Polycythemia vera-associated acquired von Willebrand syndrome despite near-normal platelet count

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.

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).

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.

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.

Successful Chemical Synovectomy in a Patient with Acquired von Willebrand Syndrome with Chronic Synovitis Due to Recurrent Knee Hemarthrosis: A Case Report

Acquired von Willebrand syndrome (AVWS) is a rare, non-hereditary bleeding disorder related to heterogeneous medical conditions such as hematological malignancies and cardiovascular and autoimmune diseases. We describe the clinical course of a 62-year-old man with polycythemia vera who experienced post-traumatic knee and leg swelling due to hemarthrosis. He was treated at another center with low molecular weight heparin due to misdiagnosed deep vein thrombosis further exacerbating the ongoing bleeding. At our center, he was diagnosed with AVWS with reduced von Willebrand factor (VWF):GPIbR plasma activity and loss of high molecular weight multimers (HMWM). He was treated with compressive bandages with resolution. Five months later, on clinical recurrence of knee and leg swelling, knee ultrasound scan showed the presence of chronic synovitis and a hemorrhagic Baker's cyst with signs of rupture. The treatment consisted of chemical synovectomy with rifampicin and steroids preceded by systemic replacement therapy using plasma-derived factor VIII-VWF concentrate. At the end of the treatment cycle, our patient reported complete resolution of knee pain and restoration of joint range of motion and function. Ultrasound evaluation confirmed complete resolution of knee capsule distension and Baker's cyst. Hemarthrosis is an anecdotal presentation of AVWS and chemical synovectomy was successful in treating this complication. A multidisciplinary approach allowed an effective management of this rare complication.

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

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

Polycythemia vera and essential thrombocythemia: 2021 update on diagnosis, risk-stratification and management

DISEASE OVERVIEW

Polycythemia vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms (MPN) respectively characterized by clonal erythrocytosis and thrombocytosis; other disease features include leukocytosis, splenomegaly, thrombosis, bleeding, microcirculatory symptoms, pruritus and risk of leukemic or fibrotic transformation.

DIAGNOSIS

Bone marrow morphology remains the cornerstone of diagnosis. In addition, the presence of JAK2 mutation is expected in PV while approximately 90% of patients with ET express mutually exclusive JAK2, CALR or MPL mutations (so called driver mutations). In ET, it is most important to exclude the possibility of prefibrotic myelofibrosis.

SURVIVAL

Median survivals are approximately 15 years for PV and 18 years for ET; the corresponding values for patients age 40 or younger were 37 and 35 years. Certain mutations (mostly spliceosome) and abnormal karyotype might compromise survival in PV and ET. Life-expectancy in ET is inferior to the control population. Driver mutations have not been shown to affect survival in ET but risk of thrombosis is higher in JAK2 mutated cases. Leukemic transformation rates at 10 years are estimated at <1% for ET and 3% for PV.

THROMBOSIS RISK

In PV, two risk categories are considered: high (age > 60 years or thrombosis history present) and low (absence of both risk factors). In ET, 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 (age > 60 years, no thrombosis history, JAK2 wild-type) and high (thrombosis history present or age > 60 years with JAK2 mutation).

RISK-ADAPTED THERAPY

The main goal of therapy in both PV and ET is to prevent thrombohemorrhagic complications. All patients with PV require phlebotomy to keep hematocrit below 45% and once-daily or twice-daily aspirin (81 mg), in the absence of contraindications. Very low risk ET might not require therapy while aspirin therapy is advised for low risk disease. Cytoreductive therapy is recommended for high-risk ET and PV, but it is not mandatory for intermediate-risk ET. First-line drug of choice for cytoreductive therapy, in both ET and PV, is hydroxyurea and second-line drugs of choice are interferon-α and busulfan. We do not recommend treatment with ruxolutinib in PV, unless in the presence of severe and protracted pruritus or marked splenomegaly that is not responding to the aforementioned drugs.

NEW TREATMENT DIRECTIONS

Controlled studies are needed to confirm the clinical outcome value of twice-daily vs once-daily aspirin dosing and the therapeutic role of pegylated interferons and direct oral anticoagulants.

Essential Thrombocythemia and Acquired von Willebrand Syndrome: The Shadowlands between Thrombosis and Bleeding

Over the past decade, new insights have emerged on the pathophysiology of essential thrombocythemia (ET), its clinical management, and associated thrombohemostatic disturbances. Here, we review the latest diagnostic and risk stratification modalities of ET and its therapeutics. Moreover, we discuss the clinical evidence-based benefits, deriving from major clinical trials, of using cytoreductive therapy and antiplatelet agents to lower the risk of fatal vascular events. Also, we focus on the condition of extreme thrombocytosis (>1000 × 10⁹/L) and bleeding risk, the development and pathogenesis of acquired von Willebrand syndrome, and the clinical approach to this paradoxical scenario in ET.

Polycythemia vera and essential thrombocythemia: 2019 update on diagnosis, risk-stratification and management

Disease Overview: Polycythemia vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms respectively characterized by erythrocytosis and thrombocytosis; other disease features include leukocytosis, splenomegaly, thrombosis, bleeding, microcirculatory symptoms, pruritus, and risk of leukemic or fibrotic transformation. Diagnosis: Bone marrow morphology remains the cornerstone of diagnosis. In addition, the presence of JAK2 mutation is expected in PV while approximately 90% of patients with ET express mutually exclusive JAK2, CALR, or myeloproliferative leukemia mutations. In ET, it is most important to exclude the possibility of prefibrotic myelofibrosis. Survival: Median survivals are 14 years for PV and 20 years for ET; the corresponding values for younger patients are 24 and 33 years. Certain mutations (mostly spliceosome) and abnormal karyotype might compromise survival in PV and ET. Life-expectancy in ET is inferior to the control population. Driver mutations have not been shown to affect survival in ET. Risk of thrombosis is higher in JAK2-mutated ET. Leukemic transformation rates at 10 years are estimated at <1% for ET and 3% for PV. Thrombosis Risk: In PV, 2 risk categories are considered: high (age > 60 years or thrombosis history present) and low (absence of both risk factors); in ET, 4 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 (age > 60 years, no thrombosis history, JAK2 wild-type) and high (thrombosis history present or age > 60 years with JAK2 mutation). Risk-Adapted Therapy: The main goal of therapy in both PV and ET is to prevent thrombohemorrhagic complications. All patients with PV require phlebotomy to keep hematocrit below 45% and once- or twice-daily aspirin (81 mg), in the absence of contraindications. Very low-risk ET might not require therapy while aspirin therapy is advised for low-risk disease. Cytoreductive therapy is recommended for high-risk ET and PV but it is not mandatory for intermediate-risk ET. First-line drug of choice for cytoreductive therapy, in both ET and PV, is hydroxyurea and second-line drugs of choice are interferon-α and busulfan. We do not recommend treatment with ruxolutinib in PV, unless in the presence of severe and protracted pruritus or marked splenomegaly that is not responding to the aforementioned drugs.

Philadelphia chromosome-negative classical myeloproliferative neoplasms: revised management recommendations from European LeukemiaNet

This document updates the recommendations on the management of Philadelphia chromosome-negative myeloproliferative neoplasms (Ph-neg MPNs) published in 2011 by the European LeukemiaNet (ELN) consortium. Recommendations were produced by multiple-step formalized procedures of group discussion. A critical appraisal of evidence by using Grades of Recommendation, Assessment, Development and Evaluation (GRADE) methodology was performed in the areas where at least one randomized clinical trial was published. Seven randomized controlled trials provided the evidence base; earlier phase trials also informed recommendation development. Key differences from the 2011 diagnostic recommendations included: lower threshold values for hemoglobin and hematocrit and bone marrow examination for diagnosis of polycythemia vera (PV), according to the revised WHO criteria; the search for complementary clonal markers, such as ASXL1, EZH2, IDH1/IDH2, and SRSF2 for the diagnosis of myelofibrosis (MF) in patients who test negative for JAK2V617, CALR or MPL driver mutations. Regarding key differences of therapy recommendations, both recombinant interferon alpha and the JAK1/JAK2 inhibitor ruxolitinib are recommended as second-line therapies for PV patients who are intolerant or have inadequate response to hydroxyurea. Ruxolitinib is recommended as first-line approach for MF-associated splenomegaly in patients with intermediate-2 or high-risk disease; in case of intermediate-1 disease, ruxolitinib is recommended in highly symptomatic splenomegaly. Allogeneic stem cell transplantation is recommended for transplant-eligible MF patients with high or intermediate-2 risk score. Allogeneic stem cell transplantation is also recommended for transplant-eligible MF patients with intermediate-1 risk score who present with either refractory, transfusion-dependent anemia, blasts in peripheral blood > 2%, adverse cytogenetics, or high-risk mutations. In these situations, the transplant procedure should be performed in a controlled setting.

Factors related to the development of acquired von Willebrand syndrome in patients with essential thrombocythemia and polycythemia vera

OBJECTIVE

We characterized acquired von Willebrand syndrome (AVWS) among essential thrombocythemia (ET) and polycythemia vera (PV) patients.

METHODS

A review of patients with ET or PV evaluated for AVWS.

RESULTS

Of 116 patients with ET, 64 (55%) developed AVWS; of 57 with PV, 28 (49%) developed AVWS. Median platelet counts of ET and PV patients who developed AVWS were 920×10⁹/L and 679×10⁹/L, respectively (P=0.01). Of patients who developed AVWS, 69.5% had platelet counts below 1000×10⁹/L. Bleeding was more common in patients with AVWS, among both ET and PV patients (P<0.001). VWF:RCo levels and VWF:RCo/VWF:Ag ratio were lower among JAK2 V617F positive- vs. JAK2 V617F negative- ET patients (P=0.02 and P=0.002, respectively); whereas VWF:Ag levels were comparable (P=0.96). ET patients harboring the JAK2 V617F mutation were more likely to develop AVWS than were calreticulin-positive patients (70.3% vs. 45.7%, P=0.02), despite lower platelet counts (median 773 vs. 920×10⁹/L, P=0.05). In multivariable analysis, younger age (P=0.002), platelet count (P<0.001), hemoglobin level (P=0.01) and JAK2 V617F mutation (P=0.01) independently predicted the development of AVWS among ET patients; whereas only platelet count predicted its development among PV patients (P<0.001).

CONCLUSION

Among ET and PV patients, AVWS was common and associated with higher bleeding rates and higher platelet count; nonetheless, most AVWS patients had platelet counts under 1000×10⁹/L. Thus, AVWS screening should be included in routine assessment of ET and PV patients. Among ET patients, JAK2 V617F was a main driver for the development of AVWS.

Polycythemia vera and essential thrombocythemia: 2017 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Polycythemia Vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms respectively characterized by erythrocytosis and thrombocytosis; other disease features include leukocytosis, splenomegaly, thrombosis, bleeding, microcirculatory symptoms, pruritus, and risk of leukemic or fibrotic transformation.

DIAGNOSIS

PV is defined by a JAK2 mutation, whose absence, combined with normal or increased serum erythropoietin level, makes the diagnosis unlikely. JAK2, CALR, and MPL mutations are the mutually exclusive "driver" mutations in ET with respective incidences of 55%, 25%, and 3%; approximately 17% are triple-negative. However, the same molecular markers might also be present in prefibrotic myelofibrosis, whose morphological distinction from ET is prognostically relevant.

SURVIVAL AND LEUKEMIC/FIBROTIC TRANSFORMATION

Median survivals are approximately 14 years for PV and 20 years for ET; the corresponding values for younger patients (age <60 years) are 24 and 33 years. Life-expectancy in ET is inferior to the control population. Driver mutational status has not been shown to affect survival in ET whereas the presence of JAK2/MPL mutations has been associated with higher risk of arterial thrombosis and that of MPL with higher risk of fibrotic progression. Risk factors for overall survival in both ET and PV include advanced age, leukocytosis and thrombosis. Leukemic transformation rates at 20 years are estimated at <10% for PV and 5% for ET; fibrotic transformation rates are slightly higher. Most recently, ASXL1, SRSF2, and IDH2 mutations have been associated with inferior overall, leukemia-free or fibrosis-free survival in PV; similarly adverse mutations in ET included SH2B3, SF3B1, U2AF1, TP53, IDH2, and EZH2.

THROMBOSIS RISK STRATIFICATION

Current risk stratification in PV and ET is designed to estimate the likelihood of recurrent thrombosis. Accordingly, PV includes two risk categories: high-risk (age >60 years or thrombosis history) and low-risk (absence of both risk factors). In ET, risk stratification includes four categories: very low risk (age ≤60 years, no thrombosis history, JAK2/MPL un-mutated), low risk (age ≤60 years, no thrombosis history, JAK2/MPL mutated), intermediate risk (age >60 years, no thrombosis history, JAK2/MPL un-mutated), and high risk (thrombosis history or age >60 years with JAK2/MPL mutation). In addition, presence of extreme thrombocytosis (platelets >1000 × 10(9)/L) might be associated with acquired von Willebrand syndrome (AvWS) and, therefore, risk of bleeding.

RISK-ADAPTED THERAPY

The main goal of therapy in PV and ET is to prevent thrombohemorrhagic complications. All patients with PV require phlebotomy to keep hematocrit below 45% and once-daily aspirin (81 mg). In addition, high-risk patients with PV require cytoreductive therapy. Very low risk ET patients might not require any form of therapy while low-risk patients require at least once-daily aspirin therapy. Cytoreductive therapy is also recommended for high-risk ET patients but it is not mandatory for intermediate-risk patients. First-line drug of choice for cytoreductive therapy, in both ET and PV, is hydroxyurea and second-line drugs of choice are interferon-α and busulfan. We currently do not recommend treatment with ruxolutinib or other JAK2 inhibitors in PV or ET, unless in the presence of severe and protracted pruritus or marked splenomegaly that is not responding to the aforementioned drugs. Screening for AvWS is recommended before administrating aspirin, in the presence of extreme thrombocytosis. Am. J. Hematol. 92:95-108, 2017. © 2016 Wiley Periodicals, Inc.

Laboratory Investigation of Myeloproliferative Neoplasms (MPNs): Recommendations of the Canadian Mpn Group

OBJECTIVES

To standardize diagnostic investigations for myeloproliferative neoplasms (MPNs) to increase homogeneity in patient care and to streamline diagnostic approaches in the most efficient and cost-effective manner.

METHODS

The development of Canadian expert consensus recommendations for the diagnosis of MPNs began with a review of the following: clinical evidence, daily practice, existing treatment guidelines, and availability of diagnostic tools. Each group member was assigned a specific topic, which they discussed with the entire group during several consensus meetings.

RESULTS

This document provides the Canadian MPN group's recommendations, proposed diagnostic algorithms, and background evidence upon which decisions were made.

CONCLUSIONS

Standardization of diagnostic investigations will increase homogeneity in patient care and provide a foundation for future clinical research in this rapidly evolving therapeutic area. Streamlining diagnostic approaches in the most efficient and cost-effective manner will also result in significant cost saving for the health care system.

Diagnosis, prevention, and management of bleeding episodes in Philadelphia-negative myeloproliferative neoplasms: recommendations by the Hemostasis Working Party of the German Society of Hematology and Medical Oncology (DGHO) and the Society of Thrombosis and Hemostasis Research (GTH)

Philadelphia-negative myeloproliferative neoplasms (Ph-negative MPN) comprise a heterogeneous group of chronic hematologic malignancies. The quality of life, morbidity, and mortality of patients with MPN are primarily affected by disease-related symptoms, thromboembolic and hemorrhagic complications, and progression to myelofibrosis and acute leukemia. Major bleeding represents a common and important complication in MPN, and the incidence of such bleeding events will become even more relevant in the future due to the increasing disease prevalence and survival of MPN patients. This review discusses the causes, differential diagnoses, prevention, and management of bleeding episodes in patients with MPN, aiming at defining updated standards of care in these often challenging situations.

Pharmacoeconomics of ruxolitinib therapy in patients with myelofibrosis

BACKGROUND

Overall survival (OS) and other important clinical trial end-points seem increasingly more elusive in supporting rapid and efficient incorporation of innovative cancer drugs in clinical practice. This study proposes a clinical trial based pharmacoeconomic framework to assess the therapeutic and economic value of ruxolitinib in patients with intermediate-2 or high-risk myelofibrosis.

METHODS

Individual patient level 144 week follow-up data from the COMFORT-II trial was used to account for the crossover effect on overall survival. Lifetime treatment benefits and costs were estimated considering detailed patterns of both ruxolitinib dose adjustments and blood transfusion needs.

RESULTS

The authors estimate a 3.3 years increment in life expectancy (HR = 0.30; 95% CI = 0.17-0.55; p-value <0.001) and an incremental cost-effectiveness ratio of €40,000 per life year gained with the use of ruxolitinib.

CONCLUSION

This study also demonstrates how valuable information from clinical trials can be used to support informed decisions about the early incorporation of innovative drugs.

Management of side effects of BCR/ABL-negative chronic myeloproliferative neoplasm therapies. Focus on anagrelide

Although hydroxyurea is considered the first-line cytoreductive therapy in high-risk patients with polycythemia vera or essential thrombocythemia, approximately 20-25% of patients develop resistance or intolerance and they need an alternative therapy. Anagrelide is the treatment of choice in patients with essential thrombocythemia intolerant or with resistance to hydroxyurea. Anagrelide is usually well tolerated. Although there is concern about the increased risk of cardiac side effects, in most cases these are mild, and easily manageable. In this paper, the available evidence about the management of patients with myeloproliferative neoplasms, with a special focus on the side effects of drug therapies is reviewed.

Acquired von Willebrand syndrome in a case of polycythemia vera resulting in recurrent and massive bleeding events in the pleural and abdominal cavity

A 52-year-old woman was admitted to the hospital three times in a span of 5 years in hypovolemic shock because of spontaneous and massive bleeding in the pleural and abdominal cavity. Blood tests revealed a high number of blood cells, and bone marrow smears showed trilineage myeloproliferation. Serum erythropoietin level was decreased. Analysis revealed a V617F mutation in the JAK2 protein. Her activated partial thromboplastin time was slightly prolonged, the ratio between von Willebrand factor (vWF) propeptide and vWF antigen was in the normal range, but the ratio between vWF and ristocetin cofactor was decreased dramatically. Further investigation revealed the absence of large and intermediate vWF-multimers. She was diagnosed with polycythemia vera with acquired von Willebrand syndrome. The bleeding was stopped using a transfusion of freshly thawed plasma and cryoprecipitate.

A review on thromboangiitis obliterans pathophysiology: thrombosis and angiitis, which is to blame?

A century has passed since thromboangiitis obliterans (TAO), or Buerger's disease, was first described, but the etiology remains unclear. It is still uncertain as to whether thrombosis or vascular inflammation is the first event. TAO is an episodic inflammatory and thrombotic-occlusive vascular disease of unknown origin. The involvement of the distal vessels and nerves within the neuro-vascular bundles occurs almost always in legs and occasionally in arms. The cumulative data demonstrate that at the cellular and molecular levels, at least four main components of inflammatory reactions, including endothelial cells, platelets, leukocytes and sensory neurons, might be involved in TAO pathogenesis. The interactions among these cells in an altered microenvironment of small- and medium-sized vessels may also orchestrate the onset of TAO events. In this review, the factors that may promote thrombosis and angiitis are reconsidered at three levels: (1) host characteristics such as male gender and genetic background; (2) probable triggers including cigarette smoking and infectious agents; and (3) environmental factors such as chronic anxiety and mental stress as a consequence of low socioeconomic status. At each level, the interactions among vascular endothelium, platelets, leukocytes and sensory neurons are discussed.

Polycythemia vera and essential thrombocythemia: 2015 update on diagnosis, risk-stratification and management

DISEASE OVERVIEW

Polycythemia vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms, respectively characterized by erythrocytosis and thrombocytosis. Other disease features include leukocytosis, splenomegaly, thrombosis, bleeding, microcirculatory symptoms, pruritus, and risk of leukemic or fibrotic transformation.

DIAGNOSIS

PV is defined by a JAK2 mutation, whose absence, combined with normal or increased serum erythropoietin level, makes the diagnosis unlikely. Differential diagnosis in ET includes reactive thrombocytosis, chronic myeloid leukemia, and prefibrotic myelofibrosis. Janus kinase 2 (JAK2), calreticulin (CALR), or myeloproliferative leukemia virus oncogene (MPL) mutations occur in approximately 55%, 25%, and 3% of ET patients, respectively. The same molecular markers are also present in prefibrotic myelofibrosis, which needs to be morphologically distinguished from ET. Survival and leukemic/fibrotic transformation: Median survivals are ∼14 years for PV and 20 years for ET; the corresponding values for younger patients are 24 and 33 years. Life-expectancy in ET is inferior to the control population. JAK2/CALR mutational status does not affect survival in ET. Risk factors for survival in ET and PV include advanced age, leukocytosis, and thrombosis. Leukemic transformation rates at 20 years are estimated at <10% for PV and 5% for ET; fibrotic transformation rates are slightly higher. Thrombosis risk stratification: Current risk stratification in PV and ET is designed to estimate the likelihood of recurrent thrombosis: high-risk is defined by the presence of age >60 years or presence of thrombosis history; low-risk is defined by the absence of both of these two risk factors. Recent data consider JAK2V617F and cardiovascular risk factors as additional risk factors. Presence of extreme thrombocytosis might be associated with acquired von Willebrand syndrome (AvWS) and, therefore, risk of bleeding.

RISK-ADAPTED THERAPY

The main goal of therapy in PV and ET is to prevent thrombohemorrhagic complications. In low risk patients, this is accomplished by the use of low-dose aspirin and phlebotomy (hematocrit target <45%) in PV. In high risk (for thrombosis) patients, treatment with hydroxyurea is additionally recommended. Treatment with busulfan or interferon-α is usually effective in hydroxyurea failures and the additional value of JAK inhibitor therapy in such cases is limited. Screening for AvWS is recommended before administrating aspirin, in the presence of extreme thrombocytosis.

How I treat polycythemia vera

Polycythemia vera (PV) is a chronic myeloproliferative neoplasm associated with JAK2 mutations (V617F or exon 12) in almost all cases. The World Health Organization has defined the criteria for diagnosis, but it is still unclear which parameter (hemoglobin or hematocrit) is the most reliable for demonstrating increased red cell volume and for monitoring response to therapy; also, the role of bone marrow biopsy is being revisited. PV is associated with reduced survival because of cardiovascular complications and progression to post-PV myelofibrosis or leukemia. Criteria for risk-adapted treatment rely on the likelihood of thrombosis. Controlled trials have demonstrated that incidence of cardiovascular events is reduced by sustained control of hematocrit with phlebotomies (low-risk patients) and/or cytotoxic agents (high-risk patients) and antiplatelet therapy with aspirin. Hydroxyurea and interferon may be used as first-line treatments, whereas busulfan is reserved for patients that are refractory or resistant to first-line agents. However, there is no evidence that therapy improves survival, and the significance of reduction of JAK2 mutated allele burden produced by interferon is unknown. PV is also associated with a plethora of symptoms that are poorly controlled by conventional therapy. This article summarizes my approach to the management of PV in daily clinical practice.

Target hematologic values in the management of essential thrombocythemia and polycythemia vera

Treatment of essential thrombocythemia (ET) and polycythemia vera (PV) is aimed at preventing vascular complications, which are the main cause of morbidity and mortality in these diseases. Over the years, clinical trials have demonstrated that the incidence of thrombosis and bleeding can be reduced by controlling the blood cell counts, but the target hematological levels have varied across the studies. In this article, we review the evidence supporting the use of predefined target hematologic values for the management of ET and PV in routine clinical practice. At present, the recommended target hematocrit in PV is below 45%, regardless of the patients' risk profile. Concerning platelet counts, no direct correlation has been demonstrated with thrombotic risk in either ET or PV. Thus, although cytoreductive treatment reduces the rate of vascular complications in high-risk patients, no particular threshold of the platelet counts has been shown to be more protective against thrombosis. Extreme thrombocytosis is a risk factor for bleeding, particularly when aspirin or anagrelide are given. Leukocytosis at baseline or during follow-up appears to be a risk factor for thrombosis, mostly in high-risk patients. However, the clinical benefit of strictly controlling this parameter is not yet established. Finally, standardized definitions of response to cytoreductive treatment in ET and PV have recently been published. Nevertheless, they have been produced to compare the efficacy of new therapies in clinical trials, whereas its relevance in clinical practice has been questioned in retrospective studies showing that such response definitions do not correlate with the patients' clinical outcome.

Polycythemia vera and essential thrombocythemia: 2013 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Polycythemia Vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms (MPN) primarily characterized by erythrocytosis and thrombocytosis, respectively. Other disease features include leukocytosis, splenomegaly, thrombohemorrhagic complications, vasomotor disturbances, pruritus and a small risk of disease progression into acute myeloid leukemia or myelofibrosis.

DIAGNOSIS

Almost all patients with PV harbor a JAK2 mutation. When PV is suspected, the presence of a JAK2 mutation highly suggests the diagnosis and its absence, combined with normal or increased serum erythropoietin level, excludes the diagnosis. Differential diagnosis of ET should include reactive thrombocytosis, chronic myeloid leukemia, prefibrotic myelofibrosis and RARS-T (refractory anemia with ring sideroblasts associated with marked thrombocytosis). A JAK2 mutation is found in 50-70% of patients with ET, myelofibrosis or RARS-T and is capable of distinguishing reactive from clonal thrombocytosis.

RISK STRATIFICATION

Current risk stratification in PV and ET is designed to estimate the likelihood of thrombotic complications: high-risk is defined by the presence of age >60 years or presence of thrombosis history; low-risk is defined by the absence of both of these two risk factors. Recent data considers JAK2V617F and cardiovascular (CV) risk factors as additional risk factors for thrombosis. Presence of extreme thrombocytosis (platelet count >1,000 × 10(9) /L) might be associated with acquired von Willebrand syndrome (AvWS) and, therefore, risk of bleeding. Risk factors for shortened survival in both PV and ET include advanced age, leukocytosis, and history of thrombosis.

RISK-ADAPTED THERAPY

Survival is near-normal in ET and reasonably long in PV. The 10-year risk of leukemic/fibrotic transformation is <1%/1% in ET and <3%/10% in PV. In contrast, the risk of thrombosis exceeds 20%. The main goal of therapy is therefore to prevent thrombohemorrhagic complications. In low risk patients, this is effectively and safely accomplished by the use of low-dose aspirin in both PV and ET and phlebotomy (hematocrit target of <45%) in PV. In high risk patients, treatment with hydroxyurea is additionally recommended, although not mandated in older patients without JAK2V617F or CV risk factors. Treatment with busulfan or interferon-α is usually effective in hydroxyurea failures. Screening for clinically significant AvWS is recommended before administrating aspirin in the presence of extreme thrombocytosis.

Mutations and prognosis in primary myelofibrosis

Patient outcome in primary myelofibrosis (PMF) is significantly influenced by karyotype. We studied 879 PMF patients to determine the individual and combinatorial prognostic relevance of somatic mutations. Analysis was performed in 483 European patients and the seminal observations were validated in 396 Mayo Clinic patients. Samples from the European cohort, collected at time of diagnosis, were analyzed for mutations in ASXL1, SRSF2, EZH2, TET2, DNMT3A, CBL, IDH1, IDH2, MPL and JAK2. Of these, ASXL1, SRSF2 and EZH2 mutations inter-independently predicted shortened survival. However, only ASXL1 mutations (HR: 2.02; P<0.001) remained significant in the context of the International Prognostic Scoring System (IPSS). These observations were validated in the Mayo Clinic cohort where mutation and survival analyses were performed from time of referral. ASXL1, SRSF2 and EZH2 mutations were independently associated with poor survival, but only ASXL1 mutations held their prognostic relevance (HR: 1.4; P=0.04) independent of the Dynamic IPSS (DIPSS)-plus model, which incorporates cytogenetic risk. In the European cohort, leukemia-free survival was negatively affected by IDH1/2, SRSF2 and ASXL1 mutations and in the Mayo cohort by IDH1 and SRSF2 mutations. Mutational profiling for ASXL1, EZH2, SRSF2 and IDH identifies PMF patients who are at risk for premature death or leukemic transformation.

Assessing efficacy in myelofibrosis treatment: a focus on JAK inhibition

Myelofibrosis (MF) is characterized by splenomegaly, anemia and a debilitating symptom burden (e.g., fatigue, night sweats, pruritus, bone and muscle pain, undesired weight loss). Moreover, these symptoms impair activities of daily living and quality of life. Until recently, there have been no approved therapies for MF, and management of MF has been predominantly palliative. Dysregulated JAK-STAT signaling is associated with the pathologic MF disease state. A novel class of therapies, the JAK inhibitors, offers the potential to abrogate this pathologic signaling pathway. In clinical trials of patients with intermediate- and high-risk MF, JAK inhibitors have demonstrated efficacy in reducing splenomegaly and MF-associated symptoms. Evidence from ruxolitinib trials also suggests that JAK inhibitors may improve survival outcomes.

BCR-ABL1-negative chronic myeloid neoplasms: an update on management techniques

Recent discoveries concerning mutations associated with chronic myeloproliferative neoplasms have modified our understanding of the biology of these incurable diseases and guided us to the development of inhibitors active on the constitutively activated JAK-STAT pathway. Concurrently, numerous studies dealt with clinical issues; it led to a revised WHO classification; clarified the role of mutated JAK2 and leukocytosis in the pathogenesis of cardiovascular events; allowed the development of risk prognostic scores and tools for monitoring response to therapy; and resulted in completion of Phase III trials with JAK2 inhibitor in myelofibrosis. All these results hold the promise of improving patient prognostication and therapeutic approach, with the aim of efficiently preventing disease-associated complications and, hopefully, to improve the dismal survival associated with myelofibrosis. This review discusses how to manage, according to current clinical practice, the steps of diagnosis, prognostication and therapeutic choices in myeloproliferative neoplasm patients.

Polycythemia vera and essential thrombocythemia: 2012 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

Polycythemia vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms primarily characterized by erythrocytosis and thrombocytosis, respectively. Other disease features include leukocytosis, splenomegaly, thrombohemorrhagic complications, vasomotor disturbances, pruritus, and a small risk of disease progression into acute myeloid leukemia or myelofibrosis.

DIAGNOSIS

Almost all patients with PV harbor a JAK2 mutation. When PV is suspected, the presence of a JAK2 mutation confirms the diagnosis and its absence, combined with normal or increased serum erythropoietin level, excludes the diagnosis. Differential diagnosis of ET had to include chronic myelogenous leukemia and prefibrotic myelofibrosis. A JAK2 mutation is found in approximately 60% of patients with ET.

RISK STRATIFICATION

Current risk stratification in PV and ET is designed to estimate the likelihood of thrombotic complications: high-risk is defined by the presence of age >60 years or presence of thrombosis history; low-risk is defined by the absence of both of these two risk factors. Presence of extreme thrombocytosis (platelet count >1,000 × 10(9)/L) might be associated with acquired von Willebrand syndrome (AvWS) and, therefore, risk of bleeding. Risk factors for shortened survival in both PV and ET include advanced age, leukocytosis, and history of thrombosis.

RISK-ADAPTED THERAPY

Survival is near-normal in ET and reasonably long in PV. The 10-year risk of leukemic/fibrotic transformation is <1%/1% in ET and <3%/10% in PV. In contrast, the risk of thrombosis exceeds 20%. The main goal of therapy is therefore to prevent thrombohemorrhagic complications and this is effectively and safely accomplished by the use of low-dose aspirin (PV and ET), phlebotomy (PV) and hydroxyurea (high risk PV and ET). Treatment with busulfan or interferon-α is usually effective in hydroxyurea failures. Screening for clinically significant AvWS is recommended before administrating aspirin in the presence of extreme thrombocytosis.

Pathophysiology of acquired von Willebrand disease: a concise review

Acquired von Willebrand disease (AVWD) is a rare, underdiagnosed hemorrhagic disorder, which is similar to congenital VWD with regard to the clinical and laboratory parameters; however, it is found in individuals with no positive family history and has no genetic basis. The etiology is varied, the commonest being hematoproliferative disorders and cardiovascular disorders. Other disorders associated with AVWD are autoimmune disorders such as systematic lupus erythematosus, hypothyroidism, and neoplasia, or it may also be drug induced. In quite a few cases, the etiology is unknown. The pathogenic mechanisms are different in different underlying disorders or they may be overlapping among these disorders. Some of the proposed mechanisms include the development of autoantibodies, selective absorption of high molecular weight von Willebrand factor (VWF) multimers, non-selective absorption of VWF, mechanical destruction of VWF under high shear stress, and increased proteolysis. This report presents a concise review of the pathophysiological mechanisms of AVWD in these various underlying conditions.

Annual Clinical Updates in Hematological Malignancies: a continuing medical education series: polycythemia vera and essential thrombocythemia: 2011 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Polycythemia vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms primarily characterized by erythrocytosis and thrombocytosis, respectively. Other disease features include leukocytosis, splenomegaly, thrombohemorrhagic complications, vasomotor disturbances, pruritus, and a small risk of disease progression into acute leukemia or myelofibrosis.

DIAGNOSIS

Diagnosis is based on JAK2 mutation status (PV and ET), serum erythropoietin (Epo) level (PV), and bone marrow histopathology (ET). The presence of a JAK2 mutation and subnormal serum Epo level confirm a diagnosis of PV. Differential diagnosis in ET should include chronic myelogenous leukemia and prefibrotic myelofibrosis.

RISK STRATIFICATION

Current risk stratification in PV and ET is designed to estimate the likelihood of thrombotic complications: high-risk-age > 60 years or presence of thrombosis history; low-risk-absence of both of these two risk factors. Presence of extreme thrombocytosis (platelet count > 1,000 x 10⁹/L) might be associated with acquired von Willebrand syndrome (AvWS) and, therefore, risk of bleeding. Risk factors for shortened survival in both PV and ET include age > 60 years, leukocytosis, history of thrombosis, and anemia.

RISK-ADAPTED THERAPY

Survival is near-normal in ET and reasonably long in PV. The 10-year risk of leukemic/fibrotic transformation is < 1%/1% in ET and < 5%/10% in PV. In contrast, the risk of thrombosis exceeds 20%. The main goal of therapy is therefore to prevent thrombohemorrhagic complications and this is effectively and safely accomplished by the use of low-dose aspirin (PV and ET), phlebotomy (PV), and hydroxyurea (high risk PV and ET). Treatment with busulfan or interferon-a is usually effective in hydroxyurea failures.

Philadelphia-negative classical myeloproliferative neoplasms: critical concepts and management recommendations from European LeukemiaNet

We present a review of critical concepts and produce recommendations on the management of Philadelphia-negative classical myeloproliferative neoplasms, including monitoring, response definition, first- and second-line therapy, and therapy for special issues. Key questions were selected according the criterion of clinical relevance. Statements were produced using a Delphi process, and two consensus conferences involving a panel of 21 experts appointed by the European LeukemiaNet (ELN) were convened. Patients with polycythemia vera (PV) and essential thrombocythemia (ET) should be defined as high risk if age is greater than 60 years or there is a history of previous thrombosis. Risk stratification in primary myelofibrosis (PMF) should start with the International Prognostic Scoring System (IPSS) for newly diagnosed patients and dynamic IPSS for patients being seen during their disease course, with the addition of cytogenetics evaluation and transfusion status. High-risk patients with PV should be managed with phlebotomy, low-dose aspirin, and cytoreduction, with either hydroxyurea or interferon at any age. High-risk patients with ET should be managed with cytoreduction, using hydroxyurea at any age. Monitoring response in PV and ET should use the ELN clinicohematologic criteria. Corticosteroids, androgens, erythropoiesis-stimulating agents, and immunomodulators are recommended to treat anemia of PMF, whereas hydroxyurea is the first-line treatment of PMF-associated splenomegaly. Indications for splenectomy include symptomatic portal hypertension, drug-refractory painful splenomegaly, and frequent RBC transfusions. The risk of allogeneic stem-cell transplantation-related complications is justified in transplantation-eligible patients whose median survival time is expected to be less than 5 years.