Prediction of thrombotic and hemorrhagic events during polycythemia vera or essential thrombocythemia based on leukocyte burden

Polycythemia Vera Presenting As Acute Non-hemorrhagic Infarction and Chronic Bleed: Deception Between the Lines

Patients with polycythemia vera (PV) develop various complications due to hyper-viscous blood, causing events such as ischemic stroke. There are other associated complications due to the dysfunction of platelet activity, causing hemorrhages. In our unusual case, we present a patient who came to the OPD complaining of slurring speech. An MRI was done and was suggestive of acute lacunar infarcts with changes in chronic bleed. CBC and hematocrit were consistent for PV, with the genetic marker JAK2 being positive.

Risk of thrombosis, hemorrhage and leukemic transformation in patients with myeloproliferative neoplasms: A nationwide longitudinal cohort study

INTRODUCTION

There are few large-scale, population-based studies detailing the risks of thrombosis, hemorrhage, leukemic transformation in patients with myeloproliferative neoplasms (MPNs), including essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF).

METHODS

We performed a nationwide longitudinal cohort study using the Korean National Health Insurance System (NHIS) database. MPN patients (n = 11,991) and their 1:4 age- and sex-matched controls (n = 47,964) were enrolled. The risk of thrombosis, hemorrhage, leukemic transformation was estimated using a Cox proportional hazards regression, and stratified analyses were performed for related factors.

RESULTS

During a median of 7.8 years of follow-up, 30.1 % of MPN patients (3614/11,991) and 19.0 % of the matched controls (9141/47,964) developed arterial thrombosis, 11.6 % of MPN patients (1397/11,991) and 6.4 % of the matched controls (3099/47,964) developed venous thrombosis and 18.7 % of MPN patients (2251/11,991) and 12.1 % of the matched controls (5836/47,964) developed hemorrhage. 4.9 % of MPN patients (597/11,991) and 0.1 % of matched controls (50/47,964) developed leukemia. The overall risk of developing thrombosis, hemorrhage, leukemic transformation was higher in MPN patients (adjusted hazard ratio [aHR] 1.695, 95 % confidence interval [CI]: 1.629-1.765 for arterial thrombosis, aHR 1.963, 95 % CI: 1.838-2.096 for venous thrombosis, and aHR 1.714, 95 % CI: 1.630-1.802 for hemorrhage) than in the controls. Patients with MPNs had a 10-year cumulative incidence of leukemic transformation of 6.2 %.

CONCLUSION

The patients with MPNs have a higher risk of thrombosis, hemorrhage, and leukemic transformation than matched controls. Strategies are warranted to reduce the risk of thrombosis, hemorrhage, and leukemic transformation in MPN patients.

JAK2V617F variant allele frequency, non-driver mutations, single-nucleotide variants and polycythemia vera outcome

INTRODUCTION

Despite comparatively favourable prognosis in polycythemia vera (PV) patients (pts), the overall survival is shorter compared to the age-matched general population. The aim of the study was to evaluate the impact of chosen laboratory and genetic factors on the individual disease outcome, i.e. risk of thrombosis, myelofibrosis/blastic transformation and death.

MATERIALS AND METHODS

The study group consisted of 151 pts and 57 healthy donors (HD).

RESULTS

JAK2V617F mutation was found in 96.7% (146/151) of the studied pts. JAK2 exon 12 mutations were identified in 2 individuals. The coexistence of JAK2V617F and JAK2 exon 12 mutation was confirmed in 2 other pts. In one case, neither JAK2V617F nor JAK2 exon 12 mutation was found. The presence of ten different non-driver mutations (ASXL1, SRSF2, U2AF1, IDH2) in eight of the analyzed pts (5.3%) was confirmed. The overall frequency of thrombotic events (TE) in the studied PV group was 23.8% (36/151). In patients with TE, median platelet count was lower than in pts without TE. Thrombotic risk did not depend on JAK2 rs12343867, TERT rs2736100, OBFC1 rs9420907 SNV, however, we found a novel strong tendency towards statistical significance between the CC genotype miR-146a rs2431697 and thrombosis. The disease progression to fibrotic phase was confirmed in 9% of the pts. Fibrotic transformation in PV pts was affected mainly by JAK2V617F variant allele frequency (VAF) and the presence of coexisting non-driver variants. The high JAK2V617F VAF and elevated white blood cell (WBC) count at the time of diagnosis were associated with an increased risk of death.

CONCLUSION

Therefore, in our opinion, complex, laboratory and genetic PV pts evaluation at the time of diagnosis should be incorporated into a new prognostic scoring system to more precisely define the PV prognosis and to optimize the therapeutic decision-making process.

Cytoreductive treatment in real life: a chart review analysis on 1440 patients with polycythemia vera

Purpose

Patients with polycythemia vera (PV) show an elevated incidence of thromboembolic complications and decreased survival when compared to age-matched healthy individuals. Hypercellularity as indicated by elevated hematocrit, pathophysiological changes induced by the JAK2 driver mutation and cardiovascular risk factors contribute to the increased incidence of thromboembolic events. Higher age and a history of thromboembolic events define a high-risk population of PV patients. Depending on the individual risk profile, phlebotomy or pharmacologic cytoreduction is recommended in combination with low-dose acetylsalicylic acid. Stringent cytoreduction is required for effective risk reduction. However, in recent reports, the rate of thromboembolic complications in PV patients under cytoreductive therapy appears still elevated compared to healthy individuals. This study reports on a chart review to assess for cytoreductive therapy of 1440 PV patients in real life.

Methods

Forty-two eligible hematologists/oncologists in private practice treating patients with MPN were recruited to participate in a paper–pencil-based survey conducted between January 2019 and March 2020 in Germany. Physicians were asked to report primary documented data obtained from patient charts. Descriptive analyses were conducted to assess for patient characteristics, treatment modalities, risk factors and thromboembolic complications.

Results

Data were collected from the patient charts of 1440 individuals diagnosed with PV. The patient population was older than those reported in multicenter trials with a median age of 72.2 years at the time of reporting and 63.5 years at diagnosis. Age was the main factor accounting for high-risk status with 84.7% of patients being above the age of 60 followed by thromboembolic complications reported in 21.3% of patients. The use of pharmacologic cytoreduction was highly variable between participating centers with an average of 60.7% and a range of 10.1–100%. Hydroxyurea was the most frequently used drug followed by ruxolitinib, while interferons were reported for a minority of patients. For 35.4% of patients a persistent need for phlebotomy in addition to cytoreductive treatment was reported. Although presence of high-risk criteria and insufficient disease control were reported as main triggers to initiate pharmacologic cytoreduction, 28.1% had elevated hematocrit values (> 45%) and 38.6% showed persistence of elevated leukocyte count (> 10^9/l) while on cytoreductive treatment. In contrast, physician-reported symptom burden was lower than published in clinical trials and patient-reported outcomes. The rate of patients experiencing thromboembolic complications was 32.2% at any time and 14.3% after diagnosis with most patients receiving acetylsalicylic acid and 10.8% remaining on oral anticoagulants or heparin.

Conclusions

Cytoreductive treatment of high-risk PV in real life is highly variable regarding indication for cytoreduction and definition of therapy resistance. This study highlights the need for (i) improved risk stratification for thromboembolic events, (ii) consequent indication of pharmacologic cytoreduction in high-risk PV and (iii) attention to signs of therapy resistance that can trigger an earlier and stringent switch to second line agents.

Bilateral Osteonecrosis of the Capitate: A Case Report

CASE

We report a case of bilateral capitate osteonecrosis in a patient who has a history of acute lymphocytic leukemia treated with systemic steroids and other chemotherapeutic agents. After exhausting conservative treatment, the patient underwent surgical management with a right-sided 4-corner arthrodesis and left-sided vascular pedicle graft, providing pain relief and improved function.

CONCLUSION

In patients with a history of hematologic malignancy, clinicians should consider osteonecrosis of the capitate as a cause of wrist pain. Salvage procedures and vascularized grafts can provide pain relief in the presence of both early and late capitate osteonecrosis or collapse.

Thrombotic and hemorrhagic events in 2016 World Health Organization-defined Philadelphia-negative myeloproliferative neoplasm

BACKGROUND/AIMS

Recent changes in the diagnostic criteria for myeloproliferative neoplasms (MPNs) and increasing patient numbers necessitate updating of the data on vascular events in patients with such disorders.

METHODS

In this single-center study, thrombotic and hemorrhagic events were retrospectively analyzed in patients diagnosed with essential thrombocythemia (ET), polycythemia vera (PV) prefibrotic/early primary myelofibrosis (pre-PMF), or PMF, based on the 2016 World Health Organization diagnostic criteria.

RESULTS

Of a total of 335 consecutive patients (139 ET, 42 pre-PMF, 124 PV, and 30 PMF patients; 192 males and 143 females) of median age 64 years (range, 15 to 91), 112 (33.4%) experienced a total of 126 thrombotic events before diagnosis, at the time of diagnosis, or during follow-up over a median of 4.6 years (range, 0.1 to 26.5). Cerebrovascular thrombosis (18.8%) was the most common initial event, followed by coronary heart disease (10.1%) and splanchnic (1.5%) and peripheral thrombosis (1.5%). Arterial thrombosis was more common than venous thrombosis (31.3% vs. 2.1%, respectively; p = 0.001). Thrombosis was most frequent in PV patients (39.5%), followed by patients with pre-PMF (38.1%), ET (30.9%), and PMF (13.3%). Of the 112 patients who experienced thromboses, 53 (47%) and 39 (33.9%) had thrombotic events before and at the time of MPN diagnosis, respectively. Twenty-seven patients (8.1%) experienced 29 hemorrhagic events, of which gastrointestinal bleeding (n = 20) was the most common.

CONCLUSION

Most thrombotic events occurred before or at the time of diagnosis, and the prevalence of arterial thrombosis was markedly higher than that of venous thrombosis in patients with MPN.

Evaluation of the need for cytoreduction and its potential carcinogenicity in children and young adults with myeloproliferative neoplasms

Myeloproliferative neoplasms are rare at a young age, and few reports have described the disease characteristics and outcomes in this group. This study aimed to elucidate the clinical course of essential thrombocythemia (ET) and polycythemia vera (PV) in children and young adults aged <39 years focusing on thromboembolic events (TE) and second primary malignancies (SPMs). A total of 990 patients who were diagnosed from 2008 to 2017 were included by analyzing the Health Insurance Review and Assessment Service database in Korea. The incidence was 2.53 per 1,000,000 for ET (643 patients; 276 male patients; median 31 years) and 1.37 per 1,000,000 for PV (347 patients; 309 male patients; median 32 years). Three ET patients developed secondary acute myelogenous leukemia and three developed secondary myelofibrosis. The 5-year cumulative incidence of TE was 14.2% in ET and 21.3% in PV. Thus, the incidence was higher in PV; in particular, arterial TE (ATE) was evidently higher in PV than in ET. The 5-year cumulative incidence of SPMs was 2.5% in ET and 2.6% in PV. While the use of both aspirin and hydroxyurea reduced the incidence of ATE, hydroxyurea significantly increased the incidence of SPMs. The incidence of ET and PV was very low, and ET was more common than PV in children and young adults. The high incidence of TE in young patients suggests the importance of thrombosis prevention. However, hydroxyurea appears to increase the incidence of SPMs; therefore, the risks and benefits should be considered.

Polycythemia Vera Presenting as Hemorrhagic Stroke

Patients with polycythemia vera are at high risk for vaso-occlusive events including cerebral ischemia and hemorrhage. Cerebral ischemic events are due to increased blood viscosity and platelet activation within the central nervous system arterial vessels. We present a case of a 65-year-old woman who presented to the emergency department with seizures followed by left-sided weakness. Hematologic investigations revealed a hyperviscous state, and magnetic resonance imaging (MRI) was consistent with bilateral hemorrhagic infarction. Genetic studies were positive for polycythemia vera mutation. Symptoms improved with phlebotomy and antiplatelet agents. Through this case, we aim to highlight polycythemia vera as a cause of hemorrhagic stroke and the importance of blood counts in the routine evaluation of the same.

Platelet function and blood coagulation system status in childhood essential thrombocythemia

Childhood essential thrombocythemia (ET) is a rare chronic myeloproliferative disorder. The quality of life of ET patients may decrease as a result of ischemic and hemorrhagic complications of unclear origin. Our goal was to characterize the hemostatic system in children with ET. We genotyped and investigated blood samples from 20 children with ET in a prospective case series study using platelet aggregation, functional flow cytometry (FC) assay and standard clotting assays. Three children had a JAK2V617F mutation, 4 had mutations in CALR and 13 were triple-negative. Myelofibrosis in stage 1-2 was detected in 3 children. Three patients had bleeding episodes and seven had ischemic events. Aggregation in response to collagen, adenosine diphosphate, and ristomycin was decreased in all patients. In FC, significant changes in the whole patient group compared to the healthy children control group were decrease in the resting forward scatter and PAC1 binding (activated GPIIb/IIIa) level. For the activated platelets, dense granules release (by mepacrine), PAC1, and GPIIb/IIIa levels were significantly decreased. GPIb/V/IX, P-selectin, and phosphatidylserine levels manifested only moderate differences. Forward and side scatter changes in response to stimulation (representing shape change) and dense granules release were significantly lower in the 3 patients with bleeding than in the 17 patients without hemorrhage. Activated partial thromboplastin time was slightly prolonged, prothrombin index was slightly shortened and thrombin time was normal, while fibrinogen was mildly decreased in the ET patients. It could be concluded that the observed platelet function defects could be related to bleeding in ET, and be potentially used as a marker.

Hemorrhage in Essential Thrombocythemia or Polycythemia Vera: Epidemiology, Location, Risk Factors, and Lessons Learned from the Literature

Hemorrhage is a well-known complication of essential thrombocythemia (ET) and polycythemia vera (PV), but evidence-based data on its management and prevention are lacking to help inform clinicians. In this review, appropriate published data from the past 15 years regarding bleeding epidemiology, classification, location, and risk factors are presented and discussed. Research was conducted using the Medline database. The bleeding classifications were heterogeneous among the collected studies. The median incidences of bleeding and major bleeding were 4.6 and 0.79% patients/year, in ET patients and 6.5 and 1.05% patients/year in PV patients, respectively. The most frequent location was the gastrointestinal tract. Bleeding accounted for up to 13.7% of deaths, and cerebral bleeding was the main cause of lethal hemorrhage. Thirty-nine potential risk factors were analyzed at least once, but the results were discrepant. Among them, age >60 years, bleeding history, splenomegaly, myeloproliferative neoplasm subtype, and platelet count should deserve more attention in future studies. Among the treatments, aspirin seemed to be problematic for young patients with ET (especially CALR-mutated ET patients) and anagrelide was also identified as a bleeding inducer, especially when associated with aspirin. Future studies should analyze bleeding risk factors in more homogeneous populations and with common bleeding classifications. More tools are needed to help clinicians manage the increased risk of potentially lethal bleeding events in these diseases.

Essential thrombocythemia: a hemostatic view of thrombogenic risk factors and prognosis

Essential thrombocythemia (ET) is a classical myeloproliferative neoplasm that is susceptible to hypercoagulable state due to impaired hemostatic system, so that thrombotic complications are the leading cause of mortality in ET patients. The content used in this article has been obtained by the PubMed database and Google Scholar search engine from English-language articles (2000-2019) using the following keywords: "Essential thrombocythemia," "Thrombosis," "Risk factors" and "Hemostasis. In this neoplasm, the count and activity of cells such as platelets, leukocytes, endothelial cells, as well as erythrocytes are increased, which can increase the risk of thrombosis through rising intercellular interactions, expression of surface markers, and stimulation of platelet aggregation. In addition to these factors, genetic polymorphisms in hematopoietic stem cells (HSCs), including mutations in JAK2, CALR, MPL, or genetic abnormalities in other genes associated with the hemostatic system may be associated with increased risk of thrombotic events. Moreover, disruption of coagulant factors can pave the way for thrombogeneration. Therefore, the identification of markers related to cell activation, genetic abnormalities, or alternation in the coagulant system can be used together as diagnostic and prognostic markers for the occurrence of thrombosis among ET patients. Thus, because thrombotic complications are the main factors of mortality in ET patients, a hemostatic viewpoint and risk assessment of cellular, genetic, and coagulation factors can have prognostic value and contribute to the choice of effective treatment and prevention of thrombosis.

Thrombophilic Risk of Factor V Leiden, Prothrombin G20210A, MTHFR, and Calreticulin Mutations in Essential Thrombocythemia Egyptian Patients

Objectives

Essential thrombocythemia (ET) is one of the myeloproliferative neoplasms characterized by a sustained elevation of platelet numbers with a tendency for thrombosis and hemorrhage. The aim of this work is to establish the relation between calreticulin, factor V Leiden, prothrombin G20210A, and MTHFR mutations in ET patients and the thrombotic risk of these patients.

Methods

This study was carried out on 120 ET patients and 40 apparently healthy individuals as a control group.

Results

There were increases in WBCs, PLT counts, PT, fibrinogen concentration factor V Leiden, and MTHFR mutation in ET patients as compared to the control group (P < 0.05). Also, there were increases in WBCs, PLT counts, and hematocrit value in thrombosed ET patients as compared to the nonthrombosed ones (P < 0.05). On the contrary, there was no significantly statistical difference in ET patients with JAK2 V617F positive mutation versus the JAK2 negative group (P > 0.05) and in patients with cardiovascular risk factors versus patients with noncardiovascular risk factors (P > 0.05). ET patients with factor V Leiden, prothrombin gene, and CALR mutations were more prone to thrombosis (odds ratio 5.6, 5.7 and 4.7, respectively). On the contrary, JAk2V 617F and MTHFR mutations have no effect on the thrombotic state of those patients.

Conclusion

There is a significant increase risk of thrombosis in ET patients with CALR mutation, thrombophilic mutations, as well as factor V Leiden and prothrombin gene mutation with a risk of developing leukemic transformation.

Acute multiple cerebral infarction combined with cerebral microhemorrhage in Polycythemia vera: A case report

Polycythemia vera (PV) is one of the rare causes of cerebrovascular disease, whose common manifestations in the nervous system are cerebral infarction and transient ischemic attack. A number of cases of PV patients with bleeding complicated with subdural hemorrhage or cerebral hemorrhage have been previously reported. However, sometimes PV patient with complicated cerebral hemorrhage and lower extremity venous thrombosis have been admitted to the People's Hospital of Liaoning Province. The present case study reports on a patient with acute multiple cerebral infarction with cerebral micro-hemorrhage associated with PV, who was not treated with anti-thrombosis treatment. After bloodletting treatment and hydroxyurea treatment, the patients condition was stable and they were discharged. A possible mechanism of infarction is that PV may cause abnormal proliferation of red blood cells, white blood cells and platelets in the circulation, resulting in an increase of blood viscosity and reduction of blood flow velocity. Platelet deficiency may cause abnormal blood coagulation function, which may be the reason for the blood and thrombotic diseases in patients with PV.

Thromboembolic events in polycythemia vera

Thromboembolic events and cardiovascular disease are the most prevalent complications in patients with polycythemia vera (PV) compared with other myeloproliferative disorders and are the major cause of morbidity and mortality in this population. Moreover, a vascular complication such as arterial or venous thrombosis often leads to the diagnosis of PV. The highest rates of thrombosis typically occur shortly before or at diagnosis and decrease over time, probably due to the effects of treatment. Important risk factors include age (≥ 60 years old) and a history of thrombosis; elevated hematocrit and leukocytosis are also associated with an increased risk of thrombosis. The goal of therapy is to reduce the risk of thrombosis by controlling hematocrit to < 45%, a target associated with reduced rates of cardiovascular death and major thrombosis. Low-risk patients (< 60 years old with no history of thrombosis) are managed with phlebotomy and low-dose aspirin, whereas high-risk patients (≥ 60 years old and/or with a history of thrombosis) should be treated with cytoreductive agents. Interferon and ruxolitinib are considered second-line therapies for patients who are intolerant of or have an inadequate response to hydroxyurea, which is typically used as first-line therapy. In this review, we discuss factors associated with thrombosis and recent data on current treatments, including anticoagulation, highlighting the need for more controlled studies to determine the most effective cytoreductive therapies for reducing the risk of thrombosis in patients with PV.

A systematic review and meta-analysis of the prevalence of thrombosis and bleeding at diagnosis of Philadelphia-negative myeloproliferative neoplasms

BACKGROUND

Philadelphia (Ph) chromosome-negative myeloproliferative neoplasms (MPNs) are a heterogeneous group of hematopoietic stem cell clonal diseases. Most patients with MPN are asymptomatic at diagnosis although some of them suffer from constitutional symptoms. Thrombosis and bleeding can also be one of the initial manifestations although the reported prevalence varied considerably across the studies. This systematic review and meta-analysis was conducted with the aims to better understand the prevalence and characteristics of thrombosis and bleeding among patients with newly-diagnosed MPN.

METHODS

Using a search strategy that included the terms for myeloproliferative neoplasms, thrombosis, and bleeding, two investigators independently searched for published articles indexed in the MEDLINE and EMBASE databases from inception to August 2018. The pooled prevalence was calculated using the DerSimonian-Laird random-effects model with a double arcsine transformation.

RESULTS

A total of 29 cohort studies (8 prospective and 21 retrospective) with 13,436 patients with MPN were included into this meta-analysis. At diagnosis, the pooled prevalence of overall thrombosis among patients with MPN was 20.0% (95% CI, 16.6-23.8%; I2 96%), with the pooled prevalence of arterial thrombosis of 16.2% (95% CI, 13.0-20.0%; I2 95%) and the pooled prevalence of venous thrombosis of 6.2% (95% CI, 4.9-7.8%; I2 89%). Common thrombotic events included cerebrovascular disease/transient ischemic attack, coronary heart disease, and deep venous thrombosis. The pooled prevalence of hemorrhagic complications among patients who were newly diagnosed with MPN patients was 6.2% (95% CI, 5.0-7.8%; I2 85%). Common sites of bleeding included gastrointestinal, mucosal, and cutaneous bleeding.

CONCLUSIONS

Thrombosis and bleeding are common initial manifestations of MPN. Investigations for MPN should be considered for patients who present with unexplained thrombosis or abnormal bleeding.

Developments in diagnosis and treatment of essential thrombocythemia

INTRODUCTION

Essential thrombocythemia (ET) is a chronic myeloproliferative neoplasm characterized by thrombocytosis, increased risk of thrombotic/hemorrhagic events and clonal evolution into blast phase or myelofibrosis. Areas covered: The authors will discuss biology, diagnosis, prognosis, therapy, and outcome of ET. An accurate molecular-morphologic assessment is necessary in order to properly establish diagnosis and prognosis of ET. Stratification for thrombosis prediction is essential, and IPSET-t model is widely applied. The current treatment strategy is directed to lower the rate of vascular events using cytoreduction in patients at high risk. Prophylactic low dose aspirin indication is more uncertain. To date, therapies for patients who are resistant or intolerant to first-line treatments are scarce. Overall, life expectancy indicates an indolent disease, but IPSET model helps in predicting survival at the time of diagnosis. Expert opinion: Challenging for the future will be to share criteria for ET diagnosis with the community. New insights into the molecular pathogenesis of the disease will improve the prediction of clonal evolution and outcome, and lead to the use of disease-modifying treatments.

Clinico-hematological profile and thrombotic/hemorrhagic events in 150 chinese patients with essential thrombocythemia

Essential thrombocythemia (ET) is an uncommon chronic myeloproliferative disorder with no cure. Patients with ET are at risk of different complications, and currently there are no optimal prognostic standards to predict severe post-diagnosis complications such as thrombosis and hemorrhage. In this study, we retrospectively analyzed the full set of clinical data from 150 Chinese patients with ET enrolled from 2013 to 2016. We discovered that neutrophil-to-lymphocyte ratio (NLR), along with other known clinical parameters such as age, leukocyte count, incidence of thrombotic events is higher in patients with JAK2 V617F mutation. NLR is also higher in patients at high-risk stratification of thrombosis. Multivariate analysis showed that age (P = 0.001, 95% CI 1.023-1.089) and JAK2 V617F mutation (P = 0.003, 95% CI 1.837-21.035) were independent factors for thrombotic events, while age (P = 0.005, 95% CI 1.019-1.111) was the only predictive factor for hemorrhagic events at diagnosis. For future thrombotic events, multivariate analysis revealed NLR as the best predictive parameter (P < 0.001, 95% CI 1.173-1.486) when compared with other clinical parameters such as age (P = 0.037, 95% CI 1.004-1.126), thrombosis at diagnosis (P = 0.036, 95% CI 1.077-9.099) and WBC count (P = 0.047, 95% CI 1.001-1.109). Further ROC curve and Kaplan Meier analysis validated NLR as better prognostic marker for future thrombotic events and thrombosis-free survival. In summary, our data suggest that NLR parameter may possess great prognostic significance for future thrombosis in ET patients.

Assessing the thrombotic risk of patients with essential thrombocythemia in the genomic era

The molecular characterization of myeloproliferative neoplasms, including essential thrombocythemia (ET), has enabled deeper understanding of their pathogenesis. A driver lesion, namely, Janus kinase (JAK)2V617F, calreticulin (CALR) or myeloproliferative leukemia (MPL) gene mutation can be identified in the vast majority of patients. Each of these mutations is associated with distinct clinical features and may modulate the patients' clinical course, risk of complications, including vascular events, and survival. JAK2V617F appears to be a risk-modifying mutation and has been shown to increase the likelihood of thrombotic events in patients with ET across studies. As such, it has been included in prognostic models and its presence may influence treatment decisions. The association of CALR and MPL mutations with the incidence of vascular events has been less clear. Even more limited information is available on the contribution of additional non-driver lesions to the thrombotic risk. In this review we discuss the available evidence on the role of recurrent mutations in the risk of thrombotic complications in patients with ET and how these mutations weigh into modern prognostic scores.