True Essential Thrombocythemia Research Articles

PB2225 ARTIFICIAL INTELLIGENCE AIDING IN DIAGNOSIS OF JAK2 V617F NEGATIVE PATIENTS WITH WHO DEFINED ESSENTIAL THROMBOCYTHEMIA

Background:Smart Blood Analytics (SBA) is an artificial intelligence program using machine learning algorithm in order to provide a list of most probable disease diagnosis in numerical order based on patient's blood test results. It was successfully tested in diagnosing hematological diseases and is especially targeted for medical doctors without detailed knowledge in the field of hematology.Aims:Our aim was to determine the applicability of SBA algorithm in patients with suspected essential thrombocythemia (ET).Methods:We analyzed 237 patients that presented at UMC Ljubljana between 04/2011 and 09/2016 with the referral diagnosis of ET. Based on the presence of CALR or MPL mutation and bone marrow examination we defined patients with true ET according to WHO 2008 or modified WHO criteria. All 237 patients were subsequently analyzed by SBA algorithm in order to determine the most probable hematologic diagnosis based on patients’ blood test results obtained at the time of referral. The diagnosis of interest according to ICD10 classification was D47 describing other neoplasms of uncertain behavior of lymphoid, hematopoietic and related tissue, including ET. We defined sensitivity and specificity of ET diagnosis by using SBA machine learning algorithm.Results:10.5% (25/237) of patients were diagnosed with ET according to WHO 2008 or modified WHO criteria. 22 patients were CALR positive, 1 patient was MPL positive and 3 patients were triple negative. 89.4% (212/237) of patients were diagnosed with either secondary thrombocythemia or other neoplastic disease, such as myelodysplastic syndrome. The sensitivity of SBA algorithm to detect patients with ET was 100% and the specificity was 50.4%.Summary/Conclusion:The number of patients with true ET referred to our center was low. An improved referral and diagnostic approach for patients with thrombocythemia should be used. The SBA machine learning algorithm could be useful, especially in circumstances where hematologic consultation is not available. Further development of SBA machine learning algorithm is warranted.

Clinical and molecular features of patients with prefibrotic primary myelofibrosis previously diagnosed as having essential thrombocythemia in Japan.

Prefibrotic/early primary myelofibrosis (pre-PMF) and essential thrombocythemia (ET) exhibited different features of bone marrow; however, this is not always easy to judge objectively, making pathologists' distinction often suboptimal. In the WHO 2008 criteria, pre-PMF was not defined as a subgroup of PMF; therefore, affected patients were at a higher risk of misdiagnosis with ET. In this study, we examined the prevalence of pre-PMF patients among those previously diagnosed with ET in Japan. We reviewed bone marrow specimens and clinical and molecular parameters of patients who were previously diagnosed with ET by the WHO 2008 criteria. Among 107 ET patients, 13 patients were redefined as having pre-PMF. Pre-PMF patients exhibited a higher frequency of MPL mutation and increased platelet counts compared to true ET patients. Molecular analysis revealed the frequencies of high-risk molecular mutations, such as ASXL1, EZH2, and SRSF2, were significantly increased in pre-PMF patients than those in true ET patients. These results demonstrated the value of reexamining clinical records for patients diagnosed with ET by the WHO 2008 criteria and emphasized that adequate examinations of patients' bone marrow are crucial for an accurate diagnosis of pre-PMF and ET.

MPL-Mutated Essential Thrombocythemia: A Morphologic Reappraisal

Background:Myeloproliferative leukemia virus oncogene (MPL)-mutated essential thrombocythemia (ET) is uncommon, with a cited incidence of less than 5%, while that of MPL-mutated primary myelofibrosis (PMF) is at least twice as frequent (Blood. 2006;108:3472;Blood.2008;112:141). MPL-mutated ET cohorts also have higher reported rates of fibrotic progression than their MPL wild type counterparts (Blood. 2014;124:2507). These observations suggest the possibility that some instances of MPL-mutated ET might actually represent prefibrotic PMF.Methods:Patients were recruited from institutional databases of the Mayo Clinic, Rochester, MN, USA. Diagnoses were according to the 2016 World Health Organization (WHO) criteria (Blood. 2016;127:2391). Study inclusion criteria required the availability of bone marrow biopsy slides for central review by one of the authors (C.A.H.). Central pathology review included assessment of bone marrow cellularity and extent of tri-lineage proliferation, megakaryocyte morphology and grading of reticulin fibrosis. Data was additionally collected from MPL-mutated patients with PMF, for comparison. Standard statistical methods were used for statistical analysis, including calculation of survival data (JMP® Pro 13.0.0, SAS Institute, Cary, NC, USA).Results:A total of 665 patients with ET were annotated for their driver mutational status; 18 (2.7%) were reported out as being MPL-mutated; by comparison, among 867 patients with PMF, 47 (5.4%) were signed out as MPL-mutated. Among the 18 cases with MPL-mutated ET, bone marrow slides were available for central pathology review in 14 patients (Table 1). The latter were subsequently reassigned the diagnosis of either prefibrotic PMF (n=8; 57%) or were felt to be morphologically consistent with true WHO-defined ET (n=6; 43%). Comparison of these two distinct histopathological patterns, i.e. true ET vs reassigned prefibrotic PMF, was respectively characterized by lower (median 35%, range 30-50) vs higher (median 65%, range 40-80) bone marrow cellularity (P<0.001), ET (n=6) vs PMF (n=8) consistent megakaryocyte morphology (P<0.001) and presence of tri-lineage proliferation (0% vs 100%; P<0.001); in contrast the degree of reticulin fibrosis was similar between the two (P=0.1) (Table 2).The reassigned prefibrotic PMF (n=8), vs confirmed ET (n=6), cases also displayed a higher frequency of increased serum levels of lactate dehydrogenase (60% vs 0%; P=0.02), higher likelihood of displaying hemoglobin levels below the sex-adjusted reference range values (29% vs 0%; P=0.1), leukoerythroblastosis (14% vs 0%; P=0.2), constitutional symptoms (13% vs 0%; P=0.2) and a higher incidence of thrombosis history at presentation (38% vs 0%; P=0.04) (Table 2). Interestingly, reassigned prefibrotic PMF also displayed a narrower MPL mutational spectrum compared to those confirmed as ET (MPLW515L/K incidence 100% vs 60%; P=0.04). The incidences of abnormal karyotype and high risk molecular mutations (ASXL1, SRSF2 and U2AF1) were similar between the two.We documented a higher incidence of post-diagnosis thrombosis in prefibrotic PMF (25% vs 0%; P=0.1) but similar rates of leukemic transformation (0% for both) and fibrotic progression (38% vs 33%); when all 665 ET patients were assessed for myelofibrosis-free survival, MPL-mutated cases (prior to central review) displayed significantly worse outcome, compared to patients with other driver mutations (Figure 1a). Median overall survival in confirmed MPL-mutated ET, ET re-classified as PMF, and MPL-mutated PMF was not reached, 11.6 and 5.3 years, respectively (confirmed ET vs PMF, P=0.01; ET re-classified vs PMF, P=0.04; confirmed ET vs ET re-classified as PMF, P=0.54) (Figure 1b).Conclusions:The current study suggests that the majority of routinely-assigned MPL-mutated ET probably represents prefibrotic PMF, when morphologically scrutinized. Prior to central pathology review, we show a higher rate of fibrotic progression in MPL-mutated ET, compared to patients with other driver mutations; accordingly, after central pathology review, the similar rate of fibrotic progression between morphologically confirmed MPL-mutated ET and those reassigned as prefibrotic PMF further suggests the latter to be biologically more akin to PMF, despite its ET-consistent morphologic features. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

A 7-Gene Signature Depicts the Biochemical Profile of Early Prefibrotic Myelofibrosis.

Recent studies have shown that a large proportion of patients classified as essential thrombocythemia (ET) actually have early primary prefibrotic myelofibrosis (prePMF), which implies an inferior prognosis as compared to patients being diagnosed with so-called genuine or true ET. According to the World Health Organization (WHO) 2008 classification, bone marrow histology is a major component in the distinction between these disease entities. However, the differential diagnosis between them may be challenging and several studies have not been able to distinguish between them. Most lately, it has been argued that simple blood tests, including the leukocyte count and plasma lactate dehydrogenase (LDH) may be useful tools to separate genuine ET from prePMF, the latter disease entity more often being featured by anemia, leukocytosis and elevated LDH. Whole blood gene expression profiling was performed in 17 and 9 patients diagnosed with ET and PMF, respectively. Using elevated LDH obtained at the time of diagnosis as a marker of prePMF, a 7-gene signature was identified which correctly predicted the prePMF group with a sensitivity of 100% and a specificity of 89%. The 7 genes included MPO, CEACAM8, CRISP3, MS4A3, CEACAM6, HEMGN, and MMP8, which are genes known to be involved in inflammation, cell adhesion, differentiation and proliferation. Evaluation of bone marrow biopsies and the 7-gene signature showed a concordance rate of 71%, 79%, 62%, and 38%. Our 7-gene signature may be a useful tool to differentiate between genuine ET and prePMF but needs to be validated in a larger cohort of “ET” patients.

Thrombotic risk correlates with mutational status in true essential thrombocythemia

True essential thrombocythemia (ET) may carry one of the known driver mutations (JAK2, MPL and CALR) or none of them [in triple-negative (3NEG) cases]. The patients' mutational status seems to delineate the clinical manifestations of ET. We report the data of 183 patients diagnosed with ET strictly according to the WHO 2008 criteria and with a full molecular diagnosis, including the following: 114 patients (62·3%) with JAK2V617F; 25 (13·7%) with CALR type 1 and 19 (10·4%) with CALR type 2; 3 (1·6%) with MPL; 22 (12%) who were 3NEG. Thrombotic risk was assessed by means of the IPSET-thrombosis score (IPSET-T). CALR and 3NEG patients had lower haemoglobin levels and leucocyte count than JAK2 patients. CALR patients, and those with type 2 in particular, had higher mean platelet counts and had extreme thrombocytosis more often than any of the other groups. Based on their IPSET-T stratification, 3NEG- and CALR-mutated patients belonged more frequently to the low-risk group and had a significant more favourable thrombosis-free survival rate than those with JAK2 mutation. These findings indicate that the three different molecular markers have a significant impact on the clinical course of true ET, giving rise to different phenotypes of the same disease.

Advances and challenges in the management of essential thrombocythemia.

The new World Health Organization (WHO) diagnostic criteria for essential thrombocythemia (ET) issued in 2008 made an important distinction between true ET and early myelofibrosis (MF), which has helped to identify a more homogenous population for the diagnosis with longer survival and much less transformation to overt MF. The recent finding of a new mutation (CALR), which is mutually exclusive with JAK2 and MPL mutations, adds to the characterization of ET patients, since there are important phenotypic differences between the mutation types. CALR patients are younger, have lower white blood cell counts (WBC) and a lower thrombosis incidence. A growing field of interest is the state of hypercoagulation due to dysfunction of hemostatic systems, cell-cell interaction and hereditary prothrombotic traits. Activation of platelets, WBC and endothelial cells has been found, making the whole intravascular milieu prothrombotic. Several risk score models, based on retrospective studies, have been developed lately, distinguishing patient groups with graded risk for complications and death. Even if these may be helpful in evaluating patients, they have not been validated in prospective studies and there are not enough data to support their use as a basis for treatment algorithms. The traditional risk factors age, previous thrombosis and platelets >1500 × 10(9)/l are still recommended for the distinction between high risk and low risk ET and the decision to give cytoreductive therapy. However, cardiovascular (CV) risk factors add to thrombosis risk and should be considered both for specific treatment in any risk group and for upgrading low risk patients with high CV risk to an intermediary group where active therapy with aspirin and cytoreduction may be considered. First-line cytoreductive therapy differs with age; in younger patients interferon (IFN) or anagrelide are preferable, in older patients hydroxycarbamide (HC). Second-line therapy for younger patients is HC, for older patients IFN or anagrelide (ANA). JAK2 inhibitors may be suitable in rare cases with symptoms not responding to other therapy.

Mutations and Long-Term Outcome of 217 Young Patients with Essential Thrombocythemia or Early Primary Myelofibrosis

IntroductionYoung adults with Essential Thrombocythemia (ET) or early Primary Myelofibrosis (early-PMF) are a category of patients projected to a prolonged survival but also to an extended utilization of medical resources. Mutations, including those in the calreticulin (CALR) gene, have been reported to affect main clinical features and outcome in large cohorts of patients with Ph-negative MPNs. However, no data are available on mutational status and long-term outcome in young MPN patients.MethodsA clinic-pathologic database of ET patients followed in 5 Italian Hematology Centers was created. A total of 217 WHO-diagnosed ET or early-PMF patients ≤ 40 years at diagnosis was retrieved from the general database of 2635 patients. All bone marrow biopsies were reviewed at local institution. Baseline clinical/molecular characteristics and outcome measures (thrombosis, hemorrhages, secondary MF and AL, second neoplasia, death, overall and event-free survival) were evaluated. JAK2V617F allele-burden was assessed in granulocyte DNA by using ipsogen JAK2 MutaQuant Kit (qPCR). CALR mutations were identified by next generation sequencing (NGS) approach on GS Junior (Roche-454 platform); MPL mutations were evaluated by using ipsogen MPLW515L/K MutaScreen Kit.ResultsOverall, 197 WHO-defined ET and 20 early-PMF (age range: 16-40, median 34) were included in the study. Mutational frequencies were 61% for JAK2, 25% for CALR, 1% for MPL and 13% for triple negative. Baseline clinical characteristics and use of antiplatelet/cytoreductive therapies were comparable in ET and early-PMF, although frequency of triple negative was higher in the early-PMF cohort.Compared to the JAK2 positive population, both CALR and triple-negative patients showed higher platelet count and lower hemoglobin and hematocrit levels (Table 1).Median follow-up was 10.2 years (range: 0.5-37.5). During follow-up, 19 (9,6%) ET and 3 (15%) early-PMF patients experienced a total of 31 thrombotic (arterial: 38%) and 12 hemorrhagic events, with an incidence rate of 0.91% and 0.39% patients/yr, respectively. The cumulative incidence of thrombosis was 0,14% and 0,24% at 15 and at 20 years, respectively.Overall, 10 patients (4,6%) and 1 (0,4%) patients evolved to MF and AL, respectively; 10 developed a second neoplasia. The cumulative incidence of disease progression into MF/AL was 0,03% and 0,13% at 15 and at 20 years, respectively. At last contact, 6 (2,7%) patients had died, at a median age of 61 years (20-71), for an overall survival of 98% at 15 years. Causes of death were related to the myeloproliferative neoplasm (disease evolution or thrombotic complications) in all patients but one. Event-free survival was similar in the ET/early-PMF cohorts considering both every event separately and all together.In univariate analysis, male sex (p=0.003), previous thrombosis (p=0.001), splenomegaly (p=0.037), JAK2V617F (p=0.019) were associated with increased thrombotic risk; in multivariate Cox analysis, only previous thrombosis and male sex remained significant (p=0.012). Baseline splenomegaly was the only predictive factor for subsequent hemorrhages (p=0.017). Abnormal karyotype was associated with secondary MF (p=0.013) and also with second neoplasia (p<0.001). Together with JAK2V617F positivity and leukocytosis >11x109/L, abnormal karyotype was also associated with worse survival in univariate analysis. However, in multivariate analysis only JAK2V617F mutation remained as negative predictor of survival (p=0.019). Also, multivariable analysis confirmed JAK2 mutation and splenomegaly as independent risk factors for cumulative events.ConclusionsWith the limitations due to the low number of early-PMF, the outcome of young adults with early-PMF and true ET seemed to be comparable. The correlation of abnormal karyotype with MF transformation and second neoplasia suggests the need for an accurate cytogenetic analysis at diagnosis. Mutational status did influence disease phenotype, in terms of baseline characteristics and prognosis. Indeed, JAK2 mutational status confirmed a negative prognostic role for thrombosis and survival, while event-free survival was significantly better in triple-negative patients. Notably, causes of death were mostly related to the hematological malignancy, pointing out the substantial impact that this generally indolent disease may acquire in young adults. [Display omitted] DisclosuresLatagliata:Novartis: Consultancy; Bristol Myers-Squibb: Consultancy; Celgene: Consultancy; Shire: Consultancy. Cavo:Janssen: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; BMS: Consultancy, Honoraria; Millenium: Consultancy, Honoraria; Onyx: Honoraria.

Leukocyte Count Defines Patients on Risk for Thrombotic Complications with Well Controlled Essential Thrombocythemia- Data from a Patient- Registry

There is compelling evidence that white blood cell (WBC) counts impact the risk of thrombosis in patients with myeloproliferative neoplasms (MPN) (Barbui Blood 2013). Moreover, recent publications disclosed significant differences regarding certain disease characteristics and the course of disease in WHO 2008 (Tefferi Blood 2007) classified essential thrombocythemia (ET) and prefibrotic primary myelofibrosis (PMF) (Kvasnicka Am J Hematol 2008; Barbui JCO 2011; Buxhofer-Ausch Am J Hematol 2012). Hence, patients cohorts classified prior to WHO 2008 may likely consist of a mix of patients with ET and prefibrotic PMF.We aimed to reproduce the influence of WBC counts on the thrombotic risk in patients under real-life conditions. Therefore we assessed data of 825 Austrian patients from a patient registry for anagrelide in ET that was initiated 2001 in Austria due to an official authorities demand and is now being maintained in several Central European countries.Efficacy of treatment was assessed by investigating the course of platelet counts and event free survival relating to the first minor or major thrombotic event. WBC counts from the first available time points were correlated with the first thrombotic event. The cut off for the WBC subgroup analysis was set at 8,5 G/l. Statistical analysis was performed using the open-source R statistical software package, version 3.0.2. Non-parametric two-sided 95% confidence intervals for medians were calculated. Survival probabilities were assessed by applying the Kaplan-Meier method. For the comparison of time to event between the leukocyte- specific subgroups the log-rank test was used.Median Follow up of the study cohort is 3,07 years. Platelet count at start of anagrelide was median 777 G/l (95% CI 757-803). After 12, 24 and 36 months patients presented with median platelet counts of 473, 457 and 438 G/l, respectively. Median WBC count at start of therapy was 9 G/l (95% CI 8,7-9,3) and after 12, 24 and 36 months 8,5 G/l, 9,2 G/l and 8,7G/l, respectively. Incidence of thrombotic events per 100 patient- years was 5,14 for all events and 1,65 for major events only. 102 patients experienced at least one minor or major thrombotic event (major events n=36). Median time to the first minor or major thrombotic event was 1,27 years. Probability of event free survival at 1 year is 94,4% and at 3 years 87,6%. Patients with a baseline WBC count of higher than 8,5 G/l exhibit a significantly shorter probability of event free survival than patients below the cut off (p= 0,007 for all thrombotic events; p= 0,026 for major events only).This data proof the efficacy of anagrelide in lowering platelet counts and reducing significantly the risk of thrombotic events in patients with ET. The significantly shorter event free survival of patients with a WBC count above 8,5 G/l confirms earlier studies for the first time in a real-life setting. This result emphasizes the separation of true ET from prefibrotic PMF by using the WHO 2008 classification. Moreover, further investigations are needed to assess, whether a correlation of certain platelet and leukocyte counts modifies the risk of thrombotic events in MPN. DisclosuresSchloegl:AOP Orphan Pharmaceuticals AG: Research Funding.

Diagnosis according to World Health Organization determines the long-term prognosis in patients with myeloproliferative neoplasms treated with anagrelide: Results of a prospective long-term follow-up

ObjectivesDuring long term follow-up of a cohort of patients with essential thrombocythemia (ET) and polycythemia vera (PV) a higher than expected incidence of myelofibrosis (MF) was noted. In order to test if the explanation could be found in the diagnostic criteria a re-evaluation of diagnosis using the 2008 WHO diagnostic criteria for ET and MF was performed.MethodsThis prospective study of 60 patients with ET and PV was set up in 1998 to evaluate the long-term efficacy and tolerability of anagrelide treatment. Bone marrow trephine biopsies were requested from study start, after 2 and 7 years of follow-up. A blinded re-evaluation of the bone marrow trephines was performed. The 2008 WHO bone marrow criteria were used for diagnosis and fibrosis grading.ResultsOf 40 patients with an initial diagnosis of ET, 21 were confirmed as ‘true ET’ whereas 17 were reclassified as primary myelofibrosis (PMF) (12 PMF-0, 3 PMF-1, 2 PMF-2) and 2 as myeloproliferative neoplasms of uncertain origin. After 7 years of follow-up, 19 of 21 patients with ‘true ET’ were alive, none had transformed to MF, leukemia, or myelodysplastic syndrome. In contrast, 4/17 patients reclassified as PMF had died, two patients transformed to myelodysplastic syndrome and 7 patients progressed to overt MF.DiscussionWe conclude that a blinded re-evaluation of bone marrow trephines from study start and after 7 years of follow-up using 2008 World Health Organization criteria was able to differentiate between true ET and PMF with a marked difference in follow-up outcome.

Gene expression profiling with principal component analysis depicts the biological continuum from essential thrombocythemia over polycythemia vera to myelofibrosis

The recent discovery of the Janus activating kinase 2 V617F mutation in most patients with polycythemia vera (PV) and half of those with essential thrombocythemia (ET) and primary myelofibrosis (PMF) has favored the hypothesis of a biological continuum from ET over PV to PMF. We performed gene expression profiling of whole blood from control subjects (n = 21) and patients with ET (n = 19), PV (n = 41), and PMF (n = 9) using DNA microarrays. Applying an unsupervised method, principal component analysis, to search for patterns in the data, we demonstrated a separation of the four groups with biological relevant overlaps between the different entities. Moreover, the analysis separates Janus activating kinase 2-negative ET patients from Janus activating kinase 2-positive ET patients. Functional annotation analysis demonstrates that clusters of gene ontology terms related to inflammation, immune system, apoptosis, RNA metabolism, and secretory system were the most significantly deregulated terms in the three different disease groups. Our results yield further support for the hypothesis of a biological continuum originating from ET over PV to PMF. Functional analysis suggests an important implication of these gene ontology clusters in the pathogenesis of these neoplasms and in disease evolution from ET over PV to PMF.

Sensitivity and Specificity of Laboratory Parameters to Detect Early/Prefibrotic Myelofibrosis in 857 Patients with Essential Thrombocythemia. A Diagnostic Algorithm

Abstract 5148 INTRODUCTION.Patients presenting with a clinical picture of essential thrombocythemia (ET) can actually have an early/prefibrotic myelofibrosis (PMF), according to current WHO criteria, in about 18% of cases. Laboratory tests which are significantly different in early/prefibrotic PMF as compared with histologically confirmed ET (WHO-ET) include decreased gender-matched hemoglobin (Hb), increased white blood cell (WBC), platelet (PLT) counts and lactate dehydrogenase (LDH) values. AIM.To evaluate sensitivity (SE) and specificity (SP) of blood cell counts and LDH, at presentation, for the diagnosis of early/prefibrotic PMF vs. WHO-ET. METHODS.Five hundred thirty-six cases (50%) who had complete laboratory data measured at diagnosis constituted the exploratory set of our study and were derived from an international ET database. The discriminatory ability of Hb, WBC, PLT and LDH in correctly classifying patients in the early/prefibrotic PMF or WHO-ET groups was initially tested by plotting their Receiving Operating Characteristic (ROC) curves and comparing the relative Areas Under the Curve (AUC) with the value of 0.50 (which stands for the completely useless of the test). Three parameters with statistically significant discriminatory power were chosen (Hb, WBC and LDH) and thresholds searched in order to guarantee at least 90% of SE or SP. Finally, a diagnostic algorithm was designed.The validation set of this analysis was constituted by 321 patients with WHO-ET (n=62) or early/prefibrotic PMF (n=259) diagnosed by the same pathologist who confirmed the training set cohort and collected in the Institute for Pathology, University of Cologne, Germany. SE and SP for the same parameters and thresholds as well as the final diagnostic algorithm were applied to this set of patients to demonstrate the results' reproducibility. RESULTS.Sensitivity and specificity to recognize early/prefibrotic PFM have been evaluated by ROC curves. The best performance was found for LDH (AUC = 0.7059). WBC and Hb had super imposable curves, with AUC of 0.6279 and 0.6257, respectively. The worst performance was registered for PLT count: its AUC was only 0.5628, not significantly different from the reference value of 0.50 (p=0.154). Thresholds of Hb, WBC and LDH were searched to achieve at least 90% of SE or SP. HB < 12 g/dL for women or <13 g/dL for men, and WBC >= 13 x109/L had higher SP (92% and 91%, respectively). High SP is highly related to the presence of early/prefibrotic PMF (true positives).On the contrary, LDH < 200 mU/mL and WBC < 7 x109/L had good sensitivity (91% and 94%, respectively). High SE is highly related to the absence of early/prefibrotic PMF (true negatives). By applying these SE and SP values in a step-by-step algorithm, nearly half of patients (48%) could be classified as WHO-ET or early/prefibrotic PMF, assuming at each step a margin of error of less than 10%. For the remaining 50% of patients, laboratory results didn’t allow to suspect or exclude the presence of early/prefibrotic PMF.In the validation set of 321 patients classified by WHO 2008 as true ET or early/prefibrotic PMF (Cologne cohort) SP of anemia was 84%, WBC < 7 x109/L or >= 13 x109/L had 91% and 81% of SE and SP, respectively. LDH values < 200 mU/mL had 85% of SE. By applying the same flow-chart, 46% of patients were classified as WHO-ET or early/prefibrotic PMF. CONCLUSIONS.The present study provides clinicians with laboratory parameters that should increase suspicion of early/prefibrotic PMF in a patient with a working clinical diagnosis of ET. In fact, while patients presenting clinically with ET can now be discriminated as true ET or early/prefibrotic PMF by adopting the WHO 2008 criteria that require bone marrow histology, an algorithm including baseline anemia, WBC count and LDH, allows this differentiation in about 50% of patients with a good approximation. However, for a definitive proof, bone marrow histology is still an integral part for final diagnosis. Disclosures:Vannucchi:Novartis: Honoraria.

Essential thrombocythemia versus early primary myelofibrosis: a multicenter study to validate the WHO classification

AbstractControversy persists regarding the role of histopathology in the distinction between essential thrombocythemia (ET) and early-prefibrotic primary myelofi-brosis (PMF) presenting with thrombocythemia. To investigate the impact and reproducibility of bone marrow (BM) morphology according to the World Health Organization classification, 295 patients with the presumptive clinical diagnosis of either ET or early PMF were studied. Data of this cohort (Vienna group) were compared with 732 corresponding patients (Cologne group). Evaluating blindly (only age and gender known) BM specimens, the 2 groups of pathologists achieved an overall consensus of 78% regarding the total series and 88% concerning the discrimination between ET versus PMF. In 126 ET and 81 early PMF patients without pretreatment and complete documentation, a 90% concordance with the independently established clinical diagnosis was found. In 12 patients, overlapping of histopathology and some clinical findings between ET and polycythemia vera occurred. Contrasting ET, early PMF showed significant differences of presenting hematologic data and an unfavorable prognosis (estimated mean survival, 14 vs 21 years). Comparison of clinical and survival data of the Vienna cohort with the historical Cologne series revealed an overall congruence. This study highlights the impact of BM morphology for the differentiation between true vs false ET.

Survival and Risk of Leukemic transformation in Essential Thrombocythemia Are Significantly Influenced by Accurate Morphologic Diagnosis: An International Study on 1,104 Patients

AbstractAbstract 457 Introduction-The 2008 World Health Organization (WHO) diagnostic criteria for myeloproliferative neoplasms (MPN) underscore the role of bone marrow (BM) morphology in distinguishing essential thrombocythemia (ET) from early, and at times prefibrotic, primary myelofibrosis (PMF) that clinically presents like ET. The value of such a distinction in predicting clinical outcome has been questioned by some investigators. Study Design-Clinician scientists and hematopathologists from seven international centers of excellence for ET convened to design a clinicopathologic database of patients locally diagnosed and treated as ET. Study eligibility criteria included availability of treatment-naïve BM specimens obtained within one year of diagnosis. All bone marrows subsequently underwent a central blinded re-review by the author of the pertinent WHO chapter (JT) who applied strict WHO guidelines to identify cases of early PMF that were spuriously diagnosed as ET. Results-Revision of the BM biopsies according to the WHO morphological criteria confirmed ET in 891 patients (81%). Diagnosis was revised to early, prefibrotic PMF in 180 patients (16%). The remaining 33 (3%) BM specimens were qualitatively inadequate for accurate classification or represented unclassified cases.i) At presentation, early PMF, as opposed to true ET, was characterized by higher leukocyte (p<0.0001) and platelet (p=0.002) counts, lower hemoglobin (p=0.01) and hematocrit (p=0.001) levels, higher serum lactate dehydrogenase level (p<0.0001), higher circulating CD34+ cell count (p=0.03) and higher rate of palpable splenomegaly. JAK2V617F mutational frequency was 60% in each of the two groups.ii) Median follow-up was 6.2 years for ET and 7.0 years for early PMF. During this period, the rates of arterial (1.2-1.4% patients/year) and venous (0.6 patients/year) thrombotic complications were similar in the two groups. However, patients with early PMF, as compared to those with ET, were more likely to develop overt myelofibrosis (1% vs. 0.5% patients/year; RR=2.0, p=0.04) or acute leukemia (0.6% vs. 0.1% patients/year; RR=5.2, p=0.001). Cumulative leukemic transformation rate at 10 and 15 years was 0.7% and 2.1% in true ET versus 5.8% and 11.7% in PMF Similarly, survival was significantly worse in patients with early PMF (mortality rate: 2.7% vs. 1.3% patients/year; RR=2.1, p=0.002).The 10 and 15-years overall survival rates were: 89% and 80% in true ET versus 76% and 59% in PMF. On multivariable analysis, other risk factors for poor survival were age > 60 years (HR=6.3, p<0.0001), a leukocyte count of > 11×109/L (HR=2.13, p<0.0001) and history of thrombosis (HR=3.0, p<0.0001). Conclusions-The current study validates the clinical relevance of strict adherence to WHO criteria in the diagnosis of ET and provides seminal information on the survival and risk of leukemic transformation in strictly WHO-defined ET, which appears to be substantially better than previously assumed. Disclosures:No relevant conflicts of interest to declare.

Bone Marrow Biopsy Revision According to WHO Criteria in 272 Patients of the Registro Italiano Trombocitemia (RIT): Preliminary Report On Clinical and Histopathological Implications.

Abstract 4974 BackgroundThe bone marrow trephine biopsy (BMB) has a crucial role for the diagnosis of essential thrombocythemia (ET), both according to the PVSG and the WHO criteria. The WHO 2001 criteria enhanced the role of BMB also by distinguishing the true-ET (ET) from the prefibrotic and the early fibrotic chronic idiopathic myelofibrosis. The WHO 2008 criteria, in the JAK2 era, confirmed the diagnostic and prognostic relevance of the histopathological features in ET as well as in the other Ph-neg myeloproliferative neoplasms (MPN). Otherwise, only few validated data are presently available, and the reproducibility in the evaluation of some morphological details is still controversy. ObjectiveTo validate ET diagnosis in a large registry-based series of patients by revising the BMB specimens according to the WHO criteria and to evaluate the potential relationship between the histopathological and the clinical parameters at presentation. MethodsThe hematological centers of the Registro Italiano Trombocitemia (RIT) were invited to participate to this study by sending the BMB specimens (hematoxylin-eosin, Giemsa and silver stains) obtained at diagnosis. The clinic-pathological panel of the RIT (with three hematopathologists as permanent members coordinated by a chairman) performed a centralized revision of the BMB specimens, concomitantly (multiheaded microscopy) and blindly (only patient sex and age were known). The panel described for each case the morphological features and gave a diagnostic conclusion according to WHO criteria as follows: true-ET (ET); or initial primary myelofibrosis (i-PMF) distinguished in prefibrotic PMF (pf-PMF/MF-0) and early fibrotic PMF (ef-PMF/MF-1); or advanced PMF (MF-2 and MF-3); or early polycythemia vera (e-PV); or MPN unclassifiable (MPN-U); or diagnosis other than MPN (No MPN). ResultsThirteen centers sent the specimen of BMB at diagnosis of 272 patients registered into the RIT and diagnosed in the years 1986-2002 (group A, cases 66, 24.3%), 2003-2005 (group B, cases 95, 34.9%) and 2006-2008 (group C, cases 111, 40.8%). The patients, 104 (38%) males and 168 (62%) females, had at diagnosis: age over 50 in 64% of cases (median 58); PLT count (109/L) >1000 in16% and <= 600 in 24% of cases (median 789); Hgb level (g/dL) >17 in 1% and <=9 in 5% of cases (median 14.3); WBC count (109/L) >9 in 44% of cases (median 8.6); splenomegaly in 18% of cases. Disease symptoms, thrombotic and hemorrhagic events were reported in 40%, 21%, and 7% of cases, respectively.During the follow-up (median 2.7 years) 65% of patients received cytoreductive drugs (Hydroxyurea 59%, Anagrelide 20%, Interferon 14%, Pipobroman 6.5%, Busulfan 0.5%).The revision of the 272 BMB specimens allowed to the following diagnosis: ET 142 cases, 52.2%; i-PMF 72 cases, 26.5% (distinguished in pf-PMF 19 cases, 7% and ef-PMF 53 cases, 19.5%); e-PV 13 cases, 4.8%; MPN-U 16 cases, 14.3%; No MPN 8 cases, 2.9%. In the patients of groups A, B, and C the rate of ET was increasing (from 44%, to 50% and to 59%, respectively) while the rate of i-PMF was decreasing (from 34%, to 31% and to 18%, respectively); moreover, the rate of e-PV was 0%, 6%, and 6%, respectively.The ET patients compared with the i-PMF patients showed at diagnosis a lower rate of splenomegaly (16/142, 11.3% vs 24/72, 33.3%, p<0.0001), of age >50 years ( 84/142, 59.2% vs 53/72, 73.6%, p<0.03), and a higher rate of PLT count (109/L) <=600 (39/142, 27.5% vs 11/72, 15,3%, p<0.04 ); no significant differences were found between the two groups for sex, Hgb level, WBC count, symptoms, thrombotic and hemorrhagic events. The treatment rate was lower in ET than in i-PMF (ratio 0.7). ConclusionThis preliminary report on the revision of the BMB at diagnosis in 272 patients of the Registro Italiano Trombocitemia (RIT) shows that: the rate of true ET is continously increasing (from 44% before 2003 to 59% in the period 2006-2008), with i-PMF rate concomitantly decreasing (from 34% to 18%); the ET patients, compared with the i-PMF ones, were younger, with lower PLT count and with lower rate of splenomegaly, and received a less intensive cytoreductive treatment. DisclosuresNo relevant conflicts of interest to declare.

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.

Bone marrow pathology in essential thrombocythemia: interobserver reliability and utility for identifying disease subtypes

The role of histopathology in the diagnosis of essential thrombocythemia (ET) is controversial, and there has been little attempt to quantitate interobserver variability. Diagnostic bone marrow trephine biopsy specimens from 370 patients with ET by Polycythemia Vera Study Group (PVSG) criteria were assessed by 3 experienced hematopathologists for 16 different morphologic features and overall diagnosis according to the World Health Organization (WHO) classification. Our results show substantial interobserver variability, particularly for overall diagnosis and individual cellular characteristics such as megakaryocyte morphology. Reticulin grade was the dominant independent predictor of WHO diagnostic category for all 3 hematopathologists. Factor analysis identified 3 independent factors likely to reflect underlying biologic processes. One factor related to overall and lineage-specific cellularity and was significantly associated with JAK2 V617F status (P < .001), a second factor related to megakaryocyte clustering, and a third was associated with the fibrotic process. No differences could be discerned between patients labeled as having "prefibrotic myelofibrosis" or "true ET" in clinical and laboratory features at presentation, JAK2 status, survival, thrombosis, major hemorrhage, or myelofibrotic transformation. These results show that histologic criteria described in the WHO classification are difficult to apply reproducibly and question the validity of distinguishing true ET from prefibrotic myelofibrosis on the basis of subjective morphologic criteria. This study was registered at http://isrctn.org as #72251782 and at http://eudract.emea.europa.eu/ as #2004-000245-38.

Prefibrotic myelofibrosis: is this diagnosis valid?

Wilkins and colleagues evaluate the utility of the World Health Organization (WHO) diagnostic criteria intended to separate cases previously classified as essential thrombocythemia (ET) into 2 groups: “true ET” and “prefibrotic myelofibrosis.” Focusing on bone marrow histology, the authors found substantial variation in classification of cases.

JAK2V617F positive early stage myeloproliferative disease (essential thrombocythemia) as the cause of portal vein thrombosis in two middle-aged women: therapeutic implications in view of the literature

The present study describes portal vein thrombosis (PVT) in two women as the first and single presenting symptom of latent or masked myeloproliferative disease (MPD). Essential thrombocythemia (ET) was suspected by a sustained increase in platelet count (>400 x 10(9)/l) and slight splenomegaly on echogram. ET could be diagnosed by the presence of large platelet in peripheral blood smear, an increase in clustered large megakaryocytes in bone marrow smear and the presence of the JAK2(V617F) mutation. A subsequent biopsy specimen was consistent with the diagnosis of true ET. In patients with a first episode of splanchnic vein thrombosis (SVT), analysis of any venous thrombophilic risk factors as well as a JAK2(V617F) mutation status indicative for MPD is warranted. Administration of heparin followed by oral anticoagulation with vitamin K antagonists is the treatment of choice in patients with SVT. Anticoagulation therapy combined with low-dose aspirin and proper treatment of the MPD is recommended in patients with SVT associated with the JAK2(V617F) mutation.

WHO bone marrow features and European clinical, molecular, and pathological (ECMP) criteria for the diagnosis of myeloproliferative disorders

The bone marrow criteria defined by the World Health Organization (WHO) are based on characteristic increase and clustering of morphologically abnormal enlarged megakaryocytes as a pathognomonic clue to describe three distinct phenotypic entities of myeloproliferative disorders (MPDs): (1) essential thrombocythemia (ET), (2) early and overt polycythemia vera (PV) and (3) prefibrotic, early fibrotic, and fibrotic chronic idiopathic myelofibrosis (CIMF-0, 1, 2 and 3). Based on established WHO bone marrow features, and the use of new molecular and laboratory markers including JAK2 V617F mutation, endogenous erythroid colony (EEC) formation and serum erythropoietin (EPO), we present updated European clinical, molecular and pathological (ECMP) criteria for the differential diagnosis of true ET, PV and CIMF. As compared to the WHO bone marrow features, each of the laboratory and molecular markers are not sensitive enough for the diagnosis and classification of the three prefibrotic MPDs. The proposed WHO/ECMP criteria reduce the platelet count to the upper limit of normal (>400 × 10 9 l −1) as inclusion criterion for the diagnosis of thrombocythemia in true ET, early stages of PV and prefibrotic CIMF. The combined use of WHO and ECMP criteria differentiate PV from congenital and acquired erythrocytosis, true ET from reactive thrombocytosis and separates true ET from CIMF-0/1 mimicking ET. Only half of the patients with true ET and CIMF carry the JAK2 V617F mutation (sensitivity 50%). Early PV mimicking ET is featured by the presence of JAK2 V617F mutation, EEC, low serum EPO levels, normal hematocrit, and increased bone marrow cellularity due to increased erythropoiesis (“forme fruste” PV) when WHO/ECMP criteria are applied. The combination of JAK2 V617F PCR test and increased hematocrit is diagnostic for PV (sensitivity 95%, specificity 100%). The degree of JAK2 V617F positivity of granulocytes is related to disease stage: heterozygous in true ET and early PV and mixed hetero/homozygous to homozygous in overt and advanced PV and CIMF. Bone marrow histology assessment should remain the gold standard criterion for the diagnosis and staging of the MPDs true ET, PV and CIMF and its differentiation from primary or secondary erythrocytosis, reactive thrombocytosis and thrombocythemias associated with atypical MPD, myelodysplastic syndromes, and chronic myeloid leukemia,. The proposed WHO/ECMP criteria allow a cross talk between clinicians, pathologists and scientists to much better characterize the nature and natural history of each of the WHO/CMP defined early and overt MPDs.

The Registro Italiano Trombocitemie (GIMEMA Project): Preliminary Analysis of the First 801 Enrolled Patients.

Epidemiological, diagnostic, prognostic and therapeutical data were retrospectively obtained by the Italian Registry in over 2000 Essential Thrombocythemia (ET) patients who mainly were diagnosed according to the PVSG criteria and were treated with potentially leukemogenic drugs. The Registro Italiano Trombocitemie (RIT), that is a GIMEMA project, has been activated in order to registry italian ET patients, to improve the diagnosis appropriateness (WHO criteria), to promote the acquisition of biological data, to evaluate the compliance to the therapeutical guidelines of the Italian Society of Hematology (SIE), to monitor in particular the ET patients receiving Interferons alpha and Anagrelide, to evaluate cases of pregnancy, pediatric age and familiarity, to define the prognostic value of the biological factors as JAK2 mutation, clonality, etc, to create a network for activation of new clinical and biological studies. The RIT, co-ordinated by the Hematology Unit of Reggio Emilia, is a web based registry that beside a public area comprehends a database of italian ET patients. The data, with respect of the privacy rules, are object of validation and analysis by various RIT expert subcommittees. Eighty hematological Institutions adhered to the RIT and 801 patients have been registered since June 2005. The ET diagnosis was done according to the PVSG (90%) and WHO (10%) criteria. The patients, 492 females and 309 males, had age <40 yr (19%), 40–60 yr (32%), 60–70 yr (19%), >70 yr (30%), and the median age was 59 years. At diagnosis the platelet count was >1000 ×109/L in 29% of cases (mean 932). Few patients had prior thrombosis (4%; major 2%) and prior hemorrhage (2.6%). Patients at high risk of thrombosis were 55% on considering age >60 yr and/or previous thrombosis and/or PLT count >1500 ×109/L, and 65% on considering the PLT count cut-off of 1000 ×109/L. The patients shown general thrombotic risk factors (70%), disease related symptoms (40%) and splenomegaly (25%). By applying the WHO diagnostic criteria, the picture of true ET was found in 27% of cases. Sixty pregnancies have been reported. Aspirin was administered in 72% of patients and cytoreduction was performed in 62% of them, with use of Hydroxyurea (65%), Anagrelide (10%), Interferons alpha (10%), Pipobroman (4%), Busulfan (2%). A separate analysis for patients treated with Anagrelide and Iterferons alpha is in progress. To improve the diagnostic approach, the RIT has promoted the bone marrow biopsy revision (WHO criteria) and the acquisition of the new biological parameters.