How I treat essential thrombocythemia

Imetelstat in myeloid malignancies: current data and future directions

INTRODUCTION

Telomerase reactivation allows cancer cells to maintain telomere length and evade senescence, making it an appealing therapeutic target. Imetelstat, an antisense oligonucleotide, is the first clinically effective telomerase inhibitor approved by the FDA and the European Commission for treating anemia in transfusion-dependent low-risk myelodysplastic syndromes (MDS).

AREAS COVERED

Sources for this review were identified through searches of PubMed, ClinicalTrials.gov, and conference abstracts. This review highlights the pharmacology, efficacy, and ongoing trials of imetelstat in treating MDS, myelofibrosis, essential thrombocythemia, and other malignancies. In the IMerge trial, imetelstat induced durable transfusion independence in heavily transfused LR-MDS patients. Pilot trials in myelofibrosis suggest imetelstat's potential disease-modifying properties and survival benefit, warranting further studies of imetelstat as a monotherapy or in combination therapies. Imetelstat can cause thrombocytopenia, leukopenia, elevated liver enzymes, and infusion reactions, which are mostly reversible but may rarely lead to fatal events.

EXPERT OPINION

Future clinical trials in LR-MDS should focus on optimal sequencing and combination strategies for imetelstat with other agents, and identifying biomarkers that can predict response. Monitoring real-world outcomes will offer valuable insights into imetelstat's safety and efficacy in patient populations underrepresented in clinical trials. Imetelstat's role in other malignancies, especially myelofibrosis, is being explored.

Relationship between additional mutations at diagnosis and treatment response in patients with essential thrombocythemia

ABSTRACT

Patients with essential thrombocythemia (ET) have a chronic evolution with a risk of hematologic transformation associated with a dismal outcome. Because patients with resistance or intolerance have adverse prognosis, it is important to identify which patient will respond to first-line treatment. We, therefore, aim to describe the association between additional mutations and response to first-line treatment in patients with ET. In this retrospective study, we analyzed the molecular landscape of 121 ET patients first-line treated with hydroxyurea (HU; n = 86) or pegylated interferon (peg-IFN; n = 35). Patients undergoing peg-IFN therapy were younger and had higher proportion of low and very low risk of thrombosis recurrence. A total of 62 patients (51%) had ≥1 additional mutations at diagnosis. At 12 months of treatment, 75 patients (62%) achieved complete response (CR), 37 (31%) partial response, and 7 (6%) no response. The presence of at least 1 additional mutation at diagnosis was associated with not achieving CR (hazard ratio [HR], 0.65; P = .038), whereas treatment with peg-IFN was associated with higher CR (HR, 2.00; P = .002). The number of additional mutations at diagnosis was associated with hematologic progressions (P < .0001). None of the patients receiving peg-IFN therapy progressed to myelofibrosis, whereas 16 of 86 patients (19%) treated with HU developed secondary myelofibrosis. In conclusion, our results suggest that the presence of at least 1 additional mutation at diagnosis is associated with failure to achieve CR and also with an increased risk of hematologic evolution.

Proinflammatory and prothrombotic conditions in JAK2V617F-positive MPN: a case of Lemierre's syndrome in essential thrombocythemia

Lemierre's syndrome (LS) represents a rare yet potentially life-threatening systemic infection, characterized by thrombophlebitis of the internal jugular vein and abscess formation in distant organs. It typically follows episodes of tonsillitis or other infections of the oropharyngeal region. Pulmonary complications, including septic pulmonary emboli, are common. Essential thrombocythemia (ET) is a chronic myeloproliferative neoplasm (MPN) sometimes associated with the JAK2V617F mutation, which predisposes patients to thrombotic events. A 66-year-old male with JAK2V617F-positive ET presented with severe pulsatile pain radiating from the right temporal region to the occipital area following a recent dental infection. Although pain management was administered, the pain continued to persist. Computed tomography of the chest revealed multiple subpleural nodules, raising suspicion for septic pulmonary emboli. Further investigation with gadolinium-enhanced magnetic resonance imaging identified a thrombus extending from the right sigmoid sinus into the internal jugular vein, consistent with cerebral venous thrombosis. The patient was diagnosed with　LS, complicated by septic thrombosis. Blood cultures yielded alpha-hemolytic streptococcus. Empirical antimicrobial therapy combined with anticoagulation was initiated, resulting in a gradual improvement of symptoms, including the resolution of fever and pain. Follow-up imaging confirmed the resolution of both the infection and thrombosis. This is the first reported case of LS in a patient with JAK2V617F-positive ET. The coexistence of LS and JAK2V617F-positive MPN highlights the potential interplay between proinflammatory and prothrombotic conditions associated with the JAK2V617F mutation.

Impact of Hydroxyurea to Treat Haematological Disorders on Male Fertility: Two Case Reports and a Systematic Review

PURPOSE

Hydroxyurea (HU) is a cytoreductive agent used as standard treatment option for sickle cell anaemia/disease (SCD), essential thrombocythemia (ET), and polycythaemia vera (PV). Despite its overall good safety profile, its use also in relatively young patients raises an interest on its potential impact on spermatogenesis. To perform a systematic review of all published articles investigating fertility in male patients affected by SCD, ET, and PV and treated with HU. Two paradigmatic case reports of patients affected by PV and ET, respectively, have been also reported.

MATERIALS AND METHODS

PubMed, EMBASE, and Cochrane databases were queried for all the published studies indexed up to November 15th, 2022. A combination of the following keywords was used: "hydroxyurea," "fertility," "male," "sperm," "sickle cell anaemia," "sickle cell disease," "essential thrombocythemia," "polycythaemia vera."

RESULTS

Of 48 articles identified, 8 studies, involving 161 patients, were eligible for inclusion. Overall, the number of spermatogonia per round cross section of seminiferous tubule were decreased in patients with SCD compared to healthy males. HU treatment was always associated with a worsening of semen parameters, even up to azoospermia. Notably, treatment discontinuation was associated with an improvement of semen parameters and a trend toward normalization in the case of PV and ET, with a less clear amelioration in men with SCD. In both our patients with either PV or ET, HU discontinuation was associated with a significant improvement of spermatogenesis with successful spontaneous pregnancies.

CONCLUSIONS

Published evidence do not consistently report normalization of spermatogenesis after HU discontinuation in SCD cases. Conversely, the literature almost consistently reported an improvement of semen parameters at the discontinuation of HU therapy in PV and ET cases. Our real-life two cases confirmed those findings. The willing of fatherhood and the need for effective fertility treatment warrant further research to improve work-up management in men with hematological disorders.

Understanding triple negative myeloproliferative neoplasms: pathogenesis, clinical features, and management

ABSTRACTMyeloproliferative neoplasms (MPNs) that lack the classical "driver mutations," termed triple negative MPNs, remain a poorly understood entity. Despite considerable progress toward understanding MPN pathobiology, the mechanisms leading to the development of these MPNs remains inadequately elucidated. While triple negative primary myelofibrosis (TN-PMF) portends a poor prognosis, triple negative essential thrombocythemia (TN-ET) is more favorable as compared with JAK2 mutated ET. In this review, we summarize the clinical features and prognosis of TN-PMF and -ET as well as diagnostic challenges including identification of non-canonical driver mutations. We also discuss additional molecular drivers to better understand possible pathogenic mechanisms underlying triple negative MPNs. Finally, we highlight current therapeutic approaches as well as novel targets, particularly in the difficult to treat TN-PMF population.

Current therapies for classic myeloproliferative neoplasms: A focus on pathophysiology and supportive care

PURPOSE

This article concisely evaluates current therapies that have received regulatory approval for the treatment of classic myeloproliferative neoplasms (MPNs). Pertinent pathophysiology and supportive care are discussed. Emerging therapies are also briefly described.

SUMMARY

MPNs are a heterogeneous group of diseases characterized by acquired abnormalities of hematopoietic stem cells (HSCs), resulting in the generation of transformed myeloid progenitor cells that overproduce mature and immature cells within the myeloid lineage. Mutations in JAK2 and other driver oncogenes are central to the genetic variability of these diseases. Cytoreductive therapies such as hydroxyurea, anagrelide, interferon, and therapeutic phlebotomy aim to lower the risk of thrombotic events without exposing patients to an increased risk of leukemic transformation. However, no comparisons can be made between these therapies, as reduction of thrombotic risk has not been used as an endpoint. On the other hand, Janus kinase (JAK) inhibitors such as ruxolitinib, fedratinib, pacritinib, and momelotinib (an investigational agent at the time of writing) directly target the constitutively activated JAK-signal transducer and activator of transcription (JAK-STAT) pathway of HSCs in the bone marrow. Mutations of genes in the JAK-STAT signaling pathway provide a unifying understanding of MPNs, spur therapeutic innovations, and represent opportunities for pharmacists to optimize mitigation strategies for both disease-related and treatment-related adverse effects.

CONCLUSION

Treatment options for MPNs span a wide range of disease mechanisms. The growth of targeted therapies holds promise for expanding the treatment arsenal for these rare, yet complex diseases and creates opportunities to optimize supportive care for affected patients.

Essential Thrombocythemia in Adolescents and Young Adults: Clinical Aspects, Treatment Options and Unmet Medical Needs

OPINION STATEMENT

Current treatment of essential thrombocythemia (ET) should primarily prevent thrombo-hemorrhagic events, without increasing the rate of fibrotic progression or leukemic evolution, and secondarily control microvascular symptoms. Unlike other classic BCR::ABL1-negative myeloproliferative neoplasms, ET is frequently diagnosed in adolescents and young adults (AYA), defined as individuals aged 15 to 39 years, in up to 20% of patients. However, since the current risk stratification of this disease is based on models, including that of ELN, IPSET-Thrombosis and its revised version, mainly applied to an older patients' population, international guidelines are needed that specifically consider how to evaluate the prognosis of AYAs with ET. Furthermore, although ET is the most frequent MPN among AYA subjects, there is a lack of specific recommendations on how to treat it in this subgroup of patients, as management decisions are typically extrapolated from those for the elderly. Accordingly, since AYAs with ET represent a unique disease subset defined by attenuated genetic risk, more indolent phenotype, and longer survival than their older counterparts, treatment selection requires special attention to specific issues such as the risk of fibrotic/leukemic transformation, carcinogenicity, and fertility. This review article will provide a comprehensive overview of the diagnosis, prognostic stratification, and possible therapeutic approaches for AYA patients with ET, including antiplatelets/anticoagulants and cytoreductive agents, with a focus on pregnancy management in real-life clinical practice.

Risk of thrombosis in essential thrombocythemia according to three prediction models: an external validation study

BACKGROUND

Thrombosis is a major complication of essential thrombocythemia (ET). There are three well-known prediction models for thrombotic risk in ET patients. However, only few external validation studies for the performance of these models in Asian populations have been conducted. Thus, we aimed to evaluate the performance of these models for predicting the risk of thrombosis in Thai patients with ET.

METHODS

We retrospectively evaluated the clinical characteristics and thrombotic risk of 149 Thai ET patients in a university hospital in Southern Thailand between 2002 and 2019. Thrombotic risk variables were evaluated using Cox proportional hazard regression. The Brier score, calibration plot, and Harrel concordance index (C-index) were used to evaluate the performance of the three models.

RESULTS

With a median follow-up of 5.2 years, there were a total of 28 thrombotic events in 26 patients. Age > 60 years was a significant prognostic factor for thrombosis in the multivariate Cox regression analysis. The Brier scores were 0.251, 0.273, and 0.276 in the conventional, IPSET-thrombosis, and revised IPSET-thrombosis models, respectively. The conventional model had optimal calibration and good discrimination (C-index, 0.67; 95%CI:0.55-0.79). The IPSET thrombosis (C-index 0.33; 95%CI:0.20-0.49) and revised IPSET thrombosis (C-index 0.31; 95%CI:0.18-0.44) models showed poor discrimination.

CONCLUSION

The conventional model, which is based on age and history of thrombosis, is the best model to predict thrombotic risk in Thai ET patients. Further studies with a larger number of patients with thrombotic events are needed to validate the IPSET-thrombosis and revised IPSET-thrombosis models.

Von Willebrand factor activity levels are influenced by driver mutation status in polycythemia vera and essential thrombocythemia patients with well-controlled platelet counts

Von Willebrand factor ristocetin cofactor (VWF activity) and platelet count (PLT) are negatively correlated in patients with polycythemia vera (PV) and essential thrombocythemia (ET). However, VWF activity does not always normalize upon controlling PLT in those patients. To address this issue, we investigated the correlation between VWF activity and PLT in PV and ET patients. The negative correlation between VWF activity and PLT was stronger in calreticulin mutation-positive (CALR+) ET than in Janus kinase 2 mutation-positive (JAK2+) PV or ET groups. When PLT were maintained at a certain level (<600 × 10⁹ /L), low VWF activity (<50%) was more frequently observed in JAK2+ PV patients than in JAK2+ ET (p=0.013) or CALR+ ET (p=0.013) groups, and in PV and ET patients with ≥50% JAK2+ allele burden than in those with allele burden <50% (p=0.015). High VWF activity (>150%) was more frequent in the JAK2+ ET group than in the CALR+ ET group (p=0.005), and often associated with vasomotor symptoms (p=0.002). This study suggests that some patients with JAK2+ PV or ET have VWF activity outside the standard range even with well-controlled PLT, and that the measurement of VWF activity is useful for assessing the risk of thrombosis and hemorrhage.

Surgical Complications in Myeloproliferative Neoplasm Patient with Essential Thrombocythemia: A Case Report

Introduction

Essential thrombocythemia (ET) is a myeloproliferative neoplasm (MPN) which could complicate surgical procedures due to thrombosis and spontaneous bleeding. However, currently, there is neither concrete guideline nor prerequisite for ET patients who underwent operations.

Case Report

A 48 year-old-female was admitted to the emergency unit on 21 February 2020 due to vomiting and inability to pass gas/stool. The patient previously had an operation for uterine myoma two weeks before which showed thrombocyte count of 688,000/mm³. The patient was previously diagnosed with essential thrombocythemia with positive JAK2V617 point mutation on 24 June 2019. Laboratory examination showed thrombocyte 1,134,000/mm³ and leukocyte 22,700/mm³ suggestive of neutrophilia. CT scan showed fluid collection with blood density in the abdomen and pelvis. She was then diagnosed with obstructive ileus due to abdominal abscess and intestine adhesion. Adhesiolysis by laparoscopy was performed on 29 February 2020 with thrombocyte count of 727,000/mm³. Patient was able to pass flatus and defecate three days post-surgery. However, a decrease of hemoglobin to 8.2 g/dL on 3 March 2020 with thrombocyte count of 700,000/mm³ was suggestive of internal bleeding. She was discharged three weeks post-surgery after improvement of clinical condition with thrombocyte count of 850,000/mm³. She was given hydroxyurea 1000 mg once every two days, aspirin 80 mg OD, anagrelide 1 mg OD, and amlodipine 10 mg OD.

Conclusion

Myeloproliferative disease patients with high thrombocyte count are subjected to increased risk of thrombotic complications in perioperative settings, thus perioperative management and risk assessment are important to improve quality of life and prevent complications. Surgery in MPN patients with elevated thrombocytes may be considered if the benefits outweigh the risks. More studies in this field should be conducted in-order to provide more data for a guideline or systematic review/meta-analyses.

Patients with myeloproliferative neoplasms and COVID-19 have increased rates of arterial thrombosis

Background

Both coronavirus disease-2019 (COVID-19) and myeloproliferative neoplasms (MPNs) are associated with systemic inflammation and risk of thrombosis. Risk of thrombosis in patients with COVID with and without MPNs has not been extensively studied.

Methods

Retrospective cohort study of 44 patients with MPNs and 1114 patients without MPNs positive for SARS-COV-2. Outcomes were arterial thrombosis (AT), venous thromboembolism (VTE), bleeding, and death. Time-to-event analysis was performed using competing risk regression model and Cox proportional hazards.

Results

AT occurred more frequently in patients with MPN (7% vs. 1%, p = 0.03). Rates of VTE (7% vs. 5%, p = 0.73), bleeding (7% vs. 2%, p = 0.06), and death (9% vs. 6%, p = 0.32) were similar. MPN patients were older and had more cardiovascular comorbidities. After time-to-event competing-risk regression adjusting for age, MPN patients had higher risk of AT (subdivision hazards ratio 3.95, 95% CI 1.09-14.39) but not VTE, bleeding, or death.

Conclusions

Among patients with COVID-19, MPN patients had higher risk of arterial thrombosis but not VTE, bleeding, and death compared with non-MPN patients. Larger studies are needed to confirm our findings given the limited sample size.

Platelet Heterogeneity in Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPNs) are a group of malignant disorders of the bone marrow where a dysregulated balance between proliferation and differentiation gives rise to abnormal numbers of mature blood cells. MPNs encompass a spectrum of disease entities with progressively more severe clinical features, including complications with thrombosis and hemostasis and an increased propensity for transformation to acute myeloid leukemia. There is an unmet clinical need for markers of disease progression. Our understanding of the precise mechanisms that influence pathogenesis and disease progression has been limited by access to disease-specific cells as biosources. Here, we review the landscape of MPN pathology and present blood platelets as potential candidates for disease-specific understanding. We conclude with our recent work discovering progressive platelet heterogeneity by subtype in a large clinical cohort of patients with MPN.

Clinical outcomes of interferon therapy for polycythemia vera and essential thrombocythemia: a systematic review and meta-analysis

Interferon therapy has been used in clinical practice for more than three decades to treat polycythemia vera (PV) and essential thrombocythemia (ET). However, there has been no systematic investigation of its expected outcomes and potential risks. We performed a systematic review and single-arm meta-analysis to assess the clinical outcomes (hematological response, molecular response, vascular events, hematological transformation, and adverse events) after interferon therapy for patients with PV and ET. A systematic search identified 37 reports, including data from 1794 patients that were published before March 2021. The pooled overall hematological response (OHR) rate was 86%, with better OHR rates observed in studies using long-acting interferon (p < 0.001) and studies with younger patients (p = 0.038). The pooled overall molecular response rate was 48%, and inter-study heterogeneity was also related to patient age (p = 0.009). The overall incidence was 0.42/100 person-years for thrombosis, 0.01/100 person-years for hemorrhage, 0.21/100 person-years for myelofibrotic transformation, and 0.08/100 person-years for leukemic transformation. Compared with hydroxyurea, interferon produced a non-inferior hematological response and a superior molecular response. In conclusion, interferon therapy provided high rates of hematological and molecular response for patients with PV and ET and was associated with a favorable prognosis.

Emerging agents and regimens for polycythemia vera and essential thrombocythemia

Polycythemia vera (PV) and essential thrombocythemia (ET) are both driven by JAK-STAT pathway activation and consequently much of the recent research efforts to improve the management and outcomes of patients with these neoplasms have centered around inhibition of this pathway. In addition to newer JAK inhibitors and improved interferons, promising novel agents exploiting a growing understanding of PV and ET pathogenesis and disease evolution mechanisms are being developed. These agents may modify the disease course in addition to cytoreduction. Histone deacetylase, MDM2 and telomerase inhibitors in patients with PV/ET have demonstrated clinically efficacy and serve as chief examples. Hepcidin mimetics, limiting iron availability to red blood cell precursors, offer an exciting alternative to therapeutic phlebotomy and have the potential to revolutionize management for patients with PV. Many of these newer agents are found to improve hematologic parameters and symptom burden, but their role in thrombotic risk reduction and disease progression control is currently unknown. The results of larger, randomized studies to confirm the early efficacy signals observed in phase 1/2 trials are eagerly awaited.

Disease modifying agents of myeloproliferative neoplasms: a review

The identification of driver mutations in Janus kinase (JAK) 2, calreticulin (CALR), and myeloproliferative leukemia (MPL) has contributed to a better understanding of disease pathogenesis by highlighting the importance of JAK signal transducer and activator of transcription (STAT) signaling in classical myeloproliferative neoplasms (MPNs). This has led to the therapeutic use of novel targeted treatments, such as JAK2 inhibitors. More recently, with the development of next-generation sequencing, additional somatic mutations, which are not restricted to MPNs, have been elucidated. Treatment decisions for MPN patients are influenced by the MPN subtype, symptom burden, and risk classification. Although prevention of vascular events is the main objective of therapy for essential thrombocythemia (ET) and polycythemia vera (PV) patients, disease-modifying drugs are needed to eradicate clonal hematopoiesis and prevent progression to more aggressive myeloid neoplasms. JAK inhibitors are a valuable therapeutic strategy for patients with myelofibrosis (MF) who have splenomegaly and/or disease-related symptoms, but intolerance, refractory, resistance, and disease progression still present challenges. Currently, allogeneic stem cell transplantation remains the only curative treatment for MF, but it is typically limited by age-related comorbidities and high treatment-related mortality. Therefore, a better understanding of the molecular pathogenesis and potential new therapies with the aim of modifying the natural history of the disease is important. In this article, I review the current understanding of the molecular basis of MPNs and clinical studies on potential disease-modifying agents.

Tetherin/BST2, a physiologically and therapeutically relevant regulator of platelet receptor signalling

The reactivity of platelets, which play a key role in the pathogenesis of atherothrombosis, is tightly regulated. The integral membrane protein tetherin/bone marrow stromal antigen-2 (BST-2) regulates membrane organization, altering both lipid and protein distribution within the plasma membrane. Because membrane microdomains have an established role in platelet receptor biology, we sought to characterize the physiological relevance of tetherin/BST-2 in those cells. To characterize the potential importance of tetherin/BST-2 to platelet function, we used tetherin/BST-2-/- murine platelets. In the mice, we found enhanced function and signaling downstream of a subset of membrane microdomain-expressing receptors, including the P2Y12, TP thromboxane, thrombin, and GPVI receptors. Preliminary studies in humans have revealed that treatment with interferon-α (IFN-α), which upregulates platelet tetherin/BST-2 expression, also reduces adenosine diphosphate-stimulated platelet receptor function and reactivity. A more comprehensive understanding of how tetherin/BST-2 negatively regulates receptor function was provided in cell line experiments, where we focused on the therapeutically relevant P2Y12 receptor (P2Y12R). Tetherin/BST-2 expression reduced both P2Y12R activation and trafficking, which was accompanied by reduced receptor lateral mobility specifically within membrane microdomains. In fluorescence lifetime imaging-Förster resonance energy transfer (FLIM-FRET)-based experiments, agonist stimulation reduced basal association between P2Y12R and tetherin/BST-2. Notably, the glycosylphosphatidylinositol (GPI) anchor of tetherin/BST-2 was required for both receptor interaction and observed functional effects. In summary, we established, for the first time, a fundamental role of the ubiquitously expressed protein tetherin/BST-2 in negatively regulating membrane microdomain-expressed platelet receptor function.

Exosomes and Extracellular Vesicles in Myeloid Neoplasia: The Multiple and Complex Roles Played by These "Magic Bullets"

Simple Summary

Extracellular vesicles (EVs) are released by the majority of cell types and can be isolated from both cell cultures and body fluids. They are involved in cell-to-cell communication and may shuttle different messages (RNA, DNA, and proteins). These messages are known to influence the microenvironment of cells and their behavior. In recent years, some evidence about the involvement of EVs and exosomes, an EV subgroup, in immunomodulation, the transfer of disease markers, and the treatment of myeloid malignancies have been reported. Little is known about these vesicles in this particular setting of hematologic neoplasia; here, we summarize and critically review the available results, aiming to encourage further investigations.

Abstract

Extracellular vesicles (exosomes, in particular) are essential in multicellular organisms because they mediate cell-to-cell communication via the transfer of secreted molecules. They are able to shuttle different cargo, from nucleic acids to proteins. The role of exosomes has been widely investigated in solid tumors, which gave us surprising results about their potential involvement in pathogenesis and created an opening for liquid biopsies. Less is known about exosomes in oncohematology, particularly concerning the malignancies deriving from myeloid lineage. In this review, we aim to present an overview of immunomodulation and the microenvironment alteration mediated by exosomes released by malicious myeloid cells. Afterwards, we review the studies reporting the use of exosomes as disease biomarkers and their influence in response to treatment, together with the recent experiences that have focused on the use of exosomes as therapeutic tools. The further development of new technologies and the increased knowledge of biological (exosomes) and clinical (myeloid neoplasia) aspects are expected to change the future approaches to these malignancies.

The Essential Thrombocythemia in 2020: What We Know and Where We Still Have to Dig Deep

The Essential Thrombocythemia is a Chronic Philadelphia-negative Myeloproliferative Neoplasm characterized by a survival curve that is only slightly worse than that of age- and sex-adjusted healthy population. The criteria for diagnosis were reviewed in 2016 by WHO. The incidence varies from 0.2 to 2.5:100 000 people per year, with a prevalence of 38 to 57 cases per 100 000 people. The main characteristics of ET are the marked thrombocytosis and the high frequency of thrombosis. The spectrum of symptoms is quite wide, but fatigue results to be the most frequent. Thrombosis is frequently observed, often occurring before or at the time of diagnosis. The classification of thrombotic risk has undergone several revisions. Recently, the revised-IPSET-t has distinguished 4 risk classes, from very low risk to high risk. Driver mutations seem to influence thrombotic risk and prognosis, while the role of sub-driver mutations still remains uncertain. Antiplatelet therapy is recommended in all patients aged ⩾ 60 years and in those with a positive history of thrombosis or with cardiovascular risk factors, while cytoreductive therapy with hydroxyurea or interferon is reserved for high-risk patients.

Rapid Cytoreduction by Plateletapheresis in the Treatment of Thrombocythemia

The objective of this chapter is to provide a systematic overview of current knowledge regarding therapeutic apheresis—primarily therapeutic plateletapheresis (TP)—and to summarize evidence-based practical approaches related to cytapheresis treatment of “hyperthrombocytosis” or “extreme thrombocytosis” (ETC). Our results of platelet (Plt) quantitative/qualitative analyses and evaluation of efficacy of apheresis systems/devices—on the basis of Plt removal and in vivo Plt depletion—will be presented. Our preclinical researches confirmed that in Plt concentrates, the initial ratio of discoid shapes was 70%, spherical 20%, and less valuable (dendritic/balloonized) shapes 10%—with morphological score of platelets (MSP = 300–400). After storage, the ratio of discoid and spherical shapes was decreased, while the less valuable ones progressively increased (MSP = 200). Electron microscopy has shown discoid shapes with typical ultrastructural properties. Spherical shapes with reduced electron density and peripheral location of granules/organelles were detected. Also, dendritic shapes with cytoskeletal “rearrangement,” membrane system integrity damages, and pseudopodia formations were documented. Our clinical study demonstrated that TP was useful in ETC treatment and should help prevention of “thrombo-hemorrhagic” events—until chemotherapy, antiplatelet drugs, and other medication take effect. During TP treatment, Plt count and morphology/ultrastructure were examined. Plt functions by multiplate analyzer were evaluated. We concluded that intensive TP was an effective, safe, and rapid cytoreductive treatment for ET.

Essential Thrombocythemia in a Nonagenarian Presenting With Acute Myocardial Infarction

Essential thrombocythemia (ET) is a chronic Philadelphia-negative myeloproliferative neoplasm (MPN) characterized by clonal thrombocytosis and an increased risk of arterial and venous thrombosis. Because ET has a low probability of progressing to acute leukemia or myelofibrosis and its prognosis is determined by thromboembolic or bleeding symptoms, the treatment of this disease is aimed at preventing vascular events. We encountered a nonagenarian patient with ET who presented with acute myocardial infarction with ST-segment elevation. In the present case, the patient was 91 years old, and antithrombotic agents were required after the placement of drug-eluting stent. Therefore, we decided not to perform cytoreductive therapy because the risk of bleeding is higher. Very elderly patients with ET are at an increased risk of thrombotic and hemorrhagic events. The risk-benefit of antithrombotic therapy should be considered individually.

Patients with Essential Thrombocythemia may be Poor Responders to Enteric-Coated Aspirin, but not to Plain Aspirin

Essential thrombocythemia (ET) patients are treated with aspirin (acetylsalicylic acid [ASA]) to prevent thrombosis. Previous studies showed that serum thromboxane (Tx) B₂ was high 24 hours after enteric-coated (EC)-ASA in ET patients, due to increased number of noninhibited reticulated platelets (RPs), consequent to high platelet turnover, and that ASA should be given twice a day to ET patients. We studied ET patients (n = 17) and healthy subjects (n = 10) on 100 mg EC-ASA once daily; experiments were repeated after 14-day treatment with 100 mg plain-ASA once daily. Serum TxB₂, plasma ASA, and salicylic acid (SA) were measured before the morning dose and up to 8 hours thereafter. Blood activity of ASA-deacethylating esterases, in vitro inhibition of collagen-induced TxB₂ production by ASA (10-1,000 µM), and number of RP were measured. TxB₂ inhibition by ASA in vitro and esterases activities were normal in all subjects. EC-ASA elicited highly variable responses; 6 ET patients were poor responders, as their serum TxB₂ was high after EC-ASA; their plasma levels of ASA and SA were low/undetectable. In contrast to EC-ASA, plain ASA decreased serum TxB₂ and increased plasma ASA and SA in all subjects. Serum TxB₂ was high in ET patients at 24 hours and significantly correlated with RP count (but not RP percentage) and platelet count. Plain ASA should be used in ET patients to inhibit platelets efficiently. The identification of ET patients who might benefit from twice a day ASA could simply be based on their platelet count: since their platelet turnover is not increased, ET patients with normalized platelet count should not need twice a day ASA treatment.

Anagrelide in Essential Thrombocythemia (ET): Results from 150 patients over 25 years by the "Ph1-negative Myeloproliferative Neoplasms Latium Group"

BACKGROUND AND AIMS

Anagrelide is a drug effective in reducing platelet counts in essential thrombocythemia (ET) and Ph1-negative myeloproliferative neoplasms. The aim of this study was to evaluate the real-life use of anagrelide in patients with ET followed over 25 years at the Haematological Institutes belonging to "Ph1-negative Myeloproliferative Neoplasms Latium Group."

PATIENTS AND METHODS

Eligibility criteria were diagnosis of ET and treatment with anagrelide. Data were collected through an ad hoc case report form.

RESULTS

One hundred and fifty patients received anagrelide for a median time of 7.4 years (0.1-23.2). Anagrelide was administered as first-line therapy in 34.7% of patients, as second-line in 52% and as third-line in 13.3%: 85.4% responded to therapy. Sixty-eight/136 evaluable patients reported side effects: palpitations, peripheral vasodilation, anaemia, diarrhoea and gastric distress. Fourteen thrombotic (arterial 10, venous 4) and 51 bleeding events (minor 48, major 3) occurred. Sixteen/150 (10.6%) patients developed secondary myelofibrosis and 3/150 (2%) an acute myeloid leukaemia.

CONCLUSIONS

In our experience, anagrelide is an effective drug in reducing platelet levels in a high percentage of patients with ET. It is especially addressed to younger people. A careful assessment of the thrombotic risk and monitoring of cardiac function, at diagnosis and during follow-up, is mandatory.

Essential thrombocythemia A retrospective case series

BACKGROUND

Essential thrombocythemia (ET) is rare in children, and pediatric guidelines are lacking. Therefore, we aimed to evaluate ET diagnosis and treatment in a pediatric cohort.

PROCEDURE

Data of patients with ET from three hospitals were reviewed. Molecular diagnosis included JAK2V617F, CALR, and MPL mutations. Patients were evaluated for acquired von Willebrand syndrome (AVWS). Follow-up included clinical symptoms, adverse events, and treatment.

RESULTS

Twelve children (median age: 8 years, range 1-14.5) were included. Mean lag period between the first documentation of thrombocytosis until ET diagnosis was 36 months. Six patients were positive for JAK2V617F and two for CALR mutations. In six of nine patients, AVWS was diagnosed. At diagnosis, only 33% of patients started therapy with aspirin (n = 4) and hydroxyurea (n = 2). In three of eight untreated patients, therapy was added during follow-up. The cohort was followed for a median of 32.5 months (range: 4-108 months). Clinical follow-up disclosed vascular complications in 4 of 12 patients (deep vein thrombosis, n = 1; transient ischemic attack, n = 3). Two females experienced excessive bleeding; both were diagnosed with AVWS. Neither leukemia nor myelofibrosis evolved in our cohort.

CONCLUSION

Increased awareness to pediatric ET is warranted, as delayed diagnosis is common. Compared to adults, AVWS may be more prevalent among children with ET.

Platelet Counting: Ugly Traps and Good Advice. Proposals from the French-Speaking Cellular Hematology Group (GFHC)

Despite the ongoing development of automated hematology analyzers to optimize complete blood count results, platelet count still suffers from pre-analytical or analytical pitfalls, including EDTA-induced pseudothrombocytopenia. Although most of these interferences are widely known, laboratory practices remain highly heterogeneous. In order to harmonize and standardize cellular hematology practices, the French-speaking Cellular Hematology Group (GFHC) wants to focus on interferences that could affect the platelet count and to detail the verification steps with minimal recommendations, taking into account the different technologies employed nowadays. The conclusions of the GFHC presented here met with a "strong professional agreement" and are explained with their rationale to define the course of actions, in case thrombocytopenia or thrombocytosis is detected. They are proposed as minimum recommendations to be used by each specialist in laboratory medicine who remains free to use more restrictive guidelines based on the patient’s condition.

Progress in elucidation of molecular pathophysiology of myeloproliferative neoplasms and its application to therapeutic decisions

Myeloproliferative neoplasms (MPNs) are hematological diseases that are driven by somatic mutations in hematopoietic stem and progenitor cells. These mutations include JAK2, CALR and MPL mutations as the main disease drivers, mutations driving clonal expansion, and mutations that contribute to progression of chronic MPNs to myelodysplasia and acute leukemia. JAK-STAT pathway has played a central role in the disease pathogenesis of MPNs. Mutant JAK2, CALR or MPL constitutively activates JAK-STAT pathway independent of the cytokine regulation. Symptomatic management is the primary goal of MPN therapy in ET and low-risk PV patients. JAK2 inhibitors and interferon-α are the established therapies in MF and high-risk PV patients.

What cardiologists should know about essential thrombocythemia and acute myocardial infarction: report of two cases and advanced heart failure therapies considerations

We present the cases of two young male patients aged 22 and 31 without prior medical history nor cardiovascular risk factors, who presented to the hospital with large anterior ST-elevation myocardial infarction (STEMI). Urgent coronary angiography revealed acute thrombotic occlusion of the proximal left anterior descending artery in both patients. Persistent thrombocytosis was noted and subsequent investigations led to the diagnosis of essential thrombocythemia (ET) with positive JAK2-V617F mutation. Myocardial infarction as a first clinical manifestation of ET is rare but must be considered in patients without cardiovascular risk factors who show persistent thrombocytosis. In young patients without risk factors, there may be great delays before the diagnosis of STEMI is made. Longer time to revascularization of extensive STEMI is associated with adverse outcomes and cardiogenic shock which can lead to advanced therapies like heart transplant and left ventricular assist device (LVAD). Considering the favorable long-term prognosis of patients with ET, advanced therapies may be a valuable option in the presence of severe left ventricular dysfunction.

In-stent Massive Thrombi Formation During Primary Percutaneous Coronary Intervention in a Patient with Acute Myocardial Infarction Complicated with Essential Thrombocythemia

A 61-year-old man with essential thrombocythemia (ET) presented with acute myocardial infarction (AMI) and underwent primary percutaneous coronary intervention. After stent deployment from the left main (LM) to the left anterior descending artery, intravascular ultrasound revealed thrombi formation in the whole stent. Two days later, optical frequency domain imaging confirmed stent malapposition and thrombi remaining in only the LM. The stent malapposition and ET might have contributed to this phenomenon. He underwent an additional stent expansion and aggressive anti-thrombotic regimen. AMI complicated with ET carries increased risks of in-stent thrombi formation and requires careful revascularization and aggressive pharmacotherapy.

Evaluation of platelet function in essential thrombocythemia under different analytical conditions

Background. Studies of platelet aggregation (PA) in essential thrombocythemia (ET) reported contrasting results, likely due to differences in analytical conditions.Objective. We investigated platelet aggregation using different techniques and analytical conditions.Patients and Methods. PA was studied by light-transmission aggregometry (LTA) in platelet-rich plasma (PRP) and impedance aggregometry in PRP and whole blood (WB). ADP, collagen, thrombin receptor activating peptide (TRAP-14) and adrenaline were used as agonists. Since ET patients (n = 41) were on treatment with aspirin (100 mg/d), healthy controls (n = 29) were given aspirin (100 mg/d) for 5 days before testing: therefore, thromboxane A₂-independent PA was tested in all subjects. Blood samples were collected in citrate (C) [low Ca²⁺] or lepirudin (L) [physiological Ca²⁺]; platelet count was adjusted to 250 x 10⁹/L in a set of C-PRP (adjusted C-PRP) and left unmodified in the other samples.Results. Results of PA in 17 ET patients who were poor responders to aspirin (high serum thromboxane B2 levels) were not included in the analysis. With LTA, PA in ET was lower than in controls in adjusted C-PRP and normal in native C-PRP and L-PRP. With impedance aggregometry, PA in L-PRP and L-WB tended to be higher in ET than in controls. Platelet serotonin and ADP contents were reduced in ET. The percentages of circulating platelets expressing P-selectin and platelet-leukocyte hetero-aggregates were higher in ET.Conclusions. Analytical conditions dramatically affect in vitro PA of ET patients, which appears defective under the least physiological conditions and normal/supranormal under conditions that are closer to the physiological.

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.

A Rare Case of Triple-Negative Essential Thrombocythemia in a Young Postsplenectomy Patient: A Diagnostic Challenge

The distinction between primary and reactive thrombocytosis by bone marrow histology is very important. Reactive thrombocytosis, the most common cause of thrombocytosis, can be expected in postsplenectomy states; however, close hematological evaluation of prolonged thrombocytosis is essential to identify patients who may have an underlying myeloproliferative neoplasm. We report a 37-year-old woman who was found to have portal, mesenteric, and splenic vein thrombosis with thrombocytosis, two months after she had a splenectomy for spontaneous splenic rupture. Other reactive conditions and myeloproliferative neoplasms (MPN) were excluded, and subsequently, the diagnosis of triple-negative essential thrombocythemia (ET) was established by bone marrow histology. This case of primary thrombocythemia following splenectomy in a young patient illustrates some of the diagnostic difficulties associated with postsplenectomy thrombocytosis. Continuing reports of anecdotal experiences in managing similar complex scenarios is essential and remains the only reference for clinicians facing these rare conditions.

The course of acquired von Willebrand syndrome during pregnancy among patients with essential thrombocytosis

To investigate the course of acquired type 2A von Willebrand syndrome (AVWS) in relation to patient management and outcomes among pregnant patients with essential thrombocytosis (ET). A review of pregnant women with ET evaluated for AVWS at the beginning of pregnancy and at the third trimester. Eighteen women with 24 pregnancies were included in this study. A history of bleeding was noted in 8 (44%) patients. In 20 (83%) pregnancies AVWS was evident at the initial testing. Following initial testing, antithrombotic therapy was administered in 22 (92%) pregnancies (aspirin, n = 20 and low-molecular-weight heparin, n = 2). In the remaining two pregnancies, VWF:RCo levels were below 30%; thus, aspirin was given only after repeat testing at 14-16 weeks. At third trimester testing, median VWF:RCo levels were significantly higher than at the initial testing (86 vs. 48%, P < 0.001), with no evidence of AVWS in any of the patients. Significant increases were also observed in the VWF:Ag level (127 vs. 84%, P < 0.001), the VWF:RCo/VWF:Ag ratio (0.75 vs. 0.54, P < 0.001) and the FVIII level (103 vs. 68%, P < 0.001); while platelet count (359 vs. 701 × 10⁹/l, P < 0.001) and hemoglobin level (11.6 vs. 13.4 g/dl, P < 0.001) decreased. Neuraxial anesthesia was safely performed in 17 (71%) pregnancies. No significant bleeding events occurred during pregnancy and delivery. AVWS-related abnormalities in women with ET mostly improved during pregnancy, with favorable maternal and fetal outcomes. VWF parameters should be tested at early pregnancy and repeated at the third trimester, to guide pregnancy and delivery management.

Coexistent Breast Cancer and Essential Thrombocythemia: How We Addressed the Therapeutic Challenges

Essential thrombocythemia (ET) occurring with breast cancer is uncommon; the therapeutic approach varies and poses a challenge. A 65-year-old female presented to us after being diagnosed with hormone positive, HER2-negative infiltrating ductal carcinoma. She had a platelet count of 600 thou/cu mm. Her JAK2 mutation was positive. Bone marrow biopsy showed increased megakaryocytes. She was diagnosed with ET in the setting of breast cancer. She underwent breast conservation surgery after which aspirin was resumed. Anticipating thrombocytopenia during chemotherapy and given the absence of data combining hydroxyurea with standard chemotherapy used for breast cancer, we felt it prudent to delay cytoreductive therapy for her ET until after completion of breast cancer treatment. Her average platelet count during chemotherapy was 480 thou/cu mm with the lowest being 377 thou/cu mm. Her platelet count remained at goal between 300 and 350 thou/cu mm after four months of hydroxyurea.

A phase 3b, multicenter, open-label extension study of the long-term safety of anagrelide in Japanese adults with essential thrombocythemia

Cytoreductive therapy is used in high-risk essential thrombocythemia (ET) to reduce risk of thrombohemorrhagic complications. Anagrelide is an orally active, quinazolone-derived platelet-lowering agent approved for first-line treatment of high-risk ET in Japan. Long-term safety and efficacy data were collected from 53 Japanese high-risk ET patients (Study 308); 41 patients who completed Study 308 entered this phase 3b, open-label extension (Study 309; NCT01467661). Reductions in mean platelet counts occurred throughout the study, from 1021.6 × 10⁹/L (at Study 308 baseline) to 675.4 × 10⁹/L at final assessment. At month 48 (since Study 308 enrollment), mean platelet count was 444.5 × 10⁹/L in the 10 patients who completed 4 years of therapy. Overall, platelet counts decreased from 1088.3 × 10⁹/L at Study 308 baseline (n = 33) to 473.5 × 10⁹/L at final assessment (n = 31). Long-term platelet count reductions were maintained without marked changes in mean anagrelide dose. Anagrelide was generally well tolerated, with anemia (54.7%) and headache (49.1%) as the most frequent adverse events. These findings indicate that anagrelide effectively reduces platelet counts in high-risk Japanese ET patients, with titration resulting in a well-tolerated, effective and sustainable dose. In conclusion, these results support anagrelide administration to high-risk Japanese ET patients using individualized dosing strategies defined in instructions previously approved in Europe and the USA.

Antithrombotic therapy for venous thromboembolism in myeloproliferative neoplasms

In myeloproliferative neoplasms (MPNs) the incidence of venous thromboembolism (VTE) is 0.6–1.0 per 100 pt-years, and the rate of recurrence after VTE is 6.0–6.5 per 100 pt-yrs. Vitamin K-antagonists (VKA) reduces the risk of recurrence after VTE at usual sites (i.e., deep venous thrombosis (DVT) of the legs and pulmonary embolism (PE)) by 48–69%, with a rate of recurrent thrombosis per 100 pt-yrs of 3.4–4.7 on VKA and 8.9–9.6 off VKA; VKA discontinuation produces a 2.2-fold increased risk of novel thrombotic events with respect to continuation. However, the rate of both recurrent thrombosis and major bleeding on VKA is higher in MPN patients than in non-MPN patients, and the risk-benefit balance of long-term VKA treatment is challenging. In the absence of strong evidence, the tailored management of MPN-related VTE should operatively consider the risk categories for recurrence and bleed well established in the non-MPN setting. In summary, MPN patients with VTE are candidates for life-long VKA treatment, especially after unprovoked proximal DVT and PE. Aspirin can offer a moderate benefit in those patients who stop anticoagulation. The use of direct oral anticoagulants should be explored aiming to ameliorate the rate of bleeding.

ASXL1 mutations in Chinese patients with essential thrombocythemia

Essential thrombocythemia (ET) is characterized by thrombotic and hemorrhagic events. The association of clinical characteristics of Chinese ET patients and additional sex combs like 1 (ASXL1) mutations in these patients has remained to be elucidated. In the present study, 72 newly diagnosed Chinese ET patients were enrolled to determine ASXL1 mutations. Mutations in ASXL1, Janus kinase (JAK)2, calreticulin (CALR) and myeloproliferative leukemia (MPL) genes were detected using Sanger sequencing, and data were statistically analyzed. The frequencies of ASXL1, JAK2 V617F, CALR and MPL W515 mutations in ET patients were 19.4% (14/72), 29.2% (21/72), 31.9% (23/72) and 0% (0/72), respectively. Of note, 28 ET patients (38.9%) were negative for JAK2, CALR and MPL mutations; these patients were classified as triple-negative (TN). The frequency of ASXL1 mutations in patients with JAK2 V617F, CALR and TN mutations was 23.8% (5/21), 21.7% (5/23) and 14.3% (4/28), respectively. ASXL1-mutant patients exhibited significant propensities for thrombotic events compared with the ASXL1 wild-type (wt) cohort (42.9 vs. 12.1%; P=0.021). In addition, JAK2 V617F-mutant patients had a higher mean age compared with CALR-mutant (64.76 vs. 52.96 years; P=0.008) or TN patients (64.76 vs. 51.14 years; P=0.002). Furthermore, more white blood cells in the peripheral blood (PB) were observed in JAK2 V617F-mutant patients compared with those in TN patients (12.40 vs. 8.20×10⁹/l; P=0.02). In addition, CALR-mutant patients exhibited more platelets (PLT) in PB than JAK2 V617F-mutant patients (787.91 vs. 562.17×10⁹/l; P=0.047). TN patients had a significantly lower incidence of clinical symptoms, including dizziness, palpitation and chest congestion compared with CALR- or JAK2 V617F-mutant patients (14.1 vs. 39.1%; P=0.043 and 14.1 vs. 38.1%; P=0.050). No significant difference in progression-free survival was observed between ASXL1-mutant and ASXL1-wt patients (P=0.590). In conclusion, ASXL1-mutant ET patients are prone to experiencing thrombotic events. There was no significant difference in the occurrence of thrombotic events among CARL-mutant, JAK2 V617F-mutant and TN patients. Furthermore, ASXL1-mutant/TN patients exhibited a higher number of PLT than ASXL1/JAK2 V617F-double mutant patients. Therefore, ASXL1 mutations may be a risk factor for the occurrence of thrombotic events in ET patients.

A rare CALR variant mutation and a review of CALR in essential thrombocythemia

Essential thrombocythemia (ET) is an indolent myeloproliferative neoplasm characterized by megakaryocyte hyperplasia, thrombocytosis, thrombotic and hemorrhagic complications, and potential transformation into myelofibrosis and acute myeloid leukemia. The vast majority of cases are driven by a somatic mutation in JAK2, CALR, or MPL. CALR, a gene that codes for the calcium-binding chaperone calreticulin, is the predominant mutation in patients with non-mutated JAK2 essential thrombocythemia, accounting for 20-25% of the overall somatic mutation frequency in ET. In this brief review of ET, we introduce a rare CALR mutation through a case presentation of a 58-year-old man with diffuse pulmonary emboli in the setting of thrombocytosis. We subsequently characterize the main types of CALR mutations and their value in diagnosis and prognosis of disease course, and lastly discuss the current clinical approach to ET.

Evaluation of vascular events in patients with myeloproliferative syndromes and mutations of either the januskinase-2 or calreticulin gene at the university hospital Krems from 2008 to 2015

Myeloproliferative neoplasms (MPN), classified as polycythemia vera (PV), essential thrombocytosis (ET) and myelofibrosis (MF) are stem-cell derived disorders. Mutations in either the januskinase-2 (JAK-2) or the calreticulin (CALR) gene are characteristic for MPN and may result in enhanced proliferation of red blood cells, white blood cells and platelets, and thus increase the risk for vascular events. This study is a retrospective and descriptive analysis of records of patients, who underwent treatment for myeloproliferative syndromes at the Department of Hemato-Oncology of the University hospital Krems from 2008 to the end of 2015. Out of 250 patients, who were suspected for MPN, 51 patients displayed a JAK-2 V617F mutation. These were analyzed with regard to their blood values, gender, age at diagnosis, therapy and vascular events before and after diagnosis (during therapy). Of the 51 patients diagnosed with MPN and a JAK-2 V617F mutation, 33 suffered from PV, 15 from ET and 3 from MF. More men than women were diagnosed with MPN and the median age at diagnosis was 72 years. Acetylsalicylic acid, phlebotomy and Hydroxyurea were the most frequent therapies applied. In our study cohort, the most common vascular events were acute coronary syndrome and transitory ischemic attack. Thromboembolic events were effectively reduced by MPN therapy while no elevation in bleeding events could be observed.

SOHO State-of-the-Art Update and Next Questions: MPN

The discovery of the activating Janus kinase (JAK)2V617F mutation in 2005 in most patients with the classic Philadelphia chromosome-negative myeloproliferative neoplasms (MPN) spurred intense interest in research into these disorders, culminating in the identification of activating mutations in MPL in 2006 and indels in the gene encoding calreticulin (CALR) in 2013, thus providing additional mechanistic explanations for the universal activation of JAK-signal transducer and activator of transcription (JAK-STAT) observed in these conditions, and the success of the JAK1/2 inhibitor ruxolitinib, which first received regulatory approval in 2011. The field has continued to advance rapidly since then, and the past 2 years have witnessed important changes to the classification of MPN and diagnostic criteria for polycythemia vera (PV), novel insights into the mechanisms of bone marrow fibrosis in primary myelofibrosis (PMF), increasing appreciation of the biologic differences between essential thrombocythemia (ET), prefibrotic and overt PMF, and between primary and post-PV/ET myelofibrosis (MF). Additionally, the mechanisms through which mutant CALR drives JAK-STAT pathway activation and oncogenic transformation are now better understood. Although mastocytosis is no longer included under the broad heading of MPN in the 2016 revision to the World Health Organization classification, an important milestone in mastocytosis research was reached in 2017 with the regulatory approval of midostaurin for patients with advanced systemic mastocytosis (AdvSM). In this article, we review the major recent developments in the areas of PV, ET, and MF, and also briefly summarize the literature on midostaurin and other KIT inhibitors for patients with AdvSM.

A spotlight on the management of complications associated with myeloproliferative neoplasms: a clinician's perspective

INTRODUCTION

Myeloproliferative neoplasms (MPNs) are associated with a variety of symptoms and signs which cause major morbidity for the patients. The disorders are associated with increased incidence of thromboembolic and hemorrhagic events which can lead to complications and shortened life expectancy. Areas covered: Using systematic literature review and expert clinical and research experience the authors discuss strategies for the management of symptoms and signs including pruritus, fatigue, splenomegaly, and cytopenia. Cytoreduction including treatments to inhibit the JAK/STAT pathway are considered. Pathogenesis and prevention and treatment of thrombotic and hemorrhagic events and their management is addressed and the suggested management of the special situations such as surgery and pregnancy are discussed. Expert commentary: Management of disease has traditionally focused on symptom treatment and complication prevention but the discovery of driver mutations has led to treatments aiming to eliminate the clone, which should be the ultimate goal of therapy. A future challenge is to develop safe and effective MPN therapy and to personalize therapy.

Ruxolitinib vs best available therapy for ET intolerant or resistant to hydroxycarbamide

Treatments for high-risk essential thrombocythemia (ET) address thrombocytosis, disease-related symptoms, as well as risks of thrombosis, hemorrhage, transformation to myelofibrosis, and leukemia. Patients resistant/intolerant to hydroxycarbamide (HC) have a poor outlook. MAJIC (ISRCTN61925716) is a randomized phase 2 trial of ruxolitinib (JAK1/2 inhibitor) vs best available therapy (BAT) in ET and polycythemia vera patients resistant or intolerant to HC. Here, findings of MAJIC-ET are reported, where the modified intention-to-treat population included 58 and 52 patients randomized to receive ruxolitinib or BAT, respectively. There was no evidence of improvement in complete response within 1 year reported in 27 (46.6%) patients treated with ruxolitinib vs 23 (44.2%) with BAT (P = .40). At 2 years, rates of thrombosis, hemorrhage, and transformation were not significantly different; however, some disease-related symptoms improved in patients receiving ruxolitinib relative to BAT. Molecular responses were uncommon; there were 2 complete molecular responses (CMR) and 1 partial molecular response in CALR-positive ruxolitinib-treated patients. Transformation to myelofibrosis occurred in 1 CMR patient, presumably because of the emergence of a different clone, raising questions about the relevance of CMR in ET patients. Grade 3 and 4 anemia occurred in 19% and 0% of ruxolitinib vs 0% (both grades) in the BAT arm, and grade 3 and 4 thrombocytopenia in 5.2% and 1.7% of ruxolitinib vs 0% (both grades) of BAT-treated patients. Rates of discontinuation or treatment switching did not differ between the 2 trial arms. The MAJIC-ET trial suggests that ruxolitinib is not superior to current second-line treatments for ET. This trial was registered at www.isrctn.com as #ISRCTN61925716.

Clinical course and outcome of essential thrombocythemia and prefibrotic myelofibrosis according to the revised WHO 2016 diagnostic criteria

The recently revised World Health Organization (WHO) classification of myeloid neoplasms recognizes prefibrotic myelofibrosis (prePMF) as a distinct entity, characterized by well-defined histopathologic features together with minor clinical criteria (leukocytes, anemia, increased LDH, splenomegaly). The aim of the study was to examine the clinical relevance of distinguishing prePMF from essential thrombocythemia (ET). We identified in our database all patients affected with ET, prePMF and primary myelofibrosis (PMF) diagnosed according to 2008 WHO criteria with a bone marrow fibrosis grade 0-1 at diagnosis and one DNA sample to define the mutational status. The bone marrow morphology of all 404 identified patients was reviewed by an expert pathologist and patients were reclassified according to the 2016 WHO criteria. After reclassification, our cohort included 269 ET, 109 prePMF, and 26 myeloproliferative neoplasm unclassificable. In comparison with ET, patients with prePMF had higher leukocyte count, lower hemoglobin level, higher platelet count, higher LDH values, and higher number of circulating CD34-positive cells; they showed more frequently splenomegaly (all P values < ·001). CALR mutations were more frequent in prePMF than in ET (35·8% vs 17·8%, P < ·001). PrePMF patients had shorter overall survival (P < ·001) and a trend to a higher incidence of leukemic evolution (P ·067) compared to ET patients, while they did not differ in terms of thrombotic and bleeding complications. In conclusion, ET and prePMF diagnosed according to 2016 WHO criteria are two entities with a different clinical phenotype at diagnosis and a different clinical outcome.

Advances in understanding the pathogenesis of familial myeloproliferative neoplasms

Myeloproliferative neoplasms (MPNs) are generally acquired as a result of a somatic stem cell mutation leading to clonal expansion of myeloid precursors. In addition to sporadic cases, familial MPN occurs when one or several MPN affect different relatives of the same family. MPN driver mutations (JAK2, CALR, MPL) are somatically acquired also in familial cases, so a genetic predisposition to acquire one of the MPN driver mutations would be inherited, even though the causative germline mutations underlying familial MPN remain largely unknown. Recently some germline variants [ATG2B and GSKIP duplication, RBBP6 mutations, SH2B3 (LNK) mutations], which can cause familial MPN, have been reported but these mutations are rare and do not explain most familial cases. Patients with familial MPN show the same clinical features and suffer the same complications as those with sporadic disease. This review aims to offer up-to-date information regarding the genetics of familial MPN.

Diagnosis, risk stratification, and response evaluation in classical myeloproliferative neoplasms

Philadelphia-negative classical myeloproliferative neoplasms (MPNs) include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). The 2016 revision of the WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues includes new criteria for the diagnosis of these disorders. Somatic mutations in the 3 driver genes, that is, JAK2, CALR, and MPL, represent major diagnostic criteria in combination with hematologic and morphological abnormalities. PV is characterized by erythrocytosis with suppressed endogenous erythropoietin production, bone marrow panmyelosis, and JAK2 mutation. Thrombocytosis, bone marrow megakaryocytic proliferation, and presence of JAK2, CALR, or MPL mutation are the main diagnostic criteria for ET. PMF is characterized by bone marrow megakaryocytic proliferation, reticulin and/or collagen fibrosis, and presence of JAK2, CALR, or MPL mutation. Prefibrotic myelofibrosis represents an early phase of myelofibrosis, and is characterized by granulocytic/megakaryocytic proliferation and lack of reticulin fibrosis in the bone marrow. The genomic landscape of MPNs is more complex than initially thought and involves several mutant genes beyond the 3 drivers. Comutated, myeloid tumor-suppressor genes contribute to phenotypic variability, phenotypic shifts, and progression to more aggressive disorders. Patients with myeloid neoplasms are at variable risk of vascular complications, including arterial or venous thrombosis and bleeding. Current prognostic models are mainly based on clinical and hematologic parameters, but innovative models that include genetic data are being developed for both clinical and trial settings. In perspective, molecular profiling of MPNs might also allow for accurate evaluation and monitoring of response to innovative drugs that target the mutant clone.