Definition of subtypes of essential thrombocythaemia and relation to polycythaemia vera based on JAK2 V617F mutation status: a prospective study

Role of Portosystemic Shunt and Portal Vein Stent in Managing Portal Hypertension Due to Hematological Diseases

INTRODUCTION

Patients with hematological diseases experience complications related to portal hypertension, including life-threatening complications such as variceal bleeding.

METHODS

We analyzed the prognosis of patients with hematological diseases and portal hypertension treated with transjugular intrahepatic portosystemic shunts (TIPS) or portal vein stents. We retrospectively assessed patients with hematological diseases and portal hypertension who had variceal bleeding. We evaluated the characteristics and prognosis of the enrolled patients. A total of 11 patients with hematological diseases who underwent TIPS, or portal vein stenting, were evaluated.

RESULTS

The median follow-up period was 420 days. Of the 11 patients, eight showed resolution of portal hypertension and its complications following TIPS, or stent insertion. One patient experienced rebleeding due to incomplete resolution of portal hypertension, and two other patients also experienced rebleeding because they underwent TIPS closure or revision due to repetitive hepatic encephalopathy.

CONCLUSION

Portosystemic shunt and stent installation are effective treatment options for portal hypertension due to hematological diseases.

Management of classical Philadelphia chromosome-negative myeloproliferative neoplasms in Asia: consensus of the Asian Myeloid Working Group

Myeloproliferative neoplasms (MPN) are a heterogeneous group of clonal hematopoietic stem cell disorders characterized clinically by the proliferation of one or more hematopoietic lineage(s). The classical Philadelphia-chromosome (Ph)-negative MPNs include polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). The Asian Myeloid Working Group (AMWG) comprises representatives from fifteen Asian centers experienced in the management of MPN. This consensus from the AMWG aims to review the current evidence in the risk stratification and treatment of Ph-negative MPN, to identify management gaps for future improvement, and to offer pragmatic approaches for treatment commensurate with different levels of resources, drug availabilities and reimbursement policies in its constituent regions. The management of MPN should be patient-specific and based on accurate diagnostic and prognostic tools. In patients with PV, ET and early/prefibrotic PMF, symptoms and risk stratification will guide the need for early cytoreduction. In younger patients requiring cytoreduction and in those experiencing resistance or intolerance to hydroxyurea, recombinant interferon-α preparations (pegylated interferon-α 2A or ropeginterferon-α 2b) should be considered. In myelofibrosis, continuous risk assessment and symptom burden assessment are essential in guiding treatment selection. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) in MF should always be based on accurate risk stratification for disease-risk and post-HSCT outcome. Management of classical Ph-negative MPN entails accurate diagnosis, cytogenetic and molecular evaluation, risk stratification, and treatment strategies that are outcome-oriented (curative, disease modification, improvement of quality-of-life).

Molecular Studies for the Early Detection of Philadelphia-Negative Myeloproliferative Neoplasms

JAK2 V617F is the predominant driver mutation in patients with Philadelphia-negative myeloproliferative neoplasms (MPN). JAK2 mutations are also frequent in clonal hematopoiesis of indeterminate potential (CHIP) in otherwise "healthy" individuals. However, the period between mutation acquisition and MPN diagnosis (known as latency) varies widely between individuals, with JAK2 mutations detectable several decades before diagnosis and even from birth in some individuals. Here, we will review the current evidence on the biological factors, such as additional mutations and chronic inflammation, which influence clonal expansion and may determine why some JAK2-mutated individuals will progress to an overt neoplasm during their lifetime while others will not. We will also introduce several germline variants that predispose individuals to CHIP (as well as MPN) identified from genome-wide association studies. Finally, we will explore possible mutation screening or interventions that could help to minimize MPN-associated cardiovascular complications or even delay malignant progression.

Morphology of myeloproliferative neoplasms

Myeloproliferative neoplasms (MPN) are a group of clonal haematological malignancies first described by Dameshek in 1957. The Philadelphia-negative MPN that will be described are polycythaemia vera (PV), essential thrombocythaemia (ET), pre-fibrotic myelofibrosis and primary myelofibrosis (PMF). The blood and bone marrow morphology are essential in diagnosis, for WHO classification, establishing a baseline, monitoring response to treatment and identifying changes that may indicate disease progression. The blood film changes may be in any of the cellular elements. The key bone marrow features are architecture and cellularity, relative complement of individual cell types, reticulin content and bony structure. Megakaryocytes are the most abnormal cell and key to classification, as their number, location, size and cytology are all disease-defining. Reticulin content and grade are integral to assignment of the diagnosis of myelofibrosis. Even with careful assessment of all these features, not all cases fit neatly into the diagnostic entities; there is frequent overlap reflecting the biological disease continuum rather than distinct entities. Notwithstanding this, an accurate morphologic diagnosis in MPN is crucial due to the significant differences in prognosis between different subtypes and the availability of different therapies in the era of novel agents. The distinction between "reactive" and MPN is also not always straightforward and caution needs to be exercised given the prevalence of "triple negative" MPN. Here we describe the morphology of MPN including comments on changes with disease evolution and with treatment.

Allelic burden of Janus kinase 2 in a 6-month course of therapy for myeloproliferative neoplasms

BACKGROUND

Janus kinase 2 (JAK2) V617F gene mutation is an important marker for the diagnosis of Philadelphia negative Myeloproliferative neoplasms (MPN) which is subdivided into Polycythemia Vera (PV), Primary Myelofibrosis (PMF), and Essential Thrombocythemia (ET). The aim here is to investigate the JAK2 allele burden of the patients diagnosed with the subgroups of MPN and to demonstrate the alterations of hematological parameters and spleen size between diagnosis and 6 months of treatment.

METHODS

A total of 107 patients with the diagnosis of MPN and negative Philadelphia chromosome, 51 males and 56 females with a mean age of 59,74 ± 16,41 years, were included in the study. Diagnosis of MPN was based on the World Health Organization (WHO) criteria. Subgroups of MPN distributed as 49,5% ET, 46,7% PV, and 3,8% PMF. Findings such as the age of the patients, JAK-2 allele burden, and laboratory findings of splenomegaly were examined at the time of diagnosis, 3rd month, and 6th month. JAK2 allele burden and spleen size were re-evaluated in 6th month.

RESULTS

Our study confirmed the findings of high Hb, HCT, and RBC but low platelet values in PV patients with high JAK2 allele burden with respect to other groups, a positive correlation between JAK2 allele burden and LDH.

CONCLUSIONS

A novel finding of our study is, that there is not any reducing effect of the phlebotomy on JAK2 allele burden in PV patients whether they receive phlebotomy or not. Evaluation of the spleen size alteration during 6 months within the subgroups demonstrated a decrease in PV and ET groups whereas no statistically significant difference was found in the PMF group.

The role and mechanism of JAK2/STAT3 signaling pathway regulated by m6A methyltransferase KIAA1429 in osteosarcoma

Osteosarcoma (OS) is the most malignant bone tumor which mainly occurs in childhood or adolescence. The previous studies indicated that OS is difficult to treat. KIAA1429 is one of the components of m6A complex that regulating the process of m6A modification, which plays a crucial role in tumorigenesis. But the mechanism of KIAA1429 regulating OS cell identity was not entirely clear, which needs further investigate. RT-qPCR and western blotting were applied to determine KIAA1429 expression station in OS cells and tissues. To further detect the KIAA1429 function in OS cells, the ability of proliferation, migration and invasion were analyzed by Edu, wound-healing and transwell experiments respectively. Besides, RNA sequencing was also used to further find the downstream of KIAA1429 regulation and small molecule inhibitor was added to explore the specific role of signaling pathway. Our data found that KIAA1429 is up-regulated in human OS cell lines compared to the human osteoblast cells. Meanwhile, the deletion of KIAA1429 significantly decreased cell proliferation, migration, and invasion. Interestingly, the JAK2/STAT3 signal pathway was involved in KIAA1429 regulation on OS cell characters. The KIAA1429 eliminated OS cells exhibited a decreased activity of JAK2/STAT3 signal. And the addition of JAK2/STAT3 stimulator (colivelin) could distinctly rescue the decreased OS cells' proliferation, migration, and invasion upon KIAA1429 knockdown. In summary, these data demonstrated that KIAA1429/JAK2/STAT3 axis may a new target for OS therapy.

Reevaluation of cardiovascular risk factors for thrombotic events in 580 Japanese patients with essential thrombocythemia

Risk-adapted therapy is recommended to prevent thrombosis in essential thrombocythemia (ET) patients. An advanced age, a history of thrombosis, and the presence of the JAK2V617F mutation are well-defined risk factors for thrombosis in ET; however, the impact of cardiovascular risk (CVR) factors on thrombosis in ET remains elusive. Therefore, we herein investigated the impact of CVR factors on thrombosis in 580 ET patients who met the 2017 World Health Organization Classification diagnostic criteria. A univariate analysis identified hypertriglyceridemia and multiple CVR factors as strong risk factors for thrombosis (hazard ratio [HR] 3.530, 95% confidence interval [CI] 1.630-7.643, P = 0.001 and HR 3.368, 95% CI 1.284-8.833, P = 0.014, respectively) and hyper-LDL cholesterolemia as a potential risk factor (HR 2.191, 95% CI 0.966-4.971, P = 0.061). A multivariate analysis revealed that hypertriglyceridemia was an independent risk factor for thrombosis (HR 3.364, 95% CI 1.541-7.346, P = 0.002). Furthermore, poor thrombosis-free survival was observed in patients with a serum triglyceride level ≥ 1.2 mmol/L (HR = 2.592, P = 0.026 vs. < 1.2 mmol/L) or two or more CVR factors (P = 0.011 vs. no CVR factors and P = 0.005 vs. one CVR factor). These results revealed the impact of CVR factors on thrombosis in ET. Since CVR factors are manageable, lifestyle interventions, such as the control of serum triglyceride levels, may effectively prevent thrombosis in ET patients.

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.

Essential Thrombocythemia and Post-Essential Thrombocythemia Myelofibrosis: Updates on Diagnosis, Clinical Aspects, and Management

Although several decades have passed since the description of myeloproliferative neoplasms (MPN), many aspects of their pathophysiology have not been elucidated. In this review, we discuss the mutational landscape of patients with essential thrombocythemia (ET), prognostic scores and salient pathology, and clinical points. We discuss also the diagnostic challenges of differentiating ET from prefibrotic MF. We then focus on post-essential thrombocythemia myelofibrosis (post-ET MF), a rare subset of MPN that is usually studied in conjunction with post-polycythemia vera MF. The transition of ET to post-ET MF is not well studied on a molecular level, and we present available data. Patients with secondary MF could benefit from allogenic hematopoietic stem cell transplantation, and we present available data focusing on post-ET MF.

Anagrelide in essential thrombocythemia: Efficacy and long-term consequences in young patient population

According to the current treatment recommendations, anagrelide, an oral antiplatelet agent, is recommended as a second-line therapy for patients with high-risk essential thrombocythemia experiencing intolerance or refractoriness to first-line approach, such as hydroxyurea or pegylated interferon alpha-2a. If there is a need for introduction of cytoreductive treatment in young patients with a perspective of lifelong exposure, both the efficacy and long-term outcomes should be known. We present the analysis of 48 young patients, diagnosed with essential thrombocythemia below the age of 60, who were exposed to anagrelide treatment for over 10 years. Our observations show that the highest proportion of complete remissions without adverse events and disease progression is seen in the JAK2-mutated patients. By evaluating the changes in hemoglobin concentration and serum erythropoietin throughout the study, we were able to reveal the development of progressive anemia, resulting from diminished susceptibility to erythropoietin and unrelated to bone marrow fibrosis, in patients harboring CALR mutation. Additionally, occurrence of new bone marrow fibrosis was confirmed in seven JAK2-unmutated patients at the end of the study. In summary, in young patient population, we recommend limiting the use of anagrelide to JAK2-mutated subgroup, reducing exposure time and underline the importance of periodic monitoring for the presence of bone marrow fibrosis.

The roles of sex and genetics in the MPN

The Philadelphia chromosome negative myeloproliferative neoplasms(MPNs), polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) are acquired hematopoietic stem cell disorders driven by activating mutations of intracellular signal transduction pathways that control the production of circulating blood cells. The MPN are characterized clinically by marked variation in degrees of vascular risk, familial clustering, and evolution to myelofibrosis and acute leukemia. MPN disease presentations and outcomes are highly variable, and are markedly influenced by both sex and germline genetic variation. This chapter will focus on the evidence of sex and germline genetic background as modifiers of MPN development and outcomes. Large population genome wide association studies in both clonal hematopoiesis and MPN have revealed novel mechanisms, including inflammatory pathways and genomic instability, which further our understanding of how sex and genetic background mediate MPN risk. Recent advances in our understanding of clonal hematopoiesis and MPN development in various contexts informs the mechanisms by which sex, inflammation, exposures and genetics influence MPN incidence and outcomes, and provide opportunities to develop new strategies for prognostics and therapeutics in the MPN.

Assessment of relation between JAK2 gene and thrombosis in myeloproliferative neoplasms

Background Thrombotic complications are the most considerable etiology causing morbidity and mortality in patients with philadelphia (Ph) negative myeloproliferative neoplasms (MPN). There are many studies evaluating the association of JAK2 mutation and risk of thrombosis in MPN with inconclusive results. We also investigated the relation between JAK2 mutation in all Ph negative MPN and thrombosis. Material and Methods Thrombotic events and demographic features of 177 patients with Ph negative MPN were evaluated retrospectively. Results JAK2 V617 F mutation was detected in 57% of patients with essential thrombocythemia (ET), %90.3 of pateints with polycythemia vera (PV), 100% of pateints with primary myelofibrosis (PMF). Thrombotic complications occured more frequently with JAK2 mutation in all MPN patients than without (p=0.014). In JAK 2 mutation positive groups, the median age, thrombosis risk scores and leucocyte values are higher, splenomegaly and arterial and/or venous thrombosis are detected more frequently (p

Hydralazine Associated With Reduced Therapeutic Phlebotomy Frequency in a Nationwide Cohort Study: Real-World Effectiveness for Drug Repurposing

Background: Therapeutic phlebotomy, known as scheduled bloodletting, has been the main method for managing erythrocytosis symptoms and thrombocytosis-associated complications in various blood disorders. One of the major indications for phlebotomy is polycythemia vera (PV). The main goal of current treatment strategies for patients who require phlebotomy is to prevent thrombohemorrhagic complications rather than to prolong survival or lessen the risk of myelofibrotic or leukemic progression. Additional cytoreductive therapy is recommended for high-risk PV, for which the common first-line drug is hydroxyurea. However, recent evidence suggests that phlebotomy may not reduce the risk of thrombosis in patients with PV. Further evidence suggests that patients with PV treated with hydroxyurea who require three or more phlebotomy procedures per year have a higher risk of thrombotic complications.

Methods: We hypothesized that a drug-repurposing strategy of utilizing antineoplastic drugs for patients who require phlebotomy would result in greater benefits than would phlebotomy. The antihypertensive hydralazine and the anticonvulsant valproate, which have both been reported to have antineoplastic activity that mimics cytoreductive agents, were selected as candidates for the drug-repositioning strategy in a retrospective cohort study. We measured the hazard ratios (HR) and the frequencies of phlebotomy in patients with prescriptions for hydralazine or valproate or the two drugs in combination by using data from Taiwan’s National Health Insurance Research Database from 2000 to 2015 (n = 1,936,512).

Results: The HRs of undergoing phlebotomy in groups with hydralazine, valproate, and combination hydralazine–valproate prescriptions were reduced to 0.729 (p = 0.047), 0.887 (p = 0.196), and 0.621 (p = 0.022), respectively. The frequency of undergoing phlebotomy decreased from 2.27 to 1.99, 2.01, and 1.86 per person-year (p = 0.015), respectively. However, no significant differences were observed for the hydralazine group or the hydralazine–valproate combination group.

Conclusion: Whether a repurposed drug can serve as a cytoreductive agent for patients who require phlebotomy depends on its risk–benefit balance. We suggest that hydralazine, instead of the hydralazine–valproate combination, is a reasonable alternative for patients who require regular phlebotomy.

Low-risk polycythemia vera and essential thrombocythemia: management considerations and future directions

Thrombotic events are a distinctive feature of the myeloproliferative neoplasms (MPNs) polycythemia vera (PV) and essential thrombocythemia (ET). Patients with these MPNs may also experience a poor quality of life secondary to symptom burden, as well as progression of disease to acute leukemia or myelofibrosis. Over the years, various risk stratification methods have evolved in order to attempt to predict thrombotic risk, which is the largest contributor of morbidity and mortality in these patients. More than half of PV and ET patients are low- or intermediate-risk disease status at the time of diagnosis. While therapeutic development is presently focused on high-risk patients, there is a paucity of therapies, outside of aspirin and therapeutic phlebotomy, which can reduce the thrombotic risk or delay disease progression in low-risk patients. In this review, we first describe the various complications that patients with PV and ET experience, and then detail our evolving understanding of risk stratification in these diseases. We then highlight the available evidence on the management of low-risk PV and ET and include a description of novel therapies currently under investigation in this space. We conclude with recommendations for future directions to advance our understanding and improve the treatment of low-risk PV and ET.

Comparison of Clinical and Hematological Parameters of Janus Kinase 2, Calreticulin or Myeloproliferative Leukemia Virus Oncogene Mutant Essential Thrombocythemia and Triple-Negative Essential Thrombocythemia

Introduction

Essential thrombocythemia (ET) is one of the chronic myeloproliferative neoplasms. While Janus kinase 2 (JAK2) V617F mutation is defined in more than half of the patients with ET, calreticulin (CALR) or myeloproliferative leukemia virus oncogene (MPL) mutations are encountered more rarely. The discovery of the JAK2 V617F mutation in 2005, followed by the recognition of MPL and CALR mutations, brought up the idea of subdividing ET according to the mutation status. Our aim in this study is to investigate whether genetic mutations detected in patients diagnosed with ET cause a different clinical phenotype compared to triple-negative ET.

Methods

This retrospective study was conducted by evaluating the patients who were followed up with the diagnosis of ET in the hematology clinic of two tertiary centers in Turkey between 2009 and 2021. Patients with negative JAK2, CALR, and MPL mutations and meeting the diagnostic criteria for ET were defined as triple-negative ET. The patients were divided into two groups as triple-negative ET and mutation-positive ET according to the presence of a mutation. It was investigated whether there was a difference between these two groups in terms of demographic, laboratory, and clinical characteristics.

Results

A total of 109 patients were included in the study. The mean age of these patients was 54 (18-91) years and 85 (78%) patients were females. A total of 48 patients (44.0%) had JAK2 mutation, six (5.5%) had CALR mutation, and one (0.9%) had MPL mutation. It was observed that there was a significant difference between the two groups in terms of gender, mean age, and hemoglobin value. While 87% of patients with triple-negative ET were females, this rate was 69% in patients with mutation-positive ET (p = 0.036). The mean age was 41.8 years in triple-negative ET and 67.1 years in patients with mutation-positive ET (p = 0.0001). While the mean hemoglobin value was 12.9 g/dl in patients with triple-negative ET, it was 14.4 g/dl in patients with mutation-positive ET (p = 0.0001).

Conclusion

It has been observed that ET with JAK2, CALR, or MPL mutations may have different phenotypic features compared to triple-negative ET, resulting in a clinical condition consisting of older patients with a higher erythrocyte count.

Insights into the Potential Mechanisms of JAK2V617F Somatic Mutation Contributing Distinct Phenotypes in Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPN) are a group of blood cancers in which the bone marrow (BM) produces an overabundance of erythrocyte, white blood cells, or platelets. Philadelphia chromosome-negative MPN has three subtypes, including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). The over proliferation of blood cells is often associated with somatic mutations, such as JAK2, CALR, and MPL. JAK2V617F is present in 95% of PV and 50–60% of ET and PMF. Based on current molecular dynamics simulations of full JAK2 and the crystal structure of individual domains, it suggests that JAK2 maintains basal activity through self-inhibition, whereas other domains and linkers directly/indirectly enhance this self-inhibited state. Nevertheless, the JAK2V617F mutation is not the only determinant of MPN phenotype, as many normal individuals carry the JAK2V617F mutation without a disease phenotype. Here we review the major MPN phenotypes, JAK-STAT pathways, and mechanisms of development based on structural biology, while also describing the impact of other contributing factors such as gene mutation allele burden, JAK-STAT-related signaling pathways, epigenetic modifications, immune responses, and lifestyle on different MPN phenotypes. The cross-linking of these elements constitutes a complex network of interactions and generates differences in individual and cellular contexts that determine the phenotypic development of MPN.

The JAK2 mutation

Myeloproliferative neoplasms (MPNs) are clonal hematopoietic stem cell (HSC) disorders with overproduction of mature myeloid blood cells, including essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF). In 2005, several groups identified a single gain-of-function point mutation JAK2V617F in the majority of MPN patients. The JAK2V617F mutation confers cytokine independent proliferation to hematopoietic progenitor cells by constitutively activating canonical and non-canonical downstream pathways. In this chapter, we focus on (1) the regulation of JAK2, (2) the molecular mechanisms used by JAK2V617F to induce MPNs, (3) the factors that are involved in the phenotypic diversity in MPNs, and (4) the effects of JAK2V617F on hematopoietic stem cells (HSCs). The discovery of the JAK2V617F mutation led to a comprehensive understanding of MPN; however, the question still remains about how one mutation can give rise to three distinct disease entities. Various mechanisms have been proposed, including JAK2V617F allele burden, differential STAT signaling, and host genetic modifiers. In vivo modeling of JAK2V617F has dramatically enhanced the understanding of the pathophysiology of the disease and provided the pre-clinical platform. Interestingly, most of these models do not show an increased hematopoietic stem cell self-renewal and function compared to wildtype controls, raising the question of whether JAK2V617F alone is sufficient to give a clonal advantage in MPN patients. In addition, the advent of modern sequencing technologies has led to a broader understanding of the mutational landscape and detailed JAK2V617F clonal architecture in MPN patients.

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.

Telomere Attrition and Clonal Hematopoiesis of Indeterminate Potential in Cardiovascular Disease

Clinical evidence suggests that conventional cardiovascular disease (CVD) risk factors cannot explain all CVD incidences. Recent studies have shown that telomere attrition, clonal hematopoiesis of indeterminate potential (CHIP), and atherosclerosis (telomere-CHIP-atherosclerosis, TCA) evolve to play a crucial role in CVD. Telomere dynamics and telomerase have an important relationship with age-related CVD. Telomere attrition is associated with CHIP. CHIP is commonly observed in elderly patients. It is characterized by an increase in blood cell clones with somatic mutations, resulting in an increased risk of hematological cancer and atherosclerotic CVD. The most common gene mutations are DNA methyltransferase 3 alpha (DNMT3A), Tet methylcytosine dioxygenase 2 (TET2), and additional sex combs-like 1 (ASXL1). Telomeres, CHIP, and atherosclerosis increase chronic inflammation and proinflammatory cytokine expression. Currently, their epidemiology and detailed mechanisms related to the TCA axis remain incompletely understood. In this article, we reviewed recent research results regarding the development of telomeres and CHIP and their relationship with atherosclerotic CVD.

Unmet clinical needs in the management of CALR-mutated essential thrombocythaemia: a consensus-based proposal from the European LeukemiaNet

Recommendations regarding management of essential thrombocythaemia rely on studies done before the discovery of the CALR mutation. On May 20, 2020, the European LeukemiaNet annual meeting was held with the goal to identify unmet clinical needs in myeloproliferative neoplasms. Because patients with a CALR mutation have specific clinical characteristics, treatment of CALR-mutated essential thrombocythaemia was considered an unmet clinical need by the European LeukemiaNet. The elaboration of a consensus document with recommendations according to current evidence was proposed as a solution for resolving uncertainties in the treatment of CALR-mutated essential thrombocythaemia. A steering committee comprising four European LeukemiaNet members was then formed and a panel of ten experts in the field was recruited. The experts proposed 51 potential unmet clinical needs in the management of CALR-mutated essential thrombocythaemia and were asked to score the relevance of each topic. Those topics that obtained the highest scores as relevant unmet clinical needs were identified, including antiplatelet therapy in patients at low risk, definition of extreme thrombocytosis and its management in patients at low risk, indications of cytoreduction and targets of therapy, first-line treatment of choice in young patients (<60 years), and management of pregnancy. After the steering committee revised the available evidence for each topic, a consensus on management and proposal for improving knowledge was achieved by use of an email-based, two round, Delphi approach. Consensus was achieved when 90% of the panellists agreed with a statement and included 14 recommendations and six solution proposals. Key recommendations included careful observation for asymptomatic patients with classical, low-risk, CALR-mutated essential thrombocythaemia without cardiovascular risk factors; caution in the use of antiplatelet therapy for symptomatic patients at low risk with platelet counts of 1000-1500 × 109 platelets per L, in such cases cytoreduction is an adequate option, especially if adquired Von Willebrand disease is present; cytoreduction is recommended for extreme thrombocytosis (platelet count >1500 × 109 platelets per L) with pegylated interferon alfa being the preferred option for younger patients; both hydroxycarbamide and anagrelide might be given to patients ineligible for pegylated interferon alfa; and treatment algorithms for patients with high-risk pregnancies should not be changed according to genotype. The European LeukemiaNet proposes to use these recommendations in the routine management of patients with CALR-mutated essential thrombocythaemia, and designing new clinical studies in this field might be useful.

Arterial Thrombosis in Cancer Patients: An Update

Cancer is associated with an increased incidence of both venous thromboembolism (VTE) and arterial thrombosis (cardiovascular events and ischemic stroke). Cancer-associated arterial thrombotic events are less well studied than VTE, but increasingly recognized, particularly in specific malignancies and in association with specific anticancer therapies. The pathogenesis of arterial thrombotic events in cancer is complex and involves generation of tumor-associated procoagulant factors and a variety of alterations in platelet function as well as in the coagulation and fibrinolytic systems, and endothelial injury and dysfunction, that combine to produce hypercoagulability. The multifactorial interaction between this prothrombotic state, the individual cardiovascular risk, advanced age and presence of comorbidities, and the specific neoplasm characteristics and therapy, may induce the vascular events. Recent studies based on population databases and prospective or retrospective analyses with prolonged follow-up highlight that cancer patients experience an increased (approximately 1.5-2-fold) risk of both cerebrovascular and cardiovascular events compared with noncancer individuals, which peaks in the time period of the diagnosis of cancer but may persist for years. Beyond the type of cancer, the risk reflects the tumor burden, being higher in advanced stages and metastatic cancers. The occurrence of arterial thromboembolic events is also associated with increased overall mortality. We here present an update of the pathophysiology, risk factors, clinical evidence, and treatment considerations on cancer-associated arterial thrombosis, in the light of the need for specific multidisciplinary prevention and surveillance strategies in this setting, in the frame of cardio-oncology approaches.

Bleeding diathesis in mice lacking JAK2 in platelets

The tyrosine kinase JAK2 is a critical component of intracellular JAK/STAT cytokine signaling cascades that is prevalent in hematopoietic cells, such as hematopoietic stem cells and megakaryocytes (MKs). Individuals expressing the somatic JAK2 V617F mutation commonly develop myeloproliferative neoplasms (MPNs) associated with venous and arterial thrombosis, a leading cause of mortality. The role of JAK2 in hemostasis remains unclear. We investigated the role of JAK2 in platelet hemostatic function using Jak2fl/fl Pf4-Cre (Jak2Plt-/-) mice lacking JAK2 in platelets and MKs. Jak2Plt-/- mice developed MK hyperplasia and splenomegaly associated with severe thrombocytosis and bleeding. This notion was supported by failure to occlude in a ferric chloride carotid artery injury model and by a cremaster muscle laser-induced injury assay, in which Jak2Plt-/- platelets failed to form stable thrombi. Jak2Plt-/- platelets formed thrombi poorly after adhesion to type 1 collagen under arterial shear rates. Jak2Plt-/- platelets spread poorly on collagen under static conditions or on fibrinogen in response to the collagen receptor GPVI-specific agonist, collagen-related peptide (CRP). After activation with collagen, CRP, or the CLEC-2 agonist rhodocytin, Jak2Plt-/- platelets displayed decreased α-granule secretion and integrin αIIbβ3 activation or aggregation, but showed normal responses to thrombin. Jak2Plt-/- platelets had impaired intracellular signaling when activated via GPVI, as assessed by tyrosine phosphorylation. Together, the results show that JAK2 deletion impairs platelet immunoreceptor tyrosine-based activation motif signaling and hemostatic function in mice and suggest that aberrant JAK2 signaling in patients with MPNs affects GPVI signaling, leading to hemostatic platelet function.

Gemcitabine and APG-1252, a novel small molecule inhibitor of BCL-2/BCL-XL, display a synergistic antitumor effect in nasopharyngeal carcinoma through the JAK-2/STAT3/MCL-1 signaling pathway

Advanced nasopharyngeal carcinoma (NPC) has a poor prognosis, with an unfavorable response to palliative chemotherapy. Unfortunately, there are few effective therapeutic regimens. Therefore, we require novel treatment strategies with enhanced efficacy. The present study aimed to investigate the antitumor efficacy of APG-1252-M1, a dual inhibitor of BCL-2/BCL-XL, as a single agent and combined with gemcitabine. We applied various apoptotic assays and used subcutaneous transplanted NPC model to assess the in vitro and in vivo antitumor activity. Moreover, phospho-tyrosine kinase array was used to investigate the combined therapy’s potential synergistic mechanism. In addition, further validation was performed using immunohistochemistry and western blotting. In vitro, we observed that APG-1252-M1 had moderate antitumor activity toward NPC cells; however, it markedly improved gemcitabine’s ability to promote NPC cell apoptosis and suppress invasion, migration, and proliferation. Specifically, APG-1252 plus gemcitabine exhibited even remarkable antitumor activity in vivo. Mechanistically, the drug combination synergistically suppressed NPC by activating caspase-dependent pathways, blocking the phospho (p)-JAK-2/STAT3/MCL-1 signaling pathway, and inhibiting epithelial-mesenchymal transition. In conclusion, the results indicated that the combination of APG-1252 and gemcitabine has synergistic anticancer activities against NPC, providing a promising treatment modality for patients with NPC.

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

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

Clinical insights into the origins of thrombosis in myeloproliferative neoplasms

Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs), polycythemia vera, essential thrombocythemia, and primary myelofibrosis, are hematopoietic stem cell disorders that are defined by activating mutations in signal transduction pathways and are characterized clinically by the overproduction of platelets, red blood cells, and neutrophils, significant burden of disease-specific symptoms, and high rates of vascular events. The focus of this review is to critically reevaluate the clinical burden of thrombosis in MPNs, to review the clinical associations among clonal hematopoiesis, JAK2V617F burden, inflammation, and thrombosis, and to provide insights into novel primary and secondary thrombosis-prevention strategies.

Inflammatory Pathophysiology as a Contributor to Myeloproliferative Neoplasms

Myeloid neoplasms, including acute myeloid leukemia (AML), myeloproliferative neoplasms (MPNs), and myelodysplastic syndromes (MDS), feature clonal dominance and remodeling of the bone marrow niche in a manner that promotes malignant over non-malignant hematopoiesis. This take-over of hematopoiesis by the malignant clone is hypothesized to include hyperactivation of inflammatory signaling and overproduction of inflammatory cytokines. In the Ph-negative MPNs, inflammatory cytokines are considered to be responsible for a highly deleterious pathophysiologic process: the phenotypic transformation of polycythemia vera (PV) or essential thrombocythemia (ET) to secondary myelofibrosis (MF), and the equivalent emergence of primary myelofibrosis (PMF). Bone marrow fibrosis itself is thought to be mediated heavily by the cytokine TGF-β, and possibly other cytokines produced as a result of hyperactivated JAK2 kinase in the malignant clone. MF also features extramedullary hematopoiesis and progression to bone marrow failure, both of which may be mediated in part by responses to cytokines. In MF, elevated levels of individual cytokines in plasma are adverse prognostic indicators: elevated IL-8/CXCL8, in particular, predicts risk of transformation of MF to secondary AML (sAML). Tumor necrosis factor (TNF, also known as TNFα), may underlie malignant clonal dominance, based on results from mouse models. Human PV and ET, as well as MF, harbor overproduction of multiple cytokines, above what is observed in normal aging, which can lead to cellular signaling abnormalities separate from those directly mediated by hyperactivated JAK2 or MPL kinases. Evidence that NFκB pathway signaling is frequently hyperactivated in a pan-hematopoietic pattern in MPNs, including in cells outside the malignant clone, emphasizes that MPNs are pan-hematopoietic diseases, which remodel the bone marrow milieu to favor persistence of the malignancy. Clinical evidence that JAK2 inhibition by ruxolitinib in MF neither reliably reduces malignant clonal burden nor eliminates cytokine elevations, suggests targeting cytokine mediated signaling as a therapeutic strategy, which is being pursued in new clinical trials. Greater knowledge of inflammatory pathophysiology in MPNs can therefore contribute to the development of more effective therapy.

Screening of somatic mutations in the JAK2 and CALR genes by high-resolution melting curve analysis

Somatic mutations associated with oncological diseases, including Ph-myeloproliferative neoplasms (Ph-MPN), are very diverse, occur with different frequencies and different allelic burden levels. Therefore, at the initial stage of performing molecular-genetic diagnostic procedures, it is desirable to be able to conduct screening tests in the laboratory. This is especially important when analyzing rare and diverse mutations. Analysis of high resolution melting curves (HRM analysis), which has high sensitivity and is suitable for screening all types of mutations, in a number of studies is proposed for the analysis of Ph-MPN associated mutations in the JAK2 and CALR genes. For analysis of somatic mutations in the majority of literature sources that we reviewed, the authors use the LightCycler (Roche) thermocycler and much rarely the CFX96 (Bio-Rad), which is often presented in Russian scientific and practical and medical organizations. The aim of the study was to screen the somatic JAK2 and CALR mutations by HRM analysis using the CFX96 thermocycler and the Precision Melt Analysis software (Bio-Rad, USA) for patients with Ph-MPN. In the present research, HRM analysis was conducted on the DNA samples from patients with mutations in the JAK2 or in the CALR gene. The Precision Melt Analysis software identified all variants of the analyzed mutations, both a single nucleotide substitution in the JAK2 gene (with allelic burden level in the range of 5-40%), and various indel mutations in the CALR gene (with allelic burden level in the range of 40-50%) Therefore, the HRM analysis that was conducted on the CFX96 allows screening of highly specific mutation for the diagnosis of Ph-MPN in the exon 14 of the JAK2 gene and in the exon 9 of the CALR gene. The inclusion of this screening research in the laboratory testing algorithm improves the efficiency and accessibility of molecular genetic technologies in the diagnosis of Ph-MPN.

Recent Advances in the Use of Molecular Analyses to Inform the Diagnosis and Prognosis of Patients with Polycythaemia Vera

Genetic studies in the past decade have improved our understanding of the molecular basis of the BCR-ABL1-negative myeloproliferative neoplasm (MPN) polycythaemia vera (PV). Such breakthroughs include the discovery of the JAK2V617F driver mutation in approximately 95% of patients with PV, as well as some very rare cases of familial hereditary MPN caused by inherited germline mutations. Patients with PV often progress to fibrosis or acute myeloid leukaemia, both associated with very poor clinical outcome. Moreover, thrombosis and major bleeding are the principal causes of morbidity and mortality. As a result of increasingly available and economical next-generation sequencing technologies, mutational studies have revealed the prognostic relevance of a few somatic mutations in terms of thrombotic risk and risk of transformation, helping to improve the risk stratification of patients with PV. Finally, knowledge of the molecular basis of PV has helped identify targets for directed therapy. The constitutive activation of the tyrosine kinase JAK2 is targeted by ruxolitinib, a JAK1/JAK2 tyrosine kinase inhibitor for PV patients who are resistant or intolerant to cytoreductive treatment with hydroxyurea. Other molecular mechanisms have also been revealed, and numerous agents are in various stages of development. Here, we will provide an update of the recent published literature on how molecular testing can improve the diagnosis and prognosis of patients with PV and present recent advances that may have prognostic value in the near future.

Advances in the Treatment of Polycythemia Vera: Trends in Disease Management

Treatment modalities for polycythemia vera (PV) have evolved over time. Phlebotomy and low-dose aspirin suffice in low-risk patients, but cytoreductive therapies are indicated in all high-risk patients (age ≥ 65 years or those with a history of PV-related thrombotic event) and may be considered for low-risk patients with progressively increasing splenomegaly, progressively increasing leucocyte and platelet counts, and for those who do not tolerate phlebotomy. Hydroxyurea/hydroxycarbamide or interferons can be used as first-line drugs. Hydroxyurea may not be tolerated by some patients, and it also carries risk of myelosuppression. Interferon alfa is especially useful for PV symptoms, and the newer preparation, ropeginterferon alfa-2b, has lesser incidence of flu-like reactions. Ruxolitinib reduces the JAK2V617F mutation burden and is used as a second-line drug. Anagrelide reduces platelet production and can be used in conjunction with hydroxyurea in patients with excessive thrombocytosis. The alkylating agent, busulfan, can also be used as a last resort in patients with a limited life expectancy. Prospective future treatments include givinostat, a histone deacetylase inhibitor, and idasanutlin, a murine double minute 2 antagonist.

Evaluation of Therapeutic Strategies to Reduce the Number of Thrombotic Events in Patients With Polycythemia Vera and Essential Thrombocythemia

Thrombosis is the largest contributor to morbidity and mortality in patients with polycythemia vera (PV) and essential thrombocythemia (ET). Our understanding of the risk factors and pathophysiology of thrombosis in PV and ET patients is developing, including recent insights into the role of aberrant platelet-neutrophil interactions, JAK2 mutated endothelial cells and the pro-thrombotic inflammatory milieu. To date, few available therapies have demonstrated the ability to reduce the thrombotic burden in patients with these diseases. Although numerous therapeutic agents have been investigated in both PV and ET patients, few studies are designed to assess their impact on thrombotic events. In this review, we first describe the burden of thrombosis in patients with these myeloproliferative neoplasms (MPNs) and briefly explore their pathophysiologic mechanisms. We then critically assess and summarize the evidence behind currently available therapies with attention toward thrombotic endpoints. Finally, we describe a path forward for clinical research in MPNs that involves surrogate endpoint validation, biomarker development, and clinical trial design strategies in order to accurately assess reduction of thrombotic events when evaluating novel therapies.

Low-Risk Essential Thrombocythemia: A Comprehensive Review

Essential thrombocythemia (ET) is a chronic myeloproliferative neoplasm characterized by a persistently elevated platelet count in the absence of a secondary cause. The clinical consequences of uncontrolled thrombocytosis can include both thrombosis and hemorrhage. Patients with features conferring a “high risk” of vascular events benefit from reduction of the platelet count through cytoreductive therapy. The management of patients who lack such high-risk features has until recently been less well defined, but it is now apparent that many require minimal or even no intervention. In this review, we discuss the diagnostic pathway for younger patients with unexplained thrombocytosis, including screening molecular investigations, the role of bone marrow biopsy, and investigations in those patients negative for the classic myeloproliferative neoplasm driver mutations (JAK2, CALR, MPL). We discuss conventional and novel risk stratification methods in essential thrombocythemia and how these can be best applied in clinical practice, particularly in the era of more comprehensive genomic testing. The treatment approach for “low risk” patients is discussed including antiplatelets and the options for cytoreductive therapy, if indicated, together with areas of clinical need for future study.

[Pathological characteristics of megakaryocytes in myeloproliferative neoplasms and their correlation with driver gene mutations]

Objective: To investigate the pathological characteristics of megakaryocytes in myeloproliferative neoplasms(MPN)and their correlations with driver gene mutations. Methods: Trephine specimens administered for 160 patients with MPN from February 2012 to October 2017 were reevaluated according to the World Health Organization(WHO)'s(2016)diagnostic criteria. Results: This cohort of patients included 72(45.0%)men, with the median age of 59(range, 13-87)years, comprising 39 with polycythemia vera(PV), 33 with essential thrombocythemia(ET), 37 with prefibrotic/early-primary myelofibrosis(pre-PMF), 37 with overt PMF, 1 with post-ET MF, 2 with post-PV MF, and 11 with MPN-unclassifiable(MPN-U)after the re-diagnosis. With PV, ET, pre-PMF, and overt PMF changes, proportions of dense clusters, hypolobulated nuclei, and naked nuclei of megakaryocytes gradually increased, whereas erythropoiesis gradually decreased. Proportions of reticulin, collagen, and osteosclerosis grades of ≥1 also increased. Dense clusters, hypolobulated nuclei, and naked nuclei of megakaryocytes were negatively correlated with erythropoiesis and positively correlated with granulopoiesis and fibrosis. In patients with pre- and overt PMF, dense clusters and naked nuclei of megakaryocytes were positively correlated with fibrosis. Patients with JAK2V617F MPN had significantly increased erythropoiesis(P=0.022). Patients with CALR-mutated MPN were characterized by increased loose and dense clusters; paratrabecular distribution and naked nuclei of megakaryocytes(P=0.055, P=0.002, P=0.018, P=0.008); and increased reticulin, collagen, and osteosclerosis(P=0.003, P<0.001, P=0.001). In patients with pre- and overt PMF, patients with JAK2V617F had increased cellularity(P=0.037). CALR-mutated patients had increased dense clusters and giant sizes of megakaryocytes, collagen, and osteosclerosis(P=0.055, P=0.059, P=0.011, P=0.046). Conclusion: Megakaryocytes showed abnormal MPN morphology and distribution, which were related to fibrosis. CALR mutation was probably associated with abnormal morphology and distribution of megakaryocytes and fibrosis.

Clinical Characteristics and Management of Cerebral Venous Sinus Thrombosis in Patients with Essential Thrombocythemia

BACKGROUND AND OBJECTIVE

Essential thrombocythemia (ET) is a rare cause of cerebral venous sinus thrombosis (CVST). Analysis of the risk factors and treatment therapies of CVST in ET has yielded controversial findings.

SUBJECTS AND METHODS

We retrospectively investigated the clinical characteristics of CVST events in ET and compared baseline characteristics, causative factors, hematological effects, and treatments between ET patients with and without CVST.

RESULTS

Overall, 91 of 115 patients who met the ET diagnosis were included in this study. Among them, 23 (25.27%) patients met the diagnostic criteria of ET with CVST for inclusion, 14 (60.87%) of whom were females, with a median age of 34 (range 25-50). CVST diagnosis was made concomitantly to ET in 19 patients (82.61%). The most common symptom and sites of thrombosis of CVST was an acute or subacute headache and sigmoid sinuses, respectively. Compared with ET patients without CVST, ET patients with CVST were significantly younger (37.65±14.45 vs 60.93±13.46, P<0.001) and had lower prevalence of hypertension (4.34 vs 32.35%, P=0.003) and coronary artery disease (0 vs 14.71%, P = 0.045). Patients with CVST presented with significant lower platelet count (510.39±176.71 vs 750.82±249.10, P< 0.001) and higher score of IPSET-thrombosis (P=0.017). Multivariate logistic regression analysis indicated that age (P=0.002, OR 1.096, 95% CI 1.035-1.161), at least one CVRF (P = 0.024, OR 0.037, 95% CI 0.002-0.649), platelet count (P=0.045, OR 0.994, 95% CI 0.989-1.001), and lower percentage of antiplatelet therapy (P=0.035, OR 0.307, 95% CI 0.001-1.280) significantly contributed to the risk of CVST in ET.

CONCLUSION

Most patients (95.65%) had a favorable outcome without recurrence after standard anticoagulant and cytoreductive treatment at last follow-up. These findings indicate that CVST may be the initial presentation of ET, with its detection crucial for early diagnosis and appropriate management. Anticoagulant and cytoreductive therapies should be recommended for preventing ET-related CVST with JAK2 V617F mutation.

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.

Applied genomics in MPN presentation

Polycythemia vera, essential thrombocytosis (ET), and primary myelofibrosis (PMF) are grouped together as myeloproliferative neoplasms (MPNs) because of shared clinical, pathologic, and molecular features. The 2005 discovery of the driver mutation JAK2V617F, found in more than 70% of individuals with MPNs and 98% of those with PV, has transformed the diagnosis and management of MPNs. Although PV is the most common phenotype associated with JAK2V617F, roughly 60% of individuals with ET or PMF also have the mutation, and JAK2V617F is now recognized as a common lesion in clonal hematopoiesis (CH). JAK2V617F+ CH and MPN are indolent disorders that evolve over time, with transitions to different disease phases, transformation to bone marrow failure or leukemia, and high thrombosis rates. Genomic assessment has taken center stage as an important tool to define disease phenotype, disease burden, prognosis, and even thrombosis risk of MPNs. Genomics has also unveiled the causes and factors that modify the risk of acquiring and expanding CH and MPNs and points to new pathways for targeted therapies to treat and ultimately prevent them. Genomic assessment of patients with MPNs, like other cancers, enables the clinician to capitalize on large population data sets to inform the individual patient of risk, identify treatment, and improve outcomes.

Cumulative visual impact of two coagulability disorders: A case report

Cumulative visual impact of two coagulability disorders were reviewed by presenting a case of a young female patient with a spontaneous abortion and two thromboembolic events in 8 years, whose visual function was severely affected. The particularities of her genetic constellation regarding the retinal circulation are also discussed. The patient developed a central retinal artery occlusion in the right eye during pregnancy in 2010, which led to an extended hematological workup that revealed presence of MTHFR C677T and MTHFR A1298C heterozygote mutations. The screening for myeloproliferative disorders showed JAK2 V617F gene mutation. Test results confirmed the diagnosis of thrombophilia and essential thrombocythemia and she was recommended permanent treatment with low molecular weight heparin, platelet antiaggregant, peripheral vasodilator and neuroprotectors. Despite the treatment, the patient developed central retinal vein occlusion in the fellow eye 8 years after the first thromboembolic event. The visual acuity for the right eye (0.9 logMAR) remained poor and the visual acuity for the left eye recovered completely (from 0.3 logMAR to 0 logMAR). However, new retinal artery or vein occlusions could occur in the future and there is also a risk of thrombosis in other areas, such as cerebral, pulmonary or renal, due to the general coagulability imbalance.

Next Generation Sequencing in MPNs. Lessons from the Past and Prospects for Use as Predictors of Prognosis and Treatment Responses

The myeloproliferative neoplasms (MPNs) are acquired hematological stem cell neoplasms characterized by driver mutations in JAK2, CALR, or MPL. Additive mutations may appear in predominantly epigenetic regulator, RNA splicing and signaling pathway genes. These molecular mutations are a hallmark of diagnostic, prognostic, and therapeutic assessment in patients with MPNs. Over the past decade, next generation sequencing (NGS) has identified multiple somatic mutations in MPNs and has contributed substantially to our understanding of the disease pathogenesis highlighting the role of clonal evolution in disease progression. In addition, disease prognostication has expanded from encompassing only clinical decision making to include genomics in prognostic scoring systems. Taking into account the decreasing costs and increasing speed and availability of high throughput technologies, the integration of NGS into a diagnostic, prognostic and therapeutic pipeline is within reach. In this review, these aspects will be discussed highlighting their role regarding disease outcome and treatment modalities in patients with MPNs.

Cytoreductive treatment in patients with CALR-mutated essential thrombocythaemia: a study comparing indications and efficacy among genotypes from the Spanish Registry of Essential Thrombocythaemia

The present study assessed the criteria for initiating cytoreduction and response to conventional therapies in 1446 patients with essential thrombocythemia (ET), 267 (17%) of which were CALR-mutated. In low risk patients, time from diagnosis to cytoreduction was shorter in CALR-positive than in the other genotypes (2·8, 3·2, 7·4 and 12·5 years for CALR, MPL, JAK2V617F and TN, respectively, P < 0·0001). A total of 1104 (76%) patients received cytoreductive treatment with hydroxycarbamide (HC) (n = 977), anagrelide (n = 113), or others (n = 14). The estimated cumulative rates of complete haematological response (CR) at 12 months were 40 % and 67% in CALR and JAK2V617F genotypes, respectively. Median time to CR was 192 days for JAK2V617F, 343 for TN, 433 for MPL, and 705 for CALR genotypes (P < 0·0001). Duration of CR was shorter in CALR-mutated ET than in the remaining patients (P = 0·003). In CALR-positive patients, HC and anagrelide had similar efficacy in terms of response rates and duration. CALR-mutated patients developed resistance/intolerance to HC more frequently (5%, 23%, 27% and 15% for JAK2V617F, CALR, MPL and TN, respectively; P < 0·0001). In conclusion, conventional cytoreductive agents are less effective in CALR-mutated ET, highlighting the need for new treatment modalities and redefinition of haematologic targets for patients with this genotype.

Genomic heterogeneity in myeloproliferative neoplasms and applications to clinical practice

The myeloproliferative neoplasms (MPN) polycythaemia vera, essential thrombocythaemia and primary myelofibrosis are chronic myeloid disorders associated most often with mutations in JAK2, MPL and CALR, and in some patients with additional acquired genomic lesions. Whilst the molecular mechanisms downstream of these mutations are now clearer, it is apparent that clinical phenotype in MPN is a product of complex interactions, acting between individual mutations, between disease subclones, and between the tumour and background host factors. In this review we first discuss MPN phenotypic driver mutations and the factors that interact with them to influence phenotype. We consider the importance of ongoing studies of clonal haematopoiesis, which may inform a better understanding of why MPN develop in specific individuals. We then consider how best to deploy genomic testing in a clinical environment and the challenges as well as opportunities that may arise from more routine, comprehensive genomic analysis of patients with MPN.

Different impact of calreticulin mutations on human hematopoiesis in myeloproliferative neoplasms

Mutations of calreticulin (CALRm) define a subtype of myeloproliferative neoplasms (MPN). We studied the biological and genetic features of CALR-mutated essential thrombocythemia and myelofibrosis patients. In most cases, CALRm were found in granulocytes, monocytes, B and NK cells, but also in T cells. However, the type 1 CALRm spreads more easily than the type 2 CALRm in lymphoid cells. The CALRm were also associated with an early clonal dominance at the level of hematopoietic stem and progenitor cells (HSPC) with no significant increase during granulo/monocytic differentiation in most cases. Moreover, we found that half of type 2 CALRm patients harbors some homozygous progenitors. Those patients were associated with a higher clonal dominance during granulo/monocytic differentiation than patients with only heterozygous type 2 CALRm progenitors. When associated mutations were present, CALRm were the first genetic event suggesting that they are both the initiating and phenotypic event. In blood, type 1 CALRm led to a greater increased number of all types of progenitors compared with the type 2 CALRm. However, both types of CALRm induced an increase in megakaryocytic progenitors associated with a ruxolitinib-sensitive independent growth and with a mild constitutive signaling in megakaryocytes. At the transcriptional level, type 1 CALRm seems to deregulate more pathways than the type 2 CALRm in megakaryocytes. Altogether, our results show that CALRm modify both the HSPC and megakaryocyte biology with a stronger effect for type 1 than for type 2 CALRm.

Diagnosis of exon 12-positive polycythemia vera rescued by NGS

A JAK2V617F-negative polycythemia associated with low serum epo needs to be tested for an exon 12 JAK2 mutation. When negative, due to potential serious complications in PV, a next generation sequencing is necessary to rule out false negative results.

Eryptosis in polycythemia vera and essential thrombocythemia*

Aim: Polycythemia vera (PV) and essential thrombocythemia (ET) are Philadelphia–negative myeloproliferative neoplasms with documented apoptosis impairment at the level of hematopoietic stem cell. However, so far no study has evaluated apoptosis of circulating blood neoplastic cells, including the suicidal death of erythrocytes – eryptosis. Material/Methods: Erythrocytes from 61 patients (24 PV and 37 ET) naïve to and treated with hydroxyurea (HU) and 13 healthy individuals were analysed using flow cytometry to quantify phosphatidylserine (PS) externalization from Annexin-V-binding, calpain activity from 7-amino-4-chloromethylcoumarin (CMAC)-fluorescence, cell volume from forward scattered light (FSC) and cell shape from side scattered light (SSC). Results: Significantly increased levels of calpain activity and PS exposure were observed in both ET and PV naïve patients, indicating enhanced eryptosis. Among HU-treated patients, a significant increase in calpain activity in the ET group and a decrease in the PV group were observed compared to patients without cytoreductive therapy. Among PV patients, FSC was substantially higher in the HU-treated group than in the naïve group, whereas no significant differences were found between HU-treated and HU-naïve groups of ET patients. Conclusions: The enhanced eryptosis in ET and PV patients may be a form of systemic compensation of the pathological bone marrow overproduction of erythrocytes. HU, the basic cytoreductive drug used in ET and PV, may affect eryptosis in PV and ET in different ways depending on disease. The JAK2V617F mutation was not observed to have any effect on eryptosis in ET.

JAK2 mutation-positive polycythaemia vera associated with IgA vasculitis and nephrotic syndrome: a case report

We report a case of polycythaemia vera (PV) associated with IgA vasculitis. A 45-year-old man was admitted for evaluation of abdominal pain and palpable purpura. IgA vasculitis was diagnosed, and oral prednisolone therapy (30 mg/day) was initiated. On day 6, the patient developed left hemiparesis, and magnetic resonance imaging revealed acute cerebral infarction. Bone marrow biopsy results and the identification of a Janus kinase 2 (JAK2) mutation led to the diagnosis of PV. Despite steroid therapy, urine protein levels increased to 15 g/g・Cre. Renal biopsy demonstrated mild mesangial proliferation with IgA deposits, but immunosuppressive therapy was partially effective. This case suggests that PV can be a complication of IgA vasculitis and that preventive measures for thrombosis should be taken in such cases.

[Thrombosis and platelet dysfunction in myeloproliferative neoplasms]

Myeloproliferative neoplasms are acquired hematological malignancies, mainly affecting the adult and whose morbidity and mortality stems from haemostasis disorders. The most frequently encountered complications include thrombosis, affecting preferentially the arterial territory, but also atypical locations such as splanchnic vein thrombosis. The pathophysiology of these thromboses is complex and involves different actors: blood cells, endothelium and flow conditions. Numerous studies have been conducted to identify risk factors for thrombosis. To date, only two risk factors have been validated through prospective studies (age over 60 years old, history of thrombotic events) and allow classification of patients as "low risk" and "high risk" as the basis for current treatment recommendations. Haemorrhagic manifestations, less frequent than thrombosis, are mainly related to an alteration of primary haemostasis and are therefore manifested by mucocutaneous bleeding. In these patients, platelet dysfunctions and/or acquired Willebrand syndromes can be found. The pathophysiology of thrombosis and platelet dysfunction during myeloproliferative neoplasms remains to date partially unknown. In this review, we offer to focus on physiopathological mechanisms as well as the latest advances in their understanding.