-positive (4/232; 1.7%) and negative (2/172; 1.2%) patients and all of them promoted hypersensitivity to interleukin-3.     

Is the absence of JAK2V617F mutation a risk factor for bleeding in essential thrombocythemia? An analysis of 106 patients

Background

JAK2^V617F mutation has been recognized as a possible thrombotic risk factor in essential thrombocythaemia (ET). It’s role is probably due to an increased myeloid proliferation and white blood cells (WBC) activation. Only few data are available about the effect of JAK2^V617F on hemorrhagic risk. The aim of our study was to evaluate the influence of the mutational status on hemorrhagic complication.

Methods

We retrospectively analysed laboratory and clinical findings of 106 consecutive patients with ET to evaluate possible relationships between thrombosis, abnormal bleeding, peripheral blood count, overexpression of PRV1 and JAK2^V617F mutational status.

Results

On univariate analysis we found: an association between JAK2^V617F mutation and thrombotic events before or at diagnosis (p<0.003, OR=4.44, 95% CI=1.74–12.4); no statistical correlation between the median value of JAK2^V617F burden and an increased risk of thrombosis (p=0.4, 95% CI= −22.8–10.4); significant relationships between mutated status and higher haematocrit, high WBC count and low platelet count; and a strong correlation between JAK2^V617F and PRV1 overexpression (p<0.0001). Moreover, the presence of the JAK2^V617F mutation and a WBC count greater than 8.4 × 10⁹/L were found to be independent factors related to thrombotic complications in multivariable analysis (p<0.006, OR=3.85, 95% CI=1.3–11.9; and p<0.002, OR=2.8, 95% CI=1.08–7.03, respectively). The prognostic impact of JAK2 mutation status and WBC count on thrombosis was evaluated in the whole cohort. Only new cases occurring in patients without previous thrombotic events were recorded for the analysis. The multivariable analysis showed a statistical correlation between the presence of the mutation and a WBC count greater than 8.12 × 10⁶/L and an increased risk of thrombosis if no cytoreductive treatment was started at diagnosis (JAK2^V617F p=0.02; WBC p=0.02; OR=4.97; 95% CI=1.04–23.8). Finally, wild-type JAK2 was associated with a higher haemorrhagic risk (p=0.02) in univariate analysis but only a platelet count greater than 1,022 × 10⁹/L was associated with an increased risk of bleeding in the multivariable analysis.

Conclusion

Our data confirm the role of both JAK2^V617F as factor associated with an increased risk of thrombosis at the diagnosis and during follow-up in no treated patients. Moreover a WBC count over 8.4×10⁹/L¹ was also strictly associated to an increased risk of thrombosis. Regarding bleedings, our statistical analysis allows to exclude the mutation protective role on haemorrhage.     

Frequent reduction or absence of detection of the JAK2-mutated clone in JAK2V617F-positive patients within the first years of hydroxyurea therapy

We analyzed the effect of hydroxyurea on the JAK2V617F allelic ratio (%JAK2V617F), measured in purified blood granulocytes, of patients with polycythemia vera and essential thrombocythemia. Thirty-six patients were examined sequentially prior to and after start of hydroxy-urea therapy (8 polycythemia vera, 17 essential thrombocythemia), or while remaining untreated (2 polycythemia vera, 9 essential thrombocythemia). Hydroxyurea therapy (median duration: 15 months) reduced the %JAK2V617F by >30% in 13/25 patients (4 polycythemia vera, 9 essential thrombocythemia). For 3 patients, JAK2V617F remained undetectable for 3-27 months. In addition, a single time point study of two large cohorts of patients, examined either at the time of diagnosis (99 polycythemia vera, 178 essential thrombocythemia) or while receiving hydroxyurea (36 polycythemia vera, 98 essential thrombocythemia; median length of therapy: 32 months), confirmed reduction of %JAK2V617F in the hydroxyurea-treated group (24% vs. 33% JAK2V617F at diagnosis, p<0.01). Prospective studies are needed to determine the prognostic value of reduced JAK2V617F allele burden under cytoreductive therapy.     

Concordance of assays designed for the quantification of JAK2V617F: a multicenter study

Background

Many different techniques have been designed for the quantification of JAK2V617F allelic burden, sometimes producing discrepant results.

Design and Methods

JAK2V617F quantification techniques were compared among 16 centers using 11 assays based on quantitative polymerase chain reaction (with mutation-specific primers or probes, or fluorescent resonance energy transfer/melting curve analysis), allele-specific polymerase chain reaction, conventional sequencing or pyrosequencing.

Results

A first series of blinded samples (granulocyte DNA, n=29) was analyzed. Seven assays (12 centers) reported values inside the mean±2SD; the mean coefficient of variation was 31%. Sequencing techniques lacked sensitivity, and strong discrepancies were observed with four techniques, which could be attributed to inadequate standards or to different modes of expression of results. Indeed, quantification of JAK2V617F in relation to another control gene produced higher than expected values, suggesting the possibility of more than two JAK2 copies/cell. After calibration of assays with common 1% to 100% JAK2V617F standards (dilutions of UKE-1 cells in normal leukocytes), 14 centers tested ten new samples. JAK2V617F allelic burdens greater or equal than 1% were then reliably quantified by five techniques – one allele specific-polymerase chain reaction and four TaqMan allele-specific quantitative polymerase chain reaction assays, including one previously giving results outside the mean±2SD – with a lower mean coefficient of variation (21%). Of these, only the two TaqMan allele-specific quantitative polymerase chain reaction assays with primer-based specificity could detect 0.2% JAK2V617F.

Conclusions

Techniques expressing the allelic burden as JAK2V617F/total JAK2 and using a common set of standards produced similar quantification results but with variable sensitivity. Calibration to a reference standard improved reproducibility.     

Minimal molecular response in polycythemia vera patients treated with imatinib or interferon alpha

Imatinib and recombinant interferon alpha (rIFNalpha) can induce remission in polycythemia vera (PV) patients, but gauging the depth of responses has not been possible due to lack of a specific disease marker. We found that patients undergoing imatinib (n = 14) or rIFNalpha (n = 7) therapy remained strongly positive for V617F JAK2, although there was a significant reduction in the median percentage of mutant alleles that correlated with hematologic response (P = .001). Furthermore, individuals who achieved complete hematologic remission had lower levels of V617F than those who did not (P = .001). Of 9 imatinib-treated cases for whom pretreatment samples were available, 7 with no or partial hematologic responses showed a marginal increase (median, 1.2-fold; range, 1.0-1.5) in the percentage of V617F alleles on treatment, whereas the 2 patients who achieved complete hematologic remission showed a 2- to 3-fold reduction. Our data indicate that, although PV patients may benefit from imatinib or rIFNalpha, molecular responses are relatively modest.     

Molecular analyses of 15,542 patients with suspected BCR-ABL1-negative myeloproliferative disorders allow to develop a stepwise diagnostic workflow

We investigated 15,542 patients with suspected BCR-ABL1- negative myeloproliferative or myelodysplastic/myeloproliferative neoplasm (including 359 chronic myelomonocytic leukemia) by a molecular marker set. JAK2V617F was detected in the suspected categories as follows: polycythemia vera 88.3%, primary myelofibrosis 53.8%, essential thrombocythemia 50.2%, and not further classifiable myeloproliferative neoplasms 38.0%. JAK2 exon 12 mutations were detected in 40.0% JAK2V617F-negative suspected polycythemia vera, MPLW515 mutations in 13.2%JAK2V617F-negative primary myelofibrosis and 7.1% JAK2V617F-negative essential thrombocythemia. TET2 mutations were distributed across all entities but were most frequent in suspected chronic myelomonocytic leukemia (77.8%). CBL mutations were identified in suspected chronic myelomonocytic leukemia (13.9%), primary myelofibrosis (8.0%), and not further classifiable myeloproliferative neoplasm (7.0%). This leads to a stepwise workflow for suspected myeloproliferative neoplasms starting with JAK2V617F and investigating JAK2V617F-negative patients for JAK2 exon 12 or MPL mutations, respectively. In cases in which a myeloproliferative neoplasm cannot be established, analysis for TET2, CBL and EZH2 mutations may be indicated.Key words: myeloproliferative neoplasms, chronic myelomonocytic leukemia, molecular analyses, mutation screening, diagnostic workflow     

Differential expression of JAK2 and Src kinase genes in response to hydroxyurea treatment in polycythemia vera and essential thrombocythemia

This study investigates the differential gene expression profile of JAK2^V617F-positive myeloproliferative neoplasm (MPN) patients, with and without response to hydroxyurea (HU) treatment. Twenty-one polycythemia vera, 28 essential thrombocythemia, eight secondary erythrocytosis, and 30 controls were studied. Thirty-four genes were overexpressed in patients who did not respond to HU. Of these, some participate in proliferative pathways: MAPK, AKT, Src kinase (SFK), and JAK2 pathway. JAK2 allele burden was similar between groups of responders and nonresponder. A molecular fingerprint distinguishes JAK2^V617F-positive MPN patients without response to HU treatment, with overexpression of JAK2, MAPK14, PIK3CA, and SFK genes.     

Determination of accuracy of polycythemia vera diagnoses and use of the JAK2V617F test in the diagnostic scheme

In 2005, three independent research groups described the presence of a specific mutation in the JAK2 gene, JAK2V617F, in patients with a Philadelphia chromosome-negative myeloproliferative neoplasm (MPN). The percentage of patients with the mutation varied according to specific disease with >98 % of polycythemia vera (PV) patients having the mutation. In 2008, the World Health Organization issued new diagnostic criteria for PV including use of the JAK2V617F test as a major diagnostic criterion. The goal of the present study is to determine the accuracy of diagnosing PV in a community practice and reporting of PV to cancer registries, as well as assessing the integration of molecular testing into diagnostic paradigms. Using Geisinger Medical Center’s electronic medical records (EMR), patients with a PV diagnosis being seen by a hematologist/oncologist during 2004–2009 were identified. Records were reviewed by a single hematologist/oncologist to determine accuracy of the treating physician’s diagnosis and use of the molecular test for the JAK2V617F mutation. There was a diagnosis of PV from the treating physicians in 121 of the 204 evaluable patients (59 %) and another MPN in 21 (10 %). However, we confirmed a PV diagnosis in only 90 patients (44 %). Of the 90 confirmed PV patients, 64 were JAK2V617F-mutation positive while 24 were not tested. While JAK2V617F testing has made a major impact in facilitating the successful delineation of the type of polycythemia (PV versus secondary polycythemia) in patients evaluated in a large, community-based Hematology/Oncology practice, physician usage of other critical tests is inconsistent leading to errors in diagnosis. JAK2V617F mutation testing in combination with other diagnostic criteria may help reduce diagnostic errors.     

A prospective multicenter observational study of decitabine treatment in Korean patients with myelodysplastic syndrome

Background

Decitabine was evaluated for its efficacy and safety in Korean patients with myelodysplastic syndrome with IPSS score of 0.5 or over.

Design and Methods

Decitabine 20 mg/m²/day was given intravenously over one hour for five consecutive days every four weeks. The primary end point was overall response rate.

Results

A total of 101 patients were analyzed. The International Prognostic Scoring System risk category was Intermediate-2/High in 47.5%. A median of 5 courses (range 1–18) were delivered. The overall response rate was 55.4% (13 complete responses, one partial response, 23 marrow complete responses, and 19 hematologic improvements). Forty-eight patients (47.5%) showed some hematologic improvement. With a median follow-up duration of 478 days (range 69–595), median overall survival was 17.7 months. Patients who showed hematologic improvement had significantly longer overall survival than those who did not (19.2 vs. 15.9 months, P=0.006 by landmark analysis at six months). The difference in overall survival was evident in the Intermediate-2/High risk group but not in the Intermediate-1 risk group. The progression-free survival and acute myeloid leukemia-free survival were 61.9% and 77.9% at one year, respectively. Among 489 assessable treatment courses, there were 97 fever episodes requiring intravenous antimicrobials.

Conclusions

Decitabine treatment was feasible and effective in Korean patients with myelodysplastic syndrome, and the overall survival was significantly longer in patients showing hematologic improvement.     

Early intervention during imatinib therapy in patients with newly diagnosed chronic-phase chronic myeloid leukemia: a study of the Spanish PETHEMA group

Background

Despite the favorable results of imatinib front line in chronic-phase chronic myeloid leukemia there is room for improvement.

Design and Methods

Early intervention during imatinib therapy was undertaken in 210 adults with chronic-phase chronic myeloid leukemia less than three months from diagnosis (Sokal high risk: 16%). Patients received imatinib 400 mg/day. At three months, dose was increased if complete hematologic response was not achieved. At six months, patients in complete cytogenetic response were kept on 400 mg and the remainder randomized to higher imatinib dose or 400 mg plus interferon-alfa. At 18 months, randomized patients were switched to a 2^nd generation tyrosine kinase inhibitor if not in complete cytogenetic response and imatinib dose increased in non-randomized patients not in major molecular response.

Results

Seventy-two percent of patients started imatinib within one month from diagnosis. Median follow-up is 50.5 (range: 1.2–78) months. At three months 4 patients did not have complete hematologic response; at six months 73.8% were in complete cytogenetic response; among the remainder, 9 could not be randomized (toxicity or consent withdrawal), 17 were assigned to high imatinib dose, and 15 to 400 mg + interferon-alpha. The low number of randomized patients precluded comparison between the two arms. Cumulative response at three years was: complete hematologic response 98.6%, complete cytogenetic response 90% and major molecular response 82%. On an intention-to-treat basis, complete cytogenetic response was 78.8% at 18 months. At five years, survival was 97.5%, survival free from accelerated/blastic phase 94.3%, failure free survival 82.5%, and event free survival (including permanent imatinib discontinuation) 71.5%.

Conclusions

These results indicate the benefit of early intervention during imatinib therapy (ClinicalTrials.gov Identifier: {"type":"clinical-trial","attrs":{"text":"NCT00390897","term_id":"NCT00390897"}}NCT00390897).     

High-dose imatinib improves cytogenetic and molecular remissions in patients with pretreated Philadelphia-positive, BCR-ABL-positive chronic phase chronic myeloid leukemia: first results from the randomized CELSG phase III CML 11 ��ISTAHIT�� study

Background

Imatinib 400 mg/day is the standard treatment for patients with chronic phase chronic myeloid leukemia. Recent reports suggested higher and more rapid cytogenetic and molecular responses with higher doses of imatinib.

Design and Methods

In this prospective international, multicenter phase III study, 227 patients with pre-treated Philadelphia chromosome-positive, BCR-ABL-positive chronic myeloid leukemia were randomized to a standard-dose imatinib arm (400 mg/day) or a high-dose imatinib arm (800 mg/day for 6 months followed by 400 mg/day as maintenance therapy). In this planned interim analysis hematologic, cytogenetic and molecular responses as well as toxicity were evaluated.

Results

Compared to the standard-dose, high-dose imatinib led to higher rates of major and complete cytogenetic responses at both 3 months (major: 21% versus 37%, P=0.01; complete: 6% versus 25%, P<0.001) and 6 months (major: 34% versus 54%, P=0.009; complete: 20% versus 44%, P<0.001). This was paralleled by a significantly higher major molecular response rate at 6 months in the high-dose imatinib arm (11.8% versus 30.4%; P=0.003). At 12 months, the rates of major cytogenetic response (the primary end-point) were comparable between the two arms (57% versus 59%). In contrast to non-hematologic toxicities, grade 3/4 hematologic toxicities were more common in the high-dose arm. Cumulative complete cytogenetic response rates were higher in patients without dose reduction in the high-dose arm (61%) than in the patients with no dose reduction in the standard-dose arm (36%) (P=0.014).

Conclusions

This is the first randomized phase III trial in patients with pre-treated chronic phase chronic myeloid leukemia demonstrating improvements in major cytogenetic response, complete cytogentic response and major molecular response rates with high-dose imatinib therapy (ClinicalTrials.gov Identifier: {"type":"clinical-trial","attrs":{"text":"NCT00327262","term_id":"NCT00327262"}}NCT00327262).     

Pulmonary artery pressure and iron deficiency in patients with upregulation of hypoxia sensing due to homozygous VHL(R200W) mutation (Chuvash polycythemia)

Background

Patients with Chuvash polycythemia, (homozygosity for the R200W mutation in the von Hippel Lindau gene (VHL)), have elevated levels of hypoxia inducible factors HIF-1 and HIF-2, often become iron-deficient secondary to phlebotomy, and have elevated estimated pulmonary artery pressure by echocardiography. The objectives of this study were to provide a comprehensive echocardiographic assessment of cardiovascular physiology and to identify clinical, hematologic and cardiovascular risk factors for elevation of tricuspid regurgitation velocity in children and adults with Chuvash polycythemia.

Design and Methods

This cross-sectional observational study of 120 adult and pediatric VHL^R200W homozygotes and 31 controls at outpatient facilities in Chuvashia, Russian Federation included echocardiography assessment of pulmonary artery pressure (tricuspid regurgitation velocity), cardiac volume, and systolic and diastolic function, as well as hematologic and clinical parameters. We determined the prevalence and risk factors for elevation of tricuspid regurgitation velocity in this population and its relationship to phlebotomy.

Results

The age-adjusted mean ± SE tricuspid regurgitation velocity was higher in VHL^R200W homozygotes than controls with normal VHL alleles (2.5±0.03 vs. 2.3±0.05 m/sec, P=0.005). The age-adjusted left ventricular diastolic diameter (4.8±0.05 vs. 4.5±0.09 cm, P=0.005) and left atrial diameter (3.4±0.04 vs. 3.2±0.08 cm, P=0.011) were also greater in the VHL^R200W homozygotes, consistent with increased blood volume, but the elevation in tricuspid regurgitation velocity persisted after adjustment for these variables. Among VHL^R200W homozygotes, phlebotomy therapy was associated with lower serum ferritin concentration, and low ferritin independently predicted higher tricuspid regurgitation velocity (standardized beta=0.29; P=0.009).

Conclusions

Children and adults with Chuvash polycythemia have higher estimated right ventricular systolic pressure, even after adjustment for echocardiography estimates of blood volume. Lower ferritin concentration, which is associated with phlebotomy, independently predicts higher tricuspid regurgitation velocity (www.clinicaltrials.gov identifier NCT00495638).     

Oncogenic JAK1 and JAK2-activating mutations resistant to ATP-competitive inhibitors

Background

Activating mutations in JAK1 and JAK2 have been described in patients with various hematologic malignancies including acute lymphoblastic leukemia and myeloproliferative neoplasms, leading to clinical trials with JAK inhibitors. While there has been a tremendous effort towards the development of specific JAK inhibitors, mutations conferring resistance to such drugs have not yet been observed.

Design and Methods

Taking advantage of a model of spontaneous cellular transformation, we sequenced JAK1 in selected tumorigenic BaF3 clones and identified 25 de novo JAK1 activating mutations, including 5 mutations already described in human leukemias. We further used this library of JAK1 mutation-positive cell lines to assess their sensitivity to ATP-competitive inhibitors.

Results

While most JAK1 mutants were sensitive to ATP-competitive JAK inhibitors, mutations targeting Phe958 and Pro960 in the hinge region of the kinase domain rendered JAK1 constitutively active but also resistant to all tested JAK inhibitors. Furthermore, mutation of the homologous Tyr931 in JAK2 wild-type or JAK2 V617F mutant found in patients with myeloproliferative neoplasms also conferred resistance to JAK inhibitors, such as INCB018424, which is currently in clinical use.

Conclusions

Our data indicate that some activating mutations not only promote autonomous cell proliferation but also confer resistance to ATP-competitive inhibitors. In vivo, such a mutation can potentially occur as primary JAK-activating mutations but also as secondary mutations combining oncogenicity with drug resistance.     

Histological regression of amyloid in AL amyloidosis is exclusively seen after normalization of serum free light chain

Background

Histological regression of amyloid has not been studied systematically but is assessed by clinical parameters. We analyzed the change of amyloid deposition in fat tissue in patients with AL amyloidosis following chemotherapy and studied the relation with type of hematologic response.

Design and Methods

Between January 1994 and July 2007 all consecutive patients with AL amyloidosis were evaluated in whom fat tissue aspirate was obtained before and following chemotherapy. Patients were divided into three groups depending on response of serum free light chain: complete, partial or non-responders. Fat tissue was assessed using a validated semi-quantitative test (grading 0–4). A change of 2 grades of amyloid deposition in fat tissue was considered significant and used as event to construct Kaplan-Meier curves of the patients who were able to reflect such a change.

Results

One hundred and twenty consecutive patients were studied. Fifty-one patients fulfilled inclusion criteria. Thirty patients had a complete response of the amyloidogenic free light chain a median 0.5 year (range 0.3–2.9 years) following chemotherapy. Reduction of 2 grades of amyloid deposition in fat tissue was seen in 50% of these patients after 2.4 years and in 80% after 3.2 years. In contrast to complete responders, none of the patients with partial (n=9) and non-response (n=12) showed reduction of 2 grades (p=0.02) with median follow-up of fat tissue analysis of 1.3 and 0.8 years, respectively.

Conclusions

This study in a selected group of patients with AL amyloidosis shows significant histological regression of amyloid deposition in fat tissue exclusively after normalization of serum free light chain.     

Initial management of noncirrhotic splanchnic vein thrombosis: When is anticoagulation enough?

BACKGROUND:

The optimal initial treatment of splanchnic vein thrombosis is uncertain. Anticoagulant therapy has been shown to be associated with vessel recanalization and decreased recurrence. Furthermore, information regarding potential predictors of chronic complications is not well understood.

METHODS:

A retrospective cohort study involving consecutive patients diagnosed with first-episode noncirrhotic splanchnic vein thrombosis referred to the thrombosis clinic of the authors’ institution between 2008 and 2011 was conducted. Demographic and clinical information was collected. The response to initial anticoagulant therapy was evaluated by determining radiographic recanalization of vessels and clinical resolution (defined as the absence of ongoing splanchnic vein thrombosis symptoms or complications requiring treatment beyond anticoagulant therapy).

RESULTS:

Twenty-two patients were included. Anticoagulant therapy alone resulted in vessel recanalization in 41% of patients and 68% achieved clinical resolution. Two patients experienced bleeding events. Factors associated with a lack of clinical resolution included signs of portal hypertension/liver failure on presentation, complete vessel occlusion at diagnosis, presence of a myeloproliferative disorder or JAK2^V617F tyrosine kinase mutation and the absence of a local/transient predisposing factor.

CONCLUSIONS:

Anticoagulant therapy appeared to be an effective initial treatment in patients with splanchnic vein thrombosis. Clinical factors may help to identify patients who are at risk for developing complications thus requiring closer monitoring. These findings were limited by the small sample size and need to be explored in larger prospective studies.     

The use and efficacy of empirical versus pre-emptive therapy in the management of fungal infections: the HEMA e-Chart Project

Background

Neutropenic patients with persistent fever despite antibiotic therapy are managed with empirical or pre-emptive antifungal therapy. The aim of the present study was to evaluate the current clinical use and efficacy of these two approaches in patients with high risk hematologic conditions.

Design and Methods

An electronic medical record system, the “Hema e-Chart”, was designed and implemented to collect information prospectively on infectious complications, particularly on invasive fungal diseases, in patients with hematologic malignancies treated with chemotherapy and/or autologous or allogenic hemopoietic stem cell transplantation. The patients were enrolled from Hematology units distributed widely across Italy.

Results

Three hundred and ninety-seven adults with hematologic malignancies treated with chemotherapy with persistent fever and suspected invasive fungal disease were evaluable for the study (190 treated had been treated with empirical antifungal therapy and 207 with preemptive antifungal therapy). There was a significantly lower incidence of proven/probable invasive fungal diseases in patients treated with empirical antifungal therapy (n=14, 7.4%) than in patients treated with pre-emptive therapy (n=49, 23.7%) (P<0.001). The rate of deaths attributable to invasive fungal diseases was significantly lower in subjects treated with empirical antifungal therapy (1 case; 7.1%) than in subjects treated with pre-emptive therapy (11 cases; 22.5%) (P=0.002).

Conclusions

These data indicate that empirical antifungal treatment decreased the incidence of invasive fungal disease and of attributable mortality with respect to a pre-emptive antifungal approach in neutropenic febrile patients with hematologic malignancies. (ClinicalTrials.gov Identifier: {"type":"clinical-trial","attrs":{"text":"NCT01069887","term_id":"NCT01069887"}}NCT01069887)