Hydroxyurea compared with anagrelide in high-risk essential thrombocythemia

Aspirin use in essential thrombocythemia: Once-daily or twice-daily or not at all?

Asprin dosing strategy in low risk (young and JAK2 mutated without history of thrombosis) or very low risk (young JAK2 wild-type without history of thrombosis) essential thrombocythemia.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

SOHO State of the Art Updates and Next Questions | Diagnosis, Outcomes, and Management of Prefibrotic Myelofibrosis

Prefibrotic primary myelofibrosis (prefibrotic PMF) is a myeloproliferative neoplasm with distinct characteristics comprising histopathological and clinico-biological parameters. It is classified as a subtype of primary myelofibrosis. In clinical practice, it is essential to correctly distinguish prefibrotic PMF from essential thrombocythemia especially but also overt PMF besides other myeloid neoplasms. Risk stratification and survival outcomes for prefibrotic PMF are worse than that of ET but better than that of overt PMF. Rates of progression to overt PMF and blast phase disease are also higher for prefibrotic PMF than ET. In this review we first discuss the historical context to the evolution of prefibrotic PMF as an entity, its presenting features and diagnostic criteria. We emphasize the differences between prefibrotic PMF, ET, and overt PMF with regards to presenting features and disease outcomes including thrombohemorrhagic events and progression to fibrotic and blast phase disease. Next, we discuss the risk stratification models and contextualize these in the setting of clinical management. We share our view of personalizing treatment to address unique patient needs in the context of currently available management options. Lastly, we discuss areas of critical need in clinical research and speculate on the possibility of future disease course modifying therapies in prefibrotic PMF.

Myeloproliferative neoplasms in the adolescent and young adult population: A comprehensive review of the literature

Myeloproliferative neoplasms (MPN) are characterized by a clonal proliferation of myeloid lineage cells within the bone marrow. The classical BCR-ABL negative MPNs are comprised of polycythaemia vera, essential thrombocythaemia and primary myelofibrosis. Historically, the majority of MPNs are diagnosed in adults older than 60 years of age; however, in recent years, there has been recognition of MPNs in the adolescent and young adult (AYA) population. AYAs with MPN, typically defined as between the ages of 15 and 39 years old, may comprise up to 20% of patients diagnosed with MPN. They demonstrate unique patterns of driver mutations and thrombotic events and remain at risk for progression to more aggressive disease states. Given the likely long length of time they will live with their disease, there is a significant unmet need in identifying well-tolerated and effective treatment options for these patients, particularly with the advent of disease modification. In this review, we provide a comprehensive overview of the clinical features, disease course and management of AYA patients with MPN and, in doing so, highlight key characteristics that distinguish them from their older counterparts.

Initial Low-Dose Hydroxyurea and Anagrelide Combination in Essential Thrombocythemia: Comparable Response with Lower Toxicity

Background and Objectives: Essential thrombocythemia (ET) is a myeloproliferative neoplasm that overproduces platelets and is associated with life-threatening thrombosis. Medical cytoreduction either with hydroxyurea (HU) or anagrelide (AG) is widely used, but drug intolerance or resistance are major concerns. Low-dose combination of HU and AG as an alternative strategy has been explored in various studies. It showed comparable response with acceptable toxicity in second-line settings for patients who experienced side effects from prior monotherapy. In this study, we evaluated the efficacy and safety of upfront combination for ET patients. Materials and Methods: From January 2018 to June 2022, a total of 241 ET patients with intermediate to high risk were enrolled. We identified 21 patients with initial drug combinations and compared treatment outcomes and adverse events (AEs) between combination and monotherapy groups. Results: The median age was 62 years old (range, 26-87) and median platelet count was 912 × 109/L (range, 520-1720). Overall treatment response did not exhibit significant differences between the groups, although there was a trend towards a lower response rate in patients treated with AG alone at 3 months post-treatment (AG + HU, 85.7% vs. AG alone, 75.4%, p = 0.068). AEs of any grade occurred in 52.3% of the combination group, 44.3% of the HU monotherapy group, and 43.4% of the AG single group, respectively. Of note was that the HU plus AG combination group suffered a lower incidence of grade 3-4 AEs compared to the other two groups, with statistical significance (p = 0.008 for HU monotherapy vs. combination therapy and p < 0.01 for AG monotherapy vs. combination therapy). Conclusions: Our findings demonstrated that the upfront low-dose combination approach showed feasible clinical outcomes with significantly lower severe AEs compared to conventional monotherapy. These results may offer valuable insights to clinicians for future prospective investigations.

Cancer-associated thrombosis in hematologic malignancies

Patients with hematologic malignancies are often complicated not only by severe bleeding due to thrombocytopenia and disseminated intravascular coagulation but also by thromboembolic events, just like in patients with solid cancers, and these events can negatively impact patient outcomes. Nevertheless, the prevention and treatment of cancer-associated thrombosis (CAT) in hematologic malignancies has not been adequately investigated due to the limited size, heterogeneity, and unique pathophysiology of the patient population. This article summarizes the current understanding, risk factors, prediction models, and optimal prevention and treatment strategies of CAT in hematologic malignancies on a disease-by-disease basis, including acute leukemia, lymphoma, myeloma, and myeloproliferative neoplasms. Specific considerations of novel molecular targeted therapeutics introduced in recent years, such as immunomodulatory drugs and tyrosine kinase inhibitors, are also discussed based on the latest clinical trials.

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

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

Reactive Thrombocytosis: A Bizarre Consequence of Splenectomy

Platelets are blood components produced in the bone marrow and are essential in forming blood clots. Thrombocytosis refers to a condition that causes the excess production of platelets in the body. When it develops as a reaction to an infection, trauma, or surgery, it is known as secondary or reactive thrombocytosis. Although thrombocytosis is typically a self-limiting disorder, it can frequently result in hemorrhagic or thrombotic events. Extreme thrombocytosis may trigger thrombotic events. Therefore, clinicians must be aware of the complications of thrombocytosis. In this case report, a 35-year-old female, known to have portal hypertension and Budd-Chiari syndrome, presented with complaints of weakness and tingling in her hands persisting for eight days. She disclosed that she had undergone an elective splenectomy as part of her management for portal hypertension and Budd-Chiari syndrome eight days prior.

Essential thrombocythemia: 2024 update on diagnosis, risk stratification, and management

OVERVIEW

Essential thrombocythemia is a Janus kinase 2 (JAK2) mutation-prevalent myeloproliferative neoplasm characterized by clonal thrombocytosis; clinical course is often indolent but might be interrupted by thrombotic or hemorrhagic complications, microcirculatory symptoms (e.g., headaches, lightheadedness, and acral paresthesias), and, less frequently, by disease transformation into myelofibrosis (MF) or acute myeloid leukemia.

DIAGNOSIS

In addition to thrombocytosis (platelets ≥450 × 109 /L), formal diagnosis requires the exclusion of other myeloid neoplasms, including prefibrotic MF, polycythemia vera, chronic myeloid leukemia, and myelodysplastic syndromes with ring sideroblasts and thrombocytosis. Bone marrow morphology typically shows increased number of mature-appearing megakaryocytes distributed in loose clusters.

GENETICS

Approximately 80% of patients express myeloproliferative neoplasm driver mutations (JAK2, CALR, MPL), in a mutually exclusive manner; in addition, about 50% harbor other mutations, the most frequent being TET2 (9%-11%), ASXL1 (7%-20%), DNMT3A (7%), and SF3B1 (5%). Abnormal karyotype is seen in <10% of patients and includes +9/20q-/13q-.

SURVIVAL AND PROGNOSIS

Life expectancy is less than that of the control population. Median survival is approximately 18 years but exceeds >35 years in younger patients. The triple A survival risk model, based on Age, Absolute neutrophil count, and Absolute lymphocyte count, effectively delineates high-, intermediate-1-, intermediate-2-, and low-risk disease with corresponding median survivals of 8, 14, 21, and 47 years.

RISK FACTORS FOR THROMBOSIS

Four risk categories are considered: very low (age ≤60 years, no thrombosis history, JAK2 wild-type), low (same as very low but JAK2 mutation present), intermediate (same as low but age >60 years), and high (thrombosis history or age >60 years with JAK2 mutation).

MUTATIONS AND PROGNOSIS

MPL and CALR-1 mutations have been associated with increased risk of MF transformation; spliceosome with inferior overall and MF-free survival; TP53 with leukemic transformation, and JAK2V617F with thrombosis. Leukemic transformation rate at 10 years is <1% but might be higher in JAK2-mutated patients with extreme thrombocytosis and those with abnormal karyotype.

TREATMENT

The main goal of therapy is to prevent thrombosis. In this regard, once-daily low-dose aspirin is advised for all patients and twice daily for low-risk disease. Cytoreductive therapy is advised for high-risk and optional for intermediate-risk disease. First-line cytoreductive drugs of choice are hydroxyurea and pegylated interferon-α and second-line busulfan.

ADDITIONAL CONTENT

The current review includes specific treatment strategies in the context of extreme thrombocytosis, pregnancy, splanchnic vein thrombosis, perioperative care, and post-essential thrombocythemia MF, as well as new investigational drugs.

Digital gangrene: can be the first manifestation of essential thrombocythemia? a case report

Introduction and importance

Essential thrombocythemia (ET) is a rare chronic myeloproliferative hematologic disorder, leading to an elevated platelet count. Two-thirds of patients are asymptomatic during their lifetime, while others may experience symptoms like redness, congestion, and erythromelalgia after long symptom-free intervals.

Case presentation

The authors present a rare instance of a 55-year-old female who, despite receiving aspirin and losartan treatment, eventually developed digital gangrene. In further work-ups, she had an elevated platelet count and a positive JAK 2 mutation. Her platelet count was reduced throughout treatment with aspirin, hydroxyurea, and heparin, which was followed by the necrotic tip of her index finger being surgically debrided.

Clinical discussion

Significant symptoms, such as severe acrocyanosis and even peripheral gangrene, can be treated with a single dose of aspirin. Daily aspirin consumption withstanding, this case developed the severe form of ET. In addition, while thrombocytosis predisposes patients to thrombotic complications in theory, there is little evidence to support a correlation between absolute platelet count and thrombosis.

Conclusion

The initial symptom of ET could be such severe and uncommon that may develop arterial acral thrombosis despite previous daily low-dose aspirin consumption.

Cytoreduction for ET and PV: who, what, when, and how?

Thrombotic complications are the primary contributor to morbidity and mortality in essential thrombocythemia (ET) and polycythemia vera (PV). Cytoreductive therapy is the main tool for primary or tertiary thrombosis prevention in these diseases. In general, high-thrombotic-risk patients and those with symptoms that may be ameliorated from cytoreductive therapy are candidates for this treatment, although the decision is highly individualized. Approved options for cytoreduction in ET and PV include hydroxyurea, long-acting interferons, anagrelide in ET, and ruxolitinib in PV. Selecting the ideal agent requires careful consideration of the toxicity profiles and individual treatment goals. In this review the existing literature on cytoreductive decisions in ET and PV is summarized, with an emphasis on risk-stratification, highlighting the need for personalized care in order to maximize the benefit of these therapies while minimizing toxicities.

Significant heterogeneity in management of calreticulin-mutated essential thrombocythemia and its progression to myelofibrosis: results of a national survey

Despite the recent publication of calreticulin (CALR)-mutated essential thrombocythemia (ET) management guidelines by the European Leukemia Net (ELN), there remains a paucity of data regarding the optimal way to manage this condition. To determine practice around Australia, we constructed a survey asking investigation and treatment questions in a hypothetical case of a young woman with CALR-mutated ET and subsequent progression to myelofibrosis. 51 of 88 hematologists replied. The responses demonstrated significant heterogeneity in specific issues such as the use of aspirin, when to initiate cytoreduction, the preferred type of cytoreduction, and platelet targets. These observations support the ELN acknowledgment that a strong evidence base for many management recommendations is lacking in this disease, and that substantial further research is needed.

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).

Acute myocardial infarction in myeloproliferative neoplasms

Myeloproliferative neoplasms (MPNs) are a heterogeneous group of hematologic malignancies characterized by an abnormal proliferation of cells of the myeloid lineage. Affected individuals are at increased risk for cardiovascular and thrombotic events. Myocardial infarction (MI) may be one of the earliest clinical manifestations of MPNs or may be a thrombotic complication that develops during the natural course of the disease. In the present review, we examine the epidemiology, pathogenesis, clinical presentation, and management of MI in MPNs based on the available literature. Moreover, we review potential biomarkers that could mediate the MI-MPNs crosstalk, from classical biochemical tests, e.g., lactate dehydrogenase, creatine kinase and troponins, to pro-inflammatory cytokines, oxidative stress markers, and clonal hematopoiesis.

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

PURPOSE

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

SUMMARY

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

CONCLUSION

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

Arterial and Venous Thromboembolic Complications in 832 Patients with BCR-ABL-Negative Myeloproliferative Neoplasms

Arterial (ATE) and venous (VTE) thromboembolic complications are common causes of morbidity and mortality in BCR-ABL-negative myeloproliferative neoplasms (MPNs). However, there are few studies that include all MPN subtypes and focus on both MPN-associated ATE and VTE. In our single-center retrospective study of 832 MPN patients, a total of 180 first thromboembolic events occurred during a median follow-up of 6.6 years (range: 0-37.6 years), of which 105 were VTE and 75 were ATE. The probability of a vascular event at the end of the follow-up period was 36.2%, and the incidence rate for all first ATE/VTE was 2.43% patient/year. The most frequent VTE localizations were deep vein thrombosis with or without pulmonary embolism (incidence rate: 0.59% patient/year), while strokes were the most frequent ATE with an incidence rate of 0.32% patient/year. When comparing the group of patients with ATE/VTE (n = 180) and the group without such an event (n = 652) using multivariate Cox regression analyses, patients with polycythemia vera (hazard ratio [HR]: 1.660; [95% confidence interval [CI] 1.206, 2.286]) had a significantly higher risk of a thromboembolic event than the other MPN subtypes. In contrast, patients with a CALR mutation had a significantly lower risk of thromboembolism compared with JAK2-mutated MPN patients (HR: 0.346; [95% CI: 0.172, 0.699]). In summary, a high incidence of MPN-associated VTE and ATE was observed in our retrospective study. While PV patients or generally JAK2-mutated MPN patients had a significantly increased risk of such vascular events, this risk was reduced in CALR-mutated MPN patients.

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

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

Polycythemia vera: 2024 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Polycythemia vera (PV) is a JAK2-mutated myeloproliferative neoplasm characterized by clonal erythrocytosis; other features include leukocytosis, thrombocytosis, splenomegaly, pruritus, constitutional symptoms, microcirculatory disturbances, and increased risk of thrombosis and progression into myelofibrosis (post-PV MF) or acute myeloid leukemia (AML).

DIAGNOSIS

A working diagnosis is considered in the presence of a JAK2 mutation associated with hemoglobin/hematocrit levels of >16.5 g/dL/49% in men or 16 g/dL/48% in women; morphologic confirmation by bone marrow examination is advised but not mandated.

CYTOGENETICS

Abnormal karyotype is seen in 15%-20% of patients with the most frequent sole abnormalities being +9 (5%), loss of chromosome Y (4%), +8 (3%), and 20q- (3%).

MUTATIONS

Over 50% of patients harbor DNA sequence variants/mutations other than JAK2, with the most frequent being TET2 (18%) and ASXL1 (15%). Prognostically adverse mutations include SRSF2, IDH2, RUNX1, and U2AF1, with a combined incidence of 5%-10%.

SURVIVAL AND PROGNOSIS

Median survival is ⁓15 years but exceeds 35 years for patients aged ≤40 years. Risk factors for survival include older age, leukocytosis, abnormal karyotype, and the presence of adverse mutations. Twenty-year risk for thrombosis, post-PV MF, or AML are ⁓26%, 16% and 4%, respectively.

RISK FACTORS FOR THROMBOSIS

Two risk categories are considered: high (age >60 years or thrombosis history) and low (absence of both risk factors). Additional predictors for arterial thrombosis include cardiovascular risk factors and for venous thrombosis higher absolute neutrophil count and JAK2V617F allele burden.

TREATMENT

Current goal of therapy is to prevent thrombosis. Periodic phlebotomy, with a hematocrit target of <45%, combined with once- or twice-daily aspirin (81 mg) therapy, absent contraindications, is the backbone of treatment in all patients, regardless of risk category. Cytoreductive therapy is reserved for high-risk disease with first-line drugs of choice being hydroxyurea and pegylated interferon-α and second-line busulfan and ruxolitinib. In addition, systemic anticoagulation is advised in patients with venous thrombosis history.

ADDITIONAL TREATMENT CONSIDERATIONS

At the present time, we do not consider a drug-induced reduction in JAK2V617F allele burden, which is often incomplete and seen not only with peg-IFN but also with ruxolitinib and busulfan, as an indicator of disease-modifying activity, unless accompanied by cytogenetic and independently-verified morphologic remission. Accordingly, we do not use the specific parameter to influence treatment choices. The current review also includes specific treatment strategies in the context of pregnancy, splanchnic vein thrombosis, pruritus, perioperative care, and post-PV MF.

Toe Gangrene as the First Presenting Symptom of Essential Thrombocythemia: A Case Report

Essential thrombocythemia is a myeloproliferative neoplasm. Thrombosis and bleeding complications are common with myeloproliferative neoplasms, particularly essential thrombocythemia and polycythemia vera. Here, we report the case of a 52-year-old female who presented initially with painful toe swelling and discoloration. Initial imaging showed a small abscess. An incision and drainage, and debridement of toe dry gangrene were performed twice in two months with no improvement in her complaint and worsening discoloration, ending in a toe amputation. Two years later, the patient was referred to a hematology clinic for a high platelet count. On review of her medical records, the patient had the same numbers during the initial presentation. The patient's condition was diagnosed retrogradely by a hematologist as essential thrombocythemia. This case sheds light on myeloproliferative neoplasm as a differential diagnosis in patients with atypical thrombosis. Thinking in such a way could have diagnosed our patient two years earlier.

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

OPINION STATEMENT

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

Bomedemstat as an investigative treatment for myeloproliferative neoplasms

INTRODUCTION

Myeloproliferative neoplasm (MPN) is a heterogeneous group of hematopoietic stem cell disorders characterized by clonal proliferation of one of more of the hematopoietic stem cell lineages. Clinical manifestations result from uncontrolled myeloproliferation, extramedullary hematopoiesis with splenomegaly and excessive inflammatory cytokine production. Currently available therapy improves hematologic parameters and symptoms but does not adequately address the underlying neoplastic biology. Bomedemstat has thus far demonstrated clinical efficacy and tolerability in the treatment of MPNs with recent evidence of impacting the malignant stem cell population.

AREAS COVERED

This review summarizes the mechanisms of action, pharmacokinetics and pharmacodynamics, safety and efficacy of bomedemstat in MPN with specific emphasis on essential thrombocythemia (ET) and myelofibrosis (MF).

EXPERT OPINION

In patients with MPNs, bomedemstat appears effective and well tolerated. The signs and symptoms of these diseases are managed as a reduction in the frequency of mutant cells was demonstrated in patients with ET and MF. Ongoing and planned studies of bomedemstat in MPN will establish the position of bomedemstat in MPNs and may help to redefine treatment endpoints of MPNs in the future.

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.

Pathological and genomic features of myeloproliferative neoplasms associated with splanchnic vein thrombosis in a single-center cohort

Here, we reviewed clinical-morphological data and investigated mutational profiles by NGS in a single-center series of 58 consecutive MPN-SVT patients admitted to our hospital between January 1979 and November 2021. We identified 15.5% of PV, 13.8% of ET, 34.5% of PMF, 8.6% of SMF and 27.6% of MPN-U. Most cases (84.5%) carried JAK2V617F mutation, while seven patients were characterized by other molecular markers, namely MPL in four and CALR mutations in three cases. NGS was performed in 54 (93.1%) cases: the most frequent additional mutations were found in TET2 (27.8%) and DNMT3A (16.7%) genes, whereas 25 (46.3%) patients had no additional mutation. Cases with JAK2V617F homozygosity had a higher median number of additional mutations than those with low allele burden. More importantly, all cases of leukemic evolution were characterized by a higher median number of co-mutations, and a co-mutational pattern of high-risk lesions, such as truncating mutations of ASXL1, bi-allelic TP53 loss, and CSMD1 mutations. Nevertheless, no difference was found between cases with and without additional somatic mutations regarding fibrotic progression, SVT recurrence, other thrombo-hemorrhagic complications, or death. After a median follow-up of 7.1 years, ten deaths were recorded; fibrotic progression/leukemic evolution was ascertained in one (1.7%) and six (10.3%) patients, respectively, while 22 (37.9%) patients suffered from recurrent thrombosis. In conclusion, our data underline the importance of using NGS analysis in the management of MPN-related SVT as it can support the MPN diagnosis, particularly in "triple-negative" cases, and provide additional information with potential consequences on prognosis and therapeutic strategies.

Anagrelide: A Clinically Effective cAMP Phosphodiesterase 3A Inhibitor with Molecular Glue Properties

The mode of action by which the orphan drug anagrelide (1), a potent cAMP phosphodiesterase 3A inhibitor, reduces blood platelet count in humans is not well understood. Recent studies indicate that 1 stabilizes a complex between PDE3A and Schlafen 12, protecting it from degradation while activating its RNase activity.

Continuous Indexing of Fibrosis (CIF): improving the assessment and classification of MPN patients

The grading of fibrosis in myeloproliferative neoplasms (MPN) is an important component of disease classification, prognostication and monitoring. However, current fibrosis grading systems are only semi-quantitative and fail to fully capture sample heterogeneity. To improve the quantitation of reticulin fibrosis, we developed a machine learning approach using bone marrow trephine (BMT) samples (n = 107) from patients diagnosed with MPN or a reactive marrow. The resulting Continuous Indexing of Fibrosis (CIF) enhances the detection and monitoring of fibrosis within BMTs, and aids MPN subtyping. When combined with megakaryocyte feature analysis, CIF discriminates between the frequently challenging differential diagnosis of essential thrombocythemia (ET) and pre-fibrotic myelofibrosis with high predictive accuracy [area under the curve = 0.94]. CIF also shows promise in the identification of MPN patients at risk of disease progression; analysis of samples from 35 patients diagnosed with ET and enrolled in the Primary Thrombocythemia-1 trial identified features predictive of post-ET myelofibrosis (area under the curve = 0.77). In addition to these clinical applications, automated analysis of fibrosis has clear potential to further refine disease classification boundaries and inform future studies of the micro-environmental factors driving disease initiation and progression in MPN and other stem cell disorders.

Molecular Genetics of Thrombotic Myeloproliferative Neoplasms: Implications in Precision Oncology

Classical BCR-ABL-negative myeloproliferative neoplasms (MPN) include polycythaemia vera, essential thrombocythaemia, and primary myelofibrosis. Unlike monogenic disorders, a more complicated series of genetic mutations are believed to be responsible for MPN with various degrees of thromboembolic and bleeding complications. Thrombosis is one of the early manifestations in patients with MPN. To date, the driver genes responsible for MPN include JAK2, CALR, MPL, TET2, ASXL1, and MTHFR. Affords have been done to elucidate these mutations and the incidence of thromboembolic events. Several lines of evidence indicate that mutations in JAK2, MPL, TET2 and ASXL1 gene and polymorphisms in several clotting factors (GPIa, GPIIa, and GPIIIa) are associated with the occurrence and prevalence of thrombosis in MPN patients. Some polymorphisms within XRCC1, FBG, F2, F5, F7, F12, MMP9, HPA5, MTHFR, SDF-1, FAS, FASL, TERT, ACE, and TLR4 genes may also play a role in MPN manifestation. This review aims to provide an insightful overview on the genetic perspective of thrombotic complications in patients with MPN.

Prevalence and clinical outcomes of polycythemia vera and essential thrombocythemia with hydroxyurea resistance or intolerance

INTRODUCTION

To determine the prevalence, clinical outcomes, and factors associated with hydroxyurea (HU) resistance or intolerance among polycythemia vera (PV) and essential thrombocythemia (ET) patients.

METHODS

This study was a retrospective cohort study including PV and ET patients diagnosed by WHO criteria and treated with HU between January 2000 and June 2020. Clinical features, laboratory data, and resistance or intolerance of HU were collected. The prevalence, clinical outcomes, and associated factors of HU resistance or intolerance were analyzed.

RESULTS

There were 260 patients including 144 ET and 116 PV. The prevalence of HU resistance or intolerance was 11.9% (31 patients) which was more frequent in ET patients (14.6% vs. 8.6% in PV). Patients who had HU resistance or intolerance significantly increased the risk of bleeding events (HR 2.64; 95% CI 1.19-5.85, P = 0.017). The risk factors of HU resistance or intolerance were low baseline hemoglobin levels (HR 0.90; 95%CI 0.84-0.97, P = 0.01), age more than 60 years old (HR 3.98; 95% CI 2.08-7.62, P < 0.001) and splenomegaly (HR 2.08; 95% CI 1.03-4.21, P = 0.04).

CONCLUSIONS

The prevalence of HU resistance or intolerance in PV and ET patients was 11.9%. Patients with HU resistance or intolerance significantly increased the risk of bleeding complications.

A multicenter, open-label study for efficacy and safety evaluation of anagrelide in patients with treatment-naïve, high-risk essential thrombocythemia as a primary treatment

As the discussion of first-line anagrelide treatment is ongoing, we aimed to prospectively examine the efficacy and safety of anagrelide in cytoreduction therapy-naïve high risk essential thrombocythemia (ET) patients in Korea. Seventy patients from 12 centers were treated with anagrelide monotherapy for up to 8 weeks, followed up until 24 months. At week 8, 50.0% of the patients were able to achieve platelet < 600 x 109/L, and by 12 months, 55/70 (78.6%) patients stayed on anagrelide, and 40.0% patients showed platelet normalization. 14 patients required additional hydroxyurea (HU) for cytoreduction. The median daily dose of needed HU was 500mg (range 250mg - 1500mg). The efficacy was independent of the somatic mutation status. There were 4 thromboembolic events and 7 bleeding events during the follow-up period. The most common adverse events associated with anagrelide use were headache, followed by palpitation/chest discomfort, edema and generalized weakness/fatigue. 7 patients wished to discontinue anagrelide treatment due to adverse events (3 due to headache; 2 due to edema; 1 due to palpitation and 1 due to skin eruption). All in all, first-line anagrelide treatment showed a favorable response with tolerable safety profiles regardless of somatic mutation status.

Anagrelide-associated Cardiomyopathy and Heart Failure in a Patient with Essential Thrombocythemia: A Case Report and Literature Review

Anagrelide is used worldwide to treat essential thrombocythemia (ET) by reducing platelet counts. Cardiomyopathy and heart failure (HF) are rare but serious complications associated with anagrelide use, although no cases were reported during Japanese Phase I to III studies. A 46-year-old, otherwise healthy, Japanese ET patient developed HF with reduced ejection fraction after 18 months of treatment with 1.0-3.5 mg of anagrelide daily. HF was stabilized with anagrelide withdrawal and guideline-directed HF therapy. The cardiac function returned to normal after six months. This case suggests that anagrelide can cause cardiomyopathy and HF in ET patients, regardless of nationality, comorbid cardiovascular conditions, or therapy duration.

Practical management of the haemorrhagic complications of myeloproliferative neoplasms

Myeloproliferative neoplasms can be associated with bleeding manifestations which can cause significant morbidities. Although haematologists are aware of the likelihood of this complication in the setting of myeloproliferative neoplasms, it may often be overlooked especially in patients with no extreme elevation of blood counts and those with myelofibrosis. Acquired von Willebrand syndrome and platelet dysfunction are the two common diagnoses to be considered in this regard. In this review article, we discuss the mechanisms for the development of these rare bleeding disorders, their diagnosis and practical management.

Safety and efficacy of anagrelide in Japanese post-marketing surveillance, with subgroup analyses on the effect of previous cytoreductive therapies, age, and starting dose

BACKGROUND

In Japan, anagrelide has been approved for use in patients with essential thrombocythemia. Here, the safety and efficacy of anagrelide was assessed in clinical practice as post-marketing surveillance. Subgroup analyses were conducted to compare patients (1) with or without a history of cytoreductive therapy (CRT), (2) <60 or ≥60 years of age, and (3) with an anagrelide starting dose of ≤0.5 mg/day or 1.0 mg/day.

METHODS

Data were collected for all patients who received anagrelide, with an observation period of 12 months after treatment initiation.

RESULTS

Of the 648 patients, 54.3% experienced adverse drug reactions (ADRs). The most commonly reported ADRs were headaches, palpitations, and anemia. No significant difference was observed in overall ADRs across patient subgroups. A significantly higher incidence of headaches was observed in patients < 60 years versus those ≥ 60 years (P < 0.001). The incidence of anemia and serious ADRs were significantly higher in patients ≥ 60 years, and those with a history of CRT (P < 0.05). The discontinuation rate at 6 months was significantly lower in patients started at the lower anagrelide dose (P < 0.05). Platelet counts decreased in all analyzed groups.

CONCLUSIONS

This surveillance showed that anagrelide has a tolerable safety and efficacy profile.

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.

SURPASS-ET: phase III study of ropeginterferon alfa-2b versus anagrelide as second-line therapy in essential thrombocythemia

Patients diagnosed with high-risk essential thrombocythemia (ET) have limited treatment options to reduce the risk of thrombosis and lessen the progression of the disease by targeting the molecular source. Hydroxyurea is the recommended treatment, but many patients experience resistance or intolerance. Anagrelide is an approved second-line option for ET, but concerns of a higher frequency of disease transformation may affect its role as a suitable long-term option. Interferons have been evaluated in myeloproliferative neoplasms for over 30 years, but early formulations had safety and tolerability issues. SURPASS-ET (NCT04285086) is a phase III, open-label, multicenter, global, randomized, active-controlled trial that will evaluate the safety, efficacy, tolerability and pharmacokinetics of ropeginterferon alfa-2b compared with anagrelide as second-line therapy in high-risk ET.

Advances in Risk Stratification and Treatment of Polycythemia Vera and Essential Thrombocythemia

PURPOSE OF REVIEW

Estimating and modifying thrombotic risk is currently the mainstay of care for patients with polycythemia vera (PV) and essential thrombocythemia (ET). In recent years, however, increased attention has shifted towards quality of life and disease modification. In this review, we discuss recent advances in risk stratification, present updated results for ruxolitinib and interferon randomized clinical trials, discuss new approaches in antiplatelet and anticoagulant treatment, and summarize early phase trials of novel agents and emerging therapeutic concepts for the treatment of PV and ET.

RECENT FINDINGS

International collaborations and novel technologies, i.e., next-generation sequencing and machine learning techniques, have demonstrated excellent abilities to improve thrombotic risk stratification in PV and ET. Updated results from ruxolitinib and interferon randomized clinical trials have confirmed excellent efficacy and safety of these agents, both as first- and second-line treatments. Early trials of novel agents (histone deacetylase inhibitors, telomerase inhibitors, lysine-specific demethylase-1 inhibitors, human double-minute 2 inhibitors, and hepcidin mimetics) have shown encouraging efficacy and safety in blood count control, reduction of splenomegaly, and alleviation of disease-related symptoms. Finally, accumulating evidence suggested that direct oral anticoagulants may be a valid therapeutic alternative to warfarin for prolonged thromboprophylaxis. International collaborations ("big data") with the help of new technologies represent an exciting new approach to analyze rare outcomes in rare diseases, especially for identifying novel prognostic biomarkers in PV and ET. Randomized clinical trials are also needed to fully elucidate whether novel agents may establish new standards of care.

Anagrelide for platelet-directed cytoreduction in polycythemia vera: Insights into utility and safety outcomes from a large multi-center database

Anagrelide (ANA) is a platelet-specific cytoreductive agent utilized in the guideline-directed management of high-risk essential thrombocythemia. In the context of polycythemia vera (PV), ANA is occasionally employed in clinical practice, although data has not consistently demonstrated a benefit to targeting a platelet goal as a therapeutic endpoint. The aim of the current study was to delineate the patterns of ANA use in PV, and to describe outcomes and toxicities. Within a multi-center cohort of 527 patients with PV, 48 received ANA (9 excluded for absent data). 27 (69.2%) had high-risk PV, 10 (25.6%) had prior thrombosis, and none had extreme thrombocytosis, acquired von Willebrand disease, and/or documented resistance to hydroxyurea. While ANA effectively lowered median platelet count, 43.5% of patients had an unresolved thrombocytosis at time of ANA discontinuation. Treatment-emergent adverse events-including headaches, cardiac palpitations and arrhythmias, nausea, vomiting and/or diarrhea-led to ANA discontinuation in 76.9% of patients. Further, three patients experienced arterial thromboses during a median duration of 27.5 months of ANA therapy. In conclusion, this study highlights ANA's restrictive tolerability profile which, compounded by the absence of clear advantage to strict platelet control in PV, suggests the use of ANA should be limited in this setting.

Inhibitors of the Cancer Target Ribonucleotide Reductase, Past and Present

Ribonucleotide reductase (RR) is an essential multi-subunit enzyme found in all living organisms; it catalyzes the rate-limiting step in dNTP synthesis, namely, the conversion of ribonucleoside diphosphates to deoxyribonucleoside diphosphates. As expression levels of human RR (hRR) are high during cell replication, hRR has long been considered an attractive drug target for a range of proliferative diseases, including cancer. While there are many excellent reviews regarding the structure, function, and clinical importance of hRR, recent years have seen an increase in novel approaches to inhibiting hRR that merit an updated discussion of the existing inhibitors and strategies to target this enzyme. In this review, we discuss the mechanisms and clinical applications of classic nucleoside analog inhibitors of hRRM1 (large catalytic subunit), including gemcitabine and clofarabine, as well as inhibitors of the hRRM2 (free radical housing small subunit), including triapine and hydroxyurea. Additionally, we discuss novel approaches to targeting RR and the discovery of new classes of hRR inhibitors.

Cytoreductive treatment and association with platelet function and maturity in patients with essential thrombocythaemia

Patients with essential thrombocythaemia (ET) have an increased risk of thromboembolic events, which may differ according to different cytoreductive drugs. We investigated the effect of cytoreductive treatment on platelet function and turnover in ET patients. Blood samples were obtained at 1 and 24 h after aspirin intake. Platelet function was evaluated by platelet aggregation and flow cytometry. Platelet turnover was assessed by immature platelet count, immature platelet fraction (IPF) and mean platelet volume (MPV). A total of 47 ET patients were included and grouped into 21 patients not receiving cytoreductive treatment, 15 patients receiving hydroxycarbamide and 11 patients receiving pegylated interferon alpha (peg‐IFN). Patients receiving peg‐IFN had significantly higher IPF and MPV than the other ET groups. Patients not receiving cytoreductive treatment had significantly higher platelet aggregation 24 h after aspirin intake than the other ET groups (p‐values from 0.03 to 0.0002). Patients receiving hydroxycarbamide had significantly higher expression of platelet granule makers, P‐selectin and CD63, than patients receiving peg‐IFN (p‐values ≤0.003). Cytoreduction provides more consistent platelet inhibition compared with no cytoreductive treatment. Moreover, peg‐IFN provides superior inhibition of platelet activation markers than hydroxycarbamide, which in part may explain differences in risk of thromboembolic events in ET patients.

Treatment options and pregnancy management for patients with PV and ET

Polycythemia vera (PV) and essential thrombocythemia (ET) are the two most common subtypes of Philadelphia chromosome-negative myeloproliferative neoplasm (MPN). PV results in erythrocytosis and ET in thrombocytosis. The discovery of JAK2 mutations in the majority of patients with MPN over the last 2 decades has led to the development of JAK inhibitors. Because PV and ET progress relatively slowly, the main treatment strategy for these two diseases is to prevent thrombotic complications. The first-line agent for both PV and ET is hydroxyurea, although some patients are intolerant or refractory to this compound and need other treatment options. Notably, hydroxyurea is contraindicated during pregnancy. In addition to JAK inhibitors, several new agents, such as HDAC inhibitors, LSD1 inhibitors, MDM2 inhibitors and hepcidin mimetics, have been developed as treatment options. Classical agents, such as busulfan and interferon, are still used to treat patients with PV or ET as well. Based on this context, treatment options and pregnancy management for patients with PV or ET are discussed in this review.

Thromboinflammation in Myeloproliferative Neoplasms (MPN)-A Puzzle Still to Be Solved

Myeloproliferative neoplasms (MPNs), a group of malignant hematological disorders, occur as a consequence of somatic mutations in the hematopoietic stem cell compartment and show excessive accumulation of mature myeloid cells in the blood. A major cause of morbidity and mortality in these patients is the marked prothrombotic state leading to venous and arterial thrombosis, including myocardial infarction (MI), deep vein thrombosis (DVT), and strokes. Additionally, many MPN patients suffer from inflammation-mediated constitutional symptoms, such as fever, night sweats, fatigue, and cachexia. The chronic inflammatory syndrome in MPNs is associated with the up-regulation of various inflammatory cytokines in patients and is involved in the formation of the so-called MPN thromboinflammation. JAK2-V617F, the most prevalent mutation in MPNs, has been shown to activate a number of integrins on mature myeloid cells, including granulocytes and erythrocytes, which increase adhesion and drive venous thrombosis in murine knock-in/out models. This review aims to shed light on the current understanding of thromboinflammation, involvement of neutrophils in the prothrombotic state, plausible molecular mechanisms triggering the process of thrombosis, and potential novel therapeutic targets for developing effective strategies to reduce the MPN disease burden.

Thromboinflammation in Myeloproliferative Neoplasms (MPN)-A Puzzle Still to Be Solved

Myeloproliferative neoplasms (MPNs), a group of malignant hematological disorders, occur as a consequence of somatic mutations in the hematopoietic stem cell compartment and show excessive accumulation of mature myeloid cells in the blood. A major cause of morbidity and mortality in these patients is the marked prothrombotic state leading to venous and arterial thrombosis, including myocardial infarction (MI), deep vein thrombosis (DVT), and strokes. Additionally, many MPN patients suffer from inflammation-mediated constitutional symptoms, such as fever, night sweats, fatigue, and cachexia. The chronic inflammatory syndrome in MPNs is associated with the up-regulation of various inflammatory cytokines in patients and is involved in the formation of the so-called MPN thromboinflammation. JAK2-V617F, the most prevalent mutation in MPNs, has been shown to activate a number of integrins on mature myeloid cells, including granulocytes and erythrocytes, which increase adhesion and drive venous thrombosis in murine knock-in/out models. This review aims to shed light on the current understanding of thromboinflammation, involvement of neutrophils in the prothrombotic state, plausible molecular mechanisms triggering the process of thrombosis, and potential novel therapeutic targets for developing effective strategies to reduce the MPN disease burden.

Treatment and Clinical Endpoints in Polycythemia Vera: Seeking the Best Obtainable Version of the Truth

Polycythemia vera (PV) is a Philadelphia chromosome-negative myeloproliferative neoplasm driven by the JAK2 V617F (or rarely exon 12) mutation. Its natural history can extend over a few decades, and therefore treatment planning is predicated on continual re-assessment of traditional risk features (age, prior thrombosis) to evaluate the need for cytoreduction besides foundational therapy with low-dose aspirin and stringent phlebotomy. Shorter- and longer-term patient goals should be considered in light of several variables such as co-morbid conditions (especially cardiovascular risk factors), disease symptoms, and the risk-benefit profile of available drugs. While hydroxyurea has been the pro forma choice of cytoreduction for many practitioners over the last half-century, the more recent regulatory approvals of ruxolitinib and ropeginterferon-alfa-2b, based on phase 3 randomized trials, highlight an expanding portfolio of active drugs. Obtaining high-level evidence for short-term clinical trial endpoints such as hematocrit control, symptom burden/quality of life, splenomegaly, and JAK2 V617F allele burden lies within the timeline of most studies. However, in many cases, it may not be possible to adequately power trials to capture significant differences in the typically low event rates of thrombosis, as well as longer-horizon endpoints such as evolution to myelofibrosis and acute myeloid leukemia, and survival. This Perspective highlights the challenges of addressing these data gaps and outstanding questions in the emerging treatment landscape of PV.

Thrombosis and hemorrhage in myeloproliferative neoplasms: The platelet perspective

Classical myeloproliferative neoplasm (MPN), also known as BCR-ABL-negative MPN, is a clonal disease characterized by abnormal expansion of hematopoietic stem cells. It has been demonstrated that MPN patients are more susceptible to thrombotic events compared to the general population. Therefore, researchers have been exploring the treatment for MPN thrombosis. However, antithrombotic therapies have brought another concern for the clinical management of MPN because they may cause bleeding events. When thrombosis and bleeding, two seemingly contradictory complications, occur in MPN patients at the same time, they will lead to more serious consequences. Therefore, it is a major challenge to achieving the best antithrombotic effect and minimizing bleeding events simultaneously. To date, there has yet been a perfect strategy to meet this challenge and therefore a new treatment method needs to be established. In this article, we describe the mechanism of thrombosis and bleeding events in MPN from the perspective of platelets for the first time. Based on the double-sided role of platelets in MPN, optimal antithrombotic treatment strategies that can simultaneously control thrombosis and bleeding at the same time may be formulated by adjusting the administration time and dosage of antiplatelet drugs. We argue that more attention should be paid to the critical role of platelets in MPN thrombosis and MPN bleeding in the future, so as to better manage adverse vascular events in MPN.