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Concept: Essential thrombocytosis


Evaluation of Xagrid® Efficacy and Long-term Safety, a Phase IV, prospective, non interventional study performed in 13 European countries enrolled high risk essential thrombocythemia patients treated with cytoreductive therapy. Primary objectives were safety and pregnancy outcomes. Of 3721 registered patients, 3649 received cytoreductive therapy. At registration, 3611 were receiving: anagrelide (Xagrid®) (n=804), other cytoreductive therapy (n=2666), anagrelide + other cytoreductive therapy (n=141). Median age was 56 vs 70 years for anagrelide vs other cytoreductive therapy. Event rates (patients with events/100 patient years) were, for total thrombosis 1.62 vs 2.06, venous thrombosis 0.15 vs 0.53. Anagrelide was more commonly associated with hemorrhage (0.89 vs 0.43), especially with anti-aggregatory therapy (1.35 vs 0.33) and myelofibrosis (1.04 vs 0.30). Other cytoreductive therapies were more associated with acute leukemia (AL) (0.28 vs 0.07) and other malignancies (1.29 vs 0.44). Post-hoc multivariate analyses identified increased risk for thrombosis with prior thrombohemorrhagic events, age ≥65, cardiovascular risk factors, or hypertension. Risk factors for transformation were prior thrombohemorrhagic events, age ≥65, time since diagnosis, and platelet count increase. Safety analysis reflected published data and no new safety concerns for anagrelide were found. Live births occurred in 41/54 pregnancies (76%). ( #NCT00567502).

Concepts: Scientific method, Blood, Observational study, Platelet, Multivariate statistics, Essential thrombocytosis, Phase IV, Anagrelide


Recombinant IFN-α (rIFN-α) induces complete hematologic remissions in patients with myeloproliferative neoplasms (MPNs), but its use has been limited by side effects owing to the relatively high doses used. Now, low-dose rIFN-α is stressed, starting relatively early in the course of the MPNs. In polycythemia vera, this has resulted in a significant clinical, hematologic, morphologic and molecular response manifested by reduction in the JAK2(V617F) allele burden, sustained even after discontinuation of recombinant IFN. In essential thrombocythemia, platelet count reduction is prompt and durable without treatment for varying periods. In hypercellular primary myelofibrosis, rIFN-α has restored normal blood counts, reduced splenomegaly and induced morphologic marrow remissions. This article highlights our current use of rIFN-α in MPNs.

Concepts: Blood, Red blood cell, Platelet, Hematology, Splenomegaly, Myeloproliferative disease, Myelofibrosis, Essential thrombocytosis


The recent discovery of mutations of the gene calreticulin has allowed raising the proportion of patients with essential thrombocythemia and primary myelofibrosis with known mutational abnormality up to 85-90%. Knowledge of the mechanisms by which mutated calreticulin underlie a myeloproliferative neoplasm as well as the clinical and therapeutic implications is just at the very beginning, and exciting times await research in this field.

Concepts: DNA, Cancer, Mutation, DNA repair, Point mutation, Myeloproliferative disease, Myelofibrosis, Essential thrombocytosis


Myeloproliferative neoplasms are clonal hematopoietic disorders that manifest as expansion of one or more myeloid lineages. The most common myeloproliferative neoplasms are chronic myeloid leukemia (CML), polycythemia vera, essential thrombocythemia, and primary myelofibrosis. Whereas the genetic basis for CML has been known for more than 30 years, the specific genetic events that contribute to the pathogenesis of polycythemia vera, essential thrombocythemia, and primary myelofibrosis remained unknown until 2005. Our first insight into the molecular cause of these disorders came when the somatic JAK2 V617F mutation(1)-(4) was identified in the majority of patients with polycythemia vera and in a subset . . .

Concepts: Hematology, Leukemia, Acute myeloid leukemia, Blood disorders, Chronic myelogenous leukemia, Myeloproliferative disease, Myelofibrosis, Essential thrombocytosis


Vascular events represent the most frequent complications of thrombocytemias. We aimed to evaluate their risk in the WHO histologic categories of Essential Thrombocytemia (ET) and early Primary Myelofibrosis (PMF).

Concepts: Histology, Greek loanwords, Myelofibrosis, Essential thrombocytosis


Patients with Ph-negative myeloproliferative neoplasms (MPN), such as polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), are at increased risk for thrombosis/thromboembolism and major bleeding. Due to the morbidity and mortality of these events, antiplatelet and/or anticoagulant agents are commonly employed as primary and/or secondary prophylaxis. On the other hand, disease-related bleeding complications (i.e., from esophageal varices) are common in patients with MPN. This analysis was performed to define the frequency of such events, identify risk factors, and assess antiplatelet/anticoagulant therapy in a cohort of patients with MPN.

Concepts: Thrombosis, Actuarial science, Warfarin, Esophageal varices, Anticoagulant, Myeloproliferative disease, Myelofibrosis, Essential thrombocytosis


Myeloproliferative neoplasms (MPNs) are chronic blood disorders caused by clonal expansion in one or more myeloid lineages and include essential thrombocythemia (ET), polycythemia vera (PV), primary myelofibrosis (PMF) and chronic myeloid leukemia (CML). Cardiovascular events are a main challenge for patients with MPN and can lead to their death.

Concepts: Blood, Hematology, Leukemia, Blood disorders, Chronic myelogenous leukemia, Myeloproliferative disease, Myelofibrosis, Essential thrombocytosis


Little is known about the outcomes of Philadelphia-negative myeloproliferative neoplasms (MPNs) in adolescents and young adults (AYA). We reviewed all patients with essential thrombocythemia (ET), polycythemia vera (PV), and myelofibrosis (MF) treated at our institution from 1988 to 2016 who were aged 16 to 39 years (AYA) and described their outcomes in comparison to older MPN population. Of 2206 patients, 185 (8.3%) were identified as AYA: 105 (57%) ET, 43 (23%) PV, and 37 (20%) MF. The median age was 33 years [range, 16-39], and median follow-up time 3 years [range, 0.04-25]. JAK2 allele burdens were significantly lower among AYA JAK2V617F-mutated patients in both PV (p = 0.001) and MF (p = 0.005). Seven percent of MPN AYA patients were diagnosed with a thrombotic event at, or prior to, diagnosis. Over the short median follow-up, 4 thrombotic (PV = 1, MF = 3) and 3 leukemia (ET = 2, MF = 1) events occurred. In multivariate analysis, AYA did not predict for thrombotic or transformational events across three cohorts. In the MF cohort, there was a reduced frequency of negative prognostic variables of anemia (p = 0.011) and leukocytosis (p = 0.048) in AYA when compared with non-AYA. Overall survival was significantly superior in the AYA cohorts in all three MPN groups, namely MF (p < 0.001), PV (p < 0.001), and ET (p = 0.002). Our findings suggest that MPN AYA patients exhibit an indolent clinical phenotype characterized by favorable survival outcomes.

Concepts: Population, Multivariate statistics, Hematology, Myeloproliferative disease, Myelofibrosis, Essential thrombocytosis


The prognosis of myeloproliferative neoplasms (MPN), including primary myelofibrosis (PMF), polycythemia vera (PV; post-PV MF) and essential thrombocythemia (ET; post-EMF) varies considerably, between these disorders as well as within each diagnosis. Molecular studies have identified “driver mutations”, in JAK2, MPL1 and CALR, and additional somatic DNA mutations, including ASXL1, EZH2, IDH1/2 and SRSF2, that affect prognosis differentially. Patients with mutations in CALR (type1) have a better outlook than patients with mutations in JAK2 or MPL, while patients without any of the driver mutations (triple negative) have the shortest life expectancy. Mutations in ASXL1, EZH2 and SRSF2 may be associated with shortened survival, and IDH mutations carry a higher risk of leukemic transformation. The combination and number of mutations are more important than a given single mutation. Mutations also appear to impact the outcome of hematopoietic cell transplantation (HCT), currently the only treatment with curative potential. Based on available data, the best post-HCT outcome is observed with CALR mutations. Triple negativity has a negative impact. The data on JAK2 are controversial. Mutations in ASXL1 or IDH1/2 reduce the probability of progression-free survival after HCT, although the impact of ASXL1 differs between patients with primary and secondary MF. While it is not clear to what extent HCT can overcome the risks associated with a given mutational pattern, at present, early HCT should be considered in triple negative patients and patients with PMF who harbor mutations in ASXL1. Mutations in EZH2, SRSF2 or IDH, particularly if combined with other mutations, should also lead to consideration of HCT. Further studies are needed to validate the present observations and determine the impact of additional mutations that have been identified.

Concepts: DNA, Genetics, Cancer, Mutation, DNA repair, Myeloproliferative disease, Myelofibrosis, Essential thrombocytosis


The classical BCR-ABL1-negative myeloproliferative neoplasms (MPN) include primary myelofibrosis (PMF), polycythaemia vera (PV) and essential thrombocythaemia (ET). They are characterized by stem cell-derived clonal proliferation, harbour Janus kinase 2 (JAK2), or calreticulin (CALR), or myeloproliferative leukaemia virus oncogene (MPL) driver mutations and exert an over activated JAK-signal transducer and activator of transcription (STAT) pathway. Therefore JAK inhibiting strategies have been successfully investigated in MPN clinical trials. Areas Covered: The present review aims to provide a concise overview of the current and future role of JAK inhibitors in the therapeutic armamentarium of MPN. Expert opinion: The JAK1/JAK2 inhibitor ruxolitinib has clearly enriched the therapeutic armamentarium of MPN and is now licenced for more than five years in MF and over three years as second line in PV. Momelotinib, although of limited activity in MPN trials, demonstrated unique property of improving MF associated anaemia. Less myelosuppressive or more selective JAK inhibitors like pacritinib, NS-01872 or Itacitinib are new promising agents tested in MF. JAK inhibition has become a cornerstone of MPN therapy and future efforts focus on ruxolitinib-based combinations and new JAK inhibitors.

Concepts: Signal transduction, Transcription factor, Hematology, Inhibitor, Xanthine oxidase inhibitor, Myeloproliferative disease, Myelofibrosis, Essential thrombocytosis