Treatment of essential thrombocythemia in Europe: a prospective long-term observational study of 3649 high-risk patients in the Evaluation of Anagrelide Efficacy and Long-term Safety study

ROP-ET: a prospective phase III trial investigating the efficacy and safety of ropeginterferon alfa-2b in essential thrombocythemia patients with limited treatment options

Interferon-based therapies, such as ropeginterferon alfa-2b have emerged as promising disease-modifying agents for myeloproliferative neoplasms (MPNs), including essential thrombocythemia (ET). Current ET treatments aim to normalize hematological parameters and reduce the thrombotic risk, but they do not modify the natural history of the disease and hence, have no impact on disease progression. Ropeginterferon alfa-2b (trade name BESREMi®), a novel, monopegylated interferon alfa-2b with an extended administration interval, has demonstrated a robust and sustained efficacy in polycythemia vera (PV) patients. Given the similarities in disease pathophysiology and treatment goals, ropeginterferon alfa-2b holds promise as a treatment option for ET. The ROP-ET trial is a prospective, multicenter, single-arm phase III study that includes patients with ET who are intolerant or resistant to, and/or are ineligible for current therapies, such as hydroxyurea (HU), anagrelide (ANA), busulfan (BUS) and pipobroman, leaving these patients with limited treatment options. The primary endpoint is a composite response of hematologic parameters and disease-related symptoms, according to modified European LeukemiaNet (ELN) criteria. Secondary endpoints include improvements in symptoms and quality of life, molecular response and the safety profile of ropeginterferon alfa-2b. Over a 3-year period the trial assesses longer term outcomes, particularly the effects on allele burden and clinical outcomes, such as disease-related symptoms, vascular events and disease progression. No prospective clinical trial data exist for ropeginterferon alfa-2b in the planned ET study population and this study will provide new findings that may contribute to advancing the treatment landscape for ET patients with limited alternatives. TRIAL REGISTRATION: EU Clinical Trials Register; EudraCT, 2023-505160-12-00; Registered on October 30, 2023.

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.

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).

Prediction of major bleeding events in 1381 patients with essential thrombocythemia

The goal of therapy in essential thrombocythemia (ET) is reducing thrombotic risk. No algorithm to predict hemorrhage risk exists. The impact ofanti-platelet, cytoreductive and anticoagulation therapies on risk of major bleeding (MB) was evaluated. MB events were retrospectively analyzed in 1381 ET from 10 European centers. There were 0.286 MB events/person-year. Neither the International Thrombosis Prognostic Score for thrombosis in essential thrombocythemia (IPSET-t) nor the revised IPSET-t (r-IPSET-t) was predictive for hemorrhage-free survival at 10 years (p = 0.092 vs p = 0.1). Ageand leukocyte count were MB risk factors, while low hemoglobin was protective. For ET with extreme thrombocytosis (ExtT) and leukocytosis cytoreduction was not protective. MB were more frequent in ET with ExtT who received anticoagulation. Antiplatelet therapy was not, while anticoagulation was a risk factor for MB (HR 3.05, p = 0.016, CI 1.23-7.56), in particular vitamin K antagonists (22.6% of those treated had a MB event, HR 2.96, p = 0.004, CI 1.41-6.22). Survival at 10 years was associated with hemorrhage (OR 2.54, p < 0.001) but not thrombosis (HR 0.95, p = 0.829). Hemorrhage has a higher risk of mortality than thrombosis. Improved risk stratification for MB is necessary. The choice of anticoagulation, cytoreduction and antiplatelet therapies is an important area of research in ET.

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.

Primary Arterial Hypertension and Drug-Induced Hypertension in Philadelphia-Negative Classical Myeloproliferative Neoplasms: A Systematic Review

The impact of primary arterial hypertension (HTN) in myeloproliferative neoplasms (MPNs) remains unclear, with scant literature available, mostly focusing on cardiovascular risk factors as a singular entity or on organ-specific HTN. Furthermore, available studies reporting findings on drug-induced HTN in MPNs report varying and contradictory findings. In consideration of the above, this study set out to systematically review the available literature and shed light on the occurrence of HTN in MPNs, its association with thrombosis, as well as the drugs used in MPN management that could increase blood pressure. The literature search yielded 598 potentially relevant records of which 315 remained after the duplicates (n = 283) were removed. After we screened the titles and the abstracts of these publications, we removed irrelevant papers (n = 228) and evaluated the full texts of 87 papers. Furthermore, 13 records did not meet the inclusion criteria and were excluded from the systematic review. Finally, a total of 74 manuscripts were entered into the qualitative synthesis and included in the present systematic review. Our systematic review highlights that HTN is the most common comorbidity encountered in MPNs, with an impact on both the occurrence of thrombosis and survival. Moreover, drug-induced HTN remains a challenge in the management of MPNs. Further research should investigate the characteristics of patients with MPNs and HTN, as well as clarify the contribution of HTN to the development of thrombotic complications, survival and management in MPNs. In addition, the relationship between clonal hematopoiesis of indeterminate potential, HTN, cardiovascular disease and MPNs requires examination in upcoming assessments.

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

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

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.

Recombinant Interferon-β in the Treatment of Polycythemia Vera and Related Neoplasms: Rationales and Perspectives

About 30 years ago, the first clinical trials of the safety and efficacy of recombinant interferon-α2 (rIFN-α2) were performed. Since then, several single-arm studies have shown rIFN-α2 to be a highly potent anticancer agent against several cancer types. Unfortunately, however, a high toxicity profile in early studies with rIFN-α2 -among other reasons likely due to the high dosages being used-disqualified rIFN-α2, which was accordingly replaced with competitive drugs that might at first glance look more attractive to clinicians. Later, pegylated IFN-α2a (Pegasys) and pegylated IFN-α2b (PegIntron) were introduced, which have since been reported to be better tolerated due to reduced toxicity. Today, treatment with rIFN-α2 is virtually outdated in non-hematological cancers, where other immunotherapies-e.g., immune-checkpoint inhibitors-are routinely used in several cancer types and are being intensively investigated in others, either as monotherapy or in combination with immunomodulatory agents, although only rarely in combination with rIFN-α2. Within the hematological malignancies, rIFN-α2 has been used off-label for decades in patients with Philadelphia-negative chronic myeloproliferative neoplasms (MPNs)-i.e., essential thrombocythemia, polycythemia vera, and myelofibrosis-and in recent years rIFN-α2 has been revived with the marketing of ropeginterferon-α2b (Besremi) for the treatment of polycythemia vera patients. Additionally, rIFN-α2 has been revived for the treatment of chronic myelogenous leukemia in combination with tyrosine kinase inhibitors. Another rIFN formulation-recombinant interferon-β (rIFN-β)-has been used for decades in the treatment of multiple sclerosis but has never been studied as a potential agent to be used in patients with MPNs, although several studies and reviews have repeatedly described rIFN-β as an effective anticancer agent as well. In this paper, we describe the rationales and perspectives for launching studies on the safety and efficacy of rIFN-β in patients with MPNs.

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.

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 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.

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.

CRLF3 plays a key role in the final stage of platelet genesis and is a potential therapeutic target for thrombocythemia

The process of platelet production has so far been understood to be a 2-stage process: megakaryocyte maturation from hematopoietic stem cells followed by proplatelet formation, with each phase regulating the peripheral blood platelet count. Proplatelet formation releases into the bloodstream beads-on-a-string preplatelets, which undergo fission into mature platelets. For the first time, we show that preplatelet maturation is a third, tightly regulated, critical process akin to cytokinesis that regulates platelet count. We show that deficiency in cytokine receptor-like factor 3 (CRLF3) in mice leads to an isolated and sustained 25% to 48% reduction in the platelet count without any effect on other blood cell lineages. We show that Crlf3-/- preplatelets have increased microtubule stability, possibly because of increased microtubule glutamylation via the interaction of CRLF3 with key members of the Hippo pathway. Using a mouse model of JAK2 V617F essential thrombocythemia, we show that a lack of CRLF3 leads to long-term lineage-specific normalization of the platelet count. We thereby postulate that targeting CRLF3 has therapeutic potential for treatment of thrombocythemia.

Synthesis of pyrimidine-containing alkaloids

This review deals with the synthesis of naturally occurring alkaloids containing partially or completely saturated pyrimidine nuclei. The interest in these compounds is associated with their structural diversity, high biological activity and toxicity. The review is divided into four parts, each of which describes a number of synthetic methodologies toward structurally different naturally occurring alkaloids containing saturated cyclic six-membered amidine, guanidine, aminal and urea (thiourea) moieties, respectively. The development of various synthetic strategies for the preparation of these compounds has remarkably increased during the past few decades. This is primarily due to the fact that some of these compounds are isolated only in limited quantities, which makes it practically impossible to study their full structural characteristics and biological activity.

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.

Thrombosis in myeloproliferative neoplasms during cytoreductive and antithrombotic drug treatment

A state-of-the-art lecture titled "Myeloproliferative Neoplasm-associated Thrombosis" was presented at the ISTH congress in 2021. We summarize here the main points of the lecture with two purposes: to report the incidence rates of major thrombosis in polycythemia vera and essential thrombocythemia and to discuss to what extent cytoreductive therapy and antithrombotic drugs have reduced the incidence of these events. Unfortunately, the incidence rate of thrombosis remains high, ranging between 2 and 5/100 person-years. It is likely that new drugs such as interferon and ruxolitinib can be more efficacious given their cytoreductive and anti-inflammatory activities. Despite prophylaxis with vitamin K antagonists and direct oral anticoagulants after venous thrombosis in either common sites or splanchnic or cerebral sites, the incidence rate is still elevated, as high as 4 to 5/100 person-years. Future studies with new drugs or new strategies should consider thrombosis as the primary endpoint or surrogate biomarkers only if previously validated.

Clinical characteristics, prognostic factors, and outcomes of patients with essential thrombocythemia in Japan: the JSH-MPN-R18 study

We conducted a large-scale, nationwide retrospective study of Japanese patients who were diagnosed with essential thrombocythemia based on the diagnostic criteria in the World Health Organization classification. We investigated clinical characteristics, survival rates, and the incidence of thrombohemorrhagic events as well as risk factors for these events. A total of 1152 patients were analyzed in the present study. Median age at diagnosis was 65 years, the median platelet count was 832 × 10⁹/L, and the positive mutation rates of JAK2V617F, CALR, and MPL were 62.8, 25.1, and 4.1%, respectively. Compared with European and American patients, Japanese patients were more likely to have cardiovascular risk factors and less likely to have systemic symptoms including palpable splenomegaly. Thrombocytosis was identified as a risk factor for hemorrhagic events and prognosis, but not for thrombotic events. The prognostic factors and risk classifications reported in Europe and the United States were generally applicable to Japanese patients. Regarding transformations, secondary myelofibrosis progressed in a time-dependent manner, but progression to acute leukemia was low in "true" ET patients. Skin cancers were less common and gastrointestinal cancers more common as secondary malignancies in Japanese patients, suggesting ethnic differences.

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.

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

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

Pulmonary Arterial Hypertension Secondary to Drugs and Toxins

Pulmonary arterial hypertension secondary to drugs and toxins is an important subgroup of group 1 pulmonary hypertension associated with significant morbidity and mortality. Many drugs and toxins have emerged as risk factors for pulmonary arterial hypertension, which include anorexigens, illicit agents, and several US Food and Drug Administration-approved therapeutic medications. Drugs and toxins are classified as possible or definite risk factors for pulmonary arterial hypertension. This article reviews agents that have been implicated in the development of pulmonary arterial hypertension, their pathologic mechanisms, and methods to prevent the next deadly outbreak of drug- and toxin-induced pulmonary arterial hypertension.

A review of hydroxyurea-related cutaneous adverse events

Introduction: Hydroxyurea (HU) is an S-phase specific oral chemotherapeutic agent that inhibits ribonucleotide diphosphate reductase. It is the most common used cytoreductive drug in patients (pts) with BCR-ABL1 negative myeloproliferative neoplasms (MPN) and sickle cell disease (SCD). The World Health Organization lists HU as an "essential drug". Although most patients tolerate HU well, cutaneous adverse events (CAE) are frequent side effects and may limit its long-term use. This has become increasingly evident in recent years, especially in MPN patients, where CAE were previously underestimated and underdiagnosed.Areas covered: In this review, we present the available literature on HU-related CAE in MPN patients. In particular, data from a recently published and so far, only prospective non-interventional study investigating CAE in 172 MPN patients will be discussed in detail and compared with previously available data. Finally, we give an overview of the management of HU-related CAE in MPN patients and provide recommendations on the practical clinical approach.Expert opinion: In clinical practice, HU associated CAE are common and have important diagnostic and therapeutic consequences. Therefore, they should be considered in all MPN patients treated with HU in the future.

Essential Thrombocythemia in a 15-Year-Old Female: Presentation, Workup, and Treatment Considerations in the Pediatric Population

Essential thrombocythemia (ET) is a diagnosis most often seen in adults but can also present in children in rare cases. This article reviews the presentation, diagnosis, and treatment of ET in a 15-year-old female followed by a review of the literature regarding special considerations in the workup, diagnosis, treatment, and follow-up of ET in the pediatric population.

Thrombocytosis in children and adolescents-classification, diagnostic approach, and clinical management

Secondary thrombocytosis is a frequent secondary finding in childhood infection and inflammation. Primary hereditary thrombocytosis may be caused by germline mutations within the genes encoding key regulators of thrombopoiesis, i.e., thrombopoietin (THPO) and its receptor c-MPL (MPL) or the receptor's effector kinase Januskinase2 (JAK2). Furthermore, somatic mutations in JAK2, MPL, and in the gene-encoding calreticulin (CALR) have been described to act as driver mutations within the so-called Philadelphia-negative myeloproliferative neoplasms (MPNs), namely essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF). Increasing knowledge on the molecular mechanisms and on the clinical complications of these diseases is reflected by the WHO diagnostic criteria and European LeukemiaNet (ELN) recommendations on the management of adult MPN. However, data on childhood thrombocytosis are rare, and no consensus guidelines for pediatric thrombocytosis exist. Current literature has highlighted differences in the epidemiology and molecular pathogenesis of childhood thrombocytosis as compared to adults. Furthermore, age-dependent complications and pharmacological specificities suggest that recommendations tailored to the pediatric population are necessary in clinical practice. Here we summarize literature on classification, diagnostics, and clinical management of childhood thrombocytosis.

Disease and Clinical Characteristics of Patients With a Clinical Diagnosis of Essential Thrombocythemia Enrolled in the MOST Study

Few data exist regarding the disease and clinical characteristics of patients with essential thrombocythemia (ET) in the United States. The ongoing, multicenter, noninterventional, prospective, Myelofibrosis and Essential Thrombocythemia Observational STudy (MOST) was designed to collect data pertaining to the demographics, clinical management, and patient-reported outcomes in patients with myelofibrosis or ET in the United States (NCT02953704). This analysis examines the clinical characteristics of patients with clinical diagnoses of high-risk or low-risk ET receiving ET-directed therapy at enrollment. At data cutoff (June 17, 2019), 1207 of 1234 enrolled patients were eligible for this analysis (median age, 70 years; 65% female; 88% white); 917 patients (76%) had mutation testing results available. The median time from ET diagnosis to study enrollment was 4.2 years. The majority of patients (87%) had high-risk ET. Of 333 patients with a history of thrombotic events, 247 had at least 1 event classified as arterial and/or venous. Platelet count was above normal range in 54% of patients. Hypertension (56%) was the most common comorbidity. At enrollment, the majority of patients (low-risk ET, 94%; high-risk ET, 79%) were receiving ET-directed monotherapy. Additional prospective analyses from MOST will help to identify areas of unmet need.

Myeloproliferative neoplasms and pregnancy: Overview and practice recommendations

Pregnancy in the context of myeloproliferative neoplasms (MPN) poses unique fetal and maternal challenges. Current literature in this regard mostly involves essential thrombocythemia (ET) and less so polycythemia vera (PV) or myelofibrosis. In ET, live birth rate is estimated at 70% with first trimester fetal loss (˜ 30%) as the major complication. Risk of pregnancy-associated complications is higher in PV, thus mandating a more aggressive treatment approach. Herein, we appraise the relevant literature, share our own experience and propose management recommendations. Aspirin therapy may offer protection against fetal loss; however the additive benefit of systemic anticoagulation or cytoreductive therapy, in the absence of high risk disease, is unclear. We recommend cytoreductive therapy in the form of interferon alpha in all high risk and select low-risk ET and PV patients with history of recurrent fetal loss, prominent splenomegaly or suboptimal hematocrit control with phlebotomy. In addition, all women with PV should maintain strict hematocrit control <45% with the aid of phlebotomy. Systemic anticoagulation with low molecular weight heparin is advised in patients with history of venous thrombosis. Further clarification awaits prospective clinical trials that implement risk adapted therapeutic interventions.

Prevention and Management of Thrombosis in BCR/ABL-Negative Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPNs) are clonal disorders of the hematopoietic stem cell. Classical BCR/ABL-negative MPNs include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). Thrombotic events are a major cause of morbidity and mortality in these patients. Pathogenesis of blood clotting activation involves various abnormalities of platelets, erythrocytes, and leukocytes, as well as dysfunctions of endothelial cells. Patients with MPN can be stratified in "high risk" or "low risk" of thrombosis according to established risk factors. ET and PV clinical management is highly dependent on the patient's thrombotic risk, and a risk-oriented management strategy to treat these diseases is strongly recommended. In this review, we give an overview of risk factors, pathogenesis, and thrombosis prevention and treatment in MPN.

Esssential thrombocythaemia and pregnancy-A need for prospective study and a consensus on its management

MPN are rare diseases, however young women with ET are increasingly being recognised. Management during pregnancy is often a recognised issue with no clear guidelines for management. Pregnancy is associated with considerable risk of complications and therefore warrants a multidisciplinary approach and early identification of high-risk pregnancies. Robust data is limited and therefore we advocate for more prospective (cohort and registry), multicentre, collaborative efforts to gather meaningful information about risk, and risk-adapted therapy, to guide management. The commentary reviews the study by How et al and compares the observations to other studies around the world. It recognises that previous pregnancies with complications increase the risk of further complications during future pregnancies. It is important to recognise the high-risk pregnancies and have a risk adapted approach to the same. The use of low dose aspirin is recommended throughout the pregnancy. The use of LMWH prophylaxis antepartum should be individualised to the thrombotic risk status and applied post-partum for at least 6 weeks. Interferon a remains the safest and effective approach for cytoreductive therapy. Collaborative expert efforts world-wide, as well as larger prospective trials and registry data, will enhance our knowledge to formulate standard guidelines for these group of patients.

Hemorrhage in Essential Thrombocythemia or Polycythemia Vera: Epidemiology, Location, Risk Factors, and Lessons Learned from the Literature

Hemorrhage is a well-known complication of essential thrombocythemia (ET) and polycythemia vera (PV), but evidence-based data on its management and prevention are lacking to help inform clinicians. In this review, appropriate published data from the past 15 years regarding bleeding epidemiology, classification, location, and risk factors are presented and discussed. Research was conducted using the Medline database. The bleeding classifications were heterogeneous among the collected studies. The median incidences of bleeding and major bleeding were 4.6 and 0.79% patients/year, in ET patients and 6.5 and 1.05% patients/year in PV patients, respectively. The most frequent location was the gastrointestinal tract. Bleeding accounted for up to 13.7% of deaths, and cerebral bleeding was the main cause of lethal hemorrhage. Thirty-nine potential risk factors were analyzed at least once, but the results were discrepant. Among them, age >60 years, bleeding history, splenomegaly, myeloproliferative neoplasm subtype, and platelet count should deserve more attention in future studies. Among the treatments, aspirin seemed to be problematic for young patients with ET (especially CALR-mutated ET patients) and anagrelide was also identified as a bleeding inducer, especially when associated with aspirin. Future studies should analyze bleeding risk factors in more homogeneous populations and with common bleeding classifications. More tools are needed to help clinicians manage the increased risk of potentially lethal bleeding events in these diseases.

Acute Myocardial Infarction in an Adolescent Receiving Anagrelide for Essential Thrombocythemia with Underlying Persistent Coronary Endothelial Dysfunction

Essential thrombocythemia (ET) is a Philadelphia chromosome-negative myeloproliferative disorder that is characterized by the overproduction of platelets and a marked increase in the numbers of mature megakaryocytes present in the bone marrow. Thrombohemorrhagic disorders are major morbidities of ET, especially those with mutations in the gene encoding Janus kinase 2 (JAK2). In this study, we report the case of an 18-year-old patient with ET carrying JAK2 mutation who developed acute ST-elevation myocardial infarction (STEMI) 5 months after a commencement of anagrelide. Coronary endothelial dysfunction confirmed by positive acetylcholine provocation test lasted a year after the occurrence of STEMI. Furthermore, intracoronary imaging using optical coherence tomography demonstrated non-atheromatous intimal fibrosis possibly due to chronic endothelial damage. The coronary pathologies reflected chronic change potentially associated with properties of ET and JAK2 mutation in addition to hyperviscosity. These observations suggest that the side effect of anagrelide in our patient was considered causative, while underlying chronic endothelial dysfunction and adverse endothelial remodeling may be predisposing factors to his fatal cardiovascular events.

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

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

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

BACKGROUND AND AIMS

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

From Budd-Chiari syndrome to acquired von Willebrand syndrome: thrombosis and bleeding complications in the myeloproliferative neoplasms

Thrombotic and hemorrhagic complications are prevalent in patients with essential thrombocythemia, polycythemia vera, and myelofibrosis. Given the impact on morbidity and mortality, reducing the risk of thrombosis and/or hemorrhage is a major therapeutic goal. Historically, patients have been risk stratified on the basis of traditional factors, such as advanced age and thrombosis history. However, multiple factors contribute to the thrombotic tendency, including gender, mutational profile, inflammatory stress, and abnormal cell adhesion. Management includes cardiovascular risk reduction and use of antiplatelet therapy, depending on myeloproliferative neoplasm subtype and mutational status. Anticoagulation is a mainstay of therapy for those with venous thrombosis, but practice patterns remain heterogeneous. Cytoreduction is indicated for higher-risk patients, but efficacy may depend on the involved vascular bed. Management of special situations, such as unusual site thrombosis, bleeding, the perioperative period, and pregnancy, are especially challenging. In this article, risk factors and treatment strategies for myeloproliferative neoplasm thrombosis and bleeding, including special situations, are reviewed. Insights gained from recent studies may lead to the development of a more precise risk classification and tailored therapy.

How we manage Philadelphia-negative myeloproliferative neoplasms in pregnancy

The combined incidence of classical Philadelphia-negative myeloproliferative neoplasm (MPN) is 6-9/100 000 with a peak frequency between 50 and 70 years. MPN is less frequent in women of reproductive age. However, for essential thrombocythaemia (ET) in particular there is a second peak in women of reproductive age and 15% of polycythaemia vera (PV) patients are less than 40 years of age at the time of diagnosis. Thus these diseases are encountered in women of reproductive potential and may be diagnosed in pregnancy or in women being investigated for recurrent pregnancy loss. The incidence of MPN pregnancies is 3·2/100 000 maternities per year in the UK. The majority of data regarding Philadelphia-negative MPNs relates to patients with ET, for which the literature suggests significant maternal morbidity and poor fetal outcome; specifically maternal thrombosis and haemorrhage, miscarriage, pre-eclampsia, intrauterine growth restriction (IUGR), stillbirth and premature delivery as summarised in the recent systematic review and meta-analysis in Blood, 2018, 132, 3046. The literature for PV is more sparse but increasing and is concordant with ET pregnancy outcomes. The literature regarding primary myelofibrosis (PMF) is even more scarce. Treatment options include aspirin, venesection, low molecular weight heparin (LMWH) and cytoreductive therapy. Data and management recommendations are often extrapolated from other pro-thrombotic conditions or from ET to PV and PMF. Women of reproductive age with a diagnosis of MPN should receive information and assurance regarding management and outcome of future pregnancies. From pre-conceptual planning to the post-partum period, women should have access to joint care from an obstetrician with experience of high-risk pregnancies and a haematologist in a multidisciplinary setting. This paper provides an update with regards to Philadelphia-negative MPN in pregnancy, details local practise in an internationally recognised centre for patients with MPN and outlines a future research strategy.

The new WHO classification for essential thrombocythemia calls for revision of available evidences

In the 2016 revised classification of myeloproliferative neoplasms pre-fibrotic primary myelofibrosis (pre-PMF) was recognized as a separate entity, distinct from essential thrombocythemia (ET). Owing that the majority of cases falling in the pre-PMF category were previously diagnosed as ET, one may question about the need to re-evaluate the results of epidemiologic, clinical, and molecular studies, and the results of clinical trials in the two entities. Based on a critical review of recently published studies, pre-PMF usually presents with a distinct clinical and hematological presentation and higher frequency of constitutional symptoms. JAK2V617F and CALR mutations in pre-PMF patients are superimposable to ET, whereas non-driver high-risk mutations are enriched in pre-PMF compared with ET. Thrombosis is not significantly different, whereas bleeding is more frequent in pre-PMF. Median survival is significantly shorter in pre-PMF and 10-year cumulative rates progression to overt myelofibrosis is 0-1% vs. 10-12%, and leukemic transformation is 1-2% vs. 2-6%, in ET and pre-fibrotic-PMF, respectively. Most patients fall in the lower prognostic IPSS group in which observation alone can be recommended. Patients at intermediate risk may require a symptom-driven treatment for anemia, splenomegaly or constitutional symptoms while cytoreductive drugs are indicated in the high-risk category.

"Anagrelide-induced pulmonary arterial hypertension": a rare case of drug-induced pulmonary arterial hypertension

Pulmonary arterial hypertension can be associated with exposure to certain drugs or toxins. However, only a few cases of drug-induced pulmonary arterial hypertension have been previously reported. Anagrelide is an oral imidazoquinazoline agent that is prescribed for reducing elevated platelet counts in patients with myeloproliferative disorders. We report the case of a 70-year-old female patient who developed pulmonary arterial hypertension after taking anagrelide for the treatment of polycythemia vera. Pulmonary arterial hypertension promptly improved after the discontinuation of anagrelide. Anagrelide-induced pulmonary arterial hypertension is a very rare disease, and our case shows that it might be reversible.

From Budd-Chiari syndrome to acquired von Willebrand syndrome: thrombosis and bleeding complications in the myeloproliferative neoplasms

Thrombotic and hemorrhagic complications are prevalent in patients with essential thrombocythemia, polycythemia vera, and myelofibrosis. Given the impact on morbidity and mortality, reducing the risk of thrombosis and/or hemorrhage is a major therapeutic goal. Historically, patients have been risk stratified on the basis of traditional factors, such as advanced age and thrombosis history. However, multiple factors contribute to the thrombotic tendency, including gender, mutational profile, inflammatory stress, and abnormal cell adhesion. Management includes cardiovascular risk reduction and use of antiplatelet therapy, depending on myeloproliferative neoplasm subtype and mutational status. Anticoagulation is a mainstay of therapy for those with venous thrombosis, but practice patterns remain heterogeneous. Cytoreduction is indicated for higher-risk patients, but efficacy may depend on the involved vascular bed. Management of special situations, such as unusual site thrombosis, bleeding, the perioperative period, and pregnancy, are especially challenging. In this article, risk factors and treatment strategies for myeloproliferative neoplasm thrombosis and bleeding, including special situations, are reviewed. Insights gained from recent studies may lead to the development of a more precise risk classification and tailored therapy.

Association of Treatments for Myeloproliferative Neoplasms During Pregnancy With Birth Rates and Maternal Outcomes: A Systematic Review and Meta-analysis

Importance

Myeloproliferative neoplasms (MPNs) are increasingly being identified in women of childbearing potential. Pregnancy in women with MPNs is associated with maternal thrombosis, hemorrhage, and placental dysfunction leading to fetal growth restriction or loss.

Objective

To evaluate the association between the use of aspirin, heparin, interferon, or combinations and live birth rate and adverse maternal outcomes in pregnant women with MPNs.

Data Sources

Systematic searches of MEDLINE, Embase, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, and the MEDLINE Epub Ahead of Print and In-Process and Other Non-Indexed Citations from inception to July 19, 2018, with no language restrictions, was conducted. Key search terms included myeloproliferative disorders, polycythemia vera, essential thrombocythemia, and primary myelofibrosis.

Study Selection

A study was eligible if it included pregnant patients with MPNs; interventions included aspirin, heparin, and/or interferon; there was a comparison group in which patients did not receive the intervention; the study reported on at least 1 of the study outcomes; and it was a randomized, case-control, or cohort study or series of at least 10 pregnancies. Data were extracted in duplicate; 0.5% of identified studies met selection criteria.

Data Extraction and Synthesis

The review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines and reported in accordance with Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines. Data were pooled using the Mantel-Haenszel approach.

Main Outcomes and Measures

Outcomes were the number of live births and maternal complications, specifically, arterial or venous thrombosis, hemorrhage, and preeclampsia.

Results

Twenty-two studies reporting on 1210 pregnancies were included. The live birth rate was 71.3% (95% CI, 65.1%-77.6%). Use of aspirin (11 studies, 227 patients; unadjusted odds ratio, 8.6; 95% CI, 4.0-18.1) and interferon (6 studies, 90 patients; unadjusted odds ratio, 9.7; 95% CI, 2.3-41.0) were associated with higher odds of live birth. Addition of heparin to aspirin was not associated with higher odds of live birth (6 studies, 96 patients; unadjusted odds ratio, 2.1; 95% CI, 0.5-9.0). The most common adverse maternal event was preeclampsia, with an incidence of 3.1% (95% CI, 1.7%-4.5%).

Conclusions and Relevance

Most studies reported on pregnancy with essential thrombocythemia. Few studies reported on pregnancy with polycythemia vera and none with myelofibrosis met the inclusion criteria. Most studies were retrospective and early pregnancy losses may have been underreported. Moderate-quality evidence suggests that aspirin or interferon is associated with higher odds of live birth in pregnant women with MPN.

Efficacy and safety of anagrelide as a first-line drug in cytoreductive treatment-naïve essential thrombocythemia patients in a real-world setting

Objective

This study aimed to retrospectively assess the efficacy and safety of anagrelide in cytoreduction therapy‐naïve essential thrombocythemia (ET) patients in a real‐world setting.

Method

Data from 53 ET patients who received anagrelide as a first‐line therapy were reviewed for patient characteristics, antiplatelet status, cytoreduction status, therapeutic effects, adverse events, thrombohemorrhagic event development, progression to myelofibrosis or acute leukemia, and cause of death.

Results

The rate of achieving a platelet count of <600 × 10⁹/L during anagrelide monotherapy was 83.0%. Adverse events occurred in 32 of 53 patients, and tended to be slightly more severe in patients with cardiac failure; however, they were mostly tolerable. The therapeutic effect of anagrelide was consistent, regardless of genetic mutation profiles. The incidence of anemia as an adverse event was significantly higher in the CALR mutation‐positive group. Favorable platelet counts were also achieved in patients for whom hydroxyurea was introduced as a replacement for anagrelide or in addition to anagrelide because of unresponsiveness or intolerance to treatment.

Conclusion

In Japanese cytoreduction therapy‐naïve ET patients, anagrelide administration as a first‐line therapy demonstrated favorable effects in reducing platelet counts, and its safety profile that was generally consistent with those in previous reports.

Emerging drugs for essential thrombocythemia

Introduction: Despite our recent progress in the understanding of essential thrombocythemia (ET) pathogenesis, the therapeutic management of this disease has remained largely unchanged in the past decades. Treatment has mostly focused on decreasing the risk of complications, especially prevention of thrombotic or hemorrhagic events. Areas covered: Over recent years, the treatment options of ET have been expanding with some novel agents on the horizon. The classes of agents described in this review include targeted and immunomodulatory agents, such as JAK1/2 inhibitors, interferon-α, histone deacetylase inhibitors, telomerase inhibitors and human double minute 2 inhibitors. These compounds entered various stages of development, albeit the only portion of them is currently actively undergoing evaluation in clinical trials. In this review, we look at the current therapies and discuss novel agents available in the management of ET. Expert opinion: The drug development in ET possesses several challenges stemming from its relatively benign and prolonged disease course. Therapy focused on reducing the risk of thrombotic and hemorrhagic complications and symptom management needs to be chosen wisely as a vast majority of these patients have a near-normal life expectancy. To date, no therapy has shown effective and definitive alteration of the disease behavior. Although novel agents are in development and hopefully some of them will extend treatment armamentarium of ET, their exact role remains to be determined.

Contemporary management of essential thrombocythemia in children

INTRODUCTION

Essential thrombocythemia (ET) is a disease which is extremely rare in children. Only recently, data on pediatric ET have become available. Areas covered: In children with sustained platelet count over 450 x 10⁹/L, secondary thrombocytosis must be ruled out. ET workup comprehends research of JAK2V617F, CALR and MPL mutations and bone marrow biopsy (BM). In asymptomatic children wait and watch is the best option. Aspirin controls headache and other microvascular disturbances. Patients with venous thrombosis need anticoagulation. Cytoreductive drugs in children with ET should be prescribed as a last choice. Hydroxyurea and IFN-a are first-line therapy at any age including children; Anagrelide is not licensed as first-line therapy for ET in Europe. New JAK2-inhibitors are not clearly useful in ET and hence not approved for ET. Expert opinion: The most challenging problem is to understand if a child with prolonged not secondary thrombocytosis really has ET. Diagnostic workup requires molecular and histological studies. The rare children with clonal ET have features like those of adults. Patients with ET have long expected survival and the treatment in children must be long-term efficacious and well tolerated.

Heterogeneity in myeloproliferative neoplasms: Causes and consequences

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

Leukemic transformation and second cancers in 3649 patients with high-risk essential thrombocythemia in the EXELS study

EXELS, a post-marketing observational study, is the largest prospective study of high-risk essential thrombocythemia (ET) patients, with an observation time of 5 years. EXELS found higher event rates of acute leukemia transformation in patients treated with hydroxycarbamide (HC). In the current analysis, we report age-adjusted rates of malignant transformation from 3460 EXELS patients exposed to HC, anagrelide (ANA), or both. At registration, 481 patients had ANA treatment without HC exposure, 2305 had HC without ANA exposure, and 674 had been exposed to both. Standard incidence ratios (SIRs) were calculated using data from the Cancer Incidence in Five Continents database to account for differences in age-, gender-, and country-specific background rates. SIRs for acute myelogenous leukemia (AML) were high in ET patients. SIRs for AML were high in HC-treated patients, but AML was rare in ANA-treated patients; no cases of AML were found in patients only treated with ANA. No statistically significant difference was seen between SIRs for ANA and HC treatment for AML or skin cancer. SIRs for other cancers were similar in the HC and ANA groups and close to 1, indicating little difference in risk. Although statistically inconclusive, this study strengthens concerns regarding possible leukemogenic risk with HC treatment. (NCT00202644).

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

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

Ruxolitinib for the Treatment of Essential Thrombocythemia

Deregulated Janus Kinase 2 (JAK2) activation is central to the pathogenesis of most myeloproliferative neoplasms (MPNs), of which essential thrombocythemia (ET) is the most common entity. Patients with ET are risk-stratified according to their risk of thrombo-hemorrhagic complications. High-risk patients are offered treatments to reduce their platelet count using cytoreductive therapy. The disease course is often long and therapy intolerance is not infrequent. Ruxolitinib, a Janus Kinase (JAK) 1/JAK2 inhibitor, has demonstrated efficacy in patients with both myelofibrosis (MF) and polycythemia vera and is well tolerated. Side effects include predictable cytopenias and an augmented risk of infections. Ruxolitinib has been investigated in a small group of ET patients who were refractory/intolerant to hydroxycarbamide (HC) and demonstrated improvements in both symptoms and splenomegaly. Of note, a proportion of treated patients (13.2%) also had a significant reduction in platelet counts. However, these results require further validation in comparison with conventional therapy. Recently, a randomized-controlled phase 2 study (MAJIC-ET) assessed the role of Ruxolitinib in patients refractory or intolerant to HC. This study revealed that Ruxolitinib demonstrated some clinical efficacy but was only superior in terms of symptom control. In clinical practice, some individuals with ET do exhaust all potential treatment options and there may well be a role for Ruxolitinib in such patients or those with a significant symptom burden. However, in the wider context the goal of therapy with the use of JAK inhibitor therapy in ET needs to be defined carefully and we explore this within this timely review article.