Mutations and long-term outcome of 217 young patients with essential thrombocythemia or early primary myelofibrosis

Clinical Features and Long-Term Outcomes of a Pan-Canadian Cohort of Adolescents and Young Adults with Myeloproliferative Neoplasms: A Canadian MPN Group Study

Myeloproliferative neoplasms (MPNs) are a group of chronic hematologic malignancies that lead to morbidity and early mortality due to thrombotic complications and progression to acute leukemia. Clinical and mutational risk factors have been demonstrated to predict outcomes in patients with MPNs and are used commonly to guide therapeutic decisions, including allogenic stem cell transplant, in myelofibrosis. Adolescents and young adults (AYA, age ≤45 years) comprise less than 10% of all MPN patients and have unique clinical and therapeutic considerations. The prevalence and clinical impact of somatic mutations implicated in myeloid disease has not been extensively examined in this population. We conducted a retrospective review of patients evaluated at eight Canadian centers for MPN patients diagnosed at ≤45 years of age. In total, 609 patients were included in the study, with median overall survival of 36.8 years. Diagnosis of prefibrotic or overt PMF is associated with the lowest OS and highest risk of AP/BP transformation. Thrombotic complications (24%), including splanchnic circulation thrombosis (9%), were frequent in the cohort. Mutations in addition to those in JAK2/MPL/CALR are uncommon in the initial disease phase in our AYA population (12%); but our data indicate they may be predictive of transformation to post-ET/PV myelofibrosis.

SOHO State of the Art Updates and Next Questions | Diagnosis, Outcomes, and Management of Prefibrotic Myelofibrosis

Prefibrotic primary myelofibrosis (prefibrotic PMF) is a myeloproliferative neoplasm with distinct characteristics comprising histopathological and clinico-biological parameters. It is classified as a subtype of primary myelofibrosis. In clinical practice, it is essential to correctly distinguish prefibrotic PMF from essential thrombocythemia especially but also overt PMF besides other myeloid neoplasms. Risk stratification and survival outcomes for prefibrotic PMF are worse than that of ET but better than that of overt PMF. Rates of progression to overt PMF and blast phase disease are also higher for prefibrotic PMF than ET. In this review we first discuss the historical context to the evolution of prefibrotic PMF as an entity, its presenting features and diagnostic criteria. We emphasize the differences between prefibrotic PMF, ET, and overt PMF with regards to presenting features and disease outcomes including thrombohemorrhagic events and progression to fibrotic and blast phase disease. Next, we discuss the risk stratification models and contextualize these in the setting of clinical management. We share our view of personalizing treatment to address unique patient needs in the context of currently available management options. Lastly, we discuss areas of critical need in clinical research and speculate on the possibility of future disease course modifying therapies in prefibrotic PMF.

Young patients with myelofibrosis have distinct clinicomolecular features, favorable prognosis, and commonly exhibit inflammatory comorbidities

Myelofibrosis (MF) is commonly diagnosed in older individuals and has not been extensively studied in young patients. Given the infrequent diagnosis in young patients, analyzing this cohort may identify factors that predict for disease development/progression. We retrospectively analyzed clinical/genomic characteristics, treatments, and outcomes of patients with MF aged 18-50 years (YOUNG) at diagnosis. Sixty-three YOUNG patients were compared to 663 patients diagnosed at 51 or older (OLDER). YOUNG patients were more likely to be female, harbor driving CALR mutations, lack splicing gene mutations, and have low-risk disease by dynamic international prognostic scoring system (DIPSS) at presentation. Thirty-six patients (60%) presented with incidental lab findings and 19 (32%) with symptomatic disease. Median time to first treatment was 9.4 months (mo). Fourteen (22%) YOUNG patients underwent allogeneic hematopoietic stem cell transplant (median 57.4 mo post-diagnosis). Five (8%) developed blast-phase disease (median 99 mo post-diagnosis). Median overall survival (OS) for YOUNG patients was not reached compared to 62.8 mo in OLDER cohort (p < 0.001). The survival advantage for YOUNG patients lost significance when compared to OLDER patients lacking splicing mutations (p = 0.11). Thirty-one (49%) had comorbidities predating MF diagnosis. Presence of a comorbidity correlated with increased disease risk as measured by serial DIPSS (p=0.02). Increased disease risk correlated with decreased OS (p = 0.05). MF is rare in young adults, has distinct clinical/molecular correlates, and a favorable prognosis. The high frequency of inflammatory comorbidities and their correlation with progression of disease risk clinically highlights the role of inflammation in MF pathogenesis.

Budd-Chiari syndrome in myeloproliferative neoplasms: A review of literature

Myeloproliferative neoplasms (MPNs) are defined as clonal disorders of the hematopoietic stem cell in which an exaggerated production of terminally differentiated myeloid cells occurs. Classical, Philadelphia-negative MPNs, i.e., polycythemia vera, essential thrombocythemia and primary myelofibrosis, exhibit a propensity towards the development of thrombotic complications that can occur in unusual sites, e.g., portal, splanchnic or hepatic veins, the placenta or cerebral sinuses. The pathogenesis of thrombotic events in MPNs is complex and requires an intricate mechanism involving endothelial injury, stasis, elevated leukocyte adhesion, integrins, neutrophil extracellular traps, somatic mutations (e.g., the V617F point mutation in the JAK2 gene), microparticles, circulating endothelial cells, and other factors, to name a few. Herein, we review the available data on Budd-Chiari syndrome in Philadelphia-negative MPNs, with a particular focus on its epidemiology, pathogenesis, histopathology, risk factors, classification, clinical presentation, diagnosis, and management.

Essential Thrombocythemia and Post-Essential Thrombocythemia Myelofibrosis: Updates on Diagnosis, Clinical Aspects, and Management

Although several decades have passed since the description of myeloproliferative neoplasms (MPN), many aspects of their pathophysiology have not been elucidated. In this review, we discuss the mutational landscape of patients with essential thrombocythemia (ET), prognostic scores and salient pathology, and clinical points. We discuss also the diagnostic challenges of differentiating ET from prefibrotic MF. We then focus on post-essential thrombocythemia myelofibrosis (post-ET MF), a rare subset of MPN that is usually studied in conjunction with post-polycythemia vera MF. The transition of ET to post-ET MF is not well studied on a molecular level, and we present available data. Patients with secondary MF could benefit from allogenic hematopoietic stem cell transplantation, and we present available data focusing on post-ET MF.

Essential Thrombocythemia: One-Center Data in a Changing Disease

Introduction: Essential thrombocythemia is a chronic myeloproliferative neoplasm associated with thrombo-hemorrhagic events and the progression to myelofibrosis or acute myeloid leukemia. The purpose of this article is to present real-world data on ET cases diagnosed and managed between 1998 and 2020 in the largest, tertiary hematology reference center in Romania and to evaluate the impact of thrombotic events on survival. Methods: A real-world, retrospective cohort-type study was conducted. We collected and statistically analyzed data from 168 patients who met the 2016 WHO diagnostic criteria for ET and who were managed between 1998 and 2020 in our center. Results: The median age at diagnosis of ET was 51.8 years, with a female predominance (66.07%). The JAK2V617F mutation was detected in 60.71% of patients. Leukocytosis at diagnosis was associated with a higher risk of thrombosis, and JAK2V617F-positive cases exhibited a 1.5-fold higher risk of developing thrombotic events. The average survival in ET with major thrombosis was 14.5 years versus 20.6 years in ET cases without major thrombosis. Other predictors of survival were high-risk IPSET score and age >60 years. Conclusions: Romanian patients diagnosed with ET are generally younger than 60 years and are predominantly female. The occurrence of thrombotic events was influenced by gender, leukocyte count at diagnosis and JAK2V617F positivity. Survival was impacted by age, the presence of JAK2V617F mutation, hypertension, major thrombotic complications and IPSET score. Notably, these findings warrant careful interpretation and further confirmation in the setting of prospective studies.

Clinical features and next-generation sequencing landscape of essential thrombocythemia, prefibrotic primary myelofibrosis, and overt fibrotic primary myelofibrosis: a Chinese monocentric retrospective study

OBJECTIVE

Since prefibrotic primary myelofibrosis (pre-PMF) was recognized as a separate entity in the 2016 revised classification of MPN differed from essential thrombocythemia (ET) or overt fibrotic primary myelofibrosis (overt PMF), it has been a subject of debate among experts due to its indefinite diagnosis.

METHODS

We retrospectively reviewed the clinical parameters, haematologic information, and genetic mutations of patients who were diagnosed with myeloproliferative neoplasms (MPNs) according to the WHO 2016 criteria in China, including 56 ET patients, 19 pre-PMF patients, and 43 overt PMF patients.

RESULTS

Pre-PMF patients exhibited higher leukocyte counts [14.2(6.0-28.1) × 10⁹/L vs 9.6(4.0-55.0) × 10⁹/L, P = 0.003], LDH values [307(233-479)U/L vs 241(129-1182)U/L, P < 0.001], onset ages [67(32-76) years vs 50(16-79) years, P = 0.006], a higher frequency of splenomegaly(47.4% vs 16.7%, P = 0.018) and hypertension (57.9 vs 23.2%, P = 0.005) than ET patients. On the other hand, pre-PMF patients had higher platelet counts [960(500-2245) × 10⁹/L vs 633(102-1720) × 10⁹/L, P = 0.017], haemoglobin levels [152(115-174)g/L vs 119(71-200)g/L, P = 0.003], lower LDH values [307(233-479)U/L vs 439(134-8100)U/L, P = 0.007] and a lower frequency of splenomegaly(47.4 vs 75.6%, P = 0.031) than overt PMF patients. Next-generation sequencing landscape was performed in 50 patients, revealed the frequency of EP300 mutations was significantly increased in pre-PMF patients compared with ET and overt PMF patients (60 vs 10 vs 15.79%, P = 0.033), and WT1 was more often overexpressed (WT1/ABL1 copies ≥ 1.0%) in patients with overt PMF than in those with ET or pre-PMF(54.55 vs 16.67 vs 17.65%, P = 0.009). In terms of outcome, male sex, along with symptoms including MPN10, anaemia (haemoglobin < 120 g/L), thrombocytopenia (platelet count < 100 × 10⁹/L), leucocytosis (leukocyte counts > 13 × 10⁹/L), high LDH value (> 350U/L), splenomegaly, WT1 overexpression(WT1/ABL1 copies ≥ 1.0%), KMT2A, ASXL1 and TP53 mutations, indicated a poor prognosis for PMF patients.

CONCLUSION

The results of this study indicated that a comprehensive evaluation of BM features, clinical phenotypes, haematologic parameters, and molecular profiles is needed for the accurate diagnosis and treatment of ET, pre-PMF, and overt PMF patients.

Low-risk polycythemia vera and essential thrombocythemia: management considerations and future directions

Thrombotic events are a distinctive feature of the myeloproliferative neoplasms (MPNs) polycythemia vera (PV) and essential thrombocythemia (ET). Patients with these MPNs may also experience a poor quality of life secondary to symptom burden, as well as progression of disease to acute leukemia or myelofibrosis. Over the years, various risk stratification methods have evolved in order to attempt to predict thrombotic risk, which is the largest contributor of morbidity and mortality in these patients. More than half of PV and ET patients are low- or intermediate-risk disease status at the time of diagnosis. While therapeutic development is presently focused on high-risk patients, there is a paucity of therapies, outside of aspirin and therapeutic phlebotomy, which can reduce the thrombotic risk or delay disease progression in low-risk patients. In this review, we first describe the various complications that patients with PV and ET experience, and then detail our evolving understanding of risk stratification in these diseases. We then highlight the available evidence on the management of low-risk PV and ET and include a description of novel therapies currently under investigation in this space. We conclude with recommendations for future directions to advance our understanding and improve the treatment of low-risk PV and ET.

Essential Thrombocythemia in Children and Adolescents

Simple Summary

Among chronic Ph-negative myeloproliferative neoplasms, essential thrombocythemia is found in children with low but increasing incidence. The diagnostic and clinical features do not completely overlap with ET of adult age. A significant number of cases, in fact, do not meet the criteria of clonality, and many cases require extensive clinical evaluation to exclude secondary, reactive forms. Therefore, histological analysis of bone marrow biopsy is necessary, and its use should be enforced. The clinical course appears to be more benign, at least within the first decades of observation, with the incidence of thrombotic events being much lower than in adults (4 % vs. 30%). Hemorrhages are mostly irrelevant. Therefore, the management should be carefully adapted to the individual patient, balancing the risk of future complications with long-term collateral effects of any drug. This review analyzes the peculiarities of the disease facing similarities and differences with adult scenarios.

Abstract

This paper reviews the features of pediatric essential thrombocythemia (ET). ET is a rare disease in children, challenging pediatric and adult hematologists alike. The current WHO classification acknowledges classical Philadelphia-negative MPNs and defines diagnostic criteria, mainly encompassing adult cases. The presence of one of three driver mutations (JAK2V617F, CALR, and MPL mutations) represent the proof of clonality typical of ET. Pediatric ET cases are thus usually confronted by adult approaches. These can fit only some patients, because only 25–40% of cases present one of the driver mutations. The diagnosis of hereditary, familial thrombocytosis and the exclusion of reactive/secondary thrombocytosis must be part of the diagnostic process in children and can clarify most of the negative cases. Still, many children present a clinical, histological picture of ET, with a molecular triple wild-type status. Moreover, prognosis seems more benign, at least within the first few decades of follow-up. Thrombotic events are rare, and only minor hemorrhages are ordinarily observed. As per the management, the need to control symptoms must be balanced with the collateral effects of lifelong drug therapy. We conclude that these differences concert a compelling case for a very careful therapeutic approach and advocate for the importance of further cooperative studies.

Philadelphia chromosome-negative myeloproliferative neoplasms in younger adults: A critical discussion of unmet medical needs, with a focus on pregnancy

Myeloproliferative neoplasms (MPN) are traditionally regarded as a disease of older adults, though a not negligible fraction of cases occurs at a younger age, including women of childbearing potential. MPN in younger patients, indeed, offer several challenges for the clinical hematologist, that goes from difficulties in reaching a timely and accurate diagnosis to a peculiar thrombotic risk, with a relatively high incidence of thromboses in unusual sites (as the splanchnic veins or the cerebral ones). Moreover, the issue of pregnancy is recently gaining more attention as maternal age is rising and molecular screening are widely implemented, leading to a better recognition of these cases, both before and during pregnancy. In the present work we aim at discussing four clinical topic that we identified as areas of uncertainty or true unmet medical needs in the management of younger patients with MPN, with a particular focus on the topic of pregnancy. For each of these topics, we critically reviewed the available evidence that support treatment decisions, though acknowledging that recommendations in this field are mostly based on expert opinion or derived from guidelines of other clinical conditions that share with MPN a high vascular risk, as antiphospholipid syndrome. Taking into consideration both the lack of evidence-based data and the clinical heterogeneity of MPN, we support an individualized strategy of counseling and management for both young patients and for expectant mother with MPN.

Unmet clinical needs in the management of CALR-mutated essential thrombocythaemia: a consensus-based proposal from the European LeukemiaNet

Recommendations regarding management of essential thrombocythaemia rely on studies done before the discovery of the CALR mutation. On May 20, 2020, the European LeukemiaNet annual meeting was held with the goal to identify unmet clinical needs in myeloproliferative neoplasms. Because patients with a CALR mutation have specific clinical characteristics, treatment of CALR-mutated essential thrombocythaemia was considered an unmet clinical need by the European LeukemiaNet. The elaboration of a consensus document with recommendations according to current evidence was proposed as a solution for resolving uncertainties in the treatment of CALR-mutated essential thrombocythaemia. A steering committee comprising four European LeukemiaNet members was then formed and a panel of ten experts in the field was recruited. The experts proposed 51 potential unmet clinical needs in the management of CALR-mutated essential thrombocythaemia and were asked to score the relevance of each topic. Those topics that obtained the highest scores as relevant unmet clinical needs were identified, including antiplatelet therapy in patients at low risk, definition of extreme thrombocytosis and its management in patients at low risk, indications of cytoreduction and targets of therapy, first-line treatment of choice in young patients (<60 years), and management of pregnancy. After the steering committee revised the available evidence for each topic, a consensus on management and proposal for improving knowledge was achieved by use of an email-based, two round, Delphi approach. Consensus was achieved when 90% of the panellists agreed with a statement and included 14 recommendations and six solution proposals. Key recommendations included careful observation for asymptomatic patients with classical, low-risk, CALR-mutated essential thrombocythaemia without cardiovascular risk factors; caution in the use of antiplatelet therapy for symptomatic patients at low risk with platelet counts of 1000-1500 × 109 platelets per L, in such cases cytoreduction is an adequate option, especially if adquired Von Willebrand disease is present; cytoreduction is recommended for extreme thrombocytosis (platelet count >1500 × 109 platelets per L) with pegylated interferon alfa being the preferred option for younger patients; both hydroxycarbamide and anagrelide might be given to patients ineligible for pegylated interferon alfa; and treatment algorithms for patients with high-risk pregnancies should not be changed according to genotype. The European LeukemiaNet proposes to use these recommendations in the routine management of patients with CALR-mutated essential thrombocythaemia, and designing new clinical studies in this field might be useful.

Comparison of the effects between MPL and JAK2V617F on thrombosis and peripheral blood cell counts in patients with essential thrombocythemia: a meta-analysis

To assess the effects between MPL and JAK2V617F on the thrombosis risk and peripheral blood cell counts in patients with essential thrombocythemia (ET), we identified eligible studies from PubMed, Embase, and the Cochrane Library. Seven studies were ultimately included in this meta-analysis. All studies reported the peripheral blood cell counts of ET patients, and three of them reported the eligible thrombotic events. In comparing the effect of MPL versus JAK2V617F on thrombosis, 1257 ET patients (73 MPL + and 1184 JAK2V617F +) were included. MPL-positive (MPL +) ET patients had a higher risk of thrombosis than JAK2V617F-positive (JAK2V617F +) ET patients [RR = 1.80 (1.08-3.01), P = 0.025]. And 3453 ET patients (138 MPL + and 3315 JAK2V617F +) were included in the comparison of peripheral blood cell counts. Platelet counts of MPL + ET patients were higher than that of JAK2V617F + ET patients [WMD = 81.18 (31.77-130.60), P = 0.001]. MPL + ET patients had lower hemoglobin [WMD =  - 11.66 (- 14.32 to - 9.00), P = 0.000] and white blood cell counts [WMD =  - 1.01 (- 1.47 to - 0.56), P = 0.000] than JAK2V617F + ET patients. These findings indicate that the MPL mutation is a high-risk factor for thrombosis in ET patients, and it may be rational to include MPL mutation in the revised IPSET as a criterion for thrombosis prediction scores. And given the differences in peripheral blood, it is necessary to further study whether MPL + ET patients differ from JAK2V617F + ET patients in bleeding and survival.

Calreticulin mutations in myeloproliferative neoplasms

Calreticulin (CALR) is a chaperone present in the endoplasmic reticulum, which is involved in the quality control of N-glycosylated proteins and storage of calcium ions. In 2013, the C-terminal mutation in CALR was identified in half of the patients with essential thrombocythemia and primary myelofibrosis who did not have a JAK2 or MPL mutation. The results of 8 years of intensive research are changing the clinical practice associated with treating myeloproliferative neoplasms (MPNs). The presence or absence of CALR mutations and their mutation types already provide important information for diagnosis and treatment decision making. In addition, the interaction with the thrombopoietin receptor MPL, which is the main mechanism of transformation by CALR mutation, and the expression of the mutant protein on the cell surface have a great potential as targets for molecular-targeted drugs and immunotherapy. This chapter presents recent findings on the clinical significance of the CALR mutation and the molecular basis by which this mutation drives MPNs.

CALR-ETdb, the database of calreticulin variants diversity in essential thrombocythemia

Essential thrombocythemia (ET) is a blood cancer defined by a strong increase of platelet numbers. A quarter of patients suffering from ET show mutations in the last exon of calreticulin (CALR) gene. Two variants named type 1 and type 2 represent 85% of these patients. However, a large number of other variants have been determined. In this study, we have compiled variants taken from COSMIC database and literature leading to 155 different variants. This large number of variants allowed redefining 5 new classes extending the classification of type 1-like and type 2-like to a finer description. These analyses showed that last class, named E, corresponding to more than 10% of CALR variants seemed not attached to ET. Structural properties analyzed showed that CALR variants associated to ET have common features. All the compiled and refined information had been included into a freely dedicated database CALR-ETdb (https://www.dsimb.inserm.fr/CALR-ET).

Clinical Characteristics and Management of Cerebral Venous Sinus Thrombosis in Patients with Essential Thrombocythemia

BACKGROUND AND OBJECTIVE

Essential thrombocythemia (ET) is a rare cause of cerebral venous sinus thrombosis (CVST). Analysis of the risk factors and treatment therapies of CVST in ET has yielded controversial findings.

SUBJECTS AND METHODS

We retrospectively investigated the clinical characteristics of CVST events in ET and compared baseline characteristics, causative factors, hematological effects, and treatments between ET patients with and without CVST.

RESULTS

Overall, 91 of 115 patients who met the ET diagnosis were included in this study. Among them, 23 (25.27%) patients met the diagnostic criteria of ET with CVST for inclusion, 14 (60.87%) of whom were females, with a median age of 34 (range 25-50). CVST diagnosis was made concomitantly to ET in 19 patients (82.61%). The most common symptom and sites of thrombosis of CVST was an acute or subacute headache and sigmoid sinuses, respectively. Compared with ET patients without CVST, ET patients with CVST were significantly younger (37.65±14.45 vs 60.93±13.46, P<0.001) and had lower prevalence of hypertension (4.34 vs 32.35%, P=0.003) and coronary artery disease (0 vs 14.71%, P = 0.045). Patients with CVST presented with significant lower platelet count (510.39±176.71 vs 750.82±249.10, P< 0.001) and higher score of IPSET-thrombosis (P=0.017). Multivariate logistic regression analysis indicated that age (P=0.002, OR 1.096, 95% CI 1.035-1.161), at least one CVRF (P = 0.024, OR 0.037, 95% CI 0.002-0.649), platelet count (P=0.045, OR 0.994, 95% CI 0.989-1.001), and lower percentage of antiplatelet therapy (P=0.035, OR 0.307, 95% CI 0.001-1.280) significantly contributed to the risk of CVST in ET.

CONCLUSION

Most patients (95.65%) had a favorable outcome without recurrence after standard anticoagulant and cytoreductive treatment at last follow-up. These findings indicate that CVST may be the initial presentation of ET, with its detection crucial for early diagnosis and appropriate management. Anticoagulant and cytoreductive therapies should be recommended for preventing ET-related CVST with JAK2 V617F mutation.

Primary myelofibrosis with concurrent CALR and MPL mutations: A case report

BACKGROUND

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm (MPN) characterized by recurrent mutations in the JAK2, CALR, and MPL genes. The CALR and MPL co-mutation is very rare. To our knowledge, no more than five cases have been reported. Here, we report a case of PMF in which a CALR and MPL co-mutation was detected by next-generation sequencing (NGS) technology, and a literature review was performed.

CASE SUMMARY

A 73-year-old woman was admitted to our hospital in 2018 due to abdominal distension. The patient had splenomegaly, lymphadenopathy, leukopenia, anemia, and immature granulocytes in peripheral blood. There were dacrocytes and atypical megakaryocytes in bone marrow, and megakaryocytic proliferation was very active, accompanied by reticulin fibrosis grade 2. By NGS analysis of the bone marrow sample, we detected mutations in CALR, MPL, and PIK3RI, while JAK2 V617F and BCR-ABL were negative. Therefore, the patient was diagnosed with PMF and received oral ruxolitinib. However, the spleen and hematologic responses were poor. We review the literature, analyze previous reports of the mutation sites in our patient and differences between our patient and other reported cases of co-mutated CALR and MPL genes, and discuss the reason why the CALR and MPL co-mutations are rare and possible mechanisms and their impact on the prognosis of patients.

CONCLUSION

CALR and MPL mutations can be concurrent in MPN, but they are rare. The use of NGS may help to identify more patients with co-mutated CALR and MPL genes. This will help to further explore the mechanism and its impact on these patients to develop appropriate treatment strategies.

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

Risk factors for progression to blast phase and outcome in 589 patients with myelofibrosis treated with ruxolitinib: Real-world data

The impact of ruxolitinib therapy on evolution to blast phase (BP) in patients with myelofibrosis (MF) is still uncertain. In 589 MF patients treated with ruxolitinib, we investigated incidence and risk factors for BP and we described outcome according to disease characteristics and treatment strategy. After a median follow-up from ruxolitinib start of 3 years (range 0.1-7.6), 65 (11%) patients transformed to BP during (93.8%) or after treatment. BP incidence rate was 3.7 per 100 patient-years, comparably in primary and secondary MF (PMF/SMF) but significantly lower in intermediate-1 risk patients (2.3 vs 5.6 per 100 patient-years in intermediate-2/high-risk patients, P < .001). In PMF and SMF cohorts, previous interferon therapy seemed to correlate with a lower probability of BP (HR 0.13, P = .001 and HR 0.22, P = .02, respectively). In SMF, also platelet count <150 × 10⁹ /l (HR 2.4, P = .03) and peripheral blasts ≥3% (HR 3.3, P = .004) were significantly associated with higher risk of BP. High-risk category according to dynamic International Prognostic Score System (DIPSS) and myelofibrosis secondary to PV and ET Collaboration Prognostic Model (MYSEC-PM predicted BP in patients with PMF and SMF, respectively. Median survival after BP was 0.2 (95% CI: 0.1-0.3) years. Therapy for BP included hypomethylating agents (12.3%), induction chemotherapy (9.2%), allogeneic transplant (6.2%) or supportive care (72.3%). Patients treated with supportive therapy had a median survival of 6 weeks, while 73% of the few transplanted patients were alive at a median follow-up of 2 years. Progression to BP occurs in a significant fraction of ruxolitinib-treated patients and is associated with DIPSS and MYSEC-PM risk in PMF and SMF, respectively.

Myeloproliferative Neoplasms in Children, Adolescents, and Young Adults

PURPOSE OF REVIEW

Myeloproliferative neoplasms are traditionally seen in older adults, making them poorly understood in younger patients. Clinical presentation, genetic landscape, outcomes, and best management practices are inadequately described in this group. Over the past decade, more research has focused on younger patients, and this paper seeks to review and describe the current status of the field.

RECENT FINDINGS

A recent review analyzed the available pediatric MPN literature and highlighted the paucity of published data. Pediatric patients showed lower rates of the common mutations found in adults, thrombotic events, and disease transformation to myelofibrosis and acute leukemia. A number of centers have recently shared their experience with young adult patients. Better survival outcomes were confirmed for young adult patients compared to older patients. There is still much to learn about myeloproliferative neoplasms in pediatric and young adult patients, but currently available data showing better outcomes is reassuring.

Thrombophilic Risk of Factor V Leiden, Prothrombin G20210A, MTHFR, and Calreticulin Mutations in Essential Thrombocythemia Egyptian Patients

Objectives

Essential thrombocythemia (ET) is one of the myeloproliferative neoplasms characterized by a sustained elevation of platelet numbers with a tendency for thrombosis and hemorrhage. The aim of this work is to establish the relation between calreticulin, factor V Leiden, prothrombin G20210A, and MTHFR mutations in ET patients and the thrombotic risk of these patients.

Methods

This study was carried out on 120 ET patients and 40 apparently healthy individuals as a control group.

Results

There were increases in WBCs, PLT counts, PT, fibrinogen concentration factor V Leiden, and MTHFR mutation in ET patients as compared to the control group (P < 0.05). Also, there were increases in WBCs, PLT counts, and hematocrit value in thrombosed ET patients as compared to the nonthrombosed ones (P < 0.05). On the contrary, there was no significantly statistical difference in ET patients with JAK2 V617F positive mutation versus the JAK2 negative group (P > 0.05) and in patients with cardiovascular risk factors versus patients with noncardiovascular risk factors (P > 0.05). ET patients with factor V Leiden, prothrombin gene, and CALR mutations were more prone to thrombosis (odds ratio 5.6, 5.7 and 4.7, respectively). On the contrary, JAk2V 617F and MTHFR mutations have no effect on the thrombotic state of those patients.

Conclusion

There is a significant increase risk of thrombosis in ET patients with CALR mutation, thrombophilic mutations, as well as factor V Leiden and prothrombin gene mutation with a risk of developing leukemic transformation.

Impact of 2016 WHO diagnosis of early and overt primary myelofibrosis on presentation and outcome of 232 patients treated with ruxolitinib

The 2016 WHO criteria identified early primary myelofibrosis (PMF) as an individual entity with milder clinical features and better outcome compared with overt PMF. Here, we compared early and overt PMF patients treated with ruxolitinib in terms of baseline clinical/laboratory characteristics, response, and toxicity to treatment. We observed that early-PMF patients achieve better and more stable spleen and symptoms responses, with significantly lower rates of hematological toxicities. No differences in overall and leukemia-free survival were detected between the two cohorts. The application of 2016 WHO criteria is crucial to identify those PMF patients who deserve a stricter monitoring during treatment.

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

OBJECTIVE

Prefibrotic/early primary myelofibrosis (pre-PMF) and essential thrombocythemia (ET) exhibited different features of bone marrow; however, this is not always easy to judge objectively, making pathologists' distinction often suboptimal. In the WHO 2008 criteria, pre-PMF was not defined as a subgroup of PMF; therefore, affected patients were at a higher risk of misdiagnosis with ET. In this study, we examined the prevalence of pre-PMF patients among those previously diagnosed with ET in Japan.

METHOD

We reviewed bone marrow specimens and clinical and molecular parameters of patients who were previously diagnosed with ET by the WHO 2008 criteria.

RESULTS

Among 107 ET patients, 13 patients were redefined as having pre-PMF. Pre-PMF patients exhibited a higher frequency of MPL mutation and increased platelet counts compared to true ET patients. Molecular analysis revealed the frequencies of high-risk molecular mutations, such as ASXL1, EZH2, and SRSF2, were significantly increased in pre-PMF patients than those in true ET patients.

CONCLUSION

These results demonstrated the value of reexamining clinical records for patients diagnosed with ET by the WHO 2008 criteria and emphasized that adequate examinations of patients' bone marrow are crucial for an accurate diagnosis of pre-PMF and ET.

Developments in diagnosis and treatment of essential thrombocythemia

INTRODUCTION

Essential thrombocythemia (ET) is a chronic myeloproliferative neoplasm characterized by thrombocytosis, increased risk of thrombotic/hemorrhagic events and clonal evolution into blast phase or myelofibrosis. Areas covered: The authors will discuss biology, diagnosis, prognosis, therapy, and outcome of ET. An accurate molecular-morphologic assessment is necessary in order to properly establish diagnosis and prognosis of ET. Stratification for thrombosis prediction is essential, and IPSET-t model is widely applied. The current treatment strategy is directed to lower the rate of vascular events using cytoreduction in patients at high risk. Prophylactic low dose aspirin indication is more uncertain. To date, therapies for patients who are resistant or intolerant to first-line treatments are scarce. Overall, life expectancy indicates an indolent disease, but IPSET model helps in predicting survival at the time of diagnosis. Expert opinion: Challenging for the future will be to share criteria for ET diagnosis with the community. New insights into the molecular pathogenesis of the disease will improve the prediction of clonal evolution and outcome, and lead to the use of disease-modifying treatments.

[Allogeneic hematopoietic stem cell transplantation for the treatment of acute myeloid leukemia with primary thrombocytosis: three cases report and literatures review]

目的

探讨原发性血小板增多症（ET）转化急性髓系白血病（AML）的病情变化特点及异基因造血干细胞移植（allo-HSCT）的治疗价值。

方法

回顾性分析3例ET转AML患者的临床特征、实验室检查结果及诊治经过，复习相关文献。

结果

例1，男，44岁，初诊ET时PLT 500×10⁹/L，3年后疾病转变为骨髓增生异常综合征时WT1基因由初诊时77拷贝/10 000 ABL拷贝升至13 171拷贝/10 000 ABL拷贝，染色体核型发生异常改变，在地西他滨治疗过程中快速进展为AML。例2，男，58岁，诊断ET时PLT 2 100×10⁹/L，9年后疾病进展为AML，WT1基因由初诊时130拷贝/10 000 ABL拷贝升至3 222拷贝/10 000 ABL拷贝，在化疗期间短期内复发。例3，男，60岁，初诊ET时PLT 900×10⁹/L，5年后疾病转化为AML，WT1基因由初诊时56拷贝/10 000 ABL拷贝升至3 696拷贝/10 000 ABL拷贝，化疗期间出现中枢神经系统侵犯。例1移植前未缓解，例2缓解后短期内复发，例3出现髓外侵犯。3例患者均顺利完成allo-HSCT，移植后骨髓缓解，染色体核型正常，例3中枢神经系统病灶消失，JAK2基因突变均转阴，WT1基因表达均<200拷贝/10 000 ABL拷贝，未发生严重并发症。

结论

ET转化的AML病情凶险，allo-HSCT是目前唯一可能治愈此疾病的方法。

Characteristics and outcomes of patients with essential thrombocythemia or polycythemia vera diagnosed before 20 years of age: a systematic review

Although it is well known that myeloproliferative neoplasms occur in younger patients, few large cohorts of such patients have been reported. Thus, our knowledge about circumstances of diagnosis, outcome and treatment is limited, especially for children and young adults. We therefore performed a systematic review of cases, published since 2005, concerning patients aged below 20 years at the time of diagnosis of essential thrombocythemia or polycythemia vera. We identified 396 cases of essential thrombocythemia and 75 of polycythemia vera. The median age at diagnosis was 9.3 and 12 years, respectively, and females constituted 57.6% and 45% of the groups, respectively. Half of the patients were asymptomatic at diagnosis. The proportion of so-called triple negativity was high: 57% in essential thrombocythemia and 73% in polycythemia vera. The incidence of thrombosis during the follow-up was 9.3% in patients with polycythemia vera and less, 3.8%, in those with essential thrombocythemia. Venous events were predominant (84.2%), with hemorrhagic episodes being rarer (<5%). The risk of evolution also seemed low (2% to myelofibrosis and no reports of acute leukemia), but the median follow-up was only 50 months. Survival curves were not available. Half of the patients received an antithrombotic drug and 40.5% received a cytoreductive drug. All data should be analyzed with care because of the proportion of missing data (10.7% to 74.7%). This review highlights interesting points concerning this population of young patients with myeloproliferative neoplasms, including that such patients were identified as negative for all common driver mutations, but also shows the need for larger contemporary cohorts with longer follow-up to assess the true prognosis of these patients.

Unfolding the Role of Calreticulin in Myeloproliferative Neoplasm Pathogenesis

In 2013, two seminal studies identified gain-of-function mutations in the Calreticulin (CALR) gene in a subset of JAK2/MPL-negative myeloproliferative neoplasm (MPN) patients. CALR is an endoplasmic reticulum (ER) chaperone protein that normally binds misfolded proteins in the ER and prevents their export to the Golgi and had never previously been reported mutated in cancer or to be associated with hematologic disorders. Further investigation determined that mutated CALR is able to achieve oncogenic transformation primarily through constitutive activation of the MPL-JAK-STAT signaling axis. Here we review our current understanding of the role of CALR mutations in MPN pathogenesis and how these insights can lead to innovative therapeutics approaches.

Myeloproliferative neoplasms in the young: Mayo Clinic experience with 361 patients age 40 years or younger

Between 1967 and 2017, 361 patients with myeloproliferative neoplasms (MPN), age ≤ 40 years, were seen at our institution, constituting 12% of all MPN patients (n = 3023) seen during the same time period; disease-specific incidences were 12% in polycythemia vera (PV; n = 79), 20% in essential thrombocythemia (ET; n = 219) and 5% in primary myelofibrosis (PMF; n = 63). Compared to their older counterparts, younger patients were more likely to present with low risk disease (P < .001) and display female preponderance in ET (P = .04), lower incidence of arterial events overall (P < .001), and higher incidence of venous thrombosis in PV (P = .01). Younger patients were also more likely to express CALR mutations, in ET and PMF, normal karyotype, in PV and PMF, and lower incidence of high molecular risk mutations in PMF (P significant in all instances). Over median follow-up of 11.3, 13, and 7.1 years for PV, ET, and PMF, leukemic transformations were respectively documented in 4%, 2%, and 10% (P values 0.1-0.9) while incidences of fibrotic progression in PV (22%) and ET (16%) were expectedly higher in young patients, because of their longer survival (P < .001). Median survival in young patients was 37 years for PV, 35 for ET and 20 for PMF; the corresponding values were 22, 22, and 8 years for ages 41-60 years and 10, 11, and 3 years for ages >60 years (P < .001). Young MPN patients comprise a unique disease subset defined by an attenuated-risk cytogenetic and mutational backdrop and conspicuously longer survival compared to their older counterparts, which requires assertion during patient counseling.

GATA1 Expression in BCR/ABL1-negative Myeloproliferative Neoplasms

Background

This study aimed to determine GATA1 expression levels to better characterize subgroups in BCR/ABL1-negative myeloproliferative neoplasms (MPNs).

Methods

This study enrolled 49 patients diagnosed as having BCR/ABL1-negative MPN on the basis of the 2016 World Health Organization classification : nine polycythemia vera (PV), 17 essential thrombocythemia (ET), 12 prefibrotic primary myelofibrosis (prePMF), and 11 overt primary myelofibrosis (PMF). Relevant clinical and laboratory data were retrieved from the medical records. The molecular analysis of CALR and MPL mutations and quantification of JAK2 V617F allele burden were performed. GATA1 expression was assessed by an immunohistochemical assay on bone marrow biopsy. GATA1 expression was analyzed serially in 18 patients.

Results

GATA1 expression decreased significantly in PMF compared with that in other subtypes, while no statistical difference was identified between ET and prePMF. GATA1 expression did not differ according to the mutation profiles or the allele burden of JAK2 V617F, but it decreased significantly in patients with overt fibrosis or leukemic transformation.

Conclusions

Our results suggest that GATA1 expression is significantly low in PMF and decreases with progressive fibrosis and possibly with leukemic transformation, although our attempt to accurately distinguish between subgroups using GATA1 immunohistochemical approach did not achieve statistical significance. A large patient cohort with long term follow-up is required to evaluate the prognostic value of GATA1 expression.

Ruxolitinib in elderly patients with myelofibrosis: impact of age and genotype. A multicentre study on 291 elderly patients

Ruxolitinib is a JAK1/2 inhibitor that may control myelofibrosis (MF)-related splenomegaly and symptoms and can be prescribed regardless of age. While aging is known to correlate with worse prognosis, no specific analysis is available to confirm that ruxolitinib is suitable for use in older populations. A clinical database was created in 23 European Haematology Centres and retrospective data on 291 MF patients treated with ruxolitinib when aged ≥65 years were analysed in order to assess the impact of age and molecular genotype on responses, toxicities and survival. Additional mutations were evaluated by a next generation sequencing (NGS) approach in 69 patients with available peripheral blood samples at the start of ruxolitinib treatment. Compared to older (age 65-74 years) patients, elderly (≥75 years) showed comparable responses to ruxolitinib, but higher rates of drug-induced anaemia and thrombocytopenia and worse survival. Nonetheless, the ruxolitinib discontinuation rate was comparable in the two age groups. Number and types of molecular abnormalities were comparable across age groups. However, the presence of high molecular risk (HMR) mutations significantly affected survival, counterbalancing the effect of aging. Indeed, elderly patients with <2 HMR mutated genes had a comparable survival to older patients with ≥2 HMR mutations. Given that responses were not influenced by age, older age per se should not be a limitation for ruxolitinib administration. NGS analysis of HMR mutations also confirmed a strong predictive value in elderly patients.

Differences in presenting features, outcome and prognostic models in patients with primary myelofibrosis and post-polycythemia vera and/or post-essential thrombocythemia myelofibrosis treated with ruxolitinib. New perspective of the MYSEC-PM in a large multicenter study⁎

Recently, the myelofibrosis secondary to PV and ET prognostic model (MYSEC-PM) was introduced to assess prognosis in myelofibrosis (MF) secondary to polycythemia vera and essential thrombocythemia (post-PV and post-ET MF), replacing the International Prognostic Scoring System (IPSS) and/or Dynamic IPSS (DIPSS) that was applied for primary MF (PMF). In a cohort of 421 ruxolitinib (RUX)-treated patients (post-PV and post-ET MF: 44.2%), we evaluated the following: (1) disease phenotype, responses, and toxicity to RUX; and (2) performance of the MYSEC-PM in post-PV or post-ET MF. While the IPSS failed to correctly stratify post-PV or post-ET MF patients at diagnosis, the MYSEC-PM identified 4 risk categories projected at significantly different survival probability (P < .001). Additionally, the MYSEC-PM maintained a prognostic value in post-PV and post-ET MF also when used over time, at RUX start. Notably, the MYSEC-PM reclassified 41.8% and 13.6% of patients into a lower and higher risk category, respectively. Finally, patients at intermediate-1 risk had significantly higher spleen responses and lower hematological toxicities compared to higher risk patients. Compared to PMF, post-PV and post-ET MF presented a more hyperproliferative disease, with higher leukocyte and/or platelet count and hemoglobin levels both at diagnosis and at RUX start. Despite comparable response rates, post-PV and post-ET MF had lower rate of RUX-induced anemia and thrombocytopenia at 3 and 6 months. The study validates MYSEC-PM in post-PV and post-ET MF prognostication. Post-PV or post-ET MF represents a separate entity compared to PMF in terms of clinical manifestations and toxicity to RUX.

Epidemiology, outcome, and risk factors for infectious complications in myelofibrosis patients receiving ruxolitinib: A multicenter study on 446 patients

Infections represent one of the major concerns regarding the utilization of ruxolitinib (RUX) in patients with myelofibrosis. With the aim to investigate epidemiology, outcome and risk factors for infections in RUX-exposed patients, we collected clinical and laboratory data of 446 myelofibrosis patients treated with RUX between June 2011 and November 2016 in 23 European Hematology Centers. After a median RUX exposure of 23.5 months (range, 1-56), 123 patients (28%) experienced 161 infectious events (grades 3-4 32%, fatal 9%), for an incidence rate of 17 cases per 100 pts/y. The rate of infections tended to decrease over time: 14% of patients developed the first infection within 6 months, 5% between 6 and 12 months, 3.7% between 12 and 18 months, 3.4% between 18 and 24 months, and 7.9% thereafter (P < .0001). Respiratory tract infections were more frequently observed (81 events, 50%), and bacteria were the most frequent etiological agents (68.9%). However, also viral (14.9%) and fungal infections (2.5%) were observed. In multivariate analysis, previous infectious event (HR 2.54; 95% CI, 1.51-4.28; P = .0005) and high international prognostic score system category (IPSS) (HR 1.53; 95% CI, 1.07-2.20; P = .021) significantly correlated with higher infectious risk. On the contrary, spleen reduction ≥50% from baseline after 3 months of treatment (P = .02) was associated with better infection-free survival. Taken together, these findings reinforce the concept of disease severity as the most important risk factor for infections, and describe, for the first time, that a positive therapeutic effect in reducing splenomegaly may also reduce subsequent infectious complications.

The relevance of a low JAK2V617F allele burden in clinical practice: a monocentric study

Since low JAK2^V617F allele burden (AB) has been detected also in healthy subjects, its clinical interpretation may be challenging in patients with chronic myeloproliferative neoplasms (MPNs). We tested 1087 subjects for JAK2^V617F mutation on suspicion of hematological malignancy. Only 497 (45.7%) patients were positive. Here we present clinical and laboratory parameters of a cohort of 35/497 patients with an AB ≤ 3%.

Overall, 22/35 (62.9%) received a WHO-defined diagnosis of MPN and in 14/35 cases (40%) diagnosis was supported by bone marrow (BM) histology (‘’Histology-based’’ diagnosis). In patients that were unable or refused to perform BM evaluation, diagnosis relied on prospective clinical observation (12 cases, 34.3%) and molecular monitoring (6 cases, 17.1%) (‘’Clinical-based’’ or ‘’Molecular-based’’ diagnosis, respectively). In 11/35 (31.4%) patients, a low JAK2^V617F AB was not conclusive of MPN. The probability to have a final hematological diagnosis (ET/PV/MF) was higher in patients with thrombocytosis than in patients with polyglobulia (73.7% vs 57.1%, respectively). The detection of AB ≥ 0.8% always corresponded to an overt MPN phenotype. The repetition of JAK2^V617F evaluation over time timely detected the spontaneous expansion (11 cases) or reduction (4 cases) of JAK2^V617F-positive clones and significantly oriented the diagnostic process.

Our study confirms that histology is relevant to discriminate small foci of clonal hematopoiesis with uncertain clinical significance from a full blown disease. Remarkably, our data suggest that a cut-off of AB ≥ 0.8% is very indicative for the presence of a MPN. Monitoring of the AB over time emerged as a convenient and non-invasive method to assess clonal hematopoiesis expansion.

Baseline factors associated with response to ruxolitinib: an independent study on 408 patients with myelofibrosis

In patients with Myelofibrosis (MF) treated with ruxolitinib (RUX), the response is unpredictable at therapy start. We retrospectively evaluated the impact of clinical/laboratory factors on responses in 408 patients treated with RUX according to prescribing obligations in 18 Italian Hematology Centers. At 6 months, 114 out of 327 (34.9%) evaluable patients achieved a spleen response. By multivariable Cox proportional hazard regression model, pre-treatment factors negatively correlating with spleen response were: high/intermediate-2 IPSS risk (p=0.024), large splenomegaly (p=0.017), transfusion dependency (p=0.022), platelet count <200×10⁹/l (p=0.028), and a time-interval between MF diagnosis and RUX start >2 years (p=0.048). Also, patients treated with higher (≥10 mg BID) average RUX doses in the first 12 weeks achieved higher response rates (p=0.019). After adjustment for IPSS risk, patients in spleen response at 6 months showed only a trend for better survival compared to non-responders. At 6 months, symptoms response was achieved by 85.5% of 344 evaluable patients; only a higher (>20) Total Symptom Score significantly correlated with lower probability of response (p<0.001). Increased disease severity, a delay in RUX start and titrated doses <10 mg BID were associated with patients achievinglower response rates. An early treatment and higher RUX doses may achieve better therapeutic results.

Assessing the thrombotic risk of patients with essential thrombocythemia in the genomic era

The molecular characterization of myeloproliferative neoplasms, including essential thrombocythemia (ET), has enabled deeper understanding of their pathogenesis. A driver lesion, namely, Janus kinase (JAK)2V617F, calreticulin (CALR) or myeloproliferative leukemia (MPL) gene mutation can be identified in the vast majority of patients. Each of these mutations is associated with distinct clinical features and may modulate the patients' clinical course, risk of complications, including vascular events, and survival. JAK2V617F appears to be a risk-modifying mutation and has been shown to increase the likelihood of thrombotic events in patients with ET across studies. As such, it has been included in prognostic models and its presence may influence treatment decisions. The association of CALR and MPL mutations with the incidence of vascular events has been less clear. Even more limited information is available on the contribution of additional non-driver lesions to the thrombotic risk. In this review we discuss the available evidence on the role of recurrent mutations in the risk of thrombotic complications in patients with ET and how these mutations weigh into modern prognostic scores.

Comparison of JAK2V617F -positive essential thrombocythaemia and early primary myelofibrosis: The impact of mutation burden and histology

An accurate histological diagnosis may distinguish essential thrombocythaemia (ET) from early primary myelofibrosis (early-PMF), which is associated with worse outcome. Outcome of ET is also negatively affected by the presence of the JAK2^V617F mutation. To investigate the impact of JAK2^V617F mutation burden and histology on outcome, we collected 475 WHO-diagnosed ET (69.2%) or early-PMF JAK2^V617F -positive patients followed in 4 Italian haematology centers. JAK2^V617F allele burden was ≤50% in 90% and 87% of ET and early-PMF patients, respectively (P = .34). During follow-up, 32 (9.7%) ET and 18 (12.3%) early-PMF patients experienced 59 thrombotic events, and 27 patients (5.6%) and 6 (1.2%) patients evolved to myelofibrosis and acute leukemia, respectively. At last contact, 28 (5.8%) patients had died. In early-PMF compared to ET, the 10-year mortality rates (6.7% and 4.3%, P = .73), leukemic transformation rates (1.4% and 1.2%, P = .45), and thrombosis rates (16.7% and 12.2%, P = .12) were comparable. Only progression to overt myelofibrosis at 10 years was significantly worse (11.4% and 1.5%, P = .004). In multivariate analysis, a higher (>50%) JAK2^V617F burden was significantly correlated with fibrotic progression and histology. Considering JAK2^V617F -positive disease, a higher (>50%) JAK2^V617F burden and histological classification are independent prognostic risk factors for disease progression. These findings reinforce the need for standardized detection of this mutation.

Clinical Manifestation of Calreticulin Gene Mutations in Essential Thrombocythemia without Janus Kinase 2 and MPL Mutations: A Chinese Cohort Clinical Study

BACKGROUND

Recently, calreticulin (CALR) gene mutations have been identified in patients with essential thrombocythemia (ET). A high-frequency of ET cases without Janus kinase 2 (JAK2) mutations contain CALR mutations and exhibit clinical characteristics different from those with mutant JAK2. Thus, we investigated the frequency and clinical features of Chinese patients of Han ethnicity with CALR mutations in ET.

METHODS

We recruited 310 Chinese patients of Han ethnicity with ET to analyze states of CALR, JAK2V617F, and MPLW515 mutations by polymerase chain reaction and direct sequencing. We analyzed the relationship between the mutations and clinical features.

RESULTS

CALR, JAK2V617F, and MPLW515 mutations were detected in 30% (n = 92), 48% (n = 149), and 1% (n = 4) of patients with ET, respectively. The mutation types of CALR involved deletion and insertion of base pairs. Most of them were Type 1 (52-bp deletion) and Type 2 (5-bp insertion, TTGTC) mutations, leading to del367fs46 and ins385fs47, respectively. The three mutations were exclusive. Clinically, patients with mutated CALR had a lower hemoglobin level, lower white blood cell (WBC) count, and higher platelet count compared to those with mutated JAK2 (P < 0.05). Furthermore, a significant difference was found in WBCs between wild-type patients (triple negative for JAK2, MPL, and CALR mutations) and patients with JAK2 mutations. Patients with CALR mutations predominantly clustered into low or intermediate groups according to the International Prognostic Score of thrombosis for ET (P < 0.05).

CONCLUSIONS

CALR mutations were frequent in Chinese patients with ET, especially in those without JAK2 or MPL mutations. Compared with JAK2 mutant ET, CALR mutant ET showed a different clinical manifestation and an unfavorable prognosis. Thus, CALR is a potentially valuable diagnostic marker and therapeutic target in ET.

Risk factors for infections in myelofibrosis: role of disease status and treatment. A multicenter study of 507 patients

Although infectious complications represent a relevant cause of morbidity and mortality in patients with myelofibrosis (MF), little is known about their incidence, outcome and risk factors. We retrospectively evaluated a cohort of 507 MF patients, diagnosed between 1980 and 2014 in five Italian hematology centers, to define the epidemiology of infections and describe the impact of ruxolitinib (RUX) treatment. Overall, 112 patients (22%) experienced 160 infectious events (grade 3-4, 45%) for an incidence rate of 3.9% per patient-year. Infections were mainly bacterial (78%) and involving the respiratory tract (52% of cases). Also, viral (11%) and fungal infections (2%) were recorded. Overall, infections were fatal in 9% of the cases. Among baseline features, high/intermediate-2 IPSS category (HR 1.8, 95%CI:1.2-2.7; P = 0.02) and spleen length ≥10 cm below left costal margin (HR 1.6, 95%CI:1.1-2.5; P = 0.04) were associated with higher infectious risk in multivariate analysis. Overall, the rate of infections was higher in the cohort of 128 RUX-treated patients (44% vs. 20%, P < 0.001). In conclusion, IPSS-category and splenomegaly, emerged as the main risk factors for infections in MF. RUX-treated patients experienced significantly more infection episodes; however, future prospective studies are needed to isolate the confounding contribution of other risk factors such as disease stage. Am. J. Hematol. 92:37-41, 2017. © 2016 Wiley Periodicals, Inc.

Circulating Calreticulin Is Increased in Myelofibrosis: Correlation with Interleukin-6 Plasma Levels, Bone Marrow Fibrosis, and Splenomegaly

Myelofibrosis (MF) is a clonal neoplasia of the hemopoietic stem/progenitor cells associated with genetic mutations in the Janus kinase 2 (JAK2), myeloproliferative leukemia virus oncogene (MPL), and calreticulin (CALR) genes. MF is also characterized by a state of chronic inflammation. Calreticulin (CRT), as a multifunctional protein, is involved in a spectrum of cellular processes including inflammation, autoimmunity, and cancer initiation/progression. Based on this background, we hypothesised that in MF circulating CRT might reflect the inflammatory process. In the present study we show that circulating CRT is increased in MF patients compared to healthy controls. Also, in MF, CRT levels highly correlate with bone marrow fibrosis, splenomegaly, and Interleukin-6 (IL-6) plasma levels. In turn, higher IL-6 levels also correlated with disease severity in terms of increased spleen size, bone marrow fibrosis, number of circulating CD34⁺ cells, and lower hemoglobin values. These results demonstrate that the circulating CRT takes part in the inflammatory network of MF and correlates with aggressiveness of the disease.

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.

Novel germline mutations in the calreticulin gene: implications for the diagnosis of myeloproliferative neoplasms

Mutations in the calreticulin (CALR) gene are found in the majority of Janus kinase 2-negative myeloproliferative neoplasms MPN and, thus far, have exclusively been reported as acquired, somatic mutations. We assessed the mutational status of exon 9 of the CALR gene in 2000 blood samples submitted to our centre and identified 12 subjects (0.6%) harbouring distinctive CALR mutations, all with an allelic frequency of 50% and all involving indels occurring as multiples of 3 bp. Buccal cell samples obtained from these patients confirmed the germline nature of the mutations. Importantly, these germline mutations were not diagnostic of MPN. We thus report for the first time the identification and confirmation of germline mutations in CALR distinct from those somatic mutations that define classical MPN. The finding of a non-standard CALR mutation with an allelic frequency of 50% should raise suspicion of the possibility of a germline CALR mutation and these cases investigated further.

Characterization of CD34+ hematopoietic progenitor cells in JAK2V617F and CALR-mutated myeloproliferative neoplasms

Mutations in JAK2 or CALR are observed in patients with myeloproliferative neoplasms (MPN). To get further insight in the dynamics of the mutant clone, we assessed the mutant allele burden in hematopoietic stem cells (HSCs), hematopoietic progenitor cells (HPCs) and granulocytes from 138 patients [51 polycythemia vera (PV), 58 essential thrombocythemia (ET) and 29 myelofibrosis (MF)]. CALR-mutated ET patients harbored a higher mutant load at progenitor level than JAK2V617F-positive ET (HSCs: 39.9% vs 7.5% p<0.001, HPCs: 32.7% vs 7.7% p<0.001). Moreover, HSCs of CALR-mutated ET patients showed a similar mutational load than patients with CALR-mutated MF (39.9% vs 48.2%, p=0.17). Regarding JAK2V617F MPN, PV and ET patients showed a low mutational burden at progenitor level whereas in the myelofibrotic phase the dominance of the mutated clone was a constant finding. In conclusion, the size of the mutated clone in chronic phase MPN is different according to genotype with CALR-mutated ET showing a pattern similar to that observed in MF.

The 2016 revision of WHO classification of myeloproliferative neoplasms: Clinical and molecular advances

Clinical evidence supports the need of changing the diagnostic criteria of the 2008 updated WHO classification for polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). In JAK2-mutated patients who show characteristic bone marrow (BM) morphology, clinical studies demonstrated that a hemoglobin level of 16.5g/dL in men and 16.0g/dl for women or a hematocrit value of 49% in men and 48% in women are the optimal cut off levels for distinguishing JAK2-mutated ET from "masked/prodromal" PV. Therefore BM morphology was upgraded to a major diagnostic criterion. Regarding ET the key issue was to improve standardization of prominent BM features enhancing differentiation between "true" ET and prefibrotic/early primary myelofibrosis (prePMF). These two entities have shown a different epidemiology and clinical outcomes. Concerning prePMF a more explicit clinical characterization of minor criteria is mandated for an improved distinction from ET and overt PMF and accurate diagnosis and outcome prediction.

Antiplatelet therapy versus observation in low-risk essential thrombocythemia with a CALR mutation

The role of antiplatelet therapy as primary prophylaxis of thrombosis in low-risk essential thrombocythemia has not been studied in randomized clinical trials. We assessed the benefit/risk of low-dose aspirin in 433 patients with low-risk essential thrombocythemia (271 with a CALR mutation, 162 with a JAK2(V617F) mutation) who were on antiplatelet therapy or observation only. After a follow up of 2215 person-years free from cytoreduction, 25 thrombotic and 17 bleeding episodes were recorded. In CALR-mutated patients, antiplatelet therapy did not affect the risk of thrombosis but was associated with a higher incidence of bleeding (12.9 versus 1.8 episodes per 1000 patient-years, P=0.03). In JAK2(V617F)-mutated patients, low-dose aspirin was associated with a reduced incidence of venous thrombosis with no effect on the risk of bleeding. Coexistence of JAK2(V617F)-mutation and cardiovascular risk factors increased the risk of thrombosis, even after adjusting for treatment with low-dose aspirin (incidence rate ratio: 9.8; 95% confidence interval: 2.3-42.3; P=0.02). Time free from cytoreduction was significantly shorter in CALR-mutated patients with essential thrombocythemia than in JAK2(V617F)-mutated ones (median time 5 years and 9.8 years, respectively; P=0.0002) and cytoreduction was usually necessary to control extreme thrombocytosis. In conclusion, in patients with low-risk, CALR-mutated essential thrombocythemia, low-dose aspirin does not reduce the risk of thrombosis and may increase the risk of bleeding.