Nonvitamin K Antagonist Oral Anticoagulant in Patients With Venous Thromboembolism and Polycythemia Vera or Essential Thrombocythemia: A Cohort Study

ABSTRACT

Thrombosis is the most common adverse event in patients with polycythemia vera (PV) and essential thrombocythemia (ET). Little is known about the use of nonvitamin K antagonist oral anticoagulants (NOACs) in patients with myeloproliferative neoplasms. We sought to evaluate the efficacy and safety of NOAC in a cohort of patients with PV and ET, who experienced venous thromboembolism (VTE). We enrolled 48 consecutive patients with PV (70.8%) and ET [median age 67.0 (interquartile range, 58.5-72.0) years], who experienced VTE. Patients received apixaban (39.6%), rivaroxaban (33.3%), or dabigatran (27.1%). During a median follow-up of 30 (interquartile range, 20.5-41.5) months, recurrent thrombotic events and bleeding were recorded. Four thrombotic events (3.3 per 100 patient-years) were reported. Three deep vein thrombosis episodes (2.5 per 100 patient-years) were experienced by 2 patients with PV, who received apixaban (5 mg bid) and dabigatran (150 mg bid), and 1 patient with ET, who received dabigatran (150 mg bid). One ischemic stroke occurred in a patient with PV on rivaroxaban (20 mg/d). There was 1 major bleeding (0.8 per 100 patient-years) in a patient with ET on dabigatran (150 mg bid) and 3 clinically relevant nonmajor bleeding (2.5 per 100 patient-years): 2 on rivaroxaban (20 mg/d) and 1 on apixaban (5 mg bid). We did not observe significant differences related to the type of NOAC. Three deaths (2.5 per 100 patient-years) unrelated to either VTE or bleeding were recorded. This study shows that NOACs may be effective and safe as secondary prevention of VTE in patients with myeloproliferative neoplasms.

Clinical and Prognostic Features of Essential Thrombocythemia: Comparison of 2001 WHO Versus 2008/2016 WHO Criteria in a Large Single-center Cohort

BACKGROUND

According to 2008/2016 classification of the World Health Organization (WHO), a platelet (PLT) count ≥ 450 × 10⁹/L, reduced from the previously published WHO 2001 indicated level ≥ 600 × 10⁹/L, was considered the new PLT threshold for the diagnosis of essential thrombocythemia (ET).

PATIENTS AND METHODS

To validate this important diagnostic change in a setting of current clinical practice, we retrospectively analyzed clinical and hematologic features at diagnosis and during follow-up of 162 patients with ET, diagnosed in our center from January 2008 to December 2017. We subdivided patients according to PLT value at baseline into Group A (PLT ≥ 600 × 10⁹/L) (124 patients; 76.5%) and Group B (PLT ≥ 450 × 10⁹/L < 600 × 10⁹/L) (38 patients; 23.5%).

RESULTS

Among clinical features, only the median value of leukocytes (P < .001) was significantly higher in Group A. Cytostatic treatment was administered in 103 patients, with a significantly higher rate in patients of group A (P < .001). After a median follow-up of 42.4 months (interquartile range, 22.1-70.6 months), 8 thrombotic events were recorded in the entire cohort, without differences between the 2 groups (P = .336). The 5-year overall survival (OS) of the entire cohort was 96.9% (95% confidence interval, 92.6%-100%), without differences between the 2 groups (P = .255).

CONCLUSIONS

Our data indicate a substantial homogeneity among patients with ET regardless of the PLT count at diagnosis, thus confirming the usefulness of the 2008/2016 WHO diagnostic criteria.

Cardiovascular Safety of Anagrelide Hydrochloride versus Hydroxyurea in Essential Thrombocythaemia

Essential thrombocythaemia (ET) is a rare myeloproliferative neoplasm. This multicentre, Phase 3b, randomised, open-label, non-inferiority study investigated the cardiac safety, efficacy and tolerability of first-line treatment with anagrelide or hydroxyurea in high-risk ET patients for up to 3 years. Eligible patients aged ≥ 18 years with a diagnosis of high-risk ET confirmed by bone marrow biopsy within 6 months of randomisation received anagrelide (n = 75) or hydroxyurea (n = 74), administered twice daily. Treatment dose for either compound was titrated to the lowest dose needed to achieve a response. Planned primary outcome measures were change in left ventricular ejection fraction from baseline over time and platelet count at Month 6. Planned secondary outcome measures were platelet count change from baseline at Months 3 and 36; percentage of patients with complete or partial response; time to complete or partial response; number of patients with thrombohaemorrhagic events; and changes in white blood cell count or red blood cell count over time. Neither treatment altered cardiac function. There were no significant differences in adverse events between treatment groups, and no reports of malignant transformation. The incidence of disease-related thrombotic or haemorrhagic events was numerically higher in anagrelide-treated patients. Both treatments controlled platelet counts at 6 months, with the majority of patients experiencing complete or partial responses. In conclusion, these results suggest that long-term treatment with anagrelide is not associated with adverse effects on cardiac function. This is one of the few studies using left ventricular ejection fraction assessment and central biopsy reading to confirm the diagnosis of ET.

Trial registration number: Clinicaltrials.gov NCT00202644

A randomized double-blind trial of 3 aspirin regimens to optimize antiplatelet therapy in essential thrombocythemia

Essential thrombocythemia (ET) is characterized by abnormal megakaryopoiesis and enhanced thrombotic risk. Once-daily low-dose aspirin is the recommended antithrombotic regimen, but accelerated platelet generation may reduce the duration of platelet cyclooxygenase-1 (COX-1) inhibition. We performed a multicenter double-blind trial to investigate the efficacy of 3 aspirin regimens in optimizing platelet COX-1 inhibition while preserving COX-2-dependent vascular thromboresistance. Patients on chronic once-daily low-dose aspirin (n = 245) were randomized (1:1:1) to receive 100 mg of aspirin 1, 2, or 3 times daily for 2 weeks. Serum thromboxane B2 (sTXB2), a validated biomarker of platelet COX-1 activity, and urinary prostacyclin metabolite (PGIM) excretion were measured at randomization and after 2 weeks, as primary surrogate end points of efficacy and safety, respectively. Urinary TX metabolite (TXM) excretion, gastrointestinal tolerance, and ET-related symptoms were also investigated. Evaluable patients assigned to the twice-daily and thrice-daily regimens showed substantially reduced interindividual variability and lower median (interquartile range) values for sTXB2 (ng/mL) compared with the once-daily arm: 4 (2.1-6.7; n = 79), 2.5 (1.4-5.65, n = 79), and 19.3 (9.7-40; n = 85), respectively. Urinary PGIM was comparable in the 3 arms. Urinary TXM was reduced by 35% in both experimental arms. Patients in the thrice-daily arm reported a higher abdominal discomfort score. In conclusion, the currently recommended aspirin regimen of 75 to 100 once daily for cardiovascular prophylaxis appears to be largely inadequate in reducing platelet activation in the vast majority of patients with ET. The antiplatelet response to low-dose aspirin can be markedly improved by shortening the dosing interval to 12 hours, with no improvement with further reductions (EudraCT 2016-002885-30).

The poor outcome in high molecular risk, hydroxycarbamide-resistant/intolerant ET is not ameliorated by ruxolitinib

Essential Thrombocythemia (ET) patients at high-risk of thrombosis require cytoreductive treatment, typically with hydroxycarbamide. Many patients are resistant or intolerant to hydroxycarbamide (HC-RES/INT) and are at increased risk of disease progression. MAJIC-ET is a randomized phase 2 study comparing ruxolitinib (RUX) to best available therapy (BAT) in HC-RES/INT ET, which showed no difference between the two arms in rates of hematological response or disease progression. The impact of additional non-MPN driver mutations (NDM) on the risk of disease complications in HC-RES/INT ET patients is unknown. Since the presence of NDM may influence trial outcomes, we expand the primary MAJIC-ET analysis to serially evaluate NDM in MAJIC-ET patients using a targeted myeloid 32-gene panel. NDM at baseline were detected in 30% of patients, most frequently affecting TET2 (11%) followed by TP53 (6.4%) and SF3B1 (6.4%). The presence of a NDM was associated with inferior 4-year transformation-free survival (TFS; 65.4% [95% CI 53.3 – 75%] vs. 82.8% [95% CI 73.2 – 89.1%], p=0.017). Specifically, TP53 (p=0.01) and splicing factor (SF, SF3B1, ZRSR2, SRSF2 ; p<0.001), but not TET2 mutations were associated with reduced TFS which was not mitigated by RUX treatment. Longitudinal analysis identified new mutations in 19.3% of patients; primarily affecting TET2, TP53 and SF3B1 . We report the first comprehensive mutational analysis of HC-RES/INT ET patients and highlight the clinical/prognostic utility of serial mutation analysis for NDM in HC-RES/INT ET, including the importance of SF and TP53 mutations which identify HC-RES/INT ET patients at increased risk of disease transformation.

JAK2 V617F-positive essential thrombocythemia with subsequent development of immune thrombocytopenia: A case report

RATIONALE

Although essential thrombocythemia (ET) and immune thrombocytopenia (ITP) have different etiologies, 3 previous reports have described ET development in ITP patients, all of whom were positive for the JAK2 V617F mutation. Here, we report the first published case of ITP following ET in the absence of other platelet disorders.

PATIENT CONCERNS

A 70-year-old woman with a five-year history of ET with JAK2 V617F mutation treated with hydroxycarbamide for five months presented with petechiae on her limbs.

DIAGNOSIS

Her platelet count was 3 × 10/L, with the immature platelet fraction being 29%. White blood cell count and hemoglobin level were normal. Bone marrow examination showed increased number of megakaryocytes, but no morphologic dysplasia in any lineage. G-band analysis revealed no abnormalities. Platelet transfusion and cessation of hydroxycarbamide did not affect the platelet count. Thrombocytopenia was unlikely to have been induced by drugs, heparin, systemic lupus erythematosus, or human immunodeficiency virus. Hence, a diagnosis of ITP was made.

INTERVENTIONS

The patient received oral prednisolone combined with intravenous immunoglobulin.

OUTCOMES

Her platelet count rose to 310 × 10/L and remained stable, while her steroid dose was reduced. Further blood tests revealed the presence of antibodies against Helicobacter pylori, and appropriate treatment was administered. Resumption of hydroxycarbamide did not induce thrombocytopenia.

LESSONS

Although ET and ITP have different etiologies, chronic inflammation and immune deregulation underlie both and may play an important role in the progression from one to the other. Further research is warranted to understand the relationship between ET and ITP.

Aquagenic pruritus in essential thrombocythemia is associated with a higher risk of thrombosis

BACKGROUND

Thromboses and phenotypic evolutions (leukemia, myelofibrosis) are the most frequent complications in polycythemia vera (PV) and essential thrombocythemia (ET). Aquagenic pruritus (AP) is not only PV symptom, but is also present in ET. The presence of pruritus in PV is associated with a lower risk of arterial thrombosis.

AIMS

To date, no equivalent study has been done to analyse the impact of AP for ET patients.

MATERIALS & METHODS

We used the data from our cohort of patients with myeloproliferative neoplasms seen in our institution (OBENE database, NCT02897297). We collect information at diagnosis, presence or not of AP and all types of complications during their follow-up. To avoid masked PV, all JAK2 positive cases were tested isotopic red mass cell if appropriate.

RESULTS

Among 396 ET patients, presence of AP was found in 42 (10.6%). ET patients with AP were more proliferative, more symptomatic at diagnosis and more difficult to treat. Furthermore, they presented increased risk of thromboses (30.9 versus 17%, P = .03; OR = 2.2 [1.01;4.66]) and phenotypic evolutions (33.3 versus 13.3%, P = .0007; OR = 3.2 [1.44;6.77]), during follow-up.

DISCUSSION

Aquagenic pruritus is classically associated to PV. But we confirmed here that AP is also present in ET and characterizes patients with higher risk of morbidity (thrombotic events and phenotypic evolutions).

CONCLUSIONS

The systematic determination of the presence of AP in ET patients should permit us to better identify these high-risk patients for better management and follow-up.

Mean Platelet Volume and Platelet Distribution Width Indicate that Platelets Remain Small for Most of Their Lifespans in Patients with Essential Thrombocythemia

BACKGROUND

Platelets are large when young and immature and shrink as they age. The mean platelet volume (MPV) and platelet distribution width (PDW) reflect the volume and distribution of platelets, respectively. We compared the MPVs and PDWs of patients with immune thrombocytopenic purpura (ITP) or essential thrombocythemia (ET) to those of healthy individuals to test whether these values can reflect the pathomechanisms of these diseases.

METHODS

Platelet counts, MPVs, and PDWs were measured in 153 healthy individuals and in 20 and 34 patients with ITP and ET, respectively, using an XN-3000 instrument.

RESULTS

The MPVs and PDWs were significantly higher in ITP patients than in healthy individuals or ET patients. The MPVs were significantly lower in ET patients than in both ITP patients and healthy individuals; however, the PDWs in ET patients were similar to those in healthy individuals. The MPVs and PDWs did not correlate with platelet count in ITP or ET patients.

CONCLUSIONS

Our data suggested an increased production of young, large platelets and nondiscriminatory destruction of circulating platelets irrespective of their ages in ITP. Decreased MPVs and unelevated PDWs in ET suggest that clonal process-produced platelets remain small throughout their lifespans.

Activation of TF-Dependent Blood Coagulation Pathway and VEGF-A in Patients with Essential Thrombocythemia

Background and objectives: Recent studies suggest that a vascular endothelial growth factor (VEGF-A) may be involved in the thrombotic process by stimulating the expression of tissue factor in vascular endothelial cells. Tissue factor (TF) can also stimulate the transcription of the gene encoding VEGF-A. The relationship between coagulation and angiogenesis in myeloproliferative neoplasms is not fully understood. The aim of this study was to evaluate the concentration of TF in relation to VEGF-A in the blood of patients with essential thrombocythemia (ET). Patients and methods: The study group consisted of 130, newly diagnosed patients with ET (mean age 61 years). The control group consisted of 35 healthy volunteers (mean age 51 years). Concentrations of VEGF-A, TF, and tissue factor pathway inhibitor (TFPI) were analysed using immunoenzymatic methods. TF and TFPI activities were performed using chromogenic assays. Results: The median concentration of TF Ag was 3-fold higher and the TF activity was more than 15-fold higher in ET patients than in normal individuals. There were no statistically significant differences in the TFPI concentration and activity between groups. VEGF-A was significantly increased in patients with ET (p < 0.000001). Analysis of correlations revealed a positive correlation between VEGF-A and TF Ag as well as a positive correlation between VEGF-A and TFPI activity. Conclusions: The simultaneous increase of TF concentration and activity, VEGF-A in the blood of patients with ET, as well as a positive correlation between the concentration of TF and VEGF-A demonstrates the coexistence of TF-dependent coagulation and activation of angiogenesis.

The role of hepcidin, GDF15, and mitoferrin-1 in iron metabolism of polycythemia vera and essential thrombocytosis patients

Background/aim

GDF15, hepcidin and mitoferrin-1 (mfrn-1) are proteins involved in systemic iron regulation. There are no studies in the literature demonstrating the serum mfrn-1 levels in polycythemia vera (PV) and essential thrombocythemia (ET) patients. The aim of this study was to investigate GDF15, hepcidin and mfrn-1 levels in PV and ET patients.

Materials and methods

Ten PV, 17 ET patients, and 27 healthy controls (HCs) were enrolled. GDF15, hepcidin and mfrn-1 values were measured with enzyme-linked immunosorbent assay (ELISA).

Results

GDF15 levels were higher in the myeloproliferative neoplasm (MPN) group (P = 0.002). Hepcidin levels were not different between MPN patients and HCs. The mfrn-1 levels were lower in MPN patients (P = 0.039). Hepcidin, GDF15, and mfrn-1 levels were not different between PV and ET patients. mfrn-1 levels were lower in ET patients than HCs (P = 0.038).

Conclusion

Increased erythropoiesis in MPNs may lead to high GDF15 levels in these patients. However, hepcidin was not suppressed despite the increased GDF15 levels and erythropoiesis in these patients. Decrease in mfrn-1 in MPNs can be the result of its increased turnover due to increased myelopoiesis. It can be hypothesized that similar hepcidin levels in patients and controls and low mfrn-1 levels in patients may be a defense mechanism against erythroid activity and thromboembolic complications.

Study on the Clinical Significance of JAK2V617F Allele Burden in Philadelphia Chromosome-Negative Myeloproliferative Neoplasm

BACKGROUND

It was discovered that the somatic mutation in JAK2 exon 14 (JAK2V617F) totally modified the understanding and diagnosis of Philadelphia-Negative myeloproliferative neoplasm (Ph-MPNs), including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). Real-time quantitative PCR is the most widely used method for JAK2V617F detection in clinical laboratory. In this study, we aimed to evaluate the clinical significance of JAK2V617F allele burden in Ph-MPNs detected by real-time quantitative PCR.

METHODS

A total of 208 bone marrow samples were collected from patients suspected to have Ph-MPNs. Real-time quantitative PCR was performed on each sample to obtain the JAK2V617F allele burden. Clinical and laboratory data from these participants were also recorded for their first visit.

RESULTS

Out of 208 participants, 118 patients were confirmed with Ph-MPNs. JAK2V617F mutations were found in 59 patients in the PV group (86.8%), 31 patients in the ET group (70.5%). PV, PMF, and ET showed a significant difference in the distribution of JAK2V617F allele burden. In JAK2V617F positive patients, JAK2V617F allele burden was closely related with WBC counts, platelet counts, and hemoglobin concentration.

CONCLUSIONS

JAK2V617F allele burden is a useful marker in the diagnosis, discrimination, and evaluation of PhMPNs.

European LeukemiaNet study on the reproducibility of bone marrow features in masked polycythemia vera and differentiation from essential thrombocythemia

The purpose of the study was to assess consensus and interobserver agreement among an international panel of six hematopathologists regarding characterization and reproducibility of bone marrow (BM) histologic features used to diagnose early stage myeloproliferative neoplasms, in particular differentiation of so-called masked/prodromal polycythemia vera (mPV) from JAK2-mutated essential thrombocythemia (ET). The six members of the hematopathology panel evaluated 98 BM specimens independently and in a blinded fashion without knowledge of clinical data. The specimens included 48 cases of mPV according to the originally published hemoglobin threshold values for this entity (male: 16.0-18.4 g/dL, female: 15.0-16.4 g/dL), 31 cases with overt PV according to the updated 2016 WHO criteria, and 19 control cases. The latter group included cases of JAK2-mutated ET, primary myelofibrosis, myelodysplastic syndrome, and various reactive conditions. Inter-rater agreement between the panelists was very high (overall agreement 92.6%, kappa 0.812), particularly with respect to separating mPV from ET. Virtually all cases of mPV were correctly classified as PV according to their BM morphology. In conclusion, a central blinded review of histology slides by six hematopathologists demonstrated that highly reproducible specific histological pattern characterize PV and confirmed the notion that there are no significant differences between mPV and overt PV in relation to BM morphology.

The role of certain gene polymorphisms involved in the apoptotic pathways in polycythemia vera and essential thrombocytosis

BACKGROUND

Polycythemia vera (PV) and essential thrombocytosis (ET) are hematological disorders characterized by excessive production of mature and functional blood cells. These cellular disorders are thought to be associated with impaired apoptosis, which is one of the major cellular death mechanisms in hematopoietic cells.

OBJECTIVES

In this study, our objective was to examine the association between potential polymorphisms of the Bcl 2, Bax, Fas and Fas Ligand genes involved in apoptosis and the occurrence of PV and ET.

MATERIAL AND METHODS

A total of 93 patients diagnosed with PV (n = 38) or ET (n = 55) at the Department of Hematology were included in this study, and 93 healthy individuals served as controls. DNA isolation was performed in blood samples obtained from both groups of subjects to determine the Bcl 2, Bax, Fas, and Fas L genotypes using the real-time PCR method.

RESULTS

No statistically significant differences between controls and patients were found in terms of Fas -670 G > A (rs1800682), Fas -1377 G > A (rs2234767), Fas L IVS2 -124 A > G (rs5030772), Bax -248 G > A (rs4645878) and Bcl 2 -938 C > A (rs2279115) polymorphisms, genotypes, and allele frequency (p > 0.05).

CONCLUSIONS

The results show that polymorphisms in the Bcl 2, Bax, Fas, and Fas Ligand genes involved in the apoptotic pathways may not play a role in the pathogenesis of PV and ET.

γ-Glutamyl Transferase Is an Independent Biomarker of Splanchnic Thrombosis in Patients With Myeloproliferative Neoplasm

Myeloproliferative neoplasms (MPNs) are associated with an increased risk of thrombotic events and constitute the major risk factor of splanchnic venous thrombosis (SVT) in Western countries. Although timely anticoagulation resolves SVT, unrecognized SVT frequently leads to portal hypertension and, potentially, variceal bleeding, which may render anticoagulation difficult. Thus, early identification of SVT development is clinically relevant in MPN patients.In this retrospective analysis, we included 126 patients with MPN and/or SVT referred to our hospital between 2009 and 2014. A total of 86 patients diagnosed with MPN formed the first cohort (PV n = 18, ET n = 16, and MF n = 40), whereas 40 patients who had SVT without adjunct MPN formed a control cohort. Median follow-up period was 960 days. Clinical and laboratory data were collected and analyzed for the identification of potential biomarkers applying descriptive statistics, nonparametric testing, Kaplan-Meier, and logistic regression analysis. The relevance of the identified biomarkers was evaluated in an independent 2nd cohort of 181 patients from the MPN registry of the Study Alliance of Leukemia (SAL-MPN).Thirty-three MPN patients (38%) in the 1st cohort had SVT. Elevated levels of aspartate aminotransferase, alanine aminotransferase, serum bilirubin, or γ-GT were significantly correlated to the presence of SVT. In multivariate testing, CRP and aspartate aminotransferase were predictors for survival and γ-GT remained the only significant variable associated with SVT in MPN patients (P < 0.05). These findings were confirmed in the 2nd cohort comprising 42% of patients with MPN suffering from SVT.Elevated γ-GT levels indicate SVT in MPN patients, whereas CRP levels are independent predictors of patient survival.

Qualitative and quantitative modifications of von Willebrand factor in patients with essential thrombocythemia and controlled platelet count

BACKGROUND

Essential thrombocythemia (ET) is characterized by increased platelets and prevalent thrombosis. An acquired von Willebrand factor (VWF) disease has been hypothesized and inconsistently associated with extreme thrombocytosis or rare bleeding in ET. Whether VWF is modified in ET patients with controlled platelet count remains unclear.

OBJECTIVES

We studied different VWF- and platelet-associated parameters in ET patients treated according to current recommendations.

PATIENTS/METHODS

Sixty-nine ET patients (M = 29; median age, 62 [48-70] years; platelets, 432 [337-620] × 10(3)  μL(-1) ), 69 matched controls and 10 subjects with reactive thrombocytosis (RT) were studied. VWF:antigen (Ag), activity (act), electrophoretic patterns, VWF:propeptide, plasma glycocalycin (GC), glycoproteinV (GpV), ADAMTS-13, elastase, C-reactive protein and serum thromboxane (TX)B2 were measured.

RESULTS

In ET patients, VWF:Ag was increased by 31 ± 13% vs. controls (P < 0.01), without dependence of blood groups, while VWF:act was reduced by 21 ± 12% vs. controls and by 50 ± 24% vs. RT (P < 0.01). The VWF:act/VWF:Ag ratios in ET were reduced by 35 ± 17% vs. controls and RT patients (P < 0.001) and significantly associated with: immature or total platelet counts, GC, GpV and TXB2 . In multivariable analysis, only GC inversely predicted ET patients' VWF:act/VWF:Ag ratios (β = -0.42, P = 0.01). By electrophoresis analyses, high-molecular-weight VWF multimers were variably reduced with atypical cleavage bands in ET only. VWF:propeptide, ADAMTS-13 and elastase levels were normal in ET patients. Platelet-associated ADAM-10 and ADAM-17 hydrolyzed VWFm in vitro, showing patterns similar to those in ET samples.

CONCLUSIONS

In ET patients with controlled platelet counts, the VWF:act/VWF:Ag ratio is decreased and predicted by GC, a product of platelet activation. ADAM-10 and/or ADAM-17 might be involved. In vivo platelet activation, which characterizes ET, might contribute to disease-specific VWF alterations.

Role of blood cells dynamism on hemostatic complications in low-risk patients with essential thrombocythemia

Patients with essential thrombocythemia (ET) aged less than 60 years, who have not suffered a previous vascular event (low-risk patients), may develop thrombotic or hemorrhagic events. So far, it has not been possible to identify useful markers capable of predicting which of these patients are more likely to develop an event and therefore who needs to be treated. In the present study, we analysed the relationship between vascular complications and longitudinal blood counts of 136 low-risk ET patients taken over a sustained period of time (blood cells dynamism). After a median follow-up of 60 months, 45 out of 136 patients (33%) suffered 40 major thrombotic and 5 severe hemorrhagic complications. A total number of 5,781 blood counts were collected longitudinally. Thrombotic and hemorrhagic events were studied together (primary endpoint) but also separately (thrombotic alone = secondary endpoint; hemorrhagic alone = tertiary endpoint). The primary endpoint showed no significant association between platelet and WBC count at diagnosis and risk of any event (platelet, p = 0.797; WBC, p = 0.178), while Hb at baseline did show an association (p = 0.024). In the dynamic analysis with Cox regression model, where the blood count values were studied by time of follow-up, we observed that the risk for Hb was 1.49 (95% CI 1.13-1.97) for every increase of 1 g/dL, and that this risk then marginally decreased during follow-up. WBC was associated with an increased risk at baseline for every increase of 1 × 10(9)/L (hazard ratio (HR) 1.07, 95% CI 1.01-1.13, p = 0.034), the risk was stable during follow-up (HR 0.95, p = 0.187 at 60 months). Also, for each increment at baseline of 100 × 10(9) platelets/L, HR was increased by 1.08 (95% CI 0.97-1.22, p = 0.159) and decreases during follow-up. In conclusion, this study is the first to evaluate in ET low-risk patients, the risk of developing a thrombotic/hemorrhagic event considering blood counts over time. Overall our study shows that the risk changes over time. For example, the risk associated with WCC is not linear as previously reported. An interesting new finding is that PLT and even Hb contribute to the risk of developing vascular events. Future treatments should take into consideration these findings and aim to control all parameters over time. We believe this early study may help develop a dynamic analysis model to predict thrombosis in the single patient. Further studies are now warranted to further validate our findings.

Anagrelide platelet-lowering effect is due to inhibition of both megakaryocyte maturation and proplatelet formation: insight into potential mechanisms

BACKGROUND AND OBJECTIVES

Anagrelide represents a treatment option for essential thrombocythemia patients. It lowers platelet counts through inhibition of megakaryocyte maturation and polyploidization, although the basis for this effect remains unclear. Based on its rapid onset of action, we assessed whether, besides blocking megakaryopoiesis, anagrelide represses proplatelet formation (PPF) and aimed to clarify the underlying mechanisms.

METHODS AND RESULTS

Exposure of cord blood-derived megakaryocytes to anagrelide during late stages of culture led to a dose- and time-dependent inhibition of PPF and reduced proplatelet complexity, which were independent of the anagrelide-induced effect on megakaryocyte maturation. Whereas anagrelide was shown to phosphorylate cAMP-substrate VASP, two pharmacologic inhibitors of the cAMP pathway were completely unable to revert anagrelide-induced repression in megakaryopoiesis and PPF, suggesting these effects are unrelated to its ability to inhibit phosphodiesterase (PDE) 3. The reduction in thrombopoiesis was not the result of down-regulation of transcription factors which coordinate PPF, while the myosin pathway was identified as a candidate target, as anagrelide was shown to phosphorylate the myosin light chain and the PPF phenotype was partially rescued after inhibition of myosin activity with blebbistatin.

CONCLUSIONS

The platelet-lowering effect of anagrelide results from impaired megakaryocyte maturation and reduced PPF, both of which are deregulated in essential thrombocythemia. These effects seem unrelated to PDE3 inhibition, which is responsible for anagrelide's cardiovascular side-effects and antiplatelet activity. Further work in this field may lead to the potential development of drugs to treat thrombocytosis in myeloproliferative disorders with an improved pharmacologic profile.

Stalled cerebral capillary blood flow in mouse models of essential thrombocythemia and polycythemia vera revealed by in vivo two-photon imaging

BACKGROUND

Essential thrombocythemia (ET) and polycythemia vera (PV) are myeloproliferative neoplasms (MPNs) that share the JAK2(V617F) mutation in hematopoietic stem cells, leading to excessive production of predominantly platelets in ET, and predominantly red blood cells (RBCs) in PV. The major cause of morbidity and mortality in PV and ET is thrombosis, including cerebrovascular occlusive disease.

OBJECTIVES

To identify the effect of excessive blood cells on cerebral microcirculation in ET and PV.

METHODS

We used two-photon excited fluorescence microscopy to examine cerebral blood flow in transgenic mouse models that mimic MPNs.

RESULTS AND CONCLUSIONS

We found that flow was 'stalled' in an elevated fraction of brain capillaries in ET (18%), PV (27%), mixed MPN (14%) and secondary (non-MPN) erythrocytosis (27%) mice, as compared with controls (3%). The fraction of capillaries with stalled flow increased when the hematocrit value exceeded 55% in PV mice, and the majority of stalled vessels contained only stationary RBCs. In contrast, the majority of stalls in ET mice were caused by platelet aggregates. Stalls had a median persistence time of 0.5 and 1 h in ET and PV mice, respectively. Our findings shed new light on potential mechanisms of neurological problems in patients with MPNs.

[Successful treatment of an essential thrombocythemia patient complicated by Sweet's syndrome with combination of chemotherapy and lenalidomide]

A 79-year-old man had been followed up since July 2003 based on a diagnosis of essential thrombocythemia (ET). The patient visited our hospital after developing a high fever and rash in August 2010, and Sweet's syndrome was diagnosed based on skin biopsy results. The bone marrow aspirate showed features like those of myelodysplastic/myeloproliferative neoplasm (MDS/MPN, unclassifiable). Administration of metenolone and azacitidine was initiated in March and May 2011, respectively, but the rash associated with Sweet's syndrome showed exacerbation. Ranimustine was therefore administered starting in July 2011 to control the blood cell count, but the rash associated with Sweet's syndrome persisted. Combination therapy with lenalidomide was initiated in September 2012, and resulted in control of the blood cell count and marked improvement of Sweet's syndrome.

Transcriptional profiling of whole blood identifies a unique 5-gene signature for myelofibrosis and imminent myelofibrosis transformation

Identifying a distinct gene signature for myelofibrosis may yield novel information of the genes, which are responsible for progression of essential thrombocythemia and polycythemia vera towards myelofibrosis. We aimed at identifying a simple gene signature – composed of a few genes - which were selectively and highly deregulated in myelofibrosis patients. Gene expression microarray studies have been performed on whole blood from 69 patients with myeloproliferative neoplasms. Amongst the top-20 of the most upregulated genes in PMF compared to controls, we identified 5 genes (DEFA4, ELA2, OLFM4, CTSG, and AZU1), which were highly significantly deregulated in PMF only. None of these genes were significantly regulated in ET and PV patients. However, hierarchical cluster analysis showed that these genes were also highly expressed in a subset of patients with ET (n = 1) and PV (n = 4) transforming towards myelofibrosis and/or being featured by an aggressive phenotype. We have identified a simple 5-gene signature, which is uniquely and highly significantly deregulated in patients in transitional stages of ET and PV towards myelofibrosis and in patients with PMF only. Some of these genes are considered to be responsible for the derangement of bone marrow stroma in myelofibrosis. Accordingly, this gene-signature may reflect key processes in the pathogenesis and pathophysiology of myelofibrosis development.

Diagnostic approaches to polycythemia vera in 2004

Four years have passed since publication of the latest update in clinical criteria for the diagnosis of polycythemia vera. During this time, the first molecular markers for polycythemia vera have been described. They include decreased expression of the thrombopoietin receptor, c-Mpl, and overexpression of the polycythemia rubra vera-1 messenger RNA. These biomarkers, which are not in themselves the causative changes leading to disease development but nonetheless appear intricately linked to the pathological process, may constitute a useful addition to our diagnostic repertoire. This review examines both the currently available clinical criteria and the possible role of biomarkers in the diagnosis of polycythemia vera. From this discussion, a refined set of diagnostic criteria for polycythemia vera is proposed.

Thrombosis and risk factors in female patients with a rare acquired thrombophilia: chronic myeloproliferative disorder - polycythaemia vera and essential thrombocythaemia

OBJECTIVE

In polycythaemia vera (PV) and essential thrombocythaemia (ET), the life expectancy of the patients is greatly affected by thrombotic events. An investigation was performed of the potential association of PV/ET, and thrombotic complications with cardiovascular (CV) risk factors, a leukocyte count at the haematological diagnosis > 11.1 G/L, and the JAK2V617F mutation.

PATIENTS AND METHODS

In the period 1998-2011, 128 women with a median age of 62 years were enrolled.

RESULTS

The risk of thrombotic events before the diagnosis was 32.8% (42/128), while in the follow-up period it was 10.2% (13/128). The difference in the probability of thrombosis-free survival between those with at most one CV risk factor and those with two or more CV risk factors was significant (p = 0.005). The presence of two or more CV risk factors (univariate: p = 0.011; multivariate: relative risk: 4.728, 95% CI 1.312-17.040; p = 0.018) significantly increased the risk of thrombosis. Univariate analyses revealed that high blood pressure (p = 0.001), hyperlipidaemia (p = 0.005) and cigarette smoking (p = 0.051) were associated with a significantly higher risk of thrombosis. Analyses of the influence of the leukocyte count (univariate: p = 0.424; multivariate: relative risk: 1.407, 95% CI 0.359-5.507; p = 0.624) and the JAK2V617F mutation (univariate: p = 0.367; multivariate: relative risk: 1.428, 95% CI 0.316-6.460; p = 0.643) on subsequent thrombotic complications resulted in a non-signicant tendency.

CONCLUSIONS

Female patients who display CV risk factors (high blood pressure, hyperlipidaemia and/or cigarette smoking) and PV or ET may well be at a higher risk of thrombotic events and require special consideration as concerns as the prevention and management of thrombotic events.

Circulating endothelial cells in patients with venous thromboembolism and myeloproliferative neoplasms

Background

Circulating endothelial cells (CEC) may be a biomarker of vascular injury and pro-thrombotic tendency, while circulating endothelial progenitor cells (CEP) may be an indicator for angiogenesis and vascular remodelling. However, there is not a universally accepted standardized protocol to identify and quantify these cells and its clinical relevancy remains to be established.

Objectives

To quantify CEC and CEP in patients with venous thromboembolism (VTE) and with myeloproliferative neoplasms (MPN), to characterize the CEC for the expression of activation (CD54, CD62E) and procoagulant (CD142) markers and to investigate whether they correlate with other clinical and laboratory data.

Patients and Methods

Sixteen patients with VTE, 17 patients with MPN and 20 healthy individuals were studied. The CEC and CEP were quantified and characterized in the blood using flow cytometry, and the demographic, clinical and laboratory data were obtained from hospital records.

Results

We found the CEC counts were higher in both patient groups as compared to controls, whereas increased numbers of CEP were found only in patients with MPN. In addition, all disease groups had higher numbers of CD62E+ CEC as compared to controls, whereas only patients with VTE had increased numbers of CD142+ and CD54+ CEC. Moreover, the numbers of total and CD62+ CEC correlated positively with the white blood cells (WBC) counts in both groups of patients, while the numbers of CEP correlated positively with the WBC counts only in patients with MPN. In addition, in patients with VTE a positive correlation was found between the numbers of CD54+ CEC and the antithrombin levels, as well as between the CD142+ CEC counts and the number of thrombotic events.

Conclusions

Our study suggests that CEC counts may reveal endothelial injury in patients with VTE and MPN and that CEC may express different activation-related phenotypes depending on the disease status.

The levels of adhesion molecules in essential thrombocythemia

AIM

It is known that thrombocytosis is closely related to vascular complications and particularly thrombosis in essential thrombocytemia (ET) cases. The aim of this study is to investigate a possible correlation between adhesion molecules and vascular attacks as well as the relation of these molecules to the platelet count.

METHODS

The study group consisted of 30 ET patients and 30 healthy controls subjects. Serum intracellular adhesion molecule-1 (ICAM-1), serum vascular adhesion molecule-1 (VCAM-1) and serum E-selectin levels were determined by ELISA method according to manufacturer's instructions.

RESULTS

There were no significant differences between two groups with respect to levels of sICAM-1 and sE-selectin (P>0.05). The VCAM-1 levels and platelets were significantly higher in patients with ET compared to controls (P=0.000). Spearman's correlation analysis revealed that sVCAM-1 levels were correlated with platelet counts (r=0.574, P<0.001) CONCLUSION: High VCAM-1 level in ET and its correlation with the platelet count suggest that these may be a factor in vascular complications and thrombocytosis.

Thrombotic complications of myeloproliferative neoplasms: risk assessment and risk-guided management

Philadelphia-negative myeloproliferative neoplasms are considered to be acquired thrombophilic states. Thromboses, both arterial and venous (not rarely in unusual sites), are often the initial events leading to the diagnosis. After diagnosis, the yearly incidence of thrombotic events is highly variable, and ranges from approximately 1% to 10%. The identification of patients at risk who may benefit from antithrombotic therapy remains a challenge, and it is currently based on age and history of thrombotic events. However, the predictive value of these clinical characteristics is rather limited. Few prospective studies and even fewer interventional randomized studies are available, and there are no studies designed to formally validate the use of risk stratification. The implementation of laboratory parameters such as leukocytosis and/or the JAK2 V617F mutation into a scoring system may be of interest. The mechanisms at work leading to thrombosis remain largely speculative, but are likely to be complex and multifactorial, with a prominent role of cell-cell interactions, mostly owing to qualitative changes. The long-term treatment options to prevent thrombosis are, schematically, aspirin alone as primary prevention for the low-risk patients, and cytoreduction combined with aspirin for the other patients. In very low-risk young essential thrombocythemia patients, abstention can even be considered. The optimal duration of anticoagulation after a thrombotic event is not established. All antithrombotic therapies should be balanced with the hemorrhagic risk, which can also be increased in these patients.

Open-label, dose-titration and continuation study to assess efficacy, safety, and pharmacokinetics of anagrelide in treatment-naïve Japanese patients with essential thrombocythemia

Although anagrelide is widely used for the treatment of essential thrombocythemia (ET) in the USA and Europe, it is not licensed in Japan. Existing literature has reported differences in polymorphism and activity of CYP1A2 in Japanese and non-Japanese ethnic groups, which may alter anagrelide metabolism. We intended to identify the optimum dosage of anagrelide in treatment-naïve Japanese patients with ET and assess its long-term safety and efficacy. Twelve patients with ET and a platelet count of ≥ 80 × 10(4)/μL were enrolled. Anagrelide was administered at an initial dose of 0.5 mg/day (weeks 1-4), then increased to 1.0 mg/day (weeks 5-8). During the following maintenance (weeks 9-52) and continuation periods (weeks 53-104), the dose was adjusted according to patient safety data and to maintain target platelet counts (<60 × 10(4)/μL). Increasing the dose led to a decrease in mean platelet count, and target platelet counts were maintained in 11 patients. Adverse events were mild or moderate, and none led to discontinuation. This cohort of Japanese patients exhibited higher pharmacokinetic exposures of anagrelide and its active metabolite than those previously documented in non-Japanese patients. These differences were modest, suggesting specific dosing regimens for Japanese patients are not required.

JAK2-v617F mutation is associated with clinical and laboratory features of myeloproliferative neoplasms

The aim of this study is to investigate the differences of clinical and laboratory parameters between patients with JAK2-V617F positive myeloproliferative neoplasms (MPNs) and JAK2 wild type MPNs. DNA was isolated from peripheral blood granulocytes of 106 patients treated at Rijeka University Hospital Center: 41 with polycythemia vera (PV), 43 with essential thrombocythemia (ET), 9 with primary myelofibrosis (PMF) and 13 with myeloproliferative neoplasm--unclassifiable (MPN-u). The JAK2-V617F mutation was detected using allele specific PCR. Laboratory and clinical parameters were obtained from patient's medical records. The JAK2-V617F mutation was detected in 69% (73/106) patients with MPNs. The results revealed significantly different prevalence of JAK2-V617F mutation, between MPNs entities: 88% in PV 58% in ET, 56% in PMF and 54% in MPNs-unclassified disorders. The JAK2-V617F mutation significantly correlated with higher leukocyte count and alkaline phosphatase co re in ET group and with higher platelets count, leukocyte alkaline phosphatase score and serum lactate dehydrogenase in PV group. Vascular events were associated with elevated platelets count in whole MPNs group, with higher platelets and leukocyte count in ET and with splenomegaly in PVpatients. Clinical and laboratory data revealed significant contribution ofJAK2-V617F mutation to the development of clinical phenotype in patients with distinct subgroups of MPNs.

Evaluation of interleukin-23 plasma levels in patients with polycythemia vera and essential thrombocythemia

Essential thrombocythemia (ET), polycythemia vera (PV) and myelofibrosis share the same acquired genetic lesion, JAK2V617F. It is believed that cytokines participate in the activation of JAK2V617F. In this study, we analyzed the plasma levels of interleukin (IL)-23, IL-10 and IL-22 in patients with PV and ET. In the same subjects we also performed analysis of the JAK2(V617F) mutation, and evaluated a possible relationship between interleukin levels and thrombotic complications or with the symptom pruritus. Plasma levels of IL-23 were significantly increased in all patients with MPN in comparison to controls. Moreover, there was a significant difference between the levels of IL-23 in patients affected by PV and those measured in controls (8.57±3.69pg/mL vs. 6.55±4.125pg/mL; p<0.03). No difference was found between IL-23 levels in ET patients and controls. No statistically significant differences were found between the levels of IL-23, Il-22 or IL-10 in PV or ET subjects with or without thrombosis, in patients with or without pruritus, or according the JAK2V617F burden. In PV patients the JAK2 burden and Hb levels correlated with occurrence of pruritus. Our study seems to point out a possible involvement of IL-23 in the pathogenesis of PV.

[The quantitative evaluation of mutation V617F of gene JAK2 under chronic myeloproliferative diseases]

The mutation V617F of gene JAK2 is detected in 95% of patients with genuine polycythemia, in 50% of patients with essential thrombocytemia and idiopathic myelofibrosis. The mutation V617F can be applied as a molecular marker of response to treatment in patients with chronic myeloproliferative diseases associated with this mutation. The technique of quantitative evaluation of V617F (sensitivity up to 0.01%) using polymerase chain reaction is described. This method can be applied to assess the minimal residual disease in patients with chronic myeloproliferative diseases.

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

DISEASE OVERVIEW

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

DIAGNOSIS

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

RISK STRATIFICATION

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

RISK-ADAPTED THERAPY

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

Circulating endothelial cells and endothelial activation in essential thrombocythemia: results from CD146+ immunomagnetic enrichment--flow cytometry and soluble E-selectin detection

Circulating endothelial cells (CECs) have been studied in cardiovascular disorders and as a marker of angiogenetic activity; clinical applications are limited by a lack of consensus on their phenotypic identification and quantification. We determined CECs in essential thrombocythemia (ET) patients, to investigate their possible pathogenetic role. We considered CECs as CD146⁺/CD45⁻ nucleated cells, detected in peripheral blood from 21 healthy controls and 39 ET patients, performing a combination of pre-enrichment of CD146⁺ circulating cells and multiparametric flow cytometry measurement (FCM). Levels of CECs in ET patients were higher with respect to controls (median 2844 CECs/mL vs. 121.3 CECs/mL, P < 0.0001). Apparently hydroxyurea treatment did not influence the levels of CECs. As another established marker of endothelial activation, we also assessed soluble E-selectin (sE-selectin) levels in 31 of the ET patients and compared with 39 healthy volunteers: median sE-selectin level in ET patients was 35.3 ng/mL, higher with respect to controls (24.48 ng/mL), P = 0.0369. Our data suggest that endothelium in ET is activated, reflecting a significant role of angiogenesis in this disorder and suggesting an important endothelial contribution in the hypercoagulable state of ET patients.

Clinical implications of elevated antiphospholipid antibodies in adult patients with primary immune thrombocytopenia

BACKGROUND/AIMS

Antiphospholipid antibodies (aPL) have been detected in various proportions of patients with primary immune thrombocytopenia (ITP), but the clinical significance of this is debatable. The present study aimed to determine the frequency and clinical implications of elevated aPL in adult patients with ITP.

METHODS

We prospectively studied newly diagnosed adult patients with ITP who were enrolled between January 2003 and December 2008 at Chungnam National University Hospital. They were evaluated for the presence of lupus anticoagulant (LA) and anticardiolipin antibodies (aCL) at diagnosis and were followed for the development of thrombosis.

RESULTS

Seventy consecutive patients with ITP (median age, 48 years; range, 18 to 79) were enrolled. Twenty patients (28.5%) were positive for aPL at the time of diagnosis: aCL alone in 15 (75%), aCL and LA in two (10%), and LA alone in three (15%). Patients who had platelet counts < 50,000/µL were administered oral prednisolone with or without intravenous immune globulin. No difference was found between the aPL-positive and -negative groups regarding gender, initial platelet count, and response to the therapy. After a median follow-up of 20 months (range, 2 to 68), two of 20 patients who were aPL-positive (10%) developed thrombosis, whereas no thrombotic event was found among those who were aPL-negative.

CONCLUSIONS

Our data suggest that aPL levels should be determined at the initial presentation of ITP and that patients found to be aPL-positive should receive closer follow-up for thrombotic events.

[Two clinical cases of essential thrombocythemia complicated by thrombosis in parturients]

The paper describes two clinical cases of essential thrombocythemia (ET) complicated by thrombosis in parturients. ET was diagnosed only postpartum when thrombotic complications occurred. Both patients received anagrelid as first-line therapy, as well as Clexane and oral anticoagulants. It is shown that even in younger ET patients with low-risk pregnancies thrombosis and inflammation may be a stimulus to serious thrombotic complications and require special attention.

Platelet-induced thrombin generation by the calibrated automated thrombogram assay is increased in patients with essential thrombocythemia and polycythemia vera

The platelet contribution to the thrombophilic state of patients with myeloproliferative neoplasms (MPNs), i.e., essential thrombocythemia (ET) and polycythemia vera (PV), remains uncertain. In this study we aimed to characterize the thrombin generation (TG) potential expressed by platelets from these subjects, compare it to normal platelets, and identify what factors might be responsible for platelet TG. In a group of 140 MPN patients (80 ET and 60 PV) and 72 healthy subjects, we measured the global procoagulant potential of platelet-rich plasma (PRP) utilizing the TG assay by the calibrated automated thrombogram (CAT). To characterize the procoagulant contribution of platelets in PRP, the TG of both isolated platelets and platelet-poor plasma was measured, and the platelet surface expression of TF was determined. Finally, the activation status of platelets was assessed by the levels of P-selectin expressed on platelet surface. MPN patients had significantly increased PRP and isolated platelet TG potential compared to controls. This was associated to the occurrence of platelet activation. Patients carriers of the JAK2V617F mutation showed the highest values of TG and platelet surface TF and P-selectin. Platelet TG potential was significantly lower in hydroxyurea(HU) compared to non-HU-treated patients and was lowest in HU-treated JAK2V617F carriers. In subjects not receiving HU, platelet TG significantly increased by JAK2V617F allele burden increment (P < 0.05).This study demonstrates a platelet-dependent form of hypercoagulability in MPN patients, particularly in those carriers of the JAK2V617F mutation. The cytoreductive therapy with HU significantly affects this prothrombotic phenotype.

[Essential thrombocythaemia and other myeloproliferative disorders with thrombocythaemia treated with Thromboreductin. A report from the database of register for the 1st quarter of 2010]

In the Czech Republic, anagrelid is used according to the recommendations of the Czech Working Group on Myeloproliferative Disorders for treatment ofthrombocythaemias associated with chronic myeloproliferative disorders--mainly essential thrombocythaemia and, regularly, reports are being presented from the Register of Patients Treated with Thromboreductin, most recently last year (Vnitr Lék 2009; 55: I-XII). The Register commenced in 2005 and from then it aims to determine detailed clinical and laboratory profiles of the patients. The structure of the Register has changed significantly in the course of its existence, reflecting the reports from each of the analyses conducted so far. Also, the data entry in the database improves every year and it reaches 97% on some of the items. The longest evaluation period in some of the patients is 108 months. By April 2010, the Register database contained data on 717 patients. Of these, 672 patients with the diagnosis of a Ph-negative chronic myeloproliferative disorder were evaluated. This year's analysis included the patients with essential thrombocythaemia, polycythaemia vera and primary myelofibrosis only. The analysis included 418 women and 254 men with median age of50 years. Unlike the first years, 2/3 of the current sample are non pretreated patients, meaning that the patients reach the specialized centres early in their treatment. Also, patients, and the older patients in particular, are more frequently treated with combined regimens including Thromboreductin. We increasingly observe hypertension as one of the monitored risk factors preceding the disease and laboratory parameters showJAK2 mutation in more than a half of patients while some form ofthrombotic diathesis is found in the anamnesis of 7-10% of patients. Some bleeding is observed in 1-5% of the registered patients. In comparison to the previous years, this is a decrease in the prevalence of clinical symptoms prior to the disease onset; this is very likely associated with an earlier patient diagnosis within the asymptomatic phase of the disease. Therapeutically, we achieve a fast treatment response but there still are 16.3% of sufficient afterone year of treatment. Thromboreductin dose is increasing but even in this group it does not exceeds the mean of 2.38 mg per 24 hours. Complications are observed in 6.2% of patients in the first year of therapy, and ofthese, thrombotic events in about 2.5% and (small) bleeding complications in 4% of patients. The data suggest that we still do not reach treatment response in a certain proportion of patients after a year of their therapy. Even though the care results from the analysed data improve every year, the Register helps to uncover some issues that still remain, such as treatment intensification and other treatment modifications.

Leukocytosis is a risk factor for recurrent arterial thrombosis in young patients with polycythemia vera and essential thrombocythemia

There is evidence that leukocytosis is associated with an increased risk of first thrombosis in patients with polycythemia vera (PV) and essential thrombocythemia (ET). Whether it is a risk factor for recurrent thrombosis too is currently unknown. In the frame of a multicenter retrospective cohort study, we recruited 253 patients with PV (n = 133) or ET (n = 120), who were selected on the basis of a first arterial (70%) or venous major thrombosis (27.6%) or both (2.4%), and who were not receiving cytoreduction at the time of thrombosis. The probability of recurrent thrombosis associated with the leukocyte count recorded at the time of the first thrombosis was estimated by a receiver operating characteristic analysis and a multivariable Cox proportional hazards regression model. Thrombosis recurred in 78 patients (30.7%); multivariable analysis showed an independent risk of arterial recurrence (hazard ratio [HR] 2.16, 95% CI 1.12-4.18) in patients with a leukocyte count that was >12.4 x 10(9)/L at the time of the first thrombotic episode. The prognostic role for leukocytosis was age-related, as it was only significant in patients that were aged <60 years (HR for arterial recurrence 3.35, 95% CI 1.22-9.19).

Blast phase of essential thrombocythemia: A single center study

Blast phase (BP) may occur as a late event in essential thrombocythemia (ET). This study includes 19 patients with post-ET BP diagnosed and followed in a single institution. At BP, 63% of patients had leukocytosis (white blood cell count >10 x 10(9)/L), 74% had anemia (hemoglobin value <10 g/dL), 74% had thrombocytopenia (platelet count <100 x 10(9)/L), and 84% were over 65 years of age. Cytogenetic analysis was available in 10 patients: six had karyotype aberrations. According to cytogenetic-based risk stratification of de novo acute leukemia (AL), all patients had an unfavorable profile. JAK2 (V617F) mutational status was evaluated in five patients. In two of them, the JAK2 mutation was undetectable in blast cells (one with JAK2-positive ET), whereas in three both granulocytes and blast cells displayed the mutation. Treatment of BP was patient-based according to the performance status and co-morbidities and consisted of palliation in 14 patients, and of induction of remission in five. Median survival was 2.3 months (range 0.2-22.3), irrespective of the treatment received. In conclusion, this study indicates that AL evolved from ET has unfavorable clinical and biological features. JAK2 (V617F)-positive ET may evolve in few instances into JAK2-negative leukemia. The outcome of patients is poor whatever the treatment used.