Polycythemia Vera Study Group Research Articles

Development and Validation of a Multiple Factor-Based Prognostic Score System of Thrombosis in Polycythemia Vera (MFPS-PV)

Introduction: Thrombosis is an important cause of death in patients with polycythemia vera (PV). The conventional two-tiered risk stratification is based on the Polycythemia Vera Study Group (PVSG) criteria and considered only age≥60 years and previous thrombosis as thrombotic risk factors. In the current study, we integrated genetic and clinical information into thrombosis risk stratification and aimed to improve the prediction power of thrombosis in the 2016 WHO-defined PV and propose risk-adapted treatment strategies according to the new model. Methods: Patients were eligible for inclusion if 18 years or older with a confirmed diagnosis of PV according to the 2016 WHO criteria. Clinical and laboratory data were obtained from institutional databases and direct contact with patients. Bone marrow mononuclear cells were collected from the included patients and sent for next-generation sequencing (NGS). A multivariate Cox proportional hazard regression analysis was conducted to identify independent risk factors for thrombosis-free survival (TFS). Hazard ratio (HR)-based risk score allocation was employed to obtain a multifactorial prediction model. Results: The study involved 372 patients in the training cohort and another 195 patients in the external validation cohort. The median follow-up of the training cohort was 43 months (range 3-454) (Table 1). The median age at diagnosis was 53 years (range 18-86) and 59.4% were male. Altogether, 136 patients (36.6%) suffered from thrombosis, including 52 patients (14.0%) with thrombosis before diagnosis, 68 patients (18.3%) at diagnosis, and 68 patients (18.3%) after diagnosis. Mutations in genes encoding for epigenetic modifiers were more frequent in patients with thrombosis than in patients without thrombosis after diagnosis (45.6% vs. 20.1%, p<0.001). Specifically, significant differences were noted in the frequencies of ASXL1 (16.2% vs. 5.9%, p=0.004), DNMT3A (25.0% vs. 4.6%, p<0.001) and BCOR/ BCORL1 (13.2% vs. 4.6%, p=0.017) mutations between patients with and without thrombosis after diagnosis. Multivariate analysis indicated that age≥60 years (HR 2.493, p=0.001), cardiovascular risk factors (HR 4.041, p<0.001), at least one high-risk mutation for thrombosis (mutations in DNMT3A, ASXL1, and BCOR/BCORL1) (HR 4.049, p<0.001) and previous thrombosis (HR 5.576, p<0.001) were independent risk factors for thrombosis. After assigning HR-weighted scores to each risk factor mentioned above (1, 1.5, 1.5 and 2 points respectively), a multiple factor-based prognostic score system of thrombosis was developed, classifying patients into low-risk (≤1 point), intermediate-risk (1.5-2.5 points), and high-risk (≥3 points) groups. Patients in the three groups had significantly different TFS (p<0.001) and remained consistent during external validation (Figure 1). Finally, a risk-adapted therapeutic strategy was established based on the MFPS-PV. TP and low-dose antiplatelet therapy are recommended for all patients to achieve a targeted HCT level lower than 45%. Low-risk patients are not mandatory for cytoreduction and only require low-dose antiplatelet therapy. Intermediate-risk patients are advised for antiplatelet therapy, with cytoreduction added if they have two thrombotic risk factors, previous thrombosis, or age≥60 years. High-risk patients are recommended antiplatelet and cytoreductive combination therapy. Conclusion: The MFPS-PV, integrating genetic and clinical characteristics for the first time, can significantly predict thrombosis and has great therapeutic implications. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Practice Patterns in the Diagnosis and Treatment of Polycythemia Vera in the Post-JAK2 V617F Discovery Era.

Polycythemia vera (PV) is an acquired clonal hematopoietic stem cell disorder characterized by an overproduction of red blood cells, white blood cells, and platelets; thrombotic and hemorrhagic complications; and an increased risk of transformation to myelofibrosis and acute leukemia. In 1967, the Polycythemia Vera Study Group proposed the optimal approach to diagnosis and treatment of PV, and in 2002, investigators from Johns Hopkins University School of Medicine surveyed the practice patterns of hematologists as they pertained to PV. Since this survey, the JAK2 V617F mutation was discovered, leading to a new era of discovery in the disease pathogenesis, diagnosis, and classification and treatment of PV. Our objective was to survey hematologists in the diagnosis and treatment of PV in the modern, post-JAK2 V617F discovery era. An anonymous 17-question survey was emailed to members of the Myeloproliferative Neoplasm (MPN) Research Foundation database and Aplastic Anemia and MDS International Foundation. A total of 71 surveys were used in the analysis. Diagnostic testing varied according to the respondent's clinical experience and practice type. In addition, there were marked differences in target hematocrit and platelet count among those surveyed. There continue to be variations in diagnosis and treatment of PV despite WHO guidelines and the JAK2 discovery. US-based guidelines for MPNs are needed to create consistency in the management of PV and other MPNs.

The 2006 → 2008 European Clinical, Molecular and Patholobiogical (2008 ECMP) Classification and the 2007 WHO Revised Criteria for Myeloproliferative Neoplasms

The classifications of Myeloproliferative Disorders (MPD) by the Polycythemia Vera Study Group (PVSG) and World Health Organization (WHO) used crude criteria for the diagnoses of Essential Thrombocythemia (ET), Polycythemia Vera (PV) and Primary Myelo Fibrosis (PMF). The PVSG and the 2007 WHO criteria for the diagnosis of ET and PVoverlook the very early prefibrotic stages of MPN. The 2008 European Clinical, Molecular and Pathological (2008 ECMP) criteria are sensitive for the detection of early stages of JAK2 V617F trilinear Myelo Proliferative Neoplasms (MPN) and could delineate three stages JAK2 V617F mutated ET: normocellular ET; ET with features of early PV (prodromal PV); and ET with Hypercellular Megakaryocytic Granulocytic Myeloproliferation (EMGM). The 2008 ECMP classification distinguishes six clinical PV stages that have important prognostic and therapeutic implications. Spontaneous EEC, low serum erythropoietin (EPO) levels and JAK2 mutations are highly specific for ET with PV features (prodromal PV), masked PV and classical PV. JAK2 wild type ET and MF have no blood and bone marrow features of PV. The detection and quantitation of JAK2 V617F mutation allele burden play a key-role in the diagnostic work-up and staging of ET, PV and MF patients. The JAK2 V617F mutation allele burden in heterozygous mutated ET and in combined heterozygous-homozygous or homozygous mutated PV and EMGM is of major clinical and prognostic significance. Pre-treatment bone marrow histopathology is of huge importance to document and stage the broad spectrum JAK2 mutated and JAK wild type MPN. JAK2 wild type ET carrying the MPL 515 mutation is a separate and distinct MPN entity of ET and MF without features of PV at diagnosis and during follow-up. JAK2 wild type hypercellular ET associated with Primary Megakaryocytic Granulocytic Myeloproliferation (PMGM) is the third MPN entity of elusive etiology. Myelofibrosis (MF) is not a primary MPN disease entity because Reticulin Fibrosis (RF) and Reticulin/Collagen Fibrosis (RCF) are a secondary response of polyclonal fibroblasts to cytokines released from the clonal granulocytic and megakaryocytic proliferative cells.

Three Phenotypes of JAKV617F Mutated Essential Thrombocythemia and Early Thrombocythemic Stage of Polycythemia Vera in 10 Patients: Important to Differentiate because Natural History Differ

In 10 JAK2V617F positive patients with early myeloproliferative essential thrombocythemia (ET) or polycythemia vera (PV) we sequentially used the Polycythemia Vera Study Group (PVSG), the Thrombocythemia Vera Study Group (TVSG) and the 2008 WHO criteria for the clinical diagnosis of essential thrombocythemia (ET) ad polycythemia vera (PV). Subsequently, we evaluated bone marrow features and laboratory and molecular markers including endogenous erythroid colony (EEC), serum erythropoietine (EPO) mutation for the classification of early MPD. Six symptomatic patients had a delayed diagnosis of slow onset latent (masked) ET and 4 patients presented with rapid onset PV associated with thrombocythemia. We could clearly distinguish three phenotypes of ET when the 2008 European clinical, molecular and pathological (2008 WHO-ECMP) criteria for ET and PV are applied. These include ET phenotype 1, ET phenotype type 2 with features of early polycythemia vera (PV) and normal red cell mass, and ET phenotype 3 associated with megakaryocytic granulocytic myeloproliferation (ET-MGM) in the absence of characteristic features of primary myelofibrosis (PMF). Through the presentation of a number of highly illustrative clinical cases during long-term follow-up we could demonstrate that diagnostic differentiation of three phenotypes of ET is important, because natural history clearly differ.

In Contemporary Patients with Polycythemia Vera, Rates of Thrombosis and Risk Factors Delineate a New Clinical Epidemiology

BackgroundCurrent risk stratification in Polycythemia Vera (PV), is designed to estimate the likelihood of thrombotic complications. In ECLAP large prospective study of 1638 PV cases diagnosed by Polycythemia Vera Study Group (PVSG) criteria, risk factors were age over 65 years and prior thrombotic events. After the JAK2V617F discovery, diagnosis has undergone substantial revision by the World Health Organization (WHO). Consequently, current risk factors determination should be described in patients diagnosed by the most recent recommendations and requires a large sample size with reliable and sufficiently long clinical course documentation. Accordingly, the current study includes 1545 patients with strictly WHO-defined PV diagnosed and followed-up in seven centers from Italy, Austria and the United States, belonging to the International Working Group for Myeloproliferative Neoplasm (MPN) Research and Treatment (IWG-MRT).Objective and design1) Describe the rate of thrombosis in this population;2) Report the sites and frequency of recurrences after a first arterial or venous event;3) Identify separately risk factors for arterial versus venous thrombosis and develop practically useful prognostic models.Results1. Presenting featuresThe characteristics of the cohort recruited reflected well the heterogeneity of epidemiologic and clinical features that are found in the routine clinical practice of PV. Arterial and venous thrombosis history before or at diagnosis was documented in 246 (16%) and 114 (7.4%) patients, respectively. The frequencies of arterial and venous thrombosis were lower than those recorded in the ECLAP4 (27% and 11% respectively) but comparable to those reported in the recent Cyto-PV2 (arterial 17%, venous 12%) studies. The discrepancy might be partly related to earlier diagnosis in the post-ECLAP JAK2mutation era.2. Thrombotic events after diagnosisMedian follow-up was 6.9 years and treatment included aspirin (84%) and cytoreductive agents (73%), in addition to phlebotomy. Post-diagnosis total major thrombosis rate was 2.62% pt/yr, lower than reported in the ECLAP trial (4.4% pt/yr) but comparable to the Cyto-PV study (2.7% pt/yr) where management of cardiovascular risk factors was more intensive than in ECLAP.Arterial or venous thrombosis occurred in 184 (12%, rate: 1.59 % pts/yr) and 137 (9%, rate: 1.05 % pts/yr) patients, respectively. In addition, prior arterial events were associated in 75% of cases with subsequent arterial events and in the remaining 25% with venous thrombosis including splanchnic vein events. Moreover, patients with prior venous events had recurrences in venous district in 61% of cases and in the arterial district in 39%.3. Risk factors for arterial versus venous thrombosis and prognostic modelsIn multivariable analysis, arterial thrombosis was predicted by previous arterial event (HR 1.7, 95% CI 1.2-2.4), and hypertension (HR 1.6, 95% CI 1.2-2.2) while predictors of venous events were previous venous thrombosis (HR 2.6, 95% CI 1.5-4.4), and age ≥ 65 years (HR 1.7, 95% CI 1.2-2.5). We used the above-mentioned risk factors in order to develop prognostic models allowing to identify patients at different probability to develop arterial or venous thrombosis. For arterial thrombosis, the absence of previous arterial thrombosis and hypertension defined lower-risk (rate 1.27 % pts/yr) while the presence of one or both identified higher-risk patients (rate 2.04 % pts/yr). Previous venous event and/or age ≥ 65 years identified patients at higher risk of venous (rate 1.62 % pts/yr) thrombosis and, if absent, patients at lower risk (rate 0.78 % pts/yr).ConclusionThe overall rate of thrombosis was half than in ECLAP and should be considered in future clinical trials. Of note, patients with a prior venous thrombosis had a more frequent subsequent recurrence in the venous district but a proportion of them (40%) had also arterial events; conversely, recurrences after previous arterial event were also registered in the leg and non-leg veins in 30 % of cases, indicating that in PV, venous and arterial thrombosis may share some common pathogenetic mechanisms. These findings may have practical implications and suggests antiplatelet therapy and anticoagulant therapy as the favorite choice to prevent arterial and venous thrombosis, respectively, but also suggests studies of antithrombotic drug combination. DisclosuresNo relevant conflicts of interest to declare.

Changing Concepts of Diagnostic Criteria of Myeloproliferative Disorders and the Molecular Etiology and Classification of Myeloproliferative Neoplasms: From Dameshek 1950 to Vainchenker 2005 and Beyond

The Polycythemia Vera Study Group (PVSG) and WHO classifications distinguished the Philadelphia (Ph¹) chromosome-positive chronic myeloid leukemia from the Ph¹-negative myeloproliferative neoplasms (MPN) essential thrombocythemia (ET), polycythemia vera (PV) and primary myelofibrosis (MF) or primary megakaryocytic granulocytic myeloproliferation (PMGM). Half of PVSG/WHO-defined ET patients show low serum erythropoietin levels and carry the JAK2^V617F mutation, indicating prodromal PV. The positive predictive value of a JAK2^V617F PCR test is 95% for the diagnosis of PV, and about 50% for ET and MF. The WHO-defined JAK2^V617F-positive ET comprises three ET phenotypes at clinical and bone marrow level when the integrated WHO and European Clinical, Molecular and Pathological (ECMP) criteria are applied: normocellular ET (WHO-ET), hypercellular ET due to increased erythropoiesis (prodromal PV) and hypercellular ET associated with megakaryocytic granulocytic myeloproliferation (EMGM). Four main molecular types of clonal MPN can be distinguished: JAK2^V617F-positive ET and PV; JAK2 wild-type ET carrying the MPL⁵¹⁵; mutations in the calreticulin (CALR) gene in JAK2/MPL wild-type ET and MF, and a small proportion of JAK2/MPL/CALR wild-type ET and MF patients. The JAK2^V617F mutation load is low in heterozygous normocellular WHO-ET. The JAK2^V617F mutation load in hetero-/homozygous PV and EMGM is clearly related to MPN disease burden in terms of splenomegaly, constitutional symptoms and fibrosis. The JAK2 wild-type ET carrying the MPL⁵¹⁵ mutation is featured by clustered small and giant megakaryocytes with hyperlobulated stag-horn-like nuclei, in a normocellular bone marrow (WHO-ET), and lacks features of PV. JAK2/MPL wild-type, CALR mutated hypercellular ET associated with PMGM is featured by dense clustered large immature dysmorphic megakaryocytes and bulky (cloud-like) hyperchromatic nuclei, which are never seen in WHO-ECMP-defined JAK2^V617F mutated ET, EMGM and PV, and neither in JAK2 wild-type ET carrying the MPL⁵¹⁵ mutation. Two thirds of JAK2/MPL wild-type ET and MF patients carry one of the CALR mutations as the cause of the third distinct MPN entity. WHO-ECMP criteria are recommended to diagnose, classify and stage the broad spectrum of MPN of various molecular etiologies.

Complex karyotype in a polycythemia vera patient with a novel SETD1B/GTF2H3 fusion gene

The patient had been diagnosed with polycythemia vera (PV) in 1999, at the age of 61, according to the criteria of the Polycythemia Vera Study Group (PVSG) on the basis of the increased red cell mass by isotope determination, normal oxygen saturation, low plasma erythropoietin level, presence of endogenous erythroid colonies (EEC), and splenomegaly. Histopathology of bone marrow biopsy was also consistent with polycythemia vera with no evidence of increased reticulin fibrosis. A karyotype analysis was not performed at that time. He had been treated initially with phlebotomies and then with hydroxyurea with the aim to obtain a better control of hematocrit; he was under low-dose aspirin. In 2009, 10 years after the diagnosis, while the patient was still being treated with hydroxyurea and phlebotomies, he noticed worsening of general conditions and fatigue, and the appearance of night sweats; he also reported that his spleen volume had increased rapidly in the past few months. He complained of severe pruritus especially after (but not limited to) a shower. He was referred to our center for further evaluation. At presentation, his blood counts were as follows: hemoglobin 157 g/L, hematocrit 54.7%, leukocytes 13.1 × 10⁹ /L, platelets 238 × 10⁹ /L, LDH 856 U/L (normal upper limit, 250 U/L). Blood film examination showed neutrophilia (8.9 × 10⁹ /L) but immature myeloid cells and nucleated erythroblasts were absent. The spleen was 14 cm below the left costal margin, the liver was at 4 cm below the right costal margin. He was found to harbor the JAK2V617F mutation with an allele burden of 85% and the circulating CD34⁺ cell count was 14 × 10⁶ /L. A bone marrow biopsy showed the presence of hyperplasia of myeloid and erythroid lineages, increased number of scattered megakarocytes without overt morphologic abnormalities; reticulin fibrosis was grade 1 according to the European classification. On these basis, we considered the patient as presenting the features of PV according to the 2008 WHO classification of myeloid neoplasms associated with grade 1 reticulin fibrosis.

Application of the optimized CO-rebreathing method for determination of hemoglobin mass in patients with polycythemia vera

Determination of red cell volume (RCV) might contribute to establishing the diagnosis of polycythemia vera (PV). A novel simplified method to detect RCV through CO rebreathing is nowadays applied in healthy young individuals but was not tested in a clinical or PV setting. The aim of the present study is to evaluate whether this spirometric approach is applicable in older subjects and contributes to PV diagnosis in a proof-of-concept approach. At first, RCV was determined by the optimized CO-rebreathing method in healthy subjects >50years of age (n = 81, age 66 ± 9years). Failure rate and age distribution of subjects who failed with CO rebreathing were analyzed. Then, RCV was measured in male PV patients (n = 7) and compared to healthy male controls (n = 35). RCV values in relation to several anthropometric references (body weight, body surface area (BSA), lean body mass (LBM)) were calculated to determine the sensitivity and specificity of established RCV thresholds when using optimized CO rebreathing. In healthy subjects, test failure rate was 9.9%, but failure was not associated with age. Sensitivity and specificity (sens/spec) to detect PV was 100%/83% using the criteria of the PV study group. Using criteria based on BSA, sens/spec was 14%/100%. An arbitrary threshold of 50ml/kg LBM yielded sens/spec of 100%/97%. In conclusion, this proof-of-concept indicates that optimized CO rebreathing is applicable in older subjects and allows determining RCV for the diagnosis of PV. Normalized values for RCV measures obtained from CO rebreathing are needed to grant sufficient sensitivity and/or specificity.

Rethinking the diagnostic criteria of polycythemia vera

The aim of this review is to critically address the validity and clinical applicability of three major diagnostic classification systems for polycythemia vera (PV), that is, those proposed by the Polycythemia Vera Study Group (PVSG), the British Committee for Standards in Haematology (BCSH) and the World Health Organization (WHO). Special focus is on which one of the three red cell parameters (hemoglobin-HB, hematocrit-HCT and red cell mass-RCM) should be used as the diagnostic hallmark of PV. The revised BCSH employed a persistently raised HCT level as the first diagnostic criterion in combination with the presence of a JAK2V617F mutation. On the other hand, the WHO classification used a raised HB value as a surrogate for increased RCM in association with molecular markers and for the first time, the bone marrow (BM) morphology was included as a minor criterion. Ongoing controversy and discussion regards the use of certain threshold values for HCT and HB as surrogates for RCM as well as the existence of prodromal-latent disease, so-called masked PV (mPV). It has been shown that mPV can be recognized in patients not meeting the required HB or HCT threshold levels by both the WHO and BCSH criteria. These cases present with the same baseline clinical features as overt PV but present worsened survival. A critical reappraisal of the WHO criteria may suggest either to reduce the thresholds for HB or to consider HCT values as major diagnostic criterion, as in the BCSH, in association with JAK2V617F mutation. The clinical utility of using HCT as reference variable is supported also by results of clinical trials which explicitly recommend to use the HCT threshold for monitoring treatment. In questionable cases as in mPV, BM biopsy examinations should be mandated together with mutation analysis.

A prognostic model to predict survival in 867 World Health Organization–defined essential thrombocythemia at diagnosis: a study by the International Working Group on Myelofibrosis Research and Treatment

AbstractDiagnosis of essential thrombocythemia (ET) has been updated in the last World Health Organization (WHO) classification. We developed a prognostic model to predict survival at diagnosis, named IPSET (International Prognostic Score for ET), studying patients with WHO-defined ET. Age 60 years or older, leukocyte count ≥ 11 × 109/L, and prior thrombosis significantly affected survival, by multivariable Cox regression. On the basis of the hazard ratio, we assigned 2 points to age and 1 each to leukocyte count and thrombosis. So, the IPSET model allocated 867 patients into 3 risk categories with significantly different survival: low (sum of points = 0; median survival not reached), intermediate (sum = 1-2; median survival 24.5 years), and high (sum = 3-4, median survival 13.8 years). The IPSET model was further validated in 2 independent cohorts including 132 WHO-defined ET and 234 Polycythemia Vera Study Group–defined ET patients. The IPSET model was able to predict the occurrence of thrombosis, and not to predict post-ET myelofibrosis. In conclusion, IPSET, based on age ≥ 60 years, leukocyte count ≥ 11 × 109/L, and history of thrombosis allows prognostic assessment of WHO-defined ET and the validation process makes IPSET applicable in all patients phenotypically appearing as ET.

Thrombocythemia and polycythemia in patients younger than 20 years at diagnosis: clinical and biologic features, treatment, and long-term outcome

AbstractSixty-four patients < 20 years of age, investigated for a suspicion of Philadelphia-negative myeloproliferative disease (MPD), were retrospectively evaluated to characterize the different forms and to examine the treatments used and long-term outcome. JAK2 mutations, endogenous erythroid colony growth, and clonality were investigated in 51 children. Mutations of thrombopoietin, the thrombopoietin receptor (MPL), and the erythropoietin receptor and mutations of other genes involved in the pathogenesis of MPD were investigated in JAK2 wild-type patients. Based on our criteria for childhood MPD, we identified 34 patients with sporadic thrombocythemia (ST), 16 with hereditary thrombocytosis (HT), 11 with sporadic polycythemia (SP), and 3 with hereditary polycythemia (HP). JAK2V617F mutations were present in 47.5% of ST and in no HT. The MPLS505A mutation was detected in 15/16 HT patients and in no ST (P < .00001). The JAK2V617F mutation occurred in 27% of SP patients diagnosed according to the Polycythemia Vera Study Group or World Health Organization 2001 criteria. Children with ST received more cytoreductive drugs than those with HT (P = .0006). After a median follow-up of 124 months, no patient had developed leukemia or myelofibrosis and 5% had thrombosis; the miscarriage rate in thrombocythemic patients was 14%. The low complication rate in our population suggests that children with MPD may be managed by tailored approaches.

Decrease in JAK2V617F allele burden is not a prerequisite to clinical response in patients with polycythemia vera

Although reduction in the JAK2(V617F) allele burden (%V617F) has been suggested as a criterion for defining disease response to cytoreductive therapy in polycythemia vera, its value as a response monitor is unclear. The purpose of this study is to determine whether a reduction in %V617F in polycythemia vera is a prerequisite to achieving hematologic remission in response to cytoreductive therapy. We compared the clinical and hematologic responses to change in %V617F (molecular response) in 73 patients with polycythemia vera treated with either interferon (rIFNα-2b: 28, Peg-rIFNα-2a: 18) or non-interferon drugs (n=27), which included hydroxyurea (n=8), imatinib (n=12), dasatinib (n=5), busulfan (n=1), and radioactive phosphorus (n=1). Hematologic response evaluation employed Polycythemia Vera Study Group criteria, and molecular response evaluation, European Leukemia Net criteria. Of the 46 treated with interferon, 41 (89.1%) had a hematologic response, whereas only 7 (15.2%) had a partial molecular response. Of the 27 who received non-interferon treatments, 16 (59.3%) had a hematologic response, but only 2 (7.4%) had a molecular response. Median duration of follow up was 2.8 years. Statistical agreement between hematologic response and molecular response was poor in all treatment groups. Generally, hematologic response was not accompanied by molecular response. Therefore, a quantitative change in %V617F is not required for clinical response in patients with polycythemia vera.

Survival and Prognosis Among 1,263 Patients with Polycythemia Vera: An International Study

Abstract▪277▪This icon denotes a clinically relevant abstract Background:Current information on the natural history of polycythemia vera (PV) is mostly derived from early studies based on the PV Study Group diagnostic criteria. The World Health Organization (WHO) diagnostic approach to PV is currently the gold standard. The main objective of the current study was to describe survival, disease complication rates and risk factors in WHO-defined PV. Methods:Under the auspices of an International Working Group, seven international centers of excellence for myeloproliferative neoplasms submitted a total of 1,430 patients, locally diagnosed with “WHO-defined PV”. The two principle investigators (AT and TB) reviewed all the cases and selected 1,263 patients who were age 18 years or older, diagnosed after 1970, and whose submitted data included diagnostically essential information. Results I: Presenting Features:Median age was 60 years (range, 18–95; 51% females). The number of patients diagnosed between 1970–1990, 1991–2000, and 2001–2011 were 136 (11%), 337 (27%) and 790 (62%), respectively. Arterial/venous thrombosis history before or at diagnosis was documented in 142/73 and 80/42 patients, respectively. Other features at diagnosis included pruritus (37%), microvascular disturbances (29%), palpable splenomegaly (37%), abnormal karyotype (13%), and leukoerythroblastosis (6%). History of hypertension (45%), hyperlipidemia (17%), diabetes (9%), and tobacco use (15%) was also obtained. Results II: Clinical Course:To date, 228 (18%) deaths, 42 (3%) leukemic progressions, and 101 (8%) fibrotic transformations have been recorded. Post-diagnosis arterial or venous thrombosis occurred in 139 (11%) and 85 (7%) patients, respectively. Cytoreductive therapy had not been used in 342 (27%) patients whereas 154 (12%) patients were exposed to two or more cytoreductive drugs. Results III: Risk Factors:Multivariable analysis identified advanced age, leukocytosis, venous thrombosis history and abnormal karyotype as significant (p<0.01) risk factors for overall survival (OS). Receiver operating characteristic (ROC) plots delineated ages 69 (AUC 0.83) and 59 (AUC 0.61) years and leukocyte count 13 × 109/L (AUC=0.61) as the best discriminant levels in this regard; HR (95% CI) were 11.4 (7.7–16.9) for age ≥70 years, 3.8 (2.6–5.7) for age 60–69 years, and 2.0 (1.5–2.6) for leukocyte count ≥15 × 109/L. Results IV: Risk Stratification:HR-based risk scores were assigned to age ≥70 years (3 points), age 60–69 years (2 points) and leukocyte count ≥15 × 109/L (one point), in order to create four risk groups: low (zero points; n=492; median survival 322 months), intermediate-1 (one or 2 points; n=353; median survival 208 months; HR 3.8, 95% CI 2.5–5.8), intermediate-2 (3 points; n=286; median survival 132 months; HR 10.7, 95% CI 6.9–16.5), and high (4 points; n=56; median survival 90 months; HR 22.7, 95% CI 13.9–37.1) (Figure 1). Similar results were obtained when analysis was restricted to the 1,011 JAK2 mutation-positive patients (Figure 2). The particular risk model was equally robust in predicting leukemia-free survival (p=0.001). [Display omitted] Conclusions:Age and leukocyte count matter the most in predicting survival in PV. The current study suggests additional prognostic value from karyotype and venous thrombosis history. [Display omitted] Disclosures:Vannucchi:Novartis: Honoraria. Gisslinger:Novartis: Speakers Bureau; Celgene Austria: Speakers Bureau; AOP-Orphan: Speakers Bureau.

Thrombin Generation In Patients with Essential Thrombocythemia Treated with Anagrelide

AbstractAbstract 5050 Introduction:Thrombosis may be serious and life threatening in patients with essential thrombocythemia (ET). Bleeding is usually from the gastrointestinal tract, and is, in most cases, generally associated with a platelet count greater than 1 million/μL. The mechanism by which thrombocythemia produces hemorrhage or thrombosis is not well defined. Several defects have been described, including a decrease in platelet aggregation or hyperaggregation, a decrease in von Willebrand ristocetin cofactor activity and high molecular weight von Willebrand factor multimers. Some reports show patients with an acquired deficiency of antithrombin, protein C, and acquired APC resistance, probably due to a reduction in free protein S levels. More recently the presence of JAK2V617F mutation and baseline leukocyte (WBC) count have been considered as independent predictors of major thrombosis in ET. Aim of the study:To assess the thrombin generation by the calibrated automated thrombogram method in plasma from ET patients treated with anagrelide. This assay reflects the net results of the procoagulant and anticoagulant forces operating in plasma. The area under the thrombin generation curve (also known as the endogenous thrombin potential (ETP) is a good overall indicator of prothrombotic and hemorrhagic tendency. It could be hypothezised, that platelet-lowering treatment could diminish haemostasis disturbances in ET. Material and methods:The study group consisted of ten ET patients (4 males and 6 females; age range, 24–70 years), diagnosed according to the Polycythemia Vera Study Group criteria. All patients have been treated with anagrelide for mean 4 years (range 1 – 7 years), without antiplatelet drugs. At the time of enrollment their mean platelet number was 344 000/μL (210 000 – 535 000), WBC count 8 600/μL (3 300 – 9 800), and hematocrit 38 (33-47). One patient had a history of splenic vein thrombosis, another had a gastrointestinal bleeding before the start of treatment. Four ET patients (40%) were positive for the JAK2V617F. Ten healthy subjects (4 males and 6 females; age range, 30–70 years) without history of thrombohemorrhagic events, acted as a control group. Thrombin generation (TG) was determined by calibrated automated thrombography (Technothrombin TGA-Technoclone). Thrombin generation curves were described in terms of lag time, peak height, time to peak, slope and ETP. Whole blood thromboelastometry with TEM-ROTEM delta - Pentapharm GmbH has been performed as well. Results:Thrombin generation (ETP) in platelet free plasma was significantly increased in patients with ET (2235 ± 376 nM/min) in comparison with controls (1631 ± 257 nM/min; p=0,0082), the TG lag time, peak, time to peak and slope were also abnormal. Patients with ET showed markedly increased values of INTEM coagulation time-CT, clot formation time-CFT and increased maximum clot firmness, when compared to results of the control group (Table). There were no differences in the EXTEM values. Conclusion:Our results suggest that patients with essential thrombocythemia, in spite of a long-lasting anagrelide treatment, still exhibit an increased thrombin generation as well as formation of a clot with an increased firmness.INTEMCT (sec)CFT (sec)MCF (mm)A10 (mm)A15 (mm)A20 (mm)ET n=10182,1 ± 16,1 p = 0,001145,4 ± 6,34 p = 0,000770,5 ± 2,83 p = 0,00765,6 ± 3,44 p = 0,00268,5 ± 3,17 p = 0,00469,9 ± 3,03 p = 0,007Contr. n=10161,7 ± 11,862,3 ± 9,5464,1 ± 4,9368,5 ± 3,6862,2 ± 3,9363,5 ± 4,55 Disclosures:No relevant conflicts of interest to declare.

Practical application and clinical impact of the WHO histopathological criteria on bone marrow biopsy for the diagnosis of essential thrombocythemia versus prefibrotic primary myelofibrosis

To evaluate the feasibility of the histopathological diagnosis of prefibrotic-early primary myelofibrosis (PM) as described in the World Health Organization (WHO) classification and to evaluate the clinical implications of prefibrotic-early PM in a series of patients previously diagnosed as having essential thrombocythemia (ET) according to the Polycythemia Vera Study Group criteria. WHO criteria were applied to bone marrow biopsy specimens by two pathologists who then reclassified 127 cases as 102 ET (80.3%), 18 prefibrotic-early PM (14.2%) and seven fibrotic PM (5.5%). In 45 cases (35%), the final diagnosis was only reached by consensus. The megakaryocytic criteria that best discriminated between ET and prefibrotic-early PM were an increased nucleo-cytoplasmic ratio, presence of cloudlike nuclei, hyperchromatic-dysplastic nuclei, paratrabecular megakaryocytes and tight clusters. A histological score discriminated between ET (score < or =3) and PM (score > or =6), but 21 cases showed an intermediate ambiguous score. No significant differences were observed at diagnosis and at follow-up (median time 93 months) for thrombosis, major haemorrhage, laboratory data, transformation into overt myeloid metaplasia and survival. The distinction between ET and prefibrotic-early PM is impaired by subjectivity in pathological practice and is of questionable clinical relevance, at least when considering individual patients.

Decrease in JAK2V617F Allele Burden is Not a Prerequisite to Clinical Response in Patients with Polycythemia Vera (PV).

Abstract 1908Poster Board I-931Previous studies of patients (pts) with polycythemia vera (PV) treated with pegylated interferon (peg-IFNá-2a) have shown an 83% complete hematologic response associated with an 89% molecular response over a median of 11 months (Kiladjian et al. Blood. 2008. 112(8):3065-3072) implying a causative relationship between molecular and hematologic responses. Our data show pts treated with rIFNá-2b or non-rIFNá-2b agents achieve hematologic response despite the absence of a molecular response suggesting that a molecular change is not a prerequisite to hematologic response.Thirty pts diagnosed with PV by the criteria of the Polycythemia Vera Study Group (PVSG) were followed clinically and hematologically with serial quantified JAK2V617F allele burden determined at six-month intervals over a mean of 21.6 months (mos) (range: 6.0 – 56.4 mos). These pts were treated with rIFNá-2b ranging from 0.5 mu to 3.0 mu three times per week depending upon clinical response. Primary clinical endpoints were hematocrit (hct) ≤45% men, ≤42% women, and no need for phlebotomy (PHL). Molecular and hematologic responses were graded according to the criteria of Barosi et al. (Blood. 2009. 113(20):4829-4833): complete hematologic response (CHR: hct ≤45% without PHL, platelets '400×109/L, WBC ≤10×109/L, normal spleen size, asymptomatic); partial hematologic response (PHR: hct ≤45% without PHL or response in 3 or more of the CHR categories); no hematologic response (NHR: failure to meet the criteria of CHR or PHR); complete molecular response (CMR: reduction of JAK2V617F marker to undetectable levels); partial molecular response (PMR: ≥50% reduction in pts with '50% mutant allele burden at baseline, or ≥25% reduction in pts with >50% mutant allele burden at baseline; applicable only to pts with ≥10% baseline allele burden); and no molecular response (NMR: failure to meet the criteria of CMR or PMR).Of the 30 pts treated with rIFNá-2b, 14 had a CHR, 13 had a PHR and 3 had NHR. Of 14 pts who had a CHR, 4 had a PMR and 10 had NMR. Of thirteen pts who had a PHR, 1 had a PMR and 12 had NMR. All 3 pts who had NHR also had NMR. Based on these data, the statistical agreement between hematologic response and molecular response was poor (kappa coefficient = 0.06, P=0.17).We then examined the hematologic responses (HR: CHR+PHR) of 25 non-rIFNá-2b treated pts, which included PHL ± anagrelide (3 pts: 2 HR/NMR, 1 NHR/NMR), dasatinib (5 pts: 5 HR/NMR), imatinib (9 pts: 3 HR/PMR, 4 HR/NMR, 2 NHR/NMR), and hydroxyurea (8 pts: 1 CHR/PMR, 7 HR/NMR). The minimal molecular response to dasatinib and hydroxyurea is noteworthy. Likewise, there was poor statistical agreement between hematologic response and molecular response for non-rIFNá-2b treated patients (kappa coefficient = 0.05, P=0.21).Of all 55 pts (rIFNá-2b and non-rIFNá-2b), those 9 patients with a PMR had a hematologic response (7 CHR and 2 PHR). Of 46 NMR's, 40 pts (87%) had a hematologic response (16 CHR, 24 PHR). Thus, NMR did not exclude the possibility of achieving CHR. Regardless of therapy, we demonstrate poor agreement between hematologic and molecular responses for these drugs (all pts: kappa = 0.05, P=0.13). This suggests a difference in action between peg-IFNá-2a, shown to cause molecular and hematologic responses concurrently, and several drugs we examined leading to clinical response without necessarily changing JAK2V617F allele burden. In this regard, other parameters such as bone marrow morphology and new biological markers may be useful in reconciling the differences.In summary, we find that a hematologic response is not always accompanied by a molecular response in PV pts treated with either rIFNá-2b or some non-rIFNá-2b drugs. We thus conclude that a reduction in JAK2V617F allele burden is not always required for patients to achieve hematologic response, and that following the JAK2V617F biomarker may be drug-dependent and may not always be a reliable measure of response. This warrants the importance of the randomized trial planned to compare peg-IFNá-2a to the current standard of treatment, hydroxyurea. Disclosures:No relevant conflicts of interest to declare.

The WHO's who of haematopoietic malignancies

The WHO's who of haematopoietic malignancies

Essential thrombocythemia in patients with platelet counts below 600x109/L: Applicability of the 2008 World Health Organization diagnostic criteria revision proposal

The World Health Organization (WHO) diagnostic criteria as well as the Polycythemia Vera Study Group (PVSG) criteria define platelet counts above 600x10 9 /L as the threshold for essential thrombocythemia (ET) diagnosis [1,2]. It has been argued that such threshold excludes a number of patients with actual ET with platelet counts below 600 x 10 9 /L [3-5]. Recently, a proposal for revision of the WHO diagnostic criteria for ET has been published, which includes the combination of histological bone marrow study and testing of the JAK2 mutation to facilitate the diagnosis of ET with borderline thrombocytosis [6,7]. The aim of this study was to evaluate the applicability of the proposal of the WHO revised diagnostic criteria in patients presumed to have ET with platelet counts below 600 x 10 9 /L. Additionally, clinical and laboratory features of this group were compared to the group with platelet counts above 600 x 10 9 /L to assess any differences between both groups. Finally, clinical and laboratory features of JAK2 positive patients were compared to JAK2 negative patients to confirm in our series the differences previously described in the literature [8,9].

Myelofibrotic transformation in essential thrombocythemia

The exact incidence of myelofibrotic transformation in essential thrombocythemia (ET) is still a critical issue1,2 and is certainly influenced by risk status and diagnostic criteria. In a recently published study by Passamonti and co-workers in this journal,3 a cohort of 605 patients with ET is described recruited during a lengthy period (1975 to 2008) from one center. Unfortunately, as explicitly stated, diagnosis of ET was performed using criteria at the time of the first observation, implicating that a large fraction, probably the majority of patients, were diagnosed by following the cited criteria of the Polycythemia Vera Study Group (PVSG),4 contrasting the more recently entered fraction to whom the WHO classification was applied.5 Consequently, the diagnostic guidelines are inconsistent regarding a strict differentiation of ET from early stages of primary myelofibrosis (PMF) with associated thrombocytosis. It has been demonstrated by different groups that significant differences exist between the PVSG versus the WHO classification schemes for ET: depending on risk factors and selection of patients only about 20–40% of ET cases diagnosed according to the PVSG4 are validated by the WHO criteria.6–8 The diagnosis of post-ET myelofibrosis was made by the authors using the criteria of the International Working Group on Myelofibrosis (IWG-MRT).9 However, these criteria do explicitly include as first major requirement the documentation of a previous diagnosis of WHO-defined essential thrombocythemia . This postulate can not be fulfilled by the obviously predominant PVSG-diagnosed series of patients incorporated into this investigation. Moreover, following the IWG-MRT criteria, bone marrow fibrosis grade 2–3 consistent with the cited European Consensus Grading System10 is the second major requirement. This important feature implicates the evaluation of sequential bone marrow biopsy specimens - has this been performed in all patients under study? Concerning the frequency of post-ET myelofibrosis, the transformation rate was 2.8% at a median follow-up of 9.1 years (or a 10-year risk of 3.9% and a 15-year risk of 6%).3 This relatively low incidence may possibly be created by including an unknown number of WHO-diagnosed ET cases into this study. When strictly following the diagnostic criteria of the PVSG4 applied in the UK-PT1 Study for high risk ET,11 in our retrospective evaluation of 539 patients under standard therapy, after three years overall incidence of myelofibrosis proved to be significantly different depending on diagnostic criteria (Table 1). Table 1. Risk of myelofibrotic transformation (post-essential thrombocythemia myelofibrosis) within 36 months in 539 high-risk patients with essential thrombocythemia strictly diagnosed according to the UK-PT1 Study criteria11 receiving standard therapy regimens. ... This difference was generated by discrimination of the total cohort according to the WHO classification5 into (true) ET and PMF with accompanying thrombocytosis mimicking this condition. On the other hand, when maintaining the PVSG guidelines,4 a comparable rate (2.8% vs. 2.6%)11 of progression into myelofibrosis was revealed during an observation time of about three years. Regarding leukemic transformation, although no systemic study has yet been published, similar discrepancies associated with applied classification schemes may be encountered. In conclusion, a thorough re-evaluation of this series of 605 patients with distinction into those diagnosed as ET cases according to PVSG criteria4 versus those in whom diagnosis was based on the WHO classification seems to be warranted, including a repeatedly performed calculation of progression rates into myelofibrosis and leukemia. As criteria for myelofibrotic transformation, the corresponding guidelines of the UK-PT1 Study11 should be used for the presumably prevalent ET group diagnosed after PVSG, and for the WHO classified series the IWG-MRT parameters can be applied. As has been reviewed for myelofibrosis in chronic myeloproliferative neoplasms,12 a significant difference between both groups of patients can be predicted consistent with the diagnostic criteria applied.

Thrombotic complications of polycythemia vera

Background: Polycythemia vera (PV) is an uncommon clonal disorder of stem cells. The literature regarding the thrombotic complications of this disorder in the developing countries is scarce. The present study was undertaken retrospectively to look at the association of thrombotic complications of PV with various patient characteristics.Materials and methods: All the patients diagnosed to have PV from January 1986 to December 2005 according to Polycythemia Vera Study Group criteria were included. Their clinical characteristics, laboratory parameters, clinical complications such as thrombosis and myelofibrosis, treatment modalities, malignancies and deaths, if any were noted. The various characteristics of patients who had developed thrombosis were compared statistically with those of patients without thrombosis.Results: Out of the 9550 patients seen during this period, 32 patients fulfilled the inclusion criteria. The median age at the time of diagnosis was 56·5 years. Eight patients developed thrombotic complications; out of which four had arterial and four had venous thrombosis. There was no statistically significant difference in the mean hemoglobin, white cell count (WBC), platelet count and RBC mass in patients with thrombosis as compared to patients without thrombosis. These parameters were also not statistically significant when patients with arterial thrombosis were compared with patients with venous thrombosis.Conclusions: PV is an uncommon disorder when compared with other hematological disorders in northern India. There was no relationship between the development of thrombotic complications and hemoglobin, RBC mass or platelet count. Twenty patients received hydroxyurea with a median follow-up of 57 months, none developed acute leukemia.