Essential thrombocythemia in young individuals: frequency and risk factors for vascular events and evolution to myelofibrosis in 126 patients

Essential thrombocythaemia: A contemporary approach with new drugs on the horizon

Essential thrombocythaemia (ET) is a myeloproliferative neoplasm characterized by an increased risk of vascular complications and a tendency to progress to myelofibrosis and acute leukaemia. ET patients have traditionally been stratified into two thrombosis risk categories based on age older than 60 years and a history of thrombosis. More recently, the revised IPSET-thrombosis scoring system, which accounts for the increased risk linked to the JAK2 mutation, has been incorporated into most expert recommendations. However, there is increasing evidence that the term ET encompasses different genomic entities, each with a distinct clinical course and prognosis. Moreover, the effectiveness and toxicity of cytoreductive and anti-platelet treatments differ depending on the molecular genotype. While anti-platelets and conventional cytoreductive agents, mainly hydroxycarbamide (hydroxyurea), anagrelide and pegylated interferon, remain the cornerstone of treatment, recent research has shed light on the effectiveness of novel therapies that may help improve outcomes. This comprehensive review focuses on the evolving landscape of treatment strategies in ET, with an emphasis on the role of molecular profiling in guiding therapeutic decisions. Besides evidence-based management according to revised IPSET-thrombosis stratification, we also provide specific observations for those patients with CALR-, MPL-mutated and triple-negative ET, as well as cases with high-risk mutations.

Tamoxifen for the treatment of myeloproliferative neoplasms: A Phase II clinical trial and exploratory analysis

Current therapies for myeloproliferative neoplasms (MPNs) improve symptoms but have limited effect on tumor size. In preclinical studies, tamoxifen restored normal apoptosis in mutated hematopoietic stem/progenitor cells (HSPCs). TAMARIN Phase-II, multicenter, single-arm clinical trial assessed tamoxifen's safety and activity in patients with stable MPNs, no prior thrombotic events and mutated JAK2V617F, CALRins5 or CALRdel52 peripheral blood allele burden ≥20% (EudraCT 2015-005497-38). 38 patients were recruited over 112w and 32 completed 24w-treatment. The study's A'herns success criteria were met as the primary outcome ( ≥ 50% reduction in mutant allele burden at 24w) was observed in 3/38 patients. Secondary outcomes included ≥25% reduction at 24w (5/38), ≥50% reduction at 12w (0/38), thrombotic events (2/38), toxicities, hematological response, proportion of patients in each IWG-MRT response category and ELN response criteria. As exploratory outcomes, baseline analysis of HSPC transcriptome segregates responders and non-responders, suggesting a predictive signature. In responder HSPCs, longitudinal analysis shows high baseline expression of JAK-STAT signaling and oxidative phosphorylation genes, which are downregulated by tamoxifen. We further demonstrate in preclinical studies that in JAK2V617F+ cells, 4-hydroxytamoxifen inhibits mitochondrial complex-I, activates integrated stress response and decreases pathogenic JAK2-signaling. These results warrant further investigation of tamoxifen in MPN, with careful consideration of thrombotic risk.

Preservation of fertility in female patients with hematologic diseases

Recent developments of assisted reproduction techniques turned possible to avoid the infertility consequences of oncologic treatments, but fertility preservation (FP) has been somewhat neglected in women with hematologic diseases undergoing gonadotoxic treatments. For these specific cases, the current options for FP include the cryopreservation of embryos, mature oocytes and ovarian tissue, and oocyte in-vitro maturation. We intend to make patients and clinicians aware of this important and relevant issue, and provide hematologists, assisted reproduction physicians and patients, with updated tools to guide decisions for FP. The physicians of the units responsible for female FP should always be available to decide on the best-individualized FP option in strict collaboration with hematologists. With a wide range of options for FP tailored to each case, a greater level of training and information is needed among clinicians, so that patients proposed to gonadotoxic treatments can be previously advised for FP techniques in hematological conditions. ABBREVIATED ABSTRACT: Recent developments of assisted reproduction techniques turned possible to preserve the fertility of women with hematologic diseases undergoing gonadotoxic treatments. Current options for fertility preservation in women with hematologic diseases are presented. It is imperative to offer fertility preservation to all women before starting any gonadotoxic treatment and in some cases after treatment. Fertility preservation methods enable to later achieve the desired pregnancy.

Essential thrombocytosis: diagnosis, differential diagnosis, complications and treatment considerations of relevance for a cardiologist

Essential thrombocytosis (ET) is a rare haematological malignancy, with an incidence rate of 1.5-2.5/100,000 per year. For many patients with ET the first manifestation of their underlying disease is a thrombotic or haemorrhagic complication. A recent retrospective study revealed an incidence rate of at least 2.1% in people under 40 years presenting with an acute coronary syndrome, although the diagnosis was initially missed in all cases. Thus, cardiologists face a much higher than average incidence rate of ET in their daily practice, but seem insufficiently aware of the disease. The current review summarises symptoms, (differential) diagnosis, complications and treatment considerations of ET of relevance for a cardiologist. Typical symptoms, besides thrombosis and haemorrhage, include erythromelalgia and aquagenic pruritus, while platelets > 450 × 109/l are a diagnostic for ET once other myeloproliferative neoplasms, secondary and spurious thrombocytosis have been excluded. With regard to treatment, timing of revascularisation depends on the presence of ischaemia and concurrent platelet counts. In the presence of ischaemia, revascularisation should not be delayed and adequate platelet counts can be achieved by platelet apheresis. In the absence of ischaemia, revascularisation can be delayed until adequate platelet counts have been achieved by cytoreductive therapies. Cardiologists should be aware of/screen for possible ET.

Thrombosis in Pregnant Women with Hematological Malignancies: A Case-Based Review

Cancer and pregnancy induce a procoagulant environment which may lead to maternal and fetal complications, such as venous thromboembolism, fetal growth restriction, and fetal loss. The incidence of hematological malignancies diagnosed during pregnancy is rising, and thrombotic events in such malignancies are not rare. Management of thrombosis during pregnancy poses a therapeutic challenge, that is further exacerbated by the impact of cancer. The available data on managing pregnant women with hematological malignancies are limited to those with myeloproliferative neoplasms, mainly essential thrombocythemia, and, to a lesser extent, polycythemia vera. Low-dose aspirin is recommended throughout pregnancy, and considering treatment with low-molecular-weight heparin and interferon formulations is advised for high-risk patients. Currently, guidelines for handling thrombotic events in pregnant women with lymphoma or leukemia are lacking, and their management is based on data extrapolated from retrospective studies, and guidelines for prevention and treatment of cancer-associated thrombosis. The present case-based review will focus on the complex issue of thrombotic risk in pregnant women with hematological malignancies, specifically myeloproliferative neoplasms, lymphomas, and leukemias.

Essential Thrombocytosis in Patients <40 Years Old With Acute Coronary Syndromes: A Not So Uncommon Underlying Diagnosis Often Overlooked

BACKGROUND

In patients under <40 years, traditional cardiovascular (CV)-risk factors are a less likely cause of acute coronary syndromes (ACS) compared to older counterparts.

AIMS

To estimate the prevalence of essential thrombocytosis (ET), a hematological disorder and less-prevalent risk factor, in young patients presenting with ACS.

METHODS

We constructed a retrospective database of all patients <40 years (n=271) that had consecutively undergone coronary angiography (CAG) after their first ACS within our hospital within the last ten years (2010-2020) and had known thrombocyte counts (n=241). Patients with thrombocytes >450x10*9/L were screened for this hematological disorder.

RESULTS

In our database, we identified 15 subjects with thrombocytosis. One was previously known as ET. Of the remaining 14 patients, five were considered reactive/secondary thrombocytosis, and four were lost to follow-up, four were eventually diagnosed with ET, one remains uncertain. The diagnosis was newly established before the initiation of this study in two patients (average delay: six years). Two patients were identified as a result of this study.  Conclusion: With a prevalence of at least 2.1%, ET appears not uncommon in patients <40 years with ACS. Moreover, screening patients with ACS and elevated thrombocytes yielded a novel diagnosis of ET in 27% of patients. The diagnosis was initially missed in all cases. Since the timing of revascularization should be adjusted to thrombocyte count/initiation of ET therapy to prevent thrombotic complications, cardiologists should know, recognize and screen for this pathology in ACS-patients, notably in those with absent traditional CV-risk factors: an 'ACS-protocol' aimed at less-prevalent risk factors could support this.

Acute Limb Ischemia in the Young: A Rare Case of Essential Thrombocytosis

Acute limb ischemia (ALI) is rarely observed in young populations. The hypercoagulable state is a notable cause of ALI other than artery disease progression and cardiac embolization. A hypercoagulable state occurs in essential thrombocytosis because of the overproduction of hematopoietic cells secondary to the mutation of the JAK2, CALR, or MPL genes. We report a rare case of a 37-year-old woman presenting with Rutherford IIA ALI in the left lower extremity. Laboratory data revealed she had a platelet count reaching up to 1.38 mil/μL, with other blood profiles being normal. A JAK2 mutation examination was later performed and proved positive. After careful management with catheter-directed thrombolysis, surgical thrombectomy, and cytoreductive therapy using hydroxyurea, the symptoms subsided and eventually restored the patient to physical activity in less than one month.

Correlation between leukocyte-platelet aggregates and thrombosis in myeloproliferative neoplasms

INTRODUCTION

The impact of activated blood and endothelial cells on the thrombosis in myeloproliferative neoplasms (MPN) has not yet been clarified. We prospectively analyzed correlation between circulating leukocyte-platelet aggregates and soluble selectins to thrombosis occurrence in MPN, in the context of standard and cardiovascular risk factors, and different clinical and biological characteristics.

METHODS

Flow cytometric analysis of neutrophil-platelet (Neu-Plt) and monocyte-platelet (Mo-Plt) aggregates in peripheral blood, as well as quantification of soluble E-/L-/P-selectins by enzyme immunoassay, was performed on 95 newly diagnosed MPN patients.

RESULTS

During the follow-up, thrombosis occurred in 12.6% MPN patients (arterial 9.4%, venous 3.2%), with a mean time of 39 months. The overall incidence rate of main thrombotic events was 4.36 per 100 patient-years. The incidence of arterial hypertension (HTA) was significantly higher in patients with thrombosis, compared to those without thrombosis (P < .05). The level of soluble P-selectin was significantly higher in patients with thrombosis compared to those without thrombosis (346.89 ng/mL vs 286.39 ng/mL, P = .034). The mean level of Neu-Plt (26.7% vs 22.4%) and Mo-Plt (17.8% vs 12.3%) aggregates did not differ significantly between the groups with and without thrombosis. A multivariate COX proportional hazard regression model confirmed an independent predictive significance of Mo-Plt aggregates (HR = 1.561, 95% CI: 1.007-2.420, P = .046), as well as the cumulative effect of Mo-Plt aggregates and HTA (HR = 1.975, 95%CI: 1.215-3.212, P = .006) for thrombosis occurrence.

CONCLUSION

Monocyte-platelet aggregates represent an independent risk factor for thrombosis occurrence, further on supported by HTA.

Philadelphia chromosome-negative myeloproliferative neoplasms in younger adults: A critical discussion of unmet medical needs, with a focus on pregnancy

Myeloproliferative neoplasms (MPN) are traditionally regarded as a disease of older adults, though a not negligible fraction of cases occurs at a younger age, including women of childbearing potential. MPN in younger patients, indeed, offer several challenges for the clinical hematologist, that goes from difficulties in reaching a timely and accurate diagnosis to a peculiar thrombotic risk, with a relatively high incidence of thromboses in unusual sites (as the splanchnic veins or the cerebral ones). Moreover, the issue of pregnancy is recently gaining more attention as maternal age is rising and molecular screening are widely implemented, leading to a better recognition of these cases, both before and during pregnancy. In the present work we aim at discussing four clinical topic that we identified as areas of uncertainty or true unmet medical needs in the management of younger patients with MPN, with a particular focus on the topic of pregnancy. For each of these topics, we critically reviewed the available evidence that support treatment decisions, though acknowledging that recommendations in this field are mostly based on expert opinion or derived from guidelines of other clinical conditions that share with MPN a high vascular risk, as antiphospholipid syndrome. Taking into consideration both the lack of evidence-based data and the clinical heterogeneity of MPN, we support an individualized strategy of counseling and management for both young patients and for expectant mother with MPN.

Essential Thrombocythemia in Children: A Retrospective Study

Background

Essential thrombocythemia (ET) is one of the “classic” Philadelphia chromosome negative (Ph-) myeloproliferative neoplasms characterized by sustained thrombocytosis, increased megakaryopoiesis and high risk of vascular complications. ET is very rare in childhood. The annual incidence is approximately 1 per 10,000,000 in children less than 14 years, and about 60 times lower than adults. The genetic landscape and clonal features in childhood ET has not been well defined. There is no evidence-based guidance on the diagnosis of childhood ET.

Methods

Medical records of 28 pediatric patients (age ≤ 14 years at diagnosis) with ET were reviewed and evaluated to characterize the different mutation profiles and to evaluate the treatment modalities used and the potential long-term outcome.

Results

More than half of the patients were found to have positive history of parental consanguinity (57.1%) whereas positive family history was documented for more than a quarter of our patients (28.6%). Janus kinase 2 gene (JAK2) V617F mutation was positive in two of 26 patients (7.7%). Myeloproliferative leukemia virus oncogene (MPL) exon 10 and calreticulin (CALR) mutations were tested in eight patients, which were negative for all of them. Treatment included low-dose aspirin (LDA) in seven patients (50%), combination of LDA with hydroxyurea in three patients (21.4%), hydroxyurea in two patients (14.3%), combination of platelets apheresis with LDA and anagrelide in one patient each (7.1%). During the treatment, two patients experienced stroke (7.1%), one patient developed Budd-Chiari syndrome (3.6%) and one patient developed azoospermia (3.6%).

Conclusions

The incidence of ET in children is extremely low in Saudi Arabia. Most of the children with ET were asymptomatic, and thrombocytosis was often discovered incidentally. JAK2 V617F mutation has no known impact on the prognosis or on the outcome of the disease in the pediatric age group that is in contrast to the adult ET. Children less than 1 year are at high risk for complications particularly during acute precipitating infectious episode. The potential complications and clinical course of pediatric ET are unpredictable.

Clinicopathological spectrum of BCR-ABL-Negative myeloproliferative neoplasms with correlation with janus-associated kinase 2 mutation

Background: Non chronic myelogenous leukemia (non-CML)/BCR-ABL-negative myeloproliferative neoplasms (MPNs) include essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF) (apart from chronic neutrophilic leukemia and chronic eosinophilic leukemia, which are rare). They are uncommon clonal disorders of adults, with an incidence ranging from 0.5 to 3/100,000 persons, BCR-ABL negative, and characterized by the activation of Janus-associated kinase 2 (JAK2). Very few studies have been reported from India. Aims and Objectives: The aims and objectives of this study were to analyze the clinicopathological spectrum and to determine the frequency of JAK2 mutation in patients of non-CML/BCR-ABL negative MPNs. Materials and Methods: Clinical and morphological features and frequency of JAK2 mutation in patients with PV, ET, and PMF were studied at a tertiary care hospital. The material was retrieved from the hematopathology records and reviewed. Results: JAK2V617F mutation was found in 10 of 14 cases (71%) of MPNs, 100% in PV, 50% in ET, and 71% of idiopathic myelofibrosis. The presence of JAK2V617F mutation was associated with a higher hemoglobin level (P < 0.05), a higher TLC (P < 0.05), and higher age (P < 0.05). Results showed that there are morphologic differences, and megakaryocytic morphology represents a useful clue for the differential diagnosis of these three BCR-ABL-negative MPN subtypes. Conclusion: The JAK2 V617F mutation was detected in 71% of patients with MPN disorders. Peripheral blood mutation screening for JAK2 V617F should be incorporated into the initial evaluation of patients suspected to have MPNs. Differences in megakaryocytic morphology provide the histomorphological hallmark of BCR-ABL-negative MPN subtypes.

A Broad Overview of Signaling in Ph-Negative Classic Myeloproliferative Neoplasms

Simple Summary

There is growing evidence that Ph-negative myeloproliferative neoplasms are disorders in which multiple signaling pathways are significantly disturbed. The heterogeneous phenotypes observed among patients have highlighted the importance of having a comprehensive knowledge of the molecular mechanisms behind these diseases. This review aims to show a broad overview of the signaling involved in myeloproliferative neoplasms (MPNs) and other processes that can modify them, which could be helpful to better understand these diseases and develop more effective targeted treatments.

Abstract

Ph-negative myeloproliferative neoplasms (polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF)) are infrequent blood cancers characterized by signaling aberrations. Shortly after the discovery of the somatic mutations in JAK2, MPL, and CALR that cause these diseases, researchers extensively studied the aberrant functions of their mutant products. In all three cases, the main pathogenic mechanism appears to be the constitutive activation of JAK2/STAT signaling and JAK2-related pathways (MAPK/ERK, PI3K/AKT). However, some other non-canonical aberrant mechanisms derived from mutant JAK2 and CALR have also been described. Moreover, additional somatic mutations have been identified in other genes that affect epigenetic regulation, tumor suppression, transcription regulation, splicing and other signaling pathways, leading to the modification of some disease features and adding a layer of complexity to their molecular pathogenesis. All of these factors have highlighted the wide variety of cellular processes and pathways involved in the pathogenesis of MPNs. This review presents an overview of the complex signaling behind these diseases which could explain, at least in part, their phenotypic heterogeneity.

Essential Thrombocythemia and Acquired von Willebrand Syndrome: The Shadowlands between Thrombosis and Bleeding

Over the past decade, new insights have emerged on the pathophysiology of essential thrombocythemia (ET), its clinical management, and associated thrombohemostatic disturbances. Here, we review the latest diagnostic and risk stratification modalities of ET and its therapeutics. Moreover, we discuss the clinical evidence-based benefits, deriving from major clinical trials, of using cytoreductive therapy and antiplatelet agents to lower the risk of fatal vascular events. Also, we focus on the condition of extreme thrombocytosis (>1000 × 10⁹/L) and bleeding risk, the development and pathogenesis of acquired von Willebrand syndrome, and the clinical approach to this paradoxical scenario in ET.

Natural history of polycythemia vera and essential thrombocythemia presenting with splanchnic vein thrombosis

Patients with polycythemia vera (PV) or essential thrombocythemia (ET) presenting with splanchnic vein thrombosis (SVT) might have a specific clinico-biological profile. To investigate this hypothesis, 3705 PV/ET patients from three national registers, 118 of them presenting with SVT, were reviewed. After correction for age and sex, PV/ET patients with SVT showed an increased risk of death (HR 2.47, 95% CI 1.5-4.01, p < 0.001), venous thrombosis (IRR 3.4, 95%CI 2.1-5.5, p < 0.001), major bleeding (IRR 3.6, 95%CI 2.3-5.5, p < 0.001), and second cancer (IRR 2.37, 95%CI 1.4-4.1, p = 0.002). No case of acute leukemia was documented among patients with PV/ET presenting with SVT and seven of them (6%) progressed to myelofibrosis. SVT was not associated with lower risk of MF after correction by age and sex. Patients with SVT more frequently died from complications related to hepatic disease, major bleeding, or second cancer, resulting in a 5-year reduction of age- and sex-adjusted median survival. In conclusion, PV and ET patients presenting with SVT have shorter survival than patients with PV and ET of the same age and sex. This excess mortality is related to liver disease, major bleeding, and second cancer rather than to the natural evolution of the MPN.

[Gene mutation spectrum and clinical characteristics analysis of 178 patients with essential thrombocytosis]

目的

分析原发性血小板增多症（ET）患者基因突变谱及临床特征。

方法

对2009年2月1日至2018年11月1日收治的178例初诊ET患者进行回顾性分析。

结果

全部178例患者中，男89例，女89例，中位初诊年龄为49.5（3~86）岁。JAK2V617F基因突变频率为16.45%（1.67%~43.90%），CALR基因突变频率为40.00%（10.00%~49.15%），MPL基因突变频率为25.10%（25.00%~40.00%）。与CALR基因突变的患者相比，JAK2V617F基因突变患者具有较高的发病年龄（P=0.035）、初诊白细胞计数（P=0.040）、初诊血红蛋白浓度（P=0.001）和较低的初诊血小板计数（P=0.002）。47例（27.01%）患者诊断ET前发生血栓事件，3例（1.72%）诊断ET后发生血栓事件。多因素分析结果显示，年龄>60岁（P=0.013，OR=4.595，95%CI1.382~15.282）、心血管危险因素（P<0.001，OR=8.873，95%CI2.921~26.955）为血栓事件的危险因素，CALR基因突变（P=0.032，OR=0.126，95%CI0.019~0.838）为血栓事件的保护性因素。年龄>60岁（P=0.042，OR=4.045，95%CI1.053~15.534）是影响ET患者总生存时间的危险因素。年龄≤60岁、年龄>60岁患者的OS时间分别为（115.231±1.899）、（83.291±4.991）个月（χ²=6.406，P=0.011）。

结论

心血管危险因素、年龄>60岁为ET患者血栓事件的危险因素，CALR基因突变为血栓事件的保护性因素。年龄>60岁是影响ET患者总生存的危险因素。

Posterior reversible encephalopathy syndrome with essential thrombocythemia: A case report

RATIONALE

Posterior reversible encephalopathy syndrome (PRES) is a rare neurological disease of the posterior subcortical white matter that manifests as headache, seizures, visual impairment, disturbance of consciousness, and changes in mental state. While PRES is associated with specific imaging findings involving the posterior circulation area of the brain. In the present study, we report the first case of PRES associated with essential thrombocythemia (ET).

PATIENT CONCERNS

A 49-year-old man suddenly experienced headache, followed by the gradual appearance of consciousness disorders and mental behavior abnormalities. Neurological tests showed that the patient had a Glasgow Coma Scale score of 12, normal muscle strength and tension of the limbs, and was negative for meningeal irritation.

DIAGNOSIS

Magnetic resonance imaging of the brain showed extensive vasogenic edema in the deep white matter of the right cerebellum and the left occipital and temporal lobes and a diagnosis of PRES was considered. Routine blood test showed that his platelet count was markedly increased, and the JAK2 V617F mutation analysis with allele-specific real-time polymerase chain reaction was positive. The bone marrow biopsy indicated an increasing number of megakaryocytes. These findings indicated ET.

INTERVENTIONS

PRES was treated with a dehydrating agent and supportive and symptomatic treatments. Aspirin tablets were prescribed to address the patient's ET.

OUTCOME

After treatment, the abnormal findings on head imaging were completely reversed. His neurological symptoms were completely relieved.

LESSONS

PRES may be correlated with ET; specifically, ET may trigger PRES and be a risk factor for the acute onset of neurological deficits.

[Clinical features and diagnosis of Ph - negative myeloproliferative neoplasms occurring in conjunction with the antiphospholipid syndrome]

Thrombosis is a serious and extremely dangerous disease that has a negative impact on the quality and longevity. Antiphospholipid syndrome (APS) is a pathology characterized by recurring venous, arterial, microvasculature thrombosis, pregnancy pathology with loss of the fetus and the synthesis of antiphospholipid antibodies. A high risk of thrombotic complications is also observed in patients with myeloproliferative neoplasms (MPN). This article presents a description of three clinical cases of Ph - negative myeloproliferative diseases, occurring in conjunction with APS. In all cases, recurrent thrombosis allowed to suspect the presence of two diseases - MPN and APS.

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.

Activation of TF-Dependent Blood Coagulation Pathway and VEGF-A in Patients with Essential Thrombocythemia

Background and objectives: Recent studies suggest that a vascular endothelial growth factor (VEGF-A) may be involved in the thrombotic process by stimulating the expression of tissue factor in vascular endothelial cells. Tissue factor (TF) can also stimulate the transcription of the gene encoding VEGF-A. The relationship between coagulation and angiogenesis in myeloproliferative neoplasms is not fully understood. The aim of this study was to evaluate the concentration of TF in relation to VEGF-A in the blood of patients with essential thrombocythemia (ET). Patients and methods: The study group consisted of 130, newly diagnosed patients with ET (mean age 61 years). The control group consisted of 35 healthy volunteers (mean age 51 years). Concentrations of VEGF-A, TF, and tissue factor pathway inhibitor (TFPI) were analysed using immunoenzymatic methods. TF and TFPI activities were performed using chromogenic assays. Results: The median concentration of TF Ag was 3-fold higher and the TF activity was more than 15-fold higher in ET patients than in normal individuals. There were no statistically significant differences in the TFPI concentration and activity between groups. VEGF-A was significantly increased in patients with ET (p < 0.000001). Analysis of correlations revealed a positive correlation between VEGF-A and TF Ag as well as a positive correlation between VEGF-A and TFPI activity. Conclusions: The simultaneous increase of TF concentration and activity, VEGF-A in the blood of patients with ET, as well as a positive correlation between the concentration of TF and VEGF-A demonstrates the coexistence of TF-dependent coagulation and activation of angiogenesis.

Acute ST-segment Elevation Myocardial Infarction as the First Manifestation of Essential Thrombocytosis

A 36-year-old female with no significant past medical history presented with sudden onset of crushing substernal chest pain. When the emergency medical services (EMS) arrived, she had a cardiac arrest requiring defibrillation two times in the field prior to arriving at the hospital. In the emergency department (ED), the electrocardiogram (ECG) was significant for ST-elevation that suggested acute anterolateral infarct. Her laboratory evaluation also showed a platelet count of 1095 x 10³/ul. Also, her troponin levels were at 0.16 ng/ml at the time of arrival and peaked at 42.8 ng/ml. She immediately underwent a cardiac catheterization which showed 100% occlusion of her left anterior descending (LAD) artery by a thrombus, which was then treated with a thrombectomy and a single drug-eluting stent was placed. Upon further work-up of her thrombocytosis, the patient had a bone marrow biopsy showing megakaryocytic hyperplasia which no evidence of fibrosis. She was tested for Janus kinase 2 (JAK2) mutation which was positive. The patient was diagnosed with essential thrombocytosis (ET) and was started on cytoreduction therapy with hydroxyurea. Her platelet counts responded appropriately and dropped to less than 500 x 10³ at the time of discharge.

Myeloproliferative neoplasms in the young: Mayo Clinic experience with 361 patients age 40 years or younger

Between 1967 and 2017, 361 patients with myeloproliferative neoplasms (MPN), age ≤ 40 years, were seen at our institution, constituting 12% of all MPN patients (n = 3023) seen during the same time period; disease-specific incidences were 12% in polycythemia vera (PV; n = 79), 20% in essential thrombocythemia (ET; n = 219) and 5% in primary myelofibrosis (PMF; n = 63). Compared to their older counterparts, younger patients were more likely to present with low risk disease (P < .001) and display female preponderance in ET (P = .04), lower incidence of arterial events overall (P < .001), and higher incidence of venous thrombosis in PV (P = .01). Younger patients were also more likely to express CALR mutations, in ET and PMF, normal karyotype, in PV and PMF, and lower incidence of high molecular risk mutations in PMF (P significant in all instances). Over median follow-up of 11.3, 13, and 7.1 years for PV, ET, and PMF, leukemic transformations were respectively documented in 4%, 2%, and 10% (P values 0.1-0.9) while incidences of fibrotic progression in PV (22%) and ET (16%) were expectedly higher in young patients, because of their longer survival (P < .001). Median survival in young patients was 37 years for PV, 35 for ET and 20 for PMF; the corresponding values were 22, 22, and 8 years for ages 41-60 years and 10, 11, and 3 years for ages >60 years (P < .001). Young MPN patients comprise a unique disease subset defined by an attenuated-risk cytogenetic and mutational backdrop and conspicuously longer survival compared to their older counterparts, which requires assertion during patient counseling.

Heterogeneity in myeloproliferative neoplasms: Causes and consequences

Myeloproliferative neoplasms (MPNs) are haematopoietic stem cell-derived clonal disorders characterised by proliferation of some or all myeloid lineages, depending on the subtype. MPNs are classically categorized into three disease subgroups; essential thrombocythaemia (ET), polycythaemia vera (PV) and primary myelofibrosis (PMF). The majority (>85%) of patients carry a disease-initiating or driver mutation, the most prevalent occurring in the janus kinase 2 gene (JAK2 V617F), followed by calreticulin (CALR) and myeloproliferative leukaemia virus (MPL) genes. Although these diseases are characterised by shared clinical, pathological and molecular features, one of the most challenging aspects of these disorders is the diverse clinical features which occur in each disease type, with marked variability in risks of disease complications and progression to leukaemia. A remarkable aspect of MPN biology is that the JAK2 V617F mutation, often occurring in the absence of additional mutations, generates a spectrum of phenotypes from asymptomatic ET through to aggressive MF, associated with a poor outcome. The mechanisms promoting MPN heterogeneity remain incompletely understood, but contributing factors are broad and include patient characteristics (gender, age, comorbidities and environmental exposures), additional somatic mutations, target disease-initiating cell, bone marrow microenvironment and germline genetic associations. In this review, we will address these in detail and discuss their role in heterogeneity of MPN disease phenotypes. Tailoring patient management according to the multiple different factors that influence disease phenotype may prove to be the most effective approach to modify the natural history of the disease and ultimately improve outcomes for patients.

Patients with post-essential thrombocythemia and post-polycythemia vera differ from patients with primary myelofibrosis

Prognostic scoring systems for primary myelofibrosis (PMF) are not accurate in patients with post-essential thrombocythemia and post-polycythemia vera myelofibrosis (PET-MF; PPV-MF). Given the paucity of data describing the clinical characteristics, disease course and outcomes of these patients, we sought to describe and compare the clinical characteristics and outcomes of 755 patients with PMF, 181 with PPV-MF, and 163 with PET-MF referred to our institution between 1984 and 2013. The median follow-up was 31 months, and 56% (n=616) patients had died. Over an observation period of 3502 person-years, 11% of patients had progression to AML, with similar rates among groups. The proportion of patients with transfusion dependency (higher in PMF), leukocytosis and systemic symptoms (higher in PPV-MF), and thrombocytopenia (higher in PMF, PPV-MF) differed among groups. Median overall survival (OS) was longest in PET-MF patients (73 mo vs 45 mo (PMF) vs 48 mo (PPV-MF), p <0.001). Stratification of OS by DIPSS was only discriminatory in patients with PMF, and it failed to distinguish higher risk patients with PPV/PET-MF. In multivariate analysis, predictors of inferior OS were higher age, anemia, systemic symptoms, thrombocytopenia, and high peripheral blasts in PMF; age, anemia, and systemic symptoms for PPV-MF; and anemia, peripheral blasts and thrombocytopenia in PET-MF. Although the clinical characteristics of PPV/PET-MF patients are not substantially different from those with PMF, their outcomes differ and prognostic scoring systems for PET/PPV-MF should be improved.

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.

The prognostic relevance of serum lactate dehydrogenase and mild bone marrow reticulin fibrosis in essential thrombocythemia

The 2016 World Health Organization (WHO) diagnostic criteria for myeloproliferative neoplasms (MPN) underscore the prognostically-relevant distinction between essential thrombocythemia (ET) and prefibrotic primary myelofibrosis (pre-PMF). In addition, leukocytosis has been identified as an important prognostic marker in otherwise WHO-defined ET. However, controversy remains regarding the objectivity of morphologic criteria in distinguishing ET from pre-PMF and the precise prognostic cutoff values for leukocytosis. Serum lactate dehydrogenase (LDH) level might be a biologically more accurate measure of leukocyte turnover and a more sensitive marker of pre-PMF, in otherwise WHO-defined ET. In the current study of 183 consecutive patients with WHO-defined ET, the presence of grade 1 bone marrow (BM) fibrosis did not affect presenting clinical or laboratory features; in contrast, increased serum LDH at diagnosis was associated with leukocytosis (p = .002), thrombocytosis (p < .001), palpable splenomegaly (p = .03) and higher international prognostic score (IPSET) (p = .002); serum LDH did not correlate with BM fibrosis, JAK2/CALR/MPL or TET2/ASXL1 mutations. In univariate analysis, risk factors for survival included age ≥60 years (p = .002; HR 10.2, 95% CI 2.3-44.6), male sex (p = .02; HR 3.2, 95% CI 1.2-8.2), leukocyte count ≥15 × 10⁹ /L (p = .007; HR 4.7, 95% CI 1.5-14.6), and increased serum LDH (p = .002; HR 3.7, 95% CI 1.5-9.1), but not BM fibrosis (p = .17). In multivariable analysis, age, sex and serum LDH remained significant; serum LDH also remained significant, in the context of IPSET (p = .003) and in patients with leukocytosis (p = .003). We conclude that serum LDH level carries an independent prognostic value for survival in ET and might represent a biologically more accurate surrogate for leukocytosis.

How to Treat Essential Thrombocythemia and Polycythemia Vera

Polycythemia vera and essential thrombocythemia (ET) are chronic myeloproliferative neoplasms associated with thrombotic or hemorrhagic complications, and increased risk of transformation to myelofibrosis and acute myeloid leukemia. The main goal of therapy is aimed at preventing vascular events that are the leading cause of morbidity and mortality in these patients. Accordingly, risk stratification is the basis for deciding when to treat a patient with cytoreductive therapy. The European LeukemiaNet has developed a series of management recommendations for front-line and second-line therapy to provide the optimal treatment for the individual patient. There is still controversy about the efficacy and safety of several modalities of cytoreductive treatment in the long-term for both diseases and in the use of antiplatelet therapy in ET. The presence of JAK2V617F and CALR mutations in patients with ET has been related to different thrombotic risks, and this will probably lead to different therapeutic approaches in the near future. On the other hand, the near normal life expectancy of these patients makes a careful analysis of the benefits and risks associated with treatment essential. This review provides our current management strategy of patients with polycythemia vera and ET.

Impact of JAK2V617F Mutational Status on Phenotypic Features in Essential Thrombocythemia and Primary Myelofibrosis

Objective:

The JAK2V617F mutation is present in the majority of patients with essential thrombocythemia (ET) and primary myelofibrosis (PMF). The impact of this mutation on disease phenotype in ET and PMF is still a matter of discussion. This study aims to determine whether there are differences in clinical presentation and disease outcome between ET and PMF patients with and without the JAK2V617F mutation.

Materials and Methods:

In this single-center study, a total of 184 consecutive Philadelphia-negative chronic myeloproliferative neoplasms, 107 cases of ET and 77 cases of PMF, were genotyped for JAK2V617F mutation using the JAK2 Ipsogen MutaScreen assay, which involves allele-specific polymerase chain reaction.

Results:

ET patients positive for JAK2V617F mutation had higher hemoglobin (Hb) and hematocrit (Hct) levels, lower platelet counts, and more prevalent splenomegaly at diagnosis compared to patients negative for the JAK2V617F mutation, but rates of major thrombotic events, arterial thrombosis, and venous thrombosis were comparable between the groups. At presentation, PMF patients with JAK2V617F mutation had significantly higher Hb and Hct levels and leukocyte counts than patients without the mutation. Similar to the findings of ET patients, thromboembolic rates were similar in PMF patients with and without theJAK2V617F mutation. For ET and PMF patients, no difference was observed in rates of death with respect to JAK2V617F mutational status. Moreover, leukemic transformation rate was not different in our PMF patients with and without JAK2V617F mutation.

Conclusion:

We conclude that JAK2V617F-mutated ET patients express a polycythemia vera-like phenotype and JAK2V617F mutation in PMF patients is associated with a more pronounced myeloproliferative phenotype.

Blast transformation and fibrotic progression in polycythemia vera and essential thrombocythemia: a literature review of incidence and risk factors

Polycythemia vera (PV) and essential thrombocythemia (ET) constitute two of the three BCR-ABL1-negative myeloproliferative neoplasms and are characterized by relatively long median survivals (approximately 14 and 20 years, respectively). Potentially fatal disease complications in PV and ET include disease transformation into myelofibrosis (MF) or acute myeloid leukemia (AML). The range of reported frequencies for post-PV MF were 4.9–6% at 10 years and 6–14% at 15 years and for post-ET MF were 0.8–4.9% at 10 years and 4–11% at 15 years. The corresponding figures for post-PV AML were 2.3–14.4% at 10 years and 5.5–18.7% at 15 years and for post-ET AML were 0.7–3% at 10 years and 2.1–5.3% at 15 years. Risk factors cited for post-PV MF include advanced age, leukocytosis, reticulin fibrosis, splenomegaly and JAK2V617F allele burden and for post-ET MF include advanced age, leukocytosis, anemia, reticulin fibrosis, absence of JAK2V617F, use of anagrelide and presence of ASXL1 mutation. Risk factors for post-PV AML include advanced age, leukocytosis, reticulin fibrosis, splenomegaly, abnormal karyotype, TP53 or RUNX1 mutations as well as use of pipobroman, radiophosphorus (P³²) and busulfan and for post-ET AML include advanced age, leukocytosis, anemia, extreme thrombocytosis, thrombosis, reticulin fibrosis, TP53 or RUNX1 mutations. It is important to note that some of the aforementioned incidence figures and risk factor determinations are probably inaccurate and at times conflicting because of the retrospective nature of studies and the inadvertent labeling, in some studies, of patients with prefibrotic primary MF or ‘masked' PV, as ET. Ultimately, transformation of MPN leads to poor outcomes and management remains challenging. Further understanding of the molecular events leading to disease transformation is being investigated.

Acute ST-segment elevation myocardial infarction as the first manifestation of essential thrombocytosis successfully treated with thrombectomy alone

A patient with no conventional cardiovascular risk factors presented with inferior ST-elevation myocardial infarction which was finally diagnosed as a case of essential thrombocytosis. This case demonstrated that thrombectomy alone was sufficient for the treatment of his coronary occlusion. Furthermore, this case report highlights the importance of evaluating rare causes of myocardial infarction other than atherosclerosis and that internists and cardiologists should be aware of essential thrombocytosis as a known cause of myocardial infarction, particularly in patients with no underlying cardiovascular risk factors.

The impact of JAK2V617F mutation on different types of thrombosis risk in patients with essential thrombocythemia: a meta-analysis

To assess the effect of JAK2V617F on different thrombotic risks in essential thrombocythemia (ET) patients, we identified eligible studies from several databases including Pubmed, Embase, and Cochrane Central Register of Controlled Trials (up to November 2014). Twenty-two studies of 2922 ET patients were included in exploring the relationship between JAK2V617F and the risk of thrombosis. Compared to JAK2V617F-negative ET patients, JAK2V617F-positive ET patients had higher odd risks (ORs) of arterial thrombosis [OR = 2.59 (1.84-3.65)] and venous thrombosis [OR = 2.10 (1.53-2.88)]. The JAK2V617F-positive group was also more prone to increased risk of microcirculatory disturbances [OR = 1.50 (0.97-2.32)]. Moreover, JAK2V617F may indicate increased risk of either arterial [OR = 1.71 (1.22-2.39)] or venous thrombosis [OR = 2.90 (1.54-5.46)] before diagnosis of ET. During follow-up, JAK2V617F might not be related to arterial thrombosis [OR = 1.90 (0.90-2.08)], but rather venous thrombosis [OR = 1.95 (1.08-3.53)]. In conclusion, JAK2V617F increased the risk of arterial and venous thrombosis in ET patients, while understanding its role in microcirculatory disturbances will require further studies.

The importance of cardiovascular risk factors for thrombosis prediction in patients with essential thrombocythemia

The current widely accepted stratification defined by age and previous thrombosis in patients with essential thrombocythemia (ET) probably deserves deeper analysis. The aim of our study was to identify additional factors at the time of diagnosis, which have an impact on the thrombosis prediction. We conducted a study of 244 consecutive ET patients with median follow-up of 83 months. We analyzed the influence of age, gender, laboratory parameters, history of previous thrombosis, spleen size, JAK2 mutation as well as cardiovascular (CV) risk factors including arterial hypertension, diabetes, active tobacco use and hyperlipidemia in the terms of thrombosis. The most important predictors of thrombosis in multivariate Cox regression model were the presence of CV risk factors (p=0.004) and previous thrombosis (p=0.038). Accordingly, we assigned risk scores based on multivariable analysis-derived hazard ratios (HR) to the presence of 1 CV risk factor (HR=3.5; 1 point), >1 CV risk factors (HR=8.3; 2 points) and previous thrombosis (HR=2.0; 1 point). A final three-tiered prognostic model for thrombosis prediction was developed as low (score 0), intermediate (score 1 or 2) and high risk (score 3) (p<0.001). The hazard of thrombosis was 3.8% in low-risk group, 16.7% in the intermediate-risk group and 60% in the high-risk group (p<0.001). Patients with thrombotic complications during the follow-up had a significantly shorter survival (p=0.018). The new score based on CV risk factors and previous thrombotic events allows a better patient selection within prognostic-risk groups and improved identification of the high-risk patients for thrombosis.

[Essential thrombocythemia: baseline characteristics and risk factors for survival and thrombosis in a series of 214 patients]

BACKGROUND AND OBJECTIVE

Two prognostic models to predict overall survival and thrombosis-free survival have been proposed: International Prognostic Score for Essential Thrombocythemia (IPSET) and IPSET-Thrombosis, respectively, based on age, leukocytes count, history of previous thrombosis, the presence of cardiovascular risk factors and the JAK2 mutational status. The aim of the present study was to assess the clinical and biological characteristics at diagnosis and during evolution in essential thrombocythemia (ET) patients as well as the factors associated with survival and thrombosis and the usefulness of these new prognostic models.

PATIENTS AND METHODS

We have evaluated the clinical data and the mutation status of JAK2, MPL and calreticulin of 214 ET patients diagnosed in a single center between 1985 and 2012, classified according to classical risk stratification, IPSET and IPSET-Thrombosis.

RESULTS

With a median follow-up of 6.9 years, overall survival was not associated with any variable by multivariate analysis. Thrombotic history and leukocytes>10×10(9)/l were associated with thrombosis-free survival (TFS). In our series, IPSET prognostic systems of survival and thrombosis did not provide more clinically relevant information regarding the classic risk of thrombosis stratification.

CONCLUSION

Thrombotic history and leukocytosis>10×10(9)/l were significantly associated with lower TFS, while the prognostic IPSET-Thrombosis system did not provide more information than classical thrombotic risk assessment.

Surgical treatment of a ventricular aneurysm in a patient with essential thrombocythemia complicated by acute myocardial infarction: A case report

Essential thrombocythemia (ET) is a chronic clonal myeloproliferative disorder, which is often complicated by arterial or venous thrombosis and idiopathic bleeding diathesis. The present study reports a female patient with ET complicated by acute myocardial infarction, leading to ventricular aneurysm following interventional therapy for 3 years and a subsequent in-stent restenosis. Following careful examination, a ventricular aneurysm resection and coronary artery bypass graft were carried out. During this case, the monitoring and controlling of the platelet count, pre- and post-operatively, was extremely important for successful surgery.

Paediatric essential thrombocythaemia: clinical and molecular features, diagnosis and treatment

The incidence of essential thrombocythaemia (ET) in children (age ≤18 years) is extremely low. The natural course of the disorder in children has not been clarified. The rarity of patients and the variability of tested parameters make it difficult to draw any definitive conclusion in pathogenesis and diagnosis of paediatric ET. What makes the onset of thrombocytosis earlier in children is still uncertain. A diagnostic algorithm for paediatric ET has not been established, and current risk stratification used to guide therapeutic decisions in adults has not been validated in children. Vascular complications and transformation to myelofibrosis and leukaemia in this special entity have been reported, suggesting that ET in children is not an entirely benign disease. The crucial question is how to identify patients who are at high risk of complications and need treatment. There are insufficient data to recommend a specific agent in children. The purpose of this review is to outline the most recent progress in paediatric ET and to help with understanding the clinical course, molecular features, diagnosis and treatment strategies in this special group.

PVSG and WHO vs European Clinical, Molecular and Pathological Criteria for prefibrotic myeloproliferative neoplasms

The Polycythemia Vera Study Group (PVSG), World Health Organization (WHO) and European Clinical, Molecular and Pathological (ECMP) classifications agree upon the diagnostic criteria for polycythemia vera (PV) and advanced primary myelofibrosis (MF). Essential thrombocythemia (ET) according to PVSG and 2007/2008 WHO criteria comprises three variants of JAK2^V617F mutated ET when the ECMP criteria are applied. These include normocellular ET, hypercellular ET with features of early PV (prodromal PV), and hypercellular ET due to megakaryocytic, granulocytic myeloproliferation (ET.MGM). Evolution of prodromal PV into overt PV is common. Development of MF is rare in normocellular ET (WHO-ET) but rather common in hypercellular ET.MGM. The JAK2^V617F mutation burden in heterozygous mutated normocellular ET and in heterozygous/homozygous or homozygous mutated PV and ET.MGM is of major prognostic significance. JAK2/MPL wild type ET associated with prefibrotic primary megakaryocytic and granulocytic myeloproliferation (PMGM) is characterized by densely clustered immature dysmorphic megakaryocytes with bulky (bulbous) hyperchromatic nuclei, which are never seen in JAK2^V617F mutated ET, and PV and also not in MPL⁵¹⁵ mutated normocellular ET (WHO-ET). JAK2^V617 mutation burden, spleen size, LDH, circulating CD34⁺ cells, and pre-treatment bone marrow histopathology are mandatory to stage the myeloproliferative neoplasms ET, PV, PMGM for proper prognosis assessment and therapeutic implications. MF itself is not a disease because reticulin fibrosis and reticulin/collagen fibrosis are secondary responses of activated polyclonal fibroblasts to cytokines released from the clonal myeloproliferative granulocytic and megakaryocytic progenitor cells in ET.MGM, PV and PMGM.

Thrombotic complications of myeloproliferative neoplasms: risk assessment and risk-guided management

Philadelphia-negative myeloproliferative neoplasms are considered to be acquired thrombophilic states. Thromboses, both arterial and venous (not rarely in unusual sites), are often the initial events leading to the diagnosis. After diagnosis, the yearly incidence of thrombotic events is highly variable, and ranges from approximately 1% to 10%. The identification of patients at risk who may benefit from antithrombotic therapy remains a challenge, and it is currently based on age and history of thrombotic events. However, the predictive value of these clinical characteristics is rather limited. Few prospective studies and even fewer interventional randomized studies are available, and there are no studies designed to formally validate the use of risk stratification. The implementation of laboratory parameters such as leukocytosis and/or the JAK2 V617F mutation into a scoring system may be of interest. The mechanisms at work leading to thrombosis remain largely speculative, but are likely to be complex and multifactorial, with a prominent role of cell-cell interactions, mostly owing to qualitative changes. The long-term treatment options to prevent thrombosis are, schematically, aspirin alone as primary prevention for the low-risk patients, and cytoreduction combined with aspirin for the other patients. In very low-risk young essential thrombocythemia patients, abstention can even be considered. The optimal duration of anticoagulation after a thrombotic event is not established. All antithrombotic therapies should be balanced with the hemorrhagic risk, which can also be increased in these patients.

Ruxolitinib for myelofibrosis

The aim of the present study was to assess the beneficial and harmful effects of ruxolitinib in patients with myelofibrosis (MF). The Cochrane databases, PubMed and Embase were searched for studies published up to October 2012. Randomised controlled trials assessing ruxolitinib versus a placebo or the best available therapy in patients with MF were included. Two trials randomised 528 patients with MF to ruxolitinib versus a placebo or ruxolitinib versus the best available therapy. Compared with the placebo, ruxolitinib had a significant beneficial effect on the proportion of patients that had a reduction in spleen volume of ≥35% at 24 weeks [odds ratio (OR), 109.78; 95% confidence interval (CI), 14.97–804.78] or an increased overall survival rate (OR, 2.02; 95% CI, 0.99–4.12). Ruxolitinib significantly increased the risk of several non-haematological or haematological adverse events, but not the risk of treatment discontinuations (OR, 1.04; 95% CI, 0.50–2.14). Compared with the best available therapy, ruxolitinib had a significant beneficial effect on the proportion of patients that had a reduction in spleen volume of ≥35% at 24 (OR, 68.45; 95% CI, 4.15–1129.19) or 48 weeks (OR, 56.20; 95%CI, 3.40–928.67). Ruxolitinib once again significantly increased the risk of several non-haematological adverse events, serious adverse events and dose reductions or interruptions (OR, 9.60; 95% CI, 4.66–19.81), but not the risk of treatment discontinuations (OR, 1.54; 95% CI, 0.48–4.97). In conclusion, based on the trials included in the present study, the use of ruxolitinib is beneficial in the treatment of MF.