Survival and prognosis among 1545 patients with contemporary polycythemia vera: an international study

Incidence and risk factors for myelofibrotic transformation among 272 Chinese patients with JAK2-mutated polycythemia vera

Post-polycythemia vera myelofibrosis (post-PV MF) is a critical hematologic evolution of polycythemia vera (PV). The main purpose of the present study was to identify the possible risk factors for the occurrence and prognosis of post-PV MF in Chinese patients with PV. A cohort of 272 Chinese PV patients with JAK2(V617F) or exon12 mutation was retrospectively analyzed. Of the 272 patients with PV, 63 developed post-PV MF. Platelet count >550 × 10(9) /L and splenomegaly were identified as independent risk factors for post-PV MF. The median duration of survival for post-PV MF patients was 8 years. Anemia and age >65 years at diagnosis of post-PV MF were identified as significant predictors for the poor prognosis of post-PV MF. In conclusion, platelet counts and splenomegaly were significant predictors for the transformation to post-PV MF, while anemia (hemoglobin levels <100 g/L) and age>65 years were significant predictors for poor prognosis of post-PV MF in Chinese PV patients with JAK2(V617F) or exon12 mutation.

Blast transformation and fibrotic progression in polycythemia vera and essential thrombocythemia: a literature review of incidence and risk factors

Polycythemia vera (PV) and essential thrombocythemia (ET) constitute two of the three BCR-ABL1-negative myeloproliferative neoplasms and are characterized by relatively long median survivals (approximately 14 and 20 years, respectively). Potentially fatal disease complications in PV and ET include disease transformation into myelofibrosis (MF) or acute myeloid leukemia (AML). The range of reported frequencies for post-PV MF were 4.9–6% at 10 years and 6–14% at 15 years and for post-ET MF were 0.8–4.9% at 10 years and 4–11% at 15 years. The corresponding figures for post-PV AML were 2.3–14.4% at 10 years and 5.5–18.7% at 15 years and for post-ET AML were 0.7–3% at 10 years and 2.1–5.3% at 15 years. Risk factors cited for post-PV MF include advanced age, leukocytosis, reticulin fibrosis, splenomegaly and JAK2V617F allele burden and for post-ET MF include advanced age, leukocytosis, anemia, reticulin fibrosis, absence of JAK2V617F, use of anagrelide and presence of ASXL1 mutation. Risk factors for post-PV AML include advanced age, leukocytosis, reticulin fibrosis, splenomegaly, abnormal karyotype, TP53 or RUNX1 mutations as well as use of pipobroman, radiophosphorus (P³²) and busulfan and for post-ET AML include advanced age, leukocytosis, anemia, extreme thrombocytosis, thrombosis, reticulin fibrosis, TP53 or RUNX1 mutations. It is important to note that some of the aforementioned incidence figures and risk factor determinations are probably inaccurate and at times conflicting because of the retrospective nature of studies and the inadvertent labeling, in some studies, of patients with prefibrotic primary MF or ‘masked' PV, as ET. Ultimately, transformation of MPN leads to poor outcomes and management remains challenging. Further understanding of the molecular events leading to disease transformation is being investigated.

Clinical features of Japanese polycythemia vera and essential thrombocythemia patients harboring CALR, JAK2V617F, JAK2Ex12del, and MPLW515L/K mutations

The risk of complication of polycythemia vera (PV) and essential thrombocythemia (ET) by thrombosis in Japanese patients is clearly lower than in western populations, suggesting that genetic background such as race may influence the clinical features. This study aimed to clarify the relationship between genetic mutations and haplotypes and clinical features in Japanese patients with PV and ET. Clinical features were assessed prospectively among 74 PV and 303 ET patients. There were no clinical differences, including JAK2V617F allele burden, between PV patients harboring the various genetic mutations. However, CALR mutation-positive ET patients had a significantly lower WBC count, Hb value, Ht value, and neutrophil alkaline phosphatase score (NAP), and significantly more platelets, relative to JAK2V617F-positive ET patients and ET patients with no mutations. Compared to normal controls, the frequency of the JAK246/1 haplotype was significantly higher among patients with JAK2V617F, JAK2Ex12del, or MPL mutations, whereas no significant difference was found among CALR mutation-positive patients. CALR mutation-positive patients had a lower incidence of thrombosis relative to JAK2V617F-positive patients. Our findings suggest that JAK2V617F-positive ET patients and CALR mutation-positive patients have different mechanisms of occurrence and clinical features of ET, suggesting the potential need for therapy stratification in the future.

Neutrophilic leukocytosis in advanced stage polycythemia vera: hematopathologic features and prognostic implications

Polycythemia vera in 20-30% of cases progresses towards post-polycythemic myelofibrosis, an advanced phase characterized by decreased red blood cells counts and increasing splenomegaly with extramedullary hematopoiesis. There is evidence that the presence of neutrophilic leukocytosis at polycythemia vera disease outset is associated with an increased risk of recurrent thrombosis. However, its clinical significance when developing later in the course of the disease is not well defined. Over a period of 8 years we identified from the files of two reference centers 10 patients (7M/3F, median age: 68 years) who developed persistent absolute leukocytosis ≥ 13 × 10⁹/l (median: 25.1 × 10⁹/l; range: 16.1-89.7 × 10⁹/l) at or around the time of diagnosis of post-polycythemic myelofibrosis (median interval from diagnosis:0 months; range: -6/31) and persisted for a median period of 13 months. Peripheral blood smears showed numerous neutrophils without dysplastic features and, in four, ≥ 10% immature myeloid precursors. In five cases, corresponding marrow specimens obtained at or immediately after the onset of leukocytosis showed a markedly increased myeloid:erythroid ratio due to granulocytic proliferation. No change in JAK2 and BCR-ABL1 status or cytogenetic evolution was associated with the development of leukocytosis. The mutational status of CSF3R, SETBP1, and SRSF2, genes associated with other chronic myeloid neoplasms where neutrophilic leukocytosis occurs, was investigated but all cases showed wild-type only alleles. Four patients died after developing leukocytosis and one experienced worsening disease. Compared with a control group of post-polycythemic myelofibrosis patients (n=23) who never developed persistent leukocytosis, patients with leukocytosis showed higher white blood cells counts and a shorter overall survival. This is the first study describing the development of significant neutrophilic leukocytosis during advanced stages of polycythemia vera; it includes comprehensive hematologic, marrow morphological, molecular, and clinical data. Our findings suggest that persistent leukocytosis occurring at or around the time of progression to post-polycythemic myelofibrosis is associated with an overall more aggressive course of the disease.

Glomerular diseases and cancer: evaluation of underlying malignancy

Onconephrology is an emerging medical subspecialty focused on the numerous interconnections between cancer and kidney diseases. Patient with malignancies commonly experience kidney problems including acute kidney injury, tumor lysis syndrome, fluid and electrolyte disorders and chronic kidney disease, often as a consequence of the anti-cancer treatment. Conversely, a number of glomerulopathies, tubulopathies and vascular renal diseases can early signal the presence of an underlying cancer. Furthermore, the administration of immunosuppressive drugs, especially cytotoxic drugs and calcineurin inhibitors, may strongly impair the immune response increasing the risk of cancer. The objective of this review article is to: (i) discuss paraneoplastic glomerular disease, (ii) review cancer as an adverse effect of immunosuppressive agents used to treat glomerulopathies, and (iii) in the absence of international approved guidelines, propose a screening program based on expert opinion aimed at guiding nephrologists to early detect malignancies during their clinical practice.

Chronic lymphocytic leukemia and myeloproliferative neoplasms concurrently diagnosed: clinical and biological characteristics

Chronic lymphocytic leukemia (CLL) and myeloproliferative neoplasms (MPN) may occur concomitantly. However, little is known about the pathobiological characteristics and interaction between the neoplastic clones in these rare cases of coinciding malignancies. We retrospectively examined the clinical and biological characteristics of 13 patients with concomitant CLL and MPN--eight primary myelofibrosis (PMF), three essential thrombocytosis (ET), and two polycythemia vera (PV)--who presented to our institution between 1998 and 2014, and tested all patients for MPN-specific aberrations, such as JAK2, MPL and CALR mutations. Along with epidemiological and molecular characterization of this rare condition, we found that JAK2 mutation can be detected 9 years prior to PMF diagnosis, suggesting that PMF clinical phenotype may require several years to develop and CLL/MPN clinical co-occurrence might be sustained by common molecular events. Some features of these patients suggest that pathobiologies of these diseases might be intertwined.

Proinflammatory Cytokine IL-6 and JAK-STAT Signaling Pathway in Myeloproliferative Neoplasms

The recent JAK1/2 inhibitor trial in myeloproliferative neoplasms (MPNs) showed that reducing inflammation can be more beneficial than targeting gene mutants. We evaluated the proinflammatory IL-6 cytokine and JAK-STAT signaling pathway related genes in circulating CD34⁺ cells of MPNs. Regarding laboratory data, leukocytosis has been observed in polycythemia vera (PV) and JAK2V617F mutation positive versus negative primary myelofibrosis (PMF) patients. Moreover, thrombocytosis was reduced by JAK2V617F allele burden in essential thrombocythemia (ET) and PMF. 261 significantly changed genes have been detected in PV, 82 in ET, and 94 genes in PMF. The following JAK-STAT signaling pathway related genes had augmented expression in CD34⁺ cells of MPNs: CCND3 and IL23A regardless of JAK2V617F allele burden; CSF3R, IL6ST, and STAT1/2 in ET and PV with JAK2V617F mutation; and AKT2, IFNGR2, PIM1, PTPN11, and STAT3 only in PV. STAT5A gene expression was generally reduced in MPNs. IL-6 cytokine levels were increased in plasma, as well as IL-6 protein levels in bone marrow stroma of MPNs, dependent on JAK2V617F mutation presence in ET and PMF patients. Therefore, the JAK2V617F mutant allele burden participated in inflammation biomarkers induction and related signaling pathways activation in MPNs.

Natural killer cells in patients with polycythemia vera

Natural killer cells (NK) are pivotal cells of innate immunity. They are potent antileukemic cytotoxic effectors. A defect in their cytotoxicity has been described in some hematopoietic malignancies such as acute myeloid leukemia, multiple myeloma and myelodysplastic syndromes. This defect is at least partially linked to a decreased or absent expression of some activating NK cells molecules, more particularly the so-called natural cytotoxicity receptors. In the present study, we more particularly focused our attention on NK cells of polycythemia vera, a myeloproliferative disease characterized by the presence of mutated JAK2 tyrosine kinase. The polymerase chain reaction analysis of NK cells from patients showed that they expressed the mutated form of JAK2. In polycythemia vera the proportion of NK was increased compared to healthy donors. The proliferative and cytotoxic abilities of NK cells from patients were similar to healthy donors. Expression of activating or inhibitory receptors was comparable in patients and donors, with nonetheless an imbalance for the inhibitory form of the CD158a,h couple of receptors in patients. Finally, the transcriptomic profile analysis clearly identified a discriminant signature between NK cells from patients and donors that could putatively be the consequence of abnormal continuous activation of mutated JAK2.

Acute Non-Atherosclerotic ST-Segment Elevation Myocardial Infarction in an Adolescent with Concurrent Hemoglobin H-Constant Spring Disease and Polycythemia Vera

Thrombosis is a major complication of polycythemia vera (PV) and also a well-known complication of thalassemia. We reported a case of non-atherosclerotic ST-segment elevation myocardial infarction (STEMI) in a 17-year-old man with concurrent post-splenectomized hemoglobin H-Constant Spring disease and JAK2 V617F mutation-positive PV. The patient initially presented with extreme thrombocytosis (platelet counts greater than 1,000,000/µL) and three months later developed an acute STEMI. Coronary artery angiography revealed an acute clot in the right coronary artery without atherosclerotic plaque. He was treated with plateletpheresis, hydroxyurea and antiplatelet agents. The platelet count decreased and his symptoms improved. This case represents the importance of early diagnosis, awareness of the increased risk for thrombotic complications, and early treatment of PV in patients who have underlying thalassemia with marked thrombocytosis.

Risk of second primary malignancies and survival of adult patients with polycythemia vera: A United States population-based retrospective study

Although the median survival in polycythemia vera (PV) is 14 years, mortality is higher than in an age- and sex-matched population. This study included 3941 PV patients diagnosed between 2000-2012 from Surveillance, Epidemiology and End Results (SEER) 13 registry to determine 5-year survival and the incidence of second primary malignancies (SPM). The actuarial 5 year survival in the overall cohort was 79.5%. The cumulative incidence of SPM was 13.1% at 10 years. SPMs occurred at a standardized incidence ratio (SIR) of 1.29 (95% CI = 1.16-1.43; p < 0.001) with an absolute excess risk (AER) of 42.49 per 10 000 population. A significantly higher risk was noted for acute myeloid leukemia (SIR = 12.24; 95% CI = 8.17-17.8; p-value < 0.001) and chronic myeloid leukemia (SIR = 10.66; 95% CI = 3.75-19.6; p-value < 0.001). Patients with PV are at a high risk of SPM and leukemic transformation, which may compromise long-term survival.

Essential Thrombocythemia and Polycythemia Vera: Focus on Clinical Practice

Bone marrow (BM) morphologic features remain the cornerstone of diagnosis in both essential thrombocythemia (ET) and polycythemia vera (PV). In addition, recently discovered mutations, such as JAK2, CALR, and MPL, have proven useful in facilitating the diagnostic process. A JAK2 mutation is expected in PV, and its absence makes the diagnosis unlikely. However, JAK2 mutations also occur in about 60% of patients with ET, which underlines the need for BM examination in distinguishing JAK2-mutated ET from PV when the hemoglobin/hematocrit level is diagnostically equivocal (ie, as in "masked" PV). Most patients with JAK2-unmutated ET express CALR or MPL mutations, with respective estimated incidences of 22% and 3%, while approxmately 15% are wild-type for all 3 mutations (ie, they are triple-negative). As such, CALR first, followed by MPL if CALR is absent, mutation screening is appropriate in the diagnostic work-up of JAK2-unmutated ET but does not replace the need for BM morphologic examination in (1) confirming the diagnosis in triple-negative ET and (2) distinguishing ET from other myeloproliferative neoplasms that share the same mutations, including masked PV and early/prefibrotic myelofibrosis. Young patients (aged < 60 years) with ET or PV and no history of thrombosis are conventionally regarded as having "low-risk" disease. First-line treatment in low-risk PV is phlebotomy to achieve a hematocrit target of 45% and low-dose aspirin, and first-line treatment in ET is observation alone in the absence of additional risk factors for arterial thrombosis (ie, JAK2 mutation and cardiovascular risk factors) or low-dose aspirin therapy, once or twice daily, in the presence of one or both of these risk factors, respectively. Cytoreductive therapy is indicated in high-risk (patients aged ≥ 60 years or a history of thrombosis) PV or ET in the form of hydroxyurea as first-line and interferon alfa or busulfan as second-line drugs of choice. We do not use ruxolitinib in patients with PV unless they have severe pruritus or symptomatic splenomegaly that is proved to be refractory to hydroxyurea, interferon alfa, and busulfan.

Polycythemia Vera: An Appraisal of the Biology and Management 10 Years After the Discovery of JAK2 V617F

Polycythemia vera (PV) is a chronic myeloproliferative neoplasm that is associated with a substantial symptom burden, thrombohemorrhagic complications, and impaired survival. A decade after the seminal discovery of an activating mutation in the tyrosine kinase JAK2 in nearly all patients with PV, new treatment options are finally beginning to emerge, necessitating a critical reappraisal of the underlying pathogenesis and therapeutic modalities available for PV. Herein, we comprehensively review clinical aspects of PV including diagnostic considerations, natural history, and risk factors for thrombosis. We summarize recent studies delineating the genetic basis of PV, including their implications for evolution to myelofibrosis and secondary acute myeloid leukemia. We assess the quality of evidence to support the use of currently available therapies, including aspirin, phlebotomy, hydroxyurea, and interferon. We analyze recent studies evaluating the safety and efficacy of JAK inhibitors, such as ruxolitinib, and evaluate their role in the context of other available therapies for PV. This review provides a framework for practicing hematologists and oncologists to make rational treatment decisions for patients with PV.

Is there a role for JAK inhibitors in BCR-ABL1-negative myeloproliferative neoplasms other than myelofibrosis?

Current data suggest that constitutively active JAK-STAT signaling plays a central role in the pathogenesis of BCR-ABL1-negative myeloproliferative neoplasms (MPNs), regardless of the specific underlying molecular abnormality. This observation provides strong rationale for use of JAK inhibitors for MPN treatment, and these drugs were first tested in myelofibrosis (MF) patients. Ruxolitinib, a JAK-1/2 inhibitor, is effective at controlling splenomegaly and constitutional symptoms, but has limited benefit in reversing bone marrow fibrosis or inducing complete or partial remissions. Ruxolitinib is currently in Phase 3 testing for treatment of hydroxyurea resistant/intolerant polycythemia vera (PV). Preliminary data reveals response rates of 60% for hematocrit control and 38% for spleen volume reduction per protocol-defined criteria, in addition to improving disease-related symptoms. These endpoints however have limited value as surrogates for long-term clinically relevant outcomes such as freedom-from-cardiovascular/thrombohemorrhagic events or time-to-hematological transformation, and the early crossover design of the aforementioned trial introduces limitations in terms of analysis of these latter endpoints. In contrast, other recent trials in PV have demonstrated the feasibility of using long-term clinically relevant outcomes as a primary endpoint. We also discuss the role of JAK inhibitors for treatment of CSF3RT618I-mutated chronic neutrophilic leukemia and hematologic malignancies with rearranged JAK2 gene.

Rationale for revision and proposed changes of the WHO diagnostic criteria for polycythemia vera, essential thrombocythemia and primary myelofibrosis

The 2001/2008 World Health Organization (WHO)-based diagnostic criteria for polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF) were recently revised to accomodate new information on disease-specific mutations and underscore distinguishing morphologic features. In this context, it seems to be reasonable to compare first major diagnostic criteria of the former WHO classifications for myeloproliferative neoplasm (MPN) and then to focus on details that have been discussed and will be proposed for the upcoming revision of diagnostic guidelines. In PV, a characteristic bone marrow (BM) morphology was added as one of three major diagnostic criteria, which allowed lowering of the hemoglobin/hematocrit threshold for diagnosis, which is another major criterion, to 16.5 g/dl/49% in men and 16 g/dl/48% in women. The presence of a JAK2 mutation remains the third major diagnostic criterion in PV. Subnormal serum erythropoietin level is now the only minor criterion in PV and is used to capture JAK2-unmutated cases. In ET and PMF, mutations that are considered to confirm clonality and specific diagnosis now include CALR, in addition to JAK2 and MPL. Also in the 2015 discussed revision, overtly fibrotic PMF is clearly distinguished from early/prefibrotic PMF and each PMF variant now includes a separate list of diagnostic criteria. The main rationale for these changes was to enhance the distinction between so-called masked PV and JAK2-mutated ET and between ET and prefibrotic early PMF. The proposed changes also underscore the complementary role, as well as limitations of mutation analysis in morphologic diagnosis. On the other hand, discovery of new biological markers may probably be expected in the future to enhance discrimination of the different MPN subtypes in accordance with the histological BM patterns and corresponding clinical features.

Evolving Therapeutic Options for Polycythemia Vera: Perspectives of the Canadian Myeloproliferative Neoplasms Group

Polycythemia vera (PV) is a clonal stem cell disorder characterized by erythrocytosis and associated with burdensome symptoms, reduced quality of life, risk of thrombohemorrhagic complications, and risk of transformation to myelofibrosis and acute myeloid leukemia. The discovery of the JAK2 V617 mutation marked a significant milestone in understanding the pathophysiology of the disease and subsequently the diagnostic and therapeutic approaches. The current diagnostic criteria for PV are based on hemoglobin level and presence of the JAK2 V617 mutation. The treatment is geared toward prevention of thrombotic events, normalization of blood counts, control of disease-related symptoms, and potential prolongation of survival. Cytoreductive therapy is indicated in patients at increased risk of thrombosis. Hydroxyurea (HU) remains the most commonly used first-line cytoreductive therapy and is superior to phlebotomy in reducing risk of arterial and venous thrombosis. Interferon (IFN) is used either at failure of HU or in selected patients as first-line therapy. The results of pegylated IFN in phase 2 studies appear encouraging, with molecular responses occurring in some patients. Ongoing phase 3 studies of HU versus pegylated IFN will define the optimal first-line cytoreductive therapy for PV. A recent phase 3 trial has shown the superiority of the JAK1/2 inhibitor ruxolitinib in comparison to best available treatment in HU-intolerant or -resistant patients. The therapeutic landscape of PV is likely to change in the near future. In this report, we assess the potential impact of the changing landscape of PV management on daily practice.

Ruxolitinib for the treatment of patients with polycythemia vera

Polycythemia vera (PV) is a hematopoietic proliferative disorder associated with Janus-associated kinase/signal transducer and activator of transcription pathway dysregulation resulting in erythrocytosis and, possibly, leukocytosis and thrombocytosis. Patients diagnosed with PV experience a broad range of symptoms associated with a reduced quality of life, often develop splenomegaly, and have an increased risk of death compared with age-matched subjects without PV. Current treatment options, notably hydroxyurea, help with disease management; however, insufficient efficacy or progressive resistance occurs in some patients, highlighting the need for new treatment options. Ruxolitinib is an oral JAK1/JAK2 inhibitor that has been evaluated in Phase II and III clinical trials in patients with PV, who are intolerant of or resistant to hydroxyurea. In this setting, ruxolitinib treatment has demonstrated normalization of blood cell counts, reduction in splenomegaly and improvements in PV-related symptom burden.

How We Treat Myeloproliferative Neoplasms

The present report focuses on management strategies for the myeloproliferative neoplasm according to the structure and processes we use within our center, a large tertiary unit in central London. The standard procedures for achieving an accurate diagnosis and risk stratification and therapeutic strategies for these diseases with a detailed focus on contentious areas are discussed. In the 9 years after the description of the Janus kinase 2 mutation, this field has altered quite radically in several aspects. For example, a new therapeutic paradigm exists, especially for myelofibrosis. We share how our unit has adapted to these changes.

The clinical and laboratory evaluation of the patient with erythrocytosis

Erythrocytosis is frequently encountered as an incidental abnormality on laboratory testing that reveals persistent elevation of the hematocrit level (>52% in men and >48% in women). In many cases, erythrocytosis is the manifestation of an underlying cardiopulmonary process, drug-induced due to androgens, or secondary to smoking, rather than a primary bone marrow disorder such as polycythemia vera. A systematic approach to the clinical and laboratory evaluation of each patient is indicated to consider diverse differential diagnosis possibilities and to identify the underlying etiology of erythrocytosis in order to formulate appropriate subspecialist referral and management plans. A thorough medical history and meticulous physical examination supplemented by a focused initial laboratory evaluation will enable the general practitioner to ascertain the etiology of erythrocytosis in the majority of cases. Patients with clinical and laboratory features suggestive of polycythemia vera and those patients without an apparent underlying condition known to cause erythrocytosis benefit from early referral to a hematologist for further specialized diagnostic evaluation and therapy considerations.

Current and future treatment options for polycythemia vera

Patients with polycythemia vera (PV), a myeloproliferative neoplasm characterized by an elevated red blood cell mass, are at high risk of vascular and thrombotic complications and have reduced quality of life due to a substantial symptom burden that includes pruritus, fatigue, constitutional symptoms, microvascular disturbances, and bleeding. Conventional therapeutic options aim at reducing vascular and thrombotic risk, with low-dose aspirin and phlebotomy as first-line recommendations for patients at low risk of thrombotic events and cytoreductive therapy (usually hydroxyurea or interferon alpha) recommended for high-risk patients. However, long-term effective and well-tolerated treatments are still lacking. The discovery of mutations in Janus kinase 2 (JAK2) as the underlying molecular basis of PV has led to the development of several targeted therapies, including JAK inhibitors, and results from the first phase 3 clinical trial with a JAK inhibitor in PV are now available. Here, we review the current treatment landscape in PV, as well as therapies currently in development.

Interferon in polycythemia vera and related neoplasms. Can it become the treatment of choice without a randomized trial?

Recently, it was concluded that the optimal therapy for essential thrombocythemia and polycythemia vera, either recombinant interferon alpha (rIFNα) or hydroxyurea can only be determined by the completion of a randomized clinical trial. We present our recommendations for the use of rIFNα for those patients who are not candidates for the randomized trial. We argue for rethinking the approach whether we should continue to wait for the results from a randomized trial before recommending treatment with rIFNα for those unable and unwilling to enter these trials. The interferon story shows that clinical experience may be an alternative path to follow when making treatment decisions and recommendations in orphan diseases.

Impact of bone marrow pathology on the clinical management of Philadelphia chromosome-negative myeloproliferative neoplasms

Philadelphia chromosome-negative myeloproliferative neoplasms include primary myelofibrosis (PMF), polycythemia vera (PV), and essential thrombocythemia (ET). Although these 3 entities share many pathogenic characteristics, such as dysregulated Janus kinase (JAK)/signal transducer and activator of transcription signaling, they differ substantially regarding prognosis, progression to myelofibrosis (MF), risk of leukemic transformation, and specific medical needs. Accurate diagnosis and classification of myeloproliferative neoplasms are prerequisites for appropriate risk-based therapy and should be based on an integrated approach following the World Health Organization guidelines that, in addition to clinical, molecular, and cytogenetic evaluation, includes the examination of bone marrow morphology. Reticulin fibrosis at presentation in ET and PV is associated with increased risk of myelofibrotic transformation, and higher fibrosis grade in patients with MF is associated with worse prognosis. Additional assessment of collagen deposition and osteosclerosis may further increase diagnostic and prognostic precision. Moreover, the evaluation of bone marrow pathology has become very important in the new era of disease-modifying agents. In randomized controlled phase 3 studies, the JAK1/JAK2 inhibitor ruxolitinib provided rapid and lasting improvement in MF-related splenomegaly and symptom burden as well as a survival advantage compared with placebo or best available therapy. Follow-up for up to 5 years of patients who participated in a phase 1/2 study of ruxolitinib, revealed stabilization or reversal of bone marrow fibrosis in a proportion of patients with MF. Combinations of JAK inhibitors with other therapies, including agents with antifibrotic and/or anti-inflammatory properties, may possibly decrease bone marrow fibrosis further and favorably influence clinical outcomes.

Patterns of presentation and thrombosis outcome in patients with polycythemia vera strictly defined by WHO-criteria and stratified by calendar period of diagnosis

Most studies in polycythemia vera (PV) include patients with both remote and most recent diagnostic periods and are therefore vulnerable to inaccurate interpretation of time-dependent data. We addressed the particular issue by analyzing presenting characteristics and outcome data among 1,545 patients with WHO-defined PV stratified by a diagnosis period of before or after 2005, which coincides with the first description of JAK2V617F as the molecular marker of PV. Patients diagnosed after 2005 displayed lower hemoglobin values (P < 0.0001) and older age (P = 0.007) at diagnosis; we suggest ease of diagnosis offered by a molecular marker enabled earlier diagnosis and broader application across older age groups that is further enhanced by recent trends in increased attention and health monitoring for the elderly. Post-2005 diagnosed patients were also more or less likely to receive aspirin and cytoreductive therapy, respectively, and, despite their older age distribution, displayed significantly lower risk of thrombosis in high risk disease. Regardless of the contributing factors to the latter phenomenon, our observations underscore the need to reassess current demographics and frequencies of thrombosis in clinical trial designs including thrombosis prevention in PV.

Anagrelide hydrochloride and ruxolitinib for treatment of polycythemia vera

INTRODUCTION

New treatment options for polycythemia vera (PV) have recently become available. This article reviews current treatment strategies for PV with a focus on anagrelide and ruxolitinib.

AREAS COVERED

The current treatment of PV is directed towards reducing the risk of additional thrombotic events. In addition to phlebotomy and aspirin, patients who are believed to have high-risk disease also receive cytoreductive therapy. Hydroxyurea (HU) and PEG-IFN are most commonly used first-line treatments. The use of anagrelide in PV is limited to situations where patient develops thrombohemorrhagic episodes in the setting of extreme thrombocytosis. The role of ruxolitinib in treatment of PV has not been fully established but based on a recently completed Phase III trial it will likely serve as a second-line option for patients with systemic symptoms.

EXPERT OPINION

HU and PEG-IFN are frontline therapies for patients with high-risk PV. Anagrelide use should be restricted to patients with clinical consequences of extreme thrombocytosis. Ruxolitinib is a treatment option for patients who fail frontline therapies. However, long-term effects and toxicities are not yet fully known.

Reducing symptom burden in patients with myeloproliferative neoplasms in the era of Janus kinase inhibitors

Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs) are clonal stem cell-derived malignancies that include primary myelofibrosis, polycythemia vera and essential thrombocythemia and are characterized by dysregulated Janus kinase-signal transducers and activators of transcription (JAK-STAT) signaling. Clinical manifestations include splenomegaly, cytopenias and/or systemic inflammation. Patients have a heterogeneous symptom profile that includes fatigue, loss of appetite, pruritus and night sweats, which significantly impact quality of life (QoL) and lead to poor survival outcomes. With the introduction of JAK inhibitors, improvement in disease-related symptoms has emerged as a realistic expectation of therapy and an integral measure of clinical efficacy. The JAK1/JAK2 inhibitor ruxolitinib is approved for the treatment of myelofibrosis and is currently under clinical development for polycythemia vera. Ruxolitinib has demonstrated significant reductions in symptom burden, with consequent improvements in QoL measures. With the potential to improve QoL, recognition of the impact and burden of symptoms on patients with MPNs is critical.

Oral anticoagulation to prevent thrombosis recurrence in polycythemia vera and essential thrombocythemia

It is unclear whether anticoagulation guidelines intended for the general population are applicable to patients with polycythemia vera (PV) and essential thrombocythemia (ET). In the present study, the risk of thrombotic recurrence was analyzed in 150 patients with PV and ET treated with vitamin K antagonists (VKA) because of an arterial or venous thrombosis. After an observation period of 963 patient-years, the incidence of re-thrombosis was 4.5 and 12 per 100 patient-years under VKA therapy and after stopping it, respectively (P < 0.0005). After a multivariate adjustment for other prognostic factors, VKA treatment was associated with a 2.8-fold reduction in the risk of thrombotic recurrence. Notably, VKA therapy offset the increased risk of re-thrombosis associated with a prior history of remote thrombosis. Both the protective effect of VKA therapy and the predisposing factors for recurrence were independent of the anatomical site involved in the index thrombosis. Treatment periods with VKA did not result in a higher incidence of major bleeding as compared with those without VKA. These findings support the use of long-term anticoagulation for the secondary prevention of thrombosis in patients with PV and ET, particularly in those with history of remote thrombosis.

Therapy for myeloproliferative neoplasms: when, which agent, and how?

Myeloproliferative neoplasms, including polycythemia vera (PV), essential thrombocythemia, and myelofibrosis (MF) (both primary and secondary), are recognized for their burdensome symptom profiles, life-threatening complications, and risk of progression to acute leukemia. Recent advancements in our ability to diagnose and prognosticate these clonal malignancies have paralleled the development of MPN-targeted therapies that have had a significant impact on disease burden and quality of life. Ruxolitinib has shown success in alleviating the symptomatic burden, reducing splenomegaly and improving quality of life in patients with MF. The role and clinical expectations of JAK2 inhibition continues to expand to a variety of investigational arenas. Clinical trials for patients with MF focus on new JAK inhibitors with potentially less myelosuppression( pacritinib) or even activity for anemia (momelotinib). Further efforts focus on combination trials (including a JAK inhibitor base) or targeting new pathways (ie, telomerase). Similarly, therapy for PV continues to evolve with phase 3 trials investigating optimal frontline therapy (hydroxyurea or IFN) and second-line therapy for hydroxyurea-refractory or intolerant PV with JAK inhibitors. In this chapter, we review the evolving data and role of JAK inhibition (alone or in combination) in the management of patients with MPNs.

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.

Novel and emerging therapies for the treatment of polycythemia vera

Polycythemia vera (PV) is a chronic myeloproliferative neoplasm defined by erythrocytosis and often accompanied by leukocytosis and thrombocytosis. Current treatment options, including IFN-α and hydroxyurea, effectively manage PV in many patients. However, some high-risk patients, particularly those who become hydroxyurea-intolerant/resistant, may benefit from IFN-α or new treatment options. A better understanding of PV pathophysiology, including the role of the JAK/STAT pathway, has inspired the development of new therapies. Several JAK inhibitors directly target JAK/STAT pathway activation and have been evaluated in Phase II/III trials with promising results. Pegylated variants of IFN-α, which reduce dosing frequency and toxicity associated with recombinant IFN-α, have yielded favorable efficacy results in Phase II trials. Finally, histone deacetylase inhibitors have been developed to manage PV at the level of chromatin-regulated gene expression. The earliest Phase III results from these next-generation therapies are expected in 2014.

Ruxolitinib versus standard therapy for the treatment of polycythemia vera

BACKGROUND

Ruxolitinib, a Janus kinase (JAK) 1 and 2 inhibitor, was shown to have a clinical benefit in patients with polycythemia vera in a phase 2 study. We conducted a phase 3 open-label study to evaluate the efficacy and safety of ruxolitinib versus standard therapy in patients with polycythemia vera who had an inadequate response to or had unacceptable side effects from hydroxyurea.

METHODS

We randomly assigned phlebotomy-dependent patients with splenomegaly, in a 1:1 ratio, to receive ruxolitinib (110 patients) or standard therapy (112 patients). The primary end point was both hematocrit control through week 32 and at least a 35% reduction in spleen volume at week 32, as assessed by means of imaging.

RESULTS

The primary end point was achieved in 21% of the patients in the ruxolitinib group versus 1% of those in the standard-therapy group (P<0.001). Hematocrit control was achieved in 60% of patients receiving ruxolitinib and 20% of those receiving standard therapy; 38% and 1% of patients in the two groups, respectively, had at least a 35% reduction in spleen volume. A complete hematologic remission was achieved in 24% of patients in the ruxolitinib group and 9% of those in the standard-therapy group (P=0.003); 49% versus 5% had at least a 50% reduction in the total symptom score at week 32. In the ruxolitinib group, grade 3 or 4 anemia occurred in 2% of patients, and grade 3 or 4 thrombocytopenia occurred in 5%; the corresponding percentages in the standard-therapy group were 0% and 4%. Herpes zoster infection was reported in 6% of patients in the ruxolitinib group and 0% of those in the standard-therapy group (grade 1 or 2 in all cases). Thromboembolic events occurred in one patient receiving ruxolitinib and in six patients receiving standard therapy.

CONCLUSIONS

In patients who had an inadequate response to or had unacceptable side effects from hydroxyurea, ruxolitinib was superior to standard therapy in controlling the hematocrit, reducing the spleen volume, and improving symptoms associated with polycythemia vera. (Funded by Incyte and others; RESPONSE ClinicalTrials.gov number, NCT01243944.).

Current therapies and their indications for the Philadelphia-negative myeloproliferative neoplasms

The groundbreaking discovery of the Janus-associated kinase 2 (JAK2) V617F mutation 10 years ago resulted in an unprecedented intensive basic and clinical research in Philadelphia-negative myeloproliferative neoplasms (MPNs). During these years, many new potential targets for therapy were identified that opened the era of targeted therapy for these diseases. However, only one new drug (ruxolitinib) has been approved during the past 40 years, and, although promising new therapies are evaluated, the armamentarium to treat MPN still relies on conventional drugs, like cytotoxic agents and anagrelide. The exact role of interferon (IFN) alfa still needs to be clarified in randomized studies, although it has been shown to be effective in MPNs for more than 25 years. The current therapeutic strategy for MPNs is based on the risk of vascular complication, which is the main cause of mortality and mortality in the medium term. However, the long-term outcome may be different, with an increasing risk of transformation to myelodysplastic syndrome or acute leukemia during follow-up times. Medicines able to change this natural history have not been clearly identified yet, and allogeneic stem cell transplantation currently remains the unique curative approach, which is only justified for patients with high-risk myelofibrosis or for patients with MPNs that have transformed to myelodysplasia or acute leukemia.

Polycythemia Vera Diagnosed after Esophageal Variceal Rupture

Polycythemia vera (PV) is a chronic myeloproliferative neoplasm that leads to hyperviscosity and the risk of thrombosis. We encountered the case of a young male Filipino patient diagnosed with PV after the rupture of esophageal varices. The complete blood cell count showed a slight increase in white blood cells. An abdominal computed tomography scan disclosed splenomegaly and occlusion of the portal vein and collateral vessels. A blood examination demonstrated an increase in all three blood cell lines within three months. Based on the presence of severe hypercellularity of the bone marrow and positivity for the JAK2V617F mutation, we finally diagnosed the patient with PV.

Mechanisms of thrombogenesis in polycythemia vera

Thrombotic and cardiovascular events are among the leading causes of death for patients with polycythemia vera (PV), and thrombosis history is a key criterion for patient risk stratification and treatment strategy. Little is known, however, about mechanisms of thrombogenesis in patients with PV. This report provides an overview of thrombogenesis pathophysiology in patients with PV and elucidates the roles of conventional and nonconventional thrombotic risk factors. In addition to several conventional risk factors for thrombosis, clinical data have implicated increased hematocrit and red blood cell adhesiveness, activated platelets, leukocytosis, and elevated JAK2(V617F) allele burden in patients with PV. Furthermore, PV-related inflammation may exacerbate thrombogenesis through varied mechanisms, including endothelial damage, inhibition of natural anticoagulant pathways, and secretion of procoagulant factors. These findings suggest a direct link between myeloproliferation and thrombogenesis in PV, which is likely to provide new opportunities for targeted antithrombotic interventions aimed at decreasing PV-related morbidity and mortality.

Management of MPN beyond JAK2

Thrombocytosis has a large number of potential underlying causes, but the dominant group of hematological conditions for consideration in this setting are the myeloproliferative neoplasms (MPNs). In this chapter, we consider several key linked questions relating to the management of thrombocytosis in MPNs and discuss several issues. First, we discuss the differential diagnosis of thrombocytosis, which myeloid disorders to consider, and practical approaches to the discrimination of each individual MPN from other causes. Second, there have been several major advances in our understanding of the molecular biology of these conditions and we discuss how these findings are likely to be practically applied in the future. Third, we consider whether there is evidence that thrombocytosis contributes to the complications known to be associated with MPN: thrombosis, hemorrhage and transformation to leukemia and myelofibrosis. Last, we review current ideas for risk stratification and management of essential thrombocythemia and polycythemia vera as the 2 entities within the MPN family that are most frequently associated with thrombocytosis.

Therapy for myeloproliferative neoplasms: when, which agent, and how?

Myeloproliferative neoplasms, including polycythemia vera (PV), essential thrombocythemia, and myelofibrosis (MF) (both primary and secondary), are recognized for their burdensome symptom profiles, life-threatening complications, and risk of progression to acute leukemia. Recent advancements in our ability to diagnose and prognosticate these clonal malignancies have paralleled the development of MPN-targeted therapies that have had a significant impact on disease burden and quality of life. Ruxolitinib has shown success in alleviating the symptomatic burden, reducing splenomegaly and improving quality of life in patients with MF. The role and clinical expectations of JAK2 inhibition continues to expand to a variety of investigational arenas. Clinical trials for patients with MF focus on new JAK inhibitors with potentially less myelosuppression (pacritinib) or even activity for anemia (momelotinib). Further efforts focus on combination trials (including a JAK inhibitor base) or targeting new pathways (ie, telomerase). Similarly, therapy for PV continues to evolve with phase 3 trials investigating optimal frontline therapy (hydroxyurea or IFN) and second-line therapy for hydroxyurea-refractory or intolerant PV with JAK inhibitors. In this chapter, we review the evolving data and role of JAK inhibition (alone or in combination) in the management of patients with MPNs.

Cerebral vein thrombosis in patients with Philadelphia-negative myeloproliferative neoplasms. An European Leukemia Net study

To investigate the characteristics and clinical course of cerebral vein thrombosis (CVT) in patients with myeloproliferative neoplasms (MPN) we compared 48 patients with MPN and CVT (group MPN-CVT) to 87 with MPN and other venous thrombosis (group MPN-VT) and 178 with MPN and no thrombosis (group MPN-NoT) matched by sex, age at diagnosis of MPN (±5 years) and type of MPN. The study population was identified among 5,500 patients with MPN, from January 1982 to June 2013. Thrombophilia abnormalities were significantly more prevalent in the MPN-CVT and MPN-VT than in MPN-NoT group (P = 0.015), as well as the JAK2 V617F mutation in patients with essential thrombocythemia (P = 0.059). Compared to MPN-VT, MPN-CVT patients had a higher rate of recurrent thrombosis (42% vs. 25%, P = 0.049) despite a shorter median follow-up period (6.1 vs. 10.3 years, P = 0.019), a higher long-term antithrombotic (94% vs. 84%, P = 0.099) and a similar cytoreductive treatment (79% vs. 70%, P = 0.311). The incidence of recurrent thrombosis was double in MPN-CVT than in MPN-VT group (8.8% and 4.2% patient-years, P = 0.022), and CVT and unprovoked event were the only predictive variables in a multivariate model including also sex, blood count, thrombophilia, cytoreductive, and antithrombotic treatment (HR 1.97, 95%CI 1.05-3.72 and 2.09, 1.09-4.00, respectively).

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.