Polycythemia vera

Polycythemia vera (PV) is mainly characterized by erythrocytosis, thrombotic and hemorrhagic predisposition, a variety of symptoms, and cumulative risks of fibrotic progression and/or leukemic evolution over time. The diagnosis is made based on the 2016 WHO criteria. The treatment of PV focuses on rapidly reducing the erythrocyte mass, either by means of phlebotomies or with cytoreductive treatment, and the reduction of thrombotic risk by correcting cardiovascular risk factors and the use of platelet antiaggregants.

Risks in invasive procedures

Patients with myeloproliferative neoplasms have an increased risk of thrombosis and bleeding. This risk must be identified, as well as individualizing the therapeutic strategy before invasive procedures; adequate cytoreduction reduces the risk of complications.

Patients with MPNs and retinal drusen show signs of complement system dysregulation and a high degree of chronic low-grade inflammation

BACKGROUND

The hematopoietic stem cell disorders, myeloproliferative neoplasms (MPNs), are characterised by chronic low-grade inflammation (CLI). Recently, we showed that patients with MPNs have an increased prevalence of drusen and age-related macular degeneration (AMD), and drusen prevalence seemed associated with higher CLI. Studying MPNs may reveal more about drusen pathophysiology. This study investigated CLI further by measuring cytokine levels and complement system markers, comparing these between patients with MPNs and AMD.

METHODS

This cross-sectional study, between July 2018 and November 2020 conducted at Zealand University Hospital (ZUH) - Roskilde, Denmark, included 29 patients with neovascular AMD (nAMD), 28 with intermediate-stage AMD (iAMD), 62 with MPNs (35 with drusen - MPNd and 27 with healthy retinas - MPNn). With flow cytometry, we measured complement-regulatory-proteins (Cregs). With immunoassays, we investigated cytokine levels combined into a summary-inflammation-score (SIS).

FINDINGS

The MPNd and nAMD groups had similar SIS, significantly higher than the MPNn and iAMD groups. Additionally, we found SIS to increase over the MPN biological continuum from early cancer stage, essential thrombocytaemia (ET), over polycythaemia vera (PV) to the late-stage primary myelofibrosis (PMF). MPNs showed signs of complement dysregulation, with Cregs expression lower in PV than ET and PMF and even lower in PV patients with drusen.

INTERPRETATION

This study suggests that MPNd have a higher CLI than MPNn and may indicate systemic CLI to play a greater part in, and even initiate drusen formation. We suggest using MPNs as a "Human Inflammation Model" of drusen development. The CLI in MPNs elicits drusen formation, triggering more CLI creating a vicious cycle, increasing the risk of developing AMD.

FUNDING

Fight for Sight, Denmark, and Region Zealand's research promotion fund.

Advances in polycythemia vera and lessons for acute leukemia

The myeloproliferative neoplasms (MPN), polycythemia vera (PV), essential thrombocytosis and primary myelofibrosis, are an unusual group of myeloid neoplasms, which arise in a pluripotent hematopoietic stem cell (HSC) due to gain of function driver mutations in the JAK2, CALR and MPL genes that constitutively activate JAK2, the cognate tyrosine kinase of the type 1 hematopoietic growth factor (HGF) receptors. PV is the ultimate phenotypic expression of constitutive JAK2 activation since it alone of the three MPN is characterized by overproduction of normal red cells, white cells and platelets. Paradoxically, however, although PV is a panmyelopathy involving myeloid, erythroid and megakaryocytic progenitor cells, pluripotent HSC only express a single type of HGF receptor, the thrombopoietin receptor, MPL. In this review, the basis for how a pluripotent HSC with one type of HGF can give rise to three separate types of myeloid cells will be explained and it will be demonstrated that PV is actually a hormone-sensitive disorder, characterized by elevated thrombopoietin levels. Finally, it will be shown that the most common form of acute leukemia in PV is due to the inappropriate use of chemotherapy, including hydroxyurea, which facilitates expansion of DNA-damaged, mutated HSC at the expense of their normal counterparts.

Can molecular insights guide treatment of AML evolved from MPNs?

Leukemic transformation of myeloproliferative neoplasms (MPNs) is associated with dismal outcomes. The genetic complexity of leukemic transformation of MPNs is being deciphered and will likely result in targeted therapy approaches. Ongoing trials are investigating the efficacy of emerging treatments for this high-risk patient population. This review has outlined recent progress in the understanding and treatment of leukemia arising from MPNs.

[Health-related quality of life and its associated variables in Chinese patients with Philadelphia-negative myeloproliferative neoplasms]

Objectives: To explore health-related quality of life (HRQoL) and identify its associated variables in Chinese patients with Philadelphia-negative myeloproliferative neoplasms (MPNs) . Methods: In this cross-sectional study, anonymous questionnaires were distributed to adult patients with MPNs to assess symptom burden measured by MPN-10 and HRQoL measured by Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) and the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) . Results: The data from 1405 respondents with MPNs, including 645 (45.9%) with essential thrombocythemia (ET) , 297 (21.1%) with polycythemia vera (PV) , and 463 (33.0%) with myelofibrosis (MF) , were analyzed. 646 (46.0%) respondents were male. The median age was 56 (range, 18-99) years. The mean MPN-10 scores were 13.0±12.7, 15.0±14.7, and 21.0±16.6 (P<0.001) , and the physical component summary (PCS) and mental component summary (MCS) scores were 48.0±8.5, 47.0±9.0, and 42.0±10.0 (P<0.001) and 51.0±11.0, 50.0±10.8, and 49.0±11.1 (P=0.002) for respondents with ET, PV, and MF, respectively. Respondents with MF reported the lowest score of physical functioning, role functioning, emotional functioning, cognitive functioning, social function, and global health status (all P<0.01) and the highest score of fatigue, pain, dyspnea, appetite loss, diarrhea, and financial problems (all P<0.05) in EORTC QLQ-C30. Multivariate analyses revealed that higher MPN-10 scores were significantly associated with lower PCS (-0.220 to -0.277, P<0.001) and MCS (-0.244 to -0.329, P<0.001) scores; increasing age (-1.923 to -4.869; all P<0.05) , lower PCS score. Additionally, comorbidity (ies) , symptom at diagnosis, splenomegaly, anemia, unknown driver gene, and higher annual out-of-pocket cost were significantly associated with lower PCS and/or MCS scores. However, age ≥ 60 years, urban household registration, concomitant medication, and receiving ruxolitinib therapy in respondents with MF were associated with higher MCS scores. Weak correlations were found between MPN-10 score (except the subscale of appetite loss and constipation) and EORTC QLQ-C30 score in majority of subscales in respondents with ET (|r| = 0.193-0.457, all P<0.001) , PV (|r| = 0.192-0.529, all P<0.01) , and MF (|r| = 0.180-0.488, all P<0.001) , respectively. Conclusions: HRQoL in patients with MPN was significantly reduced, especially in patients with MF. Sociodemographic and clinical variables were significantly associated with the HRQoL in patients with MPNs.

The Classification of Myeloproliferative Neoplasms: Rationale, Historical Background and Future Perspectives with Focus on Unclassifiable Cases

Simple Summary

Myeloproliferative neoplasms (MPNs) are clonal hematological disorders, characterized by increased proliferation of the myeloid lineages in the bone marrow. Since their original recognition by William Damashek in 1951, MPNs have been extensively investigated at a clinical-pathological and molecular level. This prompted a progressive refinement of their classification and diagnostic criteria. Uncertainties nonetheless remain in a small (yet consistent) subset of cases, characterized by unconventional and/or overlapping clinical-pathological features. Such cases (referred to as MPN, unclassifiable [MPN-U]) encompass a broad spectrum of entities, including early phase MPNs, terminal (i.e., fibrotic) MPNs, MPNs associated with inflammatory or neoplastic disorders, and poorly characterized MPNs with clinical-pathological mismatch or atypical molecular features. In this review, we discuss the rationale behind the classification and diagnostic criteria of MPNs, focusing on the still open issues concerning MPN-U.

Abstract

Myeloproliferative neoplasms (MPNs) are a heterogeneous group of clonal hematopoietic stem cell disorders, characterized by increased proliferation of one or more myeloid lineages in the bone marrow. The classification and diagnostic criteria of MPNs have undergone relevant changes over the years, reflecting the increased awareness on these conditions and a better understanding of their biological and clinical-pathological features. The current World Health Organization (WHO) Classification acknowledges four main sub-groups of MPNs: (i) Chronic Myeloid Leukemia; (ii) classical Philadelphia-negative MPNs (Polycythemia Vera; Essential Thrombocythemia; Primary Myelofibrosis); (iii) non-classical Philadelphia-negative MPNs (Chronic Neutrophilic Leukemia; Chronic Eosinophilic Leukemia); and (iv) MPNs, unclassifiable (MPN-U). The latter are currently defined as MPNs with clinical-pathological findings not fulfilling the diagnostic criteria for any other entity. The MPN-U spectrum traditionally encompasses early phase MPNs, terminal (i.e., advanced fibrotic) MPNs, and cases associated with inflammatory or neoplastic disorders that obscure the clinical-histological picture. Several lines of evidence and clinical practice suggest the existence of additional myeloid neoplasms that may expand the spectrum of MPN-U. To gain insight into such disorders, this review addresses the history of MPN classification, the evolution of their diagnostic criteria and the complex clinical-pathological and biological features of MPN-U.

Bone marrow microenvironment of MPN cells

In this chapter, we will discuss the current knowledge concerning the alterations of the cellular components in the bone marrow niche in Myeloproliferative Neoplasms (MPNs), highlighting the central role of the megakaryocytes in MPN progression, and the extracellular matrix components characterizing the fibrotic bone marrow.

Hematocrit to hemoglobin ratio as a prognostic marker in polycythemia vera

BACKGROUND

The hematocrit to hemoglobin ratio (HHR) is frequently used in everyday practice to measure hemoconcentration; however, clinical associations of HHR in the context of polycythemia vera (PV) have not been investigated so far.

PATIENTS AND METHODS

We retrospectively assessed HHR at the time of diagnosis in 107 PV and 40 secondary polycythemia (SP) patients from three community hospitals.

RESULTS

Median HHR was higher in PV than in SP patients (3.131 vs. 2.975, p = 0.041). Among PV patients, higher HHR correlated with splenomegaly, higher total leukocyte and absolute granulocyte counts, higher red blood cell counts, lower hemoglobin, higher red blood cell distribution width, lower mean corpuscular hemoglobin and lower ferritin levels, whereas in SP patients higher HHR correlated with older age, female sex and lower hemoglobin (p < 0.050 for all analyses). Using the receiver operating curve analysis-defined cut-off points, higher HHR in PV was associated with a shorter time to thrombosis (hazard ratio-HR 5.20, p = 0.022) independently of high-risk disease status (HR 4.48, p = 0.034) and shorter overall survival (HR 6.69, p = 0.009) independently of leukocytosis (HR 4.48, P = 0.034) and the absence of aspirin use (HR 15.53, p < 0.001).

CONCLUSION

Higher HHR may represent iron deficiency and a stronger clonal myeloproliferation in PV and could provide additional prognostic information to the classical risk assessment.

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

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

Transcriptional configurations of myeloproliferative neoplasms

Myeloproliferative neoplasms (MPNs) is an umbrella term for several heterogenous diseases, which are characterized by their stem cell origin, clonal hematopoiesis and increase of blood cells of the myeloid lineage. The focus will be on BCR-ABL1 negative MPNs, polycythemia vera (PV), primary myelofibrosis (PMF), essential thrombocythemia (ET). Seminal findings in the field of MPN were driven by genomic analysis, focusing on dissecting genomic changes MPN patients. This led to identification of major MPN driver genes, JAK2, MPL and CALR. Transcriptomic analysis promises to bridge the gap between genetic and phenotypic characterization of each patient's tumor and with the advent of single cell sequencing even for each MPN cancer cell. This review will focus on efforts to mine the bulk transcriptome of MPN patients, including analysis of fusion genes and splicing alterations which can be addressed with RNA-seq technologies. Furthermore, this paper aims to review recent endeavors to elucidate tumor heterogeneity in MPN hematopoietic stem and progenitor cells using single cell technologies. Finally, it will highlight current shortcoming and future applications to advance the field in MPN biology and improve patient diagnostics using RNA-based assays.

JAK2 p.(V617F) mutation in Tunisian myeloproliferative neoplasms and its genotype-phenotype correlation

Myeloproliferative neoplasms (MPNs) comprise polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). The relationship between JAK2 p.(V617F) mutation and MPNs was first described in 2005. The purpose of this study was to determine the prevalence of JAK2 p.(V617F) mutation in Tunisian patients assessed for MPNs and try to set a genotype-phenotype correlation. A retrospective study was conducted between January 2015 and April 2019. We collected the clinical data of all patients with MPNs suspicion or atypical splanchnic vein thrombosis (SVT). JAK2 p.(V617F) mutation was detected by allele specific real-time quantitative fluorescence PCR (AS-qPCR). We gathered 974 patients who underwent molecular analysis, 55.5% of them were male and 44.5% were female. The median age of all studied patients was 56 years. JAK2 p.(V617F) was found in 349 (35.8%) of total enrolled cases. It was reported in 44%, 37%, 29% and 25% of all patients diagnosed as having respectively ET, PV, PMF and atypical SVT. JAK2 p.(V617F) was negative in 62.2% of patients addressed for suspicion of PV. There was a significant positive correlation between the JAK2 p.(V617F) mutation status, age, gender, white blood cell counts and platelet counts. To our best knowledge, this is the first vast investigation of JAK2 p.(V617F) variant in Tunisia and North Africa with the lowest mutation rate in entire cohort and MPNs subgroups, underlying a specific presentation of this mutation. It is considered as an essential marker of MPNs’ diagnosis and prognosis and is associated with differences in the phenotype of these disorders, helpful for the follow-up of these patients.

Philadelphia-Negative Myeloproliferative Neoplasms Around the COVID-19 Pandemic

PURPOSE OF REVIEW

Coronavirus disease 2019 (COVID-19) is associated with a high rate of respiratory failure, thromboembolism, bleeding, and death. Patients with myeloproliferative neoplasms (MPNs) are prone to both thrombosis and bleeding, calling for special care during COVID-19. We reviewed the clinical features of MPN patients with COVID-19, suggesting guidance for treatment.

RECENT FINDINGS

One study by the European LeukemiaNet collected 175 MPN patients with COVID-19 during the first wave of the pandemic, from February to May 2020. Patients with primary myelofibrosis (PMF) were at higher risk of mortality (48%) in comparison with essential thrombocythemia (ET) (25%) and polycythemia vera (19%); the risk of death was higher in those patients who abruptly discontinued ruxolitinib. In patients followed at home, in regular wards, or in ICU, the thrombosis rate was 1.0%, 2.8%, and 18.4%, respectively. Independent risk factors for thrombosis were ET phenotype, transfer to ICU, and neutrophil/lymphocyte ratio; major bleeding occurred in 4.3% of patients, particularly those with PMF. MPN patients with non-severe COVID-19 treated at home should continue their primary or secondary antithrombotic prophylaxis with aspirin or oral anticoagulants. In the case of hospitalization, patients assuming aspirin should add low molecular weight heparin (LMWH) at standard doses. In contrast, LMWH at intermediate/therapeutic doses should replace oral anticoagulants prescribed for atrial fibrillation or previous venous thromboembolism. Intermediate/high doses of LMWH can also be considered in ICU patients with ET, particularly in the case of a rapid decline in the number of platelets and progressive respiratory failure.

Targets in MPNs and potential therapeutics

Philadelphia-negative classical Myeloproliferative Neoplasms (MPNs), including Polycythemia Vera (PV), Essential Thrombocythemia (ET) and Primary Myelofibrosis (PMF), are clonal hemopathies that emerge in the hematopoietic stem cell (HSC) compartment. MPN driver mutations are restricted to specific exons (14 and 12) of Janus kinase 2 (JAK2), thrombopoietin receptor (MPL/TPOR) and calreticulin (CALR) genes, are involved directly in clonal myeloproliferation and generate the MPN phenotype. As a result, an increased number of fully functional erythrocytes, platelets and leukocytes is observed in the peripheral blood. Nevertheless, the complexity and heterogeneity of MPN clinical phenotypes cannot be solely explained by the type of driver mutation. Other factors, such as additional somatic mutations affecting epigenetic regulators or spliceosomes components, mutant allele burdens and modifiers of signaling by driver mutants, clonal architecture and the order of mutation acquisition, signaling events that occur downstream of a driver mutation, the presence of specific germ-line variants, the interaction of the neoplastic clone with bone marrow microenvironment and chronic inflammation, all can modulate the disease phenotype, influence the MPN clinical course and therefore, might be useful therapeutic targets.

Living with an MPN in Ireland: patients' and caregivers' perspectives

Myeloproliferative neoplasms (MPNs) are associated with a high disease burden, reduced quality of life and shortened survival. The aim of this questionnaire was to gain patients' and caregivers' perspectives on the impact of living with an MPN in the Republic of Ireland. An Irish adaptation of the 'Global MPN Landmark survey' was conducted. Fifty-one patients and 44 caregivers completed the questionnaire. Patients reported a wide variety of symptoms at the time of questionnaire completion; fatigue, bone pain and pruritus being most frequently reported. Approximately one-third of respondents from each of the groups (patients and caregivers) reported a negative impact of MPNs on their emotional wellbeing and daily lives. The study findings revealed that, despite treatment, symptom burden remains high, and several unmet needs exist, including educational, emotional and peer group support. Interventions that focus on reducing symptom burden and addressing these unmet needs, may improve the quality of life for patients with MPNs and their caregivers.

Spatial disparities in the reported incidence and survival of myeloproliferative neoplasms in Australia

Myeloproliferative neoplasms (MPNs) are an uncommon group of blood cancers that, if untreated, result in an increased risk of haemorrhagic event or thrombosis. Unlike other cancer types, diagnosis of MPNs requires a combination of microscopic, clinical and genetic evidence, which provide unique challenges given the typical notification processes of cancer registries. This, and the relatively recent advances in diagnosis and revision of the World Health Organization diagnostic criteria, may result in under-diagnosis or under-reporting of MPNs. We used population-based cancer registry data from the Australian Cancer Database and modelled the incidence and survival of MPNs between 2007 and 2016 using generalised linear models and Bayesian spatial Leroux models. Substantial evidence was found of spatial heterogeneity in the incidence of MPNs and significant differences in incidence and survival by state or territory. States with lower incidence tended to have poorer survival, suggesting that some less severe cases may not be diagnosed or notified to the registries in those states. Population rates of genetic testing and percentages of records diagnosed using bone marrow biopsies did not explain the differences in incidence by state and territory. It is important to determine the key drivers of these geographical patterns, including the need to standardise diagnosis and reporting of MPNs.

[Clinical impact of gene mutations on myeloproliferative neoplasms in Japan]

Myeloproliferative neoplasms (MPN) are caused by somatic mutations in hematopoietic stem/progenitor cells and result in excessive increase in the blood cell mass in the peripheral blood and/or fibrosis in the bone marrow. JAK2, CALR, and MPL mutations are well-known driver mutations of MPN and are widely applied as diagnostic markers of MPN. Moreover, several studies using massive parallel sequencing technologies have shown that mutations in ASXL1, EZH2, SRSF2, and IDH1/2 affect the prognosis of overt primary myelofibrosis and have further clarified that the mutation order may influence the MPN phenotype. More recently, our group identified that CREB3L1 mRNA was overexpressed in a platelet- and megakaryocyte-specific manner in driver mutation positive MPN and that the quantitation of this gene expression can be used as a diagnostic marker for MPN. In this educational lecture, we discuss the clinical impacts of the mutations frequently identified in MPN patients.

Myeloproliferative neoplasm questionnaire: assessing patient disease knowledge in the modern digital information era

There is growing Internet and social media use among patients with rare blood cancers, notably myeloproliferative neoplasms (MPNs). A 38-item online questionnaire was developed to assess patients' (n = 983) disease understanding and use of online resources regarding MPN. Many responders (74%) reported unawareness of additional mutations beyond their primary molecular marker(s); 32% were unsure of their prognostic risk stratification. Additionally, 89% reported using online resources (Facebook (61%); Google/Google+ (42%); YouTube (34%); blogs (26%); Twitter (5%)) to seek information about MPN. Despite this, results showed many gaps in patients' basic disease knowledge. Our findings suggest an important difference in social media habits between physicians and patients: physicians are rapidly adopting Twitter as their preferred medium for sharing medical knowledge; however, patients often prefer other social mediums. Educational campaigns should be designed in more personalized ways, aiming to fit a variety of online platforms to maximize reach and impact for patients with MPN.

Pediatric Myeloproliferative Neoplasms

Myeloproliferative neoplasms can present early in life and may present a diagnostic challenge. Very few studies have focused on the diagnosis, prognosis, and therapy for pediatric myeloproliferative neoplasms. This article focuses on chronic myeloid leukemia, essential thrombocythemia, polycythemia vera, and primary myelofibrosis in children.

Impact of Calreticulin and Its Mutants on Endoplasmic Reticulum Function in Health and Disease

The endoplasmic reticulum (ER) performs key cellular functions including protein synthesis, lipid metabolism and signaling. While these functions are spatially isolated in structurally distinct regions of the ER, there is cross-talk between the pathways. One vital player that is involved in ER function is the ER-resident protein calreticulin (CALR). It is a calcium ion-dependent lectin chaperone that primarily assists in glycoprotein synthesis in the ER as part of the protein quality control machinery. CALR also buffers calcium ion release and mediates other glycan-independent protein interactions. Mutations in CALR have been reported in a subset of chronic blood tumors called myeloproliferative neoplasms. The mutations consist of insertions or deletions in the CALR gene that all cause a + 1 bp shift in the reading frame and lead to a dramatic alteration of the amino acid sequence of the C-terminal domain of CALR. This alters CALR function and affects cell homeostasis. This chapter will discuss how CALR and mutant CALR affect ER health and disease.

Direct oral anticoagulants (DOAC) for prevention of recurrent arterial or venous thromboembolic events (ATE/VTE) in myeloproliferative neoplasms

In patients with BCR-ABL-negative myeloproliferative neoplasms (MPN), arterial or venous thromboembolic events (ATE/VTE) are a major burden. In order to control these complications, vitamin K antagonists (VKA) are widely used. There is no robust evidence supporting the use of direct oral anticoagulants (DOAC) in MPN patients. We therefore compared the efficacy and safety of both anticoagulants in 71 cases from a cohort of 782 MPN patients. Seventy-one of 782 MPN patients (9.1%) had ATE/VTE with nine ATE (12.7%) and 62 VTE (87.3%). Forty-five of 71 ATE/VTE (63.4%) were treated with VKA and 26 (36.6%) with DOAC. The duration of anticoagulation therapy (p = 0.984), the number of patients receiving additional aspirin (p = 1.0), and the proportion of patients receiving cytoreductive therapy (p = 0.807) did not differ significantly between the VKA and DOAC groups. During anticoagulation therapy, significantly more relapses occurred under VKA (n = 16) compared to DOAC treatment (n = 0, p = 0.0003). However, during the entire observation period of median 3.2 years (0.1-20.4), ATE/VTE relapse-free survival (p = 0.2) did not differ significantly between the two anticoagulants. For all bleeding events (p = 0.516) or major bleeding (p = 1.0), no significant differences were observed between VKA and DOAC. In our experience, the use of DOAC was as effective and safe as VKA, possibly even potentially beneficial with a lower number of recurrences and no increased risk for bleedings. However, further and larger studies are required before DOAC can be routinely used in MPN patients.

[Perspectives on a new therapeutic approach for myeloproliferative neoplasms]

After the discovery of driver mutations for myeloproliferative neoplasms (MPN), treatment approach for the disease has achieved tremendous progress. Ruxolitinib, a JAK inhibitor, is now widely used for both patients with myelofibrosis and polycythemia vera in several countries, including Japan. Fedratinib, another JAK inhibitor, has been recently approved in the United States. One of the biggest limitations of treatment with JAK inhibitors is the relatively small proportion of patients who achieve a complete molecular response. Furthermore, most of the patients with myelofibrosis had to discontinue the treatment due to drug-related adverse events or disease progression. Therefore, MPN treatment is still at an early and challenging stage, thereby highlighting the urgent need for establishment of a new and more effective therapeutic strategy. One of the promising candidates for MPN treatment is the use of interferons. Modern forms of interferons demonstrate not only a good hematological response but also a deep molecular response, eradicating abnormal MPN clones harboring driver mutations. A number of new agents targeting molecules outside of the JAK-STAT pathway, PI3kinase, NF-kB, or Bcl-2 family of anti-apoptotic proteins are also being considered and tested in clinical studies as single-agent therapies or in combination with JAK inhibitors.

Molecular pathogenesis of the myeloproliferative neoplasms

The Philadelphia negative myeloproliferative neoplasms (MPN) compromise a heterogeneous group of clonal myeloid stem cell disorders comprising polycythaemia vera, essential thrombocythaemia and primary myelofibrosis. Despite distinct clinical entities, these disorders are linked by morphological similarities and propensity to thrombotic complications and leukaemic transformation. Current therapeutic options are limited in disease-modifying activity with a focus on the prevention of thrombus formation. Constitutive activation of the JAK/STAT signalling pathway is a hallmark of pathogenesis across the disease spectrum with driving mutations in JAK2, CALR and MPL identified in the majority of patients. Co-occurring somatic mutations in genes associated with epigenetic regulation, transcriptional control and splicing of RNA are variably but recurrently identified across the MPN disease spectrum, whilst epigenetic contributors to disease are increasingly recognised. The prognostic implications of one MPN diagnosis may significantly limit life expectancy, whilst another may have limited impact depending on the disease phenotype, genotype and other external factors. The genetic and clinical similarities and differences in these disorders have provided a unique opportunity to understand the relative contributions to MPN, myeloid and cancer biology generally from specific genetic and epigenetic changes. This review provides a comprehensive overview of the molecular pathophysiology of MPN exploring the role of driver mutations, co-occurring mutations, dysregulation of intrinsic cell signalling, epigenetic regulation and genetic predisposing factors highlighting important areas for future consideration.

MPL overexpression induces a high level of mutant-CALR/MPL complex: a novel mechanism of ruxolitinib resistance in myeloproliferative neoplasms with CALR mutations

Ruxolitinib (RUX), a JAK1/2-inhibitor, is effective for myeloproliferative neoplasm (MPN) with both JAK2V617 F and calreticulin (CALR) mutations. However, many MPN patients develop resistance to RUX. Although mechanisms of RUX-resistance in cells with JAK2V617 F have already been characterized, those in cells with CALR mutations remain to be elucidated. In this study, we established RUX-resistant human cell lines with CALR mutations and characterized mechanisms of RUX-resistance. Here, we found that RUX-resistant cells had high levels of MPL transcripts, overexpression of both MPL and JAK2, and increased phosphorylation of JAK2 and STAT5. We also found that mature MPL proteins were more stable in RUX-resistant cells. Knockdown of MPL in RUX-resistant cells by shRNAs decreased JAK/STAT signaling. Immunoprecipitation assays showed that binding of mutant CALR to MPL was increased in RUX-resistant cells. Reduction of mutated CALR decreased proliferation of the resistant cells. When resistant cells were cultured in the absence of RUX, the RUX-resistance was reversed, with reduction of the mutant-CALR/MPL complex. In conclusion, MPL overexpression induces higher levels of a mutant-CALR/MPL complex, which may cause RUX-resistance in cells with CALR mutations. This mechanism may be a new therapeutic target to overcome RUX-resistance.

Tobacco use in the Myeloproliferative neoplasms: symptom burden, patient opinions, and care

BACKGROUND

Patients with Philadelphia-negative Myeloproliferative Neoplasms (MPN) suffer from numerous symptoms and decreased quality of life. Smoking is associated with an increased symptom burden in several malignancies. The aim of this study was to analyze the association between smoking and MPN-related symptom burden and explore MPN patients' opinions on smoking.

METHODS

A total of 435 patients with MPN participated in a cross-sectional internet-based survey developed by the Mayo Clinic and the Myeloproliferative Neoplasm Quality of Life Group. Patients reported their demographics, disease characteristics, tobacco use, and opinions on tobacco use. In addition, MPN-related symptoms were reported via the validated 10-item version of the Myeloproliferative Neoplasms Symptom Assessment Form.

RESULTS

Current/former smokers reported worse fatigue (mean severity 5.6 vs. 5.0, p = 0.02) and inactivity (mean severity 4.0 vs. 3.4, p = 0.03) than never smokers. Moreover, current/former smokers more frequently experienced early satiety (68.5% vs. 58.3%, p = 0.03), inactivity (79.9% vs. 71.1%, p = 0.04), and concentration difficulties (82.1% vs. 73.1%, p = 0.04). Although not significant, a higher total symptom burden was observed for current/former smokers (mean 30.4 vs. 27.0, p = 0.07). Accordingly, overall quality of life was significantly better among never smokers than current/former smokers (mean 3.5 vs. 3.9, p = 0.03). Only 43.2% of the current/former smokers reported having discussed tobacco use with their physician, and 17.5% did not believe smoking increased the risk of thrombosis.

CONCLUSION

The current study suggests that smoking may be associated with increased prevalence and severity of MPN symptoms and underscores the need to enhance patient education and address tobacco use in the care of MPN patients.