Long-term pharmacodynamic and clinical effects of twice- versus once-daily low-dose aspirin in essential thrombocythemia: The ARES trial.

Patients with essential thrombocythemia (ET) are treated with once-daily low-dose aspirin to prevent thrombosis, but their accelerated platelet turnover shortens the antiplatelet effect. The short-term Aspirin Regimens in EsSential Thrombocythemia trial showed that twice-daily aspirin dosing restores persistent platelet thromboxane (TX) inhibition. However, the long-term pharmacodynamic efficacy, safety and tolerability of twice-daily aspirin remain untested. We performed a multicenter, randomized, open-label, blinded-endpoint, phase-2 trial in which 242 patients with ET were randomized to 100 mg aspirin twice- or once-daily and followed for 20 months. The primary endpoint was the persistence of low serum TXB2, a surrogate biomarker of antithrombotic efficacy. Secondary endpoints were major and clinically relevant non-major bleedings, serious vascular events, symptom burden assessed by validated questionnaires, and in vivo platelet activation. Serum TXB2 was consistently lower in the twice-daily versus once-daily regimen on 10 study visits over 20 months: median 3.9 ng/mL versus 19.2 ng/mL, respectively; p < .001; 80% median reduction; 95% CI, 74%-85%. No major bleeding occurred. Clinically relevant non-major bleedings were non-significantly higher (6.6% vs. 1.7%), and major thromboses lower (0.8% vs. 2.5%) in the twice-daily versus once-daily group. Patients on the twice-daily regimen had significantly lower frequencies of disease-specific symptoms and severe hand and foot microvascular pain. Upper gastrointestinal pain was comparable in the two arms. In vivo platelet activation was significantly reduced by the twice-daily regimen. In patients with ET, twice-daily was persistently superior to once-daily low-dose aspirin in suppressing thromboxane biosynthesis and reducing symptom burden, with no detectable excess of bleeding and gastrointestinal discomfort.

Thrombopoietin receptor agonists increase splenic regulatory T-cell numbers in immune thrombocytopenia.

Thrombopoietin receptor agonists (TPO-RA) are a valid therapy for immune thrombocytopenia (ITP), due to megakaryocyte stimulation and (poorly characterised) immune-modulatory effects. The spleen is pivotal in the pathogenesis of ITP, yet little is known on its immune microenvironment and on effects of TPO-RA on this organ. To address these topics, we analysed 35 spleens removed for primary refractory ITP. Pre-splenectomy TPO-RA administration correlated with increased splenic regulatory T cells (Tregs), type 2 T-helper cells and histiocyte density and with reduced red pulp sinusoids. Surgical outcome was not associated with TPO-RA administration, other pre-splenectomy therapies and/or Treg density. In conclusion, TPO-RA affect the splenic microenvironment, but this has no impact on splenectomy outcome.

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).

Histology of the spleen in immune thrombocytopenia: clinical-pathological characterization and prognostic implications.

OBJECTIVE: Immune thrombocytopenia (ITP) is an acquired disorder, characterized by immune-mediated platelet destruction. The spleen plays a key pathogenic role in ITP and splenectomy is a valuable second-line therapy for this disease. Little is known on ITP spleen histology and response to splenectomy is unpredictable. This study aims to characterize ITP spleen histology and assess possible predictors of splenectomy outcome. METHODS: A series of 23 ITP spleens were retrospectively assessed for the following histological parameters: density of lymphoid follicles (LFs), marginal zones (MZs), T helper and cytotoxic T cells; presence of reactive germinal centers (GCs); width of perivascular T cell sheaths; and red pulp features. Clinical and histological data were matched with postsplenectomy platelet counts to assess their prognostic relevance. RESULTS: Three histological patterns were documented: a hyperplastic white pulp pattern, a non-activated white pulp pattern (lacking GCs), and a white pulp-depleted pattern. Poor surgical responses were associated with presplenectomy high-dose steroid administration, autoimmune comorbidities and low T follicular helper cell density. The combination of such parameters stratified patients into different splenectomy response groups. The removal of accessory spleens was also associated with better outcome. CONCLUSION: ITP spleens are histologically heterogeneous and clinical-pathological parameters may help predict the splenectomy outcome.

Systemic Mastocytosis and Essential Thrombocythemia: Case Report and Literature Overview.

Mastocytosis is a rare disease in which heightened amounts of mast cells accumulate in the skin, bone marrow, and other visceral organs. Upon activation, mast cells release a wide variety of preformed or newly synthesized mediators which can induce allergic symptoms and inflammatory reactions. Mastocytosis is diagnosed by biopsy and can be divided into cutaneous and systemic mastocytosis (SM). The first one affects the skin and is relatively benign, whilst SM, which involves bone marrow and other organs, may be aggressive and associate with both myelodisplastic and myeloproliferative diseases. Here we present a case of SM associated with essential thrombocythemia and complicated by severe osteoporosis, successfully treated with hydroxyurea, low-dose aspirin and zolendronic acid.

Thromboses and hemorrhages are common in MPN patients with high JAK2V617F allele burden.

The most common causes of morbidity and mortality in myeloproliferative neoplasms (MPN) are thrombotic and hemorrhagic complications. The JAK2V617F mutation, commonly found in MPN, correlates with several clinical and laboratory characteristics even if the relevance of JAK2V617F allele burden in the natural history of these diseases is unclear. In this study we searched, a relation between thrombotic and hemorrhagic complications and JAK2V617F allele burden level in MPN patients. We evaluated 253 consecutive MPN [121 essential thrombocythemia (ET), 124 polycythemia vera (PV), and 8 primary myelofibrosis (PMF)] patients in whom the JAK2V617F allele burden was available, all studied and followed (median 8.8 years) in our department. Patients were stratified accordingly to their JAK2V617F allele burden, into four quartiles (1st <25%, 2nd 26-50%, 3rd 51-75%, and 4th >75%). Significantly higher incidence of thromboses (p = 0.001) and hemorrhages (p < 0.001) during follow-up has been observed in higher quartiles when compared to lower ones. Thrombosis- and hemorrhage-free survivals were poorer in patients belonging to the highest quartile. Our data suggest that MPN patients with JAK2V617F allele burden higher than 75% have to be considered as high risk patients, being prone to develop thrombo-hemorrhagic complications during the disease course.

Thrombotic risk correlates with mutational status in true essential thrombocythemia.

BACKGROUND: 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. MATERIALS AND METHODS: 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). RESULTS: 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. CONCLUSION: 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.

Idiopathic erythrocytosis: a study of a large cohort with a long follow-up.

Idiopathic erythrocytosis (IE) is an absolute erythrocytosis with no known cause, diagnosed by exclusion of primary and secondary erythrocytosis. Familial erythrocytosis (FE) is a rare disease and as the rare patients with JAK2-wild-type polycythemia vera (PV) may be misdiagnosed as IE. We compared 78 patients with IE, 21 with FE and 136 with PV in the effort to identify simple features capable of discriminating between them. FE patients were younger at diagnosis either than IE and PV (p < 0.001); IE and FE had lower WBC, platelet counts and higher serum EPO levels, and had splenomegaly and thrombotic events less frequently than PV patients. Phlebotomies to obtain a haematocrit lower than 45 % induce platelet count increase in 70 % of PV but not in IE. Mainly in men, normal spleen, normal platelet counts and no history of thrombosis at diagnosis argue against PV; diagnosis of IE could be supported by means of a cycle of venesection to see how it affects their platelet count. No simple data capable of distinguishing between IE and FE were identified; therefore, a case of sporadic erythrocytosis in a young patient should be investigated as a possible genetic cause.

Are all cases of paediatric essential thrombocythaemia really myeloproliferative neoplasms? Analysis of a large cohort.

Sporadic essential thrombocythaemia (ET) is rare in paediatrics, and the diagnostic and clinical approach to paediatric cases cannot be simply copied from experience with adults. Here, we assessed 89 children with a clinical diagnosis of ET and found that 23 patients (25·8%) had a clonal disease. The JAK2 V617F mutation was identified in 14 children, 1 child had the MPL W515L mutation, and 6 had CALR mutations. The monoclonal X-chromosome inactivation pattern was seen in six patients (two with JAK2 V617F and two with CALR mutations). The other 66 patients (74·2%) had persistent thrombocytosis with no clonality. There were no clinical or haematological differences between the clonal and non-clonal patients. The relative proportion of ET-specific mutations in the clonal children was much the same as in adults. The higher prevalence of non-clonal cases suggests that some patients may not have myeloproliferative neoplasms, with significant implications for their treatment.

A lower intensity of treatment may underlie the increased risk of thrombosis in young patients with masked polycythaemia vera.

In patients who do not meet the World Health Organization (WHO) criteria for overt polycythaemia vera (PV), a diagnosis of masked PV (mPV) can be determined. A fraction of mPV patients may display thrombocytosis, thus mimicking essential thrombocythaemia (ET). No previous studies have examined clinical outcomes of mPV among young JAK2-mutated patients. We analysed a retrospective cohort of 538 JAK2-mutated patients younger than 40 years, after a re-assessment of the diagnosis according to the haemoglobin threshold for mPV. In this cohort of patients, 97 (18%) met the WHO criteria for PV, 66 patients (12%) were classified as mPV and 375 (70%) as JAK2-mutated ET. Surprisingly, a significant difference in the incidence of thrombosis was found when comparing mPV versus overt PV patients (P = 0·04). In multivariate analysis, the only factor accounting for the difference in the risk of thrombosis was the less frequent use of phlebotomies and cytoreduction in mPV patients compared to those with overt PV. Thus, we emphasize the need for the identification of mPV in young JAK2-mutated patients in order to optimize their treatments.

Disease characteristics and clinical outcome in young adults with essential thrombocythemia versus early/prefibrotic primary myelofibrosis.

In the present study, we investigated disease characteristics and clinical outcome in young patients (< 40 years) with World Health Organization (WHO)-defined essential thrombocythemia (ET) compared with early/prefibrotic primary myelofibrosis (PMF) with presenting thrombocythemia. We recruited 213 young patients (median age, 33.6 years), including 178 patients (84%) with WHO-defined ET and 35 patients (16%) showing early PMF. Median follow-up time was 7.5 years. A trend for more overall thrombotic complications, particularly arterial, was seen in early PMF compared with ET. Progression to overt myelofibrosis was 3% in ET and 9% in early PMF, but no transformation into acute leukemia was observed. Combining all adverse events (thrombosis, bleeding, and myelofibrosis), the rate was significantly different (1.29% vs 3.43% of patients/year, P = .01) in WHO-ET and early PMF, respectively. In multivariate analysis, early PMF and the JAK2V617F mutation emerged as independent factors predicting cumulative adverse events.

Development and validation of an International Prognostic Score of thrombosis in World Health Organization-essential thrombocythemia (IPSET-thrombosis).

Accurate prediction of thrombosis in essential thrombocythemia (ET) provides the platform for prospective studies exploring preventive measures. Current risk stratification for thrombosis in ET is 2-tiered and considers low- and high-risk categories based on the respective absence or presence of either age > 60 years or history of thrombosis. In an international study of 891 patients with World Health Organization (WHO)-defined ET, we identified additional independent risk factors including cardiovascular risk factors and JAK2V617F. Accordingly, we assigned risk scores based on multivariable analysis-derived hazard ratios (HRs) to age > 60 years (HR = 1.5; 1 point), thrombosis history (HR = 1.9; 2 points), cardiovascular risk factors (HR = 1.6; 1 point), and JAK2V617F (HR = 2.0; 2 points) and subsequently devised a 3-tiered prognostic model (low-risk = < 2 points; intermediate-risk = 2 points; and high-risk = > 2 points) using a training set of 535 patients and validated the results in the remaining cohort (n = 356; internal validation set) and in an external validation set (n = 329). Considering all 3 cohorts (n = 1220), the 3-tiered new prognostic model (low-risk n = 474 vs intermediate-risk n = 471 vs high-risk n = 275), with a respective thrombosis risk of 1.03% of patients/y versus 2.35% of patients/y versus 3.56% of patients/y, outperformed the 2-tiered (low-risk 0.95% of patients/y vs high-risk 2.86% of patients/y) conventional risk stratification in predicting future vascular events.

Initial bone marrow reticulin fibrosis in polycythemia vera exerts an impact on clinical outcome.

We examined the prevalence and prognostic relevance of bone marrow reticulin fibrosis in 526 patients with World Health Organization-defined polycythemia vera evaluated at the time of initial diagnosis. Seventy-four patients (14%) displayed mostly grade 1 reticulin fibrosis, with only 2 cases showing higher-grade fibrosis. Presenting clinical and laboratory characteristics, including JAK2V617F allele burden, between patients with and without fibrosis were similar for the most part, with the exception of a higher prevalence of palpable splenomegaly in patients with fibrosis (P < .01). Patients with fibrosis were less prone to experience thrombosis during their clinical course (1.1 vs 2.7 per 100 patient-years; P = .03) and more prone to develop post-polycythemia vera myelofibrosis (2.2 vs 0.8 per 100 patient-years; P = .01). There was no significant difference between the 2 groups in terms of overall or leukemia-free survival. The present study clarifies the incidence, degree, and prognostic relevance of bone marrow fibrosis obtained at time of initial diagnosis of polycythemia vera.

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

Diagnosis of essential thrombocythemia (ET) has been updated in the last World Health Organization (WHO) classification. We developed a prognostic model to predict survival at diagnosis, named IPSET (International Prognostic Score for ET), studying patients with WHO-defined ET. Age 60 years or older, leukocyte count ≥ 11 × 10(9)/L, and prior thrombosis significantly affected survival, by multivariable Cox regression. On the basis of the hazard ratio, we assigned 2 points to age and 1 each to leukocyte count and thrombosis. So, the IPSET model allocated 867 patients into 3 risk categories with significantly different survival: low (sum of points = 0; median survival not reached), intermediate (sum = 1-2; median survival 24.5 years), and high (sum = 3-4, median survival 13.8 years). The IPSET model was further validated in 2 independent cohorts including 132 WHO-defined ET and 234 Polycythemia Vera Study Group-defined ET patients. The IPSET model was able to predict the occurrence of thrombosis, and not to predict post-ET myelofibrosis. In conclusion, IPSET, based on age ≥ 60 years, leukocyte count ≥ 11 × 10(9)/L, and history of thrombosis allows prognostic assessment of WHO-defined ET and the validation process makes IPSET applicable in all patients phenotypically appearing as ET.

Pregnancy complications predict thrombotic events in young women with essential thrombocythemia.

Although Philadelphia-negative myeloproliferative neoplasms (MPNs) occur typically in middle to advanced age, any age group may be affected, posing a challenge for their management during pregnancy when they occur in young females. There is a high incidence of thromboembolic events and pregnancy complications in patients with myeloproliferative neoplasms, and a possible relationship between these complications is a matter of concern. The aim of this article was to correlate thrombosis and pregnancy outcome in 158 females with ET experiencing 237 pregnancies. Seven patients had a thrombotic event before their first pregnancy, one of them ended (14.3%) in a miscarriage. Among the 151 patients with no history of thrombosis before they became pregnant, 40 (26.5%) had a miscarriage (P = NS). Eighteen patients (11.4%) developed major thrombotic complications (12 splanchnic vein, 1 cerebral vein, 2 coronary syndromes, and 3 strokes) after at least one pregnancy (4 uneventful and 14 complicated). The occurrence of thrombosis was significantly more frequent (P < 0.001) in patients with a history of pregnancy complications (28%) than in those experiencing a normal pregnancy and delivery (3.7%). Pregnancy complications in women with ET are associated with a higher risk of subsequent thromboses, so pregnant women with this neoplasm who miscarry need to be carefully monitored.

Masked polycythemia vera (mPV): results of an international study.

We examined the baseline features and clinical outcomes of 140 patients presenting with JAK2V617F positivity and a bone marrow morphology conforming with WHO criteria of polycythemia vera (PV), but a hemoglobin level of <18.5 g/dL in males (range 16.0-18.4) and <16.5 g/dL in females (range 15.0-16.4). This cohort operationally referred to as masked PV (mPV) was compared with 257 patients with overt PV and displayed male predominance, a more frequent history of arterial thrombosis and thrombocytosis. Incidence of thrombosis was similar between the two groups but mPV displayed significantly higher rates of progression to myelofibrosis and acute leukemia and inferior survival. In multivariable analysis mPV diagnosis was an independent predictor of poor survival along with age >65 years and leukocyte count >10 × 10(9) /L. Our data suggest that mPV is a heterogeneous myeloproliferative neoplasia and not necessarily an early/ pre-polycythemic form of classical PV that at onset in a small fraction of patients clinically may mimic essential thrombocythemia. On the other hand, the majority mPV may have a longer prodrome of undiagnosed PV or a disease biology akin to primary myelofibrosis-post PV myelofibrosis that could explain the worsening of outcome in comparison to overt/classical manifestations.

Discrepant ratios of arterial versus venous thrombosis in hemophilia A as compared with hemophilia B.

The occurrence of thrombosis in patients with congenital bleeding disorders represents an exceptional event. Hemophilia A and hemophilia B patients have been showed to present both arterial and venous thrombosis (85 cases of arterial thrombosis and 34 cases of venous thrombosis). The great majority of arterial thrombosis are myocardial infarction or other acute coronary syndromes, whereas the majority of venous thrombosis are deep vein thrombosis and/or pulmonary embolisms. However there are discrepancies in the proportion of arterial and venous thrombosis seen in hemophilia A versus hemophilia B. The ratio of arterial versus venous thrombosis in hemophilia A is 3.72 whereas that for hemophilia B is 1.12. This indicates that arterial thrombosis is more frequent in hemophilia A as compared to hemophilia B and the opposite is true for venous thrombosis. The potential significance of this discrepancy is discussed.

Coexistence of Multiple Gene Variants in Some Patients with Erythrocytoses.

Background: Erythrocytosis is a relatively common condition; however, a large proportion of these patients (70%) remain without a clear etiologic explanation. Methods: We set up a targeted NGS panel for patients with erythrocytosis, and 118 sporadic patients with idiopathic erythrocytosis were studied. Results: In 40 (34%) patients, no variant was found, while in 78 (66%), we identified at least one germinal variant; 55 patients (70.5%) had 1 altered gene, 18 (23%) had 2 alterations, and 5 (6.4%) had 3. An altered HFE gene was observed in 51 cases (57.1%), EGLN1 in 18 (22.6%) and EPAS1, EPOR, JAK2, and TFR2 variants in 7.7%, 10.3%, 11.5%, and 14.1% patients, respectively. In 23 patients (19.45%), more than 1 putative variant was found in multiple genes. Conclusions: Genetic variants in patients with erythrocytosis were detected in about 2/3 of our cohort. An NGS panel including more candidate genes should reduce the number of cases diagnosed as "idiopathic" erythrocytosis in which a cause cannot yet be identified. It is known that HFE variants are common in idiopathic erythrocytosis. TFR2 alterations support the existence of a relationship between genes involved in iron metabolism and impaired erythropoiesis. Some novel multiple variants were identified. Erythrocytosis appears to be often multigenic.